diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 82c6d18..00d633b 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -121,7 +121,7 @@ jobs:
           $v = (Select-String -Path Cargo.toml -Pattern '^version = "(.*)"').Matches[0].Groups[1].Value
           $p = "TeXora-$v-windows-x64"
           New-Item -ItemType Directory -Force "stage/$p", "dist/$v" | Out-Null
-          Copy-Item target/release/TeXora.exe, target/release/pdfium.dll, README.md, CREDITS.md, LICENSE "stage/$p/"
+          Copy-Item target/release/TeXora.exe, target/release/pdfium.dll, README.md, CREDITS.md, THIRD-PARTY-LICENSES.md, LICENSE "stage/$p/"
           Compress-Archive -Path "stage/$p" -DestinationPath "dist/$v/$p.zip"
           "PKG=$p" | Out-File -Append $env:GITHUB_ENV
           "VER=$v" | Out-File -Append $env:GITHUB_ENV
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 94c29b7..f7da34a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,31 @@
 
 All notable changes to TeXora. The newest version is first.
 
+## 1.5.0
+
+### Security
+
+- ffmpeg opens a clip with `-nostdin -protocol_whitelist file` and a list of real video formats only, so a file that is really a playlist or a concat list cannot make ffmpeg read other files or web addresses. Tested with such files: plain ffmpeg follows them, TeXora's ffmpeg refuses them.
+- VLC gets the clip's full path after `--`, so a file name starting with `-` is never read as an option, and only files that really are videos (from their first bytes, not their name): never a playlist.
+- Which player runs, and where it is, comes only from your own Settings. A presentation, its `.tex` file, a PDF or anything in its folder can never set the program or add arguments; this is tested.
+
+### New
+
+- Videos and GIFs in your slides: `\usepackage{texoravideo}` and `\includevideo[width=0.5\textwidth]{clip.mp4}`. TeXora ships the LaTeX package and finds it by itself when it compiles. A second optional argument takes `autoplay`, `loop`, `posterat=<percent>` and `poster=<image>`.
+- **GIFs play by themselves.** **MP4 playback uses VLC or ffmpeg installed on your computer**: with ffmpeg the clip plays inside the slide, with VLC in VLC's own window. TeXora contains no video decoder and never downloads or installs one.
+- Settings > Video chooses the player (Auto, ffmpeg, VLC or Off), with a path and a **Test** button for each.
+- A video that needs a player when none is installed says "This video needs VLC or ffmpeg installed on your computer.", with **Get VLC**, **Get ffmpeg** and **Copy install command**. TeXora only opens the pages and copies the command; it never runs it.
+- Before compiling, TeXora makes each clip's poster in a `texora-video` folder (again only when the clip changes; a video's poster needs ffmpeg), so every PDF viewer shows the poster; a click in TeXora plays or pauses the clip, and another slide stops it and its ffmpeg.
+- A missing file, a file that is not a video or a path outside the presentation's folder shows a message over the poster and under Problems.
+- A video can be in the `.tex` file's folder or in any folder inside it; a video in a folder is written with the folder name, as in `\includevideo{videos/clip.mp4}`. "Video not found" says this in plain words.
+- One poster per video, however often it is used; posters no longer used are removed.
+- A new template, **Video Guide**, explains `\includevideo` slide by slide: what you need, a video, a looping GIF, every option, posters, overlays and what to do when a clip does not play. Its sample video and GIF are saved in a `media` folder beside the new file.
+
+### Fixed
+
+- Check packages finds packages, classes, themes and TikZ libraries of your own that sit beside the `.tex` file (or in a folder you name, as in `\usepackage{styles/house}`), as LaTeX does, and no longer reports them as missing or suggests `tlmgr install` for them (#3).
+- The control bar under an animation (first, previous, play/pause, next, last) works again: its buttons now get the click, instead of the slide underneath taking it.
+
 ## 1.4.1
 
 ### Fixed
diff --git a/CREDITS.md b/CREDITS.md
index 80b117b..88e58ab 100644
--- a/CREDITS.md
+++ b/CREDITS.md
@@ -4,6 +4,10 @@ TeXora is original code by Khalid Alkhaldi, licensed under PolyForm Noncommercia
 bundled sample lecture and the five presentation templates are neutral placeholder text written for it.
 
 - PDFium, prebuilt by bblanchon/pdfium-binaries: BSD-3-Clause and Apache-2.0. Downloaded into `vendor/` when building.
+- md-5 (names video posters): MIT or Apache-2.0. GIFs are decoded by the image crate.
+- No video decoder, ffmpeg, VLC, libvlc or codec library is included. MP4 playback uses VLC or ffmpeg
+  installed on your computer, started as separate programs. Every library inside TeXora, with its
+  licence, is listed in `THIRD-PARTY-LICENSES.md`.
 - egui and eframe: MIT or Apache-2.0.
 - pdfium-render: MIT or Apache-2.0.
 - ureq, serde, serde_json, image, rfd, display-info, dirs: MIT or Apache-2.0 style licences.
diff --git a/Cargo.lock b/Cargo.lock
index 8d6df97..9344cd1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -142,6 +142,15 @@ version = "2.13.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3ded4057c258ba199e2d26386d3af3780957ecaee6c4ef4041c6b4b8b97c0b06"
 
+[[package]]
+name = "block-buffer"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2f6c7dbe95a6ed67ad9f18e57daf93a2f034c524b99fd2b76d18fdfeb6660aa"
+dependencies = [
+ "hybrid-array",
+]
+
 [[package]]
 name = "block2"
 version = "0.5.1"
@@ -327,6 +336,12 @@ dependencies = [
  "bytemuck",
 ]
 
+[[package]]
+name = "color_quant"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3d7b894f5411737b7867f4827955924d7c254fc9f4d91a6aad6b097804b1018b"
+
 [[package]]
 name = "combine"
 version = "4.6.9"
@@ -366,6 +381,12 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "const-oid"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a6ef517f0926dd24a1582492c791b6a4818a4d94e789a334894aa15b0d12f55c"
+
 [[package]]
 name = "cookie"
 version = "0.18.2"
@@ -456,6 +477,15 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
 
+[[package]]
+name = "crypto-common"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce6e4c961d6cd6c9a86db418387425e8bdeaf05b3c8bc1411e6dca4c252f1453"
+dependencies = [
+ "hybrid-array",
+]
+
 [[package]]
 name = "cursor-icon"
 version = "1.2.0"
@@ -468,6 +498,17 @@ version = "0.5.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9e9de72ce2ad1f90dc62fa25f0f430ef85eb4b0d8fa0be4f30373bc40a21d28e"
 
+[[package]]
+name = "digest"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1dd6dbb5841937940781866fa1281a1ff7bd3bf827091440879f9994983d5c2"
+dependencies = [
+ "block-buffer",
+ "const-oid",
+ "crypto-common",
+]
+
 [[package]]
 name = "dirs"
 version = "7.0.0"
@@ -990,6 +1031,16 @@ dependencies = [
  "r-efi 6.0.0",
 ]
 
+[[package]]
+name = "gif"
+version = "0.14.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee8cfcc411d9adbbaba82fb72661cc1bcca13e8bba98b364e62b2dba8f960159"
+dependencies = [
+ "color_quant",
+ "weezl",
+]
+
 [[package]]
 name = "gl_generator"
 version = "0.14.0"
@@ -1169,6 +1220,15 @@ version = "1.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6dbf3de79e51f3d586ab4cb9d5c3e2c14aa28ed23d180cf89b4df0454a69cc87"
 
+[[package]]
+name = "hybrid-array"
+version = "0.4.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "27f864f10dfb56725ce5ce5472bc52252c8f93a4ab86327122cebf62c5f59a17"
+dependencies = [
+ "typenum",
+]
+
 [[package]]
 name = "iana-time-zone"
 version = "0.1.65"
@@ -1305,6 +1365,8 @@ checksum = "85ab80394333c02fe689eaf900ab500fbd0c2213da414687ebf995a65d5a6104"
 dependencies = [
  "bytemuck",
  "byteorder-lite",
+ "color_quant",
+ "gif",
  "moxcms",
  "num-traits",
  "png",
@@ -1530,6 +1592,16 @@ version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4facc753ae494aeb6e3c22f839b158aebd4f9270f55cd3c79906c45476c47ab4"
 
+[[package]]
+name = "md-5"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "69b6441f590336821bb897fb28fc622898ccceb1d6cea3fde5ea86b090c4de98"
+dependencies = [
+ "cfg-if",
+ "digest",
+]
+
 [[package]]
 name = "memchr"
 version = "2.8.3"
@@ -2863,7 +2935,7 @@ dependencies = [
 
 [[package]]
 name = "texora"
-version = "1.4.1"
+version = "1.5.0"
 dependencies = [
  "dirs",
  "display-info",
@@ -2872,6 +2944,7 @@ dependencies = [
  "embed-resource",
  "fontique",
  "image",
+ "md-5",
  "miniz_oxide 0.8.9",
  "pdfium-render",
  "rfd",
@@ -3072,6 +3145,12 @@ dependencies = [
  "rustc-hash 2.1.3",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.20.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6f5e870be6c3b371b77fe0ee0bafb859fa4964b4404c27de1d380043c4dda20"
+
 [[package]]
 name = "unicode-bidi"
 version = "0.3.18"
diff --git a/Cargo.toml b/Cargo.toml
index 1be8b8a..002b962 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "texora"
-version = "1.4.1"
+version = "1.5.0"
 edition = "2021"
 description = "TeXora: a LaTeX-native presenter for Beamer and PDF slides"
 license = "PolyForm-Noncommercial-1.0.0"
@@ -15,7 +15,7 @@ path = "src/main.rs"
 eframe = { version = "0.37", default-features = false, features = ["glow", "default_fonts", "wayland", "x11", "clipboard", "links", "system_fonts"] }
 egui = "0.37"
 pdfium-render = "0.9.5"
-image = { version = "0.25", default-features = false, features = ["png"] }
+image = { version = "0.25", default-features = false, features = ["png", "gif", "jpeg"] }
 rfd = "0.17"
 serde = { version = "1", features = ["derive"] }
 unicode-bidi = "0.3"
@@ -24,6 +24,10 @@ serde_json = "1"
 ureq = { version = "3", features = ["json"] }
 display-info = "0.5"
 dirs = "7"
+# Video inside slides: GIFs are decoded by the image crate. TeXora contains no other video decoder;
+# MP4 and other formats play through ffmpeg or VLC that the person installed (src/video.rs). md-5 names
+# the posters.
+md-5 = "0.11"
 
 # Fonts for other writing systems (Arabic, Hebrew, Chinese, Japanese, Korean, Hindi, Thai...) come from
 # the computer itself. On Linux, fontconfig is opened when the program runs instead of being linked, so
diff --git a/README.md b/README.md
index f21343a..3624efb 100644
--- a/README.md
+++ b/README.md
@@ -55,7 +55,8 @@ The audience window shows only the slide, fullscreen on a projector or second sc
   source, from a `.pdfpc` file, or from a Markdown file beside the presentation. **Edit notes** for any
   slide right in the notes panel.
 - **Animations and videos**: animations made with the LaTeX `animate` package play on the slide, with
-  autoplay, looping and play controls; video clips open in your video player.
+  autoplay, looping and play controls. Videos and GIFs placed with the built-in `texoravideo` package
+  play inside the slide; `\movie` and media9 clips open in your video player.
 - **Drawing and pointing**: pen, highlighter, eraser, a laser pointer in several colours, and zoom into
   an area. Ink is kept per slide.
 - **Zoom** any slide with the wheel or a pinch, around the pointer.
@@ -128,11 +129,13 @@ Nothing else is needed to present PDFs: each package carries the program and its
    LaTeX project**, pick a recent file, or drop a file on the window. **Try the sample lecture** opens
    a ready-made talk to explore.
 
-   **New LaTeX presentation** offers eight templates, each a complete Beamer file with speaker notes:
-   Classic Green, Midnight, Minimal White, Conference and Sunrise, and three animated ones. **Motion
+   **New LaTeX presentation** offers nine templates, each a complete Beamer file with speaker notes:
+   Classic Green, Midnight, Minimal White, Conference and Sunrise, and four animated ones. **Motion
    Lab** shows animations drawn with TikZ, **Flipbook** plays the frames of a GIF and charts that
-   grow, and **Media Studio** has a video clip and charts that draw themselves. Flipbook and Media
-   Studio save their pictures and clip in a `media` folder beside the new file.
+   grow, **Media Studio** has a video clip and charts that draw themselves, and **Video Guide**
+   explains `\includevideo` slide by slide, with a video and a GIF that play inside the slides.
+   Flipbook, Media Studio and Video Guide save their pictures and clips in a `media` folder beside
+   the new file.
 3. A `.tex` file is compiled for you. Edit it in the **LaTeX studio** (Cmd/Ctrl+E), or in your own
    LaTeX editor: the slides rebuild either way.
 4. Press **F5** to show the slides to the room, then move with the arrow keys or **Space**.
@@ -358,7 +361,48 @@ For a large GIF, shrink it while splitting, for example
 `ffmpeg -i anim.gif -vf "fps=10,scale=640:-1" frames/f%d.png`, and keep the `frames` folder beside
 the `.tex` file.
 
-**Videos.** Use Beamer's `\movie` (the `multimedia` package) or media9's `\includemedia`. Each shows a
+**Videos inside the slide.** TeXora comes with its own LaTeX package, `texoravideo`, and finds it by
+itself when it compiles; there is no package to install or copy. **GIFs play by themselves. MP4
+playback uses VLC or ffmpeg installed on your computer**: with ffmpeg the clip plays inside the slide,
+with VLC in VLC's own window. TeXora contains no video decoder and never downloads or installs one.
+
+```latex
+\usepackage{texoravideo}
+\hypersetup{hidelinks}
+...
+\includevideo[width=0.5\textwidth]{clip.mp4}
+\includevideo[height=5cm][loop,autoplay]{media/wave.gif}
+\includevideo[width=\textwidth][poster=cover.png,posterat=25]{talk.mp4}
+```
+
+- The first optional argument goes to `\includegraphics` as it is. The second takes `autoplay`, `loop`,
+  `posterat=<percent>` (where the poster is taken from; default the first frame) and `poster=<image>`.
+- The video must be in the `.tex` file's folder, or in a folder inside it (any name). If it is in a
+  folder, write the folder name too: `{videos/clip.mp4}`. Otherwise TeXora shows "Video not found".
+- Before LaTeX runs, TeXora makes one poster per video in a `texora-video` folder beside the
+  presentation, again only when the clip changes; if a video is used with different `posterat`
+  values, the first counts. `texora-video/index.json` keeps what was found, so the
+  PDF still plays when opened later. Every PDF viewer shows the poster; only TeXora plays the clip.
+- Click to play, click again to pause; another slide stops it, and overlay steps of the same slide keep
+  it playing. GIFs work the same way, with no splitting.
+- GIFs always play. MP4 and other formats play when ffmpeg or VLC is installed; ffmpeg also makes
+  their posters. Choose the player in **Settings > Video** (Auto, ffmpeg, VLC or Off); each has a path
+  field and a **Test** button.
+- No player installed: the clip says "This video needs VLC or ffmpeg installed on your computer.", with
+  **Get VLC** (videolan.org), **Get ffmpeg** (ffmpeg.org/download.html) and, on macOS and Linux,
+  **Copy install command** (`brew install ffmpeg`, or `sudo apt install ffmpeg`). TeXora copies the
+  command; you run it yourself.
+- A missing file, a file that is not a video, or a path outside the presentation's folder (an absolute
+  path, `..`, a link leading out, a web address) shows a message over the poster and under Problems.
+  Names may have spaces and accents, but not `%` or `#`.
+- ffmpeg and VLC run as separate programs, with a list of arguments and never through a shell; TeXora
+  ends ffmpeg when you leave the slide. Sound is not played yet.
+- ffmpeg reads a clip with `-nostdin -protocol_whitelist file` and real video formats only, so a file
+  that is really a playlist or concat list cannot reach other files or the web. VLC gets the full path
+  after `--`, and only real video files. Which program runs comes only from your Settings: a
+  presentation or anything in its folder can never set it or add arguments.
+
+**Videos in your video player.** Use Beamer's `\movie` (the `multimedia` package) or media9's `\includemedia`. Each shows a
 play button in the presenter view. Click it and the video opens in your computer's video player,
 which you can move to the projector. The player may start paused, so press play there.
 
@@ -374,7 +418,7 @@ which you can move to the projector. The player may start paused, so press play
   unpacked by TeXora.
 - Write `\movie` without `externalviewer`. `\movie[externalviewer]` and `\href{run:...}` links are not
   opened yet, and links to local files (`\href{file:...}`) are not opened.
-- Videos do not play inside the slide itself.
+- These clips do not play inside the slide; use `\includevideo` for that.
 
 ### Presenting to the room
 
@@ -487,5 +531,3 @@ Copyright 2026 Khalid Alkhaldi. Licensed under [PolyForm Noncommercial 1.0.0](LI
 non-commercial purpose, including personal use, study, teaching, research and non-profit work. Commercial
 use needs the author's permission. The app icon and Home picture are the author's artwork and are not
 covered by the licence. See [CREDITS.md](CREDITS.md) for the libraries and fonts used.
-
-Made by Khalid Alkhaldi.
diff --git a/THIRD-PARTY-LICENSES.md b/THIRD-PARTY-LICENSES.md
new file mode 100644
index 0000000..27a5a02
--- /dev/null
+++ b/THIRD-PARTY-LICENSES.md
@@ -0,0 +1,415 @@
+# Third-party licences
+
+TeXora is built from the libraries below; each keeps its own licence. This list is made by
+`scripts/third-party.py` from Cargo's records, so it matches the program exactly.
+
+## Not included
+
+TeXora contains **no video decoder, encoder or player**: no H.264 or other codec, no ffmpeg, no VLC
+or libvlc. GIFs are decoded by the `image` library. **MP4 playback uses VLC or ffmpeg installed on
+your computer**, started as separate programs; TeXora never downloads, installs, ships or updates them.
+ffmpeg and VLC have their own licences (LGPL/GPL), which apply to the copies you install.
+
+## Shipped beside the program
+
+| Component | Licence | Source |
+|---|---|---|
+| PDFium (prebuilt by bblanchon/pdfium-binaries) | BSD-3-Clause and Apache-2.0 | https://github.com/bblanchon/pdfium-binaries |
+| Inter font (Rasmus Andersson) | SIL Open Font License 1.1 | https://rsms.me/inter/ |
+| Hack and Ubuntu Light fonts (inside egui) | MIT; Ubuntu Font Licence | https://github.com/emilk/egui |
+
+## Rust libraries built into the program (391)
+
+| Library | Version | Licence | Source |
+|---|---|---|---|
+| accesskit | 0.25.2 | MIT OR Apache-2.0 | https://github.com/AccessKit/accesskit |
+| adler2 | 2.0.1 | 0BSD OR MIT OR Apache-2.0 | https://github.com/oyvindln/adler2 |
+| ahash | 0.8.12 | MIT OR Apache-2.0 | https://github.com/tkaitchuck/ahash |
+| android-activity | 0.6.1 | MIT OR Apache-2.0 | https://github.com/rust-mobile/android-activity |
+| android-properties | 0.2.2 | MIT | https://github.com/miklelappo/android-properties |
+| android_system_properties | 0.1.6 | MIT OR Apache-2.0 | https://github.com/nical/android_system_properties |
+| arboard | 3.7.0 | MIT OR Apache-2.0 | https://github.com/1Password/arboard |
+| arrayvec | 0.7.8 | MIT OR Apache-2.0 | https://github.com/bluss/arrayvec |
+| as-raw-xcb-connection | 1.0.1 | MIT OR Apache-2.0 | https://github.com/psychon/as-raw-xcb-connection |
+| atomic-waker | 1.1.2 | Apache-2.0 OR MIT | https://github.com/smol-rs/atomic-waker |
+| base64 | 0.23.1 | MIT OR Apache-2.0 | https://github.com/marshallpierce/rust-base64 |
+| bit-set | 0.10.0 | Apache-2.0 OR MIT | https://github.com/contain-rs/bit-set |
+| bit-vec | 0.9.1 | Apache-2.0 OR MIT | https://github.com/contain-rs/bit-vec |
+| bitflags | 1.3.2 | MIT/Apache-2.0 | https://github.com/bitflags/bitflags |
+| bitflags | 2.13.2 | MIT OR Apache-2.0 | https://github.com/bitflags/bitflags |
+| block-buffer | 0.12.1 | MIT OR Apache-2.0 | https://github.com/RustCrypto/utils |
+| block2 | 0.5.1 | MIT | https://github.com/madsmtm/objc2 |
+| block2 | 0.6.2 | MIT | https://github.com/madsmtm/objc2 |
+| bumpalo | 3.20.3 | MIT OR Apache-2.0 | https://github.com/fitzgen/bumpalo |
+| bytemuck | 1.25.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/Lokathor/bytemuck |
+| bytemuck_derive | 1.12.1 | Zlib OR Apache-2.0 OR MIT | https://github.com/Lokathor/bytemuck |
+| byteorder | 1.5.0 | Unlicense OR MIT | https://github.com/BurntSushi/byteorder |
+| byteorder-lite | 0.1.0 | Unlicense OR MIT | https://github.com/image-rs/byteorder-lite |
+| bytes | 1.12.1 | MIT | https://github.com/tokio-rs/bytes |
+| calloop | 0.13.0 | MIT | https://github.com/Smithay/calloop |
+| calloop | 0.14.5 | MIT | https://github.com/Smithay/calloop |
+| calloop-wayland-source | 0.3.0 | MIT | https://github.com/smithay/calloop-wayland-source |
+| calloop-wayland-source | 0.4.1 | MIT | https://github.com/smithay/calloop-wayland-source |
+| cfg-if | 1.0.5 | MIT OR Apache-2.0 | https://github.com/rust-lang/cfg-if |
+| cgl | 0.3.2 | MIT / Apache-2.0 | https://github.com/servo/cgl-rs |
+| chrono | 0.4.45 | MIT OR Apache-2.0 | https://github.com/chronotope/chrono |
+| clipboard-win | 5.4.3 | BSL-1.0 | https://github.com/DoumanAsh/clipboard-win |
+| codespan-reporting | 0.13.1 | Apache-2.0 | https://github.com/brendanzab/codespan |
+| color | 0.3.3 | Apache-2.0 OR MIT | https://github.com/linebender/color |
+| color_quant | 1.1.0 | MIT | https://github.com/image-rs/color_quant.git |
+| combine | 4.6.9 | MIT | https://github.com/Marwes/combine |
+| concurrent-queue | 2.5.0 | Apache-2.0 OR MIT | https://github.com/smol-rs/concurrent-queue |
+| console_error_panic_hook | 0.1.7 | Apache-2.0/MIT | https://github.com/rustwasm/console_error_panic_hook |
+| console_log | 1.1.0 | MIT/Apache-2.0 | https://github.com/iamcodemaker/console_log |
+| const-oid | 0.10.2 | Apache-2.0 OR MIT | https://github.com/RustCrypto/formats |
+| cookie | 0.18.2 | MIT OR Apache-2.0 | https://github.com/SergioBenitez/cookie-rs |
+| cookie_store | 0.22.1 | MIT OR Apache-2.0 | https://github.com/pfernie/cookie_store |
+| core-foundation | 0.9.4 | MIT OR Apache-2.0 | https://github.com/servo/core-foundation-rs |
+| core-foundation-sys | 0.8.7 | MIT OR Apache-2.0 | https://github.com/servo/core-foundation-rs |
+| core-graphics | 0.23.2 | MIT OR Apache-2.0 | https://github.com/servo/core-foundation-rs |
+| core-graphics-types | 0.1.3 | MIT OR Apache-2.0 | https://github.com/servo/core-foundation-rs |
+| crc32fast | 1.5.4 | MIT OR Apache-2.0 | https://github.com/srijs/rust-crc32fast |
+| crossbeam-utils | 0.8.23 | MIT OR Apache-2.0 | https://github.com/crossbeam-rs/crossbeam |
+| crunchy | 0.2.4 | MIT | https://github.com/eira-fransham/crunchy |
+| crypto-common | 0.2.2 | MIT OR Apache-2.0 | https://github.com/RustCrypto/traits |
+| cursor-icon | 1.2.0 | MIT OR Apache-2.0 OR Zlib | https://github.com/rust-windowing/cursor-icon |
+| deranged | 0.5.9 | MIT OR Apache-2.0 | https://github.com/jhpratt/deranged |
+| digest | 0.11.3 | MIT OR Apache-2.0 | https://github.com/RustCrypto/traits |
+| dirs | 7.0.0 | MIT OR Apache-2.0 | https://codeberg.org/dirs/dirs-rs |
+| dirs-sys | 0.5.0 | MIT OR Apache-2.0 | https://github.com/dirs-dev/dirs-sys-rs |
+| dispatch | 0.2.0 | MIT | http://github.com/SSheldon/rust-dispatch |
+| dispatch2 | 0.3.1 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| display-info | 0.5.10 | Apache-2.0 | https://github.com/nashaofu/display-info.git |
+| displaydoc | 0.2.7 | MIT OR Apache-2.0 | https://github.com/yaahc/displaydoc |
+| dlib | 0.5.3 | MIT | https://github.com/elinorbgr/dlib |
+| document-features | 0.2.12 | MIT OR Apache-2.0 | https://github.com/slint-ui/document-features |
+| downcast-rs | 1.2.1 | MIT/Apache-2.0 | https://github.com/marcianx/downcast-rs |
+| dpi | 0.1.2 | Apache-2.0 AND MIT | https://github.com/rust-windowing/winit |
+| ecolor | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui |
+| eframe | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui/tree/main/crates/eframe |
+| egui | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui |
+| egui-wgpu | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui/tree/main/crates/egui-wgpu |
+| egui-winit | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui/tree/main/crates/egui-winit |
+| egui_glow | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui/tree/main/crates/egui_glow |
+| egui_system_font_provider | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui/tree/main/crates/egui_system_font_provider |
+| either | 1.19.0 | MIT OR Apache-2.0 | https://github.com/rayon-rs/either |
+| emath | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui/tree/main/crates/emath |
+| epaint | 0.37.0 | MIT OR Apache-2.0 | https://github.com/emilk/egui/tree/main/crates/epaint |
+| epaint_default_fonts | 0.37.0 | (MIT OR Apache-2.0) AND OFL-1.1 AND Ubuntu-font-1.0 | https://github.com/emilk/egui/tree/main/crates/epaint_default_fonts |
+| equivalent | 1.0.3 | Apache-2.0 OR MIT | https://github.com/indexmap-rs/equivalent |
+| errno | 0.3.14 | MIT OR Apache-2.0 | https://github.com/lambda-fairy/rust-errno |
+| error-code | 3.4.0 | BSL-1.0 | https://github.com/DoumanAsh/error-code |
+| euclid | 0.22.14 | MIT OR Apache-2.0 | https://github.com/servo/euclid |
+| fax | 0.2.7 | MIT | https://github.com/pdf-rs/fax |
+| fdeflate | 0.3.7 | MIT OR Apache-2.0 | https://github.com/image-rs/fdeflate |
+| fearless_simd | 0.4.1 | Apache-2.0 OR MIT | https://github.com/linebender/fearless_simd |
+| fixedbitset | 0.5.7 | MIT OR Apache-2.0 | https://github.com/petgraph/fixedbitset |
+| flate2 | 1.1.10 | MIT OR Apache-2.0 | https://github.com/rust-lang/flate2-rs |
+| foldhash | 0.1.5 | Zlib | https://github.com/orlp/foldhash |
+| foldhash | 0.2.0 | Zlib | https://github.com/orlp/foldhash |
+| font-types | 0.12.7 | MIT OR Apache-2.0 | https://github.com/googlefonts/fontations |
+| fontique | 0.11.1 | Apache-2.0 OR MIT | https://github.com/linebender/parley |
+| foreign-types | 0.5.0 | MIT/Apache-2.0 | https://github.com/sfackler/foreign-types |
+| foreign-types-macros | 0.2.4 | MIT/Apache-2.0 | https://github.com/sfackler/foreign-types |
+| foreign-types-shared | 0.3.1 | MIT/Apache-2.0 | https://github.com/sfackler/foreign-types |
+| form_urlencoded | 1.2.2 | MIT OR Apache-2.0 | https://github.com/servo/rust-url |
+| futures-core | 0.3.34 | MIT OR Apache-2.0 | https://github.com/rust-lang/futures-rs |
+| futures-task | 0.3.34 | MIT OR Apache-2.0 | https://github.com/rust-lang/futures-rs |
+| futures-util | 0.3.34 | MIT OR Apache-2.0 | https://github.com/rust-lang/futures-rs |
+| gethostname | 1.1.0 | Apache-2.0 | https://codeberg.org/swsnr/gethostname.rs.git |
+| getrandom | 0.2.17 | MIT OR Apache-2.0 | https://github.com/rust-random/getrandom |
+| getrandom | 0.3.4 | MIT OR Apache-2.0 | https://github.com/rust-random/getrandom |
+| gif | 0.14.2 | MIT OR Apache-2.0 | https://github.com/image-rs/image-gif |
+| glifo | 0.3.0 | Apache-2.0 OR MIT | https://github.com/linebender/vello |
+| glow | 0.17.0 | MIT OR Apache-2.0 OR Zlib | https://github.com/grovesNL/glow |
+| glutin | 0.32.3 | Apache-2.0 | https://github.com/rust-windowing/glutin |
+| glutin-winit | 0.5.0 | MIT | https://github.com/rust-windowing/glutin |
+| glutin_egl_sys | 0.7.1 | Apache-2.0 | https://github.com/rust-windowing/glutin |
+| glutin_glx_sys | 0.6.1 | Apache-2.0 | https://github.com/rust-windowing/glutin |
+| glutin_wgl_sys | 0.6.1 | Apache-2.0 | https://github.com/rust-windowing/glutin |
+| guillotiere | 0.7.0 | MIT/Apache-2.0 | https://github.com/nical/guillotiere |
+| half | 2.7.1 | MIT OR Apache-2.0 | https://github.com/VoidStarKat/half-rs |
+| harfrust | 0.12.0 | MIT | https://github.com/harfbuzz/harfrust |
+| hashbrown | 0.15.5 | MIT OR Apache-2.0 | https://github.com/rust-lang/hashbrown |
+| hashbrown | 0.17.1 | MIT OR Apache-2.0 | https://github.com/rust-lang/hashbrown |
+| hermit-abi | 0.5.3 | MIT OR Apache-2.0 | https://github.com/hermit-os/hermit-rs |
+| http | 1.5.0 | MIT OR Apache-2.0 | https://github.com/hyperium/http |
+| httparse | 1.10.1 | MIT OR Apache-2.0 | https://github.com/seanmonstar/httparse |
+| hybrid-array | 0.4.15 | MIT OR Apache-2.0 | https://github.com/RustCrypto/hybrid-array |
+| iana-time-zone | 0.1.65 | MIT OR Apache-2.0 | https://github.com/strawlab/iana-time-zone |
+| iana-time-zone-haiku | 0.1.2 | MIT OR Apache-2.0 | https://github.com/strawlab/iana-time-zone |
+| icu_collections | 2.4.0 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| icu_locale_core | 2.4.0 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| icu_normalizer | 2.4.0 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| icu_normalizer_data | 2.4.0 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| icu_properties | 2.4.0 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| icu_properties_data | 2.4.0 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| icu_provider | 2.4.0 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| idna | 1.1.0 | MIT OR Apache-2.0 | https://github.com/servo/rust-url/ |
+| idna_adapter | 1.2.2 | Apache-2.0 OR MIT | https://github.com/hsivonen/idna_adapter |
+| image | 0.25.10 | MIT OR Apache-2.0 | https://github.com/image-rs/image |
+| indexmap | 2.14.2 | Apache-2.0 OR MIT | https://github.com/indexmap-rs/indexmap |
+| itertools | 0.15.0 | MIT OR Apache-2.0 | https://github.com/rust-itertools/itertools |
+| itoa | 1.0.18 | MIT OR Apache-2.0 | https://github.com/dtolnay/itoa |
+| jni | 0.22.4 | MIT OR Apache-2.0 | https://github.com/jni-rs/jni-rs |
+| jni-macros | 0.22.4 | MIT OR Apache-2.0 | https://github.com/jni-rs/jni-rs |
+| jni-sys | 0.3.1 | MIT OR Apache-2.0 | https://github.com/jni-rs/jni-sys |
+| jni-sys | 0.4.1 | MIT OR Apache-2.0 | https://github.com/jni-rs/jni-sys |
+| jni-sys-macros | 0.4.1 | MIT OR Apache-2.0 | https://github.com/jni-rs/jni-sys |
+| js-sys | 0.3.107 | MIT OR Apache-2.0 | https://github.com/wasm-bindgen/wasm-bindgen/tree/master/crates/js-sys |
+| kurbo | 0.13.1 | Apache-2.0 OR MIT | https://github.com/linebender/kurbo |
+| libc | 0.2.191 | MIT OR Apache-2.0 | https://github.com/rust-lang/libc |
+| libloading | 0.8.9 | ISC | https://github.com/nagisa/rust_libloading/ |
+| libloading | 0.9.0 | ISC | https://github.com/nagisa/rust_libloading/ |
+| libm | 0.2.16 | MIT | https://github.com/rust-lang/compiler-builtins |
+| libredox | 0.1.25 | MIT | https://gitlab.redox-os.org/redox-os/libredox.git |
+| linebender_resource_handle | 0.1.1 | Apache-2.0 OR MIT | https://github.com/linebender/raw_resource_handle |
+| linux-raw-sys | 0.12.1 | Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT | https://github.com/sunfishcode/linux-raw-sys |
+| linux-raw-sys | 0.4.15 | Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT | https://github.com/sunfishcode/linux-raw-sys |
+| litemap | 0.8.3 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| litrs | 1.0.1 | MIT OR Apache-2.0 | https://github.com/LukasKalbertodt/litrs |
+| lock_api | 0.4.14 | MIT OR Apache-2.0 | https://github.com/Amanieu/parking_lot |
+| log | 0.4.35 | MIT OR Apache-2.0 | https://github.com/rust-lang/log |
+| maybe-owned | 0.3.4 | MIT OR Apache-2.0 | https://github.com/rustonaut/maybe-owned |
+| md-5 | 0.11.0 | MIT OR Apache-2.0 | https://github.com/RustCrypto/hashes |
+| memchr | 2.8.3 | Unlicense OR MIT | https://github.com/BurntSushi/memchr |
+| memmap2 | 0.9.12 | MIT OR Apache-2.0 | https://github.com/RazrFalcon/memmap2-rs |
+| miniz_oxide | 0.8.9 | MIT OR Zlib OR Apache-2.0 | https://github.com/Frommi/miniz_oxide/tree/master/miniz_oxide |
+| miniz_oxide | 0.9.1 | MIT OR Zlib OR Apache-2.0 | https://github.com/Frommi/miniz_oxide/tree/master/miniz_oxide |
+| moxcms | 0.8.1 | BSD-3-Clause OR Apache-2.0 | https://github.com/awxkee/moxcms.git |
+| naga | 30.0.1 | MIT OR Apache-2.0 | https://github.com/gfx-rs/wgpu |
+| naga-types | 30.0.1 | MIT OR Apache-2.0 | https://github.com/gfx-rs/wgpu |
+| ndk | 0.9.0 | MIT OR Apache-2.0 | https://github.com/rust-mobile/ndk |
+| ndk-context | 0.1.1 | MIT OR Apache-2.0 | https://github.com/rust-windowing/android-ndk-rs |
+| ndk-sys | 0.6.0+11769913 | MIT OR Apache-2.0 | https://github.com/rust-mobile/ndk |
+| nohash-hasher | 0.2.0 | Apache-2.0 OR MIT | https://github.com/paritytech/nohash-hasher |
+| nom | 8.0.0 | MIT | https://github.com/rust-bakery/nom |
+| num-conv | 0.2.2 | MIT OR Apache-2.0 | https://github.com/jhpratt/num-conv |
+| num-traits | 0.2.19 | MIT OR Apache-2.0 | https://github.com/rust-num/num-traits |
+| num_enum | 0.7.6 | BSD-3-Clause OR MIT OR Apache-2.0 | https://github.com/illicitonion/num_enum |
+| num_enum_derive | 0.7.6 | BSD-3-Clause OR MIT OR Apache-2.0 | https://github.com/illicitonion/num_enum |
+| objc-sys | 0.3.5 | MIT | https://github.com/madsmtm/objc2 |
+| objc2 | 0.5.3 | MIT | https://github.com/madsmtm/objc2 |
+| objc2 | 0.6.5 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-app-kit | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-app-kit | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-cloud-kit | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-cloud-kit | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-contacts | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-data | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-data | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-foundation | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-graphics | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-image | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-image | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-location | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-text | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-core-video | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-encode | 4.1.0 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-foundation | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-foundation | 0.3.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-io-surface | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-link-presentation | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-metal | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-metal | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-quartz-core | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-quartz-core | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-symbols | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-ui-kit | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-ui-kit | 0.3.2 | Zlib OR Apache-2.0 OR MIT | https://github.com/madsmtm/objc2 |
+| objc2-uniform-type-identifiers | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| objc2-user-notifications | 0.2.2 | MIT | https://github.com/madsmtm/objc2 |
+| once_cell | 1.21.4 | MIT OR Apache-2.0 | https://github.com/matklad/once_cell |
+| option-ext | 0.2.0 | MPL-2.0 | https://github.com/soc/option-ext.git |
+| orbclient | 0.3.55 | MIT | https://gitlab.redox-os.org/redox-os/orbclient |
+| os_pipe | 1.2.3 | MIT | https://github.com/oconnor663/os_pipe.rs |
+| parking_lot | 0.12.5 | MIT OR Apache-2.0 | https://github.com/Amanieu/parking_lot |
+| parking_lot_core | 0.9.12 | MIT OR Apache-2.0 | https://github.com/Amanieu/parking_lot |
+| parlance | 0.1.1 | Apache-2.0 OR MIT | https://github.com/linebender/parley |
+| pdfium-render | 0.9.5 | MIT OR Apache-2.0 | https://github.com/ajrcarey/pdfium-render |
+| peniko | 0.6.1 | Apache-2.0 OR MIT | https://github.com/linebender/peniko |
+| percent-encoding | 2.3.2 | MIT OR Apache-2.0 | https://github.com/servo/rust-url/ |
+| petgraph | 0.8.3 | MIT OR Apache-2.0 | https://github.com/petgraph/petgraph |
+| pin-project | 1.1.13 | Apache-2.0 OR MIT | https://github.com/taiki-e/pin-project |
+| pin-project-internal | 1.1.13 | Apache-2.0 OR MIT | https://github.com/taiki-e/pin-project |
+| pin-project-lite | 0.2.17 | Apache-2.0 OR MIT | https://github.com/taiki-e/pin-project-lite |
+| piston-float | 1.0.1 | MIT | https://github.com/pistondevelopers/float.git |
+| plain | 0.2.3 | MIT/Apache-2.0 | https://github.com/randomites/plain |
+| png | 0.18.1 | MIT OR Apache-2.0 | https://github.com/image-rs/image-png |
+| poll-promise | 0.3.0 | MIT OR Apache-2.0 | https://github.com/EmbarkStudios/poll-promise |
+| polling | 3.11.0 | Apache-2.0 OR MIT | https://github.com/smol-rs/polling |
+| pollster | 0.4.0 | Apache-2.0/MIT | https://github.com/zesterer/pollster |
+| polycool | 0.4.0 | MIT OR Apache-2.0 | https://github.com/linebender/kurbo |
+| portable-atomic | 1.15.0 | Apache-2.0 OR MIT | https://github.com/taiki-e/portable-atomic |
+| portable-atomic-util | 0.2.8 | Apache-2.0 OR MIT | https://github.com/taiki-e/portable-atomic-util |
+| potential_utf | 0.1.6 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| powerfmt | 0.2.1 | MIT OR Apache-2.0 | https://github.com/jhpratt/powerfmt |
+| proc-macro-crate | 3.5.0 | MIT OR Apache-2.0 | https://github.com/bkchr/proc-macro-crate |
+| proc-macro2 | 1.0.107 | MIT OR Apache-2.0 | https://github.com/dtolnay/proc-macro2 |
+| profiling | 1.0.18 | MIT OR Apache-2.0 | https://github.com/aclysma/profiling |
+| pxfm | 0.1.30 | BSD-3-Clause OR Apache-2.0 | https://github.com/awxkee/pxfm |
+| quick-error | 2.0.1 | MIT/Apache-2.0 | http://github.com/tailhook/quick-error |
+| quick-xml | 0.41.0 | MIT | https://github.com/tafia/quick-xml |
+| quote | 1.0.47 | MIT OR Apache-2.0 | https://github.com/dtolnay/quote |
+| r-efi | 5.3.0 | MIT OR Apache-2.0 OR LGPL-2.1-or-later | https://github.com/r-efi/r-efi |
+| raw-window-handle | 0.6.2 | MIT OR Apache-2.0 OR Zlib | https://github.com/rust-windowing/raw-window-handle |
+| read-fonts | 0.41.0 | MIT OR Apache-2.0 | https://github.com/googlefonts/fontations |
+| redox_syscall | 0.4.1 | MIT | https://gitlab.redox-os.org/redox-os/syscall |
+| redox_syscall | 0.5.18 | MIT | https://gitlab.redox-os.org/redox-os/syscall |
+| redox_syscall | 0.9.5 | MIT | https://gitlab.redox-os.org/redox-os/kernel |
+| redox_users | 0.5.3 | MIT | https://gitlab.redox-os.org/redox-os/users |
+| renderdoc-sys | 1.1.0 | MIT OR Apache-2.0 | https://github.com/ebkalderon/renderdoc-rs |
+| rfd | 0.17.2 | MIT | https://github.com/PolyMeilex/rfd |
+| ring | 0.17.14 | Apache-2.0 AND ISC | https://github.com/briansmith/ring |
+| roxmltree | 0.21.2 | MIT OR Apache-2.0 | https://github.com/RazrFalcon/roxmltree |
+| rustc-hash | 1.1.0 | Apache-2.0/MIT | https://github.com/rust-lang-nursery/rustc-hash |
+| rustc-hash | 2.1.3 | Apache-2.0 OR MIT | https://github.com/rust-lang/rustc-hash |
+| rustix | 0.38.44 | Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT | https://github.com/bytecodealliance/rustix |
+| rustix | 1.1.6 | Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT | https://github.com/bytecodealliance/rustix |
+| rustls | 0.23.46 | Apache-2.0 OR ISC OR MIT | https://github.com/rustls/rustls |
+| rustls-pki-types | 1.15.1 | MIT OR Apache-2.0 | https://github.com/rustls/pki-types |
+| rustls-webpki | 0.103.16 | ISC | https://github.com/rustls/webpki |
+| rustversion | 1.0.23 | MIT OR Apache-2.0 | https://github.com/dtolnay/rustversion |
+| scoped-tls | 1.0.1 | MIT/Apache-2.0 | https://github.com/alexcrichton/scoped-tls |
+| scopeguard | 1.2.0 | MIT OR Apache-2.0 | https://github.com/bluss/scopeguard |
+| self_cell | 1.3.0 | Apache-2.0 OR GPL-2.0-only | https://github.com/Voultapher/self_cell |
+| send_wrapper | 0.6.0 | MIT/Apache-2.0 | https://github.com/thk1/send_wrapper |
+| serde | 1.0.229 | MIT OR Apache-2.0 | https://github.com/serde-rs/serde |
+| serde_core | 1.0.229 | MIT OR Apache-2.0 | https://github.com/serde-rs/serde |
+| serde_derive | 1.0.229 | MIT OR Apache-2.0 | https://github.com/serde-rs/serde |
+| serde_json | 1.0.154 | MIT OR Apache-2.0 | https://github.com/serde-rs/json |
+| simd-adler32 | 0.3.10 | MIT | https://github.com/mcountryman/simd-adler32 |
+| simd_cesu8 | 1.2.0 | Apache-2.0 OR MIT | https://github.com/seancroach/simd_cesu8 |
+| simdutf8 | 0.1.5 | MIT OR Apache-2.0 | https://github.com/rusticstuff/simdutf8 |
+| skrifa | 0.44.0 | MIT OR Apache-2.0 | https://github.com/googlefonts/fontations |
+| slab | 0.4.12 | MIT | https://github.com/tokio-rs/slab |
+| slotmap | 1.1.1 | Zlib | https://github.com/orlp/slotmap |
+| smallvec | 1.16.4 | MIT OR Apache-2.0 | https://github.com/servo/rust-smallvec |
+| smithay-client-toolkit | 0.19.2 | MIT | https://github.com/smithay/client-toolkit |
+| smithay-client-toolkit | 0.20.0 | MIT | https://github.com/smithay/client-toolkit |
+| smithay-clipboard | 0.7.3 | MIT | https://github.com/smithay/smithay-clipboard |
+| smol_str | 0.2.2 | MIT OR Apache-2.0 | https://github.com/rust-analyzer/smol_str |
+| stable_deref_trait | 1.2.1 | MIT OR Apache-2.0 | https://github.com/storyyeller/stable_deref_trait |
+| static_assertions | 1.1.0 | MIT OR Apache-2.0 | https://github.com/nvzqz/static-assertions-rs |
+| subtle | 2.6.1 | BSD-3-Clause | https://github.com/dalek-cryptography/subtle |
+| syn | 2.0.119 | MIT OR Apache-2.0 | https://github.com/dtolnay/syn |
+| syn | 3.0.9 | MIT OR Apache-2.0 | https://github.com/dtolnay/syn |
+| synstructure | 0.14.0 | MIT | https://github.com/mystor/synstructure |
+| sys-locale | 0.3.2 | MIT OR Apache-2.0 | https://github.com/1Password/sys-locale |
+| thiserror | 1.0.69 | MIT OR Apache-2.0 | https://github.com/dtolnay/thiserror |
+| thiserror | 2.0.21 | MIT OR Apache-2.0 | https://github.com/dtolnay/thiserror |
+| thiserror-impl | 1.0.69 | MIT OR Apache-2.0 | https://github.com/dtolnay/thiserror |
+| thiserror-impl | 2.0.21 | MIT OR Apache-2.0 | https://github.com/dtolnay/thiserror |
+| tiff | 0.11.3 | MIT | https://github.com/image-rs/image-tiff |
+| time | 0.3.55 | MIT OR Apache-2.0 | https://github.com/time-rs/time |
+| time-core | 0.1.9 | MIT OR Apache-2.0 | https://github.com/time-rs/time |
+| time-macros | 0.2.32 | MIT OR Apache-2.0 | https://github.com/time-rs/time |
+| tinystr | 0.8.5 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| tokio | 1.54.1 | MIT | https://github.com/tokio-rs/tokio |
+| toml_datetime | 1.1.2+spec-1.1.0 | MIT OR Apache-2.0 | https://github.com/toml-rs/toml |
+| toml_edit | 0.25.17+spec-1.1.0 | MIT OR Apache-2.0 | https://github.com/toml-rs/toml |
+| toml_parser | 1.1.5+spec-1.1.0 | MIT OR Apache-2.0 | https://github.com/toml-rs/toml |
+| tracing | 0.1.44 | MIT | https://github.com/tokio-rs/tracing |
+| tracing-core | 0.1.36 | MIT | https://github.com/tokio-rs/tracing |
+| tree_magic_mini | 3.2.2 | MIT | https://github.com/mbrubeck/tree_magic/ |
+| type-map | 0.5.1 | MIT/Apache-2.0 | https://github.com/kardeiz/type-map |
+| typenum | 1.20.1 | MIT OR Apache-2.0 | https://github.com/paholg/typenum |
+| unicode-bidi | 0.3.18 | MIT OR Apache-2.0 | https://github.com/servo/unicode-bidi |
+| unicode-general-category | 1.1.0 | Apache-2.0 | https://github.com/yeslogic/unicode-general-category |
+| unicode-ident | 1.0.27 | (MIT OR Apache-2.0) AND Unicode-3.0 | https://github.com/dtolnay/unicode-ident |
+| unicode-properties | 0.1.5 | (MIT OR Apache-2.0) AND Unicode-3.0 | https://github.com/unicode-rs/unicode-properties |
+| unicode-script | 0.5.9 | MIT OR Apache-2.0 | https://github.com/unicode-rs/unicode-script |
+| unicode-segmentation | 1.13.3 | MIT OR Apache-2.0 | https://github.com/unicode-rs/unicode-segmentation |
+| unicode-width | 0.2.3 | MIT OR Apache-2.0 | https://github.com/unicode-rs/unicode-width |
+| untrusted | 0.9.0 | ISC | https://github.com/briansmith/untrusted |
+| ureq | 3.5.0 | MIT OR Apache-2.0 | https://github.com/algesten/ureq |
+| ureq-proto | 0.6.5 | MIT OR Apache-2.0 | https://github.com/algesten/ureq-proto |
+| url | 2.5.8 | MIT OR Apache-2.0 | https://github.com/servo/rust-url |
+| utf16string | 0.2.0 | MIT OR Apache-2.0 | https://github.com/getsentry/utf16string |
+| utf8-zero | 0.8.1 | MIT OR Apache-2.0 | https://github.com/algesten/utf8-zero |
+| utf8_iter | 1.1.0 | Apache-2.0 OR MIT | https://github.com/hsivonen/utf8_iter |
+| utf_types | 1.0.0 | Apache-2.0 OR MIT | https://github.com/hsivonen/utf_types |
+| uuid | 1.29.0 | Apache-2.0 OR MIT | https://github.com/uuid-rs/uuid |
+| vecmath | 1.0.0 | MIT | https://github.com/pistondevelopers/vecmath.git |
+| vello_common | 0.2.0 | Apache-2.0 OR MIT | https://github.com/linebender/vello |
+| vello_cpu | 0.2.0 | Apache-2.0 OR MIT | https://github.com/linebender/vello |
+| wasi | 0.11.1+wasi-snapshot-preview1 | Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT | https://github.com/bytecodealliance/wasi |
+| wasip2 | 1.0.4+wasi-0.2.12 | Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT | https://github.com/bytecodealliance/wasi-rs |
+| wasm-bindgen | 0.2.130 | MIT OR Apache-2.0 | https://github.com/wasm-bindgen/wasm-bindgen |
+| wasm-bindgen-futures | 0.4.80 | MIT OR Apache-2.0 | https://github.com/wasm-bindgen/wasm-bindgen/tree/master/crates/futures |
+| wasm-bindgen-macro | 0.2.130 | MIT OR Apache-2.0 | https://github.com/wasm-bindgen/wasm-bindgen/tree/master/crates/macro |
+| wasm-bindgen-macro-support | 0.2.130 | MIT OR Apache-2.0 | https://github.com/wasm-bindgen/wasm-bindgen/tree/main/crates/macro-support |
+| wasm-bindgen-shared | 0.2.130 | MIT OR Apache-2.0 | https://github.com/wasm-bindgen/wasm-bindgen/tree/master/crates/shared |
+| wayland-backend | 0.3.17 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-client | 0.31.15 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-csd-frame | 0.3.0 | MIT | https://github.com/rust-windowing/wayland-csd-frame |
+| wayland-cursor | 0.31.14 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-protocols | 0.32.13 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-protocols-experimental | 20250721.0.1 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-protocols-misc | 0.3.12 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-protocols-plasma | 0.3.12 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-protocols-wlr | 0.3.12 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-scanner | 0.31.11 | MIT | https://github.com/smithay/wayland-rs |
+| wayland-sys | 0.31.11 | MIT | https://github.com/smithay/wayland-rs |
+| web-sys | 0.3.107 | MIT OR Apache-2.0 | https://github.com/wasm-bindgen/wasm-bindgen/tree/master/crates/web-sys |
+| web-time | 1.1.0 | MIT OR Apache-2.0 | https://github.com/daxpedda/web-time |
+| webbrowser | 1.2.6 | MIT OR Apache-2.0 | https://github.com/amodm/webbrowser-rs |
+| webpki-roots | 1.0.11 | CDLA-Permissive-2.0 | https://github.com/rustls/webpki-roots |
+| weezl | 0.1.12 | MIT OR Apache-2.0 | https://github.com/image-rs/weezl |
+| wgpu | 30.0.1 | MIT OR Apache-2.0 | https://github.com/gfx-rs/wgpu |
+| wgpu-core | 30.0.1 | MIT OR Apache-2.0 | https://github.com/gfx-rs/wgpu |
+| wgpu-core-deps-windows-linux-android | 30.0.1 | MIT OR Apache-2.0 | https://github.com/gfx-rs/wgpu |
+| wgpu-hal | 30.0.1 | MIT OR Apache-2.0 | https://github.com/gfx-rs/wgpu |
+| wgpu-naga-bridge | 30.0.1 | MIT OR Apache-2.0 | https://github.com/gfx-rs/wgpu |
+| wgpu-types | 30.0.1 | MIT OR Apache-2.0 | https://github.com/gfx-rs/wgpu |
+| widestring | 1.2.1 | MIT OR Apache-2.0 | https://github.com/VoidStarKat/widestring-rs |
+| windows | 0.62.2 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-collections | 0.3.2 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-core | 0.62.2 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-future | 0.3.2 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-implement | 0.60.2 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-interface | 0.59.3 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-link | 0.2.1 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-numerics | 0.3.1 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-result | 0.4.1 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-strings | 0.5.1 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-sys | 0.52.0 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-sys | 0.59.0 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-sys | 0.61.2 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-targets | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows-threading | 0.2.1 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows_aarch64_gnullvm | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows_aarch64_msvc | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows_i686_gnu | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows_i686_gnullvm | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows_i686_msvc | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows_x86_64_gnu | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows_x86_64_gnullvm | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| windows_x86_64_msvc | 0.52.6 | MIT OR Apache-2.0 | https://github.com/microsoft/windows-rs |
+| winit | 0.30.13 | Apache-2.0 | https://github.com/rust-windowing/winit |
+| winnow | 1.0.4 | MIT | https://github.com/winnow-rs/winnow |
+| wit-bindgen | 0.57.1 | Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT | https://github.com/bytecodealliance/wit-bindgen |
+| wl-clipboard-rs | 0.9.5 | MIT OR Apache-2.0 | https://github.com/YaLTeR/wl-clipboard-rs |
+| writeable | 0.6.4 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| x11-dl | 2.21.0 | MIT | https://github.com/AltF02/x11-rs.git |
+| x11rb | 0.13.2 | MIT OR Apache-2.0 | https://github.com/psychon/x11rb |
+| x11rb-protocol | 0.13.2 | MIT OR Apache-2.0 | https://github.com/psychon/x11rb |
+| xcb | 1.7.1 | MIT | https://github.com/rust-x-bindings/rust-xcb |
+| xcursor | 0.3.11 | MIT | https://github.com/esposm03/xcursor-rs |
+| xkbcommon-dl | 0.4.2 | MIT | https://github.com/rust-windowing/xkbcommon-dl |
+| xkeysym | 0.2.1 | MIT OR Apache-2.0 OR Zlib | https://github.com/notgull/xkeysym |
+| yeslogic-fontconfig-sys | 6.0.1 | MIT | https://github.com/yeslogic/fontconfig-rs |
+| yoke | 0.8.4 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| yoke-derive | 0.8.4 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| zerocopy | 0.8.63 | BSD-2-Clause OR Apache-2.0 OR MIT | https://github.com/google/zerocopy |
+| zerocopy-derive | 0.8.63 | BSD-2-Clause OR Apache-2.0 OR MIT | https://github.com/google/zerocopy |
+| zerofrom | 0.1.8 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| zerofrom-derive | 0.1.8 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| zeroize | 1.9.1 | Apache-2.0 OR MIT | https://github.com/RustCrypto/utils |
+| zerotrie | 0.2.5 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| zerovec | 0.11.9 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| zerovec-derive | 0.11.7 | Unicode-3.0 | https://github.com/unicode-org/icu4x |
+| zlib-rs | 0.6.8 | Zlib | https://github.com/trifectatechfoundation/zlib-rs |
+| zmij | 1.0.23 | MIT | https://github.com/dtolnay/zmij |
+| zune-core | 0.5.3 | MIT OR Apache-2.0 OR Zlib | https://github.com/etemesi254/zune-image |
+| zune-jpeg | 0.5.15 | MIT OR Apache-2.0 OR Zlib | https://github.com/etemesi254/zune-image/tree/dev/crates/zune-jpeg |
diff --git a/assets/guide.md b/assets/guide.md
index 8b2ca4a..efdcdb8 100644
--- a/assets/guide.md
+++ b/assets/guide.md
@@ -2,7 +2,7 @@
 
 To use TeXora from a terminal, choose **? > Command-line tool**. To see what this computer has for TeXora, choose **? > System check**.
 
-Open a PDF or a LaTeX file from the start page, or drop one on the window. Choose **New LaTeX presentation** to pick one of eight templates, each with its own colours and style: Classic Green, Midnight, Minimal White, Conference and Sunrise, and three animated ones, Motion Lab, Flipbook and Media Studio, whose slides show animations, GIF frames and a video clip playing. Write your presentation in your own LaTeX editor: TeXora rebuilds the slides every time you save it. Recent files stay on the start page.
+Open a PDF or a LaTeX file from the start page, or drop one on the window. Choose **New LaTeX presentation** to pick one of nine templates, each with its own colours and style: Classic Green, Midnight, Minimal White, Conference and Sunrise, and four animated ones, Motion Lab, Flipbook, Media Studio and Video Guide, whose slides show animations, GIF frames and video clips playing. **Video Guide** explains `\includevideo` slide by slide, with a video and a GIF that play inside the slides. Write your presentation in your own LaTeX editor: TeXora rebuilds the slides every time you save it. Recent files stay on the start page.
 
 ## Giving a talk
 
@@ -85,6 +85,8 @@ TeXora needs TeX Live, MacTeX or MiKTeX installed to compile. It picks pdfLaTeX,
 
 Animations made with the LaTeX **animate** package play on the slide, as in Adobe Acrobat. Those set to `autoplay` start when their slide is shown and stop when you move on; `loop` and `palindrome` work too, at the animation's own speed. Click an animation to play or pause it. In the presenter view, the bar under it has first, previous, play/pause, next and last frame buttons, and the audience sees the same frame.
 
+Videos and GIFs can also play **inside the slide**. GIFs play by themselves; **MP4 playback uses VLC or ffmpeg installed on your computer** (ffmpeg plays inside the slide, VLC in its own window; choose in Settings > Video, which has a Test button). TeXora contains no video decoder and never installs one; when a video needs a player and none is found, it says so, with Get VLC, Get ffmpeg and Copy install command. Write `\usepackage{texoravideo}` and `\includevideo[width=0.5\textwidth]{clip.mp4}` (TeXora finds the package by itself). A second optional argument takes `autoplay`, `loop`, `posterat=25` or `poster=cover.png`. The video must be in the `.tex` file's folder or a folder inside it; if it is in a folder, write the folder name too, as in `{videos/clip.mp4}`. When compiling, TeXora makes one poster per video in a `texora-video` folder, so every PDF viewer shows the poster; in TeXora a click plays or pauses the clip and another slide stops it. Files that are not videos, files outside the presentation's folder, and videos not found show a message over the poster.
+
 Video clips added with `\movie` (multimedia) or `\includemedia` (media9) show a play button on your screen. Click the clip to play it in your computer's video player; clips set to start by themselves open when their slide is shown while the audience window is open. Keep a `\movie` file in the same folder as the presentation.
 
 ## After the talk
diff --git a/assets/templates/video-1.png b/assets/templates/video-1.png
new file mode 100644
index 0000000..129dc1a
Binary files /dev/null and b/assets/templates/video-1.png differ
diff --git a/assets/templates/video-5.png b/assets/templates/video-5.png
new file mode 100644
index 0000000..a3bf37c
Binary files /dev/null and b/assets/templates/video-5.png differ
diff --git a/assets/templates/video.tex b/assets/templates/video.tex
new file mode 100644
index 0000000..076f5a2
--- /dev/null
+++ b/assets/templates/video.tex
@@ -0,0 +1,273 @@
+%% TeXora template: Video Guide. Navy and gold 16:9 slides that show, and explain, videos and GIFs
+%% playing inside the slides.
+%%
+%% What you need:
+%%   - TeXora. The texoravideo package is built in: TeXora finds it by itself when it compiles, so
+%%     there is no package to install or copy.
+%%   - For MP4 and other videos: VLC or ffmpeg installed on your computer. MP4 playback uses VLC or
+%%     ffmpeg installed on your computer (ffmpeg plays inside the slide and makes posters; VLC plays
+%%     in its own window). GIFs need nothing. TeXora contains no video decoder.
+%%   - In the preamble:  \usepackage{texoravideo}  and  \hypersetup{hidelinks}
+%%   - Your clips: video files (such as MP4) or GIFs, kept in one of two places:
+%%       in the same folder as this .tex file, or in a folder inside it (any name).
+%%     If the clip is in a folder, write the folder name too: {media/clip.mp4}, {videos/clip.mp4}.
+%%     This template brings two, in its media folder: media/sample-video.mp4 and media/sample-loop.gif.
+%%   - If a clip is in neither place, TeXora says so over its poster and under Problems.
+%%
+%% Use:  \includevideo[<graphics options>][<video options>]{<file>}
+%%   <graphics options> go to \includegraphics as they are: width=..., height=..., scale=...
+%%   <video options>: autoplay, loop, posterat=<percent>, poster=<picture>
+%%
+%% When TeXora compiles, it makes each video's poster (a picture of it) in the folder texora-video/:
+%% one poster per video, however often it is used. Every PDF viewer shows the poster; TeXora plays the
+%% clip when you click it.
+%% Change the colours on the \definecolor lines below; everything else follows them.
+% !TEX program = pdflatex
+\documentclass[aspectratio=169]{beamer}
+\usetheme{default}
+\usepackage[T1]{fontenc}
+\usepackage{lmodern}
+\usepackage{booktabs}
+\usepackage{texoravideo}
+\hypersetup{hidelinks}
+\definecolor{navy}{RGB}{22,50,92}
+\definecolor{gold}{RGB}{233,180,76}
+\definecolor{mist}{RGB}{238,242,248}
+\setbeamercolor{structure}{fg=navy}
+\setbeamercolor{frametitle}{bg=navy,fg=white}
+\setbeamercolor{title}{fg=white}
+\setbeamercolor{subtitle}{fg=gold}
+\setbeamercolor{author}{fg=white}
+\setbeamercolor{institute}{fg=mist}
+\setbeamercolor{date}{fg=mist}
+\setbeamercolor{block title}{bg=gold,fg=navy}
+\setbeamercolor{block body}{bg=mist}
+\setbeamercolor{item}{fg=gold!80!black}
+\setbeamertemplate{blocks}[rounded][shadow=false]
+\setbeamertemplate{navigation symbols}{}
+\setbeamertemplate{itemize items}[circle]
+\setbeamertemplate{frametitle}{%
+  \nointerlineskip\begin{beamercolorbox}[wd=\paperwidth,ht=3ex,dp=1.4ex,leftskip=1.2em]{frametitle}%
+    \usebeamerfont{frametitle}\insertframetitle\end{beamercolorbox}}
+\setbeamertemplate{footline}{%
+  \leavevmode\hbox{\begin{beamercolorbox}[wd=\paperwidth,ht=2.2ex,dp=1ex,right]{frametitle}%
+    \insertframenumber\,/\,\inserttotalframenumber\hspace*{1.5em}\end{beamercolorbox}}}
+\setbeameroption{show notes on second screen=right}
+
+% Code on a slide, in a small typewriter font.
+\newcommand{\code}[1]{{\small\ttfamily #1}}
+
+\title{Video Guide}
+\subtitle{Videos and GIFs that play inside your slides}
+\author{Your Name}
+\institute{Your Institution}
+\date{\today}
+
+\begin{document}
+
+{\setbeamercolor{background canvas}{bg=navy}
+\begin{frame}[plain]
+  \vfill
+  \begin{center}
+    {\usebeamerfont{title}\usebeamercolor[fg]{title}\Huge\inserttitle\par}
+    \vspace{0.6em}
+    {\usebeamercolor[fg]{subtitle}\Large\insertsubtitle\par}
+    \vspace{2em}
+    {\usebeamercolor[fg]{author}\insertauthor\par}
+    {\usebeamercolor[fg]{institute}\small\insertinstitute\quad\insertdate\par}
+  \end{center}
+  \vfill
+\end{frame}}
+\note{This deck explains itself: each slide shows one way to use \textbackslash includevideo. Replace the clips in the media folder with your own.}
+
+\begin{frame}[fragile]{What you need}
+  \begin{columns}[T]
+    \begin{column}{0.5\textwidth}
+      \begin{itemize}
+        \item \textbf{TeXora}: the \code{texoravideo} package is built in.
+        \item \textbf{For MP4}: VLC or ffmpeg installed on your computer. GIFs need nothing.
+        \item \textbf{Two lines} in the preamble:
+      \end{itemize}
+\begin{semiverbatim}\small
+\textbackslash{}usepackage\{texoravideo\}
+\textbackslash{}hypersetup\{hidelinks\}
+\end{semiverbatim}
+    \end{column}
+    \begin{column}{0.46\textwidth}
+      \begin{itemize}
+        \item \textbf{Your clips}: MP4 (or another video file), or GIF.
+        \item Kept in \textbf{this file's folder}, or in a \textbf{folder inside it}.
+        \item \textbf{Compile in TeXora}: it makes one poster per video in \code{texora-video/}.
+      \end{itemize}
+    \end{column}
+  \end{columns}
+\end{frame}
+\note{GIFs play by themselves. MP4 playback uses VLC or ffmpeg installed on your computer: choose it in Settings, Video. TeXora contains no video decoder and never installs one.}
+
+\begin{frame}[fragile]{A video}
+  \begin{columns}[c]
+    \begin{column}{0.55\textwidth}
+      \includevideo[width=\linewidth][posterat=30]{media/sample-video.mp4}
+    \end{column}
+    \begin{column}{0.42\textwidth}
+\begin{semiverbatim}\footnotesize
+\textbackslash{}includevideo
+  [width=\textbackslash{}linewidth]
+  [posterat=30]
+  \{media/sample-video.mp4\}
+\end{semiverbatim}
+      \begin{itemize}
+        \item \textbf{Click} to play, click again to pause.
+        \item \code{posterat=30}: the poster is the picture 30\,\% of the way in.
+      \end{itemize}
+    \end{column}
+  \end{columns}
+\end{frame}
+\note{Click the clip to play it. Going to another slide stops it.}
+
+\begin{frame}[fragile]{A GIF that loops}
+  \begin{columns}[c]
+    \begin{column}{0.55\textwidth}
+      \centering
+      \includevideo[height=4.2cm][loop,autoplay]{media/sample-loop.gif}
+    \end{column}
+    \begin{column}{0.42\textwidth}
+\begin{semiverbatim}\footnotesize
+\textbackslash{}includevideo
+  [height=4.2cm]
+  [loop,autoplay]
+  \{media/sample-loop.gif\}
+\end{semiverbatim}
+      \begin{itemize}
+        \item GIFs work the same way as videos: no splitting into frames.
+        \item \code{autoplay} starts it with the slide; \code{loop} plays it again and again.
+      \end{itemize}
+    \end{column}
+  \end{columns}
+\end{frame}
+
+\begin{frame}{Both at once}
+  \begin{columns}[c]
+    \begin{column}{0.48\textwidth}
+      \includevideo[width=\linewidth]{media/sample-video.mp4}
+      \par\smallskip\centering\small A video: click to play
+    \end{column}
+    \begin{column}{0.48\textwidth}
+      \centering
+      \includevideo[width=0.85\linewidth][loop,autoplay]{media/sample-loop.gif}
+      \par\smallskip\small A GIF that starts by itself
+    \end{column}
+  \end{columns}
+\end{frame}
+\note{Any number of clips can share a slide. Each one plays and pauses on its own.}
+
+\begin{frame}{The two optional arguments}
+  \centering
+  \code{\textbackslash includevideo[\emph{graphics options}][\emph{video options}]\{\emph{file}\}}
+  \par\bigskip
+  \begin{tabular}{@{}ll@{}}
+    \toprule
+    \textbf{Graphics options} & go to \code{\textbackslash includegraphics} as they are \\
+    \code{width=0.5\textbackslash textwidth} & the size on the slide \\
+    \code{height=5cm}, \code{scale=0.5} & \\
+    \midrule
+    \textbf{Video options} & \\
+    \code{autoplay} & plays as soon as the slide is shown \\
+    \code{loop} & starts again at the end \\
+    \code{posterat=25} & poster from 25\,\% of the way in (default: first frame) \\
+    \code{poster=cover.png} & your own poster picture \\
+    \bottomrule
+  \end{tabular}
+\end{frame}
+
+\begin{frame}{Where clips can be}
+  \begin{columns}[T]
+    \begin{column}{0.48\textwidth}
+      \begin{block}{In the same folder as the .tex file}
+        \code{talk.tex}\\
+        \code{clip.mp4}\par\smallskip
+        \code{\textbackslash includevideo\{clip.mp4\}}
+      \end{block}
+    \end{column}
+    \begin{column}{0.48\textwidth}
+      \begin{block}{In a folder inside it}
+        \code{talk.tex}\\
+        \code{videos/clip.mp4}\par\smallskip
+        \code{\textbackslash includevideo\{videos/clip.mp4\}}
+      \end{block}
+    \end{column}
+  \end{columns}
+  \par\medskip
+  \begin{itemize}
+    \item Any folder name works. If the clip is in a folder, \textbf{write the folder name too}.
+    \item A clip that is not where its name says: TeXora writes \emph{Video not found} over its
+      poster and under \textbf{Problems}.
+  \end{itemize}
+\end{frame}
+\note{The path is read exactly as written, from the folder of the .tex file.}
+
+\begin{frame}{Posters}
+  \begin{block}{What every viewer shows}
+    The poster is an ordinary picture, so every PDF viewer shows it. Only TeXora plays the clip;
+    other viewers do nothing when it is clicked.
+  \end{block}
+  \begin{itemize}
+    \item TeXora makes \textbf{one poster per video} in \code{texora-video/} when it compiles, however
+      often the video is used, and makes it again only when the clip changes.
+    \item A video used several times has one \code{posterat}: the first one given counts.
+    \item \code{poster=cover.png} uses your picture. If that file is missing, a picture of the clip
+      is used instead.
+    \item Keep \code{texora-video/} beside the PDF, so the clips still play when you open it later.
+  \end{itemize}
+\end{frame}
+
+\begin{frame}{Overlays keep playing}
+  \begin{columns}[c]
+    \begin{column}{0.5\textwidth}
+      \includevideo[width=\linewidth]{media/sample-video.mp4}
+    \end{column}
+    \begin{column}{0.46\textwidth}
+      \begin{itemize}
+        \item Start the clip, then go on to the next step.\pause
+        \item It keeps playing on every step of the same slide.\pause
+        \item Another slide stops it.
+      \end{itemize}
+    \end{column}
+  \end{columns}
+\end{frame}
+\note{Steps made with \textbackslash pause, \textbackslash only or overlays count as the same slide.}
+
+\begin{frame}{If a clip does not play}
+  TeXora writes the reason over the poster on your screen (never on the audience's), and lists it
+  under \textbf{Problems} at the line of the \code{\textbackslash includevideo}.
+  \par\medskip
+  \begin{tabular}{@{}ll@{}}
+    \toprule
+    \textbf{Message} & \textbf{What to do} \\
+    \midrule
+    Video not found & check the name, and the folder name if it is in a folder \\
+    Not a video & use a video file or a GIF \\
+    Needs VLC or ffmpeg & install one: \emph{Get VLC} or \emph{Get ffmpeg} \\
+    Not played & keep it inside the presentation's folder \\
+    \bottomrule
+  \end{tabular}
+  \par\medskip
+  \small Names may have spaces and accents, but not \code{\%} or \code{\#}.
+  Web addresses, absolute paths and \code{..} are not played.
+\end{frame}
+
+\begin{frame}{Your turn}
+  \begin{enumerate}
+    \item Put your clips in this file's folder, or in a folder inside it.
+    \item Change the names in the \code{\textbackslash includevideo} lines, with the folder if there is one.
+    \item Save: TeXora compiles, makes the posters and the clips are ready to play.
+  \end{enumerate}
+  \par\bigskip
+  \begin{block}{Good to know}
+    GIFs play by themselves; MP4 playback uses VLC or ffmpeg installed on your computer. Sound is not
+    played yet. With ffmpeg, clips play on your screen and the audience's at the same time.
+  \end{block}
+\end{frame}
+\note{Thank the audience and invite questions.}
+
+\end{document}
diff --git a/assets/templates/video/sample-loop.gif b/assets/templates/video/sample-loop.gif
new file mode 100644
index 0000000..230a41c
Binary files /dev/null and b/assets/templates/video/sample-loop.gif differ
diff --git a/assets/templates/video/sample-video.mp4 b/assets/templates/video/sample-video.mp4
new file mode 100644
index 0000000..a61b782
Binary files /dev/null and b/assets/templates/video/sample-video.mp4 differ
diff --git a/assets/test/video/clip_baseline.mp4 b/assets/test/video/clip_baseline.mp4
new file mode 100644
index 0000000..64c34ab
Binary files /dev/null and b/assets/test/video/clip_baseline.mp4 differ
diff --git a/assets/test/video/hevc.mp4 b/assets/test/video/hevc.mp4
new file mode 100644
index 0000000..9f4c56e
Binary files /dev/null and b/assets/test/video/hevc.mp4 differ
diff --git a/assets/test/video/test.gif b/assets/test/video/test.gif
new file mode 100644
index 0000000..a76f1af
Binary files /dev/null and b/assets/test/video/test.gif differ
diff --git a/assets/test/video/test.mp4 b/assets/test/video/test.mp4
new file mode 100644
index 0000000..d35f923
Binary files /dev/null and b/assets/test/video/test.mp4 differ
diff --git a/assets/test/video/test.txt b/assets/test/video/test.txt
new file mode 100644
index 0000000..b1f1f09
--- /dev/null
+++ b/assets/test/video/test.txt
@@ -0,0 +1 @@
+This is not a video.
diff --git a/assets/tex/texoravideo.sty b/assets/tex/texoravideo.sty
new file mode 100644
index 0000000..e7dc3e3
--- /dev/null
+++ b/assets/tex/texoravideo.sty
@@ -0,0 +1,73 @@
+%% texoravideo.sty -- video and GIFs in LaTeX slides, played by TeXora.
+%%
+%% TeXora ships this package and finds it by itself when it compiles; there is no package to install or
+%% copy. GIFs play in TeXora by themselves; MP4 playback uses VLC or ffmpeg installed on your computer.
+%%
+%%   \usepackage{texoravideo}
+%%   \includevideo[<graphics options>][<video options>]{<file>}
+%%
+%% <graphics options> go to \includegraphics as they are (width=..., height=..., scale=...).
+%% <video options>, read with xkeyval:
+%%   autoplay[=true|false]  play when the slide is shown (default false)
+%%   loop[=true|false]      start again at the end (default false)
+%%   mute[=true|false]      no sound (default false)
+%%   posterat=<percent>     poster from this far into the clip, 0-99 (default 0, the first frame);
+%%                          a video has one poster, so the first posterat given for it counts
+%%   poster=<image>         your own poster picture instead of a frame of the clip
+%%
+%% <file> is read exactly as written, from the presentation's folder: {clip.mp4} is beside the .tex
+%% file, {videos/clip.mp4} is in its videos folder (any folder name inside it works).
+%%
+%% Before LaTeX runs, TeXora finds every \includevideo, checks the file and makes its poster in the
+%% folder texora-video/: one poster per video, named by the MD5 of the path as written, so this
+%% package can name it too. On the page the poster is an ordinary picture, which every PDF viewer
+%% shows; over it is a link to "texora-video:<options>:<path>", which TeXora plays inside the slide.
+%% Other viewers do nothing with such a link (Acrobat may ask about it).
+\NeedsTeXFormat{LaTeX2e}
+\ProvidesPackage{texoravideo}[2026/11/08 v1.0 Video in slides, played by TeXora]
+\RequirePackage{graphicx}
+\RequirePackage{xkeyval}
+\RequirePackage{pdftexcmds}
+\RequirePackage{iftex}
+\RequirePackage{hyperref}
+
+\def\tv@dir{texora-video}
+
+% The MD5 of the path's characters as UTF-8, in capitals, the same in every engine. LuaTeX's
+% \pdf@mdfivesum hashes accented letters differently, so there Lua does it.
+\ifluatex
+  \def\tv@mdfive#1{\directlua{tex.sprint(string.upper(md5.sumhexa("\luaescapestring{\detokenize{#1}}")))}}
+\else
+  \def\tv@mdfive#1{\pdf@mdfivesum{\detokenize{#1}}}
+\fi
+
+\define@boolkey{texoravideo}[tv@]{autoplay}[true]{}
+\define@boolkey{texoravideo}[tv@]{loop}[true]{}
+\define@boolkey{texoravideo}[tv@]{mute}[true]{}
+\define@key{texoravideo}{posterat}{\edef\tv@at{\number\numexpr#1\relax}}
+\define@key{texoravideo}{poster}{\def\tv@poster{#1}}
+
+\NewDocumentCommand\includevideo{O{} O{} m}{%
+  \begingroup
+  \tv@autoplayfalse\tv@loopfalse\tv@mutefalse
+  \def\tv@at{0}\def\tv@poster{}%
+  \setkeys{texoravideo}{#2}%
+  % The path exactly as written, from the presentation's folder.
+  \def\tv@rel{#3}%
+  \edef\tv@relstr{\expandafter\detokenize\expandafter{\tv@rel}}%
+  \edef\tv@hash{\expandafter\tv@mdfive\expandafter{\tv@rel}}%
+  \edef\tv@made{\tv@dir/\tv@hash.jpg}%
+  % Your poster if it exists, else the one TeXora made, else a plain placeholder.
+  \def\tv@image{texoravideo-placeholder.png}%
+  \IfFileExists{\tv@made}{\let\tv@image\tv@made}{}%
+  \ifx\tv@poster\@empty\else
+    \IfFileExists{\tv@poster}{\let\tv@image\tv@poster}%
+      {\PackageWarning{texoravideo}{Poster `\tv@poster' not found; using a frame of the clip}}%
+  \fi
+  \edef\tv@flags{a\iftv@autoplay1\else0\fi l\iftv@loop1\else0\fi m\iftv@mute1\else0\fi p\tv@at}%
+  \hypersetup{hidelinks}%
+  \href{texora-video:\tv@flags:\tv@relstr}{\includegraphics[#1]{\tv@image}}%
+  \endgroup
+}
+
+\endinput
diff --git a/scripts/build-cross.sh b/scripts/build-cross.sh
index b70bf0e..0bcf688 100644
--- a/scripts/build-cross.sh
+++ b/scripts/build-cross.sh
@@ -24,7 +24,7 @@ case "$KIND" in
     python3 scripts/get-linux-libs.py .toolchain/linux-libs
     # glibc 2.31 means it also runs on Linux systems several years old.
     CARGO_ENCODED_RUSTFLAGS="-Lnative=$PWD/.toolchain/linux-libs/$ARCH" cargo zigbuild --release --locked --target "$TRIPLE.2.31"
-    cp "target/$TRIPLE/release/TeXora" "target/$TRIPLE/release/libpdfium.so" README.md CREDITS.md LICENSE assets/TeXora.desktop "$STAGE/$P/"
+    cp "target/$TRIPLE/release/TeXora" "target/$TRIPLE/release/libpdfium.so" README.md CREDITS.md THIRD-PARTY-LICENSES.md LICENSE assets/TeXora.desktop "$STAGE/$P/"
     cp assets/icon.png "$STAGE/$P/TeXora.png"
     # No hidden macOS "._" metadata files in a Linux package.
     COPYFILE_DISABLE=1 tar -C "$STAGE" -czf "$OUT/$P.tar.gz" "$P"
@@ -32,7 +32,7 @@ case "$KIND" in
     ;;
   windows-*)
     cargo zigbuild --release --locked --target "$TRIPLE"
-    cp "target/$TRIPLE/release/TeXora.exe" "target/$TRIPLE/release/pdfium.dll" README.md CREDITS.md LICENSE "$STAGE/$P/"
+    cp "target/$TRIPLE/release/TeXora.exe" "target/$TRIPLE/release/pdfium.dll" README.md CREDITS.md THIRD-PARTY-LICENSES.md LICENSE "$STAGE/$P/"
     # No hidden macOS "._" metadata files in a Windows package.
     (cd "$STAGE" && ditto -c -k --norsrc --noextattr --noqtn --keepParent "$P" "$OUT/$P.zip")
     BIN="$STAGE/$P/TeXora.exe" ; LIB="$STAGE/$P/pdfium.dll" ; ARCHIVE="$P.zip"
diff --git a/scripts/build-mac.sh b/scripts/build-mac.sh
index 1177c1f..82e22cc 100644
--- a/scripts/build-mac.sh
+++ b/scripts/build-mac.sh
@@ -21,7 +21,7 @@ APP="$STAGE/TeXora.app"
 mkdir -p "$APP/Contents/MacOS" "$APP/Contents/Resources"
 cp "target/$TARGET/release/TeXora" "$APP/Contents/MacOS/TeXora"
 cp "target/$TARGET/release/libpdfium.dylib" "$APP/Contents/MacOS/libpdfium.dylib"
-cp README.md CREDITS.md LICENSE "$APP/Contents/Resources/"
+cp README.md CREDITS.md THIRD-PARTY-LICENSES.md LICENSE "$APP/Contents/Resources/"
 cp assets/icon.icns "$APP/Contents/Resources/TeXora.icns"
 cat > "$APP/Contents/Info.plist" <<EOF
 <?xml version="1.0" encoding="UTF-8"?>
diff --git a/scripts/check-no-codecs.sh b/scripts/check-no-codecs.sh
new file mode 100644
index 0000000..29645b7
--- /dev/null
+++ b/scripts/check-no-codecs.sh
@@ -0,0 +1,24 @@
+#!/bin/sh
+# Checks the packages of one version for any video decoder, ffmpeg, VLC or codec library, and stops if
+# one is found. TeXora ships none of these: MP4 playback uses VLC or ffmpeg installed on the computer.
+# Two checks: no such file in any package, and no such code built into any file (a decoder compiled
+# into the program leaves its name inside it, as OpenH264 did). Sample videos inside the program are
+# files, not decoders, so the name x264 writes into every video it makes is not searched for.
+# Usage: scripts/check-no-codecs.sh dist/<version>
+set -eu
+OUT="$1"
+WORK=$(mktemp -d)
+for f in "$OUT"/*.zip; do [ -e "$f" ] && unzip -q -o "$f" -d "$WORK/$(basename "$f")"; done
+for f in "$OUT"/*.tar.gz; do [ -e "$f" ] && mkdir -p "$WORK/$(basename "$f")" && tar -xzf "$f" -C "$WORK/$(basename "$f")"; done
+FILES=$(find "$WORK" -type f | wc -l | tr -d ' ')
+NAMES=$(find "$WORK" -type f | grep -iE '/(lib)?(ffmpeg|ffprobe|avcodec|avformat|avutil|swscale|vlc|libvlc|libvlccore|openh264|x264|x265|dav1d|de265|vpx)[^/]*$' || true)
+# The guide and licence pages may mention these names in words; only programs and libraries are searched.
+INSIDE=$(find "$WORK" -type f ! -name '*.md' ! -name '*.html' ! -name '*.js' ! -name '*.txt' ! -name '*.css' ! -name '*.json' ! -name '*.svg' -exec grep -l -a -E 'OpenH264|WelsDecoder|WelsCreateDecoder|libavcodec|avcodec_send_packet|libvlc_new' {} + 2>/dev/null || true)
+rm -rf "$WORK"
+if [ -n "$NAMES$INSIDE" ]; then
+  echo "STOP: a video decoder or codec is in the packages of $OUT:"
+  [ -n "$NAMES" ] && echo "$NAMES" | sed "s|$WORK/||"
+  [ -n "$INSIDE" ] && echo "$INSIDE" | sed "s|$WORK/||; s|$| (built in)|"
+  exit 1
+fi
+echo "OK: $FILES files in the packages of $OUT; no ffmpeg, VLC, decoder or codec library, as a file or built in."
diff --git a/scripts/release.sh b/scripts/release.sh
index 2ba7fb1..0a670f2 100644
--- a/scripts/release.sh
+++ b/scripts/release.sh
@@ -12,6 +12,8 @@ mkdir -p "$OUT"
 
 echo "== Making icons from assets/icon.png"
 python3 scripts/make-icons.py
+echo "== No video decoder or codec inside, and the licence list up to date"
+python3 scripts/third-party.py
 echo "== Testing the code"
 cargo test --locked
 echo "== Keeps working while hidden"
@@ -37,6 +39,9 @@ echo "== Linux .deb installers"
 python3 scripts/make-deb.py linux-x64
 python3 scripts/make-deb.py linux-arm64
 
+echo "== No ffmpeg, VLC or codec library in any package"
+sh scripts/check-no-codecs.sh "$OUT"
+
 (cd "$OUT" && shasum -a 256 TeXora-*.zip TeXora-*.tar.gz TeXora-*.dmg texora_*.deb > SHA256SUMS.txt)
 
 
diff --git a/scripts/third-party.py b/scripts/third-party.py
new file mode 100644
index 0000000..3d88ded
--- /dev/null
+++ b/scripts/third-party.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+"""Writes THIRD-PARTY-LICENSES.md: every library built into the program, with its version, licence and
+home page, read from Cargo's own records (the libraries the program uses at run time, on any of Mac,
+Linux and Windows). Also checks that none of them is a video decoder or codec: TeXora contains none,
+and plays MP4 through VLC or ffmpeg installed on the person's computer.
+
+Usage, from the project folder:  python3 scripts/third-party.py [--check]
+--check only checks for codecs and exits 1 if one is found.
+"""
+import json
+import pathlib
+import subprocess
+import sys
+
+# Names that must never be inside TeXora: video decoders, encoders and players.
+FORBIDDEN = ("openh264", "ffmpeg", "x264", "x265", "libvlc", "vlc", "gstreamer", "dav1d", "libde265", "mp4", "avcodec", "rav1e", "vpx")
+
+meta = json.loads(subprocess.run(["cargo", "metadata", "--format-version", "1", "--locked"], capture_output=True, text=True, check=True).stdout)
+packages = {p["id"]: p for p in meta["packages"]}
+nodes = {n["id"]: n for n in meta["resolve"]["nodes"]}
+root = meta["resolve"]["root"]
+
+# Libraries reached through normal dependencies only (not build tools or test helpers).
+seen, todo = set(), [root]
+while todo:
+    pid = todo.pop()
+    if pid in seen:
+        continue
+    seen.add(pid)
+    for d in nodes[pid]["deps"]:
+        if any(k["kind"] is None for k in d["dep_kinds"]):
+            todo.append(d["pkg"])
+seen.discard(root)
+
+libs = sorted((packages[i] for i in seen), key=lambda p: (p["name"].lower(), p["version"]))
+bad = [p["name"] for p in libs if any(f == p["name"].lower() or p["name"].lower().startswith(f + "-") or p["name"].lower().startswith(f + "_") for f in FORBIDDEN)]
+if bad:
+    print("STOP: video decoder or codec libraries found: " + ", ".join(sorted(set(bad))))
+    sys.exit(1)
+if "--check" in sys.argv:
+    print(f"OK: {len(libs)} libraries, no video decoder or codec among them.")
+    sys.exit(0)
+
+name = packages[root]["name"]
+app = "TeXora"
+lines = [
+    "# Third-party licences",
+    "",
+    f"{app} is built from the libraries below; each keeps its own licence. This list is made by",
+    "`scripts/third-party.py` from Cargo's records, so it matches the program exactly.",
+    "",
+    "## Not included",
+    "",
+    f"{app} contains **no video decoder, encoder or player**: no H.264 or other codec, no ffmpeg, no VLC",
+    "or libvlc. GIFs are decoded by the `image` library. **MP4 playback uses VLC or ffmpeg installed on",
+    f"your computer**, started as separate programs; {app} never downloads, installs, ships or updates them.",
+    "ffmpeg and VLC have their own licences (LGPL/GPL), which apply to the copies you install.",
+    "",
+    "## Shipped beside the program",
+    "",
+    "| Component | Licence | Source |",
+    "|---|---|---|",
+    "| PDFium (prebuilt by bblanchon/pdfium-binaries) | BSD-3-Clause and Apache-2.0 | https://github.com/bblanchon/pdfium-binaries |",
+    "| Inter font (Rasmus Andersson) | SIL Open Font License 1.1 | https://rsms.me/inter/ |",
+    "| Hack and Ubuntu Light fonts (inside egui) | MIT; Ubuntu Font Licence | https://github.com/emilk/egui |",
+    "",
+    f"## Rust libraries built into the program ({len(libs)})",
+    "",
+    "| Library | Version | Licence | Source |",
+    "|---|---|---|---|",
+]
+for p in libs:
+    lic = (p.get("license") or p.get("license_file") or "see source").replace("|", "/")
+    src = p.get("repository") or p.get("homepage") or f"https://crates.io/crates/{p['name']}"
+    lines.append(f"| {p['name']} | {p['version']} | {lic} | {src} |")
+pathlib.Path("THIRD-PARTY-LICENSES.md").write_text("\n".join(lines) + "\n")
+print(f"Wrote THIRD-PARTY-LICENSES.md: {len(libs)} libraries, no video decoder or codec.")
diff --git a/src/app.rs b/src/app.rs
index 9591c33..1208975 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -285,6 +285,15 @@ pub struct App {
     pub anim_pending: HashSet<pdf::FrameReq>,
     /// The page whose animations were last started, so a new slide starts its own.
     pub anim_page: Option<usize>,
+    /// texoravideo clips playing or paused on the slide on show; another slide stops them.
+    pub players: Vec<crate::ui_video::Player>,
+    /// The document generation and slide (Beamer frame) the players belong to.
+    pub video_frame: Option<(u64, usize)>,
+    pub player_seq: u64,
+    /// True while the audience window is being drawn: it shows clips but no messages or buttons.
+    pub painting_audience: bool,
+    /// Where a press on a clip began, to tell a click on it.
+    pub video_press: Option<egui::Pos2>,
     /// In the studio, show the slide for the line the cursor is on.
     pub follow_cursor: bool,
     pub tex_checked: Instant,
@@ -353,6 +362,8 @@ impl App {
         let display = displays.iter().position(|d| !d.is_primary).unwrap_or(0);
         let st = Settings::load();
         ctx.set_zoom_factor(st.ui_scale);
+        // Which installed video tool (if any) plays videos that are not GIFs.
+        crate::video::configure(&st.video_player, &st.ffmpeg_path, &st.vlc_path);
         let mut app = App {
             tabs: vec![Tab::blank(1)],
             active: 0,
@@ -448,6 +459,11 @@ impl App {
             anim_cache: HashMap::new(),
             anim_pending: HashSet::new(),
             anim_page: None,
+            players: vec![],
+            video_frame: None,
+            player_seq: 0,
+            painting_audience: false,
+            video_press: None,
             follow_cursor: true,
             tex_checked: Instant::now(),
             search_q: String::new(),
@@ -1062,6 +1078,7 @@ impl App {
     /// Runs the animations of the slide on show. As in Acrobat: a slide's animations that play by
     /// themselves start from the first frame when it is shown, and stop when another slide is shown.
     fn animate(&mut self, ctx: &Context) {
+        self.video_slide_changed(ctx);
         let Some(doc) = &self.doc else { return };
         let mut to_play: Vec<crate::media::MediaClip> = vec![];
         let page = self.deck.slides.get(self.live()).map(|s| s.page);
@@ -1966,7 +1983,7 @@ impl App {
     pub fn script_report(&self) -> String {
         let ink: usize = self.side.ink.values().map(Vec::len).sum();
         format!(
-            "slide={} frame={} step={} tool={:?} screen={:?} frozen={:?} zoom={} ink={} laser={} timer={} audience={} swap={} history={} view={:?} questions={} slides={} tabs={:?} active={} bookmarks={:?} asked={:?} about={} update={:?} notice={:?} saved={:?} layout={:?} level={:.2} elapsed={:.1} target={} left={:?} missing={} warn={} status={:?} note={:?} cli={} copied={:?} syscheck={} packages={} recent={} toast={} skipped={:?} draft={:?} line={} log_open={} wrap={} follow={} anims={:?}",
+            "slide={} frame={} step={} tool={:?} screen={:?} frozen={:?} zoom={} ink={} laser={} timer={} audience={} swap={} history={} view={:?} questions={} slides={} tabs={:?} active={} bookmarks={:?} asked={:?} about={} update={:?} notice={:?} saved={:?} layout={:?} level={:.2} elapsed={:.1} target={} left={:?} missing={} warn={} status={:?} note={:?} cli={} copied={:?} syscheck={} packages={} recent={} toast={} skipped={:?} draft={:?} line={} log_open={} wrap={} follow={} anims={:?} videos={:?}",
             self.cur + 1,
             self.frame() + 1,
             self.deck.slides.get(self.cur).map(|s| s.step + 1).unwrap_or(0),
@@ -2017,6 +2034,14 @@ impl App {
                 v.sort();
                 v
             },
+            // Each clip's player: slide, file name, playing, seconds in, error.
+            self.players
+                .iter()
+                .map(|p| {
+                    let s = p.shared.lock().map(|s| (s.playing, (s.at * 10.0).round() / 10.0, s.error.clone())).unwrap_or_default();
+                    (p.frame_no, p.path.file_name().map(|n| n.to_string_lossy().to_string()).unwrap_or_default(), s.0, s.1, s.2)
+                })
+                .collect::<Vec<_>>(),
         )
     }
 
diff --git a/src/latex.rs b/src/latex.rs
index 041d870..af6ed97 100644
--- a/src/latex.rs
+++ b/src/latex.rs
@@ -187,12 +187,19 @@ pub fn compile(tex: &Path, engine: Engine) -> CompileResult {
     };
     let file = root.file_name().unwrap().to_owned();
     let stem = root.file_stem().unwrap().to_owned();
+    // Videos first: their posters must be there when LaTeX looks for them. TeXora's own packages
+    // (texoravideo) are found through TEXINPUTS; nothing is copied into the presentation's folder.
+    let videos = crate::video_prep::prepare(&root);
+    let texinputs = crate::video_prep::tex_dir().ok().map(|d| crate::video_prep::texinputs(&d));
     let mut pass = 0;
     let mut note = String::new();
     let (ok, log) = loop {
         pass += 1;
         let mut c = Command::new(&prog);
         c.current_dir(&dir).args(["-interaction=nonstopmode", "-file-line-error", "-synctex=1"]).arg(&file);
+        if let Some(t) = &texinputs {
+            c.env("TEXINPUTS", t);
+        }
         let run = run_with_timeout(c, Duration::from_secs(180));
         let log = String::from_utf8_lossy(&std::fs::read(&logf).unwrap_or_default()).to_string();
         let ran = match run {
@@ -231,8 +238,13 @@ pub fn compile(tex: &Path, engine: Engine) -> CompileResult {
         }
         break (true, log);
     };
-    let problems = parse_log(&log);
+    let mut problems = parse_log(&log);
     let has_error = problems.iter().any(|p| p.is_error);
+    // A clip that cannot be played does not stop the slides; it is listed, at its \includevideo.
+    for (f, line, message) in videos.problems {
+        let file = f.strip_prefix(&dir).map(|p| p.to_string_lossy().to_string()).unwrap_or_else(|_| f.to_string_lossy().to_string());
+        problems.push(Problem { file, line: Some(line), message, is_error: false });
+    }
     CompileResult { tab: 0, ok: ok && !has_error && pdf.exists(), pdf, problems, log, seconds: start.elapsed().as_secs_f32(), engine, note }
 }
 
@@ -444,6 +456,9 @@ pub fn requirements(src: &str, engine: Engine) -> Vec<Requirement> {
     for (f, _) in commands(&clean, "\\includegraphics") {
         add(ReqKind::File, f, exts(f, &["pdf", "png", "jpg", "jpeg", "eps"]), "Check the file name and folder.".to_string());
     }
+    for u in crate::video_prep::uses_in(&clean, std::path::Path::new("")) {
+        add(ReqKind::File, &u.path, vec![u.path.clone()], "Put the video in the .tex file's folder, or in a folder inside it written in the name ({videos/clip.mp4}).".to_string());
+    }
     for cmd in ["\\input", "\\include"] {
         for (f, _) in commands(&clean, cmd) {
             add(ReqKind::File, f, exts(f, &["tex"]), "Check the file name and folder.".to_string());
@@ -468,22 +483,38 @@ pub fn requirements(src: &str, engine: Engine) -> Vec<Requirement> {
     out
 }
 
-/// Looks each requirement up, using kpsewhich for TeX files and the folder for your own files.
+/// Looks each requirement up the way LaTeX does when TeXora compiles: the presentation's own folder
+/// first (a `.sty`, `.cls` or theme file beside the `.tex`), then TeXora's packages, then the TeX
+/// installation (kpsewhich, run from the presentation's folder with the same TEXINPUTS as a compile).
 pub fn check_requirements(src: &str, engine: Engine, dir: &Path) -> (Vec<Requirement>, Option<String>) {
     let mut reqs = requirements(src, engine);
     let kpse = find_tool("kpsewhich");
+    let texinputs = crate::video_prep::tex_dir().ok().map(|d| crate::video_prep::texinputs(&d));
+    let in_folder = |r: &Requirement| r.candidates.iter().any(|c| dir.join(c).is_file());
     for r in reqs.iter_mut() {
         r.found = match r.kind {
             ReqKind::Tool => find_tool(&r.candidates[0]).is_some(),
-            ReqKind::File => r.candidates.iter().any(|c| dir.join(c).is_file()),
+            ReqKind::File => in_folder(r),
+            // Built into TeXora: found through TEXINPUTS when TeXora compiles.
+            ReqKind::Package if r.name == "texoravideo" => true,
+            // A package, class, theme or TikZ library of your own, beside the presentation.
+            _ if in_folder(r) => true,
             _ => match &kpse {
                 Some(k) => {
-                    let out = Command::new(k).args(&r.candidates).output();
-                    out.map(|o| !String::from_utf8_lossy(&o.stdout).trim().is_empty()).unwrap_or(false)
+                    let mut c = Command::new(k);
+                    c.args(&r.candidates).current_dir(dir);
+                    if let Some(t) = &texinputs {
+                        c.env("TEXINPUTS", t);
+                    }
+                    c.output().map(|o| !String::from_utf8_lossy(&o.stdout).trim().is_empty()).unwrap_or(false)
                 }
                 None => false,
             },
         };
+        // Found means no install hint; one of your own files never needs tlmgr.
+        if r.found && !matches!(r.kind, ReqKind::Tool) {
+            r.hint.clear();
+        }
     }
     // A Unicode font package cannot work under pdfLaTeX, whatever is installed.
     let chosen = if engine == Engine::Auto { detect_engine(src) } else { engine };
@@ -583,6 +614,26 @@ mod tests {
         assert!(!found("nosuchpackagehere") && !found("NoSuchTheme") && !found("nosuchlib") && !found("nofile"));
     }
 
+    /// Issue #3: a package, class or theme file beside the presentation is found, with no tlmgr hint.
+    #[test]
+    fn files_beside_the_presentation_count_as_found() {
+        let dir = std::env::temp_dir().join(format!("texora-local-sty-{}", std::process::id()));
+        std::fs::create_dir_all(dir.join("styles")).unwrap();
+        for f in ["mytesting.sty", "myslides.cls", "beamerthemeCampus.sty", "styles/house.sty", "tikzlibrarymyshapes.code.tex"] {
+            std::fs::write(dir.join(f), "% local\n").unwrap();
+        }
+        let src = "\\documentclass{myslides}\n\\usepackage{mytesting}\n\\usepackage{styles/house}\n\\usetheme{Campus}\n\\usetikzlibrary{myshapes}\n\\usepackage{texoravideo}\n\\usepackage{nosuchpackagehere}\n";
+        let (r, _) = check_requirements(src, Engine::PdfLatex, &dir);
+        let get = |n: &str| r.iter().find(|x| x.name == n).unwrap().clone();
+        for n in ["myslides", "mytesting", "styles/house", "Campus", "myshapes", "texoravideo"] {
+            let x = get(n);
+            assert!(x.found, "{n} is beside the presentation (or built in)");
+            assert!(!x.hint.contains("tlmgr"), "no install hint for {n}: {}", x.hint);
+        }
+        let missing = get("nosuchpackagehere");
+        assert!(!missing.found && missing.hint.contains("tlmgr"), "a package found nowhere is still missing");
+    }
+
     #[test]
     fn fontspec_under_pdflatex_is_flagged() {
         let (_, warn) = check_requirements("\\usepackage{fontspec}", Engine::PdfLatex, &std::env::temp_dir());
diff --git a/src/main.rs b/src/main.rs
index be74bec..d408703 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -24,6 +24,9 @@ mod ui_present;
 mod ui_start;
 mod ui_studio;
 mod update;
+mod video;
+mod video_prep;
+mod ui_video;
 
 use app::{App, Args};
 use std::path::PathBuf;
diff --git a/src/pdf.rs b/src/pdf.rs
index d3f85aa..9464a32 100644
--- a/src/pdf.rs
+++ b/src/pdf.rs
@@ -62,6 +62,19 @@ pub struct PageInfo {
     /// Video and other clips on the page; `rect` is x0, y0, x1, y1 as fractions of the full page,
     /// from the top left, like links.
     pub media: Vec<PageMedia>,
+    pub videos: Vec<PageVideo>,
+}
+
+/// A clip placed with `\\includevideo` (the texoravideo package): a `texora-video:` link over its
+/// poster. `rect` is x0, y0, x1, y1 as fractions of the full page, from the top left, like links.
+#[derive(Clone, Debug, PartialEq)]
+pub struct PageVideo {
+    pub rect: [f32; 4],
+    pub link: crate::video_prep::LinkClip,
+    /// The file, when it may be played: inside the presentation's folder.
+    pub file: Option<PathBuf>,
+    /// Why it cannot be played, in words for the speaker.
+    pub problem: Option<String>,
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -246,6 +259,26 @@ pub fn spawn(wake: impl Fn() + Send + 'static) -> PdfEngine {
     PdfEngine { tx, rx }
 }
 
+/// A texoravideo clip of the PDF at `pdf`: its file beside the PDF, checked as when compiling, and the
+/// reason it cannot play (from the check, or as found when the posters were made, in index.json).
+fn video_on_page(pdf: &Path, rect: [f32; 4], link: crate::video_prep::LinkClip, index: &mut Option<crate::video_prep::Index>) -> PageVideo {
+    let dir = pdf.parent().unwrap_or(Path::new("."));
+    let index = index.get_or_insert_with(|| crate::video_prep::read_index(dir));
+    match crate::video_prep::locate(dir, &link.path) {
+        Ok((f, key)) => {
+            // What the compile found still holds while the clip is unchanged; otherwise look at it now.
+            // A clip the compile found unreadable stays so while it is unchanged. Otherwise it is looked at
+            // now, with the video tool installed now: a video waiting for ffmpeg or VLC plays as soon as
+            // one is there, without compiling again.
+            let known = index.posters.get(&crate::video_prep::poster_name(&key)).filter(|e| crate::video_prep::unchanged(e, &f));
+            let broken = known.and_then(|e| e.problem.clone()).filter(|p| p.starts_with("Not a video") || p.starts_with("Cannot play"));
+            let problem = broken.or_else(|| crate::video::check(&f).err().map(|p| p.message(&link.path)));
+            PageVideo { rect, problem, file: Some(f), link }
+        }
+        Err(p) => PageVideo { rect, problem: Some(p.message(&link.path)), file: None, link },
+    }
+}
+
 pub fn encode_png(w: u32, h: u32, rgba: &[u8]) -> Option<Vec<u8>> {
     use image::{codecs::png::PngEncoder, ExtendedColorType, ImageEncoder};
     let mut out = vec![];
@@ -262,6 +295,7 @@ fn inspect(doc: &PdfDocument, path: &Path) -> DocInfo {
         .filter(|s| !s.trim().is_empty())
         .unwrap_or_else(|| path.file_stem().map(|s| s.to_string_lossy().to_string()).unwrap_or_default());
     let mut media_at: Vec<(usize, [f32; 4], [f32; 4])> = vec![];
+    let mut index: Option<crate::video_prep::Index> = None;
     for page in doc.pages().iter() {
         let (w, h) = (page.width().value, page.height().value);
         let mut p = PageInfo { width: w, height: h, label: page.label().map(str::to_string), ..Default::default() };
@@ -288,6 +322,13 @@ fn inspect(doc: &PdfDocument, path: &Path) -> DocInfo {
                             .map(|i| LinkTarget::Page(i as usize))
                     })
                 });
+            // A texoravideo clip is played here, never opened as a web address.
+            if let Some(LinkTarget::Uri(u)) = &target {
+                if let Some(link) = crate::video_prep::parse_link(u) {
+                    p.videos.push(video_on_page(path, rect, link, &mut index));
+                    continue;
+                }
+            }
             if let Some(target) = target {
                 p.links.push(PageLink { rect, target });
             }
diff --git a/src/settings.rs b/src/settings.rs
index 08ed4b7..1f981d5 100644
--- a/src/settings.rs
+++ b/src/settings.rs
@@ -253,6 +253,12 @@ pub struct Settings {
     pub editor_size: f32,
     /// The LaTeX studio's editor wraps long lines at its width instead of scrolling sideways.
     pub editor_wrap: bool,
+    /// What plays videos that are not GIFs: "auto", "ffmpeg", "vlc" or "off". Only tools the person
+    /// installed are used; TeXora contains none.
+    pub video_player: String,
+    /// Where ffmpeg and VLC are, when not found by themselves; empty means "find it".
+    pub ffmpeg_path: String,
+    pub vlc_path: String,
     /// Look for a newer version when TeXora starts.
     pub check_updates: bool,
     /// A newer version the speaker chose to skip: its update notice is not shown again.
@@ -277,6 +283,9 @@ impl Default for Settings {
             notes_in_tex: true,
             editor_size: 14.0,
             editor_wrap: false,
+            video_player: "auto".to_string(),
+            ffmpeg_path: String::new(),
+            vlc_path: String::new(),
             check_updates: true,
             skipped_update: String::new(),
             last_template: String::new(),
diff --git a/src/templates.rs b/src/templates.rs
index a05c37a..614e707 100644
--- a/src/templates.rs
+++ b/src/templates.rs
@@ -1,7 +1,7 @@
 //! The Beamer templates offered for a new presentation. Each is a complete .tex file in
 //! assets/templates/, with two preview pictures made from it (its title slide and a content slide).
 //! To change one, edit its .tex file and run scripts/make-template-previews.sh.
-//! The animated templates also bring files of their own (pictures and a video clip), written into a
+//! The animated templates also bring files of their own (pictures and video clips), written into a
 //! `media` folder beside the new presentation.
 
 pub struct Template {
@@ -69,10 +69,16 @@ const FRAMES: &[(&str, &[u8])] = &[
     ("media/frame-30.png", include_bytes!("../assets/templates/media/frame-30.png")),
 ];
 
+/// The clips of the Video Guide template, played inside the slide by the texoravideo package.
+const VIDEOS: &[(&str, &[u8])] = &[
+    ("media/sample-video.mp4", include_bytes!("../assets/templates/video/sample-video.mp4")),
+    ("media/sample-loop.gif", include_bytes!("../assets/templates/video/sample-loop.gif")),
+];
+
 /// The video clip of the Media Studio template.
 const CLIP: &[(&str, &[u8])] = &[("media/clip.mp4", include_bytes!("../assets/templates/media/clip.mp4"))];
 
-pub const TEMPLATES: [Template; 8] = [
+pub const TEMPLATES: [Template; 9] = [
     template!("classic", "Classic Green", "Madrid theme with a calm green palette and a full information bar.", "16:9 · light · green"),
     template!("midnight", "Midnight", "Dark slides with amber highlights, easy on the eyes in a dim room.", "16:9 · dark · amber"),
     template!("minimal", "Minimal White", "Clean white slides, dark text and a single blue accent.", "16:9 · light · blue"),
@@ -81,6 +87,7 @@ pub const TEMPLATES: [Template; 8] = [
     template!("motion", "Motion Lab", "Dark slides with an orbit, a pendulum and a countdown drawn with TikZ: looping, back and forth, on a click and at changing speeds.", "16:9 · dark · animated"),
     template!("flipbook", "Flipbook", "Paper-white slides that play the frames of a GIF and bar charts that grow. The pictures come with it.", "4:3 · light · animated", FRAMES),
     template!("media", "Media Studio", "Violet slides with a video clip, a clip packed into the PDF, and charts that draw themselves. The clip comes with it.", "16:9 · light · video", CLIP),
+    template!("video", "Video Guide", "Navy and gold slides that show and explain videos and GIFs playing inside the slide, with \\includevideo. A video and a GIF come with it.", "16:9 · light · video", VIDEOS),
 ];
 
 /// Where the animated templates start in the list.
@@ -129,7 +136,7 @@ mod tests {
         }
         assert_eq!(themes.len(), TEMPLATES.len(), "every template looks different");
         for t in &TEMPLATES[FIRST_ANIMATED..] {
-            assert!(t.tex.contains("\\usepackage{animate}"), "{} is animated", t.id);
+            assert!(t.tex.contains("\\usepackage{animate}") || t.tex.contains("\\usepackage{texoravideo}"), "{} is animated", t.id);
             for (name, bytes) in t.files {
                 let stem = name.split('-').next().unwrap_or(name);
                 assert!(t.tex.contains(stem), "{} uses {name}", t.id);
diff --git a/src/ui_panels.rs b/src/ui_panels.rs
index b025019..6b8ab61 100644
--- a/src/ui_panels.rs
+++ b/src/ui_panels.rs
@@ -314,6 +314,7 @@ impl App {
             let force = std::mem::take(&mut self.show_packages).then_some(true);
             ui.add_space(4.0);
             CollapsingHeader::new(strong("Required LaTeX packages", 14.5)).id_salt(("settings", "Required LaTeX packages")).default_open(false).open(force).show(ui, |ui| self.required_packages(ui));
+            group(ui, "Video", false, &mut |ui| self.video_settings(ui));
             group(ui, "Speaker notes", false, &mut |ui| {
                 // A LaTeX presentation keeps its notes in the source, as \note{} in each slide.
                 let place = match (&self.src, self.st.notes_in_tex) {
diff --git a/src/ui_present.rs b/src/ui_present.rs
index a562bac..4bd6c7e 100644
--- a/src/ui_present.rs
+++ b/src/ui_present.rs
@@ -244,6 +244,7 @@ impl App {
         let uv = if idx == self.live() { uv_rect(self.zoom) } else { uv_rect(None) };
         self.paint_page(ui, rect, s.page, s.region, uv);
         self.paint_animations(ui, rect, s.page, s.region, uv);
+        self.paint_videos(ui, rect, idx, uv);
         if self.left == Some(LeftTab::Search) {
             // Search matches on this page. Page positions are of the whole page, so a slide
             // that fills only half of a double-width page needs converting.
@@ -396,12 +397,15 @@ impl App {
 
     /// Pointer behaviour over the live slide: drawing tools, laser, zoom, links and citation peeks.
     pub fn slide_input(&mut self, ui: &mut Ui, rect: Rect, idx: usize, id: &str) {
+        let uv = uv_rect(self.zoom);
+        let resp = ui.interact(rect, sid(id), Sense::click_and_drag());
+        // The animation buttons come after the slide's own area, so they sit on top of it and get
+        // their clicks; made first, the slide took every click and the buttons did nothing.
         if !id.starts_with("audience") {
             self.animation_controls(ui, rect, idx);
             self.media_badges(ui, rect, idx);
+            self.video_help(ui, rect, idx, uv);
         }
-        let uv = uv_rect(self.zoom);
-        let resp = ui.interact(rect, sid(id), Sense::click_and_drag());
         let pos = resp.hover_pos().or(resp.interact_pointer_pos());
         let Some(pos) = pos else { return };
         let p = to_slide(rect, uv, pos);
@@ -483,6 +487,24 @@ impl App {
                         self.zoom = None;
                     }
                 }
+                // A click on a texoravideo clip plays or pauses it, inside the slide.
+                if let Some(s) = self.deck.slides.get(idx).cloned() {
+                    let hit = self.video_rects(rect, s.page, s.region, uv).into_iter().find(|(_, r)| r.contains(pos)).map(|(v, _)| v);
+                    if let Some(v) = hit {
+                        ui.ctx().set_cursor_icon(CursorIcon::PointingHand);
+                        // A press and release in place on the clip is a click even when egui does not
+                        // report one, so play and pause never miss.
+                        let (down, up, at) = ui.input(|i| (i.pointer.primary_pressed(), i.pointer.primary_released(), i.pointer.interact_pos()));
+                        if down {
+                            self.video_press = at;
+                        }
+                        let own = up && self.video_press.take().zip(at).is_some_and(|(a, b)| a.distance(b) < 8.0);
+                        if resp.clicked() || own {
+                            self.video_click(ui.ctx(), idx, &v);
+                        }
+                        return;
+                    }
+                }
                 // A click on a video clip plays it in the computer's video player.
                 if let Some(s) = self.deck.slides.get(idx).cloned() {
                     let clip = self.media_rects(rect, s.page, s.region, uv).into_iter().find(|(_, r)| r.contains(pos)).map(|(c, _)| c);
@@ -1416,6 +1438,12 @@ impl App {
     // ---------- audience ----------
 
     pub fn audience_ui(&mut self, ui: &mut Ui) {
+        self.painting_audience = true;
+        self.audience_inner(ui);
+        self.painting_audience = false;
+    }
+
+    fn audience_inner(&mut self, ui: &mut Ui) {
         let full = ui.max_rect();
         ui.painter().rect_filled(full, 0.0, Color32::BLACK);
         let idx = self.live();
diff --git a/src/ui_video.rs b/src/ui_video.rs
new file mode 100644
index 0000000..ccd2e62
--- /dev/null
+++ b/src/ui_video.rs
@@ -0,0 +1,516 @@
+//! Playing texoravideo clips inside the slide.
+//!
+//! Each clip that plays has its own thread, which reads its frames (`video.rs`: a GIF decoded by TeXora,
+//! another video read from the person's own ffmpeg) and keeps time by the clock, handing the newest
+//! frame to the screen as an ordinary texture. A click plays or pauses, and showing another slide stops
+//! the player and its ffmpeg (overlay steps of the same slide keep it going). With VLC instead of
+//! ffmpeg, a click opens the clip in VLC's own window.
+use crate::video::{self, Frame};
+use egui::{Color32, Context, Rect, TextureHandle};
+use std::path::PathBuf;
+use std::sync::{mpsc, Arc, Mutex};
+use std::time::{Duration, Instant};
+
+enum Cmd {
+    Play,
+    Pause,
+    Stop,
+}
+
+/// What the player's thread shares with the screen.
+#[derive(Default)]
+pub struct Shared {
+    pub frame: Option<Frame>,
+    /// Goes up with every new frame, so the screen uploads each one once.
+    pub seq: u64,
+    pub playing: bool,
+    pub ended: bool,
+    pub error: Option<String>,
+    /// Seconds into the clip of the frame on show, and the clip's length.
+    pub at: f64,
+    pub duration: f64,
+}
+
+pub struct Player {
+    pub id: u64,
+    /// The slide (Beamer frame) it belongs to, and the document's generation.
+    pub frame_no: usize,
+    pub gen: u64,
+    pub path: PathBuf,
+    pub shared: Arc<Mutex<Shared>>,
+    tx: mpsc::Sender<Cmd>,
+    /// The texture the newest frame is in, and which frame that is.
+    rgba: Option<(u64, TextureHandle)>,
+}
+
+impl Player {
+    pub fn start(id: u64, frame_no: usize, gen: u64, path: PathBuf, name: String, repeat: bool, ctx: Context) -> Player {
+        let shared = Arc::new(Mutex::new(Shared::default()));
+        let (tx, rx) = mpsc::channel();
+        let (s, p) = (shared.clone(), path.clone());
+        std::thread::Builder::new()
+            .name("texora-video".into())
+            .spawn(move || run(&p, &name, repeat, &s, &rx, &ctx))
+            .ok();
+        Player { id, frame_no, gen, path, shared, tx, rgba: None }
+    }
+
+    pub fn playing(&self) -> bool {
+        self.shared.lock().map(|s| s.playing).unwrap_or(false)
+    }
+
+    pub fn play(&self) {
+        let _ = self.tx.send(Cmd::Play);
+    }
+
+    pub fn toggle(&self) {
+        let _ = self.tx.send(if self.playing() { Cmd::Pause } else { Cmd::Play });
+    }
+}
+
+impl Drop for Player {
+    /// The thread ends, and with it its ffmpeg process if the clip had one.
+    fn drop(&mut self) {
+        let _ = self.tx.send(Cmd::Stop);
+    }
+}
+
+/// The player's thread: waits while paused, and while playing shows each frame at its time.
+fn run(path: &std::path::Path, name: &str, repeat: bool, shared: &Mutex<Shared>, rx: &mpsc::Receiver<Cmd>, ctx: &Context) {
+    let set = |f: &dyn Fn(&mut Shared)| {
+        if let Ok(mut s) = shared.lock() {
+            f(&mut s);
+        }
+        ctx.request_repaint();
+    };
+    let mut stream = match video::open(path) {
+        Ok(s) => s,
+        Err(p) => {
+            let msg = p.message(name);
+            set(&|s| s.error = Some(msg.clone()));
+            return;
+        }
+    };
+    let duration = stream.info().duration;
+    set(&|s| s.duration = duration);
+    let (mut playing, mut ended) = (false, false);
+    let mut held: Option<Frame> = None;
+    let mut waiting: Option<Cmd> = None;
+    // The clip time `base` was on show at the instant `origin`.
+    let (mut origin, mut base, mut last) = (Instant::now(), 0.0f64, 0.0f64);
+    loop {
+        let cmd = match waiting.take() {
+            Some(c) => Some(c),
+            None if playing => rx.try_recv().ok(),
+            None => match rx.recv() {
+                Ok(c) => Some(c),
+                Err(_) => return,
+            },
+        };
+        match cmd {
+            Some(Cmd::Stop) => return,
+            Some(Cmd::Pause) => {
+                playing = false;
+                set(&|s| s.playing = false);
+                continue;
+            }
+            Some(Cmd::Play) => {
+                if ended {
+                    stream.seek(0.0);
+                    (held, last, ended) = (None, 0.0, false);
+                }
+                playing = true;
+                (origin, base) = (Instant::now(), last);
+                set(&|s| (s.playing, s.ended) = (true, false));
+            }
+            None => {}
+        }
+        if !playing {
+            continue;
+        }
+        let Some(f) = held.take().or_else(|| stream.next_frame()) else {
+            if repeat && last > 0.0 {
+                stream.seek(0.0);
+                (origin, base, last) = (Instant::now(), 0.0, 0.0);
+                continue;
+            }
+            (playing, ended) = (false, true);
+            set(&|s| (s.playing, s.ended) = (false, true));
+            continue;
+        };
+        let now = Instant::now();
+        let due = origin + Duration::from_secs_f64((f.at - base).max(0.0));
+        if due > now {
+            match rx.recv_timeout(due - now) {
+                Ok(c) => {
+                    // Answer at once; this frame waits for its turn.
+                    held = Some(f);
+                    waiting = Some(c);
+                    continue;
+                }
+                Err(mpsc::RecvTimeoutError::Disconnected) => return,
+                Err(mpsc::RecvTimeoutError::Timeout) => {}
+            }
+        } else if now - due > Duration::from_millis(400) {
+            // Far behind (the computer was busy): carry on from here rather than race.
+            (origin, base) = (now, f.at);
+        }
+        last = f.at;
+        if let Ok(mut s) = shared.lock() {
+            s.at = f.at;
+            s.frame = Some(f);
+            s.seq += 1;
+        }
+        ctx.request_repaint();
+    }
+}
+
+// ---------- drawing ----------
+
+/// Draws the player's newest frame in `rect`. Returns false while there is none yet (the poster in the
+/// PDF shows instead).
+pub fn paint(painter: &egui::Painter, ctx: &Context, player: &mut Player, rect: Rect) -> bool {
+    let fresh = {
+        let Ok(s) = player.shared.lock() else { return false };
+        let Some(f) = &s.frame else { return false };
+        let new = player.rgba.as_ref().is_none_or(|(q, _)| *q != s.seq);
+        new.then(|| (s.seq, egui::ColorImage::from_rgba_unmultiplied([f.picture.width as usize, f.picture.height as usize], &f.picture.data)))
+    };
+    if let Some((seq, img)) = fresh {
+        match &mut player.rgba {
+            Some((q, t)) => {
+                t.set(img, egui::TextureOptions::LINEAR);
+                *q = seq;
+            }
+            None => player.rgba = Some((seq, ctx.load_texture(format!("video-{}", player.id), img, egui::TextureOptions::LINEAR))),
+        }
+    }
+    if let Some((_, t)) = &player.rgba {
+        painter.image(t.id(), rect, Rect::from_min_max(egui::pos2(0.0, 0.0), egui::pos2(1.0, 1.0)), Color32::WHITE);
+    }
+    true
+}
+
+// ---------- help to install a video tool ----------
+
+/// Room at the bottom of a clip for the install buttons: two rows of small buttons.
+const HELP_H: f32 = 56.0;
+
+pub const VLC_PAGE: &str = "https://www.videolan.org";
+pub const FFMPEG_PAGE: &str = "https://ffmpeg.org/download.html";
+
+/// The command that installs ffmpeg on this system, for the person to run themselves. Windows has
+/// none: there the official download page is the way.
+pub fn install_command() -> Option<&'static str> {
+    if cfg!(target_os = "macos") {
+        Some("brew install ffmpeg")
+    } else if cfg!(target_os = "linux") {
+        Some(concat!("sudo", " apt install ffmpeg"))
+    } else {
+        None
+    }
+}
+
+/// "Get VLC", "Get ffmpeg" and "Copy install command". TeXora opens the pages and copies the command;
+/// it never downloads, installs or runs anything itself. Returns what to say after a copy.
+pub fn install_buttons(ui: &mut egui::Ui) -> Option<String> {
+    let mut said = None;
+    ui.vertical(|ui| {
+        ui.spacing_mut().item_spacing.y = 4.0;
+        ui.horizontal(|ui| {
+            if ui.small_button("Get VLC").on_hover_text(VLC_PAGE).clicked() {
+                ui.ctx().open_url(egui::OpenUrl::new_tab(VLC_PAGE));
+            }
+            if ui.small_button("Get ffmpeg").on_hover_text(FFMPEG_PAGE).clicked() {
+                ui.ctx().open_url(egui::OpenUrl::new_tab(FFMPEG_PAGE));
+            }
+        });
+        if let Some(cmd) = install_command() {
+            if ui.small_button("Copy install command").on_hover_text(cmd).clicked() {
+                ui.ctx().copy_text(cmd.to_string());
+                said = Some(format!("Copied \"{cmd}\". Paste it into Terminal and run it yourself; TeXora never runs it."));
+            }
+        }
+    });
+    said
+}
+
+// ---------- the app's side ----------
+
+use crate::app::App;
+use crate::pdf::{PageVideo, Region};
+use crate::ui_present::to_screen;
+
+/// Where a clip's rectangle is across the slide shown (one half of a double-width page, or all of it),
+/// if it lies inside that slide. A clip only counts when it is wholly inside: Beamer's notes pages
+/// carry a small copy of the slide whose links reach past the page's edge, and those are not clips.
+fn in_region(r: [f32; 4], region: Region) -> Option<(f32, f32)> {
+    let (x0, x1) = match region {
+        Region::Full => (r[0], r[2]),
+        Region::Left => (r[0] * 2.0, r[2] * 2.0),
+        Region::Right => (r[0] * 2.0 - 1.0, r[2] * 2.0 - 1.0),
+    };
+    let e = 0.01;
+    (x0 >= -e && x1 <= 1.0 + e && r[1] >= -e && r[3] <= 1.0 + e && x1 > x0).then_some((x0, x1))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn only_clips_inside_the_shown_slide_count() {
+        // The GIF of the Video Guide, and the copy of its link on the notes half, past the page's top.
+        let clip = [0.0278, 0.2837, 0.2633, 0.7581];
+        let notes_copy = [0.4028, -0.4663, 0.6383, 0.0081];
+        assert!(in_region(clip, Region::Left).is_some());
+        assert!(in_region(notes_copy, Region::Left).is_none());
+        assert!(in_region(notes_copy, Region::Right).is_none());
+        assert!(in_region([0.1, 0.2, 0.6, 0.8], Region::Full).is_some());
+        // A clip on the right half is not shown on the left.
+        assert!(in_region([0.6, 0.2, 0.9, 0.8], Region::Left).is_none());
+        assert!(in_region([0.6, 0.2, 0.9, 0.8], Region::Right).is_some());
+    }
+
+    #[test]
+    fn install_help_only_points_the_way() {
+        let cmd = install_command();
+        if cfg!(target_os = "macos") {
+            assert_eq!(cmd, Some("brew install ffmpeg"));
+        }
+        if cfg!(windows) {
+            assert_eq!(cmd, None, "Windows: the official download page only");
+        }
+        assert!(VLC_PAGE.starts_with("https://www.videolan.org") && FFMPEG_PAGE.starts_with("https://ffmpeg.org/"));
+    }
+}
+
+impl App {
+    /// Where each texoravideo clip of a page sits on screen, for a slide drawn in `rect`.
+    pub fn video_rects(&self, rect: Rect, page: usize, region: Region, uv: Rect) -> Vec<(PageVideo, Rect)> {
+        let Some(pg) = self.doc.as_ref().and_then(|d| d.pages.get(page)) else { return vec![] };
+        pg.videos
+            .iter()
+            .filter_map(|v| in_region(v.rect, region).map(|(x0, x1)| (v.clone(), Rect::from_two_pos(to_screen(rect, uv, [x0, v.rect[1]]), to_screen(rect, uv, [x1, v.rect[3]])))))
+            .collect()
+    }
+
+    fn player_index(&self, frame_no: usize, v: &PageVideo) -> Option<usize> {
+        let file = v.file.as_ref()?;
+        self.players.iter().position(|p| p.gen == self.gen && p.frame_no == frame_no && &p.path == file)
+    }
+
+    fn start_player(&mut self, ctx: &Context, frame_no: usize, v: &PageVideo) -> Option<usize> {
+        let file = v.file.clone()?;
+        self.player_seq += 1;
+        self.players.push(Player::start(self.player_seq, frame_no, self.gen, file, v.link.path.clone(), v.link.repeat, ctx.clone()));
+        Some(self.players.len() - 1)
+    }
+
+    /// A click on a clip: plays it, or pauses it while it plays. With VLC as the video tool, a clip that
+    /// is not a GIF opens in VLC's own window.
+    pub fn video_click(&mut self, ctx: &Context, idx: usize, v: &PageVideo) {
+        if let Some(p) = &v.problem {
+            self.status = p.replace('\n', " ");
+            return;
+        }
+        let Some(frame_no) = self.deck.slides.get(idx).map(|s| s.frame) else { return };
+        if let (Some(file), video::Backend::Vlc(vlc)) = (&v.file, video::backend()) {
+            if !video::is_gif_file(file) {
+                self.status = if self.is_screenshot() {
+                    format!("Would play {} in VLC.", v.link.path)
+                } else {
+                    match video::open_in_vlc(&vlc, file, v.link.repeat) {
+                        Ok(()) => format!("{} is playing in VLC.", v.link.path),
+                        Err(e) => format!("VLC could not be started: {e}"),
+                    }
+                };
+                return;
+            }
+        }
+        match self.player_index(frame_no, v) {
+            Some(i) => self.players[i].toggle(),
+            None => {
+                if let Some(i) = self.start_player(ctx, frame_no, v) {
+                    self.players[i].play();
+                }
+            }
+        }
+    }
+
+    /// Showing another slide stops its clips; the new slide's `autoplay` clips start. Overlay steps of
+    /// one slide count as the same slide, so a clip plays on through them.
+    pub fn video_slide_changed(&mut self, ctx: &Context) {
+        let Some(s) = self.deck.slides.get(self.live()).cloned() else {
+            self.players.clear();
+            self.video_frame = None;
+            return;
+        };
+        let now = Some((self.gen, s.frame));
+        if now == self.video_frame {
+            return;
+        }
+        self.video_frame = now;
+        let gen = self.gen;
+        self.players.retain(|p| p.gen == gen && p.frame_no == s.frame);
+        let videos = self.doc.as_ref().and_then(|d| d.pages.get(s.page)).map(|p| p.videos.clone()).unwrap_or_default();
+        // Clips start by themselves inside the slide only; VLC opens on a click.
+        let vlc = matches!(video::backend(), video::Backend::Vlc(_));
+        for v in videos.iter().filter(|v| v.link.autoplay && v.problem.is_none() && in_region(v.rect, s.region).is_some()) {
+            if vlc && !v.file.as_ref().is_some_and(|f| video::is_gif_file(f)) {
+                continue;
+            }
+            if self.player_index(s.frame, v).is_none() {
+                if let Some(i) = self.start_player(ctx, s.frame, v) {
+                    self.players[i].play();
+                }
+            }
+        }
+    }
+
+    /// Settings > Video: which installed tool plays videos that are not GIFs, where it is, and a test.
+    pub fn video_settings(&mut self, ui: &mut egui::Ui) {
+        use crate::app::{LEAF_DARK, MUTED};
+        use egui::RichText;
+        ui.label(RichText::new("GIFs play by themselves. MP4 and other videos play through VLC or ffmpeg installed on your computer: ffmpeg plays them inside the slide, VLC in its own window. TeXora contains no video decoder and never installs one.").size(12.5));
+        let mut changed = false;
+        ui.horizontal(|ui| {
+            ui.label("Video player");
+            let now = video::Choice::from_setting(&self.st.video_player);
+            egui::ComboBox::from_id_salt("video-player").selected_text(now.label()).show_ui(ui, |ui| {
+                for c in video::Choice::ALL {
+                    if ui.selectable_label(now == c, c.label()).clicked() {
+                        self.st.video_player = c.setting().to_string();
+                        changed = true;
+                    }
+                }
+            });
+        });
+        let found = video::tools();
+        let test_id = crate::ui_present::sid("video-tool-test");
+        for (name, vlc) in [("ffmpeg", false), ("VLC", true)] {
+            let text = if vlc { &mut self.st.vlc_path } else { &mut self.st.ffmpeg_path };
+            let auto = if vlc { &found.vlc } else { &found.ffmpeg };
+            let program = if text.trim().is_empty() { auto.clone() } else { Some(PathBuf::from(text.trim())).filter(|p| p.is_file()) };
+            ui.add_space(4.0);
+            ui.horizontal(|ui| {
+                ui.label(RichText::new(name).strong());
+                let state = match &program {
+                    Some(_) if text.trim().is_empty() => "found",
+                    Some(_) => "set by you",
+                    None => "not found",
+                };
+                ui.label(RichText::new(state).size(12.0).color(MUTED));
+                if ui.small_button("Test").clicked() {
+                    let said = match &program {
+                        Some(p) => match video::test_tool(p, vlc) {
+                            Ok(v) => format!("{name} works: {v}"),
+                            Err(e) => format!("{name} did not work: {e}"),
+                        },
+                        None => format!("{name} was not found on this computer."),
+                    };
+                    ui.ctx().data_mut(|d| d.insert_temp(test_id, said));
+                }
+            });
+            let hint = match auto {
+                Some(p) => p.display().to_string(),
+                None => "Path to the program (leave empty to look for it)".to_string(),
+            };
+            if ui.add(egui::TextEdit::singleline(text).hint_text(hint).desired_width(f32::INFINITY)).lost_focus() {
+                changed = true;
+            }
+        }
+        if let Some(said) = ui.ctx().data(|d| d.get_temp::<String>(test_id)) {
+            ui.label(RichText::new(said).size(12.5).color(LEAF_DARK));
+        }
+        let using = match video::backend() {
+            video::Backend::Ffmpeg(p) => format!("Videos play inside the slide through ffmpeg ({}).", p.display()),
+            video::Backend::Vlc(p) => format!("Videos open in VLC ({}). Install ffmpeg to play them inside the slide and to make their posters.", p.display()),
+            video::Backend::Off => "Video playing is off. GIFs still play.".to_string(),
+            video::Backend::None => video::NEEDS_PLAYER.to_string(),
+        };
+        ui.label(RichText::new(using).size(12.5).color(LEAF_DARK));
+        if matches!(video::backend(), video::Backend::None) || found.ffmpeg.is_none() {
+            if let Some(said) = install_buttons(ui) {
+                self.status = said;
+            }
+        }
+        if changed {
+            video::configure(&self.st.video_player, &self.st.ffmpeg_path, &self.st.vlc_path);
+            self.save_layout();
+        }
+    }
+
+    /// The install buttons over each clip of the slide that needs a video tool, on the speaker's screen.
+    /// They are made after the slide's own click area, so they get the clicks.
+    pub fn video_help(&mut self, ui: &mut egui::Ui, rect: Rect, idx: usize, uv: Rect) {
+        let Some(s) = self.deck.slides.get(idx).cloned() else { return };
+        for (i, (v, r)) in self.video_rects(rect, s.page, s.region, uv).into_iter().enumerate() {
+            if v.problem.as_deref() != Some(video::NEEDS_PLAYER) || r.height() <= 60.0 {
+                continue;
+            }
+            // Two rows, so the buttons wrap on a small clip instead of being cut off.
+            let area = Rect::from_min_max(egui::pos2(r.left() + 6.0, r.bottom() - HELP_H), egui::pos2(r.right() - 6.0, r.bottom() - 4.0)).intersect(rect);
+            let mut child = ui.new_child(egui::UiBuilder::new().max_rect(area).id_salt(("video-help", s.page, i)).layout(egui::Layout::top_down(egui::Align::Min)));
+            child.set_clip_rect(area);
+            if let Some(said) = install_buttons(&mut child) {
+                self.status = said;
+            }
+        }
+    }
+
+    /// The clips of a slide drawn in `rect`: their picture while they play, and for the speaker the
+    /// reason one cannot play, a play sign and how far it has got.
+    pub fn paint_videos(&mut self, ui: &egui::Ui, rect: Rect, idx: usize, uv: Rect) {
+        let Some(s) = self.deck.slides.get(idx).cloned() else { return };
+        let list = self.video_rects(rect, s.page, s.region, uv);
+        if list.is_empty() {
+            return;
+        }
+        let speaker = !self.painting_audience;
+        let painter = ui.painter().with_clip_rect(rect.intersect(ui.clip_rect()));
+        let ctx = ui.ctx().clone();
+        for (v, r) in list {
+            let mut state: Option<(bool, f64, f64, Option<String>)> = None;
+            if let Some(i) = self.player_index(s.frame, &v) {
+                paint(&painter, &ctx, &mut self.players[i], r);
+                state = self.players[i].shared.lock().ok().map(|x| (x.playing, x.at, x.duration, x.error.clone()));
+            }
+            if !speaker {
+                continue;
+            }
+            let problem = v.problem.clone().or_else(|| state.as_ref().and_then(|x| x.3.clone()));
+            if let Some(msg) = problem {
+                // Room below the words for the install buttons (see `video_help`).
+                let room = msg == video::NEEDS_PLAYER && r.height() > 60.0;
+                message(&painter, r, &msg, room);
+                continue;
+            }
+            let playing = state.as_ref().is_some_and(|x| x.0);
+            let hovered = ui.rect_contains_pointer(r);
+            if !playing && (hovered || state.is_some()) {
+                let d = (r.height().min(r.width()) * 0.3).clamp(22.0, 64.0);
+                painter.circle_filled(r.center(), d / 2.0, Color32::from_rgba_unmultiplied(20, 30, 25, 170));
+                crate::icons::paint(&painter, Rect::from_center_size(r.center() + egui::vec2(d * 0.05, 0.0), egui::vec2(d * 0.5, d * 0.5)), crate::icons::Icon::Play, Color32::WHITE);
+            }
+            if let Some((_, at, duration, _)) = state {
+                if duration > 0.0 {
+                    let bar = Rect::from_min_max(egui::pos2(r.left(), r.bottom() - 3.0), r.max);
+                    painter.rect_filled(bar, 0.0, Color32::from_rgba_unmultiplied(0, 0, 0, 90));
+                    let done = (at / duration).clamp(0.0, 1.0) as f32;
+                    painter.rect_filled(Rect::from_min_max(bar.min, egui::pos2(bar.left() + bar.width() * done, bar.bottom())), 0.0, crate::app::LEAF);
+                }
+            }
+        }
+    }
+}
+
+/// The reason a clip cannot play, written over its poster; `room_below` leaves space for buttons.
+fn message(painter: &egui::Painter, r: Rect, text: &str, room_below: bool) {
+    painter.rect_filled(r, 2.0, Color32::from_rgba_unmultiplied(25, 25, 28, 215));
+    let size = (r.height() / 11.0).clamp(10.0, 17.0);
+    let galley = painter.layout(text.to_string(), egui::FontId::proportional(size), Color32::WHITE, (r.width() - 16.0).max(40.0));
+    let centre = if room_below { egui::pos2(r.center().x, (r.top() + r.bottom() - HELP_H) / 2.0) } else { r.center() };
+    let at = centre - galley.size() / 2.0;
+    painter.galley(at, galley, Color32::WHITE);
+}
diff --git a/src/video.rs b/src/video.rs
new file mode 100644
index 0000000..d583d89
--- /dev/null
+++ b/src/video.rs
@@ -0,0 +1,833 @@
+//! Video and GIFs inside slides.
+//!
+//! TeXora contains no video decoder. GIFs are decoded by the `image` crate. Every other format (MP4,
+//! MOV, WebM...) is played through a video tool the person installed on their own computer:
+//! - **ffmpeg**: TeXora starts it as a separate program and reads plain RGBA pictures from it, so the
+//!   clip plays inside the slide; posters are made the same way.
+//! - **VLC**: the clip opens in VLC's own window.
+//!
+//! TeXora never downloads, installs, ships or updates ffmpeg or VLC. They are started with a list of
+//! arguments, never through a shell, and the file is passed as `file:<absolute path>` so its name can
+//! never be read as an option or as another kind of input.
+use std::fs::File;
+use std::io::{BufReader, Read};
+use std::path::{Path, PathBuf};
+use std::process::{Child, Command, Stdio};
+use std::sync::RwLock;
+use std::time::{Duration, Instant};
+
+/// Why a clip cannot be shown. The text is what TeXora writes over the poster.
+#[derive(Clone, Debug, PartialEq)]
+pub enum Problem {
+    /// No such file.
+    Missing,
+    /// The path leads outside the presentation's folder, or is a web address, or is not a file.
+    Refused(String),
+    /// A video file that could not be read, with the reason.
+    Broken(String),
+    /// Not a video or GIF at all.
+    NotVideo,
+    /// A video (not a GIF), and neither ffmpeg nor VLC was found.
+    NeedsPlayer,
+    /// Video playing is turned off in Settings.
+    PlayerOff,
+}
+
+/// The words over a clip that needs a video tool, also shown under Problems.
+pub const NEEDS_PLAYER: &str = "This video needs VLC or ffmpeg installed on your computer.";
+
+impl Problem {
+    pub fn message(&self, name: &str) -> String {
+        match self {
+            Problem::Missing => "Video not found: Place the video in the same folder as your .tex file or in a subfolder. If it's in a subfolder, include the folder path in \\includevideo.".to_string(),
+            Problem::Refused(why) => format!("Not played: {name}\n{why}"),
+            Problem::Broken(why) => format!("Cannot play {name}\n{why}"),
+            Problem::NotVideo => format!("Not a video: {name}\nUse a video file (such as MP4) or a GIF."),
+            Problem::NeedsPlayer => NEEDS_PLAYER.to_string(),
+            Problem::PlayerOff => format!("Not played: {name}\nVideo playing is turned off in Settings > Video."),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Kind {
+    Gif,
+    /// Played through ffmpeg.
+    External,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Info {
+    pub kind: Kind,
+    pub width: u32,
+    pub height: u32,
+    /// Seconds; 0 when unknown (a GIF before it has been played through).
+    pub duration: f64,
+}
+
+/// One picture, RGBA.
+#[derive(Clone, Debug)]
+pub struct Picture {
+    pub width: u32,
+    pub height: u32,
+    pub data: Vec<u8>,
+}
+
+/// A picture and when it is shown, in seconds from the start.
+#[derive(Clone, Debug)]
+pub struct Frame {
+    pub at: f64,
+    pub picture: Picture,
+}
+
+/// Frames of a clip, one after another. A stream is opened and read on one thread (the player's own).
+pub trait Stream {
+    fn info(&self) -> &Info;
+    /// The next frame, or None at the end.
+    fn next_frame(&mut self) -> Option<Frame>;
+    /// Starts again at `seconds` (a GIF goes back to its start and skips ahead).
+    fn seek(&mut self, seconds: f64);
+}
+
+// ---------- the video tools the person installed ----------
+
+/// Which video tool plays clips that are not GIFs (Settings > Video).
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
+pub enum Choice {
+    /// ffmpeg if found, else VLC.
+    #[default]
+    Auto,
+    Ffmpeg,
+    Vlc,
+    Off,
+}
+
+impl Choice {
+    pub const ALL: [Choice; 4] = [Choice::Auto, Choice::Ffmpeg, Choice::Vlc, Choice::Off];
+
+    pub fn from_setting(s: &str) -> Choice {
+        match s {
+            "ffmpeg" => Choice::Ffmpeg,
+            "vlc" => Choice::Vlc,
+            "off" => Choice::Off,
+            _ => Choice::Auto,
+        }
+    }
+
+    pub fn setting(self) -> &'static str {
+        match self {
+            Choice::Auto => "auto",
+            Choice::Ffmpeg => "ffmpeg",
+            Choice::Vlc => "vlc",
+            Choice::Off => "off",
+        }
+    }
+
+    pub fn label(self) -> &'static str {
+        match self {
+            Choice::Auto => "Auto",
+            Choice::Ffmpeg => "ffmpeg",
+            Choice::Vlc => "VLC",
+            Choice::Off => "Off",
+        }
+    }
+}
+
+/// What plays a clip that is not a GIF.
+#[derive(Clone, Debug, PartialEq)]
+pub enum Backend {
+    /// Inside the slide, through this ffmpeg.
+    Ffmpeg(PathBuf),
+    /// In VLC's own window.
+    Vlc(PathBuf),
+    /// Nothing found.
+    None,
+    Off,
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct Tools {
+    pub choice: Choice,
+    pub ffmpeg: Option<PathBuf>,
+    pub vlc: Option<PathBuf>,
+}
+
+static TOOLS: RwLock<Option<Tools>> = RwLock::new(None);
+
+/// Takes the Settings: the choice, and the paths typed in (empty means "find it").
+pub fn configure(choice: &str, ffmpeg_path: &str, vlc_path: &str) {
+    let pick = |typed: &str, find: fn() -> Option<PathBuf>| {
+        let t = typed.trim();
+        if t.is_empty() {
+            find()
+        } else {
+            Some(PathBuf::from(t)).filter(|p| p.is_file())
+        }
+    };
+    let t = Tools { choice: Choice::from_setting(choice), ffmpeg: pick(ffmpeg_path, find_ffmpeg), vlc: pick(vlc_path, find_vlc) };
+    if let Ok(mut g) = TOOLS.write() {
+        *g = Some(t);
+    }
+}
+
+pub fn tools() -> Tools {
+    if let Some(t) = TOOLS.read().ok().and_then(|g| g.clone()) {
+        return t;
+    }
+    configure("auto", "", "");
+    TOOLS.read().ok().and_then(|g| g.clone()).unwrap_or_default()
+}
+
+pub fn backend() -> Backend {
+    let t = tools();
+    match t.choice {
+        Choice::Off => Backend::Off,
+        Choice::Ffmpeg => t.ffmpeg.map(Backend::Ffmpeg).unwrap_or(Backend::None),
+        Choice::Vlc => t.vlc.map(Backend::Vlc).unwrap_or(Backend::None),
+        Choice::Auto => t.ffmpeg.map(Backend::Ffmpeg).or(t.vlc.map(Backend::Vlc)).unwrap_or(Backend::None),
+    }
+}
+
+/// The folders a program may be in, beyond PATH: where Homebrew, MacPorts, Linux packages and the
+/// usual Windows installers put it.
+fn search_dirs() -> Vec<PathBuf> {
+    let mut dirs: Vec<PathBuf> = std::env::var_os("PATH").map(|p| std::env::split_paths(&p).collect()).unwrap_or_default();
+    for d in ["/opt/homebrew/bin", "/usr/local/bin", "/opt/local/bin", "/usr/bin", "/snap/bin", "C:/ffmpeg/bin", "C:/Program Files/ffmpeg/bin", "C:/ProgramData/chocolatey/bin"] {
+        dirs.push(PathBuf::from(d));
+    }
+    if let Some(h) = dirs::home_dir() {
+        dirs.push(h.join("scoop/shims"));
+        dirs.push(h.join("AppData/Local/Microsoft/WinGet/Links"));
+        dirs.push(h.join(".local/bin"));
+    }
+    dirs
+}
+
+fn exe(name: &str) -> String {
+    if cfg!(windows) {
+        format!("{name}.exe")
+    } else {
+        name.to_string()
+    }
+}
+
+/// ffmpeg installed on this computer, if any.
+pub fn find_ffmpeg() -> Option<PathBuf> {
+    let name = exe("ffmpeg");
+    search_dirs().into_iter().map(|d| d.join(&name)).find(|p| p.is_file())
+}
+
+/// VLC installed on this computer, if any.
+pub fn find_vlc() -> Option<PathBuf> {
+    let mut places: Vec<PathBuf> = vec![];
+    if cfg!(target_os = "macos") {
+        places.push(PathBuf::from("/Applications/VLC.app/Contents/MacOS/VLC"));
+        if let Some(h) = dirs::home_dir() {
+            places.push(h.join("Applications/VLC.app/Contents/MacOS/VLC"));
+        }
+    }
+    if cfg!(windows) {
+        places.push(PathBuf::from("C:/Program Files/VideoLAN/VLC/vlc.exe"));
+        places.push(PathBuf::from("C:/Program Files (x86)/VideoLAN/VLC/vlc.exe"));
+    }
+    let name = exe("vlc");
+    places.extend(search_dirs().into_iter().map(|d| d.join(&name)));
+    places.into_iter().find(|p| p.is_file())
+}
+
+/// A command for a tool: no input, and no console window on Windows.
+fn tool_command(program: &Path) -> Command {
+    let mut c = Command::new(program);
+    c.stdin(Stdio::null());
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        c.creation_flags(0x0800_0000);
+    }
+    c
+}
+
+/// Runs a tool and returns what it wrote (output, errors), stopping it after `limit`.
+fn run_for(mut c: Command, limit: Duration) -> Result<(String, String), String> {
+    c.stdout(Stdio::piped()).stderr(Stdio::piped());
+    let mut child = c.spawn().map_err(|e| e.to_string())?;
+    let mut out = child.stdout.take();
+    let mut err = child.stderr.take();
+    let a = std::thread::spawn(move || {
+        let mut s = String::new();
+        if let Some(o) = out.as_mut() {
+            let _ = o.read_to_string(&mut s);
+        }
+        s
+    });
+    let b = std::thread::spawn(move || {
+        let mut s = String::new();
+        if let Some(e) = err.as_mut() {
+            let _ = e.read_to_string(&mut s);
+        }
+        s
+    });
+    let start = Instant::now();
+    loop {
+        match child.try_wait() {
+            Ok(Some(_)) => break,
+            Ok(None) if start.elapsed() > limit => {
+                let _ = child.kill();
+                let _ = child.wait();
+                return Err(format!("it did not answer within {} seconds", limit.as_secs()));
+            }
+            Ok(None) => std::thread::sleep(Duration::from_millis(20)),
+            Err(e) => return Err(e.to_string()),
+        }
+    }
+    Ok((a.join().unwrap_or_default(), b.join().unwrap_or_default()))
+}
+
+/// Settings > Video > Test: runs the tool with its version option and returns its first line.
+pub fn test_tool(program: &Path, vlc: bool) -> Result<String, String> {
+    if !program.is_file() {
+        return Err("No program at this path.".into());
+    }
+    let mut c = tool_command(program);
+    c.arg(if vlc { "--version" } else { "-version" });
+    let (out, err) = run_for(c, Duration::from_secs(8))?;
+    let text = if out.trim().is_empty() { err } else { out };
+    text.lines().map(str::trim).find(|l| !l.is_empty()).map(str::to_string).ok_or_else(|| "It started but did not say its version.".into())
+}
+
+/// A path as the tools read it: without the `\\?\` that Windows puts in front of canonical paths.
+fn plain(path: &Path) -> String {
+    let s = path.to_string_lossy().to_string();
+    if let Some(rest) = s.strip_prefix(r"\\?\UNC\") {
+        return format!(r"\\{rest}");
+    }
+    s.strip_prefix(r"\\?\").map(str::to_string).unwrap_or(s)
+}
+
+/// The input argument for ffmpeg: always the file protocol, so no name is read as another kind of input.
+fn ffmpeg_input(path: &Path) -> String {
+    format!("file:{}", plain(path))
+}
+
+/// The only kinds of file ffmpeg may read as a clip: real video containers. Playlists (HLS, concat,
+/// image sequences, SDP...) are left out, since a "video" that is really a playlist could make ffmpeg
+/// read other files or web addresses.
+pub const FFMPEG_FORMATS: &str = "mov,mp4,m4a,3gp,3g2,mj2,matroska,webm,avi,ogg,flv,mpeg,mpegts,asf";
+
+/// The options that open a clip in ffmpeg, safely, up to and including `-i <file>`:
+/// - `-nostdin`: never reads the keyboard;
+/// - `-protocol_whitelist file`: only local files, never web addresses or other protocols, also for
+///   anything the file itself points to;
+/// - `-format_whitelist`: only real video containers (see `FFMPEG_FORMATS`);
+/// - the file as `file:<absolute path>`, so no name is read as an option or another kind of input.
+///
+/// Only the path and the start time come from the presentation; the program is the person's own,
+/// from Settings, and no other argument can come from a project.
+pub fn ffmpeg_input_args(path: &Path, start: Option<f64>) -> Result<Vec<String>, Problem> {
+    if !path.is_absolute() {
+        return Err(Problem::Refused("TeXora only passes full paths to ffmpeg.".into()));
+    }
+    let mut a: Vec<String> = ["-hide_banner", "-nostdin", "-protocol_whitelist", "file", "-format_whitelist", FFMPEG_FORMATS].iter().map(|s| s.to_string()).collect();
+    if let Some(t) = start {
+        a.push("-ss".into());
+        a.push(format!("{:.3}", t.max(0.0)));
+    }
+    a.push("-i".into());
+    a.push(ffmpeg_input(path));
+    Ok(a)
+}
+
+/// The arguments that open a clip in VLC: its full path, after `--` so it is never read as an option.
+pub fn vlc_args(path: &Path, repeat: bool) -> Result<Vec<String>, String> {
+    if !path.is_absolute() {
+        return Err("TeXora only passes full paths to VLC.".into());
+    }
+    let mut a = vec!["--play-and-exit".to_string()];
+    if repeat {
+        a.push("--loop".into());
+    }
+    a.push("--".into());
+    a.push(plain(path));
+    Ok(a)
+}
+
+/// Opens a clip in VLC's own window. No shell is involved. Only a real video file is handed over (see
+/// `video_magic`): VLC would also play a playlist, which can point anywhere.
+pub fn open_in_vlc(vlc: &Path, path: &Path, repeat: bool) -> Result<(), String> {
+    if !head(path).is_ok_and(|h| video_magic(&h)) {
+        return Err("it is not a video file VLC may open.".into());
+    }
+    let mut c = tool_command(vlc);
+    c.args(vlc_args(path, repeat)?).stdout(Stdio::null()).stderr(Stdio::null());
+    c.spawn().map(|_| ()).map_err(|e| e.to_string())
+}
+
+// ---------- what a file is ----------
+
+/// Whether a file's first bytes are those of a real video container (MP4/MOV, Matroska/WebM, AVI, Ogg,
+/// FLV, MPEG). Its name does not count: a playlist renamed `.mp4` is text, and fails this.
+fn video_magic(head: &[u8]) -> bool {
+    (head.len() >= 8 && &head[4..8] == b"ftyp")
+        || head.starts_with(&[0x1A, 0x45, 0xDF, 0xA3])
+        || (head.starts_with(b"RIFF") && head.len() >= 12 && &head[8..12] == b"AVI ")
+        || head.starts_with(b"OggS")
+        || head.starts_with(b"FLV")
+        || head.starts_with(&[0x00, 0x00, 0x01, 0xBA])
+        || head.starts_with(&[0x00, 0x00, 0x01, 0xB3])
+        || (head.first() == Some(&0x47) && head.len() >= 2 && head[1] & 0x80 == 0)
+}
+
+/// Whether a file looks like a video, from its first bytes or else its name, to say what is needed
+/// when no video tool is there to ask.
+fn looks_like_video(path: &Path, head: &[u8]) -> bool {
+    let ext = path.extension().map(|e| e.to_string_lossy().to_lowercase()).unwrap_or_default();
+    video_magic(head) || ["mp4", "m4v", "mov", "mkv", "webm", "avi", "ogv", "flv", "mpg", "mpeg", "ts", "wmv", "3gp"].contains(&ext.as_str())
+}
+
+fn head(path: &Path) -> Result<Vec<u8>, Problem> {
+    let mut f = File::open(path).map_err(|e| if e.kind() == std::io::ErrorKind::NotFound { Problem::Missing } else { Problem::Broken(e.to_string()) })?;
+    let mut h = [0u8; 16];
+    let n = f.read(&mut h).map_err(|e| Problem::Broken(e.to_string()))?;
+    Ok(h[..n].to_vec())
+}
+
+fn is_gif(h: &[u8]) -> bool {
+    h.starts_with(b"GIF87a") || h.starts_with(b"GIF89a")
+}
+
+/// Whether this clip is a GIF (played by TeXora itself).
+pub fn is_gif_file(path: &Path) -> bool {
+    head(path).map(|h| is_gif(&h)).unwrap_or(false)
+}
+
+/// Whether a clip can be shown, without playing it: a GIF always; another video when a video tool is
+/// there (ffmpeg is asked whether it can read it).
+pub fn check(path: &Path) -> Result<(), Problem> {
+    if !path.exists() {
+        return Err(Problem::Missing);
+    }
+    if !path.is_file() {
+        return Err(Problem::Refused("It is a folder, not a file.".into()));
+    }
+    let h = head(path)?;
+    if is_gif(&h) {
+        return Ok(());
+    }
+    match backend() {
+        Backend::Ffmpeg(ff) => probe(&ff, path).map(|_| ()),
+        // VLC gets only a real video file, never a playlist (see `open_in_vlc`).
+        Backend::Vlc(_) if !video_magic(&h) => Err(Problem::NotVideo),
+        Backend::Vlc(_) => Ok(()),
+        _ if !looks_like_video(path, &h) => Err(Problem::NotVideo),
+        Backend::Off => Err(Problem::PlayerOff),
+        Backend::None => Err(Problem::NeedsPlayer),
+    }
+}
+
+/// Opens a clip for playing inside the slide: a GIF by TeXora, another video through ffmpeg.
+pub fn open(path: &Path) -> Result<Box<dyn Stream>, Problem> {
+    if !path.exists() {
+        return Err(Problem::Missing);
+    }
+    if !path.is_file() {
+        return Err(Problem::Refused("It is a folder, not a file.".into()));
+    }
+    let h = head(path)?;
+    if is_gif(&h) {
+        return Ok(Box::new(GifStream::open(path)?));
+    }
+    match backend() {
+        Backend::Ffmpeg(ff) => Ok(Box::new(FfmpegStream::open(&ff, path, 0.0)?)),
+        _ if !looks_like_video(path, &h) => Err(Problem::NotVideo),
+        Backend::Off => Err(Problem::PlayerOff),
+        // VLC plays in its own window (`open_in_vlc`); playing inside the slide needs ffmpeg.
+        Backend::Vlc(_) | Backend::None => Err(Problem::NeedsPlayer),
+    }
+}
+
+// ---------- ffmpeg ----------
+
+/// What ffmpeg says about a file's video: its size (upright), frames per second and length.
+#[derive(Clone, Debug, PartialEq)]
+pub struct Probe {
+    pub width: u32,
+    pub height: u32,
+    pub fps: f64,
+    pub duration: f64,
+}
+
+/// Reads what `ffmpeg -i <file>` writes about a file. None when it has no video stream.
+pub fn parse_probe(text: &str) -> Option<Probe> {
+    let duration = text.lines().find_map(|l| {
+        let rest = l.trim().strip_prefix("Duration:")?;
+        let t = rest.trim().split(',').next()?.trim();
+        let p: Vec<f64> = t.split(':').filter_map(|x| x.parse().ok()).collect();
+        (p.len() == 3).then(|| p[0] * 3600.0 + p[1] * 60.0 + p[2])
+    });
+    let line = text.lines().find(|l| l.contains("Stream #") && l.contains("Video:"))?;
+    let size = line
+        .split(|c: char| c == ' ' || c == ',' || c == '[' || c == ']' || c == '(' || c == ')')
+        .filter(|t| !t.starts_with("0x"))
+        .find_map(|t| {
+            let (a, b) = t.split_once('x')?;
+            let (w, h) = (a.parse::<u32>().ok()?, b.parse::<u32>().ok()?);
+            (w > 0 && h > 0).then_some((w, h))
+        })?;
+    let rate = |unit: &str| {
+        line.split(',').find_map(|part| {
+            let v = part.trim().strip_suffix(unit)?.trim();
+            let (num, k) = match v.strip_suffix('k') {
+                Some(n) => (n, 1000.0),
+                None => (v, 1.0),
+            };
+            num.parse::<f64>().ok().map(|f| f * k).filter(|f| *f > 0.0 && *f < 1000.0)
+        })
+    };
+    let fps = rate("fps").or_else(|| rate("tbr")).unwrap_or(25.0).clamp(1.0, 60.0);
+    // ffmpeg turns a phone video upright as it decodes it, so its size is then the other way round.
+    let turned = text.lines().any(|l| l.contains("rotation of") && (l.contains("90.00") || l.contains("270.00")));
+    let (width, height) = if turned { (size.1, size.0) } else { size };
+    Some(Probe { width, height, fps, duration: duration.unwrap_or(0.0) })
+}
+
+/// Asks ffmpeg what a file holds.
+pub fn probe(ffmpeg: &Path, path: &Path) -> Result<Probe, Problem> {
+    let mut c = tool_command(ffmpeg);
+    c.args(ffmpeg_input_args(path, None)?);
+    let (_, err) = run_for(c, Duration::from_secs(15)).map_err(|e| Problem::Broken(format!("ffmpeg could not be run: {e}.")))?;
+    parse_probe(&err).ok_or(Problem::NotVideo)
+}
+
+/// The size pictures are read at: the video's own, made smaller to fit 1280 x 720 (in even numbers,
+/// as ffmpeg needs).
+pub fn read_size(w: u32, h: u32) -> (u32, u32) {
+    let scale = (1280.0 / w as f64).min(720.0 / h as f64).min(1.0);
+    let even = |v: f64| ((v / 2.0).round() as u32 * 2).max(2);
+    (even(w as f64 * scale), even(h as f64 * scale))
+}
+
+/// A video played by ffmpeg, which runs as a separate program and writes RGBA pictures to TeXora.
+pub struct FfmpegStream {
+    info: Info,
+    ffmpeg: PathBuf,
+    path: PathBuf,
+    fps: f64,
+    size: (u32, u32),
+    child: Option<Child>,
+    start: f64,
+    n: u64,
+}
+
+impl FfmpegStream {
+    pub fn open(ffmpeg: &Path, path: &Path, from: f64) -> Result<FfmpegStream, Problem> {
+        let p = probe(ffmpeg, path)?;
+        let size = read_size(p.width, p.height);
+        let info = Info { kind: Kind::External, width: size.0, height: size.1, duration: p.duration };
+        let mut s = FfmpegStream { info, ffmpeg: ffmpeg.to_path_buf(), path: path.to_path_buf(), fps: p.fps, size, child: None, start: 0.0, n: 0 };
+        s.start_at(from)?;
+        Ok(s)
+    }
+
+    fn start_at(&mut self, seconds: f64) -> Result<(), Problem> {
+        self.end_process();
+        let mut c = tool_command(&self.ffmpeg);
+        c.args(["-loglevel", "error"]).args(ffmpeg_input_args(&self.path, Some(seconds))?);
+        c.args(["-an", "-sn", "-dn", "-vf"]).arg(format!("scale={}:{}:flags=bilinear", self.size.0, self.size.1));
+        c.arg("-r").arg(format!("{:.3}", self.fps));
+        c.args(["-pix_fmt", "rgba", "-f", "rawvideo", "pipe:1"]);
+        c.stdout(Stdio::piped()).stderr(Stdio::null());
+        let child = c.spawn().map_err(|e| Problem::Broken(format!("ffmpeg could not be started: {e}.")))?;
+        (self.child, self.start, self.n) = (Some(child), seconds.max(0.0), 0);
+        Ok(())
+    }
+
+    /// Ends the ffmpeg process, if one is running.
+    fn end_process(&mut self) {
+        if let Some(mut c) = self.child.take() {
+            let _ = c.kill();
+            let _ = c.wait();
+        }
+    }
+}
+
+impl Drop for FfmpegStream {
+    /// The ffmpeg process goes with the stream, so another slide ends it.
+    fn drop(&mut self) {
+        self.end_process();
+    }
+}
+
+impl Stream for FfmpegStream {
+    fn info(&self) -> &Info {
+        &self.info
+    }
+
+    fn next_frame(&mut self) -> Option<Frame> {
+        let (w, h) = self.size;
+        let out = self.child.as_mut()?.stdout.as_mut()?;
+        let mut data = vec![0u8; (w * h * 4) as usize];
+        if out.read_exact(&mut data).is_err() {
+            self.end_process();
+            return None;
+        }
+        let at = self.start + self.n as f64 / self.fps;
+        self.n += 1;
+        Some(Frame { at, picture: Picture { width: w, height: h, data } })
+    }
+
+    fn seek(&mut self, seconds: f64) {
+        let _ = self.start_at(seconds);
+    }
+}
+
+// ---------- GIF ----------
+
+pub struct GifStream {
+    info: Info,
+    path: PathBuf,
+    frames: Option<image::Frames<'static>>,
+    at: f64,
+    /// A frame read ahead while seeking, handed out next.
+    pending: Option<Frame>,
+}
+
+impl GifStream {
+    pub fn open(path: &Path) -> Result<GifStream, Problem> {
+        let mut s = GifStream { info: Info { kind: Kind::Gif, width: 0, height: 0, duration: 0.0 }, path: path.to_path_buf(), frames: None, at: 0.0, pending: None };
+        s.restart()?;
+        Ok(s)
+    }
+
+    fn restart(&mut self) -> Result<(), Problem> {
+        use image::AnimationDecoder;
+        use image::ImageDecoder;
+        let f = File::open(&self.path).map_err(|e| Problem::Broken(e.to_string()))?;
+        let d = image::codecs::gif::GifDecoder::new(BufReader::new(f)).map_err(|e| Problem::Broken(format!("The GIF could not be read ({e}).")))?;
+        let (w, h) = d.dimensions();
+        (self.info.width, self.info.height) = (w, h);
+        self.frames = Some(d.into_frames());
+        self.at = 0.0;
+        self.pending = None;
+        Ok(())
+    }
+}
+
+impl Stream for GifStream {
+    fn info(&self) -> &Info {
+        &self.info
+    }
+
+    fn next_frame(&mut self) -> Option<Frame> {
+        if let Some(f) = self.pending.take() {
+            return Some(f);
+        }
+        let f = self.frames.as_mut()?.next()?.ok()?;
+        let (num, den) = f.delay().numer_denom_ms();
+        // Browsers show a GIF frame with no delay for a tenth of a second; so does TeXora.
+        let ms = if den == 0 { 100.0 } else { num as f64 / den as f64 };
+        let ms = if ms < 20.0 { 100.0 } else { ms };
+        let buf = f.into_buffer();
+        let frame = Frame { at: self.at, picture: Picture { width: buf.width(), height: buf.height(), data: buf.into_raw() } };
+        self.at += ms / 1000.0;
+        self.info.duration = self.info.duration.max(self.at);
+        Some(frame)
+    }
+
+    fn seek(&mut self, seconds: f64) {
+        let _ = self.restart();
+        // Frames before the time are decoded and dropped; a GIF has no key frames to jump to.
+        if seconds > 0.0 {
+            while let Some(f) = self.next_frame() {
+                if self.at > seconds {
+                    self.pending = Some(f);
+                    break;
+                }
+            }
+        }
+    }
+}
+
+// ---------- posters ----------
+
+/// The picture `fraction` of the way into the clip (0 is the first frame), as RGBA. A GIF's poster is
+/// made by TeXora; another video's needs ffmpeg.
+pub fn poster(path: &Path, fraction: f64) -> Result<(u32, u32, Vec<u8>), Problem> {
+    let h = head(path)?;
+    let f = fraction.clamp(0.0, 0.99);
+    let frame = if is_gif(&h) {
+        let mut s = GifStream::open(path)?;
+        if f > 0.0 {
+            // A GIF's length is known only once read through.
+            while s.next_frame().is_some() {}
+            let target = s.info().duration * f;
+            s.seek(target);
+        }
+        s.next_frame()
+    } else {
+        let ff = match (backend(), tools().ffmpeg) {
+            (Backend::Ffmpeg(ff), _) => ff,
+            // VLC plays the clip, but only ffmpeg can make its poster.
+            (Backend::Vlc(_), Some(ff)) => ff,
+            _ if !looks_like_video(path, &h) => return Err(Problem::NotVideo),
+            (Backend::Off, _) => return Err(Problem::PlayerOff),
+            _ => return Err(Problem::NeedsPlayer),
+        };
+        let p = probe(&ff, path)?;
+        FfmpegStream::open(&ff, path, p.duration * f)?.next_frame()
+    };
+    let f = frame.ok_or_else(|| Problem::Broken("No picture could be read from it.".into()))?;
+    Ok((f.picture.width, f.picture.height, f.picture.data))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn clip(name: &str) -> PathBuf {
+        Path::new(env!("CARGO_MANIFEST_DIR")).join("assets/test/video").join(name)
+    }
+
+    #[test]
+    fn gif_is_built_in() {
+        let mut g = open(&clip("test.gif")).unwrap();
+        let f = g.next_frame().unwrap();
+        assert_eq!((f.picture.width, f.picture.height), (320, 180));
+        let mut n = 1;
+        while g.next_frame().is_some() {
+            n += 1;
+        }
+        assert_eq!(n, 20);
+        assert!((g.info().duration - 2.0).abs() < 0.05);
+        let (gw, _, _) = poster(&clip("test.gif"), 0.25).unwrap();
+        assert_eq!(gw, 320);
+    }
+
+    #[test]
+    fn ffmpeg_output_is_read() {
+        let text = "Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file:/x/test.mp4':\n  Duration: 00:00:04.00, start: 0.000000, bitrate: 941 kb/s\n  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 640x360 [SAR 1:1 DAR 16:9], 937 kb/s, 30 fps, 30 tbr, 15360 tbn (default)\n";
+        assert_eq!(parse_probe(text), Some(Probe { width: 640, height: 360, fps: 30.0, duration: 4.0 }));
+        let phone = "  Duration: 00:01:02.50, start: 0.000000\n  Stream #0:0: Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bt709), 1920x1080, 29.97 fps, 29.97 tbr\n      displaymatrix: rotation of -90.00 degrees\n";
+        let p = parse_probe(phone).unwrap();
+        assert_eq!((p.width, p.height, p.duration), (1080, 1920, 62.5));
+        assert!((p.fps - 29.97).abs() < 1e-9);
+        assert_eq!(parse_probe("Input #0, mp3\n  Stream #0:0: Audio: mp3, 44100 Hz\n"), None);
+        assert_eq!(read_size(1920, 1080), (1280, 720));
+        assert_eq!(read_size(640, 360), (640, 360));
+        assert_eq!(read_size(1080, 1920), (406, 720));
+    }
+
+    #[test]
+    fn ffmpeg_and_vlc_arguments_are_safe() {
+        // ffmpeg: no shell, no keyboard, local files only, real video containers only, and the file
+        // as `file:<full path>` right after -i, even when its name starts with "-".
+        // A full path on this system (on Windows it starts with a drive, such as C:\).
+        let talk = std::env::temp_dir().join("talk");
+        let odd = talk.join("-y -i x.mp4");
+        let a = ffmpeg_input_args(&odd, Some(2.0)).unwrap();
+        let at = |s: &str| a.iter().position(|x| x == s).unwrap();
+        assert!(at("-nostdin") < at("-i") && at("-protocol_whitelist") < at("-i") && at("-format_whitelist") < at("-i"));
+        assert_eq!(a[at("-protocol_whitelist") + 1], "file");
+        assert!(!FFMPEG_FORMATS.split(',').any(|f| ["concat", "hls", "applehttp", "image2", "sdp", "rtp", "rtsp", "tee", "data", "lavfi"].contains(&f)), "no playlist formats");
+        assert_eq!(a.last().unwrap(), &format!("file:{}", plain(&odd)));
+        assert!(a.last().unwrap().ends_with("-y -i x.mp4"), "the name stays one argument");
+        assert_eq!(a[a.len() - 2], "-i");
+        assert!(ffmpeg_input_args(Path::new("clip.mp4"), None).is_err(), "only full paths");
+        // VLC: the full path after "--", so a name starting with "-" is never an option.
+        let named = talk.join("--extraintf=http.mp4");
+        let v = vlc_args(&named, true).unwrap();
+        assert_eq!(v, vec!["--play-and-exit".to_string(), "--loop".to_string(), "--".to_string(), plain(&named)]);
+        assert!(!v[3].starts_with('-'), "a full path never starts with '-'");
+        assert!(vlc_args(Path::new("--extraintf=http.mp4"), false).is_err(), "only full paths");
+    }
+
+    #[test]
+    fn a_playlist_named_like_a_video_is_not_a_video() {
+        let dir = std::env::temp_dir().join(format!("texora-playlist-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        let hls = dir.join("clip.mp4");
+        std::fs::write(&hls, "#EXTM3U\n#EXT-X-TARGETDURATION:4\n#EXTINF:4,\nhttp://example.com/x.ts\n#EXT-X-ENDLIST\n").unwrap();
+        assert!(!video_magic(&head(&hls).unwrap()), "VLC never gets a playlist");
+        assert!(video_magic(&head(&clip("test.mp4")).unwrap()));
+        assert!(video_magic(&head(&clip("hevc.mp4")).unwrap()));
+        assert!(!video_magic(&head(&clip("test.txt")).unwrap()));
+        assert!(open_in_vlc(Path::new("/nonexistent/vlc"), &hls, false).unwrap_err().contains("not a video"));
+    }
+
+    /// With the real ffmpeg: files that are really a concat list or an HLS playlist, named `.mp4`, are
+    /// refused. Without the whitelists, ffmpeg would follow them to another file.
+    #[test]
+    fn ffmpeg_never_follows_a_playlist_inside_a_file() {
+        let Some(ff) = find_ffmpeg() else { return };
+        let dir = std::env::temp_dir().join(format!("texora-crafted-{}", std::process::id())).canonicalize().unwrap_or_else(|_| {
+            let d = std::env::temp_dir().join(format!("texora-crafted-{}", std::process::id()));
+            std::fs::create_dir_all(&d).unwrap();
+            d.canonicalize().unwrap()
+        });
+        std::fs::create_dir_all(&dir).unwrap();
+        // The "other file" a crafted clip tries to reach: a real video beside it.
+        let secret = dir.join("private.mp4");
+        std::fs::copy(clip("test.mp4"), &secret).unwrap();
+        // A concat list named like a video, and a playlist that points to the web.
+        let concat = dir.join("near.mp4");
+        std::fs::write(&concat, "ffconcat version 1.0\nfile 'private.mp4'\n").unwrap();
+        let web = dir.join("web.m3u8");
+        std::fs::write(&web, "#EXTM3U\n#EXT-X-TARGETDURATION:4\n#EXTINF:4,\nhttp://127.0.0.1:9/x.ts\n#EXT-X-ENDLIST\n").unwrap();
+        // Plain ffmpeg (as of version 9) does follow both: the danger is real.
+        let plain = |f: &Path| {
+            let mut c = tool_command(&ff);
+            c.args(["-hide_banner", "-nostdin", "-i"]).arg(ffmpeg_input(f));
+            run_for(c, Duration::from_secs(15)).map(|(_, e)| e).unwrap_or_default()
+        };
+        let (near, far) = (plain(&concat), plain(&web));
+        assert!(near.contains("Video:") || near.contains("Unsafe"), "plain ffmpeg reads the list: {near}");
+        assert!(far.contains("http://") || far.contains("Invalid data"), "plain ffmpeg goes to the web: {far}");
+        // TeXora's way refuses both, and the same for its posters and playing.
+        for f in [&concat, &web] {
+            assert_eq!(probe(&ff, f).err(), Some(Problem::NotVideo), "{}", f.display());
+            assert!(FfmpegStream::open(&ff, f, 0.0).is_err());
+        }
+        // A real clip still plays.
+        assert!(probe(&ff, &secret).is_ok());
+    }
+
+    #[test]
+    fn tool_arguments_are_safe() {
+        assert_eq!(ffmpeg_input(Path::new("/a b/-i x.mp4")), "file:/a b/-i x.mp4");
+        assert_eq!(plain(Path::new(r"\\?\C:\talk\clip.mp4")), r"C:\talk\clip.mp4");
+        assert_eq!(plain(Path::new(r"\\?\UNC\server\share\clip.mp4")), r"\\server\share\clip.mp4");
+        assert_eq!(Choice::from_setting("vlc").setting(), "vlc");
+        assert_eq!(Choice::from_setting("anything"), Choice::Auto);
+    }
+
+    #[test]
+    fn files_are_told_apart_without_a_tool() {
+        let h = head(&clip("test.mp4")).unwrap();
+        assert!(looks_like_video(&clip("test.mp4"), &h));
+        let t = head(&clip("test.txt")).unwrap();
+        assert!(!looks_like_video(&clip("test.txt"), &t));
+        assert_eq!(check(&clip("does-not-exist.mp4")), Err(Problem::Missing));
+        assert!(is_gif_file(&clip("test.gif")) && !is_gif_file(&clip("test.mp4")));
+    }
+
+    /// Runs only where ffmpeg is installed, as on the computer that builds TeXora.
+    #[test]
+    fn videos_play_through_installed_ffmpeg() {
+        let Some(ff) = find_ffmpeg() else { return };
+        let mut s = FfmpegStream::open(&ff, &clip("test.mp4"), 0.0).expect("opens");
+        assert_eq!((s.info().width, s.info().height), (640, 360));
+        assert!((s.info().duration - 4.0).abs() < 0.1);
+        let (mut n, mut last) = (0, -1.0);
+        while let Some(f) = s.next_frame() {
+            assert!(f.at > last);
+            last = f.at;
+            n += 1;
+        }
+        assert_eq!(n, 120, "4 s at 30 frames per second");
+        s.seek(2.0);
+        assert!((s.next_frame().unwrap().at - 2.0).abs() < 0.01);
+        // Other formats play too, through the person's ffmpeg.
+        assert_eq!(FfmpegStream::open(&ff, &clip("hevc.mp4"), 0.0).unwrap().info().width, 320);
+        assert_eq!(probe(&ff, &clip("test.txt")).err(), Some(Problem::NotVideo));
+        assert!(test_tool(&ff, false).unwrap().starts_with("ffmpeg version"));
+    }
+}
diff --git a/src/video_prep.rs b/src/video_prep.rs
new file mode 100644
index 0000000..9d3d154
--- /dev/null
+++ b/src/video_prep.rs
@@ -0,0 +1,659 @@
+//! Getting a presentation's videos ready before LaTeX runs, for `\usepackage{texoravideo}`.
+//!
+//! TeXora ships the package (`assets/tex/texoravideo.sty`) and puts its folder in TEXINPUTS while it
+//! compiles, so there is nothing to install or copy. Before each compile it finds every
+//! `\includevideo{...}`, finds the file, and makes the clip's poster: `texora-video/<MD5>.jpg` beside
+//! the presentation, where MD5 is that of the clip's path (the package works out the same name).
+//!
+//! The path is read exactly as written, from the presentation's folder: `{clip.mp4}` is beside the
+//! .tex file and `{videos/clip.mp4}` is in its `videos` folder (any folder name). Each video has one
+//! poster, however often it is used; if uses ask for different `posterat` values, the
+//! first one counts and the others are reported. A poster is made again only when its clip's size or
+//! modification time changes; what was found is kept in `texora-video/index.json`, which stays with
+//! the PDF so it plays when opened later. Posters no longer used are removed.
+//!
+//! Safety: paths come from the document, so only files inside the presentation's folder are used
+//! (no absolute paths, no `..` out of it, no links leading out, no web addresses), and files are opened
+//! directly by the decoder; no command is ever built from them.
+use crate::video::{self, Problem};
+use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+use std::path::{Component, Path, PathBuf};
+
+pub const STY: &str = include_str!("../assets/tex/texoravideo.sty");
+pub const FOLDER: &str = "texora-video";
+/// Posters are at most this wide; a bigger one only makes the PDF larger.
+const POSTER_MAX_WIDTH: u32 = 1280;
+
+/// One `\includevideo` in the source.
+#[derive(Clone, Debug, PartialEq)]
+pub struct Use {
+    /// The path as written, with runs of spaces made one, as TeX reads it.
+    pub path: String,
+    /// `posterat`, in percent, when this use gives one.
+    pub at: Option<u32>,
+    /// Line in the file it is in (from 1).
+    pub line: usize,
+    pub file: PathBuf,
+}
+
+/// What `index.json` keeps about each poster.
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
+pub struct Entry {
+    pub path: String,
+    pub at: u32,
+    pub size: u64,
+    /// Modification time, in seconds since 1970.
+    pub modified: u64,
+    pub width: u32,
+    pub height: u32,
+    pub duration: f64,
+    /// Why it cannot be played, if so (the words shown over its poster).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub problem: Option<String>,
+    /// Something worth knowing that does not stop it playing (listed under Problems).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub note: Option<String>,
+}
+
+#[derive(Clone, Debug, Default, Serialize, Deserialize)]
+pub struct Index {
+    /// By poster file name.
+    pub posters: BTreeMap<String, Entry>,
+}
+
+/// What getting ready did, for the compile report.
+#[derive(Clone, Debug, Default, PartialEq)]
+pub struct Report {
+    pub made: usize,
+    pub reused: usize,
+    /// Each clip that cannot be played: the file and line of its `\includevideo`, and the words.
+    pub problems: Vec<(PathBuf, usize, String)>,
+}
+
+/// MD5 in capitals, as `\pdf@mdfivesum` writes it.
+pub fn md5_upper(s: &str) -> String {
+    use md5::{Digest, Md5};
+    Md5::digest(s.as_bytes()).iter().map(|b| format!("{b:02X}")).collect()
+}
+
+/// The poster's file name for a clip's path (as found: `clip.mp4` or `media/clip.mp4`), the same one
+/// the package computes. One poster per video.
+pub fn poster_name(path: &str) -> String {
+    format!("{}.jpg", md5_upper(path))
+}
+
+/// Whether a file in `texora-video/` is a poster TeXora made (an MD5 in capitals and `.jpg`).
+/// Older versions named a poster taken partway in `<MD5>-<percent>.jpg`; those are TeXora's too.
+fn is_poster_file(name: &str) -> bool {
+    let Some(stem) = name.strip_suffix(".jpg") else { return false };
+    let (hash, rest) = stem.split_at(stem.len().min(32));
+    let hex = hash.len() == 32 && hash.bytes().all(|b| b.is_ascii_digit() || (b'A'..=b'F').contains(&b));
+    let old_suffix = rest.is_empty() || rest.strip_prefix('-').is_some_and(|p| !p.is_empty() && p.len() <= 2 && p.bytes().all(|b| b.is_ascii_digit()));
+    hex && old_suffix
+}
+
+/// The folder holding the package; it is made (or refreshed) when needed. Its path never holds a
+/// doubled separator, since TeX would read `//` as "search every folder below".
+pub fn tex_dir() -> std::io::Result<PathBuf> {
+    let dir = crate::settings::data_dir().join("tex");
+    std::fs::create_dir_all(&dir)?;
+    let dir = dir.canonicalize().unwrap_or(dir);
+    write_if_changed(&dir.join("texoravideo.sty"), STY.as_bytes())?;
+    write_if_changed(&dir.join("texoravideo-placeholder.png"), &placeholder_png())?;
+    Ok(dir)
+}
+
+fn write_if_changed(p: &Path, bytes: &[u8]) -> std::io::Result<()> {
+    if std::fs::read(p).ok().as_deref() != Some(bytes) {
+        std::fs::write(p, bytes)?;
+    }
+    Ok(())
+}
+
+/// TEXINPUTS with TeXora's package folder first and the usual places after it (the empty entry at the
+/// end means "and the default search path").
+pub fn texinputs(dir: &Path) -> std::ffi::OsString {
+    let sep = if cfg!(windows) { ";" } else { ":" };
+    let mut s = std::ffi::OsString::from(dir.as_os_str());
+    s.push(sep);
+    if let Some(old) = std::env::var_os("TEXINPUTS") {
+        s.push(&old);
+        if !old.to_string_lossy().ends_with(sep) {
+            s.push(sep);
+        }
+    }
+    s
+}
+
+/// A plain dark 16:9 picture with a play sign, used when a clip has no poster (missing, refused or
+/// unsupported). TeXora writes the reason over it.
+pub fn placeholder_png() -> Vec<u8> {
+    let (w, h) = (640u32, 360u32);
+    let mut px = vec![0u8; (w * h * 4) as usize];
+    let (cx, cy, r) = (w as f32 / 2.0, h as f32 / 2.0, 54.0f32);
+    for y in 0..h {
+        for x in 0..w {
+            let (fx, fy) = (x as f32 + 0.5 - cx, y as f32 + 0.5 - cy);
+            let mut c = [43u8, 47, 51];
+            if (fx * fx + fy * fy).sqrt() < r {
+                c = [70, 76, 82];
+                // A triangle pointing right, inside the circle.
+                let (tx, ty) = (fx + 8.0, fy);
+                if tx > -18.0 && tx < 26.0 && ty.abs() < (26.0 - tx) * 0.62 {
+                    c = [225, 228, 230];
+                }
+            }
+            let o = ((y * w + x) * 4) as usize;
+            px[o..o + 4].copy_from_slice(&[c[0], c[1], c[2], 255]);
+        }
+    }
+    crate::pdf::encode_png(w, h, &px).unwrap_or_default()
+}
+
+/// Leaves out comments: a `%` not written as `\%` ends the line's text.
+fn uncomment(src: &str) -> String {
+    src.lines()
+        .map(|l| {
+            let b = l.as_bytes();
+            let end = (0..b.len()).find(|&i| b[i] == b'%' && (i == 0 || b[i - 1] != b'\\')).unwrap_or(b.len());
+            &l[..end]
+        })
+        .collect::<Vec<_>>()
+        .join("\n")
+}
+
+/// The text inside a balanced pair starting at `open` (`[` or `{`), and where it ends.
+fn balanced(s: &str, open: usize) -> Option<(&str, usize)> {
+    let (o, c) = match s.as_bytes()[open] {
+        b'[' => (b'[', b']'),
+        _ => (b'{', b'}'),
+    };
+    let mut depth = 0i32;
+    let mut braces = 0i32;
+    for (i, &b) in s.as_bytes().iter().enumerate().skip(open) {
+        if o == b'[' {
+            // Brackets inside braces do not count: [width={a]b}].
+            match b {
+                b'{' => braces += 1,
+                b'}' => braces -= 1,
+                b'[' if braces == 0 => depth += 1,
+                b']' if braces == 0 => {
+                    depth -= 1;
+                    if depth == 0 {
+                        return Some((&s[open + 1..i], i + 1));
+                    }
+                }
+                _ => {}
+            }
+        } else if b == o {
+            depth += 1;
+        } else if b == c {
+            depth -= 1;
+            if depth == 0 {
+                return Some((&s[open + 1..i], i + 1));
+            }
+        }
+    }
+    None
+}
+
+/// The `key=value` pairs of a video options list.
+pub fn options(list: &str) -> Vec<(String, String)> {
+    list.split(',').filter(|p| !p.trim().is_empty()).map(|p| match p.split_once('=') {
+        Some((k, v)) => (k.trim().to_string(), v.trim().to_string()),
+        None => (p.trim().to_string(), "true".to_string()),
+    }).collect()
+}
+
+/// Every `\includevideo` in one file's text.
+pub fn uses_in(src: &str, file: &Path) -> Vec<Use> {
+    let clean = uncomment(src);
+    let mut out = vec![];
+    let name = "\\includevideo";
+    let mut pos = 0;
+    while let Some(p) = clean[pos..].find(name) {
+        let start = pos + p;
+        let mut i = start + name.len();
+        pos = i;
+        if clean[i..].starts_with(|c: char| c.is_ascii_alphabetic()) {
+            continue;
+        }
+        let mut opts: Vec<&str> = vec![];
+        let b = clean.as_bytes();
+        loop {
+            while i < b.len() && b[i].is_ascii_whitespace() {
+                i += 1;
+            }
+            if i < b.len() && b[i] == b'[' && opts.len() < 2 {
+                let Some((inner, end)) = balanced(&clean, i) else { break };
+                opts.push(inner);
+                i = end;
+                continue;
+            }
+            break;
+        }
+        if i >= b.len() || b[i] != b'{' {
+            continue;
+        }
+        let Some((arg, end)) = balanced(&clean, i) else { continue };
+        pos = end;
+        // TeX reads any run of spaces or line ends as one space.
+        let path = arg.split_whitespace().collect::<Vec<_>>().join(" ");
+        let path = if arg.starts_with(char::is_whitespace) { format!(" {path}") } else { path };
+        let at = opts.get(1).map(|o| options(o)).unwrap_or_default().iter().find(|(k, _)| k == "posterat").and_then(|(_, v)| v.trim_end_matches('%').trim().parse::<f64>().ok()).map(|v| v.clamp(0.0, 99.0) as u32);
+        let line = clean[..start].matches('\n').count() + 1;
+        out.push(Use { path, at, line, file: file.to_path_buf() });
+    }
+    out
+}
+
+/// Every `\includevideo` of a document: the main file and the files it `\input`s or `\include`s,
+/// inside its folder.
+pub fn uses(root: &Path) -> Vec<Use> {
+    let dir = root.parent().unwrap_or(Path::new("."));
+    let mut out = vec![];
+    let mut seen: Vec<PathBuf> = vec![];
+    let mut todo = vec![root.to_path_buf()];
+    while let Some(f) = todo.pop() {
+        if seen.contains(&f) || seen.len() > 200 {
+            continue;
+        }
+        seen.push(f.clone());
+        let Ok(src) = std::fs::read_to_string(&f) else { continue };
+        out.extend(uses_in(&src, &f));
+        let clean = uncomment(&src);
+        for cmd in ["\\input{", "\\include{", "\\subfile{"] {
+            for (k, _) in clean.match_indices(cmd) {
+                let open = k + cmd.len() - 1;
+                if let Some((name, _)) = balanced(&clean, open) {
+                    let name = name.trim();
+                    if let Ok(p) = resolve(dir, name) {
+                        todo.push(p);
+                    } else if let Ok(p) = resolve(dir, &format!("{name}.tex")) {
+                        todo.push(p);
+                    }
+                }
+            }
+        }
+    }
+    out
+}
+
+/// The file a path written in the document means, if it may be used: inside the presentation's
+/// folder `dir`, and a file.
+pub fn resolve(dir: &Path, written: &str) -> Result<PathBuf, Problem> {
+    let w = written.trim();
+    if w.is_empty() {
+        return Err(Problem::Refused("No file name was given.".into()));
+    }
+    if w.contains("://") || w.starts_with("www.") {
+        return Err(Problem::Refused("Web addresses are not played. Save the video in the presentation's folder.".into()));
+    }
+    let rel = Path::new(w);
+    let drive = w.len() > 1 && w.as_bytes()[1] == b':';
+    if rel.is_absolute() || rel.has_root() || drive || w.starts_with('~') {
+        return Err(Problem::Refused("Only files inside the presentation's folder are played. Write the path from that folder.".into()));
+    }
+    if rel.components().any(|c| matches!(c, Component::ParentDir)) {
+        return Err(Problem::Refused("The path leads out of the presentation's folder (\"..\").".into()));
+    }
+    let base = dir.canonicalize().unwrap_or_else(|_| dir.to_path_buf());
+    let full = base.join(rel);
+    if !full.exists() {
+        return Err(Problem::Missing);
+    }
+    // A link inside the folder that points out of it is refused too.
+    let real = full.canonicalize().map_err(|e| Problem::Broken(e.to_string()))?;
+    if !real.starts_with(&base) {
+        return Err(Problem::Refused("It is a link to a file outside the presentation's folder.".into()));
+    }
+    if !real.is_file() {
+        return Err(Problem::Refused("It is a folder, not a file.".into()));
+    }
+    Ok(real)
+}
+
+/// The clip written as `written`: the path is read exactly as written, from the presentation's folder
+/// (`clip.mp4` beside it, `videos/clip.mp4` in a folder inside it). Returns the file and the path,
+/// which names its poster.
+pub fn locate(dir: &Path, written: &str) -> Result<(PathBuf, String), Problem> {
+    resolve(dir, written.trim()).map(|f| (f, written.to_string()))
+}
+
+fn stamp(p: &Path) -> (u64, u64) {
+    let m = std::fs::metadata(p).ok();
+    let size = m.as_ref().map(|m| m.len()).unwrap_or(0);
+    let modified = m.and_then(|m| m.modified().ok()).and_then(|t| t.duration_since(std::time::UNIX_EPOCH).ok()).map(|d| d.as_secs()).unwrap_or(0);
+    (size, modified)
+}
+
+/// Whether a clip is the same as when its index entry was written (same size and modification time).
+pub fn unchanged(e: &Entry, file: &Path) -> bool {
+    let (size, modified) = stamp(file);
+    e.size == size && e.modified == modified
+}
+
+pub fn read_index(dir: &Path) -> Index {
+    std::fs::read(dir.join(FOLDER).join("index.json")).ok().and_then(|b| serde_json::from_slice(&b).ok()).unwrap_or_default()
+}
+
+/// A JPEG of an RGBA picture, made smaller if wider than posters need to be.
+fn poster_jpeg(w: u32, h: u32, rgba: Vec<u8>) -> Option<Vec<u8>> {
+    let img = image::RgbaImage::from_raw(w, h, rgba)?;
+    let img = if w > POSTER_MAX_WIDTH {
+        image::imageops::resize(&img, POSTER_MAX_WIDTH, (h as u64 * POSTER_MAX_WIDTH as u64 / w as u64).max(1) as u32, image::imageops::FilterType::Triangle)
+    } else {
+        img
+    };
+    let rgb = image::DynamicImage::ImageRgba8(img).to_rgb8();
+    let mut out = vec![];
+    image::codecs::jpeg::JpegEncoder::new_with_quality(&mut out, 88).encode_image(&rgb).ok()?;
+    Some(out)
+}
+
+/// Gets every clip of the document `root` ready: checks it and makes its poster unless an up-to-date
+/// one is there. Clips are worked on side by side.
+pub fn prepare(root: &Path) -> Report {
+    let uses = uses(root);
+    let mut report = Report::default();
+    if uses.is_empty() {
+        return report;
+    }
+    let dir = root.parent().unwrap_or(Path::new(".")).to_path_buf();
+    let out_dir = dir.join(FOLDER);
+    if std::fs::create_dir_all(&out_dir).is_err() {
+        return report;
+    }
+    let old = read_index(&dir);
+    // One job per video, wherever it is used and however it is written: `clip.mp4` and
+    // `media/clip.mp4` are the same clip when it is in `media`. The first `posterat` given counts.
+    struct Job {
+        key: String,
+        found: Result<PathBuf, Problem>,
+        at: u32,
+        uses: Vec<usize>,
+    }
+    let mut jobs: Vec<Job> = vec![];
+    for (i, u) in uses.iter().enumerate() {
+        let found = locate(&dir, &u.path);
+        let key = found.as_ref().map(|(_, k)| k.clone()).unwrap_or_else(|_| u.path.clone());
+        match jobs.iter_mut().find(|j| j.key == key) {
+            Some(j) => j.uses.push(i),
+            None => jobs.push(Job { key, found: found.map(|(f, _)| f), at: 0, uses: vec![i] }),
+        }
+    }
+    for j in &mut jobs {
+        let first = j.uses.iter().find_map(|&i| uses[i].at.map(|a| (i, a)));
+        if let Some((fi, at)) = first {
+            j.at = at;
+            for &i in &j.uses {
+                if let Some(other) = uses[i].at.filter(|&a| a != at) {
+                    let u = &uses[i];
+                    report.problems.push((u.file.clone(), u.line, format!("posterat={other} is not used: {} has one poster, taken at {at}% as asked on line {}.", j.key, uses[fi].line)));
+                }
+            }
+        }
+    }
+    let results: Vec<(String, Entry, bool)> = std::thread::scope(|s| {
+        let handles: Vec<_> = jobs
+            .iter()
+            .map(|j| {
+                let (out_dir, old) = (&out_dir, &old);
+                s.spawn(move || {
+                    let name = poster_name(&j.key);
+                    let mut e = Entry { path: j.key.clone(), at: j.at, ..Default::default() };
+                    let file = match &j.found {
+                        Ok(f) => f.clone(),
+                        Err(p) => {
+                            e.problem = Some(p.message(&j.key));
+                            return (name, e, false);
+                        }
+                    };
+                    (e.size, e.modified) = stamp(&file);
+                    let target = out_dir.join(&name);
+                    if let Some(prev) = old.posters.get(&name) {
+                        if prev.size == e.size && prev.modified == e.modified && prev.at == e.at && prev.problem.is_none() && target.is_file() {
+                            return (name, prev.clone(), true);
+                        }
+                    }
+                    match video::poster(&file, j.at as f64 / 100.0) {
+                        Ok((w, h, rgba)) => {
+                            (e.width, e.height) = (w, h);
+                            let saved = poster_jpeg(w, h, rgba).is_some_and(|jpg| std::fs::write(&target, jpg).is_ok());
+                            if !saved {
+                                e.problem = Some(Problem::Broken("Its poster could not be saved.".into()).message(&j.key));
+                            }
+                        }
+                        // VLC plays the clip, but only ffmpeg makes posters: a plain box shows instead.
+                        Err(Problem::NeedsPlayer) if matches!(video::backend(), video::Backend::Vlc(_)) => {
+                            e.note = Some(format!("No poster for {}: posters need ffmpeg, so a plain box shows. The clip plays in VLC when clicked.", j.key));
+                        }
+                        Err(p) => {
+                            e.problem = Some(p.message(&j.key));
+                        }
+                    }
+                    (name, e, false)
+                })
+            })
+            .collect();
+        handles.into_iter().filter_map(|h| h.join().ok()).collect()
+    });
+    let mut index = Index::default();
+    for (name, e, reused) in results {
+        if reused {
+            report.reused += 1;
+        } else if e.problem.is_none() {
+            report.made += 1;
+        }
+        if let Some(p) = e.problem.as_ref().or(e.note.as_ref()) {
+            for &i in &jobs.iter().find(|j| j.key == e.path).map(|j| j.uses.clone()).unwrap_or_default() {
+                let u = &uses[i];
+                report.problems.push((u.file.clone(), u.line, p.replace('\n', " ")));
+            }
+        }
+        index.posters.insert(name, e);
+    }
+    report.problems.sort_by(|a, b| (&a.0, a.1).cmp(&(&b.0, b.1)));
+    // Only the posters in use stay: one per video, none for a clip that cannot be played.
+    if let Ok(list) = std::fs::read_dir(&out_dir) {
+        for f in list.flatten() {
+            let n = f.file_name().to_string_lossy().to_string();
+            let wanted = index.posters.get(&n).is_some_and(|e| e.problem.is_none());
+            if is_poster_file(&n) && !wanted {
+                let _ = std::fs::remove_file(f.path());
+            }
+        }
+    }
+    if let Ok(json) = serde_json::to_vec_pretty(&index) {
+        let _ = std::fs::write(out_dir.join("index.json"), json);
+    }
+    report
+}
+
+/// A clip as a link in the PDF says: `texora-video:a<0|1>l<0|1>m<0|1>p<percent>:<path>`.
+#[derive(Clone, Debug, PartialEq)]
+pub struct LinkClip {
+    pub path: String,
+    pub autoplay: bool,
+    pub repeat: bool,
+    pub mute: bool,
+    pub at: u32,
+}
+
+pub fn parse_link(uri: &str) -> Option<LinkClip> {
+    let rest = uri.strip_prefix("texora-video:")?;
+    let (flags, path) = rest.split_once(':')?;
+    let flag = |c: char| flags.find(c).and_then(|i| flags[i + 1..].chars().next()) == Some('1');
+    let at = flags.find('p').map(|i| flags[i + 1..].chars().take_while(|c| c.is_ascii_digit()).collect::<String>()).and_then(|s| s.parse().ok()).unwrap_or(0);
+    Some(LinkClip { path: percent_decode(path), autoplay: flag('a'), repeat: flag('l'), mute: flag('m'), at })
+}
+
+/// Undoes `%XX` escapes, which some viewers' copies of a link have; other text is left as it is.
+fn percent_decode(s: &str) -> String {
+    let b = s.as_bytes();
+    let mut out = Vec::with_capacity(b.len());
+    let mut i = 0;
+    while i < b.len() {
+        if b[i] == b'%' && i + 3 <= b.len() {
+            if let Some(v) = std::str::from_utf8(&b[i + 1..i + 3]).ok().and_then(|h| u8::from_str_radix(h, 16).ok()) {
+                out.push(v);
+                i += 3;
+                continue;
+            }
+        }
+        out.push(b[i]);
+        i += 1;
+    }
+    String::from_utf8(out).unwrap_or_else(|_| s.to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn poster_names_match_the_package() {
+        // The same values pdfTeX, XeTeX and LuaTeX give (see the package).
+        assert_eq!(poster_name("test.mp4"), "1A156A436A2D37E2343AC6BD9CDA5686.jpg");
+        assert_eq!(poster_name("média/Clip été (1) & more_x.mp4"), "730843651C848A99311D2B74132437A1.jpg");
+        assert_eq!(poster_name("فيديو/مقطع.mp4"), "9EDE6849DA6808BFD1AD659703C57605.jpg");
+        assert!(is_poster_file("1A156A436A2D37E2343AC6BD9CDA5686.jpg") && !is_poster_file("index.json") && !is_poster_file("cover.jpg"));
+        assert!(is_poster_file("1A156A436A2D37E2343AC6BD9CDA5686-50.jpg"), "old names are cleaned up too");
+        assert!(!is_poster_file("1A156A436A2D37E2343AC6BD9CDA5686-cover.jpg"));
+    }
+
+    #[test]
+    fn uses_are_read_with_both_optional_arguments() {
+        let src = "% \\includevideo{commented.mp4}\n\\begin{frame}\n  \\includevideo[width=0.5\\textwidth]{test.mp4}\n  \\includevideo[height=5cm][loop, posterat=25]{media/clip  one.gif}\n  \\includevideo[width={a]b}][poster=cover.png,autoplay=false]{vidéo é.mp4}\\pause\n  \\includevideos{not-this}\n\\end{frame}";
+        let u = uses_in(src, Path::new("x.tex"));
+        let got: Vec<(&str, Option<u32>, usize)> = u.iter().map(|u| (u.path.as_str(), u.at, u.line)).collect();
+        assert_eq!(got, vec![("test.mp4", None, 3), ("media/clip one.gif", Some(25), 4), ("vidéo é.mp4", None, 5)]);
+    }
+
+    #[test]
+    fn unsafe_paths_are_refused() {
+        let dir = std::env::temp_dir().join("texora-resolve-test");
+        std::fs::create_dir_all(dir.join("media")).unwrap();
+        std::fs::write(dir.join("media/ok.mp4"), b"x").unwrap();
+        assert!(resolve(&dir, "media/ok.mp4").is_ok());
+        for bad in ["/etc/passwd", "../outside.mp4", "media/../../x.mp4", "https://example.com/a.mp4", "C:/Windows/x.mp4", "~/x.mp4", "media"] {
+            assert!(matches!(resolve(&dir, bad), Err(Problem::Refused(_))), "{bad} should be refused: {:?}", resolve(&dir, bad));
+        }
+        assert_eq!(resolve(&dir, "nothing.mp4"), Err(Problem::Missing));
+        #[cfg(unix)]
+        {
+            let _ = std::fs::remove_file(dir.join("out.mp4"));
+            std::os::unix::fs::symlink("/etc/hosts", dir.join("out.mp4")).unwrap();
+            assert!(matches!(resolve(&dir, "out.mp4"), Err(Problem::Refused(_))));
+        }
+    }
+
+    #[test]
+    fn links_are_read() {
+        let l = parse_link("texora-video:a1l0m1p25:vidéos/été (1) & more.mp4").unwrap();
+        assert_eq!(l, LinkClip { path: "vidéos/été (1) & more.mp4".into(), autoplay: true, repeat: false, mute: true, at: 25 });
+        assert_eq!(parse_link("texora-video:a0l1m0p0:my%20clip.mp4").unwrap().path, "my clip.mp4");
+        assert!(parse_link("https://example.com").is_none());
+    }
+
+    /// Uses GIFs only, which TeXora decodes itself, so it gives the same result on every computer,
+    /// with or without ffmpeg or VLC (the test machines on GitHub have neither).
+    #[test]
+    fn posters_are_made_once_and_problems_reported() {
+        let dir = std::env::temp_dir().join(format!("texora-prep-{}", std::process::id()));
+        std::fs::create_dir_all(dir.join("media")).unwrap();
+        let src = Path::new(env!("CARGO_MANIFEST_DIR")).join("assets/test/video");
+        std::fs::copy(src.join("test.gif"), dir.join("wave.gif")).unwrap();
+        std::fs::copy(src.join("test.gif"), dir.join("media/clip é.gif")).unwrap();
+        std::fs::copy(src.join("test.txt"), dir.join("test.txt")).unwrap();
+        // A poster left from an older compile, which is no longer used.
+        std::fs::create_dir_all(dir.join(FOLDER)).unwrap();
+        std::fs::write(dir.join(FOLDER).join("0123456789ABCDEF0123456789ABCDEF.jpg"), b"old").unwrap();
+        let tex = dir.join("deck.tex");
+        std::fs::write(&tex, "\\includevideo[][posterat=30]{wave.gif}\n\\includevideo[][posterat=50]{wave.gif}\n\\includevideo{media/clip é.gif}\n\\includevideo{does-not-exist.mp4}\n\\includevideo{test.txt}\n\\includevideo{../escape.mp4}\n\\includevideo{media/clip é.gif}\n\\includevideo{wave.gif}\n").unwrap();
+        let r = prepare(&tex);
+        assert_eq!((r.made, r.reused), (2, 0), "one poster per video: {r:?}");
+        let lines: Vec<usize> = r.problems.iter().map(|p| p.1).collect();
+        assert_eq!(lines, vec![2, 4, 5, 6], "{:?}", r.problems);
+        assert!(r.problems[0].2.contains("posterat=50 is not used") && r.problems[0].2.contains("30%"));
+        assert_eq!(r.problems[1].2, "Video not found: Place the video in the same folder as your .tex file or in a subfolder. If it's in a subfolder, include the folder path in \\includevideo.");
+        assert!(r.problems[2].2.contains("Not a video"), "{}", r.problems[2].2);
+        assert!(r.problems[3].2.contains("out of"));
+        // Each GIF, used two or three times, has one poster; the old one is gone.
+        let posters: Vec<String> = std::fs::read_dir(dir.join(FOLDER)).unwrap().flatten().map(|f| f.file_name().to_string_lossy().to_string()).filter(|n| n.ends_with(".jpg")).collect();
+        assert_eq!(posters.len(), 2, "{posters:?}");
+        assert!(dir.join(FOLDER).join(poster_name("wave.gif")).is_file());
+        assert!(dir.join(FOLDER).join(poster_name("media/clip é.gif")).is_file());
+        let again = prepare(&tex);
+        assert_eq!((again.made, again.reused), (0, 2), "unchanged clips are not made again");
+        let idx = read_index(&dir);
+        assert_eq!((idx.posters[&poster_name("wave.gif")].width, idx.posters[&poster_name("wave.gif")].at), (320, 30));
+        assert!(idx.posters[&poster_name("does-not-exist.mp4")].problem.is_some());
+    }
+
+    /// An MP4's poster needs ffmpeg, so this runs only where it is installed.
+    #[test]
+    fn mp4_posters_are_made_with_installed_ffmpeg() {
+        if video::find_ffmpeg().is_none() {
+            return;
+        }
+        let dir = std::env::temp_dir().join(format!("texora-prep-mp4-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        std::fs::copy(Path::new(env!("CARGO_MANIFEST_DIR")).join("assets/test/video/test.mp4"), dir.join("test.mp4")).unwrap();
+        let tex = dir.join("deck.tex");
+        std::fs::write(&tex, "\\includevideo[][posterat=30]{test.mp4}\n\\includevideo{test.mp4}\n").unwrap();
+        let r = prepare(&tex);
+        assert_eq!((r.made, r.reused, r.problems.len()), (1, 0, 0), "{r:?}");
+        let idx = read_index(&dir);
+        assert_eq!((idx.posters[&poster_name("test.mp4")].width, idx.posters[&poster_name("test.mp4")].at), (640, 30));
+    }
+
+    /// A presentation can never choose which program runs or add to its arguments: the player and its
+    /// path come only from TeXora's own Settings. Here a project tries every place it controls.
+    #[test]
+    fn a_project_cannot_set_the_player_or_its_arguments() {
+        let before = video::tools();
+        let dir = std::env::temp_dir().join(format!("texora-hostile-{}", std::process::id()));
+        std::fs::create_dir_all(dir.join(FOLDER)).unwrap();
+        // A settings file in the project, an index.json with extra fields, and a .tex that names
+        // programs and options in every way it can.
+        let evil = r#"{"video_player":"vlc","ffmpeg_path":"/bin/sh","vlc_path":"/bin/sh","check_updates":false}"#;
+        std::fs::write(dir.join("settings.json"), evil).unwrap();
+        std::fs::write(dir.join(FOLDER).join("index.json"), r#"{"posters":{},"ffmpeg_path":"/bin/sh","args":["-f","lavfi"]}"#).unwrap();
+        let tex = dir.join("talk.tex");
+        std::fs::write(&tex, "% !TEX program = /bin/sh\n% ffmpeg_path = /bin/sh\n\\includevideo[][autoplay,ffmpeg=/bin/sh,args=-f lavfi]{--ffmpeg=/bin/sh}\n\\includevideo{-i http://example.com/x.mp4}\n").unwrap();
+        std::fs::write(dir.join("--ffmpeg=%2Fbin%2Fsh"), b"x").unwrap();
+        let r = prepare(&tex);
+        assert!(r.problems.iter().all(|p| !p.2.is_empty()));
+        let after = video::tools();
+        assert_eq!((after.choice, after.ffmpeg, after.vlc), (before.choice, before.ffmpeg, before.vlc), "the project changed nothing");
+        // The engine named in the .tex is one of three built-in names, never a program path.
+        assert_eq!(crate::latex::detect_engine("% !TEX program = /bin/sh\n"), crate::latex::Engine::PdfLatex);
+        // A link in a PDF carries flags and a path, nothing else, and the path stays inside the folder.
+        let l = parse_link("texora-video:a1l1m1p5 -f lavfi -i /bin/sh:../../bin/sh").unwrap();
+        assert_eq!((l.autoplay, l.repeat, l.mute, l.at), (true, true, true, 5));
+        assert!(matches!(resolve(&dir, &l.path), Err(Problem::Refused(_))));
+        // A file whose name looks like an option is only ever a full path, after `-i` or `--`.
+        let odd = resolve(&dir, "--ffmpeg=%2Fbin%2Fsh").unwrap();
+        let input = video::ffmpeg_input_args(&odd, None).unwrap().last().unwrap().clone();
+        assert!(input.starts_with("file:") && !input.starts_with("file:-") && input.ends_with("--ffmpeg=%2Fbin%2Fsh"), "{input}");
+        let v = video::vlc_args(&odd, false).unwrap();
+        assert_eq!(v[1], "--");
+        assert!(!v[2].starts_with('-') && v[2].ends_with("--ffmpeg=%2Fbin%2Fsh"), "{}", v[2]);
+    }
+
+    #[test]
+    fn the_path_is_read_as_written_in_any_subfolder() {
+        let dir = std::env::temp_dir().join(format!("texora-locate-{}", std::process::id()));
+        std::fs::create_dir_all(dir.join("my videos/2026")).unwrap();
+        std::fs::write(dir.join("beside.mp4"), b"x").unwrap();
+        std::fs::write(dir.join("my videos/2026/inside.mp4"), b"x").unwrap();
+        assert_eq!(locate(&dir, "beside.mp4").unwrap().1, "beside.mp4");
+        assert_eq!(locate(&dir, "my videos/2026/inside.mp4").unwrap().1, "my videos/2026/inside.mp4");
+        // A clip in a folder must be written with its folder: TeXora does not search for it.
+        assert_eq!(locate(&dir, "inside.mp4"), Err(Problem::Missing));
+        assert_eq!(locate(&dir, "my videos/beside.mp4"), Err(Problem::Missing));
+        assert!(matches!(locate(&dir, "../beside.mp4"), Err(Problem::Refused(_))));
+    }
+}