Lecture Lens

Turn the lectures you attend online into transcripts, slide-linked notes and flashcards, on your own Mac, with local models. Nothing is uploaded.

Lecture Lens is a study toolkit and a small native macOS app. It reads what screenpipe captures while you watch a recorded lecture or sit in a live class, and builds study material from it with a model running on your machine.

Status: early, single-maintainer, macOS on Apple silicon only. It works for the author's weekly classes; expect rough edges.

What it does

You do	Lecture Lens does
Watch a recorded lecture in the browser	Records the lecture's audio, pauses screen capture on copy-protected players, logs which page you were on
Sit in a live class in a meeting app	Captures slides and audio, picks the distinct slides, describes them with a vision model
Click Build	Writes a timecoded transcript, notes with slide and time citations, and flashcards
Ask a question	Answers from your own captures, with sources
Change a prompt or a model	Runs a local evaluation so you can see whether quality moved

What it does not do

• It does not record copy-protected video. On those pages it keeps audio only.
• It does not send anything to a cloud service. Evaluation runs with a local judge model.
• It does not include screenpipe or any course material. You bring both.

How it fits together

 Lecture Lens.app (SwiftUI)        start/stop capture, lectures, ask, evals
        │  argv in, JSON out
 toolkit (zsh + Python)            sp-start · sp-mode · lecture · study · tests/evals
        │  HTTP on 127.0.0.1, local files
 screenpipe (you install)  ·  local model server (you install)  ·  your files

Requirements

• macOS 15 or later on Apple silicon; 32 GB of memory or more is realistic for the models.
• screenpipe, installed and licensed by you. Read its licence: it is not open source, and Lecture Lens does not change that.
• A local OpenAI-compatible model server with a text model, a vision-capable model and, for evaluation, a second model as judge.
• Python 3.11+ with Pillow, ffmpeg, and Xcode command line tools for the app.

Quick start

git clone https://github.com/opnsrcntrbtr/screenpipe.git ~/lecture-lens
cd ~/lecture-lens
tools/setup_hooks.sh                 # content guard hooks (required before you commit)
cp .env.example .env                 # set your model ids and your course portal's host
cp allowed-domains.example.txt allowed-domains.txt
python3 -m venv .venv && .venv/bin/pip install -r requirements-dev.txt
./check.sh                           # unit tests and contract checks
app/build_app.sh --test --open       # build and open the app

Then, in the app: Start capture, attend the lecture, Stop, and Build the session under Lectures. From a terminal:

./lecture list --since 7d
./lecture build last
./lecture build --from 10:00 --to 11:30 --title "Week 3 live class"   # live classes
./study ask "what did the lecture say about evaluation?"

Capture must be started from the app, not from a shell: macOS ties recording permission to the app that launches the recorder.

Evaluation

tests/evals/run.sh --smoke     # 6 fixed cases, about 12 minutes on a local judge
tests/evals/run.sh             # full suite; over an hour
tests/evals/run_judge_bench.sh # how far to trust the judge

Evaluations refuse to start while a live class is being captured, because they swap the model.

Keeping course material out of this repository

This is a public repository about a private activity. Three layers keep them apart:

1. .gitignore excludes capture output, decks, recordings and local configuration.
2. tools/content_guard.py scans every commit and file before a push for blocked names (stored only as hashes), forbidden file types, secrets and personal data. It runs as pre-commit, commit-msg and pre-push hooks.
3. A plain git push is disabled; tools/publish.sh runs the guard and then pushes. CI runs the guard again.

A hook can be bypassed by someone determined to, and a hash list can be guessed against. The guard prevents accidents; it is not a legal review.

Documentation

The docs site is built with Docusaurus from website/: getting started, capture guides, evaluation, architecture, decisions, the roadmap, the design review and the tech-debt register.

cd website && npm ci && npm start

Licence and names

Apache-2.0; see LICENSE and NOTICE. Lecture Lens is independent and unaffiliated with any university, course provider, platform or the makers of screenpipe. This README is not legal advice.