Use segment title as fallback for returned tag title

Some applications like handbrake store the title only in the segment
info element.

Author: ufleisch

taglib/matroska/ebml/ebmlelement.cpp

@@ -91,6 +91,7 @@ std::unique_ptr<EBML::Element> EBML::Element::factory(File &file)
     RETURN_ELEMENT_FOR_CASE(Id::MkAttachedFileData);
     RETURN_ELEMENT_FOR_CASE(Id::MkSeekID);
     RETURN_ELEMENT_FOR_CASE(Id::MkDuration);
+    RETURN_ELEMENT_FOR_CASE(Id::MkTitle);
     RETURN_ELEMENT_FOR_CASE(Id::MkSamplingFrequency);
     RETURN_ELEMENT_FOR_CASE(Id::MkSeekHead);
     RETURN_ELEMENT_FOR_CASE(Id::VoidElement);

taglib/matroska/ebml/ebmlelement.h

@@ -75,6 +75,7 @@ namespace TagLib::EBML {
       MkInfo                    = 0x1549A966,
       MkTimestampScale          = 0x2AD7B1,
       MkDuration                = 0x4489,
+      MkTitle                   = 0x7BA9,
       MkTracks                  = 0x1654AE6B,
       MkTrackEntry              = 0xAE,
       MkCodecID                 = 0x86,
@@ -186,6 +187,7 @@ namespace TagLib::EBML {
   template <> struct GetElementTypeById<Element::Id::MkTagBinary> { using type = BinaryElement; };
   template <> struct GetElementTypeById<Element::Id::MkCodecState> { using type = BinaryElement; };
   template <> struct GetElementTypeById<Element::Id::MkDuration> { using type = FloatElement; };
+  template <> struct GetElementTypeById<Element::Id::MkTitle> { using type = UTF8StringElement; };
   template <> struct GetElementTypeById<Element::Id::MkSamplingFrequency> { using type = FloatElement; };
   template <> struct GetElementTypeById<Element::Id::MkSeekHead> { using type = MkSeekHead; };
   template <> struct GetElementTypeById<Element::Id::VoidElement> { using type = VoidElement; };

taglib/matroska/ebml/ebmlmkinfo.cpp

@@ -38,6 +38,7 @@ void EBML::MkInfo::parse(Matroska::Properties *properties)
 
   unsigned long long timestampScale = 1000000;
   double duration = 0.0;
+  String title;
   for(const auto &element : elements) {
     Id id = element->getId();
     if (id == Id::MkTimestampScale) {
@@ -46,8 +47,12 @@ void EBML::MkInfo::parse(Matroska::Properties *properties)
     else if (id == Id::MkDuration) {
       duration = element_cast<Id::MkDuration>(element)->getValueAsDouble();
     }
+    else if (id == Id::MkTitle) {
+      title = element_cast<Id::MkTitle>(element)->getValue();
+    }
   }
 
   properties->setLengthInMilliseconds(
     static_cast<int>(duration * static_cast<double>(timestampScale) / 1000000.0));
+  properties->setTitle(title);
 }

taglib/matroska/matroskafile.cpp

@@ -108,8 +108,12 @@ Tag *Matroska::File::tag() const
 
 Matroska::Tag *Matroska::File::tag(bool create) const
 {
-  if(!d->tag && create)
+  if(!d->tag && create) {
     d->tag = std::make_unique<Tag>();
+    if(d->properties) {
+      d->tag->setSegmentTitle(d->properties->title());
+    }
+  }
   return d->tag.get();
 }
 
@@ -305,6 +309,9 @@ void Matroska::File::read(bool readProperties, Properties::ReadStyle readStyle)
     d->properties = std::make_unique<Properties>(this);
     segment->parseInfo(d->properties.get());
     segment->parseTracks(d->properties.get());
+    if(d->tag) {
+      d->tag->setSegmentTitle(d->properties->title());
+    }
   }
 
   if(readStyle == AudioProperties::Accurate &&

taglib/matroska/matroskaproperties.cpp

@@ -40,6 +40,7 @@ class Matroska::Properties::PropertiesPrivate
 
   File *file;
   String codecName;
+  String title;
   int length { 0 };
   int bitrate { -1 };
   int sampleRate { 0 };
@@ -92,6 +93,11 @@ String Matroska::Properties::codecName() const
   return d->codecName;
 }
 
+String Matroska::Properties::title() const
+{
+  return d->title;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // private members
 ////////////////////////////////////////////////////////////////////////////////
@@ -125,3 +131,8 @@ void Matroska::Properties::setCodecName(const String &codecName)
 {
   d->codecName = codecName;
 }
+
+void Matroska::Properties::setTitle(const String& title)
+{
+  d->title = title;
+}

taglib/matroska/matroskaproperties.h

@@ -86,6 +86,13 @@ namespace TagLib::Matroska {
      */
     String codecName() const;
 
+    /*!
+     * Returns the general name of the segment.
+     * Some applications store the title of the file here, but players should
+     * prioritize the tag title over the segment title.
+     */
+    String title() const;
+
   private:
     class PropertiesPrivate;
     friend class EBML::MkInfo;
@@ -97,6 +104,7 @@ namespace TagLib::Matroska {
     void setChannels(int channels);
     void setBitsPerSample(int bitsPerSample);
     void setCodecName(const String &codecName);
+    void setTitle(const String &title);
 
     TAGLIB_MSVC_SUPPRESS_WARNING_NEEDS_TO_HAVE_DLL_INTERFACE
     std::unique_ptr<PropertiesPrivate> d;

taglib/matroska/matroskatag.cpp

@@ -74,6 +74,7 @@ class Matroska::Tag::TagPrivate
 
   SimpleTagsList tags;
   ByteVector data;
+  String segmentTitle;
 };
 
 Matroska::Tag::Tag() :
@@ -115,6 +116,11 @@ const Matroska::SimpleTagsList &Matroska::Tag::simpleTagsList() const
   return d->tags;
 }
 
+void Matroska::Tag::setSegmentTitle(const String& title)
+{
+  d->segmentTitle = title;
+}
+
 void Matroska::Tag::setTitle(const String &s)
 {
   d->setTag("TITLE", s);
@@ -152,7 +158,11 @@ void Matroska::Tag::setTrack(unsigned int i)
 
 String Matroska::Tag::title() const
 {
-  return d->getTag("TITLE");
+  String s = d->getTag("TITLE");
+  if(s.isEmpty()) {
+    return d->segmentTitle;
+  }
+  return s;
 }
 
 String Matroska::Tag::artist() const

taglib/matroska/matroskatag.h

@@ -98,6 +98,8 @@ namespace TagLib {
       friend class EBML::MkTags;
       class TagPrivate;
 
+      void setSegmentTitle(const String &title);
+
       // private Element implementation
       ByteVector renderInternal() override;