TX3G Subtitles not showing in Exoplayer #8271

Activity

1. AliZgheib

   added

   bug

   needs triage

   on Nov 23, 2020
2. icbaker

   self-assigned this

   on Nov 24, 2020
3. icbaker commented on Nov 24, 2020

   

   icbaker

   on Nov 24, 2020

   Collaborator

   More actions

   I looked at the file you provided in MP4Box.js.

   The trak box with id=5 (the tx3g one) has a hdlr box with handler=text. We treat this as a text track:
   

   ExoPlayer/library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

   Lines 794 to 795 in 59b34ed

   	} else if (hdlr == TYPE_text || hdlr == TYPE_sbtl || hdlr == TYPE_subt || hdlr == TYPE_clcp) {
   	return C.TRACK_TYPE_TEXT;

   However the stsd box contains a box with type=text. This isn't one of the subtitle types that we detect when parsing stsd boxes:
   

   ExoPlayer/library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

   Lines 892 to 896 in 59b34ed

   	} else if (childAtomType == Atom.TYPE_TTML || childAtomType == Atom.TYPE_tx3g
   	|| childAtomType == Atom.TYPE_wvtt || childAtomType == Atom.TYPE_stpp
   	|| childAtomType == Atom.TYPE_c608) {
   	parseTextSampleEntry(stsd, childAtomType, childStartPosition, childAtomSize, trackId,
   	language, out);

   I changed AtomParsers in two places: The if above to treat it as a text track and also inside parseTextSampleEntry() to assume text is tx3g:
   

   ExoPlayer/library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

   Line 928 in 59b34ed

   } else if (atomType == Atom.TYPE_tx3g) {

   Then the track appears in the track selector of the demo app, and renders "Chapter 1" semi-permanently (it eventually changes to "Chapter 2") - same behaviour as VLC.

   @kim-vde Do you know if a) type=text is valid for a stsd box? b) It's reasonable to assume this contains tx3g? Or is this media not quite structured correctly? (note I noted a different weirdness about this same media in #8260 (comment))
4. kim-vde commented on Dec 7, 2020

   

   kim-vde

   on Dec 7, 2020

   Contributor

   More actions

   I wouldn't add support for type text in ExoPlayer because this is the only issue reporting this (as far as I am aware of), I couldn't find anything about this type (in here for example) and because there is no apparent link between type text and tx3g.

   Do not hesitate to open another issue if you find information about this type (e.g. other issues, specifications).
5. kim-vde

   added

   bad media

   and removed

   bug

   needs triage

   on Dec 7, 2020
6. kim-vde

   closed this as completedon Dec 7, 2020
7. google

   locked and limited conversation to collaborators on Feb 6, 2021