Gwyneth Morgan: > When writing WebMs, FFmpeg muxes WebVTT subtitles with the D_WEBVTT/* > codec tags from the WebM specs [1]. However, it does the same when > muxing MKV files, and the Matroska specifications instead use > S_TEXT/WEBVTT tags for WebVTT subtitles [2], which FFmpeg currently > doesn't understand. Support reading MKVs using either tag, write regular > MKVs with S_TEXT/WEBVTT, and write WebMs with the D_WEBVTT/* tags we > already use. > > [1]: https://www.webmproject.org/docs/container/ > [2]: https://matroska.org/technical/codec_specs.html#s_textwebvtt > > Signed-off-by: Gwyneth Morgan <gwy...@tilde.club> > Fixes: https://trac.ffmpeg.org/ticket/5641 > --- > v2: Rebase as later changes in ffmpeg.git conflicted with this patch. > > libavformat/matroska.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/libavformat/matroska.c b/libavformat/matroska.c > index 79b2d09..d9e5ff9 100644 > --- a/libavformat/matroska.c > +++ b/libavformat/matroska.c > @@ -60,16 +60,12 @@ const CodecTags ff_mkv_codec_tags[]={ > {"A_VORBIS" , AV_CODEC_ID_VORBIS}, > {"A_WAVPACK4" , AV_CODEC_ID_WAVPACK}, > > - {"D_WEBVTT/SUBTITLES" , AV_CODEC_ID_WEBVTT}, > - {"D_WEBVTT/CAPTIONS" , AV_CODEC_ID_WEBVTT}, > - {"D_WEBVTT/DESCRIPTIONS", AV_CODEC_ID_WEBVTT}, > - {"D_WEBVTT/METADATA" , AV_CODEC_ID_WEBVTT}, > - > {"S_TEXT/UTF8" , AV_CODEC_ID_SUBRIP}, > {"S_TEXT/UTF8" , AV_CODEC_ID_TEXT}, > {"S_TEXT/ASCII" , AV_CODEC_ID_TEXT}, > {"S_TEXT/ASS" , AV_CODEC_ID_ASS}, > {"S_TEXT/SSA" , AV_CODEC_ID_ASS}, > + {"S_TEXT/WEBVTT" , AV_CODEC_ID_WEBVTT}, > {"S_ASS" , AV_CODEC_ID_ASS}, > {"S_SSA" , AV_CODEC_ID_ASS}, > {"S_VOBSUB" , AV_CODEC_ID_DVD_SUBTITLE}, > @@ -78,6 +74,11 @@ const CodecTags ff_mkv_codec_tags[]={ > {"S_HDMV/TEXTST" , AV_CODEC_ID_HDMV_TEXT_SUBTITLE}, > {"S_ARIBSUB" , AV_CODEC_ID_ARIB_CAPTION}, > > + {"D_WEBVTT/SUBTITLES" , AV_CODEC_ID_WEBVTT}, > + {"D_WEBVTT/CAPTIONS" , AV_CODEC_ID_WEBVTT}, > + {"D_WEBVTT/DESCRIPTIONS", AV_CODEC_ID_WEBVTT}, > + {"D_WEBVTT/METADATA" , AV_CODEC_ID_WEBVTT}, > + > {"V_AV1" , AV_CODEC_ID_AV1}, > {"V_AVS2" , AV_CODEC_ID_AVS2}, > {"V_AVS3" , AV_CODEC_ID_AVS3},
The reason we write it the way we do is that webvtt is muxed differently in Matroska than WebM. This needs to be fixed, too, before S_TEXT/WEBVTT can be used for Matroska. - Andreas _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
