[FFmpeg-devel] [PATCH] Add matroska codec id S_TEXT/WEBVTT for WebVTT streams.

[Walter Wong]

Added the codec id S_TEXT/WEBVTT in order to bring ffmpeg generated files
closer to the matroska spec. The list of matroska codec ids was also
rearranged to push the old codec id (D_WEBVTT/SUBTITLES) to the bottom of
the list so that S_TEXT/WEBVTT is the default codec id for new mkv files
with webvtt subtitles.

Fixes ticket #5641: http://trac.ffmpeg.org/ticket/5641
---
 libavformat/matroska.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/libavformat/matroska.c b/libavformat/matroska.c
index 7c56aba403..1128c96451 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},
@@ -100,6 +96,14 @@ const CodecTags ff_mkv_codec_tags[]={
     {"V_VP8"            , AV_CODEC_ID_VP8},
     {"V_VP9"            , AV_CODEC_ID_VP9},
 
+    /* These codec strings for webvtt seem to be depreciated from the Matroska
+       spec, but it might be useful to keep them for compatibility for older
+       files. These are at the bottom so they get matched after S_TEXT/WEBVTT. */
+    {"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},
+
     {""                 , AV_CODEC_ID_NONE}
 };
 
-- 
2.30.0