[FFmpeg-devel] [PATCH] lavf/matroska: Handle ASS as ASS instead of SSA

[Clément Bœsch]

On Thu, May 01, 2014 at 01:45:58AM +0400, ValdikSS wrote:
> 
> 
> On 05/01/2014 01:24 AM, Clément Bœsch wrote:
> >On Thu, May 01, 2014 at 01:18:32AM +0400, ValdikSS wrote:
> >>On 05/01/2014 01:05 AM, Clément Bœsch wrote:
> >>>On Thu, May 01, 2014 at 12:56:23AM +0400, ValdikSS wrote:
> >>>>After introducing ASS codec id and renaming (old) ASS to SSA,
> >>>>Matroska ASS codec tag was mistakenly renamed too, making ASS
> >>>>subtitles handled as SSA.
> >>>>
> >>>>This fixes Ticket #3491
> >>>>---
> >>>>  libavformat/matroska.c | 4 ++--
> >>>>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>>>
> >>>>diff --git a/libavformat/matroska.c b/libavformat/matroska.c
> >>>>index e8e9996..7dc09b3 100644
> >>>>--- a/libavformat/matroska.c
> >>>>+++ b/libavformat/matroska.c
> >>>>@@ -67,9 +67,9 @@ const CodecTags ff_mkv_codec_tags[]={
> >>>>      {"S_TEXT/UTF8"      , AV_CODEC_ID_SRT},
> >>>>      {"S_TEXT/ASCII"     , AV_CODEC_ID_TEXT},
> >>>>  #if FF_API_ASS_SSA
> >>>>-    {"S_TEXT/ASS"       , AV_CODEC_ID_SSA},
> >>>>+    {"S_TEXT/ASS"       , AV_CODEC_ID_ASS},
> >>>>      {"S_TEXT/SSA"       , AV_CODEC_ID_SSA},
> >>>>-    {"S_ASS"            , AV_CODEC_ID_SSA},
> >>>>+    {"S_ASS"            , AV_CODEC_ID_ASS},
> >>>>      {"S_SSA"            , AV_CODEC_ID_SSA},
> >>>>  #endif
> >>>>      {"S_TEXT/ASS"       , AV_CODEC_ID_ASS},
> >>>
> >>>This was for compatibility, look below the #if/#endif. "SSA" packets were
> >>>still preferred, but maybe we can remove that ifdefery now.
> >>>
> >>>(Note that I didn't look at the ticket yet)
> >>As far as I understand, this #if/#endif block is used only if we use new
> >>API, which was introduced with the ASS/SSA split. If FF_API_ASS_SSA is not
> >>defined, we use old api with old ASS (and without SSA).
> >>
> >>If the old API is not used anymore, it might be better to always use
> >>#if/#endif block and remove the block below.
> >
> >See 7c1a002c
> >
> >tl;dr: AV_CODEC_ID_SSA is the old re-crafted hack format, AV_CODEC_ID_ASS
> >is the new verbatim data from mkv. Until the next bump (FF_API_ASS_SSA
> >ifdefery), we still continue to re-craft the packets because the
> >applications might be relying on that format instead. When we will bump,
> >the FF_API_ASS_SSA chunk will disappear and the verbatim format will be
> >choosen.
> 
> Thank you. It seems like I sent patch in haste.
> When the api bump will be? A lot of MKv files are muxed with ReadOrder and
> remuxing them breaks subtitles (see the ticket).

Last lavf major bump was in Feb 2013 (d8b31be6). I wouldn't mind bumping
right away, but that's a bit tricky because of politics & compat with
Libav.

-- 
Clément B.
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