#1924: ASS subtitles are demuxed inconsistently
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Reporter: gjdfgh | Type: defect
Status: new | Priority: normal
Component: avformat | Version: unspecified
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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There's a difference how subtitles are demuxed with the "matroska" and the
"ass" demuxers.
Consider an even like this in the source file:
{{{
Dialogue: 0,0:00:00.00,0:00:01.00,,,0000,0000,0000,,text
}}}
"matroska" outputs as packet:
{{{
0,0,,,0000,0000,0000,,text
}}}
while "ass" outputs:
{{{
Dialogue: 0,0:00:00.00,0:00:01.00,,,0000,0000,0000,,text
}}}
Matroska produces output that libass' ass_process_chunk() can consume.
That means an application using the ffmpeg demuxer interface to read ASS
subtitles (possibly for uniformity with the matroska case) has to add
extra workarounds. Further, the "ass" output doesn't include the event
index, while "matroska" does. (The event index is the first number, called
"ReadOrder" in libass.) Additionally, the "ass" output does not seem to
seem to set the packet duration correctly.
The "ass" decoder in libavcodec is indifferent to that, but libass can't
handle it. This makes the "ass" demuxer useless. Please fix.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1924>
FFmpeg <http://ffmpeg.org>
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