[FFmpeg-devel] [PATCH] mpegts: Write subtitle extradata if set

[Tomas Härdin]

Hi

When remuxing mpegts with dvbsub streams no subtitles are output when
ffplay or vlc decodes the resulting file. I've tracked this down to two
causes:

1. The mpegts muxer doesn't write the subtitle stream's extradata
(compare mpegts.c:987 and mpegtsenc.c:279). Instead it makes up its own
data, which then causes the dvbsub decoder to do nothing since page_id
matches neither composition_id nor ancillary_id

2. dvbsub_parser strips a few bytes off the subtitle data. These bytes
need to be put back in before the packets are muxed, presumably using a
bitstream filter

I thought I'd post the first fix on that list while I work on the second
part. The fix is simple: if the muxer has exactly 4 B extradata for the
subtitle stream then write it.

Patch attached, passed regtests. Also attached indentation patch. I
could upload a sample if you wish. I didn't yet because the patch is
quite trivial.

/Tomas
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