[MPlayer-dev-eng] [BUG] [PATCH] Ogg/Theora frametime broken on 0-length packets

[David Kuehling]

Hi,

I noticed that a/v sync drifts in theora files that contain 0-length
video demux packets (i.e. frames where the image doesn't change at all),
when played back with -demuxer ogg.  The libavformat demuxer seems to
work correctly.  However it uses so much memory (a leak), that it won't
work on the target platform (NanoNote: 32MB RAM, no swap).

Looking closer, I found that ds_get_next_pts() returns the *current* pts
when the packet read last has zero length.  This is due to the check
for 'ds->buffer_pos' to see whether data have already been read from the
*current* packet.  Of course, ds->buffer_pos will stay when a
zero-length packet was read, so that fails.

The atteched patch fixes that by skipping the frametime computation that
involves ds_get_next_pts(), thus just using the stream's frametime from
sh_video.  (Ogg/Theora is strictly constant-framerate, so there is no
reason to do the complex per-frame frametime computation anyway).

cheers,

David
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