[MPlayer-dev-eng] MPEG-TS demux problem?

Zoltan Hidvegi mplayer at hzoli.2y.net
Fri Jul 22 07:06:21 CEST 2005


Nico Sabbi wrote:
> I found this: starting from the beginning of the dumped audio file
> the first frame has flag 0xa (stereo | channel1) the others are plain 
> stereo.
> Maybe liba52 fails to reinit correctly

I was looking at that before, but that does not seem to be a problem.
a52_frame is called every time in decode_audio, which reparses the
frame header.  There is no permanent state.  The audio init sets the
downmix target, the default is 2 channels, and liba52 will downmix
anything to 2 channels, and the downmixer is initialized every time
a52_frame is called, so it can accomodate changing channels in the
source.  The output of liba52 will always be the downmixed 2-channel
audio, which does not change.  And keep in mind the hwac3 has the same
problem, and the same jibberish comes out of my Dolby Digital
receiver.  It is possible that the sample I've uploaded just does not
have any meaningful audio, but I think I've seen this happen in a good
file, which plays without problem sequentially, but if you seek, it
can get into this jibberish state.  But I am no longer certain that
I've really seen such a case.  This particular sample is from a
program/ad boundary, where they do switch streams, maybe it's messed
up.  But mplayer should be able to recover, but instead the A/V desync
gets too big, and the audio is disabled.  Seeking forward/back will
re-enable the audio, and with some luck, you'll seek back to a place
where the audio is OK.

Zoli




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