[MPlayer-dev-eng] mplayer A/V sync: in sync when fed to stdin, out of sync when reading file directly?

[William R Sowerbutts]

I have recorded some DVB-t video to disk. I record UK DVB-t broadcasts using a
PCI Nova-T card and using some software I've written. It converts the audio
and video stream from the TS into a single PES and records that to disk using
code from the ts2ps app from mpegtools. I can provide a sample MPEG file which
exhibits this problem if anyone wants to see one.

I am using mplayer cvs from 2003-01-06. My audio hardware is an M-Audio
Dio2496 card using ALSA 0.9.0rc5 drivers with OSS compatability via the
mplayer SDL output plugin. My video hardware is a Matrox G550 card using the
mga_vid driver from mplayer cvs. I run mplayer from a 1024x768 framebuffered
console.

If I play the file with mplayer by providing the filename on the command line
then the audio and video appear out of sync by a constant amount:

$ mplayer -cache 4096 -ao sdl -vo mga ./video.mpg          # a/v out of sync

I can correct this by adding a parameter of "-delay -0.15" (-0.15 feels about
right but not quite right).

However, if I play the video via stdin, the A/V sync is absolutely spot on:

$ mplayer -cache 4096 -ao sdl -vo mga - < video.mpg        # a/v is in sync

Is this a bug? Or am I missing some vital point? Perhaps mplayer ignores the
PTS timestamps unless it is streaming the video via stdin?

Thanks,

Will

_________________________________________________________________________
William R Sowerbutts                                  will at sowerbutts.com
Coder / Guru / Nrrrd                                http://sowerbutts.com
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