[MPlayer-users] Strange problem with videos having mixed stereo and 5.1 sound - slow playback

[Carl Eugen Hoyos]

Reimar Döffinger <Reimar.Doeffinger <at> gmx.de> writes:

> On Wed, Jul 14, 2010 at 06:22:18PM +0000, Carl Eugen Hoyos wrote:
> > Florian Schröck <floschroeck <at> googlemail.com> writes:
> > 
> > > Some MKV files, which have been recorded from an HDTV broadcast TV
> > > shows, seem to have a AC3 audio track which is mixed stereo and 5.1. It
> > > is always the same issue: At the beginning of the file are scenes from
> > > the previous episode in stereo and right when the "real" episode begins,
> > > the sound switches to 5.1 and the playback gets really slow, like slow
> > > motion, the picture and the audio, too.
> > 
> > The problem is known
> 
> Not to me. I'd expect the channel change is not detected and/or the filter
> chain not proper reinitialized.

It is a kind of regression, since it's not reproducible with liba52 (but with
old mplayer and -ac ffac3).

I uploaded ac3channelchange.ts to incoming, note the difference in A-V and ct.
(-demuxer lavf -aid 1 shows the same symptoms)

Carl Eugen

$ mplayer ac3channelchange.ts -endpos 62663 -channels 2
MPlayer SVN-r31735-4.4 (C) 2000-2010 MPlayer Team

Playing ac3channelchange.ts.
TS file format detected.
VIDEO H264(pid=1920) AUDIO A52(pid=1923) NO SUBS (yet)!  PROGRAM N. 1000
FPS seems to be: 50.000000
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
==========================================================================
==========================================================================
Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders
AUDIO: 48000 Hz, 2 ch, s16le, 448.0 kbit/29.17% (ratio: 56000->192000)
Selected audio codec: [ffac3] afm: ffmpeg (FFmpeg AC-3)
==========================================================================
AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
Starting playback...
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
VO: [vdpau] 1280x720 => 1280x720 Planar YV12
A:62663.0 V:62663.1 A-V: -0.042 ct: -1.140 558/558 35%  8%  0.7% 1 0

$ mplayer ac3channelchange.ts -endpos 62663 -channels 6
MPlayer SVN-r31735-4.4 (C) 2000-2010 MPlayer Team

Playing ac3channelchange.ts.
TS file format detected.
VIDEO H264(pid=1920) AUDIO A52(pid=1923) NO SUBS (yet)!  PROGRAM N. 1000
FPS seems to be: 50.000000
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
==========================================================================
==========================================================================
Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders
AUDIO: 48000 Hz, 2 ch, s16le, 448.0 kbit/29.17% (ratio: 56000->192000)
Selected audio codec: [ffac3] afm: ffmpeg (FFmpeg AC-3)
==========================================================================
AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
Starting playback...
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
VO: [vdpau] 1280x720 => 1280x720 Planar YV12
A:62662.6 V:62663.1 A-V: -0.453 ct:-11.522 558/558 34%  7%  0.8% 1 0