[MPlayer-dev-eng] AAC decoding is out of sync

Dan Oscarsson Dan.Oscarsson at tieto.com
Thu Apr 15 18:50:57 CEST 2010


Upgrading from the source snapshop of 2010-03-06 to current shows that
changes have been done to AAC decoding and ffmpeg is tried before faad.

But now playing a DVB-T mpeg-ts stream with h.264 and AAC results in
audio being out of sync with video (status line says it is in sync but
you hear it is out of sync).

If I manually add -ac faad audio is in sync.

Also I not that if you seek in file when -ac faad is not used, A-V value
gets very much out of sync on status line, but not the audio.

So what is changed? It worked fine in the 2010-03-06 version.

Without -ac faad mplayer says:
==========================================================================
Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders
[aac @ 0xcab3a0]channel element 2.11 is not allocated
[aac @ 0xcab3a0]channel element 2.11 is not allocated
[aac @ 0xcab3a0]channel element 2.11 is not allocated
[aac @ 0xcab3a0]channel element 2.11 is not allocated
[aac @ 0xcab3a0]channel element 2.11 is not allocated
[aac @ 0xcab3a0]channel element 2.11 is not allocated
Unknown/missing audio format -> no sound
ADecoder init failed :(
Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)

Unsupported LATM configuration: 2 programs/ 42 subframes, 6 layers,
allstreams: 1

Unsupported LATM configuration: 5 programs/ 42 subframes, 6 layers,
allstreams: 1
FAAD: compressed input bitrate missing, assuming 128kbit/s!
AUDIO: 48000 Hz, 2 ch, s16le, 128.0 kbit/8.33% (ratio: 16000->192000)
Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio))
==========================================================================

With -ac faad I get:
==========================================================================
Forced audio codec: faad
Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)
FAAD: compressed input bitrate missing, assuming 128kbit/s!
AUDIO: 48000 Hz, 2 ch, s16le, 128.0 kbit/8.33% (ratio: 16000->192000)
Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio))
==========================================================================

What happens without -ac faad, does ffmpeg take over entire decoding?
I cannot see any big changes in the libmpdemux/libmpcodec directories so
I assume it has to do with ffmpeg.

The smallest sample I have where you can see a person talk and hear that
audio is out of sync is about 90 MB.

   Dan




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