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

[Grozdan]

On Thu, Apr 15, 2010 at 6:50 PM, Dan Oscarsson <Dan.Oscarsson at tieto.com> wrote:
> 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

I think it was a bad call to add ffaac as default decoder for AAC as
it tends to screw up in a lot of cases. I prefer FAAD over it anytime.
You can add to mplayer.conf something like the below

ac=faad,

which will force FAAD decoding if it detects AAC audio in a file,
while falling back to appropriate decoder for all others. Make sure
you add the comma at the end :)

>
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