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[SOLVED] playing MPEG4 5.1 sound "downsamples" to stereo
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VinzC
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PostPosted: Sun Oct 28, 2012 12:15 am    Post subject: [SOLVED] playing MPEG4 5.1 sound "downsamples" to Reply with quote

Hi all.

I have an MPEG4 movie that I'd like to play through my SPDIF output. So far, the movie has 6 channels. When I play it with mplayer, it says:
Code:
...
ID_AUDIO_FORMAT=MP4A
ID_AUDIO_BITRATE=447576
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=6
...
AUDIO: 48000 Hz, 6 ch, s16le, 447.6 kbit/9.71% (ratio: 55947->576000)
ID_AUDIO_BITRATE=447576
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=6
Selected audio codec : [ffaac] afm : ffmpeg (FFmpeg AAC (MPEG-2/MPEG-4 Audio))
==========================================================================
[AO_ALSA] Format floatle not supported by the hardware, trying default.
AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
ID_AUDIO_CODEC=ffaac

and the movie is played only in stereo, not AC3.

Can I tell mplayer to downsample floatle to something my hardware supports? (If that's how to call it.)

Thanks for any hint/suggestion.
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Last edited by VinzC on Wed Oct 31, 2012 8:47 pm; edited 2 times in total
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Navar
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PostPosted: Sun Oct 28, 2012 7:49 am    Post subject: Reply with quote

Did you try the -ac decode/filtering option? E.g., -ac hwac3, hwdts, a52.
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VinzC
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PostPosted: Mon Oct 29, 2012 5:54 pm    Post subject: Reply with quote

Navar wrote:
Did you try the -ac decode/filtering option? E.g., -ac hwac3, hwdts, a52.

I indeed tried hwac3 and hwdts, no sound.
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VinzC
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Location: Theux (Belgium)

PostPosted: Wed Oct 31, 2012 8:46 pm    Post subject: Reply with quote

Woohoo! Found an interesting forum post! Here's the command to resample AAC to AC3 on-the-fly
Code:
mplayer -af channels=6,lavcac3enc=1:448:3 movie.mp4

Now I get surround sound properly decoded to 5.1!
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