[MPlayer-users] AAC to AC3 to digital out on the fly on Mac OS X

[Mauro Bieg]

My goal is to play a multi-channel AAC file (as most trailers on apple.com/trailers are), convert it to AC3 on the fly and output it through the digital optical output of my MacBook Pro in order for the receiver to decode it. (the receiver can only handle AC3 Dolby Digital or DTS)

Right now my problem is even simple AC3 pass through. From http://www.avsforum.com/avs-vb/showthread.php?t=1024580 I got:
>>mplayer -channels 6 -ac hwac3 file.ac3

With the file from http://www.lynnepublishing.com/surround/www_lynnemusic_com_surround_test.ac3 (yes, 48kHz) the receiver doesn't recognize this as AC3, tries to play it back as PCM, the result being loud noise. 
The fun thing is that even mplayer seems to think of it as stereo:

Forced audio codec: hwac3
Opening audio decoder: [hwac3] AC3/DTS pass-through S/PDIF
No accelerated IMDCT transform found
hwac3: switched to AC3, 448000 bps, 48000 Hz
AUDIO: 48000 Hz, 2 ch, ac3, 448.0 kbit/29.17% (ratio: 56000->192000)
Selected audio codec: [hwac3] afm: hwac3 (AC3 through S/PDIF)
==========================================================================
AO: [macosx] 48000Hz 2ch ac3 (1 bytes per sample)

My mplayer build is from macports version 1.0rc2-4.0.1 and I'm on Mac OS X Leopard 10.5.5
Has anyone else got this to work on Leopard? Maybe with a self-compiled mplayer?



When I get simple AC3 passthrough to work, the next step would be to convert multi-channel AAC to AC3 on the fly. On this I found http://ubuntuforums.org/showthread.php?t=934833 but my mplayer doesn't have the lavc3enc audio filter (it doesn't show up in the list >>mplayer -af help). Does anyone know if this filter is available on Mac OS X, too?
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