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Jooon
13th April 2005, 01:17
From the audio FAQ (http://forum.doom9.org/showthread.php?s=&threadid=68300#post424391):
12. Is it possible to pass AAC over S/PDIF?

It is possible, although it has not yet been fully implemented. Only a few hardware devices currently support AAC decoding, and no DirectShow filter has yet been implemented with AAC pass-through ability. However, this is definitely a possibility for the future. Read more about S/PDIF and AAC hardware support here and here.

However, until AAC over SPDIF becomes more viable, there are several DirectShow filters that can be used to encode six channel AAC to AC3 over S/PDIF on the fly. Dolby Out DS filter by Haaan , as well as 1.x versions of AC3Filter can be used for this purpose. Although this reencoding on the fly process will theoretically result in a quality loss, using the full 640 kb/s bitrate allowed will result in an excellent listening experience and minimal quality loss.

Is there a way to do this in Linux? As far as I know, mplayer can't natively output the audio it has decoded as ac3. However, is it possible to somehow pipe the audio through ffmpeg's ac3 encoder or something similar? Or is there any other programs that can handle it?

KpeX
13th April 2005, 16:37
I don't know of any way to encode to AC3 on the fly right now in linux. Mplayer could be fairly easily extended to do this, I think.

The only possibility that comes to mind with current tools would be using gstreamer ( faad ! ffenc_ac3 ! alsasink ) but when I attempted such a pipeline gstreamer crashed.