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Re: Simultaneous AC3/DTS passthrough & stereo analog output



Andrew Sackville-West wrote:
On Tue, Oct 09, 2007 at 09:39:41AM +0100, Bob wrote:
Bob wrote:
I'm using an Audigy2 in one PC and an SB Live value in another and I output to a 5.1 speaker system over S/PDIF coax and to my headphones (via the TV) over analogue stereo.

I have AC3 passthrough working when I call mplayer with -afm hwac3, (I think DTS will work but can't find a test clip) and I can soft decode and downmix the AC3 audio with -afm liba52, so that's all great, except that with -afm liba52 rear left and right are mixed and I don't get anything out of the LFE track.

What I can't do is both at once which would make life easer for SWMBO.

I haven't followed this thread and frankly have not much idea what
you're talking about here, but maybe pulseaudio can do what you need?
just a thought.

Thanks for your suggestion, on investigation it appears that PulseAudio cannot do AC3 pass through, I may be able to get it to work by having mplayer output 6 channel PCM, splitting it, downmixing one stream to stereo and outputting it to the analog output and using a real time software AC3 encoder to re-encode the second stream then outputting that to S/PDIF.

There would be quite a quality/performance penalty though, particularly at low volume.

I'd like to output the raw unadulterated AC3 / DTS as it came of the DVD to S/PDIF and a downmixed stereo version to analog.

I've been fruitlessly searching the MythTV mailing list as this crops up fairly regularly over there.

Oh well, guess it's not possible, it's funny, usually a product implemented in software gives you more flexibility than a dedicated hardware version but my cheep consumer DVD player automatically does this.

Thank you for you time.



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