Fwd: Simultaneous AC3/DTS passthrough & stereo analog output
I saw this on a Debian mailing list and maybe you may help:
---------- Forwarded message ----------
From: Bob <spam@homeurl.co.uk>
Date: Oct 11, 2007 5:15 AM
Subject: Re: Simultaneous AC3/DTS passthrough & stereo analog output
To: debian-user@lists.debian.org
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.
--
my place on the web:
floss-and-misc.blogspot.com
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