[mythtv-users] Audiophile and TV audio?

Alen Edwards allen.edwards at oldpaloalto.com
Mon Jun 23 19:31:58 UTC 2008

Joe Henley wrote:
> Allen,
> When you say "SPDIF for my surround processor" I assume you mean you 
> want to output a signal from your sound card SPDIF connector into a 
> receiver/amp which will convert the digital signal from the SPDIF into 
> analog and then output that thru your speakers. Ie., the digital to 
> analog takes place in the receiver/amp.
> If so, then from my experience, I'd recommend you use alsa drivers to 
> send the signal thru the SPDIF.  STAY AWAY from PukeAudio, it is still 
> far too buggy to use in complex environments.  With a receiver/amp to do 
> your digital to analog conversions, you don't need to care about alsa's 
> up-conversion capabilities.
> As for drivers for your sound card, it's one I'm unfamiliar with.  You 
> would probably do best by googling the primary dsp chip for info.  There 
> are fewer of those than you might imagine, so many folks have luck with 
> drivers for other card brands, but same dsp.  In my case, I found the 
> alsa and alsa wiki sites helpful.
> On the less positive side, if I recall correctly, there aren't many 
> folks who have had success getting simultaneous output of SPDIF and 
> analog (some output jack on the sound card).  You would probably have 
> more success getting SPDIF to your reveiver/amp to work, then grab the 
> additional analog you want from an auxillary output on the receiver/amp.
> Good luck!  It's possible to do what you want with enough time, energy, 
> and money.  ;-)
> Joe Henley
> ______________
Hi Joe,

Thanks for the reply.  I actually have s/pdif and analog R+L working 
fine, just not at the same time.

I concluded that ALSA and Pulseaudio would not work, which is why I was 
looking for help getting into the driver, which must be part of 
Mythbuntu or more likely Ubuntu.  I say this because I don't want the 
computer doing any decoding as my decoder is high end and does some nice 
things like move base around depending on speaker crossovers.

What I am doing now is using S/PDIF passthrough output to TWO external 
sound decoders, one 5.1 and one 2.0 (for the TV).  I have not actually 
hooked both up physically, but I am sure it can be done either with a 
splitter or with the second spdif output on the MB.

This is not very elegant which is why I wanted help finding something 
about the driver.  The HDA spec is too low a level, there is a linux 
ALC883 driver but without any documentation, and the ASUS has no Linux 
driver for the M3A.  For those reasons, I conclude that the driver must 
be in the Ubuntu distribution as I didn't load anything special.

I know that a HDA chip can do but I may need to modify the driver.

Thanks again for the reply,


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