[mythtv-users] Does SPDIF Input generally work?

[Ken Scales]

Mitch Gore wrote:
> On 8/29/07, *Bearcat M. Sandor* <HomeTheater at feline-soul.com 
> <mailto:HomeTheater at feline-soul.com>> wrote:
>
>     Folks,
>
>     I've been looking all over the wiki for this one and i can't find it.
>     Provided that i get a sound card that is well supported, will
>     MythTV record
>     tv audio  using the spdif input?   Can i expect any problems with
>     this? It
>     appears to be just fine, but i'm about to make a purchase of an
>     m-audio usb
>     soundcard and it only has spdif in.
>
>     Thank you,
>
>     Bearcat M. Sandor
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>
>
>
>
> i would assume it would work but i have to ask what are you recording 
> that has digital sound and the sound isn't built into the steam as in 
> HDTV recorded via firewire or QAM or antenna.
>
> Mitchell
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>   

I'm not the OP, but one example: my ExpressVu PVR5100 ( = Echostar 
PVR501) records the AC3 soundtrack when transmitted, and plays back with 
s-video and spdif (as well as analogue sound of course).  My older 4700 
receiver also has spdif output.  I'd like to try capturing the spdif and 
mplex-ing it with my video recordings, like Bearcat is proposing, so 
that I could put them onto my much larger Myth storage without losing 
the DD surround. (Aside: yes, I'm familiar with "PVRexplorer", but I'm 
not running Mac or Windows right now.)

I expect some sync issues, but as long as both "tracks" are stable 
timewise (granted, a big hope), adjusting for a time-delay between them 
can be done with available tools (probably manually at first).

So, to echo Bearcat's request, is there a recommended way of setting up 
and capturing spdif audio? (Even something as crude as "cat < /dev/dsp2 
 > filename.ac3" -- to start exploring the possibilities of doing this.) 
It could be an interesting project to work on over the winter months...

Ken.