[mythtv-users] mythmusic iec958 help

[Joe Henley]

Gregg,

I assume (from the alsa file names) you're running Fedora Core 8.  If 
that's correct, then the first couple of "Info" boxes on the wiki you 
reference are saying to NOT use a modified .asoundrc file.  So go back 
to the original from the FC8 distribution.

Also, are you using PukeAudio?  If so, gert rid of it.  It's still too 
"bleeding edge" to use.  (There are _lots_ of notes around about how to 
do that.)

 From your note, it sounds like you want to take the CDRom info, output 
it thru the SPDIF connector to a separate amp/receiver/home theater 
receiver/etc.  If that's correct, then you want alsa plus the sound card 
  to do nothing to the signal; only stuff it into the SPDIF connector. 
You want your receiver to decode and then push it to the speakers.

Most receivers these days, if they can handle (digital) SPDIF at all, 
can figure out the underlying sample frequency (44.1KHz or 48 KHz), and 
decode it correctly.  The problem often comes when the sound card gets 
in the middle and insists on re-coding the CDRom (native) signal as 
being 48 KHz.  The result is that the sound is then shifted upward in 
frequency about 10% when the receiver decodes it.

Now the bad news.  IIRC, most soundblaster cards cannot output a 44.1KHz 
signal.  So they code everything as 48KHz.  I don't like Creative stuff 
so I'm not familiar with the specifics of their cards these days.  You 
should be able to google "Soundblaster Live 5.1" and "bit perfect audio" 
and get some useful info on your card's output capabilities.  I fear you 
may be in the market soon for a replacement card.

I had a similar problem awhile back and ended up getting a Turtle Beach 
Riviera card.  It was 20 or 30 bucks and "just works" in Linux.

Once you go back to the original .asoundrc file, get rid of PukeAudio, 
get a soundcard which can output a proper 44.1KHz signal on the SPDIF 
connector (or hopefully find a setting on SB Live card if possible), 
then your MythTV settings above should be OK.

Good luck and come back here if you have questions.

Joe Henley