[mythtv-users] asoundrc and 5.1

[Al McIntosh]

Lachlan McIntosh wrote:
> Hi Al
>
> I have a similar hardware setup.
>
> Your /etc/asound.conf and ~/.asoundrc will need to be set up like:
>
> pcm.!default {
> type plug
> slave {
> pcm "spdif"
> rate 48000
> format S16_LE
> }
> }
>   

Lachlan, are your TV recordings HD or Analogue? My analogue recordings 
only produce sound in the front L,R and center channels. I may tinker a 
bit with the above ~/.asoundrc  to see if I can make it work.

> And you will need to use the device ALSA:default (otherwise it seems
> that you can't use pass-through AC3 and PCM)
>
> If you connect speakers to your sound card using a digital cable
> (RCA/SPDIF or optical) then the software speaker test will only output
> from two speakers.
>
> I personally use "speaker-test -Dplug:spdif -c7 -t2 -f100" but only get
> front left and front right.
>
> The reason for this is that the speaker test signal is not in AC3 nor
> DTS format.
>
>   
I realized this soon after sending my origional email, I noticed my 
receiver displayed "PCM 48000" everytime speaker-test sent pink noise 
destined for the front R&L channels.  :$


> If anyone knows how to make it do AC3 or DTS then please let us all know
> :o)
>
> Oh also it helps to make sure that if you don't have the correct cable
> that you use at least a STEREO 3.5mm to RCA lead for the spdif from your
> sound card as I once spent a hour trying to figure out why my sound was
> intermittent.
>
>   

I have the following card,
http://upload.wikimedia.org/wikipedia/commons/thumb/d/d0/Sound_Blaster_Live!_5.1.jpg/200px-Sound_Blaster_Live!_5.1.jpg

I plugged this adaptor into the yellow "digital out" jack on the card,
http://allanmcintosh.com/pics/tmp/stereo-mini_to_coaxial.jpg

Then a 75 OHM digital RCA cable into the adaptor and the other end to 
the DVD input of my reciever.

I have this set up now working, using the following ~/.asoundrc, I was 
unable to use your, Lachlan's, example, it did not report any errors, it 
simply didn't produce any sound. Interestingly, using `speaker-test` and 
`mplayer -ao alsa:device=digital -afm hwac3 dvd://` as diagnostic tools 
were horribly misleading. DVDs  played using mythtv Internal DVD player 
worked well with DTS enabled using
ALSA:default. Recorded playback works but only in the front channels.
 

pcm.!default {
  type plug
  slave.pcm "digital-hw"
}
ctl.!default {
  type hw
  card Live
}
pcm.digital {
  type plug
  slave.pcm "digital-hw"
}
ctl.digital {
  type hw
  card Live
}
pcm.digital-hw {
  type hw
  card Live
  device 2
}

ctl.digital-hw {
  type hw
  card Live
}