[mythtv-users] ALSA and Digital Output

Nick knowledgejunkie at gmail.com
Fri Apr 29 00:24:34 UTC 2005


On 4/28/05, Meyland Peter <PME at vestamt.dk> wrote:
>  
> 
> Hellow List 
> 
> Can anyone here help me to get S/P DIF to working on ASUS P4R800V Deluxe so
> all sound goes throug the digital output? 
> 
> Output from aplay - l: 
> **** List of PLAYBACK Hardware Devices **** 
> card 0: IXP [ATI IXP], device 0: ATI IXP AC97 [ATI IXP AC97] 
>   Subdevices: 1/1 
>   Subdevice #0: subdevice #0 
> card 0: IXP [ATI IXP], device 1: ATI IXP IEC958 [ATI IXP IEC958 (AC97)] 
>   Subdevices: 1/1 
>   Subdevice #0: subdevice #0 
> 
> I hope somone can help me 

Hi Peter,

I am running an Asus Pundit-R which also uses the ATI IXP chipset for
audio. This runs fine using ALSA 1.0.8 (I downloaded and compiled mine
a while back) I see you are using atrpms packages for yours so you
should be fine.

In order to route *all* sound through the SPDIF you need to set up
your ~/.asoundrc file to direct all PCM output to your SPDIF and not
your regular line-out. On the ATI IXP, the line-out should be device 0
on the card, and the SPDIF device 1.

Therefore, your ~/asoundrc file should look like this:

#------------------- start cut here ----------------------
pcm.atiixp {
type hw
card 0
}

ctl.atiixp {
type hw
card 0
}

pcm.!default {
type hw
card 0
# device 0    ## uncomment this line for analog line-out
device 1    ## uncomment this line for SPDIF out
}
#-------------------- end cut here ----------------------


This allows you to uncomment either device #0 (for analog output) or
device #1 (SPDIF, which is what you want) which sets this as the
default device for all sound output.

Using alsamixer, you will also need to change a couple of IEC958 based
settings. To enable SPDIF output, I had to:

set IEC958 Playback Switch to TRUE (turn it on)
set IEC958 Playback AC97-SPSA to 3

Once this is done and it is working, I'd recommend storing this setup
to a state file, so that you can restore this easily in the future:

alsactl -f /etc/asound.state.spdif store

In MythTV, use ALSA:default for sound output.

There are issues if you are using a PVR-350 card and running its
decoded audio back into your soundcard and then out of the SPDIF, but
all normal audio (live TV, recordings, music etc) should be fine.

Let us know how it goes,

Nick


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