[mythtv-users] Installing an external USB sound device on Mythbuntu 10.10 [ADDENDUM]

Andrew C. Stadt acstadt at stadt.ca
Wed Mar 2 17:21:44 UTC 2011


On 02/03/2011 11:25 AM, Dave M G wrote:
> MythTV Users,
>
> I learned another important detail, so I thought I'd share it.
>
> Sometimes when I booted the computer, I was seeing an error that said:
>
> cannot find the slot for index 0
>
> When that happened, I had no sound. It happened randomly.
>
> After a little digging on the 'net, I discovered the problem was most
> likely with how I had set up my alsa-base.conf file.
>
> Long story short, I edited the alsa-base.conf file again:
>
> $ sudo gedit alsa-base.conf
>
> ... and I noticed that there was a section that said:
>
> # Prevent abnormal drivers from grabbing index 0
>
> ... and the card I wanted to load was listed in there. That seemed like
> an obvious contradiction, so I commented out the lines that applied to
> my preferred sound card, like so:
>
> # options snd-usb-audio index=-2
>
> (There were actually two of them in different places)
>
> Rebooted, and now my sound seems more stable.
>
> Hope that info is helpful to someone.
This seems be going a little OT for this list, and would probably be 
better handled by either the alsa (if that is you're preferred output 
path) or the mythbuntu lists/forums and as I haven't followed this whole 
thread (not being a Mythbuntu user myself), so this might have already 
been mentioned, but:

Rather then forcing the order of the module load (which is somewhat 
prone to failure) why don't you use alsa's builtin ability to force a 
'default' device:

For example, on one of my systems (not generally used for mythtv, but 
has a working frontend installed) with a usb audio headset plugged in, 
when I run aplay -L, I see:

mythtv at dogbert ~ $ aplay -L
null
     Discard all samples (playback) or generate zero samples (capture)
front:CARD=NVidia,DEV=0
     HDA NVidia, ALC662 rev1 Analog
     Front speakers
surround40:CARD=NVidia,DEV=0
     HDA NVidia, ALC662 rev1 Analog
     4.0 Surround output to Front and Rear speakers
surround41:CARD=NVidia,DEV=0
     HDA NVidia, ALC662 rev1 Analog
     4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=NVidia,DEV=0
     HDA NVidia, ALC662 rev1 Analog
     5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=NVidia,DEV=0
     HDA NVidia, ALC662 rev1 Analog
     5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=NVidia,DEV=0
     HDA NVidia, ALC662 rev1 Analog
     7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=NVidia,DEV=0
     HDA NVidia, ALC662 rev1 Digital
     IEC958 (S/PDIF) Digital Audio Output
hdmi:CARD=NVidia,DEV=0
     HDA NVidia, NVIDIA HDMI
     HDMI Audio Output
front:CARD=Headset,DEV=0
     Logitech USB Headset, USB Audio
     Front speakers
surround40:CARD=Headset,DEV=0
     Logitech USB Headset, USB Audio
     4.0 Surround output to Front and Rear speakers
surround41:CARD=Headset,DEV=0
     Logitech USB Headset, USB Audio
     4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Headset,DEV=0
     Logitech USB Headset, USB Audio
     5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Headset,DEV=0
     Logitech USB Headset, USB Audio
     5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Headset,DEV=0
     Logitech USB Headset, USB Audio
     7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=Headset,DEV=0
     Logitech USB Headset, USB Audio
     IEC958 (S/PDIF) Digital Audio Output

In this case, to make the usb default I could simply create a 
'/etc/asound.conf' with:

pcm.!default front:Headset

Please note I have no idea how this would work if you're using pulse 
and/or jack.

Of course I'm reasonably sure this makes this thread off topic for this 
list, as you've already found the preferred method of setting the audio 
output device for myth.


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