[linux-audio-user] USB Audio has played but no longer does so.

[Martin Habets]

Chris Lyon wrote:
>I'm sorry that I've obviously phrased this question all wrong.
>so I'll try to be a little bit more detailed this time.
>
>I have now installed Mandrake 10.1 on the machine.
>and now aplay -l does indeed report the existance of UA-100 card
>kscd shows all the typical signs of  playing a cd, it lists tracks, it 
>starts counting when play is pressed,
>But no sound emerges.
>amixer reports no mixer elements, or nothing.
>
>/proc/asound/cards displays an endless stream of
>0 [UA100       ]: USB-Audio - UA - 100
>                         Roland UA - 100 at usb-0000:00:07.2 - 2, full 
>speed

I don't know what kernel version you're on, but there is a bug in procfs
in 2.6.8 that causes a cat of any file in /proc to loop endelessly.

>if I try to select a Device with
>aplay -D= *****
>nothing I type in seems to make any sense to it.
>if I try to list pcm devices to plug into the above line with aplay -D 
>the results are to say the least incomprehensable.

With only one card you should no longer need to specify -D any more.
But normally "-D hw:0,0,0" should work if you have 
/proc/asound/card0/pcm0p/sub0.

>Where do I go next?  This used to work when I installed 9.2 originally 
>but I have been poking & proding for 4 days now and It still desn't 
>work. ONce again I apologies for the way I present my questions but I am 
>NOT pestering before trying, I am on a last ditch attempt to play a CD 
>on a linux box.
>I won't bore you with my background, but I have a little involvement in 
>the synth, computing and audio field and yet this is now getting way 
>beyond a joke.  I have had this playing with Micheal Minns MMUSAUDIO . 
>However ALSA seems the way to go for all things Audio and Linux.
>So how do you check the signal path in a system? and what do you do if a 
>device appears not to be supported by the mixing facilities?

- If you cat /proc/asound/devices you should see a ctl and playback
device with "[0-..." in the line (0 is your card number I think).
- cat /proc/bus/usb/devices, look at the interfaces (I:) provided on you USB
device. And check if the interfaces have a "Driver=" entry.

My 2 cents,
Martin