On Sat, May 30, 2009 at 2:36 AM, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:
> It helps if you give information about the sound card, not about yourself.
It's not a sound "card". It's a little external box connected by USB.
When I plug it in, it is recognised by the USB layer and installs the
snd-usb-audio module:
May 30 10:30:20 proton kernel: usb 4-1: new full speed USB device
using uhci_hcd and address 2
May 30 10:30:20 proton kernel: usb 4-1: configuration #1 chosen from 1 choice
May 30 10:30:20 proton kernel: usb 4-1: New USB device found,
idVendor=0763, idProduct=2010
May 30 10:30:20 proton kernel: usb 4-1: New USB device strings: Mfr=1,
Product=2, SerialNumber=0
May 30 10:30:20 proton kernel: usb 4-1: Product: Fast Track
May 30 10:30:20 proton kernel: usb 4-1: Manufacturer: M-Audio
May 30 10:30:21 proton kernel: usbcore: registered new interface
driver snd-usb-audio
Also a new device is added:
# cat /proc/asound/cards
0 [Intel ]: HDA-Intel - HDA Intel
HDA Intel at 0xfe020000 irq 17
1 [Track ]: USB-Audio - Fast Track
M-Audio Fast Track at usb-0000:00:1a.1-1, full speed
However, amixer does not change:
# amixer info
Card default 'pulse'/'PulseAudio'
Mixer name : 'PulseAudio'
Components : ''
Controls : 4
Simple ctrls : 2
Clearly this is because the PulseAudio server is in the way.
If I go to the GNOME desktop menu System > Preferences > Hardware >
Sound I now see "USB Audio" under Audio Conferencing : Sound capture
and under Default Mixer Tracks I see an additional 4 entries that
reference "USB Audio" and "Fast Track (Alsa mixer)".
My ALSA packages seem to have version number 1.0.17.
> The documentation is primarily in the code. One of Alsa's weak points has
> always been documentation. But is it documentation you want or do you want
> your card to work?
When I described myself I was informing the list that I am capable of
diagnosing and fixing complex linux issues because I am a seasoned
programmer and have scientific discipline. However, due to the fact
that the sound system on Linux transcends the kernel, user space and
desktop sound server, I am completely at a loss as to where to even
begin.
I first need to identify the component that may be responsible for
getting capture to work on the Fast Track USB (not "pro" or "ultra").
Is there no document that describes how ALSA interfaces with the
capture capability of a device?
Is there a way to debug ALSA so that it will record more information
somewhere that might identify the component(s) responsible.
What is the communications protocol used over USB to send commands to
this device?
Mike
>> Ultimately I want to test and characterize small audio circuits and
>> right now I have only a mic level input. I happen to have this M-Audio
>> thing so I was hoping to get a really good high sample rate, high
>> impedance, low noise from it.
>>
>> Mike
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