[LAU] M-Audio Fast Track Pro: unreliable, distorted recording

[Lewis Pike]

Hi Guillaume,

On Tue, Feb 04, 2014 at 06:29:28PM +0100, Guillaume Pellerin wrote:
> Sorry Lewis, I was AFK these days. Back now :)
> 
> Can you try to add this line to /etc/modprobe.d/alsa-base.conf
> 
> options snd_usb_audio vid=0x763 pid=0x2012 device_setup=0x03 enable=1 nrpacks=1
> 
> and then:
> $ sudo modprobe -r snd-usb-audio
> $ sudo modprobe snd-usb-audio

I added your suggested kernel module option line and rebooted my
system for good measure.

$ cat /proc/asound/card0/stream0 # now gives:
M-Audio FastTrack Pro at usb-0000:00:1d.0-2, full speed : USB Audio

Playback:
  Status: Stop
  Interface 2
    Altset 2
    Format: S24_3BE
    Channels: 2
    Endpoint: 3 OUT (ADAPTIVE)
    Rates: 44100, 48000
  Interface 2
    Altset 5
    Format: S24_3BE
    Channels: 2
    Endpoint: 3 OUT (ADAPTIVE)
    Rates: 8000 - 48000 (continuous)

$ cat /proc/asound/card0/stream1 # now gives:
M-Audio FastTrack Pro at usb-0000:00:1d.0-2, full speed : USB Audio #1

Playback:
  Status: Stop
  Interface 3
    Altset 2
    Format: S24_3BE
    Channels: 2
    Endpoint: 4 OUT (ADAPTIVE)
    Rates: 44100, 48000
  Interface 3
    Altset 5
    Format: S24_3BE
    Channels: 2
    Endpoint: 4 OUT (ADAPTIVE)
    Rates: 8000 - 48000 (continuous)

Capture:
  Status: Stop
  Interface 4
    Altset 2
    Format: S24_3BE
    Channels: 2
    Endpoint: 5 IN (SYNC)
    Rates: 8000 - 48000 (continuous)

I've also updated my arecord test command to account for the the
S24_3BE format:

arecord -t raw -f S24_3BE -c2 -r 48000 -D hw:0,1 -vv | aplay -f S24_3BE -c2 -r 48000 -D hw:0,0

Unfortunately, I am still getting bad captures in about ~10% of my
test cases.  I have noticed a slightly different problem in this
configuration: about half of the bad captures are not just a distorted
signal, but instead very loud pure white noise.  My ears are still
ringing!

> un/replug the card and make your tests again.
> 
> I must admit I've almost always use the FTP with JACK so I'm not
> completly aware of the behavior of the device without it.
> 
> If this has no (good) effect, it could be something between you USB
> system and the kernel. I've discover recently that crackles could
> raise up on other cards and systems because of a dynamic USB ID
> allocation of the kernel. The pb disappeared when the option is
> switched off.
> 
> So, let's continue if the first ALSA tweak doesn't work..
> 
> Regards,
> Guillaume
> 

No luck so far, and the mystery continues.  Are there specific kernel
configuration options which you would advise disabling?  Here is a
snippet from my current /proc/config.gz which shows some settings
related to USB:

# --------------------------------------------
#
# Miscellaneous USB options
#
CONFIG_USB_DEFAULT_PERSIST=y
CONFIG_USB_DYNAMIC_MINORS=y
# CONFIG_USB_OTG is not set
CONFIG_USB_MON=m
CONFIG_USB_WUSB=m
CONFIG_USB_WUSB_CBAF=m
# CONFIG_USB_WUSB_CBAF_DEBUG is not set
# --------------------------------------------

Again, your help on this one is much appreciated!

.lewis