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#1 2010-04-18 18:07:16

boomerang
Member
Registered: 2010-04-18
Posts: 10

[SOLVED] Audio dropouts with USB sound card

Hi! Recently I bought an external USB sound card (Music Fidelity V-DAC). If I plug in the USB cable the sound device is recognized by Phonon in KDE4 (kdemod).

If I play an audio file in Amarok (or VLC) the audio is indeed redirected to the USB sound card and played correctly. However, if I use my USB mouse, or USB keyboard dropouts are occurring in the audio signal. It seems that other USB devices are interfering with my USB sound card.

More details:
Arch Linux with kernel 2.6.33 and kdemod 4. Phonon backend is Xine. I also tried gstreamer, but this crashes Amarok/

$ cat /proc/asound/cards
 0 [Intel          ]: HDA-Intel - HDA Intel
                      HDA Intel at 0xfebfc000 irq 29
 1 [default        ]: USB-Audio - USB Audio DAC   
                      Burr-Brown from TI               USB Audio DAC    at usb-0000:00:1d.1-1, full s
$ dmesg | grep Audio
input: Burr-Brown from TI               USB Audio DAC    as /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.2/input/input12
generic-usb 0003:08BB:2706.0003: input,hidraw2: USB HID v1.00 Device [Burr-Brown from TI               USB Audio DAC   ] on usb-0000:00:1d.1-1/input2
input: Burr-Brown from TI               USB Audio DAC    as /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.2/input/input15
generic-usb 0003:08BB:2706.0005: input,hidraw2: USB HID v1.00 Device [Burr-Brown from TI               USB Audio DAC   ] on usb-0000:00:1d.1-1/input2

I also tried an Ubuntu (9.10) live CD. Using ALSA or Pulseaudio a clean audio signal without dropouts is produced.

I wonder if someone can help me with this problem, or point me to more information. Thanks!

Last edited by boomerang (2010-04-25 17:47:15)

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#2 2010-04-19 08:34:07

brebs
Member
Registered: 2007-04-03
Posts: 3,401

Re: [SOLVED] Audio dropouts with USB sound card

In /etc/modprobe.d/blah.conf I have:

options snd-hda-intel model=acer-aspire-8930g enable_msi=1 index=0

That "enable_msi=1" is important, so that "cat /proc/interrupts" shows hda_intel on its *own* interrupt. Hopefully that will stop the dropouts.

Last edited by brebs (2010-04-19 08:34:30)

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#3 2010-04-19 19:41:18

boomerang
Member
Registered: 2010-04-18
Posts: 10

Re: [SOLVED] Audio dropouts with USB sound card

Thanks for your suggestion. I added the following line to my /etc/modprobe.d/modprobe.conf file:

options snd-usb-audio enable_msi=1

After a reboot the problem still persists. I also tried another suggestion from this forum:

options snd-usb-audio nrpacks=1

This doesn't work either. I tried to change settings in /etc/security/limits.conf, which looks like this:

@audio          -       rtprio          99 
@audio          -       nice           -10
@audio          -       memlock         250000

The USB sound card doesn't share a IRQ with another USB devices, as can be seen here:

$cat /proc/interrupts
           CPU0       CPU1       
  0:     124157          0   IO-APIC-edge      timer
  1:       2102          0   IO-APIC-edge      i8042
  8:        182          0   IO-APIC-edge      rtc0
  9:        523          0   IO-APIC-fasteoi   acpi
 12:       3780          0   IO-APIC-edge      i8042
 14:      15944          0   IO-APIC-edge      ata_piix
 15:       5177          0   IO-APIC-edge      ata_piix
 16:      29001          0   IO-APIC-fasteoi   uhci_hcd:usb5, firewire_ohci, nvidia
 17:          0          0   IO-APIC-fasteoi   mmc0
 18:          0          0   IO-APIC-fasteoi   uhci_hcd:usb4
 19:      44788          0   IO-APIC-fasteoi   uhci_hcd:usb3
 23:        387          0   IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb2
 28:       1608          0   PCI-MSI-edge      eth0
 29:        932          0   PCI-MSI-edge      hda_intel
 30:          0          0   PCI-MSI-edge      iwl3945
NMI:          0          0   Non-maskable interrupts
LOC:      22401      65060   Local timer interrupts
SPU:          0          0   Spurious interrupts
PMI:          0          0   Performance monitoring interrupts
PND:          0          0   Performance pending work
RES:      89856     104215   Rescheduling interrupts
CAL:       1409        563   Function call interrupts
TLB:       1733       2536   TLB shootdowns
TRM:          0          0   Thermal event interrupts
THR:          0          0   Threshold APIC interrupts
MCE:          0          0   Machine check exceptions
MCP:          2          2   Machine check polls
ERR:          0
MIS:          0
$ lsusb 
Bus 003 Device 002: ID 046d:c03d Logitech, Inc. M-BT96a Pilot Optical Mouse
[b]Bus 003 Device 003: ID 08bb:2706 Texas Instruments Japan [/b]
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 002: ID 07ab:fc88 Freecom Technologies 
Bus 001 Device 006: ID 05e1:0501 Syntek Semiconductor Co., Ltd DC-1125 Webcam
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 002: ID 046d:c317 Logitech, Inc. Wave Corded Keyboard
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

Any other suggestions?

I even tried to disable the internal sound card by blacklisting it:

blacklist snd-hda-intel

.. but still no success sad

Last edited by boomerang (2010-04-19 20:04:33)

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#4 2010-04-20 21:19:19

boomerang
Member
Registered: 2010-04-18
Posts: 10

Re: [SOLVED] Audio dropouts with USB sound card

I saw a possibly related bug here. Kernel26-lts is compiled with the option CONFIG_USB_EHCI_TT_NEWSCHED enabled:

$ zcat /proc/config.gz | grep CONFIG_USB_EHCI_TT
CONFIG_USB_EHCI_TT_NEWSCHED=y

I tried this kernel, but the problem still persists.. Could this be another kernel issue? No matter what player or audio server (Pulseaudio, ALSA, JACK) I use, this problem occurs.

Last edited by boomerang (2010-04-20 21:23:34)

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#5 2010-04-20 21:37:49

lilsirecho
Veteran
Registered: 2003-10-24
Posts: 5,000

Re: [SOLVED] Audio dropouts with USB sound card

Perhaps you need to try a powered hub on the USB port for audio?


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#6 2010-04-25 17:47:00

boomerang
Member
Registered: 2010-04-18
Posts: 10

Re: [SOLVED] Audio dropouts with USB sound card

I will mark this thread as SOLVED.

I just found out that the nvidia driver was the cause of the audio dropouts. I'm now using the nouveau driver instead (using the installation instructions in the Arch wiki), and the problem is solved. Thanks for the other suggestions!

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