Unable to achieve a low latency with Focusrite Scarlett 2i2

[ehdee]

Hey,

I was pretty optimistic after reading the post regarding blacklisting the Intel chip, however unfortunately it didn't make any difference in terms of Xruns (although it did remove the option in qjackctl for the device, so I can assume it did actually disable it!).

In addition to running my script from earlier, I've also followed the instructions at http://darksound.co.uk/?p=256 to disable some further features. I also removed pretty much everything that autostarts in the "Session and Startup" section of the Ubuntu Studio settings.

I'm still getting these Xruns at regular intervals. It doesn't sound at all like the machine is 'struggling' at any point before or after the Xruns - no stuttering or popping (until the Xrun itself!).

The only thing I can think of now, is the USB cable I'm using is pretty old. I've read somewhere though that I shouldn't be able to select 96kHz if the cable is incompatible. I think this is desperation speaking however!

One other thing I noticed - if I don't manually disable networking through the GUI before my running my script, my WiFi connection persists for some reason. I've been making sure to manually disable it each time before running the script.

Thanks again for the support. I've still not tried to install Ubuntu Studio on my desktop, however am going to do so soon. Would rather be able to use it on my laptop however.

I've not yet attempted to troubleshoot the Xrun messages in qjackctl, however this may be another option for me to investigate.

ehdee

[ehdee]

I think I can happily eliminate any potential issues with the hardware interface itself: I booted my desktop from a live USB containing 12.10, and it worked fine with the Focusrite Scarlett @ 96kHz with ~2msec latency. I recorded a single track beyond 4mins without and Xruns, and some additional tracks on top as well.

My desktop PC is actually a very low powered device - an Acer Revo R3700. And it worked, with me booting off a live USB and without any tweaking whatsoever!

I guess I could try doing the same on the laptop ie. testing when using Ubuntu Studio in 'live' mode, and see what happens.

[CrocoDuck]

As the xruns seems regular (refer to the messages window in qjacktl to view accurate infos and statistics) everything smells like "something causing regular interrupts". I don't have a clear idea on how to understand what could be this "something", except looking at /proc/interrupts (in order to understand what has the same IRQ of your soundcard) and htop to have a look at processes. Have you tried by using your Scarlett into some other USB port? Commonly there are multiple hubs/controller/bus inside the computer, so what happens using a port may not happen in another port. On my desktop computer I have some usb port that are unable to make my external usb drive work properly, especially if I use a longer cable (the hard drive turns on, but the system can't mount it), so the cable could be a protagonist... but as you said... desperation speaking... especially if the xruns are regular...

Yes, investigating the qjackctl's messages can bring us to understand something.

So sorry but my english is bad (I'm not a native speaker, as you probably guessed) and I want to make sure about a thing... So I must make you a trivial question : have you installed ubuntu studio on your laptop or are you testing using an USB bootable drive?

P.S. : lsusb -v can bring us some more info on what is going on USB hardware inside the machine. Run it with your Scarlett plugged. Have another look at our favourite page, http://wiki.linuxmusicians.com/doku...._configuration , paragraph "Solve IRQ Conflict by Unbinding devices". I think that it contains some good hint that can bring us to understand what interferes with the soundcard.

[Sylos]

Just a thought (a little stab in the dark really) but do you have any power stepping or power saving features enabled? It could be that something like that might cause your problem.

Also, as Crocoduck said - its worth looking at which USB hub you connecting to and whet else might be using it. Try different hubs and check in cat /proc/interrupts to see what else shares the same IRQ.

Good luck.

[ehdee]

Hey,

All of my testing on the laptop has been with an installed version of 12.10 x64, however I did try once using a Live USB as I was curious (it seemed to work on my desktop this way!), however it was much the same.

It would appear that there are two USB buses on the laptop and I've tried both, and there doesn't appear to be any difference. Out of curiousity I tried testing on another Dell laptop (Inspiron 1534) and everything was much the same.

Interestingly there is an option for 'Power' in the "Session and Startup" section in the Ubuntu Studio settings. This was one of the few settings I didn't remove. Perhaps I can try this tonight!

[Sylos]

The i series intel chips (i3, i5, i7) have speed stepping capabilities that are normally enabled on laptops to save power. I have read on some pro-audio forums that this can cause some bad audio pops/crackles (xruns to us linux folk) and therefore should be disabled when you are recording. If you cant find an option of how to do this you can:

1. Look in BIOS to see if there are options to disable it on the MOBO; or
2. Have a look in the software under "cpu" or some such search term and look for additional software to allow you to set it. I installed a little something for it but Im not at my linux box and cant remember the name of it.

Also, can you post the output of cat /proc/interrupts and lsusb -vvv (when your soundcard is plugged in and powered on).

Cheers

[ehdee]

Hi,

I did a bit of research based on your post and reckon you mean the Intel SmartStep BIOS feature. Having disabled this cpufreq-info is no longer able to report back on the clockspeed of the cores, however it can be assumed that they are now running at full speed as opposed to any power saving mode.

It doesn't appear to have helped so far, however it sounds like a good idea to keep the feature disabled for now.

My interrupts:

           CPU0       CPU1       CPU2       CPU3       
  0:        132          0          0          0   IO-APIC-edge      timer
  1:         16         45         17         46   IO-APIC-edge      i8042
  8:          0          1          0          0   IO-APIC-edge      rtc0
  9:          0          2          0          1   IO-APIC-fasteoi   acpi
 12:       3035      10368       3062      10368   IO-APIC-edge      i8042
 16:     295149         31     295131         34   IO-APIC-fasteoi   ehci_hcd:usb1
 17:          0          0          0          0   IO-APIC-fasteoi   brcmsmac
 23:          7         14          8         16   IO-APIC-fasteoi   ehci_hcd:usb2
 44:          0          0          0          0   PCI-MSI-edge      pciehp
 45:      17242       1613      17225       1616   PCI-MSI-edge      ahci
 47:          4          4          4          3   PCI-MSI-edge      mei
 48:        329        395        340        396   PCI-MSI-edge      radeon
NMI:         30         72         13         30   Non-maskable interrupts
LOC:      35332      83546      16090      32721   Local timer interrupts
SPU:          0          0          0          0   Spurious interrupts
PMI:         30         72         13         30   Performance monitoring interrupts
IWI:          0          0          0          0   IRQ work interrupts
RTR:          3          0          0          0   APIC ICR read retries
RES:      60349      13836       1524       1006   Rescheduling interrupts
CAL:        285        357        346        336   Function call interrupts
TLB:        337        225        240        158   TLB shootdowns
TRM:          0          0          0          0   Thermal event interrupts
THR:          0          0          0          0   Threshold APIC interrupts
MCE:          0          0          0          0   Machine check exceptions
MCP:          4          4          4          4   Machine check polls
ERR:          0
MIS:          0

And the output of lsusb:

Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            9 Hub
  bDeviceSubClass         0 Unused
  bDeviceProtocol         1 Single TT
  bMaxPacketSize0        64
  idVendor           0x8087 Intel Corp.
  idProduct          0x0020 Integrated Rate Matching Hub
  bcdDevice            0.00
  iManufacturer           0 
  iProduct                0 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           25
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xe0
      Self Powered
      Remote Wakeup
    MaxPower                0mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         9 Hub
      bInterfaceSubClass      0 Unused
      bInterfaceProtocol      0 Full speed (or root) hub
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0001  1x 1 bytes
        bInterval              12

Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            9 Hub
  bDeviceSubClass         0 Unused
  bDeviceProtocol         1 Single TT
  bMaxPacketSize0        64
  idVendor           0x8087 Intel Corp.
  idProduct          0x0020 Integrated Rate Matching Hub
  bcdDevice            0.00
  iManufacturer           0 
  iProduct                0 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           25
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xe0
      Self Powered
      Remote Wakeup
    MaxPower                0mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         9 Hub
      bInterfaceSubClass      0 Unused
      bInterfaceProtocol      0 Full speed (or root) hub
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0002  1x 2 bytes
        bInterval              12

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            9 Hub
  bDeviceSubClass         0 Unused
  bDeviceProtocol         0 Full speed (or root) hub
  bMaxPacketSize0        64
  idVendor           0x1d6b Linux Foundation
  idProduct          0x0002 2.0 root hub
  bcdDevice            3.05
  iManufacturer           3 
  iProduct                2 
  iSerial                 1 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           25
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xe0
      Self Powered
      Remote Wakeup
    MaxPower                0mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         9 Hub
      bInterfaceSubClass      0 Unused
      bInterfaceProtocol      0 Full speed (or root) hub
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0004  1x 4 bytes
        bInterval              12

Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            9 Hub
  bDeviceSubClass         0 Unused
  bDeviceProtocol         0 Full speed (or root) hub
  bMaxPacketSize0        64
  idVendor           0x1d6b Linux Foundation
  idProduct          0x0002 2.0 root hub
  bcdDevice            3.05
  iManufacturer           3 
  iProduct                2 
  iSerial                 1 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           25
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xe0
      Self Powered
      Remote Wakeup
    MaxPower                0mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         9 Hub
      bInterfaceSubClass      0 Unused
      bInterfaceProtocol      0 Full speed (or root) hub
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0004  1x 4 bytes
        bInterval              12

Bus 001 Device 003: ID 1235:8006 Novation EMS 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2 ?
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x1235 Novation EMS
  idProduct          0x8006 
  bcdDevice            0.cc
  iManufacturer           1 
  iProduct                2 
  iSerial                 0 
  bNumConfigurations      2
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          287
    bNumInterfaces          4
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Association:
      bLength                 8
      bDescriptorType        11
      bFirstInterface         0
      bInterfaceCount         3
      bFunctionClass          1 Audio
      bFunctionSubClass       0 
      bFunctionProtocol      32 
      iFunction               0 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      1 Control Device
      bInterfaceProtocol     32 
      iInterface              2 
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               2.00
        bCategory               8
        wTotalLength          119
        bmControl            0x00
      AudioControl Interface Descriptor:
        bLength                 8
        bDescriptorType        36
        bDescriptorSubtype     10 (CLOCK_SOURCE)
        bClockID               41
        bmAttributes         0x03 Internal programmable Clock 
        bmControls           0x07
          Clock Frequency Control (read/write)
          Clock Validity Control (read-only)
        bAssocTerminal          0
        iClockSource            9 
      AudioControl Interface Descriptor:
        bLength                 8
        bDescriptorType        36
        bDescriptorSubtype     11 (CLOCK_SELECTOR)
        bUnitID                40
        bNrInPins               1
        baCSourceID( 0)        41
        bmControls           0x03
          Clock Selector Control (read/write)
        iClockSelector          8 
      AudioControl Interface Descriptor:
        bLength                17
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             2
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bCSourceID             40
        bNrChannels             2
        bmChannelConfig   0x00000000
        bmControls    0x0000
        iChannelNames          15 
        iTerminal               6 
      AudioControl Interface Descriptor:
        bLength                18
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                10
        bSourceID               2
        bmaControls( 0)      0x00000000
        bmaControls( 1)      0x00000000
        bmaControls( 2)      0x00000000
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID            20
        wTerminalType      0x0301 Speaker
        bAssocTerminal          0
        bSourceID              10
        bCSourceID             40
        bmControls         0x0000
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                17
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             1
        wTerminalType      0x0201 Microphone
        bAssocTerminal          0
        bCSourceID             40
        bNrChannels             2
        bmChannelConfig   0x00000000
        bmControls    0x0000
        iChannelNames          33 
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                18
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                11
        bSourceID               1
        bmaControls( 0)      0x00000000
        bmaControls( 1)      0x00000000
        bmaControls( 2)      0x00000000
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID            22
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bSourceID              11
        bCSourceID             40
        bmControls         0x0000
        iTerminal               7 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0006  1x 6 bytes
        bInterval               8
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              4 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       1
      bNumEndpoints           2
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              4 
      AudioStreaming Interface Descriptor:
        bLength                16
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           2
        bmControls           0x00
        bFormatType             1
        bmFormats               1
          PCM
        bNrChannels             2
        bmChannelConfig   0x00000000
        iChannelNames          15 
      AudioStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bSubslotSize            4
        bBitResolution         24
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               1
        AudioControl Endpoint Descriptor:
          bLength                 8
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x00
          bmControls           0x00
          bLockDelayUnits         2 Decoded PCM samples
          wLockDelay              8
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes           17
          Transfer Type            Isochronous
          Synch Type               None
          Usage Type               Feedback
        wMaxPacketSize     0x0004  1x 4 bytes
        bInterval               4
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              5 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              5 
      AudioStreaming Interface Descriptor:
        bLength                16
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink          22
        bmControls           0x00
        bFormatType             1
        bmFormats               1
          PCM
        bNrChannels             2
        bmChannelConfig   0x00000000
        iChannelNames          33 
      AudioStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bSubslotSize            4
        bBitResolution         24
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               1
        AudioControl Endpoint Descriptor:
          bLength                 8
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x00
          bmControls           0x00
          bLockDelayUnits         2 Decoded PCM samples
          wLockDelay              8
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        3
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass       254 Application Specific Interface
      bInterfaceSubClass      1 Device Firmware Update
      bInterfaceProtocol      1 
      iInterface             12 
      Device Firmware Upgrade Interface Descriptor:
        bLength                             9
        bDescriptorType                    33
        bmAttributes                        7
          Will Not Detach
          Manifestation Tolerant
          Upload Supported
          Download Supported
        wDetachTimeout                    250 milliseconds
        wTransferSize                      64 bytes
        bcdDFUVersion                   1.10
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          287
    bNumInterfaces          4
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Association:
      bLength                 8
      bDescriptorType        11
      bFirstInterface         0
      bInterfaceCount         3
      bFunctionClass          1 Audio
      bFunctionSubClass       0 
      bFunctionProtocol      32 
      iFunction               0 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      1 Control Device
      bInterfaceProtocol     32 
      iInterface              2 
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               2.00
        bCategory               8
        wTotalLength          119
        bmControl            0x00
      AudioControl Interface Descriptor:
        bLength                 8
        bDescriptorType        36
        bDescriptorSubtype     10 (CLOCK_SOURCE)
        bClockID               41
        bmAttributes         0x03 Internal programmable Clock 
        bmControls           0x07
          Clock Frequency Control (read/write)
          Clock Validity Control (read-only)
        bAssocTerminal          0
        iClockSource            9 
      AudioControl Interface Descriptor:
        bLength                 8
        bDescriptorType        36
        bDescriptorSubtype     11 (CLOCK_SELECTOR)
        bUnitID                40
        bNrInPins               1
        baCSourceID( 0)        41
        bmControls           0x03
          Clock Selector Control (read/write)
        iClockSelector          8 
      AudioControl Interface Descriptor:
        bLength                17
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             2
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bCSourceID             40
        bNrChannels             2
        bmChannelConfig   0x00000000
        bmControls    0x0000
        iChannelNames          15 
        iTerminal               6 
      AudioControl Interface Descriptor:
        bLength                18
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                10
        bSourceID               2
        bmaControls( 0)      0x00000000
        bmaControls( 1)      0x00000000
        bmaControls( 2)      0x00000000
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID            20
        wTerminalType      0x0301 Speaker
        bAssocTerminal          0
        bSourceID              10
        bCSourceID             40
        bmControls         0x0000
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                17
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             1
        wTerminalType      0x0201 Microphone
        bAssocTerminal          0
        bCSourceID             40
        bNrChannels             2
        bmChannelConfig   0x00000000
        bmControls    0x0000
        iChannelNames          33 
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                18
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                11
        bSourceID               1
        bmaControls( 0)      0x00000000
        bmaControls( 1)      0x00000000
        bmaControls( 2)      0x00000000
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID            22
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bSourceID              11
        bCSourceID             40
        bmControls         0x0000
        iTerminal               7 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0006  1x 6 bytes
        bInterval               8
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              4 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       1
      bNumEndpoints           2
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              4 
      AudioStreaming Interface Descriptor:
        bLength                16
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           2
        bmControls           0x00
        bFormatType             1
        bmFormats               1
          PCM
        bNrChannels             2
        bmChannelConfig   0x00000000
        iChannelNames          15 
      AudioStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bSubslotSize            4
        bBitResolution         24
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               1
        AudioControl Endpoint Descriptor:
          bLength                 8
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x00
          bmControls           0x00
          bLockDelayUnits         2 Decoded PCM samples
          wLockDelay              8
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes           17
          Transfer Type            Isochronous
          Synch Type               None
          Usage Type               Feedback
        wMaxPacketSize     0x0004  1x 4 bytes
        bInterval               4
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              5 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              5 
      AudioStreaming Interface Descriptor:
        bLength                16
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink          22
        bmControls           0x00
        bFormatType             1
        bmFormats               1
          PCM
        bNrChannels             2
        bmChannelConfig   0x00000000
        iChannelNames          33 
      AudioStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bSubslotSize            4
        bBitResolution         24
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               1
        AudioControl Endpoint Descriptor:
          bLength                 8
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x00
          bmControls           0x00
          bLockDelayUnits         2 Decoded PCM samples
          wLockDelay              8
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        3
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass       254 Application Specific Interface
      bInterfaceSubClass      1 Device Firmware Update
      bInterfaceProtocol      1 
      iInterface             12 
      Device Firmware Upgrade Interface Descriptor:
        bLength                             9
        bDescriptorType                    33
        bmAttributes                        7
          Will Not Detach
          Manifestation Tolerant
          Upload Supported
          Download Supported
        wDetachTimeout                    250 milliseconds
        wTransferSize                      64 bytes
        bcdDFUVersion                   1.10

Bus 001 Device 004: ID 0c45:641d Microdia 1.3 MPixel Integrated Webcam
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2 ?
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x0c45 Microdia
  idProduct          0x641d 1.3 MPixel Integrated Webcam
  bcdDevice            1.26
  iManufacturer           2 
  iProduct                1 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          665
    bNumInterfaces          2
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    ** UNRECOGNIZED:  28 ff 42 49 53 54 00 01 06 01 10 00 00 00 00 00 d1 10 f4 01 d2 11 f4 01 d3 12 f4 01 d4 13 f4 01 d5 14 f4 01 d6 15 f4 01
    Interface Association:
      bLength                 8
      bDescriptorType        11
      bFirstInterface         0
      bInterfaceCount         2
      bFunctionClass         14 Video
      bFunctionSubClass       3 Video Interface Collection
      bFunctionProtocol       0 
      iFunction               4 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      1 Video Control
      bInterfaceProtocol      0 
      iInterface              4 
      VideoControl Interface Descriptor:
        bLength                13
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdUVC               1.00
        wTotalLength          103
        dwClockFrequency       15.000000MHz
        bInCollection           1
        baInterfaceNr( 0)       1
      VideoControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID             2
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bSourceID               5
        iTerminal               0 
      VideoControl Interface Descriptor:
        bLength                26
        bDescriptorType        36
        bDescriptorSubtype      6 (EXTENSION_UNIT)
        bUnitID                 4
        guidExtensionCode         {7033f028-1163-2e4a-ba2c-6890eb334016}
        bNumControl             8
        bNrPins                 1
        baSourceID( 0)          3
        bControlSize            1
        bmControls( 0)       0x1f
        iExtension              0 
      VideoControl Interface Descriptor:
        bLength                26
        bDescriptorType        36
        bDescriptorSubtype      6 (EXTENSION_UNIT)
        bUnitID                 5
        guidExtensionCode         {c385b80f-c268-4745-90f7-8f47579d95fc}
        bNumControl             4
        bNrPins                 1
        baSourceID( 0)          4
        bControlSize            1
        bmControls( 0)       0x0f
        iExtension              0 
      VideoControl Interface Descriptor:
        bLength                18
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             1
        wTerminalType      0x0201 Camera Sensor
        bAssocTerminal          0
        iTerminal               0 
        wObjectiveFocalLengthMin      0
        wObjectiveFocalLengthMax      0
        wOcularFocalLength            0
        bControlSize                  3
        bmControls           0x00000000
      VideoControl Interface Descriptor:
        bLength                11
        bDescriptorType        36
        bDescriptorSubtype      5 (PROCESSING_UNIT)
      Warning: Descriptor too short
        bUnitID                 3
        bSourceID               1
        wMaxMultiplier          0
        bControlSize            2
        bmControls     0x0000177f
          Brightness
          Contrast
          Hue
          Saturation
          Sharpness
          Gamma
          White Balance Temperature
          Backlight Compensation
          Gain
          Power Line Frequency
          White Balance Temperature, Auto
        iProcessing             0 
        bmVideoStandards     0x41
          None
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0010  1x 16 bytes
        bInterval               6
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      VideoStreaming Interface Descriptor:
        bLength                            14
        bDescriptorType                    36
        bDescriptorSubtype                  1 (INPUT_HEADER)
        bNumFormats                         1
        wTotalLength                      379
        bEndPointAddress                  129
        bmInfo                              0
        bTerminalLink                       2
        bStillCaptureMethod                 2
        bTriggerSupport                     0
        bTriggerUsage                       0
        bControlSize                        1
        bmaControls( 0)                    27
      VideoStreaming Interface Descriptor:
        bLength                            27
        bDescriptorType                    36
        bDescriptorSubtype                  4 (FORMAT_UNCOMPRESSED)
        bFormatIndex                        1
        bNumFrameDescriptors                7
        guidFormat                            {59555932-0000-1000-8000-00aa00389b71}
        bBitsPerPixel                      16
        bDefaultFrameIndex                  1
        bAspectRatioX                       0
        bAspectRatioY                       0
        bmInterlaceFlags                 0x00
          Interlaced stream or variable: No
          Fields per frame: 2 fields
          Field 1 first: No
          Field pattern: Field 1 only
          bCopyProtect                      0
      VideoStreaming Interface Descriptor:
        bLength                            46
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         1
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            640
        wHeight                           480
        dwMinBitRate                 24576000
        dwMaxBitRate                147456000
        dwMaxVideoFrameBufferSize      614400
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  5
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            500000
        dwFrameInterval( 2)            666666
        dwFrameInterval( 3)           1000000
        dwFrameInterval( 4)           2000000
      VideoStreaming Interface Descriptor:
        bLength                            46
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         2
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            352
        wHeight                           288
        dwMinBitRate                  8110080
        dwMaxBitRate                 48660480
        dwMaxVideoFrameBufferSize      202752
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  5
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            500000
        dwFrameInterval( 2)            666666
        dwFrameInterval( 3)           1000000
        dwFrameInterval( 4)           2000000
      VideoStreaming Interface Descriptor:
        bLength                            46
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         3
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            320
        wHeight                           240
        dwMinBitRate                  6144000
        dwMaxBitRate                 36864000
        dwMaxVideoFrameBufferSize      153600
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  5
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            500000
        dwFrameInterval( 2)            666666
        dwFrameInterval( 3)           1000000
        dwFrameInterval( 4)           2000000
      VideoStreaming Interface Descriptor:
        bLength                            46
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         4
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            176
        wHeight                           144
        dwMinBitRate                  2027520
        dwMaxBitRate                 12165120
        dwMaxVideoFrameBufferSize       50688
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  5
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            500000
        dwFrameInterval( 2)            666666
        dwFrameInterval( 3)           1000000
        dwFrameInterval( 4)           2000000
      VideoStreaming Interface Descriptor:
        bLength                            46
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         5
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            160
        wHeight                           120
        dwMinBitRate                  1536000
        dwMaxBitRate                  9216000
        dwMaxVideoFrameBufferSize       38400
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  5
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            500000
        dwFrameInterval( 2)            666666
        dwFrameInterval( 3)           1000000
        dwFrameInterval( 4)           2000000
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         6
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                           1024
        wHeight                           768
        dwMinBitRate                 62914560
        dwMaxBitRate                113246208
        dwMaxVideoFrameBufferSize     1572864
        dwDefaultFrameInterval        1111111
        bFrameIntervalType                  2
        dwFrameInterval( 0)           1111111
        dwFrameInterval( 1)           2000000
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         7
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                           1280
        wHeight                          1024
        dwMinBitRate                104857600
        dwMaxBitRate                188743680
        dwMaxVideoFrameBufferSize     2621440
        dwDefaultFrameInterval        1111111
        bFrameIntervalType                  2
        dwFrameInterval( 0)           1111111
        dwFrameInterval( 1)           2000000
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  3 (STILL_IMAGE_FRAME)
        bEndpointAddress                    0
        bNumImageSizePatterns               7
        wWidth( 0)                       1280
        wHeight( 0)                      1024
        wWidth( 1)                       1024
        wHeight( 1)                       768
        wWidth( 2)                        640
        wHeight( 2)                       480
        wWidth( 3)                        352
        wHeight( 3)                       288
        wWidth( 4)                        320
        wHeight( 4)                       240
        wWidth( 5)                        176
        wHeight( 5)                       144
        wWidth( 6)                        160
        wHeight( 6)                       120
        bNumCompressionPatterns             7
      VideoStreaming Interface Descriptor:
        bLength                             6
        bDescriptorType                    36
        bDescriptorSubtype                 13 (COLORFORMAT)
        bColorPrimaries                     1 (BT.709,sRGB)
        bTransferCharacteristics            1 (BT.709)
        bMatrixCoefficients                 4 (SMPTE 170M (BT.601))
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0080  1x 128 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       2
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0100  1x 256 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       3
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0320  1x 800 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       4
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0b20  2x 800 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       5
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x1320  3x 800 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       6
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x1400  3x 1024 bytes
        bInterval               1

[Sylos]

Well it look like your soundcard is on USB hub1 - which in turn is on IRQ 16. That in itself isnt a bad thing, but it seems that you are getting a whole bucket load of interrupts on that IRQ. This is getting a little beyond my depth of knowledge but it seems that this could be the cause of your problem.

Have you tried the rtirq script tweaking?

Cheers

[ehdee]

Hi,

Thanks for looking at the outputs. I wasn't 100% on how to determine which irq the soundcard was using however you've confirmed what I was thinking about it being on 16.

I've not read anything about rtirq yet (apologies if this was suggested earlier in the thread), however I'll make this my next line of investigation!

[Sylos]

Hi,

Thanks for looking at the outputs. I wasn't 100% on how to determine which irq the soundcard was using however you've confirmed what I was thinking about it being on 16.

I've not read anything about rtirq yet (apologies if this was suggested earlier in the thread), however I'll make this my next line of investigation!

As far as the IRQ is concerned I cant be sure from that output (thats my bad as I forgot to ask for the output of lspci -v). If you do that command as well you will be able to see which IRQ is assigned to the USB device by cross referencing its Device ID (as shown from lsusb) with those ID's listed from lspci -v. In this case the USB device ID appears to be "Bus 001 Device 003: ID 1235". This should allow you to see exactly what IRQ it is. Looking at the output you already gave it appears that Bus 001 is IRQ 16 so I assume that device 003 (your soundcard) will be on 16. You could always do the extra check just to be sure.

It's still a mystery to me why you are having these problems. It might be worth trying a different audio distro from a Live CD to see if that suffers the same problem. If not then it might give an indication of what is causing the issue.

Cheers