Problems or bugs in snd-usb-audio.ko

Problems or bugs in snd-usb-audio.ko

[Smery]

Hello,
        I have an USB 2.0 device with one Audio Class interface.
snd_snd-usb_audio.ko detects it and register the corresponding card.
But there seems to be some problems with in snd-usb-audio module when
reading from this device, (while another USB 1.1 device work fine).

My kernel version is: 2.6.12-1.1372_FC3 (I also tried many other kernels)

I would really appreciate any help! It's very important to get this card
working! I can code/debug everything you want to try.

Just let me know as soon as possible. Below is the issue in detail.

$ amixer -c 1 contents
numid=1,iface=MIXER,name='Mic Capture Switch'
  ; type=BOOLEAN,access=rw---,values=1
  : values=on
numid=2,iface=MIXER,name='Mic Capture Volume'
  ; type=INTEGER,access=rw---,values=1,min=0,max=3,step=0
  : values=0

$ arecord -l
  card 1: default [USB 2.0 Video ], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

$ amixer -c 1 cset numid=2 3
numid=2,iface=MIXER,name='Mic Capture Volume'
  ; type=INTEGER,access=rw---,values=1,min=0,max=3,step=0
  : values=3

When recording, it seems there are I/O problems:
$ arecord -d 10 -D hw:1,0 foobar.wav
Recording WAVE 'foobar.wav' : Unsigned 8 bit, Rate 8000 Hz, Mono
arecord: pcm_read:1196: read error: Input/output error

And the file is 44 bytes (just the header):

$ls -l foobar.wav
-rw-r--r--  1 luca luca 44 31 ago 19:12 foobar.wav

$ file foobar.wav
foobar.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 8 bit, mono 8000 Hz

Below is the Interface Descriptor:
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      1 Control Device
      bInterfaceProtocol      0
      iInterface              0
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               1.00
        wTotalLength           38
        bInCollection           1
        baInterfaceNr( 0)       2
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             1
        wTerminalType      0x0201 Microphone
        bAssocTerminal          0
        bNrChannels             1
        wChannelConfig     0x0000
        iChannelNames           0
        iTerminal               0
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID             2
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bSourceID               3
        iTerminal               0
      AudioControl Interface Descriptor:
        bLength                 8
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                 3
        bSourceID               1
        bControlSize            1
        bmaControls( 0)      0x03
          Mute
          Volume
        iFeature                0
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0
      iInterface              0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            1
          Transfer Type            Isochronous
          Synch Type               none
          Usage Type               Data
        wMaxPacketSize     0x0000  bytes 0 once
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0
      iInterface              0
      AudioControl Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           2
        bDelay                  1 frames
        wFormatTag              2 PCM8
      AudioControl Interface Descriptor:
        bLength                11
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             1
        bSubframeSize           1
        bBitResolution          8
        bSamFreqType            1 Discrete
        tSamFreq[ 0]         8000
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            1
          Transfer Type            Isochronous
          Synch Type               none
          Usage Type               Data
        wMaxPacketSize     0x0009  bytes 9 once
        bInterval               4
        AudioControl Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x00
          bLockDelayUnits         0 Undefined
          wLockDelay              0 Undefined


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Re: Problems or bugs in snd-usb-audio.ko

[Lee Revell]

On Wed, 2005-08-31 at 19:26 +0000, Smery wrote:
> When recording, it seems there are I/O problems:
> $ arecord -d 10 -D hw:1,0 foobar.wav
> Recording WAVE 'foobar.wav' : Unsigned 8 bit, Rate 8000 Hz, Mono
> arecord: pcm_read:1196: read error: Input/output error
> 
> And the file is 44 bytes (just the header):
> 
> $ls -l foobar.wav
> -rw-r--r--  1 luca luca 44 31 ago 19:12 foobar.wav 

Because your device probably doesn'y support 8 bit mono at 8000Hz, which
is the default format of arecord.  Use -D plughw:1,0 or specify a format
your device supports.

Lee



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Re: Problems or bugs in snd-usb-audio.ko

[Clemens Ladisch]

> On Wed, 2005-08-31 at 19:26 +0000, Smery wrote:
> > I have an USB 2.0 device with one Audio Class interface.
> > snd_snd-usb_audio.ko detects it and register the corresponding card.
> > But there seems to be some problems with in snd-usb-audio module when
> > reading from this device, (while another USB 1.1 device work fine).
> >
> > My kernel version is: 2.6.12-1.1372_FC3 (I also tried many other kernels)

Please make sure you're using 2.6.13 and the latest ALSA (1.0.10rc1).

Lee Revell wrote:
> Because your device probably doesn'y support 8 bit mono at 8000Hz, which
> is the default format of arecord.

As it happens, this is the only format supported by this device.
arecord would have complained if the format wasn't supported.


HTH
Clemens



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Re: Problems or bugs in snd-usb-audio.ko

[Smery]

On Thu, Sep 01, 2005 at 10:11:48AM +0200, Clemens Ladisch wrote:
> > On Wed, 2005-08-31 at 19:26 +0000, Smery wrote:
> > > I have an USB 2.0 device with one Audio Class interface.
> > > snd_snd-usb_audio.ko detects it and register the corresponding card.
> > > But there seems to be some problems with in snd-usb-audio module when
> > > reading from this device, (while another USB 1.1 device work fine).
> > >
> > > My kernel version is: 2.6.12-1.1372_FC3 (I also tried many other kernels)
>
> Please make sure you're using 2.6.13 and the latest ALSA (1.0.10rc1).

Okay. I'll try.

>
> Lee Revell wrote:
> > Because your device probably doesn'y support 8 bit mono at 8000Hz, which
> > is the default format of arecord.
>
> As it happens, this is the only format supported by this device.
> arecord would have complained if the format wasn't supported.

Yes, that's the only supported format.

Thanks


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Re: Problems or bugs in snd-usb-audio.ko

[Lee Revell]

On Thu, 2005-09-01 at 11:08 +0000, Smery wrote:
> > Lee Revell wrote:
> > > Because your device probably doesn'y support 8 bit mono at 8000Hz, which
> > > is the default format of arecord.
> >
> > As it happens, this is the only format supported by this device.
> > arecord would have complained if the format wasn't supported.
> 
> Yes, that's the only supported format.
> 

Pardon my ignorance but what's the point of a soundcard that only does 8
bit mono at 8000Hz?  VoIP?

Don't modern VoIP apps like Skype support better quality than that?

Lee



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Re: Problems or bugs in snd-usb-audio.ko

[Clemens Ladisch]

Lee Revell wrote:
> Pardon my ignorance but what's the point of a soundcard that only does 8
> bit mono at 8000Hz?  VoIP?

The product name ("USB 2.0 Video") seems to indicate a webcam or
something like that.  Otherwise, using USB 2.0 for 8000 bytes/s would
look like a _somewhat_ strange design decision. :-)


Regards,
Clemens



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Re: Problems or bugs in snd-usb-audio.ko

[Smery]

> Lee Revell wrote:
> > Pardon my ignorance but what's the point of a soundcard that only does 8
> > bit mono at 8000Hz?  VoIP?
>
> The product name ("USB 2.0 Video") seems to indicate a webcam or
> something like that.  Otherwise, using USB 2.0 for 8000 bytes/s would
> look like a _somewhat_ strange design decision. :-)

Correct. I am doing some test with the latest alsa modules. I will let you know.

Thanks.


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Re: Problems or bugs in snd-usb-audio.ko

[Clemens Ladisch]

Smery wrote:
> Okay. I tried the latest ALSA and I obtain the same error as above:
>
> $ arecord -d 10 -D hw:1,0 foobar.wav
> Recording WAVE 'foobar.wav' : Unsigned 8 bit, Rate 8000 Hz, Mono
> arecord: pcm_read:1263: read error: Input/output error

It seems the device doesn't actually send any data.

Please compile --with-debug=yes and see whether there are any messages
in the system log.


It may be possible that it needs some initialization in the video part
before it does anything.

> Any other ideas?

Do you have the source code of the Windows driver?  Or does the audio
part work with Microsoft's standard driver?


Regards,
Clemens



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Re: Problems or bugs in snd-usb-audio.ko

[Smery]

> Lee Revell wrote:
> > Pardon my ignorance but what's the point of a soundcard that only does 8
> > bit mono at 8000Hz?  VoIP?
>
> The product name ("USB 2.0 Video") seems to indicate a webcam or
> something like that.  Otherwise, using USB 2.0 for 8000 bytes/s would
> look like a _somewhat_ strange design decision. :-)

Okay. I tried the latest ALSA and I obtain the same error as above:

$ arecord -d 10 -D hw:1,0 foobar.wav
Recording WAVE 'foobar.wav' : Unsigned 8 bit, Rate 8000 Hz, Mono
arecord: pcm_read:1263: read error: Input/output error

Any other ideas? Could you also give me a starting point where to
look at in the code? I would appreciate your help and I am available
for help.

Thanks


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