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Setting default format using .inf file (USB Audio)

    Question

  • I have a USB audio device and I am writing an inf file for it. Basically I have to do this instead of using the default Windows wdma_usb.inf for 2 reasons:

    1. This device must NOT become the default playback device (my inf solved this problem by not setting SetupPreferredAudioDevices)

    2. I need the default sound format to be set to 4 channel, 16 bit, 8000 Hz (instead of 4 channel, 16 bit, 24000 Hz)

     

    I looked at the sysfx example from WinDDK but I am not yet used to create inf files. Currently it doesn't work but I am not usre why. There are 2 elements that I am not sure about them and it is not easy to debug that.

     

    First, I am not sure about the value I have to set for PKEY_AudioEngine_OEMFormat. The value I set (trying to get 4 channels, 16 bit, 8000 Hz) is 41,00,8C,70,28,00,00,00,FE,FF,04,00,40,1F,00,00,00,FA,00,00,08,00,10,00,16,00,10,00,03,00,00,00,01,00,00,00,00,00,10,00,80,00,00,AA,00,38,9B,71.

    I am not sure this is the right value. Looking at the registry when I change this value in the Vista Digital Audio Interface Properties GUI, I see a very similar string but with some differences so maybe that is why it doesn't work (but I tried that string and it still didn't work).

     

    The other element I am confused about is how to prepare the use of that section:

    [OEMSettingsOverride.AddReg]
    HKR,"EP\\0", %PKEY_AudioEndpoint_Association%,,%KSNODETYPE_SPEAKER%
    HKR,"EP\\0", %PKEY_AudioEngine_OEMFormat%, %REG_BINARY%,
    41,00,8C,70,28,00,00,00,FE,FF,04,00,40,1F,00,00,00,FA,00,00,08,00,10,00,16,00,10,00,03,00,00,00,01,00,00,00,00,00,10,00,80,00,00,AA,00,38,9B,71

    HKR,"EP\\0", %PKEY_AudioEndpoint_Ext_UiClsid%,,%AUDIOENDPOINT_EXT_UI_CLSID%

     

    The other important part of my inf (I can post more is this is needed) is:

    ;============================================================================

    [USBAudio]
    Include=ks.inf,wdmaudio.inf
    Needs=KS.Registration,WDMAUDIO.Registration,mssysfx.CopyFilesAndRegister
    CopyFiles=USBAudio.CopyList
    AddReg=USBAudio.AddReg

    ;============================================================================

    [USBAudio.Interfaces]
    AddInterface=%KSCATEGORY_AUDIO%,"GLOBAL",USBAudio.Interface.Curve,
    AddInterface=%KSCATEGORY_RENDER%,"GLOBAL",USBAudio.Interface.Curve,
    AddInterface=%KSCATEGORY_CAPTURE%,"GLOBAL",USBAudio.Interface.Curve,
    ;============================================================================

    [USBAudio.Interface.Curve]
    AddReg=USBAudio.Interface.Addreg.Curve, USBAudio.SysFx.Render

    [USBAudio.Interface.AddReg.Curve]
    HKR,,FriendlyName,,%USB\VID_15C9&PID_0106&MI_01.DeviceDesc%
    HKR,,CurveType,1,01,00,00,00
    HKR,,CLSID,,%Proxy.CLSID%

    ;============================================================================

    [USBAudio.AddReg]
    HKR,,AssociatedFilters,,"wdmaud,redbook"
    HKR,,Driver,,USBAUDIO.sys
    HKR,,NTMPDriver,,"USBAUDIO.sys,sbemul.sys"

    HKR,,CLSID,,%Proxy.CLSID%

    HKR,Drivers,SubClasses,,"wave,midi,mixer,aux"

    HKR,Drivers\wave\wdmaud.drv, Driver,,wdmaud.drv
    HKR,Drivers\midi\wdmaud.drv, Driver,,wdmaud.drv
    HKR,Drivers\mixer\wdmaud.drv,Driver,,wdmaud.drv
    HKR,Drivers\aux\wdmaud.drv,Driver,,wdmaud.drv

    HKR,Drivers\wave\wdmaud.drv,Description,,%USBGenericDesc%
    HKR,Drivers\midi\wdmaud.drv,Description,,%WDM_MIDI%
    HKR,Drivers\mixer\wdmaud.drv,Description,,%USBGenericDesc%
    HKR,Drivers\aux\wdmaud.drv,Description,,%USBGenericDesc%

    HKLM,%MediaCategories%\%USBGUID.BassBoost%,Name,,%USBNode.BassBoost%
    HKLM,%MediaCategories%\%USBGUID.BassBoost%,Display,1,00,00,00,00
    HKLM,%MediaCategories%\%USBGUID.StereoExtend%,Name,,%USBNode.StereoExtend%
    HKLM,%MediaCategories%\%USBGUID.StereoExtend%,Display,1,00,00,00,00

     

    I tried to add AddInterface=%KSCATEGORY_TOPOLOGY%,"GLOBAL",USBAudio.PrimaryLineOutTopo in [USBAudio.Interfaces] and then in that section (USBAudio.PrimaryLineOutTopo ) I added the OEMSettingsOverride.AddReg but it didn't work. I am pretty sure that is not the right way to do it, I will continue to read about the subject but I would appreciate any help I could get about this.

     

    Thanks

    Thursday, April 10, 2008 3:03 PM

Answers

  • Actually it seems that wReserved2 is the byte size of the BLOB data, so that should be left as is.  I don't know what wReserved1 is, so perhaps it's best left alone?

    But the channel mask definitely needs to be fixed.  See the SPEAKER_FRONT_LEFT et al. definitions in ksmedia.h.  You may want 0x0033 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_BACK_LEFT | SPEAKER_BACK_RIGHT) or you may want 0x0107 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_FRONT_CENTER | SPEAKER_BACK_CENTER) depending on what kind of surround you're doing.

    Or you might try leaving the channel mask 0.
    Friday, April 25, 2008 5:08 PM
    Moderator

All replies

  • What string is in the registry when you manually set the default format via the GUI?
    Thursday, April 10, 2008 11:41 PM
    Moderator
  • There are 2 strings in the registry for my device that looks similar. In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\MMDevices\Audio\Render\_STRING_\Properties, here are the 2 keys and values.

     

    {f19f064d-082c-4e27-bc73-6882a1bb8e4c},0: 41,00,4f,74,28,00,00,00,fe,ff,04,00,40,1f,00,00,00,fa,00,00,08,00,10,00,16,00,10,00,00,00,00,00,01,00,00,00,00,00,10,00,80,00,00,aa,00,38,9b,71

    {e4870e26-3cc5-4cd2-ba46-ca0a9a70ed04},0: 41,00,4f,74,28,00,00,00,fe,ff,04,00,40,1f,00,00,00,f4,01,00,10,00,20,00,16,00,20,00,00,00,00,00,03,00,00,00,00,00,10,00,80,00,00,aa,00,38,9b,71

     

    Thanks for your help.

    Friday, April 11, 2008 6:00 PM
  •  

    Any idea if my problem is with the value of the PKEY_AudioEngine_OEMFormat that I use or if it is the way I call it using the KSCATEGORY_TOPOLOGY?

     

    Thanks

    Wednesday, April 16, 2008 2:06 PM
  • Matthew, did I give you the right info? I am really lost right now as to why this doesn't work. I tried many modifications to my inf and none of them work. I don't really know how I can debug this. I do see some keys in the registry added but when I plug my device the wrong audio format is still chosen by default and those values in the registry seem to have no effect. :-(

     

    Thanks

    Thursday, April 17, 2008 7:40 PM
  • Sorry for the delay in replying.  Looking at your initial format, I think the channel mask needs to be updated to contain four channels.  Here's the breakdown:

    41,00,8C,70,28,00,00,00,FE,FF,04,00,40,1F,00,00,00,FA,00,00,08,00,10,00,16,00,10,00,03,00,00,00,01,00,00,00,00,00,10,00,80,00,00,AA,00,38,9B,71

    This is a PropVariant of type VT_BLOB:

    vt 0x0041 // VT_BLOB
    wReserved1 0x708C - this should probably be 0
    wReserved2 0x0028 - so should this
    wReserved3 0x0000

    Here's the blob data, which is interpreted as a WAVEFORMATEXTENSIBLE:

    WAVEFORMATEXTENSIBLE
        WAVEFORMATEX
            wFormatTag 0xFFFE // WAVE_FORMAT_EXTENSIBLE
            nChannels 0x0004
            nSamplesPerSec 0x00001F40 // 8000
            nAvgBytesPerSec 0x0000FA00 // 64000
            nBlockAlign 0x0008
            wBitsPerSample 0x0010 // 16 bits
            cbSize 0x0016
        Samples.wValidBitsPerSample 0x0010 // all bits valid
        dwChannelMask 0x00000003 // stereo, but there are four channels!
        SubFormat {00000001-0000-0010-8000-00aa00389b71} // PCM

    Friday, April 25, 2008 4:57 PM
    Moderator
  • Actually it seems that wReserved2 is the byte size of the BLOB data, so that should be left as is.  I don't know what wReserved1 is, so perhaps it's best left alone?

    But the channel mask definitely needs to be fixed.  See the SPEAKER_FRONT_LEFT et al. definitions in ksmedia.h.  You may want 0x0033 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_BACK_LEFT | SPEAKER_BACK_RIGHT) or you may want 0x0107 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_FRONT_CENTER | SPEAKER_BACK_CENTER) depending on what kind of surround you're doing.

    Or you might try leaving the channel mask 0.
    Friday, April 25, 2008 5:08 PM
    Moderator
  • Thanks a lot for your help Matthew, I really really appreciate it!!!

     

    I managed to get a second USB audio device that we have here and that one supports 48kHz, 16-bit, Stereo (the format in the sysfx.inf example in the WDK). So I tried my inf file using that value (48kHz, 16-bit, Stereo) but the sound format was still set to 44kHz, 16-bit, Stereo. So my conclusion is that there is a problem with the way I set it with the KSCATEGORY_TOPOLOGY. So right now, what I am trying to do is simply set it to 48kHz, 16-bit, Stereo using the sysfx.inf example value.

     

    Again, I really appreciate your help Matthew, I talked to many people about this problem but no one was helpful as you are. Thanks.

    Monday, April 28, 2008 12:32 PM
  • Hi Matthew

     

    Thanks a lot for your help, I got it working.

    Monday, May 05, 2008 12:15 PM
  • JFC Dev, i got a problem, simalar to yours
    i need some help with an .inf file

    i got the standard TI PCM2902  but im only using as INPUT device
    i dont want it to become default playback (1 nothing is connected to it, 2 annoyance)
    and i need its format set to 16bit 2channel 44.1k

    i trying taking appart, wdm_audio.inf and i got lost

    could you share your .inf?

    would really save me :)

    thanks
    mitch
    Thursday, October 15, 2009 3:09 AM