[wdmaudiodev] Re: Finding and Locking USB Audio Device from Applications

  • From: Mark Miller <marklosangeles2003@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Sat, 1 Nov 2003 16:45:19 -0800 (PST)

Thanks for the reply Daniel.  

I forget to ask in my original post what is the sequence of commands to find 
the USB audio device programmatically?  With the HID interface, you can ask for 
the HID GUID by the command HidD_GetHidGuid(), then call SetupDiGetClassDevs() 
with the HidGuid value to get the DeviceInfoSet, which gets you further down 
the chain to loop through the HID devices to match the Vendor/Product IDs in 
order to find the handle to the HID device and finally open it with 
CreateFile().  I am sure there must a similar sequence for usbaudio.sys 
devices. I would like to be able to the find the audio interfaces by 
Vendor/Product ID numbers.  MSDN and other references (so far) have not pointed 
me in the proper direction or at least I don't know how to ask for it. ;)

In response to not being able to unselect the usb device as the "preferred" 
audio device, couldn't a combination of an .inf file and an upper or lower 
filter driver force this action?  Following up my original post, couldn't I 
open the handle  --after I learn how to find it -- to my usb audio device as 
"not shared" and force the system and other applications to use the other audio 
devices?  I plan on having my device's Windows application load on startup and 
stay in the system tray.  As a matter of fact, I would like it if the device is 
plugged in and the application is not running, that the application is 
automatically launched.  My USB digital still camera does that.  I can tell it 
to launch Photoshop or other graphics application to receive the photos every 
time the camera enumerates. Can something like that be done through filters or 
some other user-level application, or am I looking at custom audio drivers for 

I know the raison d'etre for this mailing list is to develop WDM audio drivers, 
I would prefer be able to use the usbaudio.sys driver as much as possible with 
this device.  



From: "Daniel E. Germann" 
Subject: [wdmaudiodev] Re: Finding and Locking USB Audio Device from Applicatio
Date: Fri, 31 Oct 2003 08:07:06 -0600

Hi, Mark.

I don't think there's a way to prevent a device from becoming the preferred
audio device. Take a look at this message thread in the wdmaudiodev


----- Original Message -----
> Date: Wed, 29 Oct 2003 16:38:59 -0800 (PST)
> From: Mark Miller 
> Subject: [wdmaudiodev] Finding and Locking USB Audio Device from
> Hopefully this post isn't too basic or off-topic for this mailing list.
> I have developed a composite HID / audio USB device. It enumerates
successfully and works. I am using the usbaudio.sys and hidusb.sys class
drivers and do not have any .inf files or overtly made any registry
additions or modifications for this device.
> But it becomes the preferred audio device and all audio goes through it.
I want my application to use the device exclusively and leave the preferred
audio device settings as the were before this USB device was plugged in.
Also, I don't want this device to show up as a choice in the mixer at all.
> Is there a simple sequence of code to do this or do I need to read scads
of information to figure it out?
> Any push towards a book, website, msdn location, etc. would be appreciated
if it cannot be answered easily in this mailing list.
> Thanks,
> Mark


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