[wdmaudiodev] Re: USB audio descriptor question
- From: Tim Roberts <timr@xxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Mon, 18 Feb 2008 09:44:13 -0800
Uwe Kirst wrote:
Hello,
I want to develop an USB audio device and I'm new with this stuff. So
far I did only PCI and Firewire devices.
My question is about the descriptors: It seems to be possible that a
devices is detected and Windows shows up the vendor and product
information without loading a driver or looking at a special .inf
file. I assume this is done by a special descriptor within the device.
At first I thougth this is done by the vendor information in the
device descriptor: There is a string index which may point at a vendor
and product string. But it seems that windows ignores this string
information.
Does anyone know how this works?
Is this issue related to the MODs (Microsoft OS descriptors)?
No, this is all driven by the device class in the device descriptor.
Microsoft has drivers for most of the standard USB device classes (HID,
Audio, Video, Printer, Scanner, Storage, etc.). A USB storage device
has the storage device class in its device descriptor. Windows will
first search for a specific match based on VID, PID, and Revision; then
it looks for VID and PID; then it looks for device class.
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
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