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Re: ProductID read from the USB descriptors for an audio device
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Re: ProductID read from the USB descriptors for an audio device


  • Subject: Re: ProductID read from the USB descriptors for an audio device
  • From: Herbie Robinson <email@hidden>
  • Date: Wed, 5 Jul 2006 22:24:28 -0400

If he scans the IO Registry, he can get the information he wants -- reading that information isn't locked when a driver has it open (it might even be cached in the registry). Changing anything when another driver has it open will be blocked. Don't know how the device would get correlated back to the AudioDevice, though. If that doesn't matter, the sample MIDI driver has a decent example of how to walk the IO Registry database looking for a particular kind of USB device.

At 12:28 PM -0700 7/5/06, Jeff Moore wrote:
No this is not possible. We purposefully abstract this info away in the driver model. I'm curious about what you need this info for?

If you absolutely must know it, then you are pretty much on your own for discovering it. The HAL gets it's info about the device from the IORegistry, so your best bet is to go the same route. However, if the info you need requires doing IO with the device, you may be out of luck since the device is already matched to a driver in the kernel which will (I think) prevent you from accessing it directly out in user space.

On Jun 29, 2006, at 5:38 AM, Alex Ivanov wrote:

Ok thanks, but my problem is that i need to obtain
that USB productID through an AudioDeviceID. Is this
possible using CoreAudio API?

This is more a question for the USB dev list (
email@hidden ) :)

You can find answers to that question by looking at
the /Developer/
Examples/IOKit/usb/ folder. The "RawDeviceAdded"
function in ezloader/
main.c contains code to do that

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References: 
 >Re: ProductID read from the USB descriptors for an audio device (From: Jeff Moore <email@hidden>)

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