Microphone Virtual Driver

NTDEV
1

Hi all,

I need to write a virtual driver which acts like a microphone.
Something like daemon tools, but which provides a virtual
microphone.

This is for providing interactive-input to an application
which uses audio input (I don’t have any control
over the program & don’t have it’s source code), and provides
a selector for which device to use for input. So if my
driver appears in the list, I can get input from it.

What sort of driver must I write?
How do I tell windows that the hardware is present when it is
actually not? Is it possible to load the driver before running
the application & unload it after the app exits?
Also, any idea how this driver can be loaded into a Terminal
Services session?

My platform is Windows 2000 and above. I am a newbie to
driver development but have read some of the
DDK material.

Any suggestions/hints/links will be much appreciated!

Thanks in advance,

  • Shree Kumar
2

Shree Kumar wrote:

I need to write a virtual driver which acts like a microphone.
Something like daemon tools, but which provides a virtual
microphone.

I’d suggest that you first investigate writing a user-mode DirectShow
“capture” filter. You’ll eventually need to write some sort of applet
that will create a filter graph including your target application,
though. If you need your audio source to be available by default, you
will need to write some sort of WDM filter (*not* a kernel streaming
filter), which is extremely hard to do in this space. Thus, if the
DirectShow routine doesn’t pan out, you would really need to hire an
expert consultant to do the job for you.

–
Walter Oney, Consulting and Training
Basic and Advanced Driver Programming Seminars
Check out our schedule at http://www.oneysoft.com

3

Hi,

Thanks, Walter. Turns out that there is a msvad sample
which has a virtual autio output driver, among other
things.

I compiled and loaded the “simple” driver from msvad.
I installed the driver on windows server 2003. When
I log in locally, I can see and use the device.
However, when I login to a terminal server session,
I can’t see the device! Any idea what is going on???

Regards,

Shree Kumar

Walter Oney wrote:

Shree Kumar wrote:
> I need to write a virtual driver which acts like a microphone.
> Something like daemon tools, but which provides a virtual
> microphone.

I’d suggest that you first investigate writing a user-mode DirectShow
“capture” filter. You’ll eventually need to write some sort of applet
that will create a filter graph including your target application,
though. If you need your audio source to be available by default, you
will need to write some sort of WDM filter (*not* a kernel streaming
filter), which is extremely hard to do in this space. Thus, if the
DirectShow routine doesn’t pan out, you would really need to hire an
expert consultant to do the job for you.

–
Walter Oney, Consulting and Training
Basic and Advanced Driver Programming Seminars
Check out our schedule at http://www.oneysoft.com

Questions? First check the Kernel Driver FAQ at http://www.osronline.com/article.cfm?id=256

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