Re: wdm streaming capture audio devices

On 17 Mar 2006 02:28:30 -0800, MoonStorm wrote:

I am trying to figure out the use of some input/output pins on an audio
capture filter located in "wdm streaming capture devices" with no luck
so far.

The device is called "SoundMax Digital Audio" with the following pins:
- input: DAC, ADC
- output: DAC, Recording Control

Has anyone encounter these? ... or even use them?

What you are doing here, effectively is accessing the device at device
driver level.

In fact (I think) this is a bit below the top of teh device stack.

YOu would ONLY access these devices if you wanted to bypass the DIrectSound
mixing and so on and take exclusive control of the device. Pretty much the
only sane reason for doing so is if you want the latency below the 20 -30
mS which DirectSound adds.

Even then there is probably a similarly named device which is a level
higher and has real input and output pins.

The documentation for this are is in the Device Drivers Kit and it makes
the normal DirectShow documentation look like a kindergarten text on cats
and dogs.

If you REALLY need to play with this stuff for latency reasons, gird your
loins! If you do NOT, run. Run fast and far!

Iain Downs (DirectShow MVP)
Commercial Software Therapist