[wdmaudiodev] help on starting driver project for usbaudio
- From: Cornelius Ihssen <cornelius.ihssen@xxxxxxxxxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Wed, 07 Mar 2007 18:03:14 +0100
Hi,
I'm new to this list and unfortunately new to windows driver
development, too. I'm trying to write some sort of driver for an
existing usb-audio-class compliant headset. Target platform is WinXP.
The behaviour of the headset should be altered for playback in 2 ways:
The (in fact) stereo output device should appear to the system as 5.1
multichannel device and in a second step I want to access the
multichannel PCM-data, do a downmix with some additional binaural
processing and send it out as stereo again.
After reading in Oney's book and some web research I see several
possibilities to do that, not willing to write my own AVStream/portcls
driver for usb from scratch:
- GFX Filter: I could do the processing easily there, but it's not
possible to mask the headphone as virtual 5.1 device and receive
multichannel streams -- same problem with a DirectShow filter. In
addition, GFX filters seem to be some sort of half baked (once
installed, you can't get rid of it...)
- Upper filter for usbaudio.sys: Currently I'm playing around with the
filter sample of oney's wdm book. I can trap all IOCTL_KS_PROPERTY and
hopefully dispatch them with KsDispatchSpecificProperty, but I don't
know yet which IRPs exactly ask for the KS topology of the device
object. Is it possible to overwrite them in a upper filter at all? Which
Requests describe the channel configuration, is it for example
KSAUDIO_SPEAKER_5POINT1?
- Lower filter for usbaudio.sys: I think it would also be possible to
attach a lower filter driver and intercept the URBs concerning the
device descriptors. But do I have access on the audio data in the
isochronous transfer at this point?
- Virtual 5.1 audio driver: My first approach was to start with one of
the MSVAD samples, do the processing there and create a handle on the
usb audio device for output.
There are probably even more solutions for my purpose. At the moment,
I'm sort of lost in it and don't know which way to go. What do you think
what's the most practicable approach? I'm glad for every hint and
suggestion...
Thanks in advance,
Cornelius
--
____________________________________
Cornelius Ihssen
sonic emotion ag
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