Port driver

NTDEV
1

hi
I read in the following MSDN documentation that portcls driver does not support external buses such as USB .

http://msdn.microsoft.com/en-us/library/windows/hardware/ff536829(v=vs.85).aspx

But when i connected my audio device in windows 7 system , it loads the default driver and audio playback is working fine. But when i saw the driver properties it is showing the following drivers loaded
USBAudio.sys , portcls.sys,KS.sys,sysfx.dll and wmalfxgfxdsp.dll

  1. The quesion is how come the portcls driver is getting loaded for USB device :frowning: …
  2. What is the use of wmalfxgfxdsp.dll ?
2

xxxxx@gmail.com wrote:

But when i connected my audio device in windows 7 system , it loads the default driver and audio playback is working fine. But when i saw the driver properties it is showing the following drivers loaded
USBAudio.sys , portcls.sys,KS.sys,sysfx.dll and wmalfxgfxdsp.dll

  1. The quesion is how come the portcls driver is getting loaded for USB device :frowning: …

Implementation detail. USBAudio.sys is an AVStream driver (hence
KS.sys). KS.sys is probably not a port-class driver, but it uses some
of the capabilities that portcls.sys provides.

  1. What is the use of wmalfxgfxdsp.dll ?

It provides some kind of a connection to the local effects (“lfx”) and
global effects (“gfx”) audio processing objects that are part of the
Vista-and-beyond audio stack.

–
Tim Roberts, xxxxx@probo.com
Providenza & Boekelheide, Inc.

3

I have question regarding audio architecture , ie, Which driver or component in windows detects the external audio devices like headset/usb headset/bluetooth insertion and does autorouting ?
Does it perform any specific algorithm to decide to which it should route the audio?