That's correct. The audio data received via the "loopback" interface is the output of the system mixer, which is what ultimately goes to the driver. The only exception would be in cases where certain content access controls are asserted by an application; it's possible for the loopback signal to have reduced fidelity in this case. However at this time I know of no application that does this. Frank Yerrace Microsoft This posting is provided "AS IS" with no warranties, and confers no rights. -----Original Message----- From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Roberts Sent: Thursday, January 07, 2010 9:03 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: PC Audio Capture Sushma wrote: > I had already tried as the described in the link you mentioned but the > audio capture was not satisfactory. The quality of sound was low. That suggests a misunderstanding or misconfiguration on your part. You should be getting the audio in its final form before it goes to the sound card. > So, i thought of going for a filter driver. I understand using > WaveIn/Wasapi API for Vista and Win 7. But my requirement is for Win > XP as well. > > For Win XP i need a filter driver to record the PC audio. Is this > correct? If so, at what level in audio stack i need this filter driver > to be present? Any info or samples would be much helpful. > One option is to use a virtual audio device, like the one here: http://software.muzychenko.net/eng/vac.html This creates a new audio device which applications can write to. The output of that virtual device is inside an application, which can do whatever it wants, including forwarding the audio on to real hardware. Pre-Vista, it is possible to insert an audio class upper filter to intercept the kernel streaming ioctls. It is surprisingly difficult in that situation to figure out what format the audio is in every case, so plan some frustrating test time. For WAVERT devices in Vista and later, this simply cannot be done. The audio engine in user-mode writes the data directly to the DMA buffer -- there are no kernel requests to intercept. -- Tim Roberts, timr@xxxxxxxxx Providenza & Boekelheide, Inc. ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/ ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/