This is unfortunately a known issue with the XP audio architecture. The only "workaround" (not really a good one) is to ensure that no audio is being captured or played back when AEC is instantiated. I realize this isn't a very satisfactory response. We are addressing this in the next major version of Windows. Martin Puryear Development Manager Microsoft Windows Audio/Video Devices Group This posting is provided "AS IS" with no warranties, and confers no rights. Ce message est fourni en l'état, sans garantie d'aucune sorte, et ne vous confère aucun droit. Vous assumez tous les risques liés à son utilisation. ________________________________ From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Korolev, AlexeyX Sent: Tuesday, July 22, 2003 7:45 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Issues with MS AEC. Hi, I'm writing full-duplex audio processing code. I've added MS AEC node to the driver stack. In most cases AEC is working fine. But, if user starts playing sound using Wave Out interfaces (for example using Windows Media Player) before our driver has inserted AEC to the driver stack, AEC doesn't work. I can't insert AEC node in topology when user-mode application is using Wave Out. Does anybody have information about it? Is there any known workaround for this problem? Thanks, Alexey