Jeff, Even if using push mode, wouldn't the timer interrupt be running for each streaming device? Doesn't the timer interrupt act just like a hardware interrupt with regard to the CPU state? Having written drivers for radio station automation systems in the past, having any glitches in the audio would be a problem for station running 24/7. Pull mode does give a more 'hardwired' connection between the hardware position and the software streaming engine. It just makes me 'feel better' to know that the hardware is controlling the position instead of the software guessing. Is ASIO an option? That would give a single hardware interrupt at the bufferSwitch point for all the channels and bypasses everything Microsoft so you don't have to worry about a system sound from an error dialog box interrupting the on-air audio. No worrying about something in the streaming engine resampling the audio or having to worry about the two extra limiters that are put into the audio stream whether you want them or not. Exclusive mode fixes most of that... :-) OK, I admit that I am an ASIO evangelist. Thank you, David A. Hoatson Lynx Studio Technology, Inc. www.lynxstudio.com -----Original Message----- From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jeff Pages Sent: Tuesday, November 16, 2010 4:25 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Pull mode versus push mode We make a range of AM, FM and DAB+ radio capture cards, which create a Windows audio capture device for each station received. Typically each card can create up to 32 such audio capture devices. While everyone is extolling the virtues of supporting pull mode on Windows 7, I'm wondering if, in this situation, push mode might be preferable. On a machine fitted with an AM, FM and three DAB+ cards (a fairly typical configuration here), if they were operating in pull mode each station would be generating its own interrupt at a 10ms rate, creating the potential of 160 interrupts every 10ms, each queuing DPCs to trigger notification events. Contrast this to push mode, where presumably a single system timer interrupt causes each audio engine instance to just poll its corresponding position register. Audio latency is irrelevant in this application, so my gut feeling is that supporting pull mode would create more problems than it solves. I'd be curious to hear what others on this list think, though. Jeff