Thank you Frank for this input. By the way do you see any limit's for the number of channels of a multichannel device ? 32 channels, as the WAVEFORMATEXTENSIBLE's dwChannelMask is a DWORD ? Or is it possible to handle more channels ? The reason for my question is that we are working on a 64 channel sound card. Markus. -----Message d'origine----- De : wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx]De la part de Frank Yerrace Envoyé : mercredi 22 mars 2006 23:03 À : wdmaudiodev@xxxxxxxxxxxxx Objet : [wdmaudiodev] Re: My first WASAPI implementation. > We do it in order to support legacy apps that don't support multichannel > hardware. The API layers do this on your behalf. For example, the application can open stereo formats using waveOut regardless of how many channels the actual audio hardware has. The stereo data ends up being directed to the two output channels identified as front-left and front-right. > Plus, it lets you address different sets of inputs and outputs with multiple > applications simultaneously, which is useful. If the user wishes to configure his device installation to have two channels going to one set of speakers and other channels going to other sets of speakers, then it is appropriate for the device to be presented as several completely independent sets of outputs. What Vista currently does not promote is a hybrid between these two configurations, allowing apps to discover for example 4 stereo devices *and* one 8 channel device. At this time, we don't understand how this is a useful feature going forward. I'd like to understand more about this sort of usage if others feel this is a problem. Frank Yerrace Microsoft Corporation This posting is provided "AS IS" with no warranties, and confers no rights. _____ From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Matt Gonzalez Sent: Wednesday, March 22, 2006 1:13 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: My first WASAPI implementation. We do it in order to support legacy apps that don't support multichannel hardware. Plus, it lets you address different sets of inputs and outputs with multiple applications simultaneously, which is useful. Matt wdmaudiodev-bounce@xxxxxxxxxxxxx wrote: I never really did understand why vendors would publish a bunch of stereo pairs rather than one device that had many channels. Was this to support legacy OS's that didn't have WAVEFORMATEXTENSIBLE? If I have one 8-channel stream I want to output, the last thing I want to do is open 4 virtual stereo devices and issues the play command to each one. Chris Perry Bose Corporation -----Original Message----- From: wdmaudiodev-bounce@xxxxxxxxxxxxx [ mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Frank Yerrace Sent: Wednesday, March 22, 2006 3:36 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: My first WASAPI implementation. my biggest gripe currently is not knowing if its possible for a device manufacturer to define a huge 16 output (or more) endpoint in one IAudioClient without having to fake it with WAVEFORMATEXTENSIBLE's nChannels set to 16 and dwChannelMask set to 0x00, or to have that manufacturer define a bunch of separate stereo pairs to do the job. Can you clarify what you would *like* to see here? At this time, we feel that if the hardware is intended to be used as a 16-channel output, then it should be presented as a single 16-channel output accessed through a single instance of IAudioRenderClient using a 16-channel WAVEFORMATEXTENSIBLE. Frank Yerrace Microsoft Corporation 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 David Viens Sent: Wednesday, March 22, 2006 12:17 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: My first WASAPI implementation. Ron Kuper wrote: David, were the "suprises" pleasant or unpleasant? Ha, of course I meant "surprisingly good" results, with little to no clicking (but sometimes occurring with even moderate DSP cpu loads) I ran the code with my onboard NVidia AMD nforce4 ac97, a Roland ua-1a device running "USB composite device", and my Terratec EWS88MT's extra output (fixed at 48 Khz) - not the full 12/10 combo which doesnt appear. cant try my various SB cards, because of lack of working drivers. I'm trying to put latency down, but i got tired of shooting in the dark with trying things. Thats why i'm awaiting answers before continuing. Knowing that vista is now scheduled to release in 2007, its not that urgent it would seem. The way it currently works is a bit odd, with the 100-nano second "periods" settings, which cant seem to fit on even sample frames in some circumstances, or .. sigh allow for power of two sized buffers. Also since no pro audio card has Vista drivers yet, my biggest gripe currently is not knowing if its possible for a device manufacturer to define a huge 16 output (or more) endpoint in one IAudioClient without having to fake it with WAVEFORMATEXTENSIBLE's nChannels set to 16 and dwChannelMask set to 0x00, or to have that manufacturer define a bunch of separate stereo pairs to do the job. (i never implemented WDM-KS's pin querrying stuff mind you - so might be a similar thing) I've got another bag of questions... ****************** 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/ You can find Digigram at: Prolight+Sound, Frankfurt, Germany, Mar 29 - Apr 1, 2006, Hall 8, Booth n° D34