[wdmaudiodev] custom multichannel devices in Vista

  • From: "Marc Titinger" <mtittinge@xxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Fri, 21 Jul 2006 18:46:37 +0200

Hi All,

We developed a wavepci miniport for a multichannel sound card. In WinXP, we could expose a Directsound device with 24 channels for instance, and have Media Player 10 play a wave file with 24 interlaced channels without problem. This worked in our case, because DirectSound called into the miniport?s DataRangeIntersection handler and retrieved in return the min between the actual device channels (24) and the channel count it requested (65536).

In Vista, this preliminary call into the DataRangeIntersection handler seems to be gone (with kmixer?) . Instead, it looks like the channel layout defined with mmsys.cpl is used, but the choice can be ?only? mono to 7.1.

I added a GET and SET support for KSPROPERTY_AUDIO_CHANNEL_CONFIG so that the KSAUDIO_SPEAKER_DIRECTOUT (zero) value can used with IDirectSound::SetSpeakerConfig, but a successful call to this method (and Format.nChannels = 24 ) still doesn?t prevent the stream to be created with the profile defined in mmsys.cpl.

Should?nt DirectSound keep asking for a datarange intersection when the application says ?this is a custom channel mapping? by setting IDirectSound::SetSpeakerConfig(0) ? Am I doing something wrong (besides using lots of channels ^^) ?

Thanks for your help,



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