[wdmaudiodev] Msvad pcmex, audio channel mask

  • From: Kim Therkelsen <kim_t26@xxxxxxxxxxx>
  • To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Sun, 3 Feb 2013 15:10:23 +0000

I have made an implementation based on the msvad pcmex example that downmixes 
from 1-8 audio channels to 2 channels.
In pcmex.h MIN_CHANNELS is set to 1 and MAX_CHANNELS_PCM to 8. After installing 
the driver on Win7, I have set the loudspeaker setup to 7.1. Now when I 
playback some stereo, 5.1 or 7.1 audio material the driver always receives 8 
audio channels in CMiniportWaveCyclicStreamMSVAD::Init (pWfx->nChannels=8), and 
the channel mask received in CMiniportWaveCyclic::ValidateFormat
is always 0x63f (the standard 7.1 setup). The behaviour I need is stereo->2 
channels, 5.1->6 channels, and 7.1->8 channels. Actually I need to know the 
original format (the channel mask) of the audio material inside the driver so I 
can perform a proper downmix.
How do I acquire the needed information about the audio material?
Best regards,

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