[wdmaudiodev] Re: AVStream virtual mic: why could external application 'reset' volume level to 100%?

  • From: "Matthew van Eerde" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "Matthew.van.Eerde" for DMARC)
  • To: Alexander Ivash <elderorb@xxxxxxxxx>, "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Thu, 11 Aug 2016 22:19:59 +0000

Windows offers an API to applications to change the endpoint volume.



If the driver offers a KSPROPERTY_AUDIO_VOLUMELEVEL node, the API will be 
connected to this node.



If the driver does not, Windows will insert a software volume APO.



https://msdn.microsoft.com/en-us/library/windows/hardware/ff536251(v=vs.85).aspx



From: Alexander Ivash<mailto:elderorb@xxxxxxxxx>
Sent: Thursday, August 11, 2016 3:18 PM
To: wdmaudiodev@xxxxxxxxxxxxx<mailto:wdmaudiodev@xxxxxxxxxxxxx>
Subject: [wdmaudiodev] AVStream virtual mic: why could external application 
'reset' volume level to 100%?



For some reasons it happens with virtual mic, but everything looks
fine with real one, what could be the difference?

Another observation, real mic's volume level changes from "+40dB" to
"+60dB" in Win10, while virtual mic changes from "0" to "100". Is it
because I didn't specify 'volume' node in topology or something like
this?

Regards, Alexander
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