[wdmaudiodev] Re: Shared mode recording doesn't work if CurrentCount is nonzero

  • From: Matthew van Eerde <Matthew.van.Eerde@xxxxxxxxxxxxx>
  • To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Mon, 25 Aug 2014 15:32:31 +0000

Well, one way to avoid the problem reliably is for all DirectKS clients to 
check CurrentCount when opening a pin. This is the strategy that is currently 
adopted by the audio engine.

Whether it is a good strategy or not (and whether the game is worth the candle) 
is open to discussion.

-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Eugene Muzychenko
Sent: Sunday, August 24, 2014 5:44 AM
To: Matthew van Eerde
Subject: [wdmaudiodev] Re: Shared mode recording doesn't work if CurrentCount 
is nonzero

Hello Matthew,

> A direct KS client sets the mux to "microphone" and captures from the 
> streaming endpoint. The current instance count goes from 0 to 1.

> Now an app tries to capture from the line in. The Windows audio engine 
> would normally set the mux to "line in" and open a pin instance on the 
> streaming pin. This would cause the Direct KS client to mysteriously 
> start capturing data from the line in as well, which would be 
> undesired.

Exactly the same would happen if Audio Engine starts capturing first, supposing 
all is OK then another KS client changes mux settings.

Such problems cannot be avoided reliably so everybody who uses Direct KS 
clients must take care about that.

Regards,
Eugene

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