[wdmaudiodev] Re: Race to set record sampling rate on KMixer / KS pin / soundcard

  • From: "Jeff Pages" <barefeet@xxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Thu, 4 Mar 2010 06:49:51 +1100
I am faced with a situation where my users must use two independent software 
applications throughout the day: the first application (a phone) records
audio at 8kHz and the second application (an automatic transcriber) records audio at 16kHz. I am an engineer responsible for working on the transcriber 
application.

My problem is that if my users launch the phone first, Windows initializes
the sound system to a sampling rate of 8kHz.  When the users subsequently
launch the transcriber, the transcriber requests 16kHz audio from the sound 
system.  The sound system provides a 16kHz audio stream, but it is really
8kHz audio resampled by KMixer to 16kHz.  This results in an unacceptable
loss of audio quality.

I need to find a way to programmatically detect this situation.  Upon
detection I would warn the user and provide problem resolution
instructions.  Something like "please launch transcriber first, phone
second."
My suggestion would be to write a service that opens the audio input at 16kHz. This will always start before either application.
Of course the other solution is to migrate to Windows 7 (or Vista) where the hardware rate is set by the audio engine settings, not the first application to open the device. 

Jeff

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