[wdmaudiodev] Re: Problem using multimedia timers

  • From: timr@xxxxxxxxx
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Sun, 31 May 2009 21:58:13 -0700

On Sun, May 31, 2009 at 05:40:35PM -0400, Lokesh Patakolusu wrote:
> I am trying to use multimedia timers for audio synchronization.I am trying
> to get
> event every 20 ms so that i can fill up the audio buffer for the driver
> to play.I wrote a  test app to see how the multimedia timers work.I am
> trying to
> print the time intervals . when i start other applications on vista
> the timing interval gets affected.It shows 26, 45 ms etc even though it is
> set to 20ms.
> Pls let me know why its happening so if anybody have idea.

Sure -- it's because Windows is not a real-time operating system.  There
are no latency guarantees.

> Can we depend on multimedia timers for the events for the audio 
> applications.

Did you use timeBeginPeriod to set the timer resolution down?  The 
downside of that approach is that it uses more CPU.
Tim Roberts, timr@xxxxxxxxx
Providenza & Boeklheide, Inc.

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