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Re: Virtual audio device glitches
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Re: Virtual audio device glitches


  • Subject: Re: Virtual audio device glitches
  • From: Robert Bielik <email@hidden>
  • Date: Thu, 14 Oct 2010 08:52:32 +0200

Robert Bielik skrev 2010-10-14 07:53:
Jeff Moore skrev 2010-10-13 20:53:
My first suspicion is that this is about the erase head running too fast. A quick and dirty way to check for this would be to turn the erase head off using IOAudioEngine::setRunEraseHead() in your driver.

If this turns out to be the case, you'll want to take a look at how you have implemented IOAudioEngine::getCurrentSampleFrame() as this method controls. This is the method that controls the erase head's concept of time. You might want to take a look at the AudioReflectorDriver sample for an example of a driver implementing IOAudioEngine::getCurrentSampleFrame() to keep the erase head out of the way of things.

Thnx Jeff, I tried it out, but no change.. still there are pops/clicks every second. Problem is that since my approach is two tiered and my application resets the driver when I start the streaming, I don't know if its a problem in the driver, or in my streaming application :(


A question regarding timestamp, what is the unit of the timestamps given to takeTimeStamp ? Is in nanosecs ?

If so, would this work:

mach_timebase_info tbi;
clock_timebase_info(&tbi);
uint64_t time;
clock_get_uptime(&time);
time -= mStartTime;
time *= tbi.numer;
time /= tbi.denom;
AbsoluteTime absTime = *((AbsoluteTime*)&time);

engine->takeTimeStamp(true, &absTime);

??
TIA
/Rob
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  • Follow-Ups:
    • Re: Virtual audio device glitches
      • From: Jeff Moore <email@hidden>
References: 
 >Virtual audio device glitches (From: Robert Bielik <email@hidden>)
 >Re: Virtual audio device glitches (From: Jeff Moore <email@hidden>)
 >Re: Virtual audio device glitches (From: Robert Bielik <email@hidden>)

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