Re: possible audio buffer underrun & load balancing
Re: possible audio buffer underrun & load balancing
- Subject: Re: possible audio buffer underrun & load balancing
- From: Jeff Moore <email@hidden>
- Date: Thu, 27 Oct 2005 11:41:20 -0700
On Oct 27, 2005, at 10:25 AM, Khamba Staring wrote:
Is it normal that the processors can idle while the audiograph(s)
experience buffer underruns? Or is it the AltiVec units which are
loaded while the rest of the processor is idle?
Top and most other load measuring tools measure average load over
some duration of time. For real time work, what you need to be
concerned about is the peak load. It is the moments of peak load that
cause your engine to miss the real time deadline and drop samples on
the floor.
Can I measure any of this?
Of course. HALLab's IO cycle telemetry provides a HAL's eye view of
what's going on. Plus, you have Shark and other system performance
measuring tools. Finally, you can always put your own instrumentation
in your code to to measure how much time you are using.
And are there callbacks in an AUGraph which are called when buffer
underruns are detected?
The HAL issues kAudioDeviceProcessorOverload notifications when it
detects that a process has missed a deadline.
--
Jeff Moore
Core Audio
Apple
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