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Re: performAudioEngineStart vs. startAudioEngine

The headerdoc for startAudioEngine() is incorrect (as is that for stopAudioEngine() as well) - you can ignore what it says. The correct function to override is performAudioEngineStart() as you have done. The function startAudioEngine() is called by the family when the HAL needs to start doing I/O. It manages the internal state and calls performAudioEngineStart() to actually deal with the hardware.

More (correct) information is available in the online documentation in /Developer/Documentation/Darwin/IOKit/DeviceDrviers/WritingAudioDrivers.

I've filed a Radar to have the headerdoc fixed.

- Eric

On Thursday, December 19, 2002, at 05:15 AM, Michael George wrote:

I am a bit confused about implementing a subclass of an IOAudioEngine...

According to the sample code, my subclass should define performAudioEngineStart(), a virtual method, which will be called when the audio engine is supposed to start.

However, in the online HTML docs, there is no mention of performAudioEngineStart() (though it *is* in the header), but there *is* startAudioEngine() (in the headers *and* the docs). And in the description of startAudioEngine() it says that it "must be overridden by subclass" and that _setState(kAudioEngineRunning) must be called...

Currently, I have a mostly-working driver that uses performAudioEngineStart() but not startAudioEngine(), so apparently the latter is not necessary, though the docs say it is...

Can anyone direct me to some clarification of what's going on here?

Thanks!


-Michael
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References: 
 >performAudioEngineStart vs. startAudioEngine (From: Michael George <email@hidden>)



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