Re: GenericOutput AU -- what is it?
Re: GenericOutput AU -- what is it?
- Subject: Re: GenericOutput AU -- what is it?
- From: Bill Stewart <email@hidden>
- Date: Wed, 23 Oct 2002 12:40:51 -0700
on 19/10/02 6:27 PM, Kurt Revis wrote:
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AUComponent.h lists this component:
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kAudioUnitSubType_GenericOutput = FOUR_CHAR_CODE('genr'),
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What is it for, and how does it differ from the HALOutput AU? I don't
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see it mentioned anywhere else in the headers, documentation, examples,
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or the mailing list archives. Is it just a base class that is
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underneath HALOutput?
Basically:
AUBase->AUConverter->GenericOutput->HALOutput
The Generic output would be used in a couple of situations..
AUGraphs need an output node to start/stop - so if you're not outputting to
a device, then you need a generic output unit to use. (Say you're saving to
a file, or you have a secondary render thread, or you represent each channel
in a mixer with a sub-graph, etc...
How is it useful?
There is a property _IsRunning... When the generic unit gets started or
stopped, this property value changes and you get a notification.
The Generic output unit does NOT have a thread or driving code - unlike a
HAL output unit for instance, which is driven by the device.
So, you can use the notification to then start your "Get Audio Data" thread
- which then turns around, calls the output unit's AudioUnitRender call then
does whatever its going to do with the generated data...
(Of course, in the subgraph case, the generic output is just the bridge that
the parent graph uses to call into the subgraph )
Bill
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Just curious...
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--
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Kurt Revis
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email@hidden
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