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Re: AudioUnitRender

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Re: AudioUnitRender

Subject: Re: AudioUnitRender
From: William Stewart <email@hidden>
Date: Fri, 26 Oct 2007 19:15:04 -0700

You should not initialise the other AU until you are initialised.

when you call the other AU's AU Render call you need to have a callback function to provide input for it - and you have to get the input for your surrounding AU too. So, have a look at the AUEffectBase::Render call and follow the input element's path to getting the input

But, really I have to ask the inevitable question - why are you writing an AU to host another AU? Why not just connect that AU to the one you are writing (MyAU)

Bill

On Oct 26, 2007, at 1:14 PM, email@hidden wrote:

Hey,
I'm trying to create an audio unit which calls another audio unit and I'm not "getting" something I'm reading in the documentation.

AU's are based on a pull model, so is there an accepted way to "push" data through an AU? In the sample code below I've sucessfully instantiated and initialized the AUPitch component and now I'd like the AU to Process data inline.
I must be missing something obvious.....
->Ken
************************************************
#include "MyAU.h"
#include <AudioToolbox/AudioToolbox.h>
struct AudioUnitRenderGluePB {
	unsigned char                  componentFlags;
	unsigned char                  componentParamSize;
	short                          componentWhat;
	AudioBufferList*               ioData;
	UInt32                         inNumberFrames;
	UInt32                         inOutputBusNumber;
	const AudioTimeStamp*          inTimeStamp;
	AudioUnitRenderActionFlags*    ioActionFlags;
	AudioUnit                      ci;
};
// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
COMPONENT_ENTRY(MyAU)
ComponentInstance				MyAU::softWhammy_ = NULL;
Component						MyAU::softWhammyComponent_ = NULL;
AudioTimeStamp*					MyAU::theTimeStamp_ = NULL;
AudioUnitRenderActionFlags*		MyAU::ioActionFlags_;
// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // MyAU::MyAU // ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ MyAU::MyAU(AudioUnit component) : AUEffectBase(component) { ComponentDescription softWhammy = { kAudioUnitType_Effect, kAudioUnitSubType_TimePitch, kAudioUnitManufacturer_Apple, 0, 0};
	CreateElements();
	Globals()->UseIndexedParameters(kNumberOfParameters);
	SetParameter(kParam_One, kDefaultValue_ParamOne );
	softWhammyComponent_ = FindNextComponent(NULL,&softWhammy);
	softWhammy_ = OpenComponent(softWhammyComponent_);
	ComponentResult result = AudioUnitInitialize( softWhammy_);


#if AU_DEBUG_DISPATCHER
	mDebugDispatcher = new AUDebugDispatcher (this);
#endif

}
ComponentResult MyAU::ComponentEntryDispatch(ComponentParameters *params, AUBase *This) {

ComponentResult result = noErr; switch (params->what) { case kAudioUnitRenderSelect : { AudioUnitRenderGluePB *theParams = (AudioUnitRenderGluePB *)params; theTimeStamp_ = (AudioTimeStamp*)theParams->inTimeStamp; ioActionFlags_ = (AudioUnitRenderActionFlags*)theParams- >ioActionFlags; } } result = AUEffectBase::ComponentEntryDispatch(params, This); return result;
}
// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // MyAU::MyAUKernel::Process // ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ void MyAU::MyAUKernel::Process( const Float32 *inSourceP, Float32 *inDestP, UInt32 inFramesToProcess, UInt32 inNumChannels, // for version 2 AudioUnits inNumChannels is always 1 bool &ioSilence ) {

AudioBuffer theBuffer = { inNumChannels, inFramesToProcess * sizeof(Float32), inDestP }; AudioBufferList theList = { 0 }; theList.mNumberBuffers = 1; theList.mBuffers[0] = theBuffer;
	ComponentResult result =
             AudioUnitRender(
				softWhammy_,
				ioActionFlags_,
				(const AudioTimeStamp*)	theTimeStamp_,
				0,
				inFramesToProcess,
				&theList);
}
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