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Re: AU question: asynchroneous pulling
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Re: AU question: asynchroneous pulling


  • Subject: Re: AU question: asynchroneous pulling
  • From: Thorsten Karrer <email@hidden>
  • Date: Tue, 19 Oct 2004 21:05:23 +0200

Hello!


Thanks for your help! But I have still some questions left.

Am 19.10.2004 um 20:23 schrieb William Stewart:
You can't do it this way.
The intention of I/O is that it is synchronous - each request someone makes
for output, you get the input required for that....
So - for an effect this means *always* that a host pulls you for 512 frames,
and you ask for 512 frames of input. The reason this is this way is that we
treat effect types of AU as something that operates in "real-time" - so you
can't just asynchronously ask for input - if its real-time the input isn't
there!

Hmm...I thought that is the way the Varispeed AU is working. From my understanding it must pull it's input for a different amount of samples than the host pulls the output of the Varispeed.
I did declare my AU as an "aufc", so I thought I would be able to do that kind of stuff.


Problem2:
Thread1 has to pull a lot of samples at one time, since my effect is
based on a FFT of size 4k. Usually the input is not able to provide
such a large chunk of samples so I decided to split up the pulls into
pieces of length of the number stored in the MaxFrames property of the
input...

You use your max frames for this - we assume that a host will generally set
max frames consistently between different audio units, so its a reasonable
assumption that your input's max frames is the same as yours. You can also
have input coming from a callback, so you can't get max frames in that case.

Ok, I tried to get my max frames using the code snippet below:

UInt32 MaxFrames;
result = GetProperty(kAudioUnitProperty_MaximumFramesPerSlice,
				kAudioUnitScope_Global,
				0,
				&MaxFrames);

But all I get is  result == kAudioUnitErr_InvalidProperty


Thanks again for helping!

Best regards,

	Thorsten


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