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Re: Audio Unit synth how-to
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Re: Audio Unit synth how-to


  • Subject: Re: Audio Unit synth how-to
  • From: William Stewart <email@hidden>
  • Date: Tue, 10 May 2005 11:09:19 -0700


You have to understand that the host basically controls your behaviour. It calls Render, not you. The host may "take you offline" in this case - ie. not call your Render call, or it may not - and just pump silence through. You don't know (nor do you care) _ you just have to respond to what the host asks you to do.


Have a look through the documentation we do have:

/Developer/Examples/CoreAudio/Documentation

There's some comments there about the general rendering process from the host's perspective, and how AudioUnitReset ties into that process as well.

Never mind, I found the answer - set the
kAudioUnitRenderAction_OutputIsSilence flag.

Not really. You set this flag ***whenever*** you are returning a buffer that is completely silent.


This need have nothing to do with whether the user has "hit the stop button" or not. For instance, a synth maybe silent for a large part of a song because there's no notes being played by it - but the song is still playing.

Bill

On 10/05/2005, at 9:47 AM, h wrote:

Here's an easy one: Once the user has hit the stop button, how do I
signal to the audio unit host to stop calling my Render() function?
If this is all documented somewhere, please let me know.

Cheers,
Hamish

--- James McCartney <email@hidden> wrote:


On May 8, 2005, at 2:59 PM, h wrote:


I just want to check - given that I have to call GetParameter()

during

Render() - I take it that if the parameter cannot change partway
through my Render() call? (Or else some kind of mutex would be
needed)?




Since setting a 32 bit word (e.g. a 32 bit float) is atomic, no mutex

is needed.
The value of GetParameter could change midway. It isn't likely to
change on a single processor because of the priority of the render
thread, but it may happen on a dual processor.

--- james mccartney --- apple coreaudio





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 >Re: Audio Unit synth how-to (From: h <email@hidden>)

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