RE: Using an AU directly
RE: Using an AU directly
- Subject: RE: Using an AU directly
- From: Darrell Gibson <email@hidden>
- Date: Mon, 7 Sep 2009 11:07:12 +0100
- Acceptlanguage: en-US, en-GB
- Thread-topic: Using an AU directly
Jean-Daniel,
Thanks for your reply. I had not thought of just calling the AudioUnitRender() when I want to process data. However, I still want the AUs operation to be performed real-time. My current understanding is that a render callback will be executed by a separate thread. Surely if I just call the AudioUnitRender() in a loop from the current thread I'm like to run into potential timing/breakup issues?
I still want the AU to process data in a normal realtime manner. I just don't want to have an output.
Thanks for your help.
Darrell.
________________________________________
From: Jean-Daniel Dupas [email@hidden]
Sent: 07 September 2009 10:28
To: Darrell Gibson
Cc: email@hidden
Subject: Re: Using an AU directly
Le 7 sept. 2009 à 11:07, Darrell Gibson a écrit :
>
> Hi All,
>
> Following on from a previous post (http://lists.apple.com/archives/Coreaudio-api/2009/Aug/msg00179.html
> ).
>
> I am now trying use an AudioUnits directly on its own, without an
> AUGraph. What I effectively want to do is send audio data into the
> AudioUnit, let the audio unit process the data and then obtain the
> processed data. (I just want the data, I don't actually want an
> audio output.)
>
> In order to do this what I have done is created an instance of the
> AU and then setup an input render callback that supplies the input
> data. The problem I have is without an output device to initiate
> the "pull" my render callback is never called. If I connect an
> output unit it does start to "pull" but I also get an output, which
> I do not want. I want to analyze the output, but not listen to it.
>
> Is there away to start a network of AUs that has does not been
> connected to an output device? By start I mean initiate the "pull".
>
> If not would I have to connect to an output unit, capture the data
> coming in, but not allow the unit to render the data? Could I do
> this by setting up a render callback for the output unit, write the
> input into an AudioBufferList and do not call the AudioUnitRender
> function? Does this sound reasonable?
>
> I assume I can have an AU connected to another AU and still define a
> render callback for the last AU? Will this work?
>
> Thanks for any pointers you can offer.
Just a side note. If you have 10.5, you can have a look at the /
Developer/Examples/CoreAudio/PublicUtility/CAAUProcessor.h class. It's
a class design to do offline rendering (what you're trying to do).
Unfortunately this class is no longer part of the CoreAudio SDK (in
10.6)
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