I need help programming a Audio Unit that wraps a 3rd party audio unit.

I am trying to develop an Audio Unit instrument using Xcode. I want my AU to load an instance of a 3rd party Audio Unit called Massive by Native Instruments. I want all MIDI notes passed to my AU to go into the Massive AU and the output of that is the output of my AU.

I just want my AU to programmatically control some variables of the 3rd party one and pass through all sound/MIDI to it too.

I can't seem to find any examples of how to do this. Also, I am a newbie with Core Audio and the documentation is very hard to understand. I don't really know what I'm doing with Core Audio...

Can someone please tell me how to do this?


3 Answers 3


Spend some more time reading the documentation. Discuss in the Apple Developer forums.

Forget your project and use something that's already been made: http://www.plogue.com/products/bidule/

  • Bidule currently does not offer a free trial link. And I don't have a Mac Developer Program subscription. I really want to control a 3rd party AU with code (C++) and pass all input/output to and from it. How would I do this? I have all the core audio guides... but I am just begining to understand... Am I supposed to make some kind of connection in my AU constructor class? Connect its input to the 3rd party AU input and same with outputs or what?
    – Andrei
    Aug 8, 2012 at 2:32
  • I don't know, I don't develop AUs. But you should be able to figure it out with the API documentation, taken that you've got reasonable experience in coding and have dabbled with the Apple APIs and dev tools a bit. Aug 8, 2012 at 4:03

I did this a couple of years ago and published the results at last years International Computer Music Conference (http://eprints.bournemouth.ac.uk/18249/1/ICMC2011%2DPaper_Final_Camera_Ready_ver2.pdf). It is fairly tricky to do and I could not find any example code. I found the hardest aspect was managing the UI.

  • If you could email ([email protected]) me your source code I would appreciate it.
    – Andrei
    Aug 8, 2012 at 13:32
  • As far as I can see, I must create a local AU Host (AUGraph) within my AU.
    – Andrei
    Aug 8, 2012 at 13:34
  • Not unless you are paying? Yes that is about it.
    – Bit Depth
    Aug 8, 2012 at 21:52

Besides AU, there's a plugin named Patcher of FL Studio for doing this to VST's.

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