How can you add a fixed gain to an AudioGraph?

Is there an AudioUnit that can apply a fixed gain within an AudioGraph? Are there other alternative me开发者_如何学编程thods?

Unfortunately iOS only ships with 3 built-in AudioUnits that you can use, though it is possible to process raw sample data on the fly by setting up an AudioUnitRenderer. However, guessing from the name, you probably want to use the AU3DEmbeddedMixer AudioUnit if you are only interested in applying a quick gain reduction.

I'm not sure of the exact parameters required by this AU, but it shouldn't be too hard to figure out the header files.