iphone - What's the difference between the Apple audio frameworks?

Question

In the documentation I see several Apple frameworks for audio. All of them seem to be targeted at playing and recording audio. So I wonder what the big differences are between these?

• Audio Toolbox
• Audio Unit
• AV Foundation
• Core Audio

Did I miss a guide that gives a good overview of all these?

Answer 1

I made a brief graphical overview of Core Audio and the its (containing) frameworks:

The framework closest to the hardware is Audio Unit. Based on that there is OpenAL and AudioToolbox with AudioQueue. On top you can find the Media Player and AVFoundation (Audio & Video) frameworks.

Now it depends on what you want to do: just a small recording, use AVFoundation, which is the most easiest one to use. (Media Player has no options for recording, it is - as the name says - just a media player.)

Do you want to do serious real time signal processing? Use Audio Unit. But believe me, this is hardest way. :-)

With iOS 8.0 Apple introduced AVAudioEngine, an Objective-C/Swift based audio graph system in AV Foundation. This encapsulate some dirty C-stuff from Audio Units. Due to the complexity of Audio Unit it is maybe worth a look.

Further readings in the Apple Documentation:

• Core Audio Overview: Introduction
• Multimedia Programming Guide
• Audio & Video Starting Point