IOS apply effects all over my audio engine sound result

Question

is there a way in ios to put over my audio engine a kind of layer to apply DSP on all of my stuff?

In fact I want to reproduce something like add a dsp hardware between a mixer and my speaker to apply an echo for example to the sound result without dealing with the stream.

Just say for example get the global sound and apply an EQ High pass on it, that's it.

Thanks for your help

Answer 1

If you're using AVAudioPlayer you can use MTAudioProcessingTap to do this. It isn't the simplest task but here are some resources that should help:

MTAudioProcessingTap Audio Processor shows how to apply a bandpass filter to the audio data: https://developer.apple.com/library/ios/samplecode/AudioTapProcessor/Introduction/Intro.html

Processing AVPlayer’s audio with MTAudioProcessingTap is a fairly complete example showing how to create a tap: http://chritto.wordpress.com/2013/01/07/processing-avplayers-audio-with-mtaudioprocessingtap/