AVAudioEngine & AVAudioPlayer. setVoiceProcessingEnabled low volume output

Question

As the title suggests I am using AVAudioEngine for SFSpeechRecognition input & AVAudioPlayer for sound output.

Apple says in this talk that the setVoiceProcessingEnabled function very usefully cancels the output from speaker to the mic. I set voiceProcessing on the AVAudioInputNode and AVAudioOutputNode.

When running xcode when speechRecognitionEnabled:YES throws the following error:

throwing 18,446,744,073,709,551,615
  from AU (0x13bf98dd0): auou/vpio/appl, render err: 18,446,744,073,709,551,615

There is no error thrown when setting up the nodes and it seems to work however the volume is low, even when the system volume is turned up. Any solution to this would be much appreciated.

I tried various AVAudioEngine node setups. One setup with a mixer node and one without. I am expecting the audio levels to be loud, in conjunction with the system volume.

Answer 1

Did you enable voice processing on both the input and output nodes?

Here is what I tried and it worked (somewhat):

audioInputNode=engine.inputNode 
    audioInputNode.volume=0
    do{
        try audioInputNode.setVoiceProcessingEnabled(true)
    }
    catch{
        print("Could not enable voice processing in audioinputnode")
    }
    let outputNode = engine.outputNode
    do{
        try outputNode.setVoiceProcessingEnabled(true)
    }
    catch{
        print("Could not enable voice processing in output")
    }

I say worked "somewhat" because when I record the mic input, the sound from the speaker is definitely cancelled out, but the mic audio recorded to a file is a little choppy