AudioKit - How to get Real Time floatChannelData from Microphone?

Question

I'm new to Audiokit and I'm trying to do some real-time digital signal processing on input audio from the microphone.

I know the data I want is in AKAudioFile's FloatChannelData, but what if I want to obtain this in real-time? I'm currently using AKMicrophone, AKFrequencyTracker, AKNodeOutputPlot, AKBooster and I'm plotting the tracker's amplitude data. However, that data is not the same as the audio signal (as you know, it's the RMS). Is there any way I can obtain the signal's Float data from the mic? Or even from the AKNodeOutputPlot? I just need read-access.

AKSettings.audioInputEnabled = true
mic = AKMicrophone()
plot = AKNodeOutputPlot(mic, frame: audioInputPlot.bounds)
tracker = AKFrequencyTracker.init(mic)
silence = AKBooster(tracker,gain:0)
AudioKit.output = silence
AudioKit.start()

The creator of recommends here:

AKNodeOutputPlot works, its one short file. You're basically just tapping the node and grabbing the data.

How would this work in my viewController if if have an instance of plot (AKNodeOutputPlot), mic(AKMicrophone) and want to output those values to a label?

Answer 1

Use a tap on which ever node you want to get the data out from. I used AKNodeOutputPlot in my quote above because its is fairly straightforward, just using that data as input for a plot, but you could take the data and do whatever with it. In this code (from AKNodeOutputPlot):

internal func setupNode(_ input: AKNode?) {
    if !isConnected {
        input?.avAudioNode.installTap(
            onBus: 0,
            bufferSize: bufferSize,
            format: nil) { [weak self] (buffer, _) in

                guard let strongSelf = self else {
                    AKLog("Unable to create strong reference to self")
                    return
                }
                buffer.frameLength = strongSelf.bufferSize
                let offset = Int(buffer.frameCapacity - buffer.frameLength)
                if let tail = buffer.floatChannelData?[0] {
                    strongSelf.updateBuffer(&tail[offset], withBufferSize: strongSelf.bufferSize)
                }
        }
    }
    isConnected = true
}

You get the buffer data in real time. Here we just send it to "updateBuffer" where it gets plotted, but instead of plotting you'd do something else.