How can I save the raw data captured (the buffer) by the microphone?

[Denis Candido]

Hello,

My plan is to do some raw data processment after capturing it, saving in a .raw data or kind of. Can I do it with current AudioKit support?

If possible, I need to send this raw data via JSON to my Python server. Some way to convert the buffer to literally binary data, so I can send using REST.

Is this possible with AudioKit or I will have to go to the deep and dark world of the Apple's documentation?

//Denis

[Aurelius Prochazka Ph.D.]

Take a look at how we tap the data off of nodes to create the plots.  You can probably post the data to your server instead of plotting it.  Or at least save it for sending on a separate thread.

Aure

[Denis Candido]

Hello Aure,

I tried something like this:

override func viewWillAppear(_ animated: Bool) {

        

        mic = AKMicrophone()

        

        installTap(mic!)

    }

    

    

    override func viewWillDisappear(_ animated: Bool) {

        mic?.avAudioNode.removeTap(onBus: 0)

    }

    

    func installTap(_ input:AKNode) {

        

        input.avAudioNode.installTap(onBus: 0, bufferSize: 1024, format: AudioKit.format) { [weak self] (buffer, time) -> Void in

            self?.signalTracker(didReceivedBuffer: buffer, atTime: time)

        }

    }

    

    

    

    func signalTracker(didReceivedBuffer buffer: AVAudioPCMBuffer, atTime time: AVAudioTime){

        

        let elements = UnsafeBufferPointer(start: buffer.floatChannelData?[0], count:1024)

        print (elements)

        print(elements.count)

        

    }

But doesn't print what I expected... I expected an Array of Float but what I have is this:

UnsafeBufferPointer(start: 0x00007fbf1f80bc00, count: 1024)

1024

Can you please help me with this?

[Denis Candido]

Hello Aure,

Problem solved with:

func signalTracker(didReceivedBuffer buffer: AVAudioPCMBuffer, atTime time: AVAudioTime){

        

        let elements = UnsafeBufferPointer(start: buffer.floatChannelData?[0], count:8192)

        

        var sample = [Float]()

        

        for i in 0..<8192 {

            sample.append(elements[i])

        }

        print (sample)

        print(sample.count)

        

        

        

    }

I saw it at the AKFFTTap. Thanks.

Em segunda-feira, 29 de maio de 2017 21:09:46 UTC-3, Aurelius Prochazka Ph.D. escreveu:

[Denis Candido]

Hello Aure,

Can you tell me what's the difference between these codes:

Way used at AKFFTTap.swift to read buffer samples:

let elements = UnsafeBufferPointer(start: buffer.floatChannelData?[0], count:self.bufferSize)

        

for i in 0..<self.bufferSize {

     self.sample.append(elements[i])

}

Similar way used at AKAmplitudeTap.swift (similar because there calculates the RMS...):

for i in 0 ..< Int(self.bufferSize) {

    self.sample.append(Float((buffer.floatChannelData?.pointee[i]) ?? 0.0))

}

There's any difference between them?

Thanks,

Denis. 

[Aurelius Prochazka Ph.D.]

The AKFFTTap.swift on AudioKit 3.7 doesn't have that code. What version are you looking at?  In any event, there might not have been any reason one way was chosen or the other, could just be when it was introduced. 

Aure