Capture audio from Microphone

crigint

Hi all,
in my Xamarin.Mac app I would like to capture audio from built-in microphone.

I can't convert the sample buffer into an audio file to play when the capture is end.

I start recording successfully in this method:

`
private bool _SetupMic()
{
// configure the capture session for low resolution, change this if your code
// can cope with more data or volume
captureSession = new AVCaptureSession()
{
SessionPreset = AVCaptureSession.PresetPhoto //AVCaptureSession.PresetiFrame1280x720
};

        // create a device input and attach it to the session
        var captureDevice = AVCaptureDevice.GetDefaultDevice(AVMediaTypes.Audio);
        captureDeviceInput = AVCaptureDeviceInput.FromDevice(captureDevice);
        if (captureDeviceInput == null)
        {

            return false;
        }

        if (captureSession.CanAddInput(captureDeviceInput))
            captureSession.AddInput(captureDeviceInput);
        else
        {

            return false;
        }


        AVCaptureAudioDataOutput output = new AVCaptureAudioDataOutput
        {

        };
        output.AudioSettings = new AudioSettings();


        CoreFoundation.DispatchQueue audioCaptureQueue = new CoreFoundation.DispatchQueue("Audio Capture Queue");
        output.SetSampleBufferDelegateQueue(this, audioCaptureQueue);

        if (captureSession.CanAddOutput(output))
            captureSession.AddOutput(output);
        else
        {

            return false;
        }

        captureSession.StartRunning();
        return true;
    }`

Then I get each sample buffer and save it in a file:

`
[Export("captureOutput:didOutputSampleBuffer:fromConnection:")]
public virtual void DidOutputSampleBuffer(AVCaptureOutput captureOutput, CMSampleBuffer sampleBuffer, AVCaptureConnection connection)
{
// process samples (video frames) here
_SampleBuffer = sampleBuffer;
var blockBuffer = _SampleBuffer.GetDataBuffer();
var blockBufferDataLength = blockBuffer.DataLength;
var blockBufferData = new byte[blockBufferDataLength];

        var status = blockBuffer.CopyDataBytes(0, blockBufferDataLength, out var destination);

        var path = System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory.Replace("MonoBundle", "Resources"), "mic.mp3");
        using (var stream = new FileStream(path, FileMode.Append))
        {
            stream.Write(destination, 0, destination.Length);
        }
        sampleBuffer.Dispose();
    }`

The file is successfully created but if I try to play it in a player, it has 0 seconds length.

How can I save all sample buffer into one correct file audio that I can play in a second time?

Thanks in advance.

crigint

Nobody can help me?