18-01-09_microphone_level_meter

Audio Level Monitor

This is a sample project I made to help myself remember how to easily provide highspeed access to the microphone device.

Key Code

Import NAudio:

using NAudio.Wave; // installed with nuget

Continuously listen to the microphone:

int RATE=44100; // sample rate of the microphone
int BUFFER_SAMPLES=1024; // powers of two help for FFT

var waveIn = new WaveInEvent();
waveIn.DeviceNumber = 0; // change this to select different sound inputs
waveIn.WaveFormat = new NAudio.Wave.WaveFormat(RATE, 1); // 1 for mono
waveIn.DataAvailable += OnDataAvailable; // this function must exist
waveIn.BufferMilliseconds = (int)((double)BUFFER_SAMPLES / (double)RATE * 1000.0);
waveIn.StartRecording();

Do this when a new buffer gets filled:

private void OnDataAvailable(object sender, WaveInEventArgs args)
{
	// this example will display the peak audio value of the buffer
    float max = 0;

    // interpret as 16 bit audio
    for (int index = 0; index < args.BytesRecorded; index += 2)
    {
        short sample = (short)((args.Buffer[index + 1] << 8) |
                                args.Buffer[index + 0]);
        var sample32 = sample / 32768f; // to floating point
        if (sample32 < 0) sample32 = -sample32; // absolute value 
        if (sample32 > max) max = sample32; // is this the max value?
    }
	System.Console.WriteLine(max+"\n"); // display the peak audio value
}

Useful Links

• naudio GitHub page
• naudio Recording Level Meter (docs)
• naudio Recording a WAV (docs)