In this post I want to show how to create an easy sine generator in .NET.

Let’s start with a code listing and then I’ll explain what I’m doing here:

const double frequency	= 1000;
const double amplitude	= 20000;
const long sampleRate	= 44100;
const int durationSec	= 5;

long sampleCount = sampleRate * durationSec;

double timeStep = 1.0 / (double)sampleRate;

double time = 0;
int[] values = new int[sampleCount];
for (long i = 0; i < sampleCount; i++) {
	values[i] = (int)(amplitude * Math.Sin(2 * Math.PI * frequency * time));
	time = time + timeStep;
}

OK, here are some explanations:

• lines 1-4: some constants you can change to e. g. adjust the frequency.
  Note: the frequency cannot be more than half the sampling rate.
• line 6: calculating the number of sampling points.
• line 8: calculating the time between two sampling points.
• lines 10-11: some variable initializations.
• lines 12-15: here finally the value of each sampling point is calculated.

And here is the corresponding code for Visual Basic .NET:

const frequency as double		= 1000
const amplitude as double		= 20000
const sampleRate As Long		= 44100
const durationSec As Integer	= 5

Dim sampleCount As Long
sampleCount = sampleRate * durationSec

Dim timeStep As Double
timeStep = 1.0 / sampleRate

Dim time As Double = 0
Dim values(0 To sampleCount - 1) As Integer
For i As Long = 0 To sampleCount - 1
	values(i) = amplitude * Math.Sin(2 * Math.PI * frequency * time)
	time = time + timeStep
Next i

For sound playback you can now use either an API call like PlaySound (of winmm.dll) or the solution of this great article.

Did you also need to generate a sine in .NET yourself already?

This post is also available in Deutsch.