/// <summary>
/// Generate a wav loop stream containing a 440Hz sine wave.
/// </summary>
/// <param name="nrSeconds">the length of the wav stream in seconds</param>
/// <returns>a loop stream containing 'nrSeconds' of wav sine wave</returns>
private LoopStream GenerateSineWave(uint nrSeconds)
{
// Fill the data array with sample data
var data = new WaveDataChunk();
var numSamples = waveFormat.SampleRate * waveFormat.Channels * nrSeconds;
data.AudioSamples = new short[numSamples];
var amplitude = 32760; // Max amplitude for 16-bit audio
var freq = 440.0f; // Concert A: 440Hz
// The "angle" used in the function, adjusted for the number of channels and sample rate.
// This value is like the period of the wave.
double t = (Math.PI * 2 * freq) / (waveFormat.SampleRate * waveFormat.Channels);
for (uint i = 0; i < numSamples - waveFormat.Channels; i++)
{
// Fill with a simple sine wave at max amplitude
for (int channel = 0; channel < waveFormat.Channels; channel++)
{
data.AudioSamples[i + channel] = Convert.ToInt16(amplitude * Math.Sin(t * i));
}
}
data.Length = (uint)(data.AudioSamples.Length * (waveFormat.BitsPerSample / 8));
return(CreateStream(data));
}
/// <summary>
/// Create a loop stream of the wav data.
/// </summary>
/// <param name="data">wav data</param>
/// <returns>a loop stream containing the wav data</returns>
private LoopStream CreateStream(WaveDataChunk data)
{
if (data == null)
{
return(null);
}
var stream = new MemoryStream();
var writer = new BinaryWriter(stream);
// Write the wav header
var header = new AudioHeader();
writer.Write(header.GetRiffHeader(waveFormat, data.Length));
// Write the data chunk
foreach (short dataPoint in data.AudioSamples)
{
writer.Write(dataPoint);
}
writer.Seek(4, SeekOrigin.Begin);
var streamsize = (uint)writer.BaseStream.Length;
writer.Write(streamsize - 8);
writer.Flush();
stream.Position = 0;
return(new LoopStream(stream, waveFormat));
}
/// <summary>
/// Get silence data.
/// </summary>
private WaveDataChunk GetSilence(uint nrSeconds)
{
// Fill the data array with silence samples.
var data = new WaveDataChunk();
var numSamples = waveFormat.SampleRate * waveFormat.Channels * nrSeconds;
data.AudioSamples = new short[numSamples];
data.Length = (uint)(data.AudioSamples.Length * (waveFormat.BitsPerSample / 8));
return(data);
}
/// <summary>
/// Get silence data.
/// </summary>
public WaveDataChunk GetSilence(uint nrSeconds)
{
// Fill the data array with silence samples.
var data = new WaveDataChunk();
var numSamples = waveFormat.SampleRate * waveFormat.Channels * nrSeconds;
data.AudioSamples = new short[numSamples];
for (uint i = 0; i < numSamples - 1; i++)
{
for (int channel = 0; channel < waveFormat.Channels; channel++)
{
data.AudioSamples[i + channel] = 0;
}
}
data.Length = (uint)(data.AudioSamples.Length * (waveFormat.BitsPerSample / 8));
return(data);
}
