Generation of mono frequency audio file/signal.

AudioGenerate.cs

using System;
using NAudio.Wave;

namespace GM.SP.Audio
{
	public static class AudioGenerate
	{
		/// <summary>
		/// Generates a mono frequency audio file.
		/// </summary>
		public static void GenerateAudioFile(string fileName,TimeSpan length,int sampleRate,int frequency)
		{
			float[] samples = Generate(length, sampleRate, frequency);

			WaveFormat format = new WaveFormat(sampleRate, 2);
			samples = AudioUtility.Zip(samples, samples);

			// convert from samples to bytes
			byte[] bytes = new byte[samples.Length * 2];
			for(int i = 0, j = 0; i < samples.Length; ++i) {
				float sample = samples[i];
				short valueShort = (short)(0.5 + sample * ((sample > 0) ? short.MaxValue : 32768));
				ushort valueUShort = (ushort)(valueShort + 65536);
				bytes[j++] = (byte)valueUShort;
				bytes[j++] = (byte)(valueUShort >> 8);
			}

			// write to file
			WaveFileWriter writer = null;
			try {
				writer = new WaveFileWriter(fileName, format);
				writer.Write(bytes, 0, bytes.Length);
				writer.Flush();
			} finally {
				writer?.Dispose();
			}
		}

		/// <summary>
		/// Generates a mono frequency signal.
		/// </summary>
		public static float[] Generate(TimeSpan length, int sampleRate, int frequency)
		{
			float[] samples = new float[(int)(length.TotalSeconds * sampleRate)];

			double step = (2 * Math.PI * frequency) / sampleRate;

			double current = 0;

			for(int i = 0; i < samples.Length; ++i) {
				current += step;
				samples[i] = (float)Math.Sin(current);
			}

			return samples;
		}
	}
}