/// <summary>
/// Creates the sound wave of one beat with specified bpm
/// </summary>
/// <param name="bpm">Beats per minute</param>
/// <returns></returns>
public static short[] GenerateBeatWave(int bpm)
{
// 60 / bpm gives us the period of beat envelope
// data loss from casting to int will be negligible
int length = (int)(60f / bpm * Config.SAMPLE_RATE);
// the beat is generated by mixing a sawtooth and a square wave
short[] sawtooth = SampleWaveForm(Pitch.A3, length, x => x / 5, WaveForms.SawtoothWave, Config.SAMPLE_RATE);
short[] square = SampleWaveForm(Pitch.A3, length, x => x / 7, WaveForms.SquareWave, Config.SAMPLE_RATE);
short[] toneWave = Mixing.MixListOfWaves(new List <short[]> {
sawtooth, square
});
// to get the right loudness progression, we multiply the tone wave by an exponential function
short[] wave = new short[length];
float frequency = 50; // determined by trial and error
for (int i = 0; i < length; ++i)
{
double expValue = i < length?Math.Pow(0.0001, (double)i / length) : 0;
wave[i] = Convert.ToInt16(expValue * toneWave[i]);
}
return(wave);
}
/// <summary>
/// Converts to a corresponding sound wave
/// </summary>
/// <param name="sampleRate">Sample rate</param>
/// <param name="shift">Pitch shift, if any</param>
/// <param name="waveForm">Wave form</param>
/// <returns></returns>
public short[] ConvertToWave(int sampleRate, Shift shift, WaveFormEquation waveForm)
{
int length = ConvertDurationToLength(sampleRate);
List <short[]> waves = new List <short[]> {
};
foreach (Pitch frequency in Frequencies)
{
waves.Add(Wave.SampleWaveForm(frequency, length, shift, waveForm, sampleRate));
}
short[] mixed = Mixing.MixListOfWaves(waves);
return(mixed);
}
/// <summary>
/// Generates a new recording from all the changes that have been made
/// (e.g. added harmony, shifted scale).
/// </summary>
public void RegenerateRecording()
{
// dispose recording channel and recording output if they exist
if (recordingOutput != null)
{
recordingOutput.Dispose();
}
if (recordingChannel != null)
{
recordingChannel.Dispose();
}
// generate waves from epochs
short[] melody = ConcatWaves(melodyEpochs);
short[] harmony = ConcatWaves(harmonyEpochs);
harmony = harmony.MultiplyToLength(melody.Length);
if (beatWave == null)
{
beatWave = GenerateBeat(bpm, melody.Length);
}
// mix melody, harmony and beat
short[] combinedWave = Mixing.MixListOfWaves(new List <short[]> {
melody, harmony, beatWave
});
byte[] binaryWave = Wave.ConvertShortWaveToBytes(combinedWave);
// write the result into a file
using (FileStream fs = File.Create(Filename))
{
Wave.WriteToStream(fs, binaryWave, melody.Length,
Config.SAMPLE_RATE, Config.BITS_PER_SAMPLE, Config.CHANNELS);
}
// create new channel and output for playing the recording
recordingChannel = new WaveChannel32(new WaveFileReader(Filename));
recordingChannel.Volume = 1.0f;
recordingOutput = new DirectSoundOut();
recordingOutput.Init(recordingChannel);
}
