public void TestReverse()
{
//Arrange
var test = _signal.Copy();
var reversed = _signal.Copy().Samples;
Array.Reverse(reversed);
//Act
test.Reverse();
//Assert
Assert.That(test.Samples, Is.EqualTo(reversed));
}
/// <summary>
/// Decimation preceded by low-pass filtering
/// </summary>
/// <param name="signal"></param>
/// <param name="factor"></param>
/// <param name="filter"></param>
/// <returns></returns>
public DiscreteSignal Decimate(DiscreteSignal signal, int factor, FirFilter filter = null)
{
if (factor == 1)
{
return(signal.Copy());
}
var filterSize = factor > MinResamplingFilterOrder / 2 ?
2 * factor + 1 :
MinResamplingFilterOrder;
var lpFilter = filter;
if (filter == null)
{
lpFilter = DesignFilter.FirLp(filterSize, 0.5f / factor);
signal = lpFilter.ApplyTo(signal);
}
var output = new float[signal.Length / factor];
var pos = 0;
for (var i = 0; i < output.Length; i++)
{
output[i] = signal[pos];
pos += factor;
}
return(new DiscreteSignal(signal.SamplingRate / factor, output));
}
/// <summary>
/// Interpolation followed by low-pass filtering
/// </summary>
/// <param name="signal"></param>
/// <param name="factor"></param>
/// <param name="filter"></param>
/// <returns></returns>
public DiscreteSignal Interpolate(DiscreteSignal signal, int factor, FirFilter filter = null)
{
if (factor == 1)
{
return(signal.Copy());
}
var output = new float[signal.Length * factor];
var pos = 0;
for (var i = 0; i < signal.Length; i++)
{
output[pos] = factor * signal[i];
pos += factor;
}
var lpFilter = filter;
if (filter == null)
{
var filterSize = factor > MinResamplingFilterOrder / 2 ?
2 * factor + 1 :
MinResamplingFilterOrder;
lpFilter = DesignFilter.FirLp(filterSize, 0.5f / factor);
}
return(lpFilter.ApplyTo(new DiscreteSignal(signal.SamplingRate * factor, output)));
}
/// <summary>
/// Time stretching with auto-derived parameters
/// </summary>
/// <param name="signal">Signal</param>
/// <param name="stretch">Stretch factor (ratio)</param>
/// <param name="algorithm">Algorithm for TSM (optional)</param>
/// <returns>Time stretched signal</returns>
public static DiscreteSignal TimeStretch(DiscreteSignal signal,
double stretch,
TsmAlgorithm algorithm = TsmAlgorithm.PhaseVocoderPhaseLocking)
{
if (Math.Abs(stretch - 1.0) < 1e-10)
{
return(signal.Copy());
}
IFilter stretchFilter;
var frameSize = MathUtils.NextPowerOfTwo(1024 * signal.SamplingRate / 16000);
switch (algorithm)
{
case TsmAlgorithm.PhaseVocoder:
stretchFilter = new PhaseVocoder(stretch, frameSize / 10, frameSize);
break;
case TsmAlgorithm.PhaseVocoderPhaseLocking:
stretchFilter = new PhaseLockingVocoder(stretch, frameSize / 8, frameSize);
break;
case TsmAlgorithm.PaulStetch:
stretchFilter = new PaulStretch(stretch, frameSize / 10, frameSize * 4);
break;
default:
stretchFilter = new Wsola(stretch);
break;
}
return(stretchFilter.ApplyTo(signal, FilteringMethod.Auto));
}
/// <summary>
/// Time stretching
/// </summary>
/// <param name="signal">Signal</param>
/// <param name="stretch">Stretch factor (scale)</param>
/// <param name="fftSize">Size of FFT</param>
/// <param name="hopSize">Hop size</param>
/// <param name="algorithm">Algorithm for TSM</param>
/// <returns></returns>
public static DiscreteSignal TimeStretch(DiscreteSignal signal,
double stretch,
int fftSize = 1024,
int hopSize = -1,
TsmAlgorithm algorithm = TsmAlgorithm.Wsola)
{
if (Math.Abs(stretch - 1.0) < 1e-10)
{
return(signal.Copy());
}
var hopAnalysis = hopSize > 0 ? hopSize : fftSize / 4;
IFilter stretchFilter;
switch (algorithm)
{
case TsmAlgorithm.PhaseVocoder:
stretchFilter = new PhaseVocoder(stretch, hopAnalysis, fftSize);
break;
default:
stretchFilter = new Wsola(stretch, fftSize);
break;
}
return(stretchFilter.ApplyTo(signal, FilteringOptions.Auto));
}
/// <summary>
/// Time stretching with parameters set by user
/// </summary>
/// <param name="signal">Signal</param>
/// <param name="stretch">Stretch factor (ratio)</param>
/// <param name="windowSize">Window size (for vocoders - FFT size)</param>
/// <param name="hopSize">Hop size</param>
/// <param name="algorithm">Algorithm for TSM (optional)</param>
/// <returns>Time stretched signal</returns>
public static DiscreteSignal TimeStretch(DiscreteSignal signal,
double stretch,
int windowSize,
int hopSize,
TsmAlgorithm algorithm = TsmAlgorithm.PhaseVocoderPhaseLocking)
{
if (Math.Abs(stretch - 1.0) < 1e-10)
{
return(signal.Copy());
}
IFilter stretchFilter;
switch (algorithm)
{
case TsmAlgorithm.PhaseVocoder:
stretchFilter = new PhaseVocoder(stretch, hopSize, windowSize);
break;
case TsmAlgorithm.PhaseVocoderPhaseLocking:
stretchFilter = new PhaseLockingVocoder(stretch, hopSize, windowSize);
break;
case TsmAlgorithm.PaulStetch:
stretchFilter = new PaulStretch(stretch, hopSize, windowSize);
break;
default:
stretchFilter = new Wsola(stretch, windowSize, hopSize);
break;
}
return(stretchFilter.ApplyTo(signal, FilteringMethod.Auto));
}
/// <summary>
/// Changes RMS relatively to input <paramref name="signal"/>.
/// </summary>
/// <param name="signal">Signal</param>
/// <param name="rmsDb">RMS change in decibels, e.g. -6dB - decrease RMS twice</param>
public static DiscreteSignal ChangeRms(DiscreteSignal signal, double rmsDb)
{
var modified = signal.Copy();
ChangeRms(modified.Samples, rmsDb);
return(modified);
}
/// <summary>
/// Normalizes RMS.
/// </summary>
/// <param name="signal">Signal</param>
/// <param name="rmsDb">RMS in decibels (dBFS), e.g. -6dB, -18dB, -26dB, etc.</param>
public static DiscreteSignal NormalizeRms(DiscreteSignal signal, double rmsDb)
{
var normalized = signal.Copy();
NormalizeRms(normalized.Samples, rmsDb);
return(normalized);
}
/// <summary>
/// Normalizes peak level.
/// </summary>
/// <param name="signal">Signal</param>
/// <param name="peakDb">Peak level in decibels (dBFS), e.g. -1dB, -3dB, etc.</param>
public static DiscreteSignal NormalizePeak(DiscreteSignal signal, double peakDb)
{
var normalized = signal.Copy();
NormalizePeak(normalized.Samples, peakDb);
return(normalized);
}
/// <summary>
/// Time stretching
/// </summary>
/// <param name="signal"></param>
/// <param name="stretch"></param>
/// <param name="fftSize"></param>
/// <param name="hopSize"></param>
/// <returns></returns>
public static DiscreteSignal TimeStretch(DiscreteSignal signal, double stretch, int fftSize = 1024, int hopSize = -1)
{
if (Math.Abs(stretch - 1.0) < 1e-10)
{
return(signal.Copy());
}
var hopAnalysis = hopSize > 0 ? hopSize : fftSize / 4;
var hopSynthesis = (int)(hopAnalysis * stretch);
var vocoder = new PhaseVocoder(hopAnalysis, hopSynthesis, fftSize);
return(vocoder.ApplyTo(signal));
}
/// <summary>
/// Simple resampling as the combination of interpolation and decimation.
/// </summary>
/// <param name="signal"></param>
/// <param name="up"></param>
/// <param name="down"></param>
/// <param name="filter"></param>
/// <returns></returns>
public DiscreteSignal ResampleUpDown(DiscreteSignal signal, int up, int down, FirFilter filter = null)
{
if (up == down)
{
return(signal.Copy());
}
var newSamplingRate = signal.SamplingRate * up / down;
if (up > 20 && down > 20)
{
return(Resample(signal, newSamplingRate, filter));
}
var output = new float[signal.Length * up];
var pos = 0;
for (var i = 0; i < signal.Length; i++)
{
output[pos] = up * signal[i];
pos += up;
}
var lpFilter = filter;
if (filter == null)
{
var factor = Math.Max(up, down);
var filterSize = factor > MinResamplingFilterOrder / 2 ?
8 * factor + 1 :
MinResamplingFilterOrder;
lpFilter = DesignFilter.FirLp(filterSize, 0.5f / factor);
}
var upsampled = lpFilter.ApplyTo(new DiscreteSignal(signal.SamplingRate * up, output));
output = new float[upsampled.Length / down];
pos = 0;
for (var i = 0; i < output.Length; i++)
{
output[i] = upsampled[pos];
pos += down;
}
return(new DiscreteSignal(newSamplingRate, output));
}
/// <summary>
/// Simple resampling (as the combination of interpolation and decimation).
/// </summary>
/// <param name="signal"></param>
/// <param name="newSamplingRate"></param>
/// <returns></returns>
public static DiscreteSignal Resample(DiscreteSignal signal, int newSamplingRate)
{
if (newSamplingRate == signal.SamplingRate)
{
return(signal.Copy());
}
var gcd = MathUtils.Gcd(signal.SamplingRate, newSamplingRate);
var up = newSamplingRate / gcd;
var down = signal.SamplingRate / gcd;
if (up > 20 && down > 20)
{
return(ResampleUpDown(signal, up, down));
}
var output = new float[signal.Length * up];
var pos = 0;
for (var i = 0; i < signal.Length; i++)
{
output[pos] = up * signal[i];
pos += up;
}
var factor = Math.Max(up, down);
var filterSize = factor > MinResamplingFilterOrder / 2 ?
8 * factor + 1 :
MinResamplingFilterOrder;
var lpFilter = DesignFilter.FirLp(filterSize, 0.5f / factor);
var upsampled = lpFilter.ApplyTo(new DiscreteSignal(signal.SamplingRate * up, output));
output = new float[upsampled.Length / down];
pos = 0;
for (var i = 0; i < output.Length; i++)
{
output[i] = upsampled[pos];
pos += down;
}
return(new DiscreteSignal(newSamplingRate, output));
}
/// <summary>
/// Band-limited resampling
/// </summary>
/// <param name="signal"></param>
/// <param name="newSamplingRate"></param>
/// <param name="filter"></param>
/// <param name="order"></param>
/// <returns></returns>
public DiscreteSignal Resample(DiscreteSignal signal,
int newSamplingRate,
FirFilter filter = null,
int order = 15)
{
if (signal.SamplingRate == newSamplingRate)
{
return(signal.Copy());
}
var g = (float)newSamplingRate / signal.SamplingRate;
var input = signal.Samples;
var output = new float[(int)(input.Length * g)];
if (g < 1 && filter == null)
{
filter = new FirFilter(DesignFilter.FirWinLp(MinResamplingFilterOrder, g / 2));
input = filter.ApplyTo(signal).Samples;
}
var step = 1 / g;
for (var n = 0; n < output.Length; n++)
{
var x = n * step;
for (var i = -order; i < order; i++)
{
var j = (int)Math.Floor(x) - i;
if (j < 0 || j >= input.Length)
{
continue;
}
var t = x - j;
float w = (float)(0.5 * (1.0 + Math.Cos(t / order * Math.PI))); // Hann window
float sinc = (float)MathUtils.Sinc(t); // Sinc function
output[n] += w * sinc * input[j];
}
}
return(new DiscreteSignal(newSamplingRate, output));
}
/// <summary>
/// Method implements tube distortion effect
/// </summary>
/// <param name="signal"></param>
/// <param name="filteringOptions"></param>
/// <returns></returns>
public DiscreteSignal ApplyTo(DiscreteSignal signal,
FilteringOptions filteringOptions = FilteringOptions.Auto)
{
var maxAmp = signal.Samples.Max(s => Math.Abs(s));
if (Math.Abs(maxAmp) < 1e-10)
{
return(signal.Copy());
}
IEnumerable <float> tempZ;
if (Math.Abs(Q) < 1e-10)
{
tempZ = signal.Samples.Select(s =>
{
var q = Gain * s / maxAmp;
return(Math.Abs(q - Q) < 1e-10 ?
1.0f / Dist :
(float)(q / (1 - Math.Exp(-Dist * q))));
});
}
else
{
tempZ = signal.Samples.Select(s =>
{
var q = Gain * s / maxAmp;
return(Math.Abs(q - Q) < 1e-10 ?
(float)(1.0 / Dist + Q / (1 - Math.Exp(Dist * Q))) :
(float)((q - Q) / (1 - Math.Exp(-Dist * (q - Q))) + Q / (1 - Math.Exp(Dist * Q))));
});
}
var maxZ = tempZ.Max(z => Math.Abs(z));
var tempY = tempZ.Zip(signal.Samples, (z, x) => Mix * z * maxAmp / maxZ + (1 - Mix) * x);
var maxY = tempY.Max(y => Math.Abs(y));
var output = tempY.Select(y => y * maxAmp / maxY);
return(_outputFilter.ApplyTo(new DiscreteSignal(signal.SamplingRate, output)));
}
/// <summary>
/// Method implements simple distortion effect
/// </summary>
/// <param name="signal"></param>
/// <param name="filteringOptions"></param>
/// <returns></returns>
public DiscreteSignal ApplyTo(DiscreteSignal signal,
FilteringOptions filteringOptions = FilteringOptions.Auto)
{
var maxAmp = signal.Samples.Max(s => Math.Abs(s));
if (Math.Abs(maxAmp) < 1e-8)
{
return(signal.Copy());
}
var tempZ = signal.Samples.Select(s =>
{
var q = Gain * s / maxAmp;
return(Math.Sign(q) * (1 - Math.Exp(-Math.Abs(q))));
});
var maxZ = tempZ.Max(z => Math.Abs(z));
var tempY = tempZ.Zip(signal.Samples, (z, x) => Mix * z * maxAmp / maxZ + (1 - Mix) * x);
var maxY = tempY.Max(y => Math.Abs(y));
var output = tempY.Select(y => (float)(y * maxAmp / maxY));
return(new DiscreteSignal(signal.SamplingRate, output));
}
