/// <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 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));
}
