/// <summary>
/// Method for computing direct STFT of a signal block.
/// STFT (spectrogram) is essentially the list of spectra in time.
/// </summary>
/// <param name="samples">The samples of signal</param>
/// <returns>STFT of the signal</returns>
public List <Tuple <float[], float[]> > Direct(float[] samples)
{
// pre-allocate memory:
var len = (samples.Length - _windowSize) / _hopSize;
var stft = new List <Tuple <float[], float[]> >();
for (var i = 0; i <= len; i++)
{
stft.Add(new Tuple <float[], float[]>(new float[_fftSize], new float[_fftSize]));
}
// stft:
var windowedBuffer = new float[_windowSize];
for (int pos = 0, i = 0; pos + _windowSize < samples.Length; pos += _hopSize, i++)
{
samples.FastCopyTo(windowedBuffer, _windowSize, pos);
if (_window != WindowTypes.Rectangular)
{
windowedBuffer.ApplyWindow(_windowSamples);
}
_fft.Direct(windowedBuffer, stft[i].Item1, stft[i].Item2);
}
return(stft);
}
/// <summary>
/// Method for computing direct STFT of a signal block.
/// STFT (spectrogram) is essentially the list of spectra in time.
/// </summary>
/// <param name="samples">The samples of signal</param>
/// <returns>STFT of the signal</returns>
public List <(float[], float[])> Direct(float[] samples)
{
// pre-allocate memory:
var len = (samples.Length - _windowSize) / _hopSize;
var stft = new List <(float[], float[])>(len + 1);
for (var i = 0; i <= len; i++)
{
stft.Add((new float[_fftSize], new float[_fftSize]));
}
// stft:
var windowedBuffer = new float[_fftSize];
for (int pos = 0, i = 0; pos + _windowSize < samples.Length; pos += _hopSize, i++)
{
samples.FastCopyTo(windowedBuffer, _windowSize, pos);
windowedBuffer.ApplyWindow(_windowSamples);
var(re, im) = stft[i];
_fft.Direct(windowedBuffer, re, im);
}
return(stft);
}
/// <summary>
/// Method for computing direct STFT of a signal block.
/// STFT (spectrogram) is essentially the list of spectra in time.
/// </summary>
/// <param name="input">Samples of input signal</param>
/// <returns>STFT of the signal</returns>
public List <(float[], float[])> Direct(float[] input)
{
// pre-allocate memory:
var len = (input.Length - _windowSize) / _hopSize + 1;
var stft = new List <(float[], float[])>(len);
for (var i = 0; i < len; i++)
{
stft.Add((new float[_fftSize], new float[_fftSize]));
}
// stft:
var windowedBuffer = new float[_fftSize];
var pos = 0;
for (var i = 0; i < len; pos += _hopSize, i++)
{
input.FastCopyTo(windowedBuffer, _windowSize, pos);
windowedBuffer.ApplyWindow(_windowSamples);
var(re, im) = stft[i];
_fft.Direct(windowedBuffer, re, im);
}
// last (incomplete) frame:
stft.Add((new float[_fftSize], new float[_fftSize]));
Array.Clear(windowedBuffer, 0, _fftSize);
input.FastCopyTo(windowedBuffer, input.Length - pos, pos);
windowedBuffer.ApplyWindow(_windowSamples);
var(lre, lim) = stft.Last();
_fft.Direct(windowedBuffer, lre, lim);
return(stft);
}
/// <summary>
/// Does Fast Mellin Transform.
/// </summary>
/// <param name="input">Input array of samples</param>
/// <param name="outRe">Output array of real parts</param>
/// <param name="outIm">Output array of imaginary parts</param>
public void Direct(float[] input, float[] outRe, float[] outIm)
{
MathUtils.InterpolateLinear(_linScale, input, _expScale, outRe);
for (var i = 0; i < outRe.Length; i++)
{
outRe[i] *= (float)Math.Pow(_expScale[i], _beta);
outIm[i] = 0;
}
_fft.Direct(outRe, outRe, outIm);
}
