public static List <Complex[]> STFT(double[] audio, int hopSize, double[] window)
{
/**
* Short Time Fourier Transform
*/
int num_blocks = (audio.Length - window.Length) / hopSize;
//window too large or stepSize too large to get a single windowed block out of it
if (num_blocks < 1)
{
return(null);
}
List <Complex[]> ffts = new List <Complex[]>();
Parallel.For(0, num_blocks, windowed_block =>
{
FftSharp.Complex[] buffer = new FftSharp.Complex[window.Length];
int sourceIndex = windowed_block * hopSize;
for (int i = 0; i < window.Length; i++)
{
buffer[i].Real = audio[sourceIndex + i] * window[i] / window.Length;
}
FftSharp.Transform.FFT(buffer);
ffts.Add(buffer);
});
return(ffts);
}
//Modified to be equivalent to Fourier.STFT code.
public Complex[][] Process(double whiteNoiseThreshold = 0)
{
if (FftsToProcess < 1)
{
return(null);
}
int newFftCount = FftsToProcess;
Complex[][] newFfts = new Complex[newFftCount][];
Parallel.For(0, newFftCount, newFftIndex =>
{
FftSharp.Complex[] buffer = new FftSharp.Complex[settings.FftSize];
int sourceIndex = newFftIndex * settings.StepSize;
for (int i = 0; i < settings.FftSize; i++)
{
buffer[i].Real = newAudio[sourceIndex + i] * settings.Window[i] / settings.FftSize;
}
FftSharp.Transform.FFT(buffer);
AudioAnalysis.Filters.WhiteNoiseFilter(buffer, whiteNoiseThreshold);
newFfts[newFftIndex] = new Complex[settings.FftSize];
for (int i = 0; i < settings.FftSize; i++)
{
newFfts[newFftIndex][i] = buffer[i];
}
});
for (int i = 0; i < newFftCount; i++)
{
ffts.Add(newFfts[i]);
ffts_complex.Add(newFfts[i]);
}
FftsProcessed += newFfts.Length;
newAudio.RemoveRange(0, newFftCount * settings.StepSize);
PadOrTrimForFixedWidth();
return(newFfts);
}
