public Bitmap ToImage(ref double[] signal, int samplerate)
{
using (new DebugTimer("Spectrogram: ToImage()"))
{
Console.Out.WriteLine("Spectrogram: Transform Sound to Image");
Complex[] spectrum = SpectrogramUtils.padded_FFT(ref signal);
//const size_t width = (spectrum.size()-1)*2*pixpersec/samplerate;
double lastSpectrumIndex = spectrum.Length - 1; // last spectrum index
double pixelsPerSample = (double)pixpersec / (double)samplerate;
double widthDouble = lastSpectrumIndex * 2 * pixelsPerSample;
int width = MathUtils.RoundAwayFromZero(widthDouble);
Console.Out.WriteLine("Width: {0}", width);
//int testWidt = (int) (signal.Length * pixpersec);
// transformation of frequency in hz to index in spectrum
double filterscale = ((double)spectrum.Length * 2) / samplerate;
Console.Out.WriteLine("Filterscale: {0}", filterscale);
Filterbank filterbank = Filterbank.GetFilterbank(frequency_axis, filterscale, basefreq, bandwidth, overlap);
int bands = (int)filterbank.NumBandsEst(maxfreq);
int top_index = (int)((double)maxfreq * filterscale);
// maxfreq has to be at most nyquist
Debug.Assert(top_index <= spectrum.Length);
//std::vector<real_vec> image_data;
var image_data = new List <double[]>();
for (int bandidx = 0;; ++bandidx)
{
// TODO: support cancelling this process
// filtering
Pair <int, int> range = filterbank.GetBand(bandidx);
// Output progress
Console.Write("Processing band {0} of {1} ({2:0.00} Hz - {3:0.00} Hz = {4:0.00} Hz)\r", bandidx, bands, range.First / filterscale, range.Second / filterscale, (range.Second - range.First) / filterscale);
/*
* Console.Out.WriteLine("-----");
* Console.Out.WriteLine("spectrum size: {0}", spectrum.Length);
* Console.Out.WriteLine("lowidx: {0:0.00} highidx: {1:0.00}", range.First, range.Second);
* Console.Out.WriteLine("(real)lowfreq: {0:0.00} (real)highfreq: {1:0.00}", range.First / filterscale, range.Second/filterscale);
* Console.Out.WriteLine("actual width: {0:0.00} hz", (range.Second-range.First)/filterscale);
* Console.Out.WriteLine("vertical values: {0:0.00}", (range.Second-range.First));
* Console.Out.WriteLine("crowd sample: {0:0.00}", (range.Second-range.First-1)*2);
* Console.Out.WriteLine("theoretically staci: {0:0.00} hz samplerate", 2*(range.Second-range.First)/filterscale);
* Console.Out.WriteLine("width: {0}", width);
*/
// take the complex samples specified by the range and copy into filterband
int filterbandLength = range.Second - range.First;
var filterband = new Complex[filterbandLength];
//std::copy(spectrum.begin()+range.first,
// spectrum.begin()+std::min(range.second, top_index),
// filterband.begin());
int sourceIndexStart = range.First;
int sourceIndexEnd = Math.Min(range.Second, top_index);
int length = sourceIndexEnd - sourceIndexStart;
if (sourceIndexStart < sourceIndexEnd)
{
Array.Copy(spectrum, sourceIndexStart, filterband, 0, length);
}
// if the first range index is higher than the maximum index, we have reached the end
if (range.First > top_index)
{
break;
}
// if the second range index is higher than the maximum index, we are at the last band
if (range.Second > top_index)
{
//std::fill(filterband.begin()+top_index-range.first,
// filterband.end(), Complex(0,0));
// not neccesary as c# already defaults the rest of the array to a Complex(0,0)
}
// windowing
ApplyWindow(ref filterband, range.First, filterscale);
// envelope detection
double[] envelope = SpectrogramUtils.GetEnvelope(ref filterband);
// resampling
envelope = SpectrogramUtils.Resample(envelope, width);
image_data.Add(envelope);
}
SpectrogramUtils.NormalizeImageCutoffNegative(ref image_data);
return(MakeImage(image_data));
}
}
public double[] SynthetizeSine(Bitmap image, int samplerate)
{
using (new DebugTimer("Spectrogram: SynthetizeSine(Bitmap)"))
{
int samples = image.Width * samplerate / pixpersec;
var spectrum = new Complex[samples / 2 + 1];
double filterscale = ((double)spectrum.Length * 2) / samplerate;
Filterbank filterbank = Filterbank.GetFilterbank(frequency_axis, filterscale, basefreq, bandwidth, overlap);
for (int bandidx = 0; bandidx < image.Height; ++bandidx)
{
// TODO: support cancelling this process
OutputBandProgress(bandidx, image.Height);
double[] envelope = EnvelopeFromSpectrogram(image, bandidx);
// Find maximum number when all numbers are made positive.
//double max = envelope.Max((b) => Math.Abs(b));
//Console.WriteLine(max);
// random phase between +-pi
double phase = SpectrogramUtils.RandomDoubleMinus1ToPlus1() * Math.PI;
var bandsignal = new double[envelope.Length * 2];
for (int j = 0; j < 4; ++j)
{
double sine = Math.Cos(j * Math.PI / 2 + phase);
for (int i = j; i < bandsignal.Length; i += 4)
{
bandsignal[i] = envelope[i / 2] * sine;
}
}
var filterband = SpectrogramUtils.padded_FFT(ref bandsignal);
for (int i = 0; i < filterband.Length; ++i)
{
double x = (double)i / filterband.Length;
// normalized blackman window antiderivative
filterband[i] *= x - ((0.5 / (2.0 * Math.PI)) * Math.Sin(2.0 * Math.PI * x) + (0.08 / (4.0 * Math.PI)) * Math.Sin(4.0 * Math.PI * x) / 0.42);
}
//Console.Out.WriteLine("Spectrum size: {0}", spectrum.Length);
//std::cout << bandidx << ". filterband size: " << filterband.Length << "; start: " << filterbank->GetBand(bandidx).first <<"; end: " << filterbank->GetBand(bandidx).second << "\n";
double center = filterbank.GetCenter(bandidx);
double offset = Math.Max((double)0, center - filterband.Length / 2);
//Console.Out.WriteLine("Offset: {0} = {1} hz", offset, offset/filterscale);
for (int i = 0; i < filterband.Length; ++i)
{
int spectrumIndex = (int)(offset + i);
if (spectrumIndex > 0 && spectrumIndex < spectrum.Length)
{
spectrum[spectrumIndex] += filterband[i];
}
}
}
double[] @out = SpectrogramUtils.padded_IFFT(ref spectrum);
Console.Out.WriteLine("Samples: {0} -> {1}", @out.Length, samples);
SpectrogramUtils.NormalizeSignal(ref @out);
return(@out);
}
}