public Bitmap Draw(double[] samples)
{
int width = samples.Length / _nfft;
int height = _nfft / 2;
var bmp = new FastBitmap(new Bitmap(width, height));
bmp.LockImage();
for (int x = 0; x < width; x++)
{
// read a segment of the recorded signal
for (int i = 0; i < _nfft; i++)
{
_segment[i] = samples[x * _nfft + i] * _window[i];
}
// transform to the frequency domain
_fft.ComputeForward(_segment);
// compute the magnitude of the spectrum
MagnitudeSpectrum(_segment, _magnitude);
// draw
for (int y = 0; y < height; y++)
{
int colorIndex = _mapper.Map(_magnitude[y]);
bmp.SetPixel(x, height - y - 1, _palette[colorIndex]);
}
}
bmp.UnlockImage();
return(bmp.GetBitmap());
}
public Bitmap Draw(double[] samples)
{
int width = samples.Length / _nfft;
int height = _nfft / 2;
var bmp = new FastBitmap(new Bitmap(width, height));
bmp.LockImage();
for (int x = 0; x < width; x++)
{
// process 2 segments offset by -1/4 and 1/4 fft size, resulting in 1/2 fft size
// window spacing (the minimum overlap to avoid discarding parts of the signal)
ProcessSegment(samples, (x * _nfft) - (x > 0 ? _nfft / 4 : 0), _magnitude1);
ProcessSegment(samples, (x * _nfft) + (x < width - 1 ? _nfft / 4 : 0), _magnitude2);
// draw
for (int y = 0; y < height; y++)
{
int colorIndex = _mapper.Map((_magnitude1[y] + _magnitude2[y]) / 2.0);
bmp.SetPixel(x, height - y - 1, _palette[colorIndex]);
}
}
bmp.UnlockImage();
return(bmp.GetBitmap());
}
public Bitmap Draw(double[] samples)
{
int width = samples.Length / _nfft;
int height = _nfft / 2;
var bmp = new FastBitmap(new Bitmap(width, height));
bmp.LockImage();
for (int x = 0; x < width; x++)
{
// process 2 segments offset by -1/4 and 1/4 fft size, resulting in 1/2 fft size
// window spacing (the minimum overlap to avoid discarding parts of the signal)
ProcessSegment(samples, (x * _nfft) - (x > 0 ? _nfft / 4 : 0), _magnitude1);
ProcessSegment(samples, (x * _nfft) + (x < width - 1 ? _nfft / 4 : 0), _magnitude2);
// draw
for (int y = 0; y < height; y++)
{
int colorIndex = _mapper.Map((_magnitude1[y] + _magnitude2[y]) / 2.0);
bmp.SetPixel(x, height - y - 1, _palette[colorIndex]);
}
}
bmp.UnlockImage();
return bmp.GetBitmap();
}
public Bitmap Draw(double[] samples)
{
int width = samples.Length / _nfft;
int height = _nfft / 2;
var bmp = new FastBitmap(new Bitmap(width, height));
bmp.LockImage();
for (int x = 0; x < width; x++)
{
// read a segment of the recorded signal
for (int i = 0; i < _nfft; i++)
{
_segment[i] = samples[x * _nfft + i] * _window[i];
}
// transform to the frequency domain
_fft.ComputeForward(_segment);
// compute the magnitude of the spectrum
MagnitudeSpectrum(_segment, _magnitude);
// draw
for (int y = 0; y < height; y++)
{
int colorIndex = _mapper.Map(_magnitude[y]);
bmp.SetPixel(x, height - y - 1, _palette[colorIndex]);
}
}
bmp.UnlockImage();
return bmp.GetBitmap();
}