public static Bitmap BitmapFromFFTs(float[][] ffts, Settings.DisplaySettings displaySettings)
{
if (ffts == null || ffts.Length == 0)
{
throw new ArgumentException("ffts must contain float arrays");
}
Bitmap bmp = new Bitmap(ffts.Length, displaySettings.height, PixelFormat.Format8bppIndexed);
ApplyColormap(bmp, displaySettings.colormap);
var rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
BitmapData bitmapData = bmp.LockBits(rect, ImageLockMode.ReadOnly, bmp.PixelFormat);
byte[] pixels = new byte[bitmapData.Stride * bmp.Height];
for (int col = 0; col < bmp.Width; col++)
{
if (col >= bmp.Width)
{
continue;
}
if (col == displaySettings.highlightColumn)
{
for (int row = 0; row < bmp.Height; row++)
{
int bytePosition = (bmp.Height - 1 - row) * bitmapData.Stride + col;
pixels[bytePosition] = 255;
}
continue;
}
if (ffts[col] == null)
{
continue;
}
for (int row = 0; row < bmp.Height; row++)
{
int bytePosition = (bmp.Height - 1 - row) * bitmapData.Stride + col;
float pixelValue;
pixelValue = ffts[col][row + displaySettings.pixelLower];
if (displaySettings.decibels)
{
pixelValue = (float)(Math.Log10(pixelValue) * 20);
}
pixelValue = (pixelValue * displaySettings.brightness);
pixelValue = Math.Max(0, pixelValue);
pixelValue = Math.Min(255, pixelValue);
pixels[bytePosition] = (byte)(pixelValue);
}
}
Marshal.Copy(pixels, 0, bitmapData.Scan0, pixels.Length);
bmp.UnlockBits(bitmapData);
return(bmp);
}
public Spectrogram(int sampleRate = 8000, int fftSize = 1024, int? step = null)
{
if (step == null)
step = sampleRate;
fftSettings = new Settings.FftSettings(sampleRate, fftSize, (int)step);
displaySettings = new Settings.DisplaySettings();
displaySettings.fftResolution = fftSettings.fftResolution;
displaySettings.freqHigh = fftSettings.maxFreq;
}