/// <summary>
/// Create log-spectrogram (spaced according to manager's parameters)
/// </summary>
/// <param name = "proxy">Proxy used in generating the spectrogram</param>
/// <param name = "filename">Filename to be processed</param>
/// <param name = "milliseconds">Milliseconds to be analyzed</param>
/// <param name = "startmilliseconds">Starting point</param>
/// <returns>Logarithmically spaced bins within the power spectrum</returns>
public float[][] CreateLogSpectrogram(IAudio proxy, string filename, int milliseconds, int startmilliseconds)
{
//read 5512 Hz, Mono, PCM, with a specific proxy
float[] samples = proxy.ReadMonoFromFile(filename, SampleRate, milliseconds, startmilliseconds);
//NormalizeInPlace(samples);
int overlap = Overlap;
int fftWindowsSize = WdftSize;
double[] windowArray = FFTWindowFunctions.GetWindowFunction(FFTWindowFunctions.HANNING, fftWindowsSize);
int width = (samples.Length - fftWindowsSize) / overlap; /*width of the image*/
float[][] frames = new float[width][];
float[] complexSignal = new float[2 * fftWindowsSize]; /*even - Re, odd - Img*/
for (int i = 0; i < width; i++)
{
//take 371 ms each 11.6 ms (2048 samples each 64 samples)
for (int j = 0; j < fftWindowsSize /*2048*/; j++)
{
// Weight by Hann Window
complexSignal[2 * j] = (float)(windowArray[j] * samples[i * overlap + j]);
//complexSignal[2*j] = (float) (_windowArray[j]*samples[i*overlap + j]); /*Weight by Hann Window*/
complexSignal[2 * j + 1] = 0;
}
//FFT transform for gathering the spectrum
Fourier.FFT(complexSignal, fftWindowsSize, FourierDirection.Forward);
frames[i] = ExtractLogBins(complexSignal);
}
return(frames);
}
/// <summary>
/// Create spectrogram of the input file
/// </summary>
/// <param name = "proxy">Proxy used to read from file</param>
/// <param name = "filename">Filename</param>
/// <param name = "milliseconds">Milliseconds to process</param>
/// <param name = "startmilliseconds">Starting point of the processing</param>
/// <returns>Spectrogram</returns>
public float[][] CreateSpectrogram(IAudio proxy, string filename, int milliseconds, int startmilliseconds, bool doNormalise)
{
//read 5512 Hz, Mono, PCM, with a specific proxy
float[] samples = proxy.ReadMonoFromFile(filename, SampleRate, milliseconds, startmilliseconds);
if (doNormalise)
{
NormalizeInPlace(samples);
}
int overlap = Overlap;
int fftWindowsSize = WdftSize; // aka N = FFT Length
double[] windowArray = FFTWindowFunctions.GetWindowFunction(FFTWindowFunctions.HANNING, fftWindowsSize);
int width = (samples.Length - fftWindowsSize) / overlap; /*width of the image*/
float[][] frames = new float[width][];
float[] complexSignal = new float[2 * fftWindowsSize]; /*even - Re, odd - Img*/
for (int i = 0; i < width; i++)
{
//take 371 ms each 11.6 ms (2048 samples each 64 samples)
// apply Hanning Window
for (int j = 0; j < fftWindowsSize /*2048*/; j++)
{
// Weight by Hann Window
complexSignal[2 * j] = (float)(windowArray[j] * samples[i * overlap + j]);
//complexSignal[2*j] = (float) ((4.0/(fftWindowsSize - 1)) * windowArray[j]*samples[i*overlap + j]); /*Weight by Hann Window*/
complexSignal[2 * j + 1] = 0; // need to clear out as fft modifies buffer
}
//FFT transform for gathering the spectrum
Fourier.FFT(complexSignal, fftWindowsSize, FourierDirection.Forward);
float[] band = new float[fftWindowsSize / 2 + 1];
for (int j = 0; j < fftWindowsSize / 2 + 1; j++)
{
double re = complexSignal[2 * j];
double img = complexSignal[2 * j + 1];
//double img = 0.0; // TODO: Zero out the imaginary component (phase) ? / need to clear out as fft modifies buffer
band[j] = (float)Math.Sqrt(re * re + img * img);
}
frames[i] = band;
}
return(frames);
}
