public static void TestSpectrograms()
{
const int fftWindowSize = 4096;
const int overlap = 2048;
var data = AudioUtilsNAudio.GenerateAudioTestData(44100, 10);
double[][] spec1 = FFTUtils.CreateSpectrogramLomont(data, fftWindowSize, overlap);
var spec1M = new Matrix(spec1);
spec1M.WriteCSV("spec_lomont.csv");
double[][] spec2 = FFTUtils.CreateSpectrogramExocortex(data, fftWindowSize, overlap);
var spec2M = new Matrix(spec2);
spec2M.WriteCSV("spec_exocortex.csv");
Assert.That(spec2, Is.EqualTo(spec1).AsCollection.Within(0.001), "fail at [0]");
double[][] spec3 = FFTUtils.CreateSpectrogramFFTW(data, fftWindowSize, overlap);
var spec3M = new Matrix(spec3);
spec3M.WriteCSV("spec_fftw.csv");
//Assert.That(spec3, Is.EqualTo(spec1).AsCollection.Within(0.001), "fail at [0]");
double[][] spec4 = FFTUtils.CreateSpectrogramFFTWLIB(data, fftWindowSize, overlap);
var spec4M = new Matrix(spec4);
spec4M.WriteCSV("spec_fftwlib.csv");
//Assert.That(spec4, Is.EqualTo(spec1).AsCollection.Within(0.001), "fail at [0]");
double[][] spec5 = FFTUtils.CreateSpectrogramFFTWLIB_INPLACE(data, fftWindowSize, overlap);
var spec5M = new Matrix(spec5);
spec5M.WriteCSV("spec_fftwlib_inplace.csv");
//Assert.That(spec5, Is.EqualTo(spec1).AsCollection.Within(0.001), "fail at [0]");
}
public void TestFFTAudioMatrixMethod()
{
// harmor_HQ.bmp = 1645 (width) x 511 (height) 32 bit
// test variables
const string outputDirectoryFilePath = "test";
var audioSystem = BassProxy.Instance;
// 0. Get Audio Data
float[] audioSamples = BassProxy.ReadMonoFromFile(WAVE_INPUT_FILEPATH, SAMPLING_RATE);
int width = 1645;
//int width = (audioSamples.Length - WINDOW_SIZE)/ OVERLAP;
int OVERLAP = (int)((double)(audioSamples.Length - WINDOW_SIZE) / (double)width);
// 1. Explode samples to the range of 16 bit shorts (–32,768 to 32,767)
// Matlab multiplies with 2^15 (32768)
// e.g. if( max(abs(speech))<=1 ), speech = speech * 2^15; end;
MathUtils.Multiply(ref audioSamples, AUDIO_MULTIPLIER);
// zero pad if the audio file is too short to perform a fft
if (audioSamples.Length < (WINDOW_SIZE + OVERLAP))
{
int lenNew = WINDOW_SIZE + OVERLAP;
Array.Resize <float>(ref audioSamples, lenNew);
}
// 2. Windowing
// 3. FFT
#region Windowing and FFT
var stft = new STFT(FFTWindowType.HANNING, WINDOW_SIZE, OVERLAP);
var stftdata = stft.Apply(audioSamples);
// same as specgram(audio*32768, 2048, 44100, hanning(2048), 1024);
stftdata.DrawMatrixImageLogValues(outputDirectoryFilePath + "_specgram.png", true, false, -1, -1, false);
var spect2 = FFTUtils.CreateSpectrogramFFTW(audioSamples, WINDOW_SIZE, OVERLAP);
var stftdata2 = new Matrix(spect2).Transpose();
// same as specgram(audio*32768, 2048, 44100, hanning(2048), 1024);
stftdata2.DrawMatrixImageLogValues(outputDirectoryFilePath + "_specgram2.png", true, false, -1, -1, false);
var spect3 = FFTUtils.CreateSpectrogramLomont(audioSamples, WINDOW_SIZE, OVERLAP);
var stftdata3 = new Matrix(spect3).Transpose();
// same as specgram(audio*32768, 2048, 44100, hanning(2048), 1024);
stftdata3.DrawMatrixImageLogValues(outputDirectoryFilePath + "_specgram3.png", true, false, -1, -1, false);
#endregion
// the matrix are too different so comparing them always fails!
//Assert.That(stftdata2, Is.EqualTo(stftdata3).AsCollection.Within(0.001), "fail at [0]");
#region Inverse FFT
// Perform inverse stft as well
double[] audiodata_inverse_stft = stft.InverseStft(stftdata);
// divide or normalize
//MathUtils.Divide(ref audiodata_inverse_stft, AUDIO_MULTIPLIER);
MathUtils.Normalize(ref audiodata_inverse_stft);
Export.DrawGraph(audiodata_inverse_stft, outputDirectoryFilePath + "_audiodata_inverse_stft.png");
float[] audiodata_inverse_float = MathUtils.DoubleToFloat(audiodata_inverse_stft);
BassProxy.SaveFile(audiodata_inverse_float, outputDirectoryFilePath + "_inverse_stft.wav", 1, SAMPLING_RATE, 32);
#endregion
Assert.Pass("This test was succesful.");
}
