using NUnit.Framework;

using System;

using System.Collections.Generic;

using System.Drawing;

using System.Drawing.Imaging;

using System.Text;

namespace Spectrogram.Tests

{

class Mel

{

[Test]

public void Test_MelSpectrogram_MelScale()

{

(double[] audio, int sampleRate) = AudioFile.ReadWAV("../../../../../data/cant-do-that-44100.wav");

int fftSize = 4096;

var sg = new SpectrogramGenerator(sampleRate, fftSize, stepSize: 500);

sg.Add(audio);

Bitmap bmpMel = sg.GetBitmapMel(250);

bmpMel.Save("../../../../../dev/graphics/halMel-MelScale.png", ImageFormat.Png);

Bitmap bmpRaw = sg.GetBitmap();

Bitmap bmpCropped = new Bitmap(bmpRaw.Width, bmpMel.Height);

using (Graphics gfx = Graphics.FromImage(bmpCropped))

{

gfx.DrawImage(bmpRaw, 0, bmpMel.Height - bmpRaw.Height);

}

bmpCropped.Save("../../../../../dev/graphics/halMel-LinearCropped.png", ImageFormat.Png);

}

[Test]

public void Test_Mel_Graph()

{

int specPoints = 4096;

double maxFreq = 50_000;

double maxMel = 2595 * Math.Log10(1 + maxFreq / 700);

Random rand = new Random(1);

double[] freq = ScottPlot.DataGen.Consecutive(specPoints, maxFreq / specPoints);

double[] power = ScottPlot.DataGen.RandomWalk(rand, specPoints, .02, .5);

var plt1 = new ScottPlot.Plot(800, 300);

plt1.AddScatter(freq, power, markerSize: 0);

int filterSize = 25;

// generate scales

double[] pointsLinear = new double[filterSize + 1];

double[] pointsMel = new double[filterSize + 1];

for (int i = 0; i < filterSize + 1; i++)

{

double thisFreq = maxFreq * i / filterSize;

double thisMel = maxMel * i / filterSize;

pointsLinear[i] = thisFreq;

pointsMel[i] = 700 * (Math.Pow(10, thisMel / 2595d) - 1);

}

// draw rectangles

double[] binStartFreqs = pointsMel;

for (int binIndex = 0; binIndex < binStartFreqs.Length - 2; binIndex++)

{

double freqLow = binStartFreqs[binIndex];

double freqCenter = binStartFreqs[binIndex + 1];

double freqHigh = binStartFreqs[binIndex + 2];

var sctr = plt1.AddScatter(

xs: new double[] { freqLow, freqCenter, freqHigh },

ys: new double[] { 0, 1, 0 },

markerSize: 0, lineWidth: 2);

int indexLow = (int)(specPoints * freqLow / maxFreq);

int indexHigh = (int)(specPoints * freqHigh / maxFreq);

int indexSpan = indexHigh - indexLow;

Console.WriteLine($"bin {binIndex}: [{freqLow} Hz - {freqHigh} Hz] = [{indexLow}:{indexHigh}]");

double binValue = 0;

double binScaleSum = 0;

for (int i = 0; i < indexSpan; i++)

{

double frac = (double)i / indexSpan;

frac = (frac < .5) ? frac * 2 : 1 - frac;

binScaleSum += frac;

binValue += power[indexLow + i] * frac;

}

binValue /= binScaleSum;

plt1.AddPoint(freqCenter, binValue, sctr.Color, 10);

}

plt1.SaveFig("mel1.png");

}

[Test]

public void Test_SaveEmpty_Throws()

{

(double[] audio, int sampleRate) = AudioFile.ReadWAV("../../../../../data/cant-do-that-44100.wav");

int fftSize = 4096;

var spec = new SpectrogramGenerator(sampleRate, fftSize, stepSize: 500);

//spec.Add(audio);

Assert.Throws<InvalidOperationException>(() => { spec.SaveImage("empty.png"); });

}

}

}