static IEnumerable<IEnumerable<float>> UpSample(WaveReader reader, int windowSize)
{
var fft = new MathNet.Numerics.Transformations.ComplexFourierTransformation ();
var determineVolumeSource = new Complex[]
{
new Complex(1, 0),
new Complex(1, 0),
new Complex(1, 0),
new Complex(1, 0),
};
fft.TransformForward(determineVolumeSource);
var determineVolumeDestination = new Complex[windowSize];
determineVolumeDestination[0] = determineVolumeSource[0];
for (var sampleCtr = 1; sampleCtr < windowSize; sampleCtr++)
determineVolumeDestination[sampleCtr] = Complex.FromModulusArgument(0,0);
fft.TransformBackward(determineVolumeDestination);
var multiplier = determineVolumeDestination[0].Real;
var sampleQueue = new Queue<float[]>();
for (var sampleCtr = 0; sampleCtr < 2; sampleCtr++)
sampleQueue.Enqueue(new float[reader.NumChannels]);
foreach (var samples in reader.ReadAllSamples_Float().Select(s => s.ToArray()))
{
sampleQueue.Enqueue(samples);
if (sampleQueue.Count == 4)
{
var expanded = new float[windowSize / 2][];
for (var ctr = 0; ctr < windowSize / 2; ctr++)
expanded[ctr] = new float[reader.NumChannels];
for (var channelCtr = 0; channelCtr < reader.NumChannels; channelCtr++)
{
var samplesToTransform = sampleQueue.Select(s => new Complex (s[channelCtr], 0)).ToArray();
fft.TransformForward (samplesToTransform);
var samplesToTransformBack = new Complex[windowSize];
samplesToTransformBack[0] = samplesToTransform[0];
samplesToTransformBack[1] = samplesToTransform[1];
samplesToTransformBack[1].Modulus /= 2;
samplesToTransformBack[samplesToTransformBack.Length - 1] = samplesToTransform[1];
samplesToTransformBack[samplesToTransformBack.Length - 1].Modulus /= 2;
samplesToTransformBack[samplesToTransformBack.Length - 1].Argument *= -1;
for (var ctr = 2; ctr < samplesToTransformBack.Length - 1; ctr++)
samplesToTransformBack[ctr] = Complex.FromModulusArgument(0, 0);
fft.TransformBackward(samplesToTransformBack);
for (var ctr = 0; ctr < windowSize / 2; ctr++)
expanded[ctr][channelCtr] = Convert.ToSingle(samplesToTransformBack[ctr + windowSize / 4].Real / multiplier);
}
foreach (var simplified in expanded)
yield return simplified;
sampleQueue.Dequeue();
sampleQueue.Dequeue();
}
}
}
public static IEnumerable<float[]> DownSample(IEnumerable<float[]> samplesEnumerator, int numChannels, int windowSize, Action<float[]> highSampleCallback)
{
var fft = new MathNet.Numerics.Transformations.ComplexFourierTransformation ();
var determineVolumeSource = new Complex[windowSize];
for (var sampleCtr = 0; sampleCtr < windowSize; sampleCtr++)
determineVolumeSource[sampleCtr] = new Complex(1, 0);
fft.TransformForward(determineVolumeSource);
var determineVolumeDestination = new Complex[]
{
determineVolumeSource[0],
Complex.FromModulusArgument(0,0),
Complex.FromModulusArgument(0,0),
Complex.FromModulusArgument(0,0)
};
fft.TransformBackward(determineVolumeDestination);
var dcMultiplier = determineVolumeDestination[0].Modulus;
var ratio = (1d / Convert.ToDouble(windowSize)) * 2d * Math.PI;
for (var sampleCtr = 0; sampleCtr < windowSize; sampleCtr++)
{
var sampleCtrDouble = Convert.ToDouble(sampleCtr);
determineVolumeSource[sampleCtr] = new Complex(Math.Cos(sampleCtrDouble * ratio), 0);
}
fft.TransformForward(determineVolumeSource);
determineVolumeDestination = new Complex[]
{
Complex.FromModulusArgument(0,0),
determineVolumeSource[1],
Complex.FromModulusArgument(0,0),
determineVolumeSource[determineVolumeSource.Length - 1],
};
fft.TransformBackward(determineVolumeDestination);
var midMultiplier = determineVolumeDestination.Select(s => s.Modulus).Max();
/*// This only works when windowsize is 8
for (var sampleCtr = 0; sampleCtr < windowSize; sampleCtr++)
{
var abs = sampleCtr % 2 == 1 ? 1 : 0;
var sign = sampleCtr % 4 > 1 ? 1 : -1;
determineVolumeSource[sampleCtr] = new Complex(abs * sign, 0);
}*/
ratio = (1d / Convert.ToDouble(windowSize)) * 4d * Math.PI;
for (var sampleCtr = 0; sampleCtr < windowSize; sampleCtr++)
{
var sampleCtrDouble = Convert.ToDouble(sampleCtr);
determineVolumeSource[sampleCtr] = new Complex(Math.Cos(sampleCtrDouble * ratio), 0);
}
fft.TransformForward(determineVolumeSource);
determineVolumeDestination = new Complex[]
{
Complex.FromModulusArgument(0,0),
Complex.FromModulusArgument(0,0),
determineVolumeSource[2],
Complex.FromModulusArgument(0,0),
};
fft.TransformBackward(determineVolumeDestination);
var highMultiplier = determineVolumeDestination.Select(s => s.Modulus).Max();
var sampleQueue = new Queue<float[]>();
for (var sampleCtr = 0; sampleCtr < windowSize / 4; sampleCtr++)
sampleQueue.Enqueue(new float[numChannels]);
var maxOriginalSample = 0.0;
var maxLowFrequencySample = 0.0;
using (var sampleEnumerator = samplesEnumerator.GetEnumerator())
{
int samplesFromSource;
do
{
samplesFromSource = 0;
while (sampleQueue.Count < windowSize)
{
if (sampleEnumerator.MoveNext())
{
sampleQueue.Enqueue(sampleEnumerator.Current.ToArray());
samplesFromSource++;
}
else
sampleQueue.Enqueue(new float[numChannels]);
}
var simplified = new float[][]
{
new float[numChannels],
new float[numChannels]
};
var filtered = new float[windowSize / 2][];
for (var sampleCtr = 0; sampleCtr < windowSize / 2; sampleCtr++)
filtered[sampleCtr] = new float[numChannels];
for (var channelCtr = 0; channelCtr < numChannels; channelCtr++)
{
maxOriginalSample = Math.Max(
maxOriginalSample,
sampleQueue.Select(s => Math.Abs(s[channelCtr])).Max());
var samplesToTransform = sampleQueue.Select (s => new Complex (s [channelCtr], 0)).ToArray ();
fft.TransformForward (samplesToTransform);
var samplesToTransformBack = new Complex[]
{
samplesToTransform[0],
samplesToTransform[1],
samplesToTransform[2],
samplesToTransform[samplesToTransform.Length - 1]
};
samplesToTransformBack[0].Modulus /= dcMultiplier;
samplesToTransformBack[1].Modulus /= midMultiplier;
samplesToTransformBack[2].Modulus /= highMultiplier;
samplesToTransformBack[3].Modulus /= midMultiplier;
fft.TransformBackward(samplesToTransformBack);
simplified[0][channelCtr] = Convert.ToSingle(samplesToTransformBack[1].Real);
simplified[1][channelCtr] = Convert.ToSingle(samplesToTransformBack[2].Real);
for (var filterCtr = 3; filterCtr < (samplesToTransform.Length - 1); filterCtr++)
samplesToTransform[filterCtr] = Complex.FromModulusArgument(0, 0);
fft.TransformBackward(samplesToTransform);
for (var sampleCtr = 0; sampleCtr < windowSize / 2; sampleCtr++)
filtered[sampleCtr][channelCtr] = Convert.ToSingle(samplesToTransform[sampleCtr + (windowSize / 4)].Real);
}
maxLowFrequencySample = Math.Max(
maxLowFrequencySample,
simplified.SelectMany(s => s).Select(Math.Abs).Max());
foreach (var samples in simplified)
yield return samples;
foreach (var samples in filtered)
highSampleCallback(samples);
while (sampleQueue.Count > windowSize / 2)
sampleQueue.Dequeue();
} while (samplesFromSource > (windowSize / 4));
}
/*Console.WriteLine("Loudest sample in source: {0}", maxOriginalSample);
Console.WriteLine("Loudest sample in low frequency: {0}", maxLowFrequencySample);
//Console.WriteLine("Loudest sample in high frequency: {0}", maxHighFrequencySample);
Console.WriteLine();*/
}