/// <summary>
/// Perform adaptive whitening on the magnitude spectrogram
/// </summary>
/// <param name="floor">floor value</param>
/// <param name="relaxation">relaxation time in seconds</param>
/// "Adaptive Whitening For Improved Real-time Audio Onset Detection"
/// Dan Stowell and Mark Plumbley
/// Proceedings of the International Computer Music Conference(ICMC), 2007
public void AW(float floor = 5, float relaxation = 10)
{
var memCoeff = (float)Math.Pow(10.0, (-6 * relaxation / _fps));
var P = _allocator.GetFloatMatrix(Spec.RowCount, Spec.ColumnCount);
//var P = Matrix<float>.Build.SameAs(Spec);
//iterate over all frames
Vector <float> spec_floor = _allocator.GetFloatVector(Spec.ColumnCount);
//var spec_floor = Vector<float>.Build.Dense(Spec.ColumnCount);
foreach (var f in Enumerable.Range(0, _frames))
{
spec_floor.Clear();
for (int i = 0; i < Spec.ColumnCount; i++)
{
spec_floor[i] = Math.Max(Spec[f, i], floor);
}
//var spec_floor = Math.Max(Spec.ToRowArrays()[f].ToList().Max(), floor);
if (f > 0)
{
for (int i = 0; i < P.ColumnCount; i++)
{
P[f, i] = Math.Max(spec_floor[i], memCoeff * P[f - 1, i]);
}
}
else
{
P.SetRow(f, spec_floor);
}
}
//adjust spec
Spec = Spec.PointwiseDivide(P);
//cleanup
_allocator.ReturnFloatMatrixStorage((MathNet.Numerics.LinearAlgebra.Storage.DenseColumnMajorMatrixStorage <float>)P.Storage);
_allocator.ReturnFloatVectorStorage((MathNet.Numerics.LinearAlgebra.Storage.DenseVectorStorage <float>)spec_floor.Storage);
}
public void Cleanup()
{
_allocator.ReturnFloatMatrixStorage((MathNet.Numerics.LinearAlgebra.Storage.DenseColumnMajorMatrixStorage <float>)Filterbank.Storage);
}
