TITLE:: FluidBufNNDSVD
summary:: Non-Negative Double Singular Value Decomposition on a Buffer
categories:: FluidManipulation
related:: Classes/FluidBufNMF

DESCRIPTION::
Find Initial Bases and Activations for FluidBufNMF via Non-Negative Double Singular Value Decomposition .

See http://nimfa.biolab.si/nimfa.methods.seeding.nndsvd.html

CLASSMETHODS::

METHOD:: process
This is the method that calls for the decomposition to be calculated on a given source buffer.

ARGUMENT:: server
The server on which the buffers to be processed are allocated.

ARGUMENT:: source
The index of the buffer to use as the source material to be decomposed through the NMF process. The different channels of multichannel buffers will be processing sequentially.

ARGUMENT:: bases
The index of the buffer where the different bases will be written to and/or read from: the behaviour is set in the following argument.

ARGUMENT:: activations
The index of the buffer where the different activations will be written to and/or read from: the behaviour is set in the following argument.

ARGUMENT:: minComponents
Minimum number of estimated components

ARGUMENT:: maxComponents
Maximum number of estimated components

ARGUMENT:: coverage
Fraction (0 to 1) of information preserved in the decomposition

ARGUMENT:: method
The method used for the decomposition. Options are:

table::
## 0 || NMF-SVD || faster
## 1 || NNDSVDar || more accurate, fill in the zero elements with random values
## 2 || NNDSVDa || fill in the zero elements with the average
## 3 || NNDSVD || leave zero elements as zero, works better for sparse spectrograms
::

ARGUMENT:: windowSize
	The window size. As spectral differencing relies on spectral frames, we need to decide what precision we give it spectrally and temporally, in line with Gabor Uncertainty principles. http://www.subsurfwiki.org/wiki/Gabor_uncertainty

ARGUMENT:: hopSize
	The window hop size. As sinusoidal estimation relies on spectral frames, we need to move the window forward. It can be any size but low overlap will create audible artefacts. The -1 default value will default to half of windowSize (overlap of 2).

ARGUMENT:: fftSize
	The inner FFT/IFFT size. It should be at least 4 samples long, at least the size of the window, and a power of 2. Making it larger allows an oversampling of the spectral precision. The -1 default value will use the next power of 2 equal or above the highest of windowSize and (bandwidth - 1) * 2.

ARGUMENT:: action
	A Function to be evaluated once the offline process has finished and all Buffer's instance variables have been updated on the client side. The function will be passed [destination] as an argument.

INSTANCEMETHODS::

private:: synth, server

EXAMPLES::

code::
(
b = Buffer.read(s,File.realpath(FluidBufNNDSVD.class.filenameSymbol).dirname.withTrailingSlash ++ "../AudioFiles/Nicol-LoopE-M.wav");
~bases = Buffer.new(s);
~activations = Buffer.new(s);
~resynth = Buffer.new(s);
)

//how many bases do I need to decompose the buffer with 90% accuracy
FluidBufNNDSVD.process(s, b, ~bases, ~activations, coverage: 0.9, method: 1, action: {\done.postln;})

//check how many bases we are returned:
~bases.numChannels

//try the same process with less accuracy
FluidBufNNDSVD.process(s, b, ~bases, ~activations, coverage: 0.5, action: {\done.postln;})
~bases.numChannels

//use the bases to run NMF on
FluidBufNMF.process(s, b, resynth: ~resynth, bases: ~bases, activations: ~activations,actMode: 2, components: ~bases.numChannels, action: {\done.postln;})
{PlayBuf.ar(~resynth.numChannels, ~resynth)[1]}.play
}
::
