Dimitrios@0: function spCQT = cell2sparse(Xcq,octaves,bins,firstcenter,atomHOP,atomNr)
Dimitrios@0: %Generates a sparse matrix containing the CQT coefficients (rasterized).
Dimitrios@0: %
Dimitrios@0: %The sparse matrix representation of the CQT coefficients contains all
Dimitrios@0: %computed coefficients at the corresponding time-frequency location
Dimitrios@0: %(similar to a spectrogram). For lower frequencies this means, that
Dimitrios@0: %each coefficient is followed by zeros stemming from the fact, that the time
Dimitrios@0: %resolution for lower frequencies decreases as the frequency resolution
Dimitrios@0: %increases. Due to the design of the CQT kernel, however, the coefficients
Dimitrios@0: %of different octaves are synchronised, meaning that for the second highest
Dimitrios@0: %octave each coefficient is followed by one zero, for the next octave down
Dimitrios@0: %two zeros are inserted, for the next octave four zeros are inserted and so
Dimitrios@0: %on.
Dimitrios@0: %
Dimitrios@0: %INPUT:
Dimitrios@0: %   Xcq         ... Cell array consisting of all coefficients for all octaves
Dimitrios@0: %   octaves     ... Number of octaves processed
Dimitrios@0: %   bins        ... Number of bins per octave
Dimitrios@0: %   firstcenter ... Location of the leftmost atom-stack in the temporal
Dimitrios@0: %                   kernel
Dimitrios@0: %   atomHOP     ... Spacing of two consecutive atom stacks
Dimitrios@0: %   atomNr      ... Number of atoms per bin within the kernel
Dimitrios@0: %
Dimitrios@0: %Christian Schörkhuber, Anssi Klapuri 2010-06
Dimitrios@0: 
Dimitrios@0: if 0
Dimitrios@0: %% this version has big memory consumption but is very fast
Dimitrios@0:     emptyHops = firstcenter/atomHOP;
Dimitrios@0:     drop = emptyHops*2^(octaves-1)-emptyHops; %distance between first value in highest octave and first value in lowest octave
Dimitrios@0:     spCQT = zeros(bins*octaves,size(Xcq{1},2)*atomNr-drop);
Dimitrios@0: 
Dimitrios@0:     for i=1:octaves
Dimitrios@0:         drop = emptyHops*2^(octaves-i)-emptyHops; %first coefficients of all octaves have to be in synchrony
Dimitrios@0:         X = Xcq{i}; 
Dimitrios@0:         if  atomNr > 1 %more than one atom per bin --> reshape
Dimitrios@0:             Xoct = zeros(bins,atomNr*size(X,2)-drop);
Dimitrios@0:             for u=1:bins %reshape to continous windows for each bin (for the case of several wins per frame)
Dimitrios@0:                octX_bin = X((u-1)*atomNr+1:u*atomNr,:);
Dimitrios@0:                Xcont = reshape(octX_bin,1,size(octX_bin,1)*size(octX_bin,2));
Dimitrios@0:                Xoct(u,:) = Xcont(1+drop:end);
Dimitrios@0:             end
Dimitrios@0:             X = Xoct;
Dimitrios@0:         else
Dimitrios@0:             X = X(:,1+drop:end);
Dimitrios@0:         end
Dimitrios@0:         binVec = bins*octaves-bins*i+1:bins*octaves-bins*(i-1);
Dimitrios@0:         spCQT(binVec,1:2^(i-1):size(X,2)*2^(i-1)) = X;
Dimitrios@0: 
Dimitrios@0:     end
Dimitrios@0:     spCQT = sparse(spCQT); %storing as sparse matrix at the end is the fastest way. Big memory consumption though!
Dimitrios@0: 
Dimitrios@0: else
Dimitrios@0: %% this version uses less memory but is noticable slower
Dimitrios@0:     emptyHops = firstcenter/atomHOP;
Dimitrios@0:     drops = emptyHops*2.^(octaves-(1:octaves))-emptyHops;
Dimitrios@0:     len = max(((atomNr*cellfun('size',Xcq,2)-drops).*2.^(0:octaves-1))); %number of columns of output matrix
Dimitrios@0:     spCQT = [];
Dimitrios@0: 
Dimitrios@0:     for i=octaves:-1:1
Dimitrios@0:         drop = emptyHops*2^(octaves-i)-emptyHops; %first coefficients of all octaves have to be in synchrony
Dimitrios@0:         X = Xcq{i}; 
Dimitrios@0:         if  atomNr > 1 %more than one atom per bin --> reshape
Dimitrios@0:             Xoct = zeros(bins,atomNr*size(X,2)-drop);
Dimitrios@0:             for u=1:bins %reshape to continous windows for each bin (for the case of several wins per frame)
Dimitrios@0:                octX_bin = X((u-1)*atomNr+1:u*atomNr,:);
Dimitrios@0:                Xcont = reshape(octX_bin,1,size(octX_bin,1)*size(octX_bin,2));
Dimitrios@0:                Xoct(u,:) = Xcont(1+drop:end);
Dimitrios@0:             end
Dimitrios@0:             X = Xoct;
Dimitrios@0:         else
Dimitrios@0:             X = X(:,1+drop:end);
Dimitrios@0:         end
Dimitrios@0:         X = upsample(X.',2^(i-1)).';
Dimitrios@0:         X = [X zeros(bins,len-size(X,2))];
Dimitrios@0:         spCQT = sparse([spCQT; X]);  
Dimitrios@0:     end
Dimitrios@0: 
Dimitrios@0: end