www.pudn.com > bss_eval.zip > bss_tvproj.m

function [PY_x coeff] = bss_tvproj(x,Y,tvshape,tvstep) 
 
% compute the orthogonal projection of x onto the space of shifted windowed versions of the row(s) of Y 
% 
% Usage: [PY_x coeff] = tvproj(x,Y,tvshape,tvstep) 
% 
% Input: 
%   - x: row vector of length T corresponding to the signal to be projected, 
%   - Y: vector or matrix of length T with n_rows rows which windowed rows span the projection space. 
%   - tvshape : row vector of length V corresponding to the window applied 
%   to Y to define the projection space 
%   - tvstep  : number of samples between two adjacent windows 
% 
% Ouput: 
%   - PY_x: row vector of length T containing the orthogonal projection of 
%   x onto the range of the shifted windowed versions of the row(s) of Y. 
%   - coeff : matrix with n_rows rows and n_frames columns containing the coefficients  
%   of the projection  
% 
% Developers:  - Cedric Fevotte (cf269@cam.ac.uk) - Emmanuel Vincent 
% (vincent@ircam.fr) - Remi Gribonval (remi.gribonval@irisa.fr) 
 
% 1. Decompose Y into frames using tvshape as a window 
V        = size(tvshape,2); % the size of the window 
NOVERLAP = V-tvstep;        % convert the hop size into a number of overlapping samples 
 
[Y_frames frames_index] = bss_make_frames(Y,tvshape,NOVERLAP); % Y_frames is a 3-D array 
[n_frames V1 n_rows]= size(Y_frames); 
 
% 2. Compute the inner products between x and the frames of the row(s) of Y 
ip = zeros(n_frames,n_rows); 
for f=1:n_frames % loop on frames 
    ip(f,:) = x(frames_index(f)+(0:(V-1)) ) * reshape(Y_frames(f,:,:),V,n_rows); % columns of ip correspond to the same frame number 
end 
ip = reshape(ip,n_frames*n_rows,1); % now we want a single column vector to apply an inverse matrix to it 
 
% 3. Compute the Gram matrix, which is square of size (n_frames x n_rows) x 
% (n_frames x n_rows)  
Gram = zeros(n_frames*n_rows,n_frames*n_rows); 
for f=1:n_frames  
    for f1 = 1:n_frames 
        % locate the range of the intersection between frames 
        first = max(frames_index(f),frames_index(f1)); 
        last  = min(frames_index(f),frames_index(f1))+V-1; 
        % if the intersection is non empty, fill it 
        if (first <= last) 
            trange = (first:last)-frames_index(f)+1; 
            trange1= (first:last)-frames_index(f1)+1; 
            Gram((f-1)*n_rows+(1:n_rows),(f1-1)*n_rows+(1:n_rows)) = reshape(Y_frames(f,trange,:),length(trange),n_rows)'*reshape(Y_frames(f1,trange1,:),length(trange1),n_rows); % shall we reshape Y_frames ???? 
        end 
    end 
end 
 
% 4. Apply the inverse of the Gram matrix to ip to get coeff 
coeff = Gram\ip; 
coeff = reshape(coeff,n_frames,n_rows); 
% 4.  Reconstruct using coefficients alpha 
PY_x = zeros(size(x)); 
 
for f=1:n_frames 
    PY_x(frames_index(f)+(0:(V-1))) = PY_x(frames_index(f)+(0:(V-1))) + coeff(f,:)*reshape(Y_frames(f,:,:),V,n_rows)'; 
end