[c77b15]: blockproc / blocksyn.m  Maximize  Restore  History

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function fhat = blocksyn( F, c , Lb)
%BLOCKSYN Blockwise synthesis interface
% Usage: blocksyn(F, c, Lb)
%
% Input parameters:
% F : Frame object.
% c : Coefficients of a block.
% Output parameters:
% fhat : Reconstructed block.
%
% `c=blocksyn(F, c, Lb)` reconstructs block `fhat` from coefficients `c`
% using frame defined by `F`.
if nargin<3
error('%s: Too few input parameters.',upper(mfilename));
end;
if ~isstruct(F)
error('%s: First agument must be a frame definition structure.',upper(mfilename));
end;
% Next block index start (from a global point of view, starting with zero)
nextSb = block_interface('getPos');
% Block index start (from a global point of view, starting with zero)
Sb = nextSb-Lb;
switch(F.type)
case 'fwt'
J = F.J;
w = F.g;
m = numel(w.g{1}.h);
a = w.a(1);
blocksize = a^J;
r = (a^J-1)/(a-1)*(m-1);
Lbrec = (floor(nextSb/blocksize) - floor(Sb/blocksize))*blocksize;
rSb = (a^J-1)/(a-1)*(m-a) + mod(Sb,a^J);
over = r - rSb;
f = block_ifwt(c,w,J,Lbrec);
ol = loadOverlap(r-mod(Sb, a^J));
olLen = size(ol,1);
f(1:olLen-over,:) = f(1:olLen-over,:) + ol(1+over:end,:);
f = [ol(1:over,:);f];
storeOverlap(f,r-mod(nextSb, a^J));
fhat = f(1:Lb,:);
otherwise
% General processing
% Equal block length assumtion
% Reconstruct
f = frsyn(F,c);
% Result should not be longer than 2*Lb
f = f(1:2*Lb,:);
% Load and add overlap (first half)
ol = loadOverlap(Lb);
olLen = size(ol,1);
f(1:olLen,:) = f(1:olLen,:) + ol;
% Store overlap (second half)
storeOverlap(f,Lb);
% Return first half
fhat = f(1:Lb,:);
end
function overlap = loadOverlap(L)
overlap = block_interface('getSynOverlap');
if isempty(overlap)
overlap = zeros(L,size(c,2));
end
Lo = size(overlap,1);
if nargin<1
L = Lo;
end
if L>Lo
error('%s: Required more samples than stored.',upper(mfilename));
end
overlap = overlap(end-L+1:end,:);
end
function storeOverlap(fext,L)
if L>size(fext)
error('%s: Required more samples.',upper(mfilename));
end
block_interface('setSynOverlap',fext(end-L+1:end,:));
end
end

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