comp_s.m

linear time－frequency toolbox

function f=comp_s(self,c,dorect,callfun,Ls)
%COMP_S  Synthesis transform, rectangular layout
%  Usage: f=comp_s(tfr,c,dorect,callfun)
%         f=comp_s(tfr,c,dorect,callfun,Ls)
%
%   Input parameters:
%         tfr   : Time/frequency representation handle.
%         c     : Array of coefficients.
%         Ls    : length of signal.
%   Output parameters:
%         f     : Signal.
%
%   COMP_S(tfr,c) computes the synthesis transform of the coefficients c as
%   speficied by tfr.
%
%   COMP_S(tfr,c,Ls) does as above but cuts or extends f to length Ls.
%
%   SEE ALSO:  TFR_CREATE, TFR_AR, TFR_CLEAR

global TF_STORAGE;

% Verify that TF_STORAGE has been initialized
if prod(size(TF_STORAGE))==0
  error([callfun, 'Please run tfr_init to obtain a valid handle.']);
end;

% Easy references
a=TF_STORAGE.data{self}.a;
M=TF_STORAGE.data{self}.M;
R=TF_STORAGE.data{self}.R;
dgtinfo=TF_STORAGE.data{self}.dgtinfo;

% Determine parameters from shape of input coefficients.
if dorect

  switch dgtinfo.tt
    case {'dwilt','dwiltii'}
      N=size(c,2)*2;
    otherwise
      N=size(c,2);
  end;
  
  L=N*a;
  
  winpos=assert_winready(self,L,2,1,0,callfun);

  wininfo=TF_STORAGE.data{self}.w{winpos};

  % We are doing multiwindow.
  % third dimension is no. of window.
  % fourth dimension is no. of signal.
  if R>1
    W=size(c,4);
    if size(c,3) ~= dgtinfo.R
      error('TFR_SR: size of input array does not fit no. of windows in multiwindow.');
    end;
    % Number of signal times number of windows. These are treated together.
    WR=W*R;  
  else
    W=size(c,3);
    WR=W;
  end;

  c=reshape(c,M*N*wininfo.R,W);
else
  
  MNR=size(c,1);
  W=size(c,2);
  N=MNR/R/M;
  WR=W*R;

  if rem(N,1)~=0
    error([callfun, 'Shape of array does not fit the transform.'])
  end;

  L=a*N;

  winpos=assert_winready(self,L,2,1,0,callfun);
  
  wininfo=TF_STORAGE.data{self}.w{winpos};

end;

L_dgt=L*dgtinfo.Lmul;
a_dgt=dgtinfo.a;
M_dgt=dgtinfo.M;
N_dgt=L_dgt/a_dgt;



% pre-process if not doing a dgt.
if ~strcmp(dgtinfo.tt(1:3),'dgt')
  c=feval(['comp_i',dgtinfo.tt],c,a,M);
else
  c=reshape(c,M,N*R*W);
end;

% Pre-process if c_t is different from 0.
if (dgtinfo.c_t~=0)
  halfmod=repmat(exp(2*pi*i*dgtinfo.c_t*((0:M_dgt-1)+dgtinfo.c_f).'/M_dgt),1,N_dgt*WR);

  % The following is necessary because REPMAT does not work for
  % 3D arrays.
  halfmod=reshape(halfmod,M_dgt,N_dgt,WR);
    
  c=c.*halfmod;
end;

% Eventual phaselocking
if TF_STORAGE.data{self}.phaselock
  c=reshape(c,M_dgt,N_dgt*WR);
  c=iphaselock(c,a_dgt);
  c=reshape(c,M_dgt,N_dgt,WR);
end;

% Do the DGT part.
if abs(wininfo.Lwin)==L
  % Do full-window algorithm.
  % Apply ifft to the coefficients.
  c=ifft(c)*sqrt(M_dgt);
  
  % Get the factorization of the window.
  % Call the computational subroutine.
  % Recover from the factorization
  gf = TF_STORAGE.data{self}.w{winpos}.gf;

  f = comp_idgt_fw(c,gf,L_dgt,a_dgt,M_dgt);
  
else
  % Do filter bank algorithm.
  % Call the computational subroutine.
  f=comp_idgt_fb(reshape(c,M*N,WR),g,a,M);
  
end;

% Postprocess to handle c_f different from 0.
if (dgtinfo.c_f~=0)
  halfmod=exp(2*pi*i*dgtinfo.c_f*(0:L_dgt-1).'/M_dgt);
  f=f.*repmat(halfmod,1,WR);
end;

if dgtinfo.Lmul==2
  f=f(1:L,:);
end;


% Cut or extend f to the correct length, if desired.
if Ls>-1
  f=postpad(f,Ls);
else
  Ls=L;
end;

wasrow=0;
f=comp_sigreshape_post(f,Ls,wasrow,[0; W]);