function Fo = blockframeaccel(F, Lb, varargin)
%BLOCKFRAMEACCEL Precompute structures for block processing
% Usage: F = blockframeaccel(F,Lb);
%
% F=BLOCKFRAMEACCEL(F,Lb) has to be called for each frame object prior to
% entering the main loop where BLOCKANA and BLOCKSYN are called.
% The function works entirely like FRAMEACCEL but in addition, it prepares
% structures for the processing of a consecutive stream of blocks.
%
% 'sliwin',sliwin : Slicing window. sliwin have to be a window
% of length 2Lb or a string accepted
% by the FIRWIN function. It is used only in
% the slicing window approach. The default is
% 'hann'.
%
% 'zpad',zpad : Number of zero samples the block will be padded
% after it is windowed by a slicing window. This
% does not affect the synthesis windowing.
%
% Url: http://ltfat.github.io/doc/blockproc/blockframeaccel.html
% Copyright (C) 2005-2023 Peter L. Soendergaard <peter@sonderport.dk> and others.
% This file is part of LTFAT version 2.6.0
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program. If not, see <http://www.gnu.org/licenses/>.
complainif_notenoughargs(nargin,2,'BLOCKFRAMEACCEL');
complainif_notvalidframeobj(F,'BLOCKFRAMEACCEL');
definput.flags.blockalg = {'naive','sliced','segola'};
definput.keyvals.sliwin = [];
definput.keyvals.zpad = 0;
[flags,kv]=ltfatarghelper({},definput,varargin);
isSliProp = ~isempty(kv.sliwin) || kv.zpad~=0;
assert(~(~flags.do_sliced && isSliProp),...
sprintf(['%s: Definig slicing window properties without setting the',...
' ''sliced'' flag.'], mfilename));
if flags.do_sliced
if isempty(kv.sliwin)
kv.sliwin = 'hann';
end
if ~isnumeric(kv.sliwin)
kv.sliwin = fftshift(sqrt(firwin(kv.sliwin,2*Lb)));
end
Fo = frameaccel(F,2*Lb+2*kv.zpad);
Fo.sliwin = kv.sliwin;
Fo.zpad = kv.zpad;
elseif flags.do_segola
% Determine window length without calling frameaccel
% Fo = frameaccel(F,Lb);
winLen = framefirlen(F);
if winLen==-1
error(['%s: Segment overlap cannot be used with this frame.,'...
' It does not have FIR windows.'],upper(mfilename));
end
switch(F.type)
case {'fwt'}
Fo = frameaccel(F,Lb);
Fo.a = F.g.a(:);
case {'dgt','dgtreal'}
Fo = frameaccel(F,Lb+winLen-1+F.a);
% case {'filterbank','filterbankreal','ufilterbank','ufilterbankreal'}
% lcma = filterbanklength(1,F.a(:,1));
% Fo = frameaccel(F,Lb+winLen-1+lcma);
% assert(all(Fo.a(:,2)==1), '%s: Fractional subsampling is not supported',upper(mfilename) );
% Fo.lcma = lcma;
case {'dwilt'}
Fo = frameaccel(F,Lb+winLen-1+2*F.M);
Fo.a = 2*Fo.M;
case {'wmdct'}
Fo = frameaccel(F,Lb+winLen-1+F.M);
Fo.a = Fo.M;
otherwise
error('%s: Unsupported frame for segola.',upper(mfilename));
end
% This is important otherwise we would get 0 coefficients for some
% blocks.
assert(max(Fo.a(:,1)) <= Lb ,sprintf(['%s: Time step %i is bigger than the',...
' block length %i.'],upper(mfilename),max(Fo.a(:,1)),Lb));
Fo.winLen = winLen;
elseif flags.do_naive
Fo = frameaccel(F,Lb);
end
Fo.blockalg = flags.blockalg;
function winLen = framefirlen(F)
%FRAMEFIRLEN Frame window/filter length
%
% Function returns length of the longest FIR window/filter. The function
% returns -1 if the frame does not have FIR windows.
winLen = -1;
info = [];
switch(F.type)
case {'dgt','dgtreal'}
[~, info] = gabwin(F.g,F.a,F.M,[],F.kv.lt);
case {'dwilt','wmdct'}
[~, info] = wilwin(F.g,F.M,[],upper(mfilename));
case {'filterbank','ufilterbank'}
[~, ~,info] = filterbankwin(F.g,F.a);
case {'filterbankreal','ufilterbankreal'}
[~, ~,info] = filterbankwin(F.g,F.a,'real');
case 'fwt'
winLen = (F.g.a(1)^F.J-1)/(F.g.a(1)-1)*(numel(F.g.g{1}.h)-1)+1;
end;
if ~isempty(info) && isfield(info,'isfir') && info.isfir
if isfield(info,'longestfilter')
winLen = info.longestfilter;
else
winLen = max(info.gl);
end
end