function [f,t,w]=enframe(x,win,inc,m)
%ENFRAME split signal up into (overlapping) frames: one per row. [F,T]=(X,WIN,INC)
%
% Usage: (1) f=enframe(x,n) % split into frames of length n
%
% (2) f=enframe(x,hamming(n,'periodic'),n/4) % use a 75% overlapped Hamming window of length n
%
% Inputs: x input signal
% win window or window length in samples
% inc frame increment in samples
% m mode input:
% 'z' zero pad to fill up final frame
% 'r' reflect last few samples for final frame
% 'A' calculate window times as the centre of mass
% 'E' calculate window times as the centre of energy
%
% Outputs: f enframed data - one frame per row
% t fractional time in samples at the centre of each frame
% w window function used
%
% By default, the number of frames will be rounded down to the nearest
% integer and the last few samples of x() will be ignored unless its length
% is lw more than a multiple of inc. If the 'z' or 'r' options are given,
% the number of frame will instead be rounded up and no samples will be ignored.
%
% Example of frame-based processing:
% INC=20 % set frame increment in samples
% NW=INC*2 % oversample by a factor of 2 (4 is also often used)
% S=cos((0:NW*7)*6*pi/NW); % example input signal
% W=sqrt(hamming(NW),'periodic')); % sqrt hamming window of period NW
% F=enframe(S,W,INC); % split into frames
% ... process frames ...
% X=overlapadd(F,W,INC); % reconstitute the time waveform (omit "X=" to plot waveform)
% Bugs/Suggestions:
% (1) Possible additional mode options:
% 'u' modify window for first and last few frames to ensure WOLA
% 'a' normalize window to give a mean of unity after overlaps
% 'e' normalize window to give an energy of unity after overlaps
% 'wm' use Hamming window
% 'wn' use Hanning window
% 'x' include all frames that include any of the x samples
% Copyright (C) Mike Brookes 1997-2012
% Version: $Id: enframe.m 1713 2012-03-30 21:27:46Z dmb $
%
% VOICEBOX is a MATLAB toolbox for speech processing.
% Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 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 2 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 can obtain a copy of the GNU General Public License from
% http://www.gnu.org/copyleft/gpl.html or by writing to
% Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
nx=length(x(:));
if nargin<2 || isempty(win)
win=nx;
end
if nargin<4 || isempty(m)
m='';
end
nwin=length(win);
if nwin == 1
lw = win;
w = ones(1,lw);
else
lw = nwin;
w = win(:)';
end
if (nargin < 3) || isempty(inc)
inc = lw;
end
nli=nx-lw+inc;
nf = fix((nli)/inc);
na=nli-inc*nf;
f=zeros(nf,lw);
indf= inc*(0:(nf-1)).';
inds = (1:lw);
f(:) = x(indf(:,ones(1,lw))+inds(ones(nf,1),:));
if nargin>3 && (any(m=='z') || any(m=='r')) && na>0
if any(m=='r')
ix=1+mod(nx-na:nx-na+lw-1,2*nx);
f(nf+1,:)=x(ix+(ix>nx).*(2*nx+1-2*ix));
else
f(nf+1,1:na)=x(1+nx-na:nx);
end
nf=size(f,1);
end
if (nwin > 1) % if we have a non-unity window
f = f .* w(ones(nf,1),:);
end
if nargout>1
if any(m=='E')
t0=sum((1:lw).*w.^2)/sum(w.^2);
elseif any(m=='E')
t0=sum((1:lw).*w)/sum(w);
else
t0=(1+lw)/2;
end
t=t0+inc*(0:(nf-1)).';
end
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