rmeddis@38: function [f,t]=enframe(x,win,inc)
rmeddis@38: %ENFRAME split signal up into (overlapping) frames: one per row. [F,T]=(X,WIN,INC)
rmeddis@38: %
rmeddis@38: %	F = ENFRAME(X,LEN) splits the vector X(:) up into
rmeddis@38: %	frames. Each frame is of length LEN and occupies
rmeddis@38: %	one row of the output matrix. The last few frames of X
rmeddis@38: %	will be ignored if its length is not divisible by LEN.
rmeddis@38: %	It is an error if X is shorter than LEN.
rmeddis@38: %
rmeddis@38: %	F = ENFRAME(X,LEN,INC) has frames beginning at increments of INC
rmeddis@38: %	The centre of frame I is X((I-1)*INC+(LEN+1)/2) for I=1,2,...
rmeddis@38: %	The number of frames is fix((length(X)-LEN+INC)/INC)
rmeddis@38: %
rmeddis@38: %	F = ENFRAME(X,WINDOW) or ENFRAME(X,WINDOW,INC) multiplies
rmeddis@38: %	each frame by WINDOW(:)
rmeddis@38: %
rmeddis@38: %   The second output argument, T, gives the time in samples at the centre
rmeddis@38: %   of each frame. T=i corresponds to the time of sample X(i). 
rmeddis@38: %
rmeddis@38: % Example of frame-based processing:
rmeddis@38: %          INC=20       													% set frame increment
rmeddis@38: %          NW=INC*2     													% oversample by a factor of 2 (4 is also often used)
rmeddis@38: %          S=cos((0:NW*7)*6*pi/NW);								% example input signal
rmeddis@38: %          W=sqrt(hamming(NW+1)); W(end)=[];      % sqrt hamming window of period NW
rmeddis@38: %          F=enframe(S,W,INC);               			% split into frames
rmeddis@38: %          ... process frames ...
rmeddis@38: %          X=overlapadd(F,W,INC);           			% reconstitute the time waveform (omit "X=" to plot waveform)
rmeddis@38: 
rmeddis@38: %	   Copyright (C) Mike Brookes 1997
rmeddis@38: %      Version: $Id: enframe.m,v 1.7 2009/11/01 21:08:21 dmb Exp $
rmeddis@38: %
rmeddis@38: %   VOICEBOX is a MATLAB toolbox for speech processing.
rmeddis@38: %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
rmeddis@38: %
rmeddis@38: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
rmeddis@38: %   This program is free software; you can redistribute it and/or modify
rmeddis@38: %   it under the terms of the GNU General Public License as published by
rmeddis@38: %   the Free Software Foundation; either version 2 of the License, or
rmeddis@38: %   (at your option) any later version.
rmeddis@38: %
rmeddis@38: %   This program is distributed in the hope that it will be useful,
rmeddis@38: %   but WITHOUT ANY WARRANTY; without even the implied warranty of
rmeddis@38: %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
rmeddis@38: %   GNU General Public License for more details.
rmeddis@38: %
rmeddis@38: %   You can obtain a copy of the GNU General Public License from
rmeddis@38: %   http://www.gnu.org/copyleft/gpl.html or by writing to
rmeddis@38: %   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
rmeddis@38: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
rmeddis@38: 
rmeddis@38: nx=length(x(:));
rmeddis@38: nwin=length(win);
rmeddis@38: if (nwin == 1)
rmeddis@38:    len = win;
rmeddis@38: else
rmeddis@38:    len = nwin;
rmeddis@38: end
rmeddis@38: if (nargin < 3)
rmeddis@38:    inc = len;
rmeddis@38: end
rmeddis@38: nf = fix((nx-len+inc)/inc);
rmeddis@38: f=zeros(nf,len);
rmeddis@38: indf= inc*(0:(nf-1)).';
rmeddis@38: inds = (1:len);
rmeddis@38: f(:) = x(indf(:,ones(1,len))+inds(ones(nf,1),:));
rmeddis@38: if (nwin > 1)
rmeddis@38:     w = win(:)';
rmeddis@38:     f = f .* w(ones(nf,1),:);
rmeddis@38: end
rmeddis@38: if nargout>1
rmeddis@38:     t=(1+len)/2+indf;
rmeddis@38: end
rmeddis@38: 
rmeddis@38: