enframe

ENFRAME split signal up into (overlapping) frames: one per row. [F,T]=(X,WIN,INC)

    F = ENFRAME(X,LEN) splits the vector X(:) up into
    frames. Each frame is of length LEN and occupies
    one row of the output matrix. The last few frames of X
    will be ignored if its length is not divisible by LEN.
    It is an error if X is shorter than LEN.

    F = ENFRAME(X,LEN,INC) has frames beginning at increments of INC
    The centre of frame I is X((I-1)*INC+(LEN+1)/2) for I=1,2,...
    The number of frames is fix((length(X)-LEN+INC)/INC)

    F = ENFRAME(X,WINDOW) or ENFRAME(X,WINDOW,INC) multiplies
    each frame by WINDOW(:)

   The second output argument, T, gives the time in samples at the centre
   of each frame. T=i corresponds to the time of sample X(i). 

 Example of frame-based processing:
          INC=20                                                           % set frame increment
          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+1)); W(end)=[];      % 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)

0001 function [f,t]=enframe(x,win,inc)
0002 %ENFRAME split signal up into (overlapping) frames: one per row. [F,T]=(X,WIN,INC)
0003 %
0004 %    F = ENFRAME(X,LEN) splits the vector X(:) up into
0005 %    frames. Each frame is of length LEN and occupies
0006 %    one row of the output matrix. The last few frames of X
0007 %    will be ignored if its length is not divisible by LEN.
0008 %    It is an error if X is shorter than LEN.
0009 %
0010 %    F = ENFRAME(X,LEN,INC) has frames beginning at increments of INC
0011 %    The centre of frame I is X((I-1)*INC+(LEN+1)/2) for I=1,2,...
0012 %    The number of frames is fix((length(X)-LEN+INC)/INC)
0013 %
0014 %    F = ENFRAME(X,WINDOW) or ENFRAME(X,WINDOW,INC) multiplies
0015 %    each frame by WINDOW(:)
0016 %
0017 %   The second output argument, T, gives the time in samples at the centre
0018 %   of each frame. T=i corresponds to the time of sample X(i).
0019 %
0020 % Example of frame-based processing:
0021 %          INC=20                                                           % set frame increment
0022 %          NW=INC*2                                                         % oversample by a factor of 2 (4 is also often used)
0023 %          S=cos((0:NW*7)*6*pi/NW);                                % example input signal
0024 %          W=sqrt(hamming(NW+1)); W(end)=[];      % sqrt hamming window of period NW
0025 %          F=enframe(S,W,INC);                           % split into frames
0026 %          ... process frames ...
0027 %          X=overlapadd(F,W,INC);                       % reconstitute the time waveform (omit "X=" to plot waveform)
0028 
0029 %       Copyright (C) Mike Brookes 1997
0030 %      Version: $Id: enframe.m 713 2011-10-16 14:45:43Z dmb $
0031 %
0032 %   VOICEBOX is a MATLAB toolbox for speech processing.
0033 %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
0034 %
0035 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0036 %   This program is free software; you can redistribute it and/or modify
0037 %   it under the terms of the GNU General Public License as published by
0038 %   the Free Software Foundation; either version 2 of the License, or
0039 %   (at your option) any later version.
0040 %
0041 %   This program is distributed in the hope that it will be useful,
0042 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
0043 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0044 %   GNU General Public License for more details.
0045 %
0046 %   You can obtain a copy of the GNU General Public License from
0047 %   http://www.gnu.org/copyleft/gpl.html or by writing to
0048 %   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
0049 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0050 
0051 nx=length(x(:));
0052 nwin=length(win);
0053 if (nwin == 1)
0054    len = win;
0055 else
0056    len = nwin;
0057 end
0058 if (nargin < 3)
0059    inc = len;
0060 end
0061 nf = fix((nx-len+inc)/inc);
0062 f=zeros(nf,len);
0063 indf= inc*(0:(nf-1)).';
0064 inds = (1:len);
0065 f(:) = x(indf(:,ones(1,len))+inds(ones(nf,1),:));
0066 if (nwin > 1)
0067     w = win(:)';
0068     f = f .* w(ones(nf,1),:);
0069 end
0070 if nargout>1
0071     t=(1+len)/2+indf;
0072 end
0073 
0074