OVERLAPADD join overlapping frames together X=(F,WIN,INC)
Inputs: F(NR,NW) contains the frames to be added together, one
frame per row.
WIN(NW) contains a window function to multiply each frame.
WIN may be omitted to use a default rectangular window
If processing the input in chunks, WIN should be replaced by
ZI on the second and subsequent calls where ZI is the saved
output state from the previous call.
INC gives the time increment (in samples) between
succesive frames [default = NW].
Outputs: X(N,1) is the output signal. The number of output samples is N=NW+(NR-1)*INC.
ZO Contains the saved state to allow a long signal
to be processed in chunks. In this case X will contain only N=NR*INC
output samples.
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 [x,zo]=overlapadd(f,win,inc) 0002 %OVERLAPADD join overlapping frames together X=(F,WIN,INC) 0003 % 0004 % Inputs: F(NR,NW) contains the frames to be added together, one 0005 % frame per row. 0006 % WIN(NW) contains a window function to multiply each frame. 0007 % WIN may be omitted to use a default rectangular window 0008 % If processing the input in chunks, WIN should be replaced by 0009 % ZI on the second and subsequent calls where ZI is the saved 0010 % output state from the previous call. 0011 % INC gives the time increment (in samples) between 0012 % succesive frames [default = NW]. 0013 % 0014 % Outputs: X(N,1) is the output signal. The number of output samples is N=NW+(NR-1)*INC. 0015 % ZO Contains the saved state to allow a long signal 0016 % to be processed in chunks. In this case X will contain only N=NR*INC 0017 % output samples. 0018 % 0019 % Example of frame-based processing: 0020 % INC=20 % set frame increment 0021 % NW=INC*2 % oversample by a factor of 2 (4 is also often used) 0022 % S=cos((0:NW*7)*6*pi/NW); % example input signal 0023 % W=sqrt(hamming(NW+1)); W(end)=[]; % sqrt hamming window of period NW 0024 % F=enframe(S,W,INC); % split into frames 0025 % ... process frames ... 0026 % X=overlapadd(F,W,INC); % reconstitute the time waveform (omit "X=" to plot waveform) 0027 0028 % Copyright (C) Mike Brookes 2009 0029 % Version: $Id: overlapadd.m 713 2011-10-16 14:45:43Z dmb $ 0030 % 0031 % VOICEBOX is a MATLAB toolbox for speech processing. 0032 % Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 0033 % 0034 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0035 % This program is free software; you can redistribute it and/or modify 0036 % it under the terms of the GNU General Public License as published by 0037 % the Free Software Foundation; either version 2 of the License, or 0038 % (at your option) any later version. 0039 % 0040 % This program is distributed in the hope that it will be useful, 0041 % but WITHOUT ANY WARRANTY; without even the implied warranty of 0042 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 0043 % GNU General Public License for more details. 0044 % 0045 % You can obtain a copy of the GNU General Public License from 0046 % http://www.gnu.org/copyleft/gpl.html or by writing to 0047 % Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. 0048 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0049 [nr,nf]=size(f); % number of frames and frame length 0050 if nargin<2 0051 win=nf; % default increment 0052 end 0053 if isstruct(win) 0054 w=win.w; 0055 if ~numel(w) && length(w)~=nf 0056 error('window length does not match frames size'); 0057 end 0058 inc=win.inc; 0059 xx=win.xx; 0060 else 0061 if nargin<3 0062 inc=nf; 0063 end 0064 if numel(win)==1 && win==fix(win) && nargin<3 % win has been omitted 0065 inc=win; 0066 w=[]; 0067 else 0068 w=win(:).'; 0069 if length(w)~=nf 0070 error('window length does not match frames size'); 0071 end 0072 if all(w==1) 0073 w=[]; 0074 end 0075 end 0076 xx=[]; % partial output from previous call is null 0077 end 0078 nb=ceil(nf/inc); % number of overlap buffers 0079 no=nf+(nr-1)*inc; % buffer length 0080 z=zeros(no,nb); % space for overlapped output speech 0081 if numel(w) 0082 z(repmat(1:nf,nr,1)+repmat((0:nr-1)'*inc+rem((0:nr-1)',nb)*no,1,nf))=f.*repmat(w,nr,1); 0083 else 0084 z(repmat(1:nf,nr,1)+repmat((0:nr-1)'*inc+rem((0:nr-1)',nb)*no,1,nf))=f; 0085 end 0086 x=sum(z,2); 0087 if ~isempty(xx) 0088 x(1:length(xx))=x(1:length(xx))+xx; % add on leftovers from previous call 0089 end 0090 if nargout>1 % check if we want to preserve the state 0091 mo=inc*nr; % completed output samples 0092 if no<mo 0093 x(mo,1)=0; 0094 zo.xx=[]; 0095 else 0096 zo.xx=x(mo+1:end); 0097 zo.w=w; 0098 zo.inc=inc; 0099 x=x(1:mo); 0100 end 0101 elseif ~nargout 0102 if isempty(xx) 0103 k1=nf-inc; % dubious samples at start 0104 else 0105 k1=0; 0106 end 0107 k2=nf-inc; % dubious samples at end 0108 plot(1+(0:nr-1)*inc,x(1+(0:nr-1)*inc),'>r',nf+(0:nr-1)*inc,x(nf+(0:nr-1)*inc),'<r', ... 0109 1:k1+1,x(1:k1+1),':b',k1+1:no-k2,x(k1+1:end-k2),'-b',no-k2:no,x(no-k2:no),':b'); 0110 xlabel('Sample Number'); 0111 title(sprintf('%d frames of %d samples with %.0f%% overlap = %d samples',nr,nf,100*(1-inc/nf),no)); 0112 end