www.gusucode.com > 声音的处理有：LPC，FFT，共振峰，频谱源码程序 > siganlandsystemusingMatlab/SSUM/library/readaif.m
function [y,fs,wmode,fidx]=readaif(filename,mode,nmax,nskip)
%READAIF Read a .AIF format sound file [Y,FS,WMODE,FIDX]=(FILENAME,MODE,NMAX,NSKIP)
%
% Input Parameters:
%
% FILENAME gives the name of the file (with optional .AIF extension) or alternatively
% can be the FIDX output from a previous call to READAIF
% MODE specifies the following (*=default):
%
% Scaling: 's' Auto scale to make data peak = +-1
% 'r' Raw unscaled data (integer values)
% 'q' Scaled to make 0dBm0 be unity mean square
% 'p' * Scaled to make +-1 equal full scale
% 'o' Scale to bin centre rather than bin edge (e.g. 127 rather than 127.5 for 8 bit values)
% (can be combined with n+p,r,s modes)
% 'n' Scale to negative peak rather than positive peak (e.g. 128.5 rather than 127.5 for 8 bit values)
% (can be combined with o+p,r,s modes)
% File I/O: 'f' Do not close file on exit
%
% NMAX maximum number of samples to read (or -1 for unlimited [default])
% NSKIP number of samples to skip from start of file
% (or -1 to continue from previous read when FIDX is given instead of FILENAME [default])
%
% Output Parameters:
%
% Y data matrix of dimension (samples,channels)
% FS sample frequency in Hz
% WMODE mode string needed to recreate the data file
% FIDX Information row vector containing the element listed below.
%
% (1) file id
% (2) current position in file
% (3) dataoff byte offset in file to start of data
% (4) nsamp number of samples
% (5) nchan number of channels
% (6) nbyte bytes per data value
% (7) bits number of bits of precision
% (8) code Data format: 1=PCM, 2=ADPCM, 6=A-law, 7=Mu-law (always 1 for AIFF)
% (9) fs sample frequency
% (10) offset
% (11) block size
%
% If no output parameters are specified, header information will be printed.
%
% For stereo data, y(:,1) is the left channel and y(:,2) the right
% future enhancements: (1) handle LIST and CAT files as well
% (2) deal with offset and blocksize properly
% (3) handle other chunk types sensibly
% Copyright (C) Mike Brookes 1998
%
% Last modified Tue Aug 12 16:37:56 2003
%
% VOICEBOX is a MATLAB toolbox for speech processing. Home page is at
% 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
% ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to
% Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
if nargin<1 error('Usage: [y,fs,wmode,fidx]=READAIFF(filename,mode,nmax,nskip)'); end
if nargin<2 mode='p';
else mode = [mode(:).' 'p'];
end
k=find((mode>='p') & (mode<='s'));
mno=all(mode~='o'); % scale to input limits not output limits
sc=mode(k(1));
info=zeros(1,11);
if ischar(filename)
fid=fopen(filename,'rb','b');
if fid == -1
fn=[filename,'.aif'];
fid=fopen(fn,'rb','b');
if fid ~= -1 filename=fn; end
end
if fid == -1 error(sprintf('Can''t open %s for input',filename)); end
info(1)=fid;
else
info=filename;
fid=info(1);
end
if ~info(3)
fseek(fid,0,-1); % read file header
header=fread(fid,4,'uchar');
if header' ~= 'FORM' fclose(fid); error(sprintf('File %s does not begin with a FORM group ID',filename)); end
filen=fread(fid,1,'ulong')-4;
header=fread(fid,4,'uchar');
if header' ~= 'AIFF' fclose(fid); error(sprintf('File %s does not begin with a AIFF type ID',filename)); end
fmt=0;
data=0;
while filen % loop to read all chunks
header=fread(fid,4,'char');
len=fread(fid,1,'ulong');
lenx=len+rem(len,2); % round up to an even number
filen=filen-lenx-8;
%fprintf(1,'%s chunk, %d bytes, %d bytes remaining\n',char(header'),len,filen);
if header' == 'COMM' % ******* found COMM chunk *********
fmt=1;
info(5)=fread(fid,1,'ushort'); %number of channels
info(4)=fread(fid,1,'ulong'); %number of samples
info(7)=fread(fid,1,'ushort'); % bits per sample
info(6)=ceil(info(7)/8); % bytes per sample
info(8)=1;
ieeex=fread(fid,5,'ushort'); % read a 10-byte extended ieee format number
fsign=ieeex(1)>32767;
ieeex(1)=ieeex(1)-32768*fsign;
if ~ieeex info(9)=0;
elseif ieeex(1)==32767 info(9)=nan;
else
info(9)=(1-2*fsign)*sum(pow2(ieeex(2:5)',ieeex(1)-(16398:16:16446)));
end
fseek(fid,lenx-18,0); % skip to end of header
elseif header' == 'SSND' % ******* found DATA chunk *********
info(10)=fread(fid,1,'ulong'); %number of channels
info(11)=fread(fid,1,'ulong'); %number of channels
info(3)=ftell(fid);
data=1;
fseek(fid,lenx-8,0); % skip to end of chunk
else % ******* found unwanted chunk *********
fseek(fid,lenx,0);
end
end
end
fs=info(9);
if ~fmt | ~data fclose(fid); error(sprintf('File %s does not contain COMM and SSND chunks',filename)); end
if nargin<4 nskip=info(2);
elseif nskip<0 nskip=info(2);
end
ksamples=info(4)-nskip;
if nargin>2
if nmax>=0
ksamples=min(nmax,ksamples);
end
elseif ~nargout
ksamples=min(5,ksamples);
end
if ksamples>0
info(2)=nskip+ksamples;
pk=pow2(0.5,8*info(6))*(1+(mno/2-all(mode~='n'))/pow2(0.5,info(7))); % use modes o and n to determine effective peak
fseek(fid,info(3)+info(6)*info(5)*nskip,-1);
nsamples=info(5)*ksamples;
if info(6)<3
if info(6)<2
y=fread(fid,nsamples,'schar');
else
y=fread(fid,nsamples,'short');
end
else
if info(6)<4
y=fread(fid,3*nsamples,'uchar')
y=reshape(y,3,nsamples);
y=[1 256 65536]*y-pow2(fix(pow2(y(3,:),-7)),24);
else
y=fread(fid,nsamples,'long');
end
end
if sc ~= 'r'
if sc=='s' sf=1/max(max(abs(y)),1);
elseif sc=='p' sf=1/pk;
else sf=2.03033976/pk;
end
y=sf*y;
else
y=y*pow2(1,info(7)-8*info(6)); % shift to get the data into the LSB end
end
if info(5)>1 y = reshape(y,info(5),ksamples).'; end
else
y=[];
end
if all(mode~='f') fclose(fid); end
if nargout>2
if ~mno wmode=[wmode 'o']; end
if any(mode=='n') wmode=[wmode 'n']; end
wmode=[sc num2str(info(7))];
fidx=info;
elseif ~nargout
fprintf(1,'\n%d Hz sample rate\n%d channel x %d samples x %d bit = %.3g seconds\n',info([9 5 4]), info(7),info(4)/info(9));
end