www.gusucode.com > 声音的处理有：LPC，FFT，共振峰，频谱源码程序 > siganlandsystemusingMatlab/SSUM/library/aiffread.m

    function [y,Fs,Format]=aiffread(aiffile,start,stop)
%AIFFREAD  Load AIFF  format sound files.
%   Note: The returned samples are in the range [-32768:32767]
%         and NOT scaled in any fashion 
%   [y]=AIFFREAD(aiffile,start,stop) loads a AIFF format file specified 
%       by "aiffile" from  frame no. start (Def=1) up to frame no. stop
%       (Def=length(file)) and returns the sampled data in variable "y". 
%
%   [y,Fs]=AIFFREAD(aiffile,start,stop) loads a AIFF format file specified 
%       by"aiffile" from frame no. start (Def=1) up to frame no. stop
%       (Def=length(file)) and  returns the sampled data in variable "y" 
%       and the sample rate in variable "Fs".
%   
%   [y,Fs,Format]=AIFFREAD(aiffile,start,stop) loads a AIFF format file 
%        specified by "aiffile" from  frame no. start (Def=1) up to  
%        frame no. stop (Def=length(file)) and  returns the sampled 
%        data in variable "y", the sample rate in variable "Fs", and the 
%        AIFF file format information in variable "Format". 
%        The format information is returned as a 2 element
%        vector with the following order:
%
%               Format(1)       Number of channels
%               Format(2)       Bits per sample
%


if nargin<1 | nargin> 3
  error(sprintf('AIFFREAD takes up to three arguments, which are\n\tthe name of the AIFF file (required)\n\tthe first frame to read\n\tthe last frame to read'));
end

notend = 1;
comread = 0;
ssndread = 0;
if nargin==1
  start=1;
  stop=-1;
end

if nargin ==2 
  stop=-1;
end

if( stop> 0 & stop <= start)
 error('aiffread: No samles selected\n');
 return;
end 

fid=fopen(aiffile,'rb','b');
if fid ~= -1 
	% read aiff chunk
	header=fscanf(fid,'%4s',1);
	if  ~strcmp(header, 'FORM')
	  error('No AIFF File!')
	end
	fsize=fread(fid,1,'long');
        
	header=fscanf(fid,'%4s',1);
	if ~strcmp(header, 'AIFF')
	  disp(['FORM =', header])
	  error('No AIFF File!')
	end

	% read format sub-chunk
	while  notend == 1
	  header=fscanf(fid,'%4c',1);
	  len=fread(fid,1,'long');
	  if strcmp(header,'COMM')
	    if comread == 1
               error('Error reading AIFF chunks: 2 COMM-Chunks detected!')
            end
	    comread = 1;
            Format(1)=fread(fid,1,'short');           % Channel
	    disp(sprintf('Channels   : %d',Format(1)))
            if Format(1) > 4
               error('File contains more then 4 channels!')
            end
	    frames = fread(fid,1,'ulong');            % Frames
	    Format(2)=fread(fid,1,'short');            % bits per sample
            disp(sprintf('Bits/Sample: %d', Format(2)))
	    expon=fread(fid,1,'short');
	    tt   = fread (fid,8,'unsigned char');

	    himant=((((tt(1)*256+tt(2))*256)+tt(3))*256+tt(4));
	    himant=(((((himant *256 +tt(5))*256+tt(6))*256)+tt(7))*256+tt(8))/2^63;
	    if( expon == 0  & himant == 0)
	      Fs = 0;
	    else
	      Fs=(himant) * 2^ (abs(expon) -16383);
	    end
            disp(sprintf('Rate       : %.0f', Fs))
	  elseif strcmp(header, 'SSND')
	    if ssndread == 1
               error('Error reading AIFF chunks: 2 SSND-Chunks detected!')
            end
	    ssndread = 1;
	  
	    offset=fread(fid,1,'ulong');
            dummy=fread(fid,1,'ulong');
	    if dummy ~= 0 
	      disp('AIFF-SSND Chunk specify non zero blocksize ??')
            end
	    fseek(fid,offset,0);


	    if     Format(2) == 8
	       formstr = 'schar';
	    elseif Format(2) == 16
	       formstr = 'short';
        elseif Format(2) == 24
           formstr = 'long';
	    elseif Format(2) == 32
	       formstr = 'slong';
	    end

	    if start>1
	      yd=fread(fid,Format(1)*(start-1),formstr);
	    end	      
            if stop >start & stop < frames
	      frames =stop;
	    end	      
	    yd=fread(fid,Format(1)*(frames-start+1),formstr);
            notend = 0;
          else
	    disp(sprintf(' Skip over %s',header));
	    fseek(fid,len,0);
          end
       end
       fclose(fid);

       if      Format(1) == 1
	y = yd;
       elseif  Format(1) == 2
	ss=size(yd);
    whos
	y = [yd(1:2:ss) yd(2:2:ss)];
       elseif  Format(1) == 3
	ss=size(yd);

	y = [yd(1:3:ss) yd(2:3:ss) yd(3:3:ss)];
       elseif  Format(1) == 4
	ss=size(yd);

	y = [yd(1:4:ss) yd(2:4:ss) yd(3:4:ss) yd(4:4:ss)];
       end
end     


if fid == -1
	error(['Can''t open AIFF file >',aiffile,'< for input!']);
end;