wavread (Re: Help required..)

[Akira Nishimura]

From: Sengupta Sourav <address@hidden>
Subject: Help required..
Date: Sun, 15 Apr 2001 23:50:40 -0700 (PDT)
Message-ID: <address@hidden>

>Sir,
>
>I have a matlab file in which i have used the function
>waveread as in..
>
>[x,fs,bits]=wavread('clip.wav');

It may be not perfect, but simple example.

function [sig, sf, bits]=wavread(wavefile, siz)

% WAVREAD  Load Microsoft Windows .WAV format sound files.
%
%  [sig, sf, bits] = wavread(wavfile [, siz])
%   
%        sig : signal
%         sf : sampling freq.
%       bits : the number of bits per sample
%    wavfile : file name 
%              (The ".wav" extension is appended if no extension is given.)
%        siz : 'size' returns the size of the audio data
%            : [N1 N2] returns only samples N1 through N2

if nargin < 1
  help wavread;
  return;
end

if isempty(findstr(wavefile,'.'))
  wavefile=[wavefile,'.wav'];
end

fid=fopen(wavefile,'r','ieee-le');
if fid == -1
  error('Can''t open .WAV file for input!');
end;

% read riff chunk
header=fread(fid,4,'uchar');
header=fread(fid,1,'ulong');
header=fread(fid,4,'uchar');

% read format sub-chunk
header=fread(fid,4,'uchar');
header=fread(fid,1,'ulong');

format(1)=fread(fid,1,'ushort');                % Format 
format(2)=fread(fid,1,'ushort');                % Channel
format(3)=fread(fid,1,'ulong');                 % Samples per second
header=fread(fid,1,'ulong');
block=fread(fid,1,'ushort');
format(4)=fread(fid,1,'ushort');                % Bits per sample

% read data sub-chunck
header=fread(fid,4,'uchar');
nbyteforsamples=fread(fid,1,'ulong');

nsamples=nbyteforsamples/block;
if(nargin < 2)
  siz = [1 nsamples];
end

sf = format(3);
bits = format(4);
if(strcmp(siz, 'size'))
  sig = [nsamples, format(2)];
  fclose(fid);
  return;
end

st = siz(1);
et = siz(2);

if (format(4)+format(2) == 9)
  fseek(fid, (st-1), 0);
  [sig, cnt] = fread(fid, [1, et-st+1],'uchar');
  sig = (sig-128)/128;
end
if (format(4)+format(2) == 10)
  fseek(fid, (st-1)*2, 0);
  [sig, cnt] = fread(fid, [2,et-st+1], 'uchar');
  sig = (sig-128)/128;
end

if (format(4)+format(2) == 17)
  fseek(fid, (st-1)*2, 0);
  [sig, cnt] = fread(fid, [1, et-st+1], 'short');
  sig = sig/32768;
end

if (format(4)+format(2) == 18)
  fseek(fid, (st-1)*4, 0);
  [sig, cnt] = fread(fid,[2,et-st+1],'short');
  sig = sig/32768;
end
fclose(fid);

sig = sig';

_/_/_/  _/  _/            _/            _/_/        Akira NISHIMURA
 _/    _/  _/            _/             | Dept. of Media and Cultural Studies
_/okyo _/_/niversity of _/nformation _/_/ciences address@hidden
                   http://www.rsch.tuis.ac.jp/~akira



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