/usr/share/freemat/toolbox/io/wavwrite.m is in freemat-data 4.0-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 | % WAVWRITE WAVWRITE Write a WAV Audio File
%
% Usage
%
% The wavwrite funtion writes an audio signal to a linear PCM WAV
% file. The simplest form for its use is
%
% wavwrite(y,filename)
%
% which writes the data stored in y to a WAV file with the name
% filename. By default, the output data is assumed to be sampled at a
% rate of 8 KHz, and is output using 16 bit integer format. Each column
% of y is written as a separate channel. The data are clipped to the
% range [-1,1] prior to writing them out. If you want the data to be
% written with a different sampling frequency, you can use the following
% form of the wavwrite command:
%
% wavwrite(y,SampleRate,filename)
%
% where SampleRate is in Hz. Finally, you can specify the number of
% bits to use in the output form of the file using the form
%
% wavwrite(y,SampleRate,NBits,filename)
%
% where NBits is the number of bits to use. Legal values include
% 8,16,24,32. For less than 32 bit output format, the data is
% truncated to the range [-1,1], and an integer output format is used
% (type 1 PCM in WAV-speak). For 32 bit output format, the data is
% written in type 3 PCM as floating point data.
% Copyright (c) 2002-2007 Samit Basu
% Licensed under the GPL
function wavwrite(varargin)
SampleRate = 8000;
NBits = 16;
if (nargin == 2)
y = varargin{1};
filename = varargin{2};
elseif (nargin == 3)
y = varargin{1};
SampleRate = varargin{2};
filename = varargin{3};
elseif (nargin == 4)
y = varargin{1};
SampleRate = varargin{2};
NBits = varargin{3};
filename = varargin{4};
else
error('unrecognized form of wavwrite call.');
end
if (~any(NBits == [8 16 24 32]))
error('unsupported number of bits in output.');
end
if (NBits < 32)
y = max(-1,min(1,y));
if (isvector(y))
y = y(:);
end
end
fp = fopen(filename,'w+b','le');
fwrite(fp,uint8('RIFF'));
% Write a placeholder for the filesize
fwrite(fp,uint32(0));
fwrite(fp,uint8('WAVE'));
fwrite(fp,uint8('fmt '));
fwrite(fp, int32(16));
if (NBits == 32)
fwrite(fp, int16(3));
else
fwrite(fp, int16(1));
end
NumChannels = size(y,2);
SampleFrames = size(y,1);
BytesPerSample = NBits/8;
fwrite(fp,int16(NumChannels));
fwrite(fp,int32(SampleRate));
fwrite(fp,int32(SampleRate*NumChannels*BytesPerSample));
fwrite(fp,int16(NumChannels*BytesPerSample));
fwrite(fp,int16(NBits));
fwrite(fp,uint8('data'));
nbytes = NumChannels*SampleFrames*BytesPerSample;
fwrite(fp,uint32(nbytes));
if (NBits == 8)
fwrite(fp,uint8(y'*127+128));
elseif (NBits == 16)
fwrite(fp,int16(y'*2^15));
elseif (NBits == 24)
fwrite_24bits(fp,int32(y'*2^23));
elseif (NBits == 32)
fwrite(fp,float(y'));
end;
p = ftell(fp);
fseek(fp,4,'bof');
fwrite(fp,uint32(p-8));
fclose(fp);
function fwrite_24bits(fp,data)
t = int2bin(data(:),32);
lo = bin2int(t(:,25:32));
med = bin2int(t(:,17:24));
hi = bin2int(t(:,9:16));
s = [lo,med,hi]';
fwrite(fp,uint8(s));
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