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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) ???? - INRIA - Scilab
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt
function []=auwrite(y,Fs,nbits,method,aufile)
//Write .au sound file.
//auwrite(y,aufile) writes a sound file specified by the
//string aufile. The data should be arranged with one channel
//per column. Amplitude values outside the range [-1,+1] are
//clipped prior to writing.
//
//Supports multi-channel data for 8-bit mu-law, and 8- and
//16-bit linear formats:
//
//auwrite(y,Fs,aufile) specifies the sample rate of the data
//in Hertz.
//
//auwrite(y,Fs,bits,aufile) selects the number of bits in
//the encoder. Allowable settings are bits=8 and bits=16.
//
//auwrite(y,Fs,bits,method,aufile) allows selection of the
//encoding method, which can be either 'mu' or 'linear'.
//Note that mu-law files must be 8-bit. By default, method='mu'.
// test :
// auwrite(y,44100,8,'mu','poo.au')
// aplay -c 1 -f MU_LAW --rate=22050 poo.au
//
// Get default:
[nargout,nargin] = argn(0)
Fs_pref = 22050;
nbits_pref = 8;
method_pref = "mu";
if nargin==1 then
error(msprintf(gettext("%s: Wrong number of input arguments: %d to %d expected.\n"),"auwrite",2,5));
elseif nargin>5 then
error(msprintf(gettext("%s: Wrong number of input arguments: %d to %d expected.\n"),"auwrite",2,5));
elseif nargin==4 then
aufile = method;
method = method_pref;
elseif nargin==3 then
aufile = nbits;
method = method_pref;
nbits = nbits_pref;
elseif nargin==2 then
aufile = Fs;
method = method_pref;
nbits = nbits_pref;
Fs = Fs_pref;
end
if ~(type(aufile)==10) then
error(msprintf(gettext("%s: Wrong values for input argument: Filename must be a string.\n"),"auwrite"));
end
if strindex(aufile,".")==[] then
aufile = aufile+".au";
end
[fid,junk] = mopen(aufile,"wb",0) // Big-endian
if junk<0 then
error(msprintf(gettext("%s: Cannot open file %s.\n"),"auwrite",aufile));
end
if length(size(y)) > 2 then
error(msprintf(gettext("%s: An error occurred: %s\n"),"auwrite",gettext("Data array must have 1- or 2-dimensions only.")));
end
if size(y,2)==1 then
y = y';
end
// Clip data to normalized range [-1,+1]:
i = matrix(find(abs(y)>1),1,-1);
if ~(i==[]) then
y(i) = sign(y(i));
warning(gettext("Data clipped during write to file."));
end
snd = write_sndhdr(fid,Fs,nbits,method,size(y));
if write_sndata(fid,snd,y) then
error(msprintf(gettext("%s: An error occurred: %s\n"),"auwrite",gettext("Error while writing sound file.")));
end
mclose(fid);
endfunction
function [status]=write_sndata(fid,snd,data)
status = 0;
if snd("format")==1 then
dtype = "uc";
data = lin2mu(data);
elseif snd("format")==2 then
dtype = "c";// 'int8';
data = round(data*(2^7-1));
elseif snd("format")==3 then
dtype = "sb";// 'int16"
data = round(data*(2^15-1));
elseif snd("format")==5 then
dtype = "ib";// 'int32"
data = round(data*(2^31-1));
elseif snd("format")==6 then
dtype = "fb";
//
elseif snd("format")==7 then
dtype = "db";// double precision
//
else
status = -1;
return
end
total_samples = snd("samples")*snd("chans");
mput(data,dtype,fid);
endfunction
function [snd]=write_sndhdr(fid,Fs,nbits,method,sz)
// write header part
if method=="mu" then
if nbits~=8 then
error(msprintf(gettext("%s: An error occurred: %s\n"),"auwrite",gettext("Mu-law can only be used with 8 bit data. Use method=''linear'' instead.")));
end
snd.format = 1;
snd.bits = 8;
elseif method=="linear" then
if nbits==8 then
snd.format=2 // 8-bit linear
snd.bits=8
elseif nbits==16 then
snd.format=3 // 16-bit linear
snd.bits=16
elseif nbits==32 then
snd.format=5 // 32-bit linear
snd.bits=32;
elseif nbits==64 then
snd.format=7; // Double-precision
snd.bits=64;
else
error(msprintf(gettext("%s: An error occurred: %s\n"),"auwrite",gettext("Unrecognized data format.")));
return
end
else
error(msprintf(gettext("%s: An error occurred: %s\n"),"auwrite",gettext("Unrecognized data format.")));
end
// Define sound header structure:
snd("samples")=sz(2)
snd("chans")=sz(1)
total_samples = snd("samples")*snd("chans");
bytes_per_sample = ceil(snd("bits")/8);
snd("rate")=Fs
snd("databytes")=bytes_per_sample*total_samples
snd("offset")=28
snd("info")="SCI0";
mput(ascii(".snd"),"c",fid); // magic number
mput(snd("offset"),"uib",fid); // data location
mput(snd("databytes"),"uib",fid); // size in bytes
mput(snd("format"),"uib",fid); // data format
//
mput(snd("rate")/snd("chans"),"uib",fid); // sample rate
mput(snd("chans"),"uib",fid); // channels
mput(ascii(snd("info")),"c",fid); // info
endfunction
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