Home > voicebox > lin2pcmu.m

lin2pcmu

PURPOSE ^

LIN2PCMU Convert linear to Mu-law PCM P=(X,S)

SYNOPSIS ^

function p=lin2pcmu(x,s)

DESCRIPTION ^

LIN2PCMU Convert linear to Mu-law PCM P=(X,S)
    pcmu = lin2pcmu(lin) where lin contains a vector
    or matrix of signal values within a range determined by
    the scale factor s (see table below).
    Values outside this range will be clipped.
    The input values will be converted to integer
    Mu-law pcm vlues in the range 0 to 255.
    
    Input values are multiplied by the scale factor s:

           s        Input Range

           1        +-8159
        4004.189931    +-2.03761563 (default)
        8159        +-1

    The default input scaling factor 4004.189931 is equal to
    sqrt((2207^2 + 5215^2)/2) and follows ITU standard G.711.
    The sine wave with PCM-Mu values [158 139 139 158 30 11 11 30]
    has a mean square value of unity corresponding to 0 dBm0.

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function p=lin2pcmu(x,s)
0002 %LIN2PCMU Convert linear to Mu-law PCM P=(X,S)
0003 %    pcmu = lin2pcmu(lin) where lin contains a vector
0004 %    or matrix of signal values within a range determined by
0005 %    the scale factor s (see table below).
0006 %    Values outside this range will be clipped.
0007 %    The input values will be converted to integer
0008 %    Mu-law pcm vlues in the range 0 to 255.
0009 %
0010 %    Input values are multiplied by the scale factor s:
0011 %
0012 %           s        Input Range
0013 %
0014 %           1        +-8159
0015 %        4004.189931    +-2.03761563 (default)
0016 %        8159        +-1
0017 %
0018 %    The default input scaling factor 4004.189931 is equal to
0019 %    sqrt((2207^2 + 5215^2)/2) and follows ITU standard G.711.
0020 %    The sine wave with PCM-Mu values [158 139 139 158 30 11 11 30]
0021 %    has a mean square value of unity corresponding to 0 dBm0.
0022 
0023 
0024 
0025 %      Copyright (C) Mike Brookes 1998
0026 %      Version: $Id: lin2pcmu.m 713 2011-10-16 14:45:43Z dmb $
0027 %
0028 %   VOICEBOX is a MATLAB toolbox for speech processing.
0029 %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
0030 %
0031 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0032 %   This program is free software; you can redistribute it and/or modify
0033 %   it under the terms of the GNU General Public License as published by
0034 %   the Free Software Foundation; either version 2 of the License, or
0035 %   (at your option) any later version.
0036 %
0037 %   This program is distributed in the hope that it will be useful,
0038 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
0039 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0040 %   GNU General Public License for more details.
0041 %
0042 %   You can obtain a copy of the GNU General Public License from
0043 %   http://www.gnu.org/copyleft/gpl.html or by writing to
0044 %   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
0045 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0046 
0047 if nargin < 2 s=4004.189931; end
0048 y=x*s;
0049 y=(abs(y+8031)-abs(y-8031))/2;
0050 q=floor((y+8032)/8032);
0051 [m,e]=log2(abs(y)+33);
0052 p=175+128*q-8*(e+abs(e-6))-floor(32*m-16);

Generated on Tue 19-Sep-2017 12:07:31 by m2html © 2003