disto.m

实现fs1016w的CELP的低速率语音编解码功能的基于vc开发环境的原代码。

% MATLAB SIMULATION OF NSA FS-1016 CELP v3.2
% COPYRIGHT (C) 1995-99 ANDREAS SPANIAS AND TED PAINTER
%
% This Copyright applies only to this particular MATLAB implementation
% of the FS-1016 CELP coder.  The MATLAB software is intended only for educational
% purposes.  No other use is intended or authorized.  This is not a public
% domain program and distribution to individuals or networks is strictly
% prohibited.  Be aware that use of the standard in any form is goverened
% by rules of the US DoD.  Therefore patents and royalties may apply to
% authors, companies, or committees associated with this standard, FS-1016.  For
% questions regarding the MATLAB implementation please contact Andreas
% Spanias at [phone].  For questions on rules,
% royalties, or patents associated with the standard, please contact the DoD.
%
% ALL DERIVATIVE WORKS MUST INCLUDE THIS COPYRIGHT NOTICE.
%
% ******************************************************************
% DISTO
%
% PORTED TO MATLAB FROM CELP 3.2a C RELEASE
% 8-8-94
%
% ******************************************************************
%
% DESCRIPTION
%
% Compute distortion/distance measures and likelihood ratio
%
% DESIGN NOTES
%
% Calculate distortions/distances (log spectral error, etc.).
% See the first reference below for a complete description.  A
% "reference" system is compared against a "test" system.  Because
% of the nonsymetric nature of the Itakura-Saito measure which some
% of these distortion measures are based, poorer measures will be
% obtained if the "reference" and "test" systems are reversed.
% Because of gain uncertainties, a few measures are reported.
% (Peter Kroon generally uses the measure DM(5).)
%
% REFERENCES
%
% 1. "Distance Measures for Speech Processing", A.H. Gray and J.D. Markel,
%    IEEE Trans. on ASSP, Vol. ASSP-24, no. 5, Oct. 1976
%
% 2. "Quantization and Bit Allocation in Speech Processing",
%    A.H. Gray and J.D. Markel,IEEE Trans. on ASSP, Vol. ASSP-24
%    no. 6, Dec. 1976
%
% 3. "A Note on Quantization and Bit Allocation in Speech Processing",
%    A.H. Gray and J.D. Markel,IEEE Trans. on ASSP, Vol. ASSP-25
%    no. 3, June 1977
%
% VARIABLES
%
% INPUTS
%   s          -     "Reference" speech input
%   ts         -     "Test" speech input
%   ws         -     Hamming window, length l
%   l          -     Length of comparison (record lengths)
%   no         -     Filter order
%   sumdm      -     Distances averaging accumulator (current sum)
%   framedm    -     Distances averaging subframe counter (current count)
%
% OUTPUTS
%   dm         -     Distances array (current subframe)
%   sumdm      -     Distances averaging accumulator (current sum)
%   framedm    -     Distances averaging subframe counter (current count)
%
% INTERNALS
%   ssw        -     Windowed "reference" sequence
%   tsw        -     Windowed "test" sequence
%   c0hp       -     0th autocorrelation lag, reference speech
%   chp        -     Higher-order autocorrelation lags, reference speech
%   c0tsw      -     0th autocorrelation lag, test speech
%   ctsw       -     Higher-order autocorrelation lags, test speech
%
% ******************************************************************

function [ dm, sumdm, framedm ] = disto( s, ts, ws, l, no, sumdm, framedm )

% ALLOCATE AUTOCORRELATION LAG VECTORS
chp = zeros( no+1, 1 );
ctsw = zeros( no+1, 1 );

% APPLY HAMMING WINDOW TO REFERENCE AND TEST SPEECH SEQUENCES
ssw = ws .* s;
tsw = ws .* ts;

% COMPUTE AUTO CORRELATION LAGS FOR BOTH REFERENCE AND TEST SEQUENCES
[ c0hp, chp(2:no+1) ] = cor( ssw, l, no );
[ c0tsw, ctsw(2:no+1) ] = cor( tsw, l, no );

% ASSEMBLE AUTOCORRELATION LAGS INTO SINGLE VECTOR
chp(1) = c0hp;
ctsw(1) = c0tsw;

% COMPUTE DISTANCE AND DISTORTION MEASURES
if ( chp(1) ~= 0.00 ) & ( ctsw(1) ~= 0.00 )
    [ dm, sumdm, framedm ] = dist( no, 4*no, chp, ctsw, sumdm, framedm );
end