intanaly.m

FS1016源代码

% 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.
%
% ******************************************************************
% INTANALY
%
% PORTED TO MATLAB FROM CELP 3.2a C RELEASE
% 6-20-94
%
% ******************************************************************
%
% DESCRIPTION
%
% Linearly interpolate between transmitted LSPs to generate 4
% intermediate sets of LSP frequencies for subframe analysis.
%
% DESIGN NOTES
%
% Linearly interpolates lsp's for analysis in
% nn (=4) subframes.  This is a combination of inter- and
% intra-frame interpolation.  There are two routines, one for the
% analyzer and one for the synthesizer.
%
% The lsps are interpolated from two transmitted frames,
% old and new.  The lsp interpolation is calculated as follows:
%
%       superframe: old               new
%
%   |                 |                     |
%   |---------------------|---------------------|
%   |                 |                     |
%   \                                       /
%    \                                    /
%
%       subframe:
%             1       2        3        4
%         |                          |
%       ...---|--------|--------|--------|--------|
%         |                              |
%                         v       v        v        v
%
%       weighting:
%               old:     7/8      5/8      3/8      1/8
%               new:     1/8      3/8      5/8      7/8
%
%       Note: This is dependent on nn = ll/l = 4
%
% VARIABLES
%
% INPUTS
%   nn         -     Number of subframes per frame
%   lspnew     -     New frequency array (LSPs)
%                    (= new portion of LSP superframe)
%   no         -     LPC filter order
%
% OUTPUTS
%   lsp        -     Interpolated frequency matrix
%
% INTERNALS
%   tempfreq   -     Monotonicity correction swap value
%   i,j        -     Counter indicies
%
% GLOBALS
%   w          -     Interpolation weights
%   lspold     -     Old frame portion of LSP superframe
%   oldlsp     -     Last subframe of previous frame LSPs
%                    for ill-conditioned cases
%   FrameCnt   -     Current frame number
%
% ******************************************************************

function lsp = intanaly( lspnew, nn, no )

% DECLARE GLOBAL/STATIC VARIABLES
global w lspold oldlsp

% INTERPOLATE LSPs AND TEST FOR MONOTONICITY
for i = 1:nn
    lsp( i, 1:no ) = ( ( w(1,i) * lspold( 1:no ) ) + ( w(2,i) * lspnew( 1:no ) ) )';

    % CHECK FOR MONOTONICALLY INCREASING LSPs AND SWAP CROSSED LSPs
    if any( lsp(i,2:no) < lsp(i,1:no-1) )
	for j = 2:no
	    if lsp(i,j) < lsp(i,j-1)
		fprintf( 'test.out', 'intanaly: Swapping nonmono lsps\n' );
		tempfreq = lsp(i,j);
		lsp(i,j) = lsp(i,j-1)
		lsp(i,j-1) = tempfreq;
	    end
	end
    end

    % RECHECK FOR MONOTONICALLY INCREASING LSPs AND SUBSTITUTE
    % OLD LSPs IF STILL NONMONOTONIC
    if any( lsp(i,2:no) < lsp(i,1:no-1) )
	fprintf( 'test.out', 'intanaly: Resetting interp LSPs at frame %d\n', FrameCnt );
	if i == 0
	    lsp( 1, 1:no ) = oldlsp( 1:no );
	else
	    lsp( i, 1:no ) = lsp( i-1, 1:no );
	end
    end
end

% SAVE LSPs FOR NEXT PASS
lspold( 1:no ) = lspnew( 1:no );
oldlsp( 1:no ) = lsp( nn, 1:no );