celpanal.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.
%
% ******************************************************************
% CELPANAL
%
% NSA CELP 3.2a ANALYSIS DRIVER
%
% PORTED TO MATLAB FROM CELP 3.2a C RELEASE
% 8-2-94
%
% ******************************************************************
%
% DESCRIPTION
%
% CELP 3.2a analysis driver
%
% DESIGN NOTES
%
% This driver has been derived from the main loop of the NSA CELP 3.2a
% simulation.  CELP analysis accepts a PCM binary speech file as input, then
% produces a hex bitstream (144 bits/frame) and hex file as simulation
% output.  Bitstream output is decoded and used for synthesis by CELPSYN.M.
%
% VARIABLES
%
% INTERNALS
%
%   NOTE:  Many of these variables are initialized in init.m
%
%   iarf          -    Unprocessed input speech data
%   snew          -    Input speech buffer (1 frame ahead)
%   sold          -    Input speech buffer (1 frame behind)
%   ssub          -    Subframe analysis buffer (ll samples = 1/2 old, 1/2 new)
%   scale         -    Input speech scale factor
%   minv          -    Minimum allowed input speech sample value
%   maxv          -    Maximum allowed input speech sample value
%   ahpf          -    H(Z) denominator, input speech highpass filter
%   bhpf          -    H(Z) numerator, input speech highpass filter
%   dhpf1         -    Filter memory, input highpass filter
%   hamw          -    Hamming window, one full frame in length
%   ll            -    Frame length, in samples
%   l             -    Subframe length, in samples
%   no            -    LPC filter order
%   fcn           -    LPC predictor coefficients {1/A(Z) coefficients}, synthesis filter
%   rcn           -    Synthesis filter reflection coefficients
%   lspflag       -    LSP error flag
%   newfreq       -    LSP frequencies derived from LPC direct form coefficients (quantized)
%   findex        -    LSP quantization table indicies
%   sbits         -    Bit allocation, LSP quantization
%   pbits         -    Bit allocation, pitch lag quantization
%   unqfreq       -    Unquantized version of LSP frequencies
%   dm2           -    Spectral distortion measures, current frame
%   sumdm2        -    Average spectral distortion measures, summation
%   framedm2      -    Average spectral distortion measures, framecount
%   stream        -    CELP analysis output bitstream
%   pointer       -    CELP analysis output bitstream current pointer
%   lsp           -    Linearly interpolated lsps for each subframe of current frame
%   nn            -    Number of subframes
%   subframe      -    Current subframe under analysis
%   fci           -    Direct form LPC coefficients, obtained from interpolated, quantized LSPs
%   fc            -    Copy of fci
%   nseg          -    Cumulative subframe counter
%   sfl, sfh      -    Subframe boundaries within current frame buffer
%   v             -    Optimum synthesis filter excitation derived from codebook searches
%   lp            -    Pitch analysis subframe length, in samples
%   tauptr        -    Pitch delay pointer
%   minptr        -    Minimum delay pointer
%   pdencode      -    Pitch delay (tau) encoding table
%   pindex        -    Pitch gain index into pitch gain table
%   cbindex       -    Stochastic codebook index
%   cbbits        -    Bit allocation, stochastic codebook index
%   gindex        -    Stochastic codebook gain index (into gain table)
%   cbgbits       -    Bit allocation, stochastic codebook gain
%   protect       -    Hamming bit protection enable/disable flag
%   bitprotect    -    Bitstream indicies of bits protected by the hamming code
%   codeword      -    Hamming (15,11) codeword, formed from protected bits
%   paritybit     -    Extraneous paritybit used for codeword parity overall
%   hmatrix       -    Hamming matrix, used during hamming codeword generation
%   sync          -    Sync bit, CELP analysis output bitstream
%   savestream    -    Copy of CELP analysis output bitstream
%   bitperm       -    Bit stream permutation table
%   pstream       -    Permuted version of CELP analysis output bitstream
%   line          -    One frame of hex bitstream CELP analysis output,
%                      used to generate hex file 'ofile.cha'
%
% GLOBALS
%   FrameCnt      -    Current frame number
%   SubFrameCnt   -    Current subframe number
%   guiFDM2       -    Spectral distortion averaging frame count
%   guisdm2       -    Spectral distortion summation over FDM2 frames
%   guidm2        -    Spectral distortion measures, current frame
%   guiState      -    Graphical output or status output mode
%                      0 = status mode (non-interactive), 1 = graphics mode
%
% CONSTANTS
%   OMEGA         -    Expansion coefficient for LPC filter pole bandwidth
%   CODELENGTH1   -    Hamming codeword overall length (in bits)
%   CODELENGTH2   -    Hamming codeword data length (in bits)
%
% ******************************************************************

% DECLARE GLOBAL VARIABLES
global FrameCnt guiState SubFrameCnt guiFDM2 guisdm2 guidm2

% SCALE AND CLAMP INPUT DATA TO 16-BIT INTEGER RANGE
snew = min( [ (iarf .* scale)'; maxv ] )';
snew = max( [ snew'; minv ] )';

% RUN HIGHPASS FILTER TO ELIMINATE HUM AND LF NOISE
[ snew, dhpf1 ] = filter( bhpf, ahpf, snew, dhpf1 );

% MAINTAIN SSUB SUBFRAME ANALYSIS BUFFER.  IT IS
% 1/2 FRAME BEHIND SNEW AND 1/2 FRAME AHEAD OF SOLD.
ssub( 1:ll/2 ) = sold( (ll/2)+1:ll );
ssub( (ll/2)+1:ll ) = snew( 1:ll/2 );

% UPDATE SOLD WITH CONTENTS OF SNEW
sold = snew;

% DO LPC SPECTRAL ANALYSIS (OPEN LOOP)
[ fcn, rcn ] = autohf( snew, hamw, ll, no, OMEGA );

% GENERATE LSP FREQUENCIES FROM PREDICTOR COEFFICIENTS
[ newfreq, lspflag ] = pctolsp2( fcn, no );

% ALERT USER TO LSP ERROR CONDITIONS
if lspflag == TRUE
    fprintf( 'celp: Bad "new" lsp at frame: %d\n', FrameCnt );
end

% SAVE UNQUANTIZED LSP
unqfreq = newfreq;

% QUANTIZE LSPs
[ newfreq, findex ] = lsp34( newfreq, no, sbits );

% MEASURE SPECTRAL DISTORTION DUE TO LSP QUANTIZATION
[ dm2, sumdm2, framedm2 ] = specdist( unqfreq, newfreq, no, sumdm2, framedm2 );
guidm2 = dm2;  guisdm2 = sumdm2; guiFDM2 = framedm2;

% PACK LSP QUANTIZATION VALUES INTO BIT STREAM
[ stream, pointer ] = cpack( findex, sbits, pointer, stream );

% LINEARLY INTERPOLATE FRAME LSPs FOR EACH SUBFRAME
lsp = intanaly( newfreq, nn, no );

% SEARCH ADAPTIVE AND STOCHASTIC CODEBOOKS FOR EACH SUBFRAME
for subframe = 1:nn

    % OBTAIN SHORT TERM PREDICTOR COEFFICIENTS FROM QUANTIZED LSPs
    fci = lsptopc( lsp(subframe,:)', no );
    fc = fci;
    nseg = nseg + 1;

    % SEARCH ADAPTIVE AND STOCHASTIC CODEBOOKS
    sfl = ((subframe-1)*l)+1; sfh = sfl+l-1;
    v(sfl:sfh) = csub( ssub(sfl:sfh), l, lp );

    % PACK PARAMETER INDICIES INTO BITSTREAM ARRAY
    % PITCH DELAY INDEX
    if rem( subframe, 2 ) ~= 0
        [ stream, pointer ] = ...
        packtau( tauptr-minptr, pbits(1), pdencode, stream, pointer );
    else
        [ stream, pointer ] = ...
        cpack( tauptr-minptr, pbits(2), pointer, stream );
    end

    % PITCH GAIN INDEX
    [ stream, pointer ] = cpack( pindex, pbits(3), pointer, stream );

    % STOCHASTIC CODEWORD INDEX
    [ stream, pointer ] = cpack( cbindex-1, cbbits, pointer, stream );

    % STOCHASTIC GAIN INDEX
    [ stream, pointer ] = cpack( gindex, cbgbits, pointer, stream );
end

% ADD BIT ERROR PROTECTION TO THE ANALYSIS BIT STREAM
if protect == TRUE

    % FIRST, EXTRACT BITS TO PROTECT
    codeword( 1:CODELENGTH2 ) = stream( bitprotect( 1:CODELENGTH2 ) );

    % HAMMING ENCODE THE CODEWORD
    [ paritybit, codeword ] = encodham( CODELENGTH1, CODELENGTH2, hmatrix, codeword );

    % PACK FUTURE BIT
    [ stream, pointer ] = cpack( 0, 1, pointer, stream );

    % PACK PARITY BITS
    [ stream, pointer ] = cpack( codeword( CODELENGTH2+1:CODELENGTH1 ), ...
                                 [1,1,1,1], pointer, stream );

    % TOGGLE AND PACK THE SYNC BIT
    sync = ~sync;
    [ stream, pointer ] = cpack( sync, 1, pointer, stream );
end

% COPY BIT STREAM
savestream = stream;

% REARRANGE ORIGINAL BIT STREAM FOR TRANSMISSION
pstream = stream( bitperm );

% GENERATE HEX FILE, REPRESENTING THE CELP ANALYSIS BIT STREAM
line = puthex( STREAMBITS, pstream );
fprintf( 'ofile.cha', '%s\n', line );