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Fixed-point LSP and LPC decoding routines for ACELP-based codecs
Originally committed as revision 12978 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Vladimir Voroshilov
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/*
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* LSP routines for ACELP-based codecs
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*
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* Copyright (c) 2008 Vladimir Voroshilov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <inttypes.h>
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#include "avcodec.h"
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#define FRAC_BITS 14
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#include "mathops.h"
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#include "lsp.h"
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#include "acelp_math.h"
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void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max)
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{
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int i, j;
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/* sort lsfq in ascending order. float bubble agorithm,
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O(n) if data already sorted, O(n^2) - otherwise */
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for(i=0; i<9; i++)
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for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
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FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
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for(i=0;i<10; i++)
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{
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lsfq[i] = FFMAX(lsfq[i], lsfq_min);
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lsfq_min = lsfq[i] + lsfq_min_distance;
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}
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lsfq[9] = FFMIN(lsfq[9], lsfq_max);//Is warning required ?
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}
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void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf)
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{
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int i;
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/* Convert LSF to LSP, lsp=cos(lsf) */
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for(i=0;i<10; i++)
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// 20861 = 2.0 / PI in (0.15)
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lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
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}
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/**
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* \brief decodes polynomial coefficients from LSP
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* \param f [out] decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
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* \param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)
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*/
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static void lsp2poly(int* f, const int16_t* lsp)
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{
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int i, j;
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f[0] = 0x400000; // 1.0 in (3.22)
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f[1] = -lsp[0] << 8; // *2 and (0.15) -> (3.22)
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for(i=2; i<=5; i++)
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{
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f[i] = f[i-2];
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for(j=i; j>1; j--)
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f[j] -= MULL(f[j-1], lsp[2*i-2]) - f[j-2]; // (3.22) * (0.15) * 2 -> (3.22)
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f[1] -= lsp[2*i-2] << 8;
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}
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}
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void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp)
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{
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int i;
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int f1[6]; // (3.22)
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int f2[6]; // (3.22)
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lsp2poly(f1, lsp );
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lsp2poly(f2, lsp+1);
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/* 3.2.6 of G.729, Equations 25 and 26*/
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lp[0] = 4096;
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for(i=1; i<6; i++)
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{
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int ff1 = f1[i] + f1[i-1]; // (3.22)
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int ff2 = f2[i] - f2[i-1]; // (3.22)
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ff1 += 1 << 10; // for rounding
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lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
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lp[11-i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
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}
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}
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void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev)
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{
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int16_t lsp_1st[10]; // (0.15)
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int i;
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/* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
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for(i=0;i<10;i++)
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#ifdef G729_BITEXACT
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lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1);
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#else
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lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
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#endif
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ff_acelp_lsp2lpc(lp_1st, lsp_1st);
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/* LSP values for second subframe (3.2.5 of G.729)*/
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ff_acelp_lsp2lpc(lp_2nd, lsp_2nd);
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}
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@ -0,0 +1,63 @@
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/*
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* LSP computing for ACELP-based codecs
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*
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* Copyright (c) 2008 Vladimir Voroshilov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef FFMPEG_ACELP_LPC_H
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#define FFMPEG_ACELP_LPC_H
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/**
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(I.F) means fixed-point value with F fractional and I integer bits
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*/
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/**
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* \brief keep distance between LSFs.
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* \param lsfq [in/out] LSF to check and adjust
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* \param lsfq_min_distance minimum distance between LSFs
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* \param lsfq_min minimum allowed LSF value
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* \param lsfq_max maximum allowed LSF value
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*/
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void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsqf_min, int lsfq_max);
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/**
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* \brief Convert LSF to LSP
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* \param lsp [out] LSP coefficients (-0x8000 <= (0.15) < 0x8000)
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* \param lsf normalized LSF coefficients (0 <= (2.13) < 0x2000 * PI)
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*
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* \remark It is safe to pass the same array in lsf and lsp parameters
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*/
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void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf);
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/**
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* \brief LSP to LP conversion (3.2.6 of G.729)
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* \param lp [out] decoded LP coefficients (-0x8000 <= (3.12) < 0x8000)
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* \param lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
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*/
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void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp);
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/**
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* \brief Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729)
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* \param lp_1st [out] decoded LP coefficients for 1st subframe (-0x8000 <= (3.12) < 0x8000)
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* \param lp_2nd [out] decoded LP coefficients for second subframe (-0x8000 <= (3.12) < 0x8000)
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* \param lsp_2nd LSP coefficients of the second subframe (-0x8000 <= (0.15) < 0x8000)
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* \param lsp_prev past LSP coefficients (-0x8000 <= (0.15) < 0x8000)
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*/
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void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev);
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#endif // FFMPEG_ACELP_LPC_H
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