ffmpeg / libavcodec / lsp.c @ 164d166e
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/*


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* LSP routines for ACELPbased codecs

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*

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* Copyright (c) 2007 Reynaldo H. Verdejo Pinochet (QCELP decoder)

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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 021101301 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 "celp_math.h" 
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void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order) 
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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<lp_order1; 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<lp_order; 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[lp_order1] = FFMIN(lsfq[lp_order1], lsfq_max);//Is warning required ? 
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} 
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void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size) 
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{ 
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int i;

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float prev = 0.0; 
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for (i = 0; i < size; i++) 
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prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing); 
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} 
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void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order) 
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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<lp_order; 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, int lp_half_order) 
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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<=lp_half_order; i++) 
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{ 
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f[i] = f[i2];

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for(j=i; j>1; j) 
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f[j] = MULL(f[j1], lsp[2*i2], FRAC_BITS)  f[j2]; 
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f[1] = lsp[2*i2] << 8; 
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} 
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} 
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void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order) 
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{ 
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int i;

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int f1[MAX_LP_HALF_ORDER+1]; // (3.22) 
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int f2[MAX_LP_HALF_ORDER+1]; // (3.22) 
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lsp2poly(f1, lsp , lp_half_order); 
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lsp2poly(f2, lsp+1, lp_half_order);

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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<lp_half_order+1; i++) 
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{ 
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int ff1 = f1[i] + f1[i1]; // (3.22) 
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int ff2 = f2[i]  f2[i1]; // (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[(lp_half_order << 1) + 1  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, int lp_order) 
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{ 
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int16_t lsp_1st[MAX_LP_ORDER]; // (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<lp_order; 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, lp_order >> 1);

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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, lp_order >> 1);

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} 
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void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order) 
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{ 
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int i, j;

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f[0] = 1.0; 
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f[1] = 2 * lsp[0]; 
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lsp = 2;

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for(i=2; i<=lp_half_order; i++) 
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{ 
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double val = 2 * lsp[2*i]; 
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f[i] = val * f[i1] + 2*f[i2]; 
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for(j=i1; j>1; j) 
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f[j] += f[j1] * val + f[j2]; 
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f[1] += val;

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} 
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} 
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void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order) 
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{ 
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double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1]; 
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float *lpc2 = lpc + (lp_half_order << 1)  1; 
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assert(lp_half_order <= MAX_LP_HALF_ORDER); 
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ff_lsp2polyf(lsp, pa, lp_half_order); 
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ff_lsp2polyf(lsp + 1, qa, lp_half_order);

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while (lp_half_order) {

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double paf = pa[lp_half_order+1] + pa[lp_half_order]; 
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double qaf = qa[lp_half_order+1]  qa[lp_half_order]; 
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lpc [ lp_half_order] = 0.5*(paf+qaf); 
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lpc2[lp_half_order] = 0.5*(pafqaf); 
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} 
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} 
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void ff_sort_nearly_sorted_floats(float *vals, int len) 
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{ 
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int i,j;

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for (i = 0; i < len  1; i++) 
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for (j = i; j >= 0 && vals[j] > vals[j+1]; j) 
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FFSWAP(float, vals[j], vals[j+1]); 
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} 