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ffmpeg / libavcodec / lsp.c @ 164d166e

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/*
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 * LSP routines for ACELP-based 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 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 "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_order-1; 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_order-1] = FFMIN(lsfq[lp_order-1], 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[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], FRAC_BITS) - f[j-2];
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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, 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[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[(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[i-1] + 2*f[i-2];
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        for(j=i-1; j>1; j--)
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            f[j] += f[j-1] * val + f[j-2];
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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*(paf-qaf);
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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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}