libavcodec/lsp.c

   1 /*
   2  * LSP routines for ACELP-based codecs
   3  *
   4  * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet (QCELP decoder)
   5  * Copyright (c) 2008 Vladimir Voroshilov
   6  *
   7  * This file is part of FFmpeg.
   8  *
   9  * FFmpeg is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * FFmpeg is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with FFmpeg; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include <math.h>
  25
  26 #include "config.h"
  27
  28 #define FRAC_BITS 14
  29 #include "libavutil/macros.h"
  30 #include "mathops.h"
  31 #include "lsp.h"
  32 #if ARCH_MIPS
  33 #include "libavcodec/mips/lsp_mips.h"
  34 #endif /* ARCH_MIPS */
  35 #include "libavutil/avassert.h"
  36
  37 void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
  38 {
  39     int i, j;
  40
  41     /* sort lsfq in ascending order. float bubble algorithm,
  42        O(n) if data already sorted, O(n^2) - otherwise */
  43     for(i=0; i<lp_order-1; i++)
  44         for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
  45             FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
  46
  47     for(i=0; i<lp_order; i++)
  48     {
  49         lsfq[i] = FFMAX(lsfq[i], lsfq_min);
  50         lsfq_min = lsfq[i] + lsfq_min_distance;
  51     }
  52     lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ?
  53 }
  54
  55 void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size)
  56 {
  57     int i;
  58     float prev = 0.0;
  59     for (i = 0; i < size; i++)
  60         prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing);
  61 }
  62
  63
  64 /* Cosine table: base_cos[i] = (1 << 15) * cos(i * PI / 64) */
  65 static const int16_t tab_cos[65] =
  66 {
  67   32767,  32738,  32617,  32421,  32145,  31793,  31364,  30860,
  68   30280,  29629,  28905,  28113,  27252,  26326,  25336,  24285,
  69   23176,  22011,  20793,  19525,  18210,  16851,  15451,  14014,
  70   12543,  11043,   9515,   7965,   6395,   4810,   3214,   1609,
  71       1,  -1607,  -3211,  -4808,  -6393,  -7962,  -9513, -11040,
  72  -12541, -14012, -15449, -16848, -18207, -19523, -20791, -22009,
  73  -23174, -24283, -25334, -26324, -27250, -28111, -28904, -29627,
  74  -30279, -30858, -31363, -31792, -32144, -32419, -32616, -32736, -32768,
  75 };
  76
  77 static int16_t ff_cos(uint16_t arg)
  78 {
  79     uint8_t offset= arg;
  80     uint8_t ind = arg >> 8;
  81
  82     av_assert2(arg <= 0x3fff);
  83
  84     return tab_cos[ind] + (offset * (tab_cos[ind+1] - tab_cos[ind]) >> 8);
  85 }
  86
  87 void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
  88 {
  89     int i;
  90
  91     /* Convert LSF to LSP, lsp=cos(lsf) */
  92     for(i=0; i<lp_order; i++)
  93         // 20861 = 2.0 / PI in (0.15)
  94         lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
  95 }
  96
  97 void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order)
  98 {
  99     int i;
 100
 101     for(i = 0; i < lp_order; i++)
 102         lsp[i] = cos(2.0 * M_PI * lsf[i]);
 103 }
 104
 105 /**
 106  * @brief decodes polynomial coefficients from LSP
 107  * @param[out] f decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
 108  * @param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)
 109  */
 110 static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
 111 {
 112     int i, j;
 113
 114     f[0] = 0x400000;          // 1.0 in (3.22)
 115     f[1] = -lsp[0] * 256;     // *2 and (0.15) -> (3.22)
 116
 117     for(i=2; i<=lp_half_order; i++)
 118     {
 119         f[i] = f[i-2];
 120         for(j=i; j>1; j--)
 121             f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
 122
 123         f[1] -= lsp[2*i-2] * 256;
 124     }
 125 }
 126
 127 #ifndef lsp2polyf
 128 /**
 129  * Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients
 130  * needed for LSP to LPC conversion.
 131  * We only need to calculate the 6 first elements of the polynomial.
 132  *
 133  * @param lsp line spectral pairs in cosine domain
 134  * @param[out] f polynomial input/output as a vector
 135  *
 136  * TIA/EIA/IS-733 2.4.3.3.5-1/2
 137  */
 138 static void lsp2polyf(const double *lsp, double *f, int lp_half_order)
 139 {
 140     f[0] = 1.0;
 141     f[1] = -2 * lsp[0];
 142     lsp -= 2;
 143     for (int i = 2; i <= lp_half_order; i++) {
 144         double val = -2 * lsp[2*i];
 145         f[i] = val * f[i-1] + 2*f[i-2];
 146         for (int j = i-1; j > 1; j--)
 147             f[j] += f[j-1] * val + f[j-2];
 148         f[1] += val;
 149     }
 150 }
 151 #endif /* lsp2polyf */
 152
 153 void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
 154 {
 155     int i;
 156     int f1[MAX_LP_HALF_ORDER+1]; // (3.22)
 157     int f2[MAX_LP_HALF_ORDER+1]; // (3.22)
 158
 159     lsp2poly(f1, lsp  , lp_half_order);
 160     lsp2poly(f2, lsp+1, lp_half_order);
 161
 162     /* 3.2.6 of G.729, Equations 25 and  26*/
 163     lp[0] = 4096;
 164     for(i=1; i<lp_half_order+1; i++)
 165     {
 166         int ff1 = f1[i] + f1[i-1]; // (3.22)
 167         int ff2 = f2[i] - f2[i-1]; // (3.22)
 168
 169         ff1 += 1 << 10; // for rounding
 170         lp[i]    = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
 171         lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
 172     }
 173 }
 174
 175 void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order)
 176 {
 177     int lp_half_order = lp_order >> 1;
 178     double buf[MAX_LP_HALF_ORDER + 1];
 179     double pa[MAX_LP_HALF_ORDER + 1];
 180     double *qa = buf + 1;
 181     int i,j;
 182
 183     qa[-1] = 0.0;
 184
 185     lsp2polyf(lsp    , pa, lp_half_order    );
 186     lsp2polyf(lsp + 1, qa, lp_half_order - 1);
 187
 188     for (i = 1, j = lp_order - 1; i < lp_half_order; i++, j--) {
 189         double paf =  pa[i]            * (1 + lsp[lp_order - 1]);
 190         double qaf = (qa[i] - qa[i-2]) * (1 - lsp[lp_order - 1]);
 191         lp[i-1]  = (paf + qaf) * 0.5;
 192         lp[j-1]  = (paf - qaf) * 0.5;
 193     }
 194
 195     lp[lp_half_order - 1] = (1.0 + lsp[lp_order - 1]) *
 196         pa[lp_half_order] * 0.5;
 197
 198     lp[lp_order - 1] = lsp[lp_order - 1];
 199 }
 200
 201 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)
 202 {
 203     int16_t lsp_1st[MAX_LP_ORDER]; // (0.15)
 204     int i;
 205
 206     /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
 207     for(i=0; i<lp_order; i++)
 208 #ifdef G729_BITEXACT
 209         lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1);
 210 #else
 211         lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
 212 #endif
 213
 214     ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
 215
 216     /* LSP values for second subframe (3.2.5 of G.729)*/
 217     ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
 218 }
 219
 220 void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
 221 {
 222     double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
 223     float *lpc2 = lpc + (lp_half_order << 1) - 1;
 224
 225     av_assert2(lp_half_order <= MAX_LP_HALF_ORDER);
 226
 227     lsp2polyf(lsp,     pa, lp_half_order);
 228     lsp2polyf(lsp + 1, qa, lp_half_order);
 229
 230     while (lp_half_order--) {
 231         double paf = pa[lp_half_order+1] + pa[lp_half_order];
 232         double qaf = qa[lp_half_order+1] - qa[lp_half_order];
 233
 234         lpc [ lp_half_order] = 0.5*(paf+qaf);
 235         lpc2[-lp_half_order] = 0.5*(paf-qaf);
 236     }
 237 }
 238
 239 void ff_sort_nearly_sorted_floats(float *vals, int len)
 240 {
 241     int i,j;
 242
 243     for (i = 0; i < len - 1; i++)
 244         for (j = i; j >= 0 && vals[j] > vals[j+1]; j--)
 245             FFSWAP(float, vals[j], vals[j+1]);
 246 }