2 * LSP routines for ACELP-based codecs
4 * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet (QCELP decoder)
5 * Copyright (c) 2008 Vladimir Voroshilov
7 * This file is part of FFmpeg.
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.
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.
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
30 #include "celp_math.h"
32 void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
36 /* sort lsfq in ascending order. float bubble agorithm,
37 O(n) if data already sorted, O(n^2) - otherwise */
38 for(i=0; i<lp_order-1; i++)
39 for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
40 FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
42 for(i=0; i<lp_order; i++)
44 lsfq[i] = FFMAX(lsfq[i], lsfq_min);
45 lsfq_min = lsfq[i] + lsfq_min_distance;
47 lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ?
50 void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size)
54 for (i = 0; i < size; i++)
55 prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing);
58 void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
62 /* Convert LSF to LSP, lsp=cos(lsf) */
63 for(i=0; i<lp_order; i++)
64 // 20861 = 2.0 / PI in (0.15)
65 lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
69 * \brief decodes polynomial coefficients from LSP
70 * \param f [out] decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
71 * \param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)
73 static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
77 f[0] = 0x400000; // 1.0 in (3.22)
78 f[1] = -lsp[0] << 8; // *2 and (0.15) -> (3.22)
80 for(i=2; i<=lp_half_order; i++)
84 f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
86 f[1] -= lsp[2*i-2] << 8;
90 void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
93 int f1[lp_half_order+1]; // (3.22)
94 int f2[lp_half_order+1]; // (3.22)
96 lsp2poly(f1, lsp , lp_half_order);
97 lsp2poly(f2, lsp+1, lp_half_order);
99 /* 3.2.6 of G.729, Equations 25 and 26*/
101 for(i=1; i<lp_half_order+1; i++)
103 int ff1 = f1[i] + f1[i-1]; // (3.22)
104 int ff2 = f2[i] - f2[i-1]; // (3.22)
106 ff1 += 1 << 10; // for rounding
107 lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
108 lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
112 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)
114 int16_t lsp_1st[lp_order]; // (0.15)
117 /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
118 for(i=0; i<lp_order; i++)
120 lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1);
122 lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
125 ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
127 /* LSP values for second subframe (3.2.5 of G.729)*/
128 ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
131 void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order)
138 for(i=2; i<=lp_half_order; i++)
140 double val = -2 * lsp[2*i];
141 f[i] = val * f[i-1] + 2*f[i-2];
143 f[j] += f[j-1] * val + f[j-2];
148 void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
150 double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
151 float *lpc2 = lpc + (lp_half_order << 1) - 1;
153 assert(lp_half_order <= MAX_LP_HALF_ORDER);
155 ff_lsp2polyf(lsp, pa, lp_half_order);
156 ff_lsp2polyf(lsp + 1, qa, lp_half_order);
158 while (lp_half_order--) {
159 double paf = pa[lp_half_order+1] + pa[lp_half_order];
160 double qaf = qa[lp_half_order+1] - qa[lp_half_order];
162 lpc [ lp_half_order] = 0.5*(paf+qaf);
163 lpc2[-lp_half_order] = 0.5*(paf-qaf);
167 void ff_sort_nearly_sorted_floats(float *vals, int len)
171 for (i = 0; i < len - 1; i++)
172 for (j = i; j >= 0 && vals[j] > vals[j+1]; j--)
173 FFSWAP(float, vals[j], vals[j+1]);