Libav
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00001 /* 00002 * LSP routines for ACELP-based codecs 00003 * 00004 * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet (QCELP decoder) 00005 * Copyright (c) 2008 Vladimir Voroshilov 00006 * 00007 * This file is part of FFmpeg. 00008 * 00009 * FFmpeg is free software; you can redistribute it and/or 00010 * modify it under the terms of the GNU Lesser General Public 00011 * License as published by the Free Software Foundation; either 00012 * version 2.1 of the License, or (at your option) any later version. 00013 * 00014 * FFmpeg is distributed in the hope that it will be useful, 00015 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00016 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00017 * Lesser General Public License for more details. 00018 * 00019 * You should have received a copy of the GNU Lesser General Public 00020 * License along with FFmpeg; if not, write to the Free Software 00021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00022 */ 00023 00024 #include <inttypes.h> 00025 00026 #include "avcodec.h" 00027 #define FRAC_BITS 14 00028 #include "mathops.h" 00029 #include "lsp.h" 00030 #include "celp_math.h" 00031 00032 void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order) 00033 { 00034 int i, j; 00035 00036 /* sort lsfq in ascending order. float bubble agorithm, 00037 O(n) if data already sorted, O(n^2) - otherwise */ 00038 for(i=0; i<lp_order-1; i++) 00039 for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--) 00040 FFSWAP(int16_t, lsfq[j], lsfq[j+1]); 00041 00042 for(i=0; i<lp_order; i++) 00043 { 00044 lsfq[i] = FFMAX(lsfq[i], lsfq_min); 00045 lsfq_min = lsfq[i] + lsfq_min_distance; 00046 } 00047 lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ? 00048 } 00049 00050 void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size) 00051 { 00052 int i; 00053 float prev = 0.0; 00054 for (i = 0; i < size; i++) 00055 prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing); 00056 } 00057 00058 void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order) 00059 { 00060 int i; 00061 00062 /* Convert LSF to LSP, lsp=cos(lsf) */ 00063 for(i=0; i<lp_order; i++) 00064 // 20861 = 2.0 / PI in (0.15) 00065 lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14) 00066 } 00067 00073 static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order) 00074 { 00075 int i, j; 00076 00077 f[0] = 0x400000; // 1.0 in (3.22) 00078 f[1] = -lsp[0] << 8; // *2 and (0.15) -> (3.22) 00079 00080 for(i=2; i<=lp_half_order; i++) 00081 { 00082 f[i] = f[i-2]; 00083 for(j=i; j>1; j--) 00084 f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2]; 00085 00086 f[1] -= lsp[2*i-2] << 8; 00087 } 00088 } 00089 00090 void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order) 00091 { 00092 int i; 00093 int f1[lp_half_order+1]; // (3.22) 00094 int f2[lp_half_order+1]; // (3.22) 00095 00096 lsp2poly(f1, lsp , lp_half_order); 00097 lsp2poly(f2, lsp+1, lp_half_order); 00098 00099 /* 3.2.6 of G.729, Equations 25 and 26*/ 00100 lp[0] = 4096; 00101 for(i=1; i<lp_half_order+1; i++) 00102 { 00103 int ff1 = f1[i] + f1[i-1]; // (3.22) 00104 int ff2 = f2[i] - f2[i-1]; // (3.22) 00105 00106 ff1 += 1 << 10; // for rounding 00107 lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12) 00108 lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12) 00109 } 00110 } 00111 00112 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) 00113 { 00114 int16_t lsp_1st[lp_order]; // (0.15) 00115 int i; 00116 00117 /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/ 00118 for(i=0; i<lp_order; i++) 00119 #ifdef G729_BITEXACT 00120 lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1); 00121 #else 00122 lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1; 00123 #endif 00124 00125 ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1); 00126 00127 /* LSP values for second subframe (3.2.5 of G.729)*/ 00128 ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1); 00129 } 00130 00131 void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order) 00132 { 00133 int i, j; 00134 00135 f[0] = 1.0; 00136 f[1] = -2 * lsp[0]; 00137 lsp -= 2; 00138 for(i=2; i<=lp_half_order; i++) 00139 { 00140 double val = -2 * lsp[2*i]; 00141 f[i] = val * f[i-1] + 2*f[i-2]; 00142 for(j=i-1; j>1; j--) 00143 f[j] += f[j-1] * val + f[j-2]; 00144 f[1] += val; 00145 } 00146 } 00147 00148 void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order) 00149 { 00150 double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1]; 00151 float *lpc2 = lpc + (lp_half_order << 1) - 1; 00152 00153 assert(lp_half_order <= MAX_LP_HALF_ORDER); 00154 00155 ff_lsp2polyf(lsp, pa, lp_half_order); 00156 ff_lsp2polyf(lsp + 1, qa, lp_half_order); 00157 00158 while (lp_half_order--) { 00159 double paf = pa[lp_half_order+1] + pa[lp_half_order]; 00160 double qaf = qa[lp_half_order+1] - qa[lp_half_order]; 00161 00162 lpc [ lp_half_order] = 0.5*(paf+qaf); 00163 lpc2[-lp_half_order] = 0.5*(paf-qaf); 00164 } 00165 } 00166 00167 void ff_sort_nearly_sorted_floats(float *vals, int len) 00168 { 00169 int i,j; 00170 00171 for (i = 0; i < len - 1; i++) 00172 for (j = i; j >= 0 && vals[j] > vals[j+1]; j--) 00173 FFSWAP(float, vals[j], vals[j+1]); 00174 }