/* * LSP routines for ACELP-based codecs * * Copyright (c) 2008 Vladimir Voroshilov * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include <inttypes.h> #include "avcodec.h" #define FRAC_BITS 14 #include "mathops.h" #include "lsp.h" #include "celp_math.h" void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order) { int i, j; /* sort lsfq in ascending order. float bubble agorithm, O(n) if data already sorted, O(n^2) - otherwise */ for(i=0; i<lp_order-1; i++) for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--) FFSWAP(int16_t, lsfq[j], lsfq[j+1]); for(i=0; i<lp_order; i++) { lsfq[i] = FFMAX(lsfq[i], lsfq_min); lsfq_min = lsfq[i] + lsfq_min_distance; } lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ? } void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order) { int i; /* Convert LSF to LSP, lsp=cos(lsf) */ for(i=0; i<lp_order; i++) // 20861 = 2.0 / PI in (0.15) lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14) } /** * \brief decodes polynomial coefficients from LSP * \param f [out] decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff) * \param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff) */ static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order) { int i, j; f[0] = 0x400000; // 1.0 in (3.22) f[1] = -lsp[0] << 8; // *2 and (0.15) -> (3.22) for(i=2; i<=lp_half_order; i++) { f[i] = f[i-2]; for(j=i; j>1; j--) f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2]; f[1] -= lsp[2*i-2] << 8; } } void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order) { int i; int f1[lp_half_order+1]; // (3.22) int f2[lp_half_order+1]; // (3.22) lsp2poly(f1, lsp , lp_half_order); lsp2poly(f2, lsp+1, lp_half_order); /* 3.2.6 of G.729, Equations 25 and 26*/ lp[0] = 4096; for(i=1; i<lp_half_order+1; i++) { int ff1 = f1[i] + f1[i-1]; // (3.22) int ff2 = f2[i] - f2[i-1]; // (3.22) ff1 += 1 << 10; // for rounding lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12) lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12) } } 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) { int16_t lsp_1st[lp_order]; // (0.15) int i; /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/ for(i=0; i<lp_order; i++) #ifdef G729_BITEXACT lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1); #else lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1; #endif ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1); /* LSP values for second subframe (3.2.5 of G.729)*/ ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1); }