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120 lines
3.6 KiB
120 lines
3.6 KiB
/* |
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* LSP routines for ACELP-based codecs |
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* |
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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_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]) - 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[lp_half_order+1]; // (3.22) |
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int f2[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[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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