libavcodec/g723_1.c

   1 /*
   2  * G.723.1 compatible decoder
   3  * Copyright (c) 2006 Benjamin Larsson
   4  * Copyright (c) 2010 Mohamed Naufal Basheer
   5  *
   6  * This file is part of Libav.
   7  *
   8  * Libav is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * Libav is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with Libav; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <stdint.h>
  24
  25 #include "libavutil/common.h"
  26
  27 #include "acelp_vectors.h"
  28 #include "avcodec.h"
  29 #include "celp_math.h"
  30 #include "g723_1.h"
  31
  32 int ff_g723_1_scale_vector(int16_t *dst, const int16_t *vector, int length)
  33 {
  34     int bits, max = 0;
  35     int i;
  36
  37     for (i = 0; i < length; i++)
  38         max |= FFABS(vector[i]);
  39
  40     max  = FFMIN(max, 0x7FFF);
  41     bits = ff_g723_1_normalize_bits(max, 15);
  42
  43     for (i = 0; i < length; i++)
  44         dst[i] = vector[i] << bits >> 3;
  45
  46     return bits - 3;
  47 }
  48
  49 int ff_g723_1_normalize_bits(int num, int width)
  50 {
  51     return width - av_log2(num) - 1;
  52 }
  53
  54 int ff_g723_1_dot_product(const int16_t *a, const int16_t *b, int length)
  55 {
  56     int sum = ff_dot_product(a, b, length);
  57     return av_sat_add32(sum, sum);
  58 }
  59
  60 void ff_g723_1_get_residual(int16_t *residual, int16_t *prev_excitation,
  61                             int lag)
  62 {
  63     int offset = PITCH_MAX - PITCH_ORDER / 2 - lag;
  64     int i;
  65
  66     residual[0] = prev_excitation[offset];
  67     residual[1] = prev_excitation[offset + 1];
  68
  69     offset += 2;
  70     for (i = 2; i < SUBFRAME_LEN + PITCH_ORDER - 1; i++)
  71         residual[i] = prev_excitation[offset + (i - 2) % lag];
  72 }
  73
  74 void ff_g723_1_gen_dirac_train(int16_t *buf, int pitch_lag)
  75 {
  76     int16_t vector[SUBFRAME_LEN];
  77     int i, j;
  78
  79     memcpy(vector, buf, SUBFRAME_LEN * sizeof(*vector));
  80     for (i = pitch_lag; i < SUBFRAME_LEN; i += pitch_lag) {
  81         for (j = 0; j < SUBFRAME_LEN - i; j++)
  82             buf[i + j] += vector[j];
  83     }
  84 }
  85
  86 void ff_g723_1_gen_acb_excitation(int16_t *vector, int16_t *prev_excitation,
  87                                   int pitch_lag, G723_1_Subframe *subfrm,
  88                                   enum Rate cur_rate)
  89 {
  90     int16_t residual[SUBFRAME_LEN + PITCH_ORDER - 1];
  91     const int16_t *cb_ptr;
  92     int lag = pitch_lag + subfrm->ad_cb_lag - 1;
  93
  94     int i;
  95     int sum;
  96
  97     ff_g723_1_get_residual(residual, prev_excitation, lag);
  98
  99     /* Select quantization table */
 100     if (cur_rate == RATE_6300 && pitch_lag < SUBFRAME_LEN - 2)
 101         cb_ptr = adaptive_cb_gain85;
 102     else
 103         cb_ptr = adaptive_cb_gain170;
 104
 105     /* Calculate adaptive vector */
 106     cb_ptr += subfrm->ad_cb_gain * 20;
 107     for (i = 0; i < SUBFRAME_LEN; i++) {
 108         sum       = ff_g723_1_dot_product(residual + i, cb_ptr, PITCH_ORDER);
 109         vector[i] = av_sat_dadd32(1 << 15, sum) >> 16;
 110     }
 111 }
 112
 113 /**
 114  * Convert LSP frequencies to LPC coefficients.
 115  *
 116  * @param lpc buffer for LPC coefficients
 117  */
 118 static void lsp2lpc(int16_t *lpc)
 119 {
 120     int f1[LPC_ORDER / 2 + 1];
 121     int f2[LPC_ORDER / 2 + 1];
 122     int i, j;
 123
 124     /* Calculate negative cosine */
 125     for (j = 0; j < LPC_ORDER; j++) {
 126         int index  = (lpc[j] >> 7) & 0x1FF;
 127         int offset = lpc[j] & 0x7f;
 128         int temp1  = cos_tab[index] << 16;
 129         int temp2  = (cos_tab[index + 1] - cos_tab[index]) *
 130                      ((offset << 8) + 0x80) << 1;
 131
 132         lpc[j] = -(av_sat_dadd32(1 << 15, temp1 + temp2) >> 16);
 133     }
 134
 135     /*
 136      * Compute sum and difference polynomial coefficients
 137      * (bitexact alternative to lsp2poly() in lsp.c)
 138      */
 139     /* Initialize with values in Q28 */
 140     f1[0] = 1 << 28;
 141     f1[1] = (lpc[0] << 14) + (lpc[2] << 14);
 142     f1[2] = lpc[0] * lpc[2] + (2 << 28);
 143
 144     f2[0] = 1 << 28;
 145     f2[1] = (lpc[1] << 14) + (lpc[3] << 14);
 146     f2[2] = lpc[1] * lpc[3] + (2 << 28);
 147
 148     /*
 149      * Calculate and scale the coefficients by 1/2 in
 150      * each iteration for a final scaling factor of Q25
 151      */
 152     for (i = 2; i < LPC_ORDER / 2; i++) {
 153         f1[i + 1] = f1[i - 1] + MULL2(f1[i], lpc[2 * i]);
 154         f2[i + 1] = f2[i - 1] + MULL2(f2[i], lpc[2 * i + 1]);
 155
 156         for (j = i; j >= 2; j--) {
 157             f1[j] = MULL2(f1[j - 1], lpc[2 * i]) +
 158                     (f1[j] >> 1) + (f1[j - 2] >> 1);
 159             f2[j] = MULL2(f2[j - 1], lpc[2 * i + 1]) +
 160                     (f2[j] >> 1) + (f2[j - 2] >> 1);
 161         }
 162
 163         f1[0] >>= 1;
 164         f2[0] >>= 1;
 165         f1[1]   = ((lpc[2 * i]     << 16 >> i) + f1[1]) >> 1;
 166         f2[1]   = ((lpc[2 * i + 1] << 16 >> i) + f2[1]) >> 1;
 167     }
 168
 169     /* Convert polynomial coefficients to LPC coefficients */
 170     for (i = 0; i < LPC_ORDER / 2; i++) {
 171         int64_t ff1 = f1[i + 1] + f1[i];
 172         int64_t ff2 = f2[i + 1] - f2[i];
 173
 174         lpc[i]                 = av_clipl_int32(((ff1 + ff2) << 3) +
 175                                                 (1 << 15)) >> 16;
 176         lpc[LPC_ORDER - i - 1] = av_clipl_int32(((ff1 - ff2) << 3) +
 177                                                 (1 << 15)) >> 16;
 178     }
 179 }
 180
 181 void ff_g723_1_lsp_interpolate(int16_t *lpc, int16_t *cur_lsp,
 182                                int16_t *prev_lsp)
 183 {
 184     int i;
 185     int16_t *lpc_ptr = lpc;
 186
 187     /* cur_lsp * 0.25 + prev_lsp * 0.75 */
 188     ff_acelp_weighted_vector_sum(lpc, cur_lsp, prev_lsp,
 189                                  4096, 12288, 1 << 13, 14, LPC_ORDER);
 190     ff_acelp_weighted_vector_sum(lpc + LPC_ORDER, cur_lsp, prev_lsp,
 191                                  8192, 8192, 1 << 13, 14, LPC_ORDER);
 192     ff_acelp_weighted_vector_sum(lpc + 2 * LPC_ORDER, cur_lsp, prev_lsp,
 193                                  12288, 4096, 1 << 13, 14, LPC_ORDER);
 194     memcpy(lpc + 3 * LPC_ORDER, cur_lsp, LPC_ORDER * sizeof(*lpc));
 195
 196     for (i = 0; i < SUBFRAMES; i++) {
 197         lsp2lpc(lpc_ptr);
 198         lpc_ptr += LPC_ORDER;
 199     }
 200 }
 201
 202 void ff_g723_1_inverse_quant(int16_t *cur_lsp, int16_t *prev_lsp,
 203                              uint8_t *lsp_index, int bad_frame)
 204 {
 205     int min_dist, pred;
 206     int i, j, temp, stable;
 207
 208     /* Check for frame erasure */
 209     if (!bad_frame) {
 210         min_dist     = 0x100;
 211         pred         = 12288;
 212     } else {
 213         min_dist     = 0x200;
 214         pred         = 23552;
 215         lsp_index[0] = lsp_index[1] = lsp_index[2] = 0;
 216     }
 217
 218     /* Get the VQ table entry corresponding to the transmitted index */
 219     cur_lsp[0] = lsp_band0[lsp_index[0]][0];
 220     cur_lsp[1] = lsp_band0[lsp_index[0]][1];
 221     cur_lsp[2] = lsp_band0[lsp_index[0]][2];
 222     cur_lsp[3] = lsp_band1[lsp_index[1]][0];
 223     cur_lsp[4] = lsp_band1[lsp_index[1]][1];
 224     cur_lsp[5] = lsp_band1[lsp_index[1]][2];
 225     cur_lsp[6] = lsp_band2[lsp_index[2]][0];
 226     cur_lsp[7] = lsp_band2[lsp_index[2]][1];
 227     cur_lsp[8] = lsp_band2[lsp_index[2]][2];
 228     cur_lsp[9] = lsp_band2[lsp_index[2]][3];
 229
 230     /* Add predicted vector & DC component to the previously quantized vector */
 231     for (i = 0; i < LPC_ORDER; i++) {
 232         temp        = ((prev_lsp[i] - dc_lsp[i]) * pred + (1 << 14)) >> 15;
 233         cur_lsp[i] += dc_lsp[i] + temp;
 234     }
 235
 236     for (i = 0; i < LPC_ORDER; i++) {
 237         cur_lsp[0]             = FFMAX(cur_lsp[0], 0x180);
 238         cur_lsp[LPC_ORDER - 1] = FFMIN(cur_lsp[LPC_ORDER - 1], 0x7e00);
 239
 240         /* Stability check */
 241         for (j = 1; j < LPC_ORDER; j++) {
 242             temp = min_dist + cur_lsp[j - 1] - cur_lsp[j];
 243             if (temp > 0) {
 244                 temp >>= 1;
 245                 cur_lsp[j - 1] -= temp;
 246                 cur_lsp[j]     += temp;
 247             }
 248         }
 249         stable = 1;
 250         for (j = 1; j < LPC_ORDER; j++) {
 251             temp = cur_lsp[j - 1] + min_dist - cur_lsp[j] - 4;
 252             if (temp > 0) {
 253                 stable = 0;
 254                 break;
 255             }
 256         }
 257         if (stable)
 258             break;
 259     }
 260     if (!stable)
 261         memcpy(cur_lsp, prev_lsp, LPC_ORDER * sizeof(*cur_lsp));
 262 }