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 i, sum = 0;
  57
  58     for (i = 0; i < length; i++) {
  59         int prod = a[i] * b[i];
  60         sum = av_sat_dadd32(sum, prod);
  61     }
  62     return sum;
  63 }
  64
  65 void ff_g723_1_get_residual(int16_t *residual, int16_t *prev_excitation,
  66                             int lag)
  67 {
  68     int offset = PITCH_MAX - PITCH_ORDER / 2 - lag;
  69     int i;
  70
  71     residual[0] = prev_excitation[offset];
  72     residual[1] = prev_excitation[offset + 1];
  73
  74     offset += 2;
  75     for (i = 2; i < SUBFRAME_LEN + PITCH_ORDER - 1; i++)
  76         residual[i] = prev_excitation[offset + (i - 2) % lag];
  77 }
  78
  79 void ff_g723_1_gen_dirac_train(int16_t *buf, int pitch_lag)
  80 {
  81     int16_t vector[SUBFRAME_LEN];
  82     int i, j;
  83
  84     memcpy(vector, buf, SUBFRAME_LEN * sizeof(*vector));
  85     for (i = pitch_lag; i < SUBFRAME_LEN; i += pitch_lag) {
  86         for (j = 0; j < SUBFRAME_LEN - i; j++)
  87             buf[i + j] += vector[j];
  88     }
  89 }
  90
  91 void ff_g723_1_gen_acb_excitation(int16_t *vector, int16_t *prev_excitation,
  92                                   int pitch_lag, G723_1_Subframe *subfrm,
  93                                   enum Rate cur_rate)
  94 {
  95     int16_t residual[SUBFRAME_LEN + PITCH_ORDER - 1];
  96     const int16_t *cb_ptr;
  97     int lag = pitch_lag + subfrm->ad_cb_lag - 1;
  98
  99     int i;
 100     int sum;
 101
 102     ff_g723_1_get_residual(residual, prev_excitation, lag);
 103
 104     /* Select quantization table */
 105     if (cur_rate == RATE_6300 && pitch_lag < SUBFRAME_LEN - 2)
 106         cb_ptr = adaptive_cb_gain85;
 107     else
 108         cb_ptr = adaptive_cb_gain170;
 109
 110     /* Calculate adaptive vector */
 111     cb_ptr += subfrm->ad_cb_gain * 20;
 112     for (i = 0; i < SUBFRAME_LEN; i++) {
 113         sum       = ff_g723_1_dot_product(residual + i, cb_ptr, PITCH_ORDER);
 114         vector[i] = av_sat_dadd32(1 << 15, sum) >> 16;
 115     }
 116 }
 117
 118 /**
 119  * Convert LSP frequencies to LPC coefficients.
 120  *
 121  * @param lpc buffer for LPC coefficients
 122  */
 123 static void lsp2lpc(int16_t *lpc)
 124 {
 125     int f1[LPC_ORDER / 2 + 1];
 126     int f2[LPC_ORDER / 2 + 1];
 127     int i, j;
 128
 129     /* Calculate negative cosine */
 130     for (j = 0; j < LPC_ORDER; j++) {
 131         int index  = (lpc[j] >> 7) & 0x1FF;
 132         int offset = lpc[j] & 0x7f;
 133         int temp1  = cos_tab[index] << 16;
 134         int temp2  = (cos_tab[index + 1] - cos_tab[index]) *
 135                      ((offset << 8) + 0x80) << 1;
 136
 137         lpc[j] = -(av_sat_dadd32(1 << 15, temp1 + temp2) >> 16);
 138     }
 139
 140     /*
 141      * Compute sum and difference polynomial coefficients
 142      * (bitexact alternative to lsp2poly() in lsp.c)
 143      */
 144     /* Initialize with values in Q28 */
 145     f1[0] = 1 << 28;
 146     f1[1] = (lpc[0] << 14) + (lpc[2] << 14);
 147     f1[2] = lpc[0] * lpc[2] + (2 << 28);
 148
 149     f2[0] = 1 << 28;
 150     f2[1] = (lpc[1] << 14) + (lpc[3] << 14);
 151     f2[2] = lpc[1] * lpc[3] + (2 << 28);
 152
 153     /*
 154      * Calculate and scale the coefficients by 1/2 in
 155      * each iteration for a final scaling factor of Q25
 156      */
 157     for (i = 2; i < LPC_ORDER / 2; i++) {
 158         f1[i + 1] = f1[i - 1] + MULL2(f1[i], lpc[2 * i]);
 159         f2[i + 1] = f2[i - 1] + MULL2(f2[i], lpc[2 * i + 1]);
 160
 161         for (j = i; j >= 2; j--) {
 162             f1[j] = MULL2(f1[j - 1], lpc[2 * i]) +
 163                     (f1[j] >> 1) + (f1[j - 2] >> 1);
 164             f2[j] = MULL2(f2[j - 1], lpc[2 * i + 1]) +
 165                     (f2[j] >> 1) + (f2[j - 2] >> 1);
 166         }
 167
 168         f1[0] >>= 1;
 169         f2[0] >>= 1;
 170         f1[1]   = ((lpc[2 * i]     << 16 >> i) + f1[1]) >> 1;
 171         f2[1]   = ((lpc[2 * i + 1] << 16 >> i) + f2[1]) >> 1;
 172     }
 173
 174     /* Convert polynomial coefficients to LPC coefficients */
 175     for (i = 0; i < LPC_ORDER / 2; i++) {
 176         int64_t ff1 = f1[i + 1] + f1[i];
 177         int64_t ff2 = f2[i + 1] - f2[i];
 178
 179         lpc[i]                 = av_clipl_int32(((ff1 + ff2) << 3) +
 180                                                 (1 << 15)) >> 16;
 181         lpc[LPC_ORDER - i - 1] = av_clipl_int32(((ff1 - ff2) << 3) +
 182                                                 (1 << 15)) >> 16;
 183     }
 184 }
 185
 186 void ff_g723_1_lsp_interpolate(int16_t *lpc, int16_t *cur_lsp,
 187                                int16_t *prev_lsp)
 188 {
 189     int i;
 190     int16_t *lpc_ptr = lpc;
 191
 192     /* cur_lsp * 0.25 + prev_lsp * 0.75 */
 193     ff_acelp_weighted_vector_sum(lpc, cur_lsp, prev_lsp,
 194                                  4096, 12288, 1 << 13, 14, LPC_ORDER);
 195     ff_acelp_weighted_vector_sum(lpc + LPC_ORDER, cur_lsp, prev_lsp,
 196                                  8192, 8192, 1 << 13, 14, LPC_ORDER);
 197     ff_acelp_weighted_vector_sum(lpc + 2 * LPC_ORDER, cur_lsp, prev_lsp,
 198                                  12288, 4096, 1 << 13, 14, LPC_ORDER);
 199     memcpy(lpc + 3 * LPC_ORDER, cur_lsp, LPC_ORDER * sizeof(*lpc));
 200
 201     for (i = 0; i < SUBFRAMES; i++) {
 202         lsp2lpc(lpc_ptr);
 203         lpc_ptr += LPC_ORDER;
 204     }
 205 }
 206
 207 void ff_g723_1_inverse_quant(int16_t *cur_lsp, int16_t *prev_lsp,
 208                              uint8_t *lsp_index, int bad_frame)
 209 {
 210     int min_dist, pred;
 211     int i, j, temp, stable;
 212
 213     /* Check for frame erasure */
 214     if (!bad_frame) {
 215         min_dist     = 0x100;
 216         pred         = 12288;
 217     } else {
 218         min_dist     = 0x200;
 219         pred         = 23552;
 220         lsp_index[0] = lsp_index[1] = lsp_index[2] = 0;
 221     }
 222
 223     /* Get the VQ table entry corresponding to the transmitted index */
 224     cur_lsp[0] = lsp_band0[lsp_index[0]][0];
 225     cur_lsp[1] = lsp_band0[lsp_index[0]][1];
 226     cur_lsp[2] = lsp_band0[lsp_index[0]][2];
 227     cur_lsp[3] = lsp_band1[lsp_index[1]][0];
 228     cur_lsp[4] = lsp_band1[lsp_index[1]][1];
 229     cur_lsp[5] = lsp_band1[lsp_index[1]][2];
 230     cur_lsp[6] = lsp_band2[lsp_index[2]][0];
 231     cur_lsp[7] = lsp_band2[lsp_index[2]][1];
 232     cur_lsp[8] = lsp_band2[lsp_index[2]][2];
 233     cur_lsp[9] = lsp_band2[lsp_index[2]][3];
 234
 235     /* Add predicted vector & DC component to the previously quantized vector */
 236     for (i = 0; i < LPC_ORDER; i++) {
 237         temp        = ((prev_lsp[i] - dc_lsp[i]) * pred + (1 << 14)) >> 15;
 238         cur_lsp[i] += dc_lsp[i] + temp;
 239     }
 240
 241     for (i = 0; i < LPC_ORDER; i++) {
 242         cur_lsp[0]             = FFMAX(cur_lsp[0], 0x180);
 243         cur_lsp[LPC_ORDER - 1] = FFMIN(cur_lsp[LPC_ORDER - 1], 0x7e00);
 244
 245         /* Stability check */
 246         for (j = 1; j < LPC_ORDER; j++) {
 247             temp = min_dist + cur_lsp[j - 1] - cur_lsp[j];
 248             if (temp > 0) {
 249                 temp >>= 1;
 250                 cur_lsp[j - 1] -= temp;
 251                 cur_lsp[j]     += temp;
 252             }
 253         }
 254         stable = 1;
 255         for (j = 1; j < LPC_ORDER; j++) {
 256             temp = cur_lsp[j - 1] + min_dist - cur_lsp[j] - 4;
 257             if (temp > 0) {
 258                 stable = 0;
 259                 break;
 260             }
 261         }
 262         if (stable)
 263             break;
 264     }
 265     if (!stable)
 266         memcpy(cur_lsp, prev_lsp, LPC_ORDER * sizeof(*cur_lsp));
 267 }