libavcodec/ac3enc_template.c

   1 /*
   2  * AC-3 encoder float/fixed template
   3  * Copyright (c) 2000 Fabrice Bellard
   4  * Copyright (c) 2006-2011 Justin Ruggles <justin.ruggles@gmail.com>
   5  * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
   6  *
   7  * This file is part of Libav.
   8  *
   9  * Libav is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * Libav is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with Libav; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 /**
  25  * @file
  26  * AC-3 encoder float/fixed template
  27  */
  28
  29 #include <stdint.h>
  30
  31 #include "libavutil/internal.h"
  32
  33 /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */
  34
  35 static void scale_coefficients(AC3EncodeContext *s);
  36
  37 static void apply_window(void *dsp, SampleType *output,
  38                          const SampleType *input, const SampleType *window,
  39                          unsigned int len);
  40
  41 static int normalize_samples(AC3EncodeContext *s);
  42
  43 static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len);
  44
  45 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);
  46
  47
  48 int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
  49 {
  50     int ch;
  51
  52     FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
  53                      sizeof(*s->windowed_samples), alloc_fail);
  54     FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
  55                      alloc_fail);
  56     for (ch = 0; ch < s->channels; ch++) {
  57         FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
  58                           (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
  59                           alloc_fail);
  60     }
  61
  62     return 0;
  63 alloc_fail:
  64     return AVERROR(ENOMEM);
  65 }
  66
  67
  68 /*
  69  * Copy input samples.
  70  * Channels are reordered from Libav's default order to AC-3 order.
  71  */
  72 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
  73 {
  74     int ch;
  75
  76     /* copy and remap input samples */
  77     for (ch = 0; ch < s->channels; ch++) {
  78         /* copy last 256 samples of previous frame to the start of the current frame */
  79         memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
  80                AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
  81
  82         /* copy new samples for current frame */
  83         memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
  84                samples[s->channel_map[ch]],
  85                AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
  86     }
  87 }
  88
  89
  90 /*
  91  * Apply the MDCT to input samples to generate frequency coefficients.
  92  * This applies the KBD window and normalizes the input to reduce precision
  93  * loss due to fixed-point calculations.
  94  */
  95 static void apply_mdct(AC3EncodeContext *s)
  96 {
  97     int blk, ch;
  98
  99     for (ch = 0; ch < s->channels; ch++) {
 100         for (blk = 0; blk < s->num_blocks; blk++) {
 101             AC3Block *block = &s->blocks[blk];
 102             const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
 103
 104 #if CONFIG_AC3ENC_FLOAT
 105             apply_window(&s->fdsp, s->windowed_samples, input_samples,
 106                          s->mdct_window, AC3_WINDOW_SIZE);
 107 #else
 108             apply_window(&s->dsp, s->windowed_samples, input_samples,
 109                          s->mdct_window, AC3_WINDOW_SIZE);
 110 #endif
 111
 112             if (s->fixed_point)
 113                 block->coeff_shift[ch+1] = normalize_samples(s);
 114
 115             s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
 116                                s->windowed_samples);
 117         }
 118     }
 119 }
 120
 121
 122 /*
 123  * Calculate coupling channel and coupling coordinates.
 124  */
 125 static void apply_channel_coupling(AC3EncodeContext *s)
 126 {
 127     LOCAL_ALIGNED_16(CoefType, cpl_coords,      [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 128 #if CONFIG_AC3ENC_FLOAT
 129     LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 130 #else
 131     int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
 132 #endif
 133     int blk, ch, bnd, i, j;
 134     CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
 135     int cpl_start, num_cpl_coefs;
 136
 137     memset(cpl_coords,       0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 138 #if CONFIG_AC3ENC_FLOAT
 139     memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 140 #endif
 141
 142     /* align start to 16-byte boundary. align length to multiple of 32.
 143         note: coupling start bin % 4 will always be 1 */
 144     cpl_start     = s->start_freq[CPL_CH] - 1;
 145     num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
 146     cpl_start     = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
 147
 148     /* calculate coupling channel from fbw channels */
 149     for (blk = 0; blk < s->num_blocks; blk++) {
 150         AC3Block *block = &s->blocks[blk];
 151         CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
 152         if (!block->cpl_in_use)
 153             continue;
 154         memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
 155         for (ch = 1; ch <= s->fbw_channels; ch++) {
 156             CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
 157             if (!block->channel_in_cpl[ch])
 158                 continue;
 159             for (i = 0; i < num_cpl_coefs; i++)
 160                 cpl_coef[i] += ch_coef[i];
 161         }
 162
 163         /* coefficients must be clipped in order to be encoded */
 164         clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
 165     }
 166
 167     /* calculate energy in each band in coupling channel and each fbw channel */
 168     /* TODO: possibly use SIMD to speed up energy calculation */
 169     bnd = 0;
 170     i = s->start_freq[CPL_CH];
 171     while (i < s->cpl_end_freq) {
 172         int band_size = s->cpl_band_sizes[bnd];
 173         for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
 174             for (blk = 0; blk < s->num_blocks; blk++) {
 175                 AC3Block *block = &s->blocks[blk];
 176                 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
 177                     continue;
 178                 for (j = 0; j < band_size; j++) {
 179                     CoefType v = block->mdct_coef[ch][i+j];
 180                     MAC_COEF(energy[blk][ch][bnd], v, v);
 181                 }
 182             }
 183         }
 184         i += band_size;
 185         bnd++;
 186     }
 187
 188     /* calculate coupling coordinates for all blocks for all channels */
 189     for (blk = 0; blk < s->num_blocks; blk++) {
 190         AC3Block *block  = &s->blocks[blk];
 191         if (!block->cpl_in_use)
 192             continue;
 193         for (ch = 1; ch <= s->fbw_channels; ch++) {
 194             if (!block->channel_in_cpl[ch])
 195                 continue;
 196             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 197                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
 198                                                           energy[blk][CPL_CH][bnd]);
 199             }
 200         }
 201     }
 202
 203     /* determine which blocks to send new coupling coordinates for */
 204     for (blk = 0; blk < s->num_blocks; blk++) {
 205         AC3Block *block  = &s->blocks[blk];
 206         AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
 207
 208         memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
 209
 210         if (block->cpl_in_use) {
 211             /* send new coordinates if this is the first block, if previous
 212              * block did not use coupling but this block does, the channels
 213              * using coupling has changed from the previous block, or the
 214              * coordinate difference from the last block for any channel is
 215              * greater than a threshold value. */
 216             if (blk == 0 || !block0->cpl_in_use) {
 217                 for (ch = 1; ch <= s->fbw_channels; ch++)
 218                     block->new_cpl_coords[ch] = 1;
 219             } else {
 220                 for (ch = 1; ch <= s->fbw_channels; ch++) {
 221                     if (!block->channel_in_cpl[ch])
 222                         continue;
 223                     if (!block0->channel_in_cpl[ch]) {
 224                         block->new_cpl_coords[ch] = 1;
 225                     } else {
 226                         CoefSumType coord_diff = 0;
 227                         for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 228                             coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
 229                                                 cpl_coords[blk  ][ch][bnd]);
 230                         }
 231                         coord_diff /= s->num_cpl_bands;
 232                         if (coord_diff > NEW_CPL_COORD_THRESHOLD)
 233                             block->new_cpl_coords[ch] = 1;
 234                     }
 235                 }
 236             }
 237         }
 238     }
 239
 240     /* calculate final coupling coordinates, taking into account reusing of
 241        coordinates in successive blocks */
 242     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 243         blk = 0;
 244         while (blk < s->num_blocks) {
 245             int av_uninit(blk1);
 246             AC3Block *block  = &s->blocks[blk];
 247
 248             if (!block->cpl_in_use) {
 249                 blk++;
 250                 continue;
 251             }
 252
 253             for (ch = 1; ch <= s->fbw_channels; ch++) {
 254                 CoefSumType energy_ch, energy_cpl;
 255                 if (!block->channel_in_cpl[ch])
 256                     continue;
 257                 energy_cpl = energy[blk][CPL_CH][bnd];
 258                 energy_ch = energy[blk][ch][bnd];
 259                 blk1 = blk+1;
 260                 while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {
 261                     if (s->blocks[blk1].cpl_in_use) {
 262                         energy_cpl += energy[blk1][CPL_CH][bnd];
 263                         energy_ch += energy[blk1][ch][bnd];
 264                     }
 265                     blk1++;
 266                 }
 267                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
 268             }
 269             blk = blk1;
 270         }
 271     }
 272
 273     /* calculate exponents/mantissas for coupling coordinates */
 274     for (blk = 0; blk < s->num_blocks; blk++) {
 275         AC3Block *block = &s->blocks[blk];
 276         if (!block->cpl_in_use)
 277             continue;
 278
 279 #if CONFIG_AC3ENC_FLOAT
 280         s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
 281                                    cpl_coords[blk][1],
 282                                    s->fbw_channels * 16);
 283 #endif
 284         s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
 285                                     fixed_cpl_coords[blk][1],
 286                                     s->fbw_channels * 16);
 287
 288         for (ch = 1; ch <= s->fbw_channels; ch++) {
 289             int bnd, min_exp, max_exp, master_exp;
 290
 291             if (!block->new_cpl_coords[ch])
 292                 continue;
 293
 294             /* determine master exponent */
 295             min_exp = max_exp = block->cpl_coord_exp[ch][0];
 296             for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
 297                 int exp = block->cpl_coord_exp[ch][bnd];
 298                 min_exp = FFMIN(exp, min_exp);
 299                 max_exp = FFMAX(exp, max_exp);
 300             }
 301             master_exp = ((max_exp - 15) + 2) / 3;
 302             master_exp = FFMAX(master_exp, 0);
 303             while (min_exp < master_exp * 3)
 304                 master_exp--;
 305             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 306                 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
 307                                                         master_exp * 3, 0, 15);
 308             }
 309             block->cpl_master_exp[ch] = master_exp;
 310
 311             /* quantize mantissas */
 312             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 313                 int cpl_exp  = block->cpl_coord_exp[ch][bnd];
 314                 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
 315                 if (cpl_exp == 15)
 316                     cpl_mant >>= 1;
 317                 else
 318                     cpl_mant -= 16;
 319
 320                 block->cpl_coord_mant[ch][bnd] = cpl_mant;
 321             }
 322         }
 323     }
 324
 325     if (CONFIG_EAC3_ENCODER && s->eac3)
 326         ff_eac3_set_cpl_states(s);
 327 }
 328
 329
 330 /*
 331  * Determine rematrixing flags for each block and band.
 332  */
 333 static void compute_rematrixing_strategy(AC3EncodeContext *s)
 334 {
 335     int nb_coefs;
 336     int blk, bnd, i;
 337     AC3Block *block, *block0;
 338
 339     if (s->channel_mode != AC3_CHMODE_STEREO)
 340         return;
 341
 342     for (blk = 0; blk < s->num_blocks; blk++) {
 343         block = &s->blocks[blk];
 344         block->new_rematrixing_strategy = !blk;
 345
 346         block->num_rematrixing_bands = 4;
 347         if (block->cpl_in_use) {
 348             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
 349             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
 350             if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
 351                 block->new_rematrixing_strategy = 1;
 352         }
 353         nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
 354
 355         if (!s->rematrixing_enabled) {
 356             block0 = block;
 357             continue;
 358         }
 359
 360         for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
 361             /* calculate calculate sum of squared coeffs for one band in one block */
 362             int start = ff_ac3_rematrix_band_tab[bnd];
 363             int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
 364             CoefSumType sum[4] = {0,};
 365             for (i = start; i < end; i++) {
 366                 CoefType lt = block->mdct_coef[1][i];
 367                 CoefType rt = block->mdct_coef[2][i];
 368                 CoefType md = lt + rt;
 369                 CoefType sd = lt - rt;
 370                 MAC_COEF(sum[0], lt, lt);
 371                 MAC_COEF(sum[1], rt, rt);
 372                 MAC_COEF(sum[2], md, md);
 373                 MAC_COEF(sum[3], sd, sd);
 374             }
 375
 376             /* compare sums to determine if rematrixing will be used for this band */
 377             if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
 378                 block->rematrixing_flags[bnd] = 1;
 379             else
 380                 block->rematrixing_flags[bnd] = 0;
 381
 382             /* determine if new rematrixing flags will be sent */
 383             if (blk &&
 384                 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
 385                 block->new_rematrixing_strategy = 1;
 386             }
 387         }
 388         block0 = block;
 389     }
 390 }
 391
 392
 393 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
 394                            const AVFrame *frame, int *got_packet_ptr)
 395 {
 396     AC3EncodeContext *s = avctx->priv_data;
 397     int ret;
 398
 399     if (s->options.allow_per_frame_metadata) {
 400         ret = ff_ac3_validate_metadata(s);
 401         if (ret)
 402             return ret;
 403     }
 404
 405     if (s->bit_alloc.sr_code == 1 || s->eac3)
 406         ff_ac3_adjust_frame_size(s);
 407
 408     copy_input_samples(s, (SampleType **)frame->extended_data);
 409
 410     apply_mdct(s);
 411
 412     if (s->fixed_point)
 413         scale_coefficients(s);
 414
 415     clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
 416                       AC3_MAX_COEFS * s->num_blocks * s->channels);
 417
 418     s->cpl_on = s->cpl_enabled;
 419     ff_ac3_compute_coupling_strategy(s);
 420
 421     if (s->cpl_on)
 422         apply_channel_coupling(s);
 423
 424     compute_rematrixing_strategy(s);
 425
 426     if (!s->fixed_point)
 427         scale_coefficients(s);
 428
 429     ff_ac3_apply_rematrixing(s);
 430
 431     ff_ac3_process_exponents(s);
 432
 433     ret = ff_ac3_compute_bit_allocation(s);
 434     if (ret) {
 435         av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
 436         return ret;
 437     }
 438
 439     ff_ac3_group_exponents(s);
 440
 441     ff_ac3_quantize_mantissas(s);
 442
 443     if ((ret = ff_alloc_packet(avpkt, s->frame_size))) {
 444         av_log(avctx, AV_LOG_ERROR, "Error getting output packet\n");
 445         return ret;
 446     }
 447     ff_ac3_output_frame(s, avpkt->data);
 448
 449     if (frame->pts != AV_NOPTS_VALUE)
 450         avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);
 451
 452     *got_packet_ptr = 1;
 453     return 0;
 454 }