git.sesse.net Git - ffmpeg/blob - 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 FFmpeg.
   8  *
   9  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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/attributes.h"
  32 #include "libavutil/internal.h"
  33
  34 #include "audiodsp.h"
  35 #include "internal.h"
  36 #include "ac3enc.h"
  37 #include "eac3enc.h"
  38
  39
  40 int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
  41 {
  42     int ch;
  43
  44     FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
  45                      sizeof(*s->windowed_samples), alloc_fail);
  46     FF_ALLOC_ARRAY_OR_GOTO(s->avctx, s->planar_samples, s->channels, sizeof(*s->planar_samples),
  47                      alloc_fail);
  48     for (ch = 0; ch < s->channels; ch++) {
  49         FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
  50                           (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
  51                           alloc_fail);
  52     }
  53
  54     return 0;
  55 alloc_fail:
  56     return AVERROR(ENOMEM);
  57 }
  58
  59
  60 /*
  61  * Copy input samples.
  62  * Channels are reordered from FFmpeg's default order to AC-3 order.
  63  */
  64 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
  65 {
  66     int ch;
  67
  68     /* copy and remap input samples */
  69     for (ch = 0; ch < s->channels; ch++) {
  70         /* copy last 256 samples of previous frame to the start of the current frame */
  71         memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
  72                AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
  73
  74         /* copy new samples for current frame */
  75         memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
  76                samples[s->channel_map[ch]],
  77                AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
  78     }
  79 }
  80
  81
  82 /*
  83  * Apply the MDCT to input samples to generate frequency coefficients.
  84  * This applies the KBD window and normalizes the input to reduce precision
  85  * loss due to fixed-point calculations.
  86  */
  87 static void apply_mdct(AC3EncodeContext *s)
  88 {
  89     int blk, ch;
  90
  91     for (ch = 0; ch < s->channels; ch++) {
  92         for (blk = 0; blk < s->num_blocks; blk++) {
  93             AC3Block *block = &s->blocks[blk];
  94             const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
  95
  96 #if CONFIG_AC3ENC_FLOAT
  97             s->fdsp->vector_fmul(s->windowed_samples, input_samples,
  98                                 s->mdct_window, AC3_WINDOW_SIZE);
  99 #else
 100             s->ac3dsp.apply_window_int16(s->windowed_samples, input_samples,
 101                                          s->mdct_window, AC3_WINDOW_SIZE);
 102
 103             if (s->fixed_point)
 104                 block->coeff_shift[ch+1] = normalize_samples(s);
 105 #endif
 106
 107             s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
 108                                s->windowed_samples);
 109         }
 110     }
 111 }
 112
 113
 114 /*
 115  * Calculate coupling channel and coupling coordinates.
 116  */
 117 static void apply_channel_coupling(AC3EncodeContext *s)
 118 {
 119     LOCAL_ALIGNED_16(CoefType, cpl_coords,      [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 120 #if CONFIG_AC3ENC_FLOAT
 121     LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 122 #else
 123     int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
 124 #endif
 125     int av_uninit(blk), ch, bnd, i, j;
 126     CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
 127     int cpl_start, num_cpl_coefs;
 128
 129     memset(cpl_coords,       0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 130 #if CONFIG_AC3ENC_FLOAT
 131     memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 132 #endif
 133
 134     /* align start to 16-byte boundary. align length to multiple of 32.
 135         note: coupling start bin % 4 will always be 1 */
 136     cpl_start     = s->start_freq[CPL_CH] - 1;
 137     num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
 138     cpl_start     = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
 139
 140     /* calculate coupling channel from fbw channels */
 141     for (blk = 0; blk < s->num_blocks; blk++) {
 142         AC3Block *block = &s->blocks[blk];
 143         CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
 144         if (!block->cpl_in_use)
 145             continue;
 146         memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
 147         for (ch = 1; ch <= s->fbw_channels; ch++) {
 148             CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
 149             if (!block->channel_in_cpl[ch])
 150                 continue;
 151             for (i = 0; i < num_cpl_coefs; i++)
 152                 cpl_coef[i] += ch_coef[i];
 153         }
 154
 155         /* coefficients must be clipped in order to be encoded */
 156         clip_coefficients(&s->adsp, cpl_coef, num_cpl_coefs);
 157     }
 158
 159     /* calculate energy in each band in coupling channel and each fbw channel */
 160     /* TODO: possibly use SIMD to speed up energy calculation */
 161     bnd = 0;
 162     i = s->start_freq[CPL_CH];
 163     while (i < s->cpl_end_freq) {
 164         int band_size = s->cpl_band_sizes[bnd];
 165         for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
 166             for (blk = 0; blk < s->num_blocks; blk++) {
 167                 AC3Block *block = &s->blocks[blk];
 168                 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
 169                     continue;
 170                 for (j = 0; j < band_size; j++) {
 171                     CoefType v = block->mdct_coef[ch][i+j];
 172                     MAC_COEF(energy[blk][ch][bnd], v, v);
 173                 }
 174             }
 175         }
 176         i += band_size;
 177         bnd++;
 178     }
 179
 180     /* calculate coupling coordinates for all blocks for all channels */
 181     for (blk = 0; blk < s->num_blocks; blk++) {
 182         AC3Block *block  = &s->blocks[blk];
 183         if (!block->cpl_in_use)
 184             continue;
 185         for (ch = 1; ch <= s->fbw_channels; ch++) {
 186             if (!block->channel_in_cpl[ch])
 187                 continue;
 188             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 189                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
 190                                                           energy[blk][CPL_CH][bnd]);
 191             }
 192         }
 193     }
 194
 195     /* determine which blocks to send new coupling coordinates for */
 196     for (blk = 0; blk < s->num_blocks; blk++) {
 197         AC3Block *block  = &s->blocks[blk];
 198         AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
 199
 200         memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
 201
 202         if (block->cpl_in_use) {
 203             /* send new coordinates if this is the first block, if previous
 204              * block did not use coupling but this block does, the channels
 205              * using coupling has changed from the previous block, or the
 206              * coordinate difference from the last block for any channel is
 207              * greater than a threshold value. */
 208             if (blk == 0 || !block0->cpl_in_use) {
 209                 for (ch = 1; ch <= s->fbw_channels; ch++)
 210                     block->new_cpl_coords[ch] = 1;
 211             } else {
 212                 for (ch = 1; ch <= s->fbw_channels; ch++) {
 213                     if (!block->channel_in_cpl[ch])
 214                         continue;
 215                     if (!block0->channel_in_cpl[ch]) {
 216                         block->new_cpl_coords[ch] = 1;
 217                     } else {
 218                         CoefSumType coord_diff = 0;
 219                         for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 220                             coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
 221                                                 cpl_coords[blk  ][ch][bnd]);
 222                         }
 223                         coord_diff /= s->num_cpl_bands;
 224                         if (coord_diff > NEW_CPL_COORD_THRESHOLD)
 225                             block->new_cpl_coords[ch] = 1;
 226                     }
 227                 }
 228             }
 229         }
 230     }
 231
 232     /* calculate final coupling coordinates, taking into account reusing of
 233        coordinates in successive blocks */
 234     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 235         blk = 0;
 236         while (blk < s->num_blocks) {
 237             int av_uninit(blk1);
 238             AC3Block *block  = &s->blocks[blk];
 239
 240             if (!block->cpl_in_use) {
 241                 blk++;
 242                 continue;
 243             }
 244
 245             for (ch = 1; ch <= s->fbw_channels; ch++) {
 246                 CoefSumType energy_ch, energy_cpl;
 247                 if (!block->channel_in_cpl[ch])
 248                     continue;
 249                 energy_cpl = energy[blk][CPL_CH][bnd];
 250                 energy_ch = energy[blk][ch][bnd];
 251                 blk1 = blk+1;
 252                 while (blk1 < s->num_blocks && !s->blocks[blk1].new_cpl_coords[ch]) {
 253                     if (s->blocks[blk1].cpl_in_use) {
 254                         energy_cpl += energy[blk1][CPL_CH][bnd];
 255                         energy_ch += energy[blk1][ch][bnd];
 256                     }
 257                     blk1++;
 258                 }
 259                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
 260             }
 261             blk = blk1;
 262         }
 263     }
 264
 265     /* calculate exponents/mantissas for coupling coordinates */
 266     for (blk = 0; blk < s->num_blocks; blk++) {
 267         AC3Block *block = &s->blocks[blk];
 268         if (!block->cpl_in_use)
 269             continue;
 270
 271 #if CONFIG_AC3ENC_FLOAT
 272         s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
 273                                    cpl_coords[blk][1],
 274                                    s->fbw_channels * 16);
 275 #endif
 276         s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
 277                                     fixed_cpl_coords[blk][1],
 278                                     s->fbw_channels * 16);
 279
 280         for (ch = 1; ch <= s->fbw_channels; ch++) {
 281             int bnd, min_exp, max_exp, master_exp;
 282
 283             if (!block->new_cpl_coords[ch])
 284                 continue;
 285
 286             /* determine master exponent */
 287             min_exp = max_exp = block->cpl_coord_exp[ch][0];
 288             for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
 289                 int exp = block->cpl_coord_exp[ch][bnd];
 290                 min_exp = FFMIN(exp, min_exp);
 291                 max_exp = FFMAX(exp, max_exp);
 292             }
 293             master_exp = ((max_exp - 15) + 2) / 3;
 294             master_exp = FFMAX(master_exp, 0);
 295             while (min_exp < master_exp * 3)
 296                 master_exp--;
 297             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 298                 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
 299                                                         master_exp * 3, 0, 15);
 300             }
 301             block->cpl_master_exp[ch] = master_exp;
 302
 303             /* quantize mantissas */
 304             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 305                 int cpl_exp  = block->cpl_coord_exp[ch][bnd];
 306                 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
 307                 if (cpl_exp == 15)
 308                     cpl_mant >>= 1;
 309                 else
 310                     cpl_mant -= 16;
 311
 312                 block->cpl_coord_mant[ch][bnd] = cpl_mant;
 313             }
 314         }
 315     }
 316
 317     if (CONFIG_EAC3_ENCODER && s->eac3)
 318         ff_eac3_set_cpl_states(s);
 319 }
 320
 321
 322 /*
 323  * Determine rematrixing flags for each block and band.
 324  */
 325 static void compute_rematrixing_strategy(AC3EncodeContext *s)
 326 {
 327     int nb_coefs;
 328     int blk, bnd;
 329     AC3Block *block, *block0 = NULL;
 330
 331     if (s->channel_mode != AC3_CHMODE_STEREO)
 332         return;
 333
 334     for (blk = 0; blk < s->num_blocks; blk++) {
 335         block = &s->blocks[blk];
 336         block->new_rematrixing_strategy = !blk;
 337
 338         block->num_rematrixing_bands = 4;
 339         if (block->cpl_in_use) {
 340             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
 341             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
 342             if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
 343                 block->new_rematrixing_strategy = 1;
 344         }
 345         nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
 346
 347         if (!s->rematrixing_enabled) {
 348             block0 = block;
 349             continue;
 350         }
 351
 352         for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
 353             /* calculate sum of squared coeffs for one band in one block */
 354             int start = ff_ac3_rematrix_band_tab[bnd];
 355             int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
 356             CoefSumType sum[4];
 357             sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
 358                                  block->mdct_coef[2] + start, end - start);
 359
 360             /* compare sums to determine if rematrixing will be used for this band */
 361             if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
 362                 block->rematrixing_flags[bnd] = 1;
 363             else
 364                 block->rematrixing_flags[bnd] = 0;
 365
 366             /* determine if new rematrixing flags will be sent */
 367             if (blk &&
 368                 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
 369                 block->new_rematrixing_strategy = 1;
 370             }
 371         }
 372         block0 = block;
 373     }
 374 }
 375
 376
 377 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
 378                            const AVFrame *frame, int *got_packet_ptr)
 379 {
 380     AC3EncodeContext *s = avctx->priv_data;
 381     int ret;
 382
 383     if (s->options.allow_per_frame_metadata) {
 384         ret = ff_ac3_validate_metadata(s);
 385         if (ret)
 386             return ret;
 387     }
 388
 389     if (s->bit_alloc.sr_code == 1 || s->eac3)
 390         ff_ac3_adjust_frame_size(s);
 391
 392     copy_input_samples(s, (SampleType **)frame->extended_data);
 393
 394     apply_mdct(s);
 395
 396     if (s->fixed_point)
 397         scale_coefficients(s);
 398
 399     clip_coefficients(&s->adsp, s->blocks[0].mdct_coef[1],
 400                       AC3_MAX_COEFS * s->num_blocks * s->channels);
 401
 402     s->cpl_on = s->cpl_enabled;
 403     ff_ac3_compute_coupling_strategy(s);
 404
 405     if (s->cpl_on)
 406         apply_channel_coupling(s);
 407
 408     compute_rematrixing_strategy(s);
 409
 410     if (!s->fixed_point)
 411         scale_coefficients(s);
 412
 413     ff_ac3_apply_rematrixing(s);
 414
 415     ff_ac3_process_exponents(s);
 416
 417     ret = ff_ac3_compute_bit_allocation(s);
 418     if (ret) {
 419         av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
 420         return ret;
 421     }
 422
 423     ff_ac3_group_exponents(s);
 424
 425     ff_ac3_quantize_mantissas(s);
 426
 427     if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size, 0)) < 0)
 428         return ret;
 429     ff_ac3_output_frame(s, avpkt->data);
 430
 431     if (frame->pts != AV_NOPTS_VALUE)
 432         avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->initial_padding);
 433
 434     *got_packet_ptr = 1;
 435     return 0;
 436 }