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 /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */
  40
  41 static void scale_coefficients(AC3EncodeContext *s);
  42
  43 static int normalize_samples(AC3EncodeContext *s);
  44
  45 static void clip_coefficients(AudioDSPContext *adsp, CoefType *coef,
  46                               unsigned int len);
  47
  48 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);
  49
  50 static void sum_square_butterfly(AC3EncodeContext *s, CoefSumType sum[4],
  51                                  const CoefType *coef0, const CoefType *coef1,
  52                                  int len);
  53
  54 int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
  55 {
  56     int ch;
  57
  58     FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
  59                      sizeof(*s->windowed_samples), alloc_fail);
  60     FF_ALLOC_ARRAY_OR_GOTO(s->avctx, s->planar_samples, s->channels, sizeof(*s->planar_samples),
  61                      alloc_fail);
  62     for (ch = 0; ch < s->channels; ch++) {
  63         FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
  64                           (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
  65                           alloc_fail);
  66     }
  67
  68     return 0;
  69 alloc_fail:
  70     return AVERROR(ENOMEM);
  71 }
  72
  73
  74 /*
  75  * Copy input samples.
  76  * Channels are reordered from FFmpeg's default order to AC-3 order.
  77  */
  78 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
  79 {
  80     int ch;
  81
  82     /* copy and remap input samples */
  83     for (ch = 0; ch < s->channels; ch++) {
  84         /* copy last 256 samples of previous frame to the start of the current frame */
  85         memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
  86                AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
  87
  88         /* copy new samples for current frame */
  89         memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
  90                samples[s->channel_map[ch]],
  91                AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
  92     }
  93 }
  94
  95
  96 /*
  97  * Apply the MDCT to input samples to generate frequency coefficients.
  98  * This applies the KBD window and normalizes the input to reduce precision
  99  * loss due to fixed-point calculations.
 100  */
 101 static void apply_mdct(AC3EncodeContext *s)
 102 {
 103     int blk, ch;
 104
 105     for (ch = 0; ch < s->channels; ch++) {
 106         for (blk = 0; blk < s->num_blocks; blk++) {
 107             AC3Block *block = &s->blocks[blk];
 108             const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
 109
 110 #if CONFIG_AC3ENC_FLOAT
 111             s->fdsp->vector_fmul(s->windowed_samples, input_samples,
 112                                 s->mdct_window, AC3_WINDOW_SIZE);
 113 #else
 114             s->ac3dsp.apply_window_int16(s->windowed_samples, input_samples,
 115                                          s->mdct_window, AC3_WINDOW_SIZE);
 116 #endif
 117
 118             if (s->fixed_point)
 119                 block->coeff_shift[ch+1] = normalize_samples(s);
 120
 121             s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
 122                                s->windowed_samples);
 123         }
 124     }
 125 }
 126
 127
 128 /*
 129  * Calculate coupling channel and coupling coordinates.
 130  */
 131 static void apply_channel_coupling(AC3EncodeContext *s)
 132 {
 133     LOCAL_ALIGNED_16(CoefType, cpl_coords,      [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 134 #if CONFIG_AC3ENC_FLOAT
 135     LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 136 #else
 137     int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
 138 #endif
 139     int av_uninit(blk), ch, bnd, i, j;
 140     CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
 141     int cpl_start, num_cpl_coefs;
 142
 143     memset(cpl_coords,       0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 144 #if CONFIG_AC3ENC_FLOAT
 145     memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 146 #endif
 147
 148     /* align start to 16-byte boundary. align length to multiple of 32.
 149         note: coupling start bin % 4 will always be 1 */
 150     cpl_start     = s->start_freq[CPL_CH] - 1;
 151     num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
 152     cpl_start     = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
 153
 154     /* calculate coupling channel from fbw channels */
 155     for (blk = 0; blk < s->num_blocks; blk++) {
 156         AC3Block *block = &s->blocks[blk];
 157         CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
 158         if (!block->cpl_in_use)
 159             continue;
 160         memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
 161         for (ch = 1; ch <= s->fbw_channels; ch++) {
 162             CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
 163             if (!block->channel_in_cpl[ch])
 164                 continue;
 165             for (i = 0; i < num_cpl_coefs; i++)
 166                 cpl_coef[i] += ch_coef[i];
 167         }
 168
 169         /* coefficients must be clipped in order to be encoded */
 170         clip_coefficients(&s->adsp, cpl_coef, num_cpl_coefs);
 171     }
 172
 173     /* calculate energy in each band in coupling channel and each fbw channel */
 174     /* TODO: possibly use SIMD to speed up energy calculation */
 175     bnd = 0;
 176     i = s->start_freq[CPL_CH];
 177     while (i < s->cpl_end_freq) {
 178         int band_size = s->cpl_band_sizes[bnd];
 179         for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
 180             for (blk = 0; blk < s->num_blocks; blk++) {
 181                 AC3Block *block = &s->blocks[blk];
 182                 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
 183                     continue;
 184                 for (j = 0; j < band_size; j++) {
 185                     CoefType v = block->mdct_coef[ch][i+j];
 186                     MAC_COEF(energy[blk][ch][bnd], v, v);
 187                 }
 188             }
 189         }
 190         i += band_size;
 191         bnd++;
 192     }
 193
 194     /* calculate coupling coordinates for all blocks for all channels */
 195     for (blk = 0; blk < s->num_blocks; blk++) {
 196         AC3Block *block  = &s->blocks[blk];
 197         if (!block->cpl_in_use)
 198             continue;
 199         for (ch = 1; ch <= s->fbw_channels; ch++) {
 200             if (!block->channel_in_cpl[ch])
 201                 continue;
 202             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 203                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
 204                                                           energy[blk][CPL_CH][bnd]);
 205             }
 206         }
 207     }
 208
 209     /* determine which blocks to send new coupling coordinates for */
 210     for (blk = 0; blk < s->num_blocks; blk++) {
 211         AC3Block *block  = &s->blocks[blk];
 212         AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
 213
 214         memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
 215
 216         if (block->cpl_in_use) {
 217             /* send new coordinates if this is the first block, if previous
 218              * block did not use coupling but this block does, the channels
 219              * using coupling has changed from the previous block, or the
 220              * coordinate difference from the last block for any channel is
 221              * greater than a threshold value. */
 222             if (blk == 0 || !block0->cpl_in_use) {
 223                 for (ch = 1; ch <= s->fbw_channels; ch++)
 224                     block->new_cpl_coords[ch] = 1;
 225             } else {
 226                 for (ch = 1; ch <= s->fbw_channels; ch++) {
 227                     if (!block->channel_in_cpl[ch])
 228                         continue;
 229                     if (!block0->channel_in_cpl[ch]) {
 230                         block->new_cpl_coords[ch] = 1;
 231                     } else {
 232                         CoefSumType coord_diff = 0;
 233                         for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 234                             coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
 235                                                 cpl_coords[blk  ][ch][bnd]);
 236                         }
 237                         coord_diff /= s->num_cpl_bands;
 238                         if (coord_diff > NEW_CPL_COORD_THRESHOLD)
 239                             block->new_cpl_coords[ch] = 1;
 240                     }
 241                 }
 242             }
 243         }
 244     }
 245
 246     /* calculate final coupling coordinates, taking into account reusing of
 247        coordinates in successive blocks */
 248     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 249         blk = 0;
 250         while (blk < s->num_blocks) {
 251             int av_uninit(blk1);
 252             AC3Block *block  = &s->blocks[blk];
 253
 254             if (!block->cpl_in_use) {
 255                 blk++;
 256                 continue;
 257             }
 258
 259             for (ch = 1; ch <= s->fbw_channels; ch++) {
 260                 CoefSumType energy_ch, energy_cpl;
 261                 if (!block->channel_in_cpl[ch])
 262                     continue;
 263                 energy_cpl = energy[blk][CPL_CH][bnd];
 264                 energy_ch = energy[blk][ch][bnd];
 265                 blk1 = blk+1;
 266                 while (blk1 < s->num_blocks && !s->blocks[blk1].new_cpl_coords[ch]) {
 267                     if (s->blocks[blk1].cpl_in_use) {
 268                         energy_cpl += energy[blk1][CPL_CH][bnd];
 269                         energy_ch += energy[blk1][ch][bnd];
 270                     }
 271                     blk1++;
 272                 }
 273                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
 274             }
 275             blk = blk1;
 276         }
 277     }
 278
 279     /* calculate exponents/mantissas for coupling coordinates */
 280     for (blk = 0; blk < s->num_blocks; blk++) {
 281         AC3Block *block = &s->blocks[blk];
 282         if (!block->cpl_in_use)
 283             continue;
 284
 285 #if CONFIG_AC3ENC_FLOAT
 286         s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
 287                                    cpl_coords[blk][1],
 288                                    s->fbw_channels * 16);
 289 #endif
 290         s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
 291                                     fixed_cpl_coords[blk][1],
 292                                     s->fbw_channels * 16);
 293
 294         for (ch = 1; ch <= s->fbw_channels; ch++) {
 295             int bnd, min_exp, max_exp, master_exp;
 296
 297             if (!block->new_cpl_coords[ch])
 298                 continue;
 299
 300             /* determine master exponent */
 301             min_exp = max_exp = block->cpl_coord_exp[ch][0];
 302             for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
 303                 int exp = block->cpl_coord_exp[ch][bnd];
 304                 min_exp = FFMIN(exp, min_exp);
 305                 max_exp = FFMAX(exp, max_exp);
 306             }
 307             master_exp = ((max_exp - 15) + 2) / 3;
 308             master_exp = FFMAX(master_exp, 0);
 309             while (min_exp < master_exp * 3)
 310                 master_exp--;
 311             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 312                 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
 313                                                         master_exp * 3, 0, 15);
 314             }
 315             block->cpl_master_exp[ch] = master_exp;
 316
 317             /* quantize mantissas */
 318             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 319                 int cpl_exp  = block->cpl_coord_exp[ch][bnd];
 320                 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
 321                 if (cpl_exp == 15)
 322                     cpl_mant >>= 1;
 323                 else
 324                     cpl_mant -= 16;
 325
 326                 block->cpl_coord_mant[ch][bnd] = cpl_mant;
 327             }
 328         }
 329     }
 330
 331     if (CONFIG_EAC3_ENCODER && s->eac3)
 332         ff_eac3_set_cpl_states(s);
 333 }
 334
 335
 336 /*
 337  * Determine rematrixing flags for each block and band.
 338  */
 339 static void compute_rematrixing_strategy(AC3EncodeContext *s)
 340 {
 341     int nb_coefs;
 342     int blk, bnd;
 343     AC3Block *block, *block0 = NULL;
 344
 345     if (s->channel_mode != AC3_CHMODE_STEREO)
 346         return;
 347
 348     for (blk = 0; blk < s->num_blocks; blk++) {
 349         block = &s->blocks[blk];
 350         block->new_rematrixing_strategy = !blk;
 351
 352         block->num_rematrixing_bands = 4;
 353         if (block->cpl_in_use) {
 354             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
 355             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
 356             if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
 357                 block->new_rematrixing_strategy = 1;
 358         }
 359         nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
 360
 361         if (!s->rematrixing_enabled) {
 362             block0 = block;
 363             continue;
 364         }
 365
 366         for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
 367             /* calculate sum of squared coeffs for one band in one block */
 368             int start = ff_ac3_rematrix_band_tab[bnd];
 369             int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
 370             CoefSumType sum[4];
 371             sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
 372                                  block->mdct_coef[2] + start, end - start);
 373
 374             /* compare sums to determine if rematrixing will be used for this band */
 375             if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
 376                 block->rematrixing_flags[bnd] = 1;
 377             else
 378                 block->rematrixing_flags[bnd] = 0;
 379
 380             /* determine if new rematrixing flags will be sent */
 381             if (blk &&
 382                 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
 383                 block->new_rematrixing_strategy = 1;
 384             }
 385         }
 386         block0 = block;
 387     }
 388 }
 389
 390
 391 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
 392                            const AVFrame *frame, int *got_packet_ptr)
 393 {
 394     AC3EncodeContext *s = avctx->priv_data;
 395     int ret;
 396
 397     if (s->options.allow_per_frame_metadata) {
 398         ret = ff_ac3_validate_metadata(s);
 399         if (ret)
 400             return ret;
 401     }
 402
 403     if (s->bit_alloc.sr_code == 1 || s->eac3)
 404         ff_ac3_adjust_frame_size(s);
 405
 406     copy_input_samples(s, (SampleType **)frame->extended_data);
 407
 408     apply_mdct(s);
 409
 410     if (s->fixed_point)
 411         scale_coefficients(s);
 412
 413     clip_coefficients(&s->adsp, s->blocks[0].mdct_coef[1],
 414                       AC3_MAX_COEFS * s->num_blocks * s->channels);
 415
 416     s->cpl_on = s->cpl_enabled;
 417     ff_ac3_compute_coupling_strategy(s);
 418
 419     if (s->cpl_on)
 420         apply_channel_coupling(s);
 421
 422     compute_rematrixing_strategy(s);
 423
 424     if (!s->fixed_point)
 425         scale_coefficients(s);
 426
 427     ff_ac3_apply_rematrixing(s);
 428
 429     ff_ac3_process_exponents(s);
 430
 431     ret = ff_ac3_compute_bit_allocation(s);
 432     if (ret) {
 433         av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
 434         return ret;
 435     }
 436
 437     ff_ac3_group_exponents(s);
 438
 439     ff_ac3_quantize_mantissas(s);
 440
 441     if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size, 0)) < 0)
 442         return ret;
 443     ff_ac3_output_frame(s, avpkt->data);
 444
 445     if (frame->pts != AV_NOPTS_VALUE)
 446         avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->initial_padding);
 447
 448     *got_packet_ptr = 1;
 449     return 0;
 450 }