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
  32 /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */
  33
  34 static void scale_coefficients(AC3EncodeContext *s);
  35
  36 static void apply_window(void *dsp, SampleType *output,
  37                          const SampleType *input, const SampleType *window,
  38                          unsigned int len);
  39
  40 static int normalize_samples(AC3EncodeContext *s);
  41
  42 static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len);
  43
  44 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);
  45
  46 static void sum_square_butterfly(AC3EncodeContext *s, CoefSumType sum[4],
  47                                  const CoefType *coef0, const CoefType *coef1,
  48                                  int len);
  49
  50 int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
  51 {
  52     int ch;
  53
  54     FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
  55                      sizeof(*s->windowed_samples), alloc_fail);
  56     FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
  57                      alloc_fail);
  58     for (ch = 0; ch < s->channels; ch++) {
  59         FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
  60                           (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
  61                           alloc_fail);
  62     }
  63
  64     return 0;
  65 alloc_fail:
  66     return AVERROR(ENOMEM);
  67 }
  68
  69
  70 /*
  71  * Copy input samples.
  72  * Channels are reordered from FFmpeg's default order to AC-3 order.
  73  */
  74 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
  75 {
  76     int ch;
  77
  78     /* copy and remap input samples */
  79     for (ch = 0; ch < s->channels; ch++) {
  80         /* copy last 256 samples of previous frame to the start of the current frame */
  81         memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
  82                AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
  83
  84         /* copy new samples for current frame */
  85         memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
  86                samples[s->channel_map[ch]],
  87                AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
  88     }
  89 }
  90
  91
  92 /*
  93  * Apply the MDCT to input samples to generate frequency coefficients.
  94  * This applies the KBD window and normalizes the input to reduce precision
  95  * loss due to fixed-point calculations.
  96  */
  97 static void apply_mdct(AC3EncodeContext *s)
  98 {
  99     int blk, ch;
 100
 101     for (ch = 0; ch < s->channels; ch++) {
 102         for (blk = 0; blk < s->num_blocks; blk++) {
 103             AC3Block *block = &s->blocks[blk];
 104             const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
 105
 106 #if CONFIG_AC3ENC_FLOAT
 107             apply_window(&s->fdsp, s->windowed_samples, input_samples,
 108                          s->mdct_window, AC3_WINDOW_SIZE);
 109 #else
 110             apply_window(&s->dsp, s->windowed_samples, input_samples,
 111                          s->mdct_window, AC3_WINDOW_SIZE);
 112 #endif
 113
 114             if (s->fixed_point)
 115                 block->coeff_shift[ch+1] = normalize_samples(s);
 116
 117             s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
 118                                s->windowed_samples);
 119         }
 120     }
 121 }
 122
 123
 124 /*
 125  * Calculate coupling channel and coupling coordinates.
 126  */
 127 static void apply_channel_coupling(AC3EncodeContext *s)
 128 {
 129     LOCAL_ALIGNED_16(CoefType, cpl_coords,      [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 130 #if CONFIG_AC3ENC_FLOAT
 131     LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 132 #else
 133     int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
 134 #endif
 135     int blk, ch, bnd, i, j;
 136     CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
 137     int cpl_start, num_cpl_coefs;
 138
 139     memset(cpl_coords,       0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 140 #if CONFIG_AC3ENC_FLOAT
 141     memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 142 #endif
 143
 144     /* align start to 16-byte boundary. align length to multiple of 32.
 145         note: coupling start bin % 4 will always be 1 */
 146     cpl_start     = s->start_freq[CPL_CH] - 1;
 147     num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
 148     cpl_start     = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
 149
 150     /* calculate coupling channel from fbw channels */
 151     for (blk = 0; blk < s->num_blocks; blk++) {
 152         AC3Block *block = &s->blocks[blk];
 153         CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
 154         if (!block->cpl_in_use)
 155             continue;
 156         memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
 157         for (ch = 1; ch <= s->fbw_channels; ch++) {
 158             CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
 159             if (!block->channel_in_cpl[ch])
 160                 continue;
 161             for (i = 0; i < num_cpl_coefs; i++)
 162                 cpl_coef[i] += ch_coef[i];
 163         }
 164
 165         /* coefficients must be clipped in order to be encoded */
 166         clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
 167     }
 168
 169     /* calculate energy in each band in coupling channel and each fbw channel */
 170     /* TODO: possibly use SIMD to speed up energy calculation */
 171     bnd = 0;
 172     i = s->start_freq[CPL_CH];
 173     while (i < s->cpl_end_freq) {
 174         int band_size = s->cpl_band_sizes[bnd];
 175         for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
 176             for (blk = 0; blk < s->num_blocks; blk++) {
 177                 AC3Block *block = &s->blocks[blk];
 178                 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
 179                     continue;
 180                 for (j = 0; j < band_size; j++) {
 181                     CoefType v = block->mdct_coef[ch][i+j];
 182                     MAC_COEF(energy[blk][ch][bnd], v, v);
 183                 }
 184             }
 185         }
 186         i += band_size;
 187         bnd++;
 188     }
 189
 190     /* calculate coupling coordinates for all blocks for all channels */
 191     for (blk = 0; blk < s->num_blocks; blk++) {
 192         AC3Block *block  = &s->blocks[blk];
 193         if (!block->cpl_in_use)
 194             continue;
 195         for (ch = 1; ch <= s->fbw_channels; ch++) {
 196             if (!block->channel_in_cpl[ch])
 197                 continue;
 198             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 199                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
 200                                                           energy[blk][CPL_CH][bnd]);
 201             }
 202         }
 203     }
 204
 205     /* determine which blocks to send new coupling coordinates for */
 206     for (blk = 0; blk < s->num_blocks; blk++) {
 207         AC3Block *block  = &s->blocks[blk];
 208         AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
 209
 210         memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
 211
 212         if (block->cpl_in_use) {
 213             /* send new coordinates if this is the first block, if previous
 214              * block did not use coupling but this block does, the channels
 215              * using coupling has changed from the previous block, or the
 216              * coordinate difference from the last block for any channel is
 217              * greater than a threshold value. */
 218             if (blk == 0 || !block0->cpl_in_use) {
 219                 for (ch = 1; ch <= s->fbw_channels; ch++)
 220                     block->new_cpl_coords[ch] = 1;
 221             } else {
 222                 for (ch = 1; ch <= s->fbw_channels; ch++) {
 223                     if (!block->channel_in_cpl[ch])
 224                         continue;
 225                     if (!block0->channel_in_cpl[ch]) {
 226                         block->new_cpl_coords[ch] = 1;
 227                     } else {
 228                         CoefSumType coord_diff = 0;
 229                         for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 230                             coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
 231                                                 cpl_coords[blk  ][ch][bnd]);
 232                         }
 233                         coord_diff /= s->num_cpl_bands;
 234                         if (coord_diff > NEW_CPL_COORD_THRESHOLD)
 235                             block->new_cpl_coords[ch] = 1;
 236                     }
 237                 }
 238             }
 239         }
 240     }
 241
 242     /* calculate final coupling coordinates, taking into account reusing of
 243        coordinates in successive blocks */
 244     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 245         blk = 0;
 246         while (blk < s->num_blocks) {
 247             int av_uninit(blk1);
 248             AC3Block *block  = &s->blocks[blk];
 249
 250             if (!block->cpl_in_use) {
 251                 blk++;
 252                 continue;
 253             }
 254
 255             for (ch = 1; ch <= s->fbw_channels; ch++) {
 256                 CoefSumType energy_ch, energy_cpl;
 257                 if (!block->channel_in_cpl[ch])
 258                     continue;
 259                 energy_cpl = energy[blk][CPL_CH][bnd];
 260                 energy_ch = energy[blk][ch][bnd];
 261                 blk1 = blk+1;
 262                 while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {
 263                     if (s->blocks[blk1].cpl_in_use) {
 264                         energy_cpl += energy[blk1][CPL_CH][bnd];
 265                         energy_ch += energy[blk1][ch][bnd];
 266                     }
 267                     blk1++;
 268                 }
 269                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
 270             }
 271             blk = blk1;
 272         }
 273     }
 274
 275     /* calculate exponents/mantissas for coupling coordinates */
 276     for (blk = 0; blk < s->num_blocks; blk++) {
 277         AC3Block *block = &s->blocks[blk];
 278         if (!block->cpl_in_use)
 279             continue;
 280
 281 #if CONFIG_AC3ENC_FLOAT
 282         s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
 283                                    cpl_coords[blk][1],
 284                                    s->fbw_channels * 16);
 285 #endif
 286         s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
 287                                     fixed_cpl_coords[blk][1],
 288                                     s->fbw_channels * 16);
 289
 290         for (ch = 1; ch <= s->fbw_channels; ch++) {
 291             int bnd, min_exp, max_exp, master_exp;
 292
 293             if (!block->new_cpl_coords[ch])
 294                 continue;
 295
 296             /* determine master exponent */
 297             min_exp = max_exp = block->cpl_coord_exp[ch][0];
 298             for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
 299                 int exp = block->cpl_coord_exp[ch][bnd];
 300                 min_exp = FFMIN(exp, min_exp);
 301                 max_exp = FFMAX(exp, max_exp);
 302             }
 303             master_exp = ((max_exp - 15) + 2) / 3;
 304             master_exp = FFMAX(master_exp, 0);
 305             while (min_exp < master_exp * 3)
 306                 master_exp--;
 307             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 308                 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
 309                                                         master_exp * 3, 0, 15);
 310             }
 311             block->cpl_master_exp[ch] = master_exp;
 312
 313             /* quantize mantissas */
 314             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 315                 int cpl_exp  = block->cpl_coord_exp[ch][bnd];
 316                 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
 317                 if (cpl_exp == 15)
 318                     cpl_mant >>= 1;
 319                 else
 320                     cpl_mant -= 16;
 321
 322                 block->cpl_coord_mant[ch][bnd] = cpl_mant;
 323             }
 324         }
 325     }
 326
 327     if (CONFIG_EAC3_ENCODER && s->eac3)
 328         ff_eac3_set_cpl_states(s);
 329 }
 330
 331
 332 /*
 333  * Determine rematrixing flags for each block and band.
 334  */
 335 static void compute_rematrixing_strategy(AC3EncodeContext *s)
 336 {
 337     int nb_coefs;
 338     int blk, bnd;
 339     AC3Block *block, *block0;
 340
 341     if (s->channel_mode != AC3_CHMODE_STEREO)
 342         return;
 343
 344     for (blk = 0; blk < s->num_blocks; blk++) {
 345         block = &s->blocks[blk];
 346         block->new_rematrixing_strategy = !blk;
 347
 348         block->num_rematrixing_bands = 4;
 349         if (block->cpl_in_use) {
 350             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
 351             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
 352             if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
 353                 block->new_rematrixing_strategy = 1;
 354         }
 355         nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
 356
 357         if (!s->rematrixing_enabled) {
 358             block0 = block;
 359             continue;
 360         }
 361
 362         for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
 363             /* calculate calculate sum of squared coeffs for one band in one block */
 364             int start = ff_ac3_rematrix_band_tab[bnd];
 365             int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
 366             CoefSumType sum[4];
 367             sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
 368                                  block->mdct_coef[2] + start, end - start);
 369
 370             /* compare sums to determine if rematrixing will be used for this band */
 371             if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
 372                 block->rematrixing_flags[bnd] = 1;
 373             else
 374                 block->rematrixing_flags[bnd] = 0;
 375
 376             /* determine if new rematrixing flags will be sent */
 377             if (blk &&
 378                 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
 379                 block->new_rematrixing_strategy = 1;
 380             }
 381         }
 382         block0 = block;
 383     }
 384 }
 385
 386
 387 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
 388                            const AVFrame *frame, int *got_packet_ptr)
 389 {
 390     AC3EncodeContext *s = avctx->priv_data;
 391     int ret;
 392
 393     if (s->options.allow_per_frame_metadata) {
 394         ret = ff_ac3_validate_metadata(s);
 395         if (ret)
 396             return ret;
 397     }
 398
 399     if (s->bit_alloc.sr_code == 1 || s->eac3)
 400         ff_ac3_adjust_frame_size(s);
 401
 402     copy_input_samples(s, (SampleType **)frame->extended_data);
 403
 404     apply_mdct(s);
 405
 406     if (s->fixed_point)
 407         scale_coefficients(s);
 408
 409     clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
 410                       AC3_MAX_COEFS * s->num_blocks * s->channels);
 411
 412     s->cpl_on = s->cpl_enabled;
 413     ff_ac3_compute_coupling_strategy(s);
 414
 415     if (s->cpl_on)
 416         apply_channel_coupling(s);
 417
 418     compute_rematrixing_strategy(s);
 419
 420     if (!s->fixed_point)
 421         scale_coefficients(s);
 422
 423     ff_ac3_apply_rematrixing(s);
 424
 425     ff_ac3_process_exponents(s);
 426
 427     ret = ff_ac3_compute_bit_allocation(s);
 428     if (ret) {
 429         av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
 430         return ret;
 431     }
 432
 433     ff_ac3_group_exponents(s);
 434
 435     ff_ac3_quantize_mantissas(s);
 436
 437     if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size)))
 438         return ret;
 439     ff_ac3_output_frame(s, avpkt->data);
 440
 441     if (frame->pts != AV_NOPTS_VALUE)
 442         avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);
 443
 444     *got_packet_ptr = 1;
 445     return 0;
 446 }