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