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