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