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 "config_components.h"
  30
  31 #include <stdint.h>
  32
  33 #include "libavutil/attributes.h"
  34 #include "libavutil/internal.h"
  35 #include "libavutil/mem_internal.h"
  36
  37 #include "audiodsp.h"
  38 #include "ac3enc.h"
  39 #include "eac3enc.h"
  40
  41
  42 static int allocate_sample_buffers(AC3EncodeContext *s)
  43 {
  44     int ch;
  45
  46     if (!FF_ALLOC_TYPED_ARRAY(s->windowed_samples, AC3_WINDOW_SIZE) ||
  47         !FF_ALLOCZ_TYPED_ARRAY(s->planar_samples,  s->channels))
  48         return AVERROR(ENOMEM);
  49
  50     for (ch = 0; ch < s->channels; ch++) {
  51         if (!(s->planar_samples[ch] = av_mallocz((AC3_FRAME_SIZE + AC3_BLOCK_SIZE) *
  52                                                   sizeof(**s->planar_samples))))
  53             return AVERROR(ENOMEM);
  54     }
  55     return 0;
  56 }
  57
  58
  59 /*
  60  * Copy input samples.
  61  * Channels are reordered from FFmpeg's default order to AC-3 order.
  62  */
  63 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
  64 {
  65     int ch;
  66
  67     /* copy and remap input samples */
  68     for (ch = 0; ch < s->channels; ch++) {
  69         /* copy last 256 samples of previous frame to the start of the current frame */
  70         memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
  71                AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
  72
  73         /* copy new samples for current frame */
  74         memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
  75                samples[s->channel_map[ch]],
  76                AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
  77     }
  78 }
  79
  80
  81 /*
  82  * Apply the MDCT to input samples to generate frequency coefficients.
  83  * This applies the KBD window and normalizes the input to reduce precision
  84  * loss due to fixed-point calculations.
  85  */
  86 static void apply_mdct(AC3EncodeContext *s)
  87 {
  88     int blk, ch;
  89
  90     for (ch = 0; ch < s->channels; ch++) {
  91         for (blk = 0; blk < s->num_blocks; blk++) {
  92             AC3Block *block = &s->blocks[blk];
  93             const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
  94
  95             s->fdsp->vector_fmul(s->windowed_samples, input_samples,
  96                                  s->mdct_window, AC3_BLOCK_SIZE);
  97             s->fdsp->vector_fmul_reverse(s->windowed_samples + AC3_BLOCK_SIZE,
  98                                          &input_samples[AC3_BLOCK_SIZE],
  99                                          s->mdct_window, AC3_BLOCK_SIZE);
 100
 101             s->tx_fn(s->tx, block->mdct_coef[ch+1],
 102                      s->windowed_samples, sizeof(float));
 103         }
 104     }
 105 }
 106
 107
 108 /*
 109  * Calculate coupling channel and coupling coordinates.
 110  */
 111 static void apply_channel_coupling(AC3EncodeContext *s)
 112 {
 113     LOCAL_ALIGNED_16(CoefType, cpl_coords,      [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 114 #if AC3ENC_FLOAT
 115     LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
 116 #else
 117     int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
 118 #endif
 119     int av_uninit(blk), ch, bnd, i, j;
 120     CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
 121     int cpl_start, num_cpl_coefs;
 122
 123     memset(cpl_coords,       0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 124 #if AC3ENC_FLOAT
 125     memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
 126 #endif
 127
 128     /* align start to 16-byte boundary. align length to multiple of 32.
 129         note: coupling start bin % 4 will always be 1 */
 130     cpl_start     = s->start_freq[CPL_CH] - 1;
 131     num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
 132     cpl_start     = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
 133
 134     /* calculate coupling channel from fbw channels */
 135     for (blk = 0; blk < s->num_blocks; blk++) {
 136         AC3Block *block = &s->blocks[blk];
 137         CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
 138         if (!block->cpl_in_use)
 139             continue;
 140         memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
 141         for (ch = 1; ch <= s->fbw_channels; ch++) {
 142             CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
 143             if (!block->channel_in_cpl[ch])
 144                 continue;
 145             for (i = 0; i < num_cpl_coefs; i++)
 146                 cpl_coef[i] += ch_coef[i];
 147         }
 148
 149         /* coefficients must be clipped in order to be encoded */
 150         clip_coefficients(&s->adsp, cpl_coef, num_cpl_coefs);
 151     }
 152
 153     /* calculate energy in each band in coupling channel and each fbw channel */
 154     /* TODO: possibly use SIMD to speed up energy calculation */
 155     bnd = 0;
 156     i = s->start_freq[CPL_CH];
 157     while (i < s->cpl_end_freq) {
 158         int band_size = s->cpl_band_sizes[bnd];
 159         for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
 160             for (blk = 0; blk < s->num_blocks; blk++) {
 161                 AC3Block *block = &s->blocks[blk];
 162                 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
 163                     continue;
 164                 for (j = 0; j < band_size; j++) {
 165                     CoefType v = block->mdct_coef[ch][i+j];
 166                     MAC_COEF(energy[blk][ch][bnd], v, v);
 167                 }
 168             }
 169         }
 170         i += band_size;
 171         bnd++;
 172     }
 173
 174     /* calculate coupling coordinates for all blocks for all channels */
 175     for (blk = 0; blk < s->num_blocks; blk++) {
 176         AC3Block *block  = &s->blocks[blk];
 177         if (!block->cpl_in_use)
 178             continue;
 179         for (ch = 1; ch <= s->fbw_channels; ch++) {
 180             if (!block->channel_in_cpl[ch])
 181                 continue;
 182             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 183                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
 184                                                           energy[blk][CPL_CH][bnd]);
 185             }
 186         }
 187     }
 188
 189     /* determine which blocks to send new coupling coordinates for */
 190     for (blk = 0; blk < s->num_blocks; blk++) {
 191         AC3Block *block  = &s->blocks[blk];
 192         AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
 193
 194         memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
 195
 196         if (block->cpl_in_use) {
 197             /* send new coordinates if this is the first block, if previous
 198              * block did not use coupling but this block does, the channels
 199              * using coupling has changed from the previous block, or the
 200              * coordinate difference from the last block for any channel is
 201              * greater than a threshold value. */
 202             if (blk == 0 || !block0->cpl_in_use) {
 203                 for (ch = 1; ch <= s->fbw_channels; ch++)
 204                     block->new_cpl_coords[ch] = 1;
 205             } else {
 206                 for (ch = 1; ch <= s->fbw_channels; ch++) {
 207                     if (!block->channel_in_cpl[ch])
 208                         continue;
 209                     if (!block0->channel_in_cpl[ch]) {
 210                         block->new_cpl_coords[ch] = 1;
 211                     } else {
 212                         CoefSumType coord_diff = 0;
 213                         for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 214                             coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
 215                                                 cpl_coords[blk  ][ch][bnd]);
 216                         }
 217                         coord_diff /= s->num_cpl_bands;
 218                         if (coord_diff > NEW_CPL_COORD_THRESHOLD)
 219                             block->new_cpl_coords[ch] = 1;
 220                     }
 221                 }
 222             }
 223         }
 224     }
 225
 226     /* calculate final coupling coordinates, taking into account reusing of
 227        coordinates in successive blocks */
 228     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 229         blk = 0;
 230         while (blk < s->num_blocks) {
 231             int av_uninit(blk1);
 232             AC3Block *block  = &s->blocks[blk];
 233
 234             if (!block->cpl_in_use) {
 235                 blk++;
 236                 continue;
 237             }
 238
 239             for (ch = 1; ch <= s->fbw_channels; ch++) {
 240                 CoefSumType energy_ch, energy_cpl;
 241                 if (!block->channel_in_cpl[ch])
 242                     continue;
 243                 energy_cpl = energy[blk][CPL_CH][bnd];
 244                 energy_ch = energy[blk][ch][bnd];
 245                 blk1 = blk+1;
 246                 while (blk1 < s->num_blocks && !s->blocks[blk1].new_cpl_coords[ch]) {
 247                     if (s->blocks[blk1].cpl_in_use) {
 248                         energy_cpl += energy[blk1][CPL_CH][bnd];
 249                         energy_ch += energy[blk1][ch][bnd];
 250                     }
 251                     blk1++;
 252                 }
 253                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
 254             }
 255             blk = blk1;
 256         }
 257     }
 258
 259     /* calculate exponents/mantissas for coupling coordinates */
 260     for (blk = 0; blk < s->num_blocks; blk++) {
 261         AC3Block *block = &s->blocks[blk];
 262         if (!block->cpl_in_use)
 263             continue;
 264
 265 #if AC3ENC_FLOAT
 266         s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
 267                                    cpl_coords[blk][1],
 268                                    s->fbw_channels * 16);
 269 #endif
 270         s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
 271                                     fixed_cpl_coords[blk][1],
 272                                     s->fbw_channels * 16);
 273
 274         for (ch = 1; ch <= s->fbw_channels; ch++) {
 275             int bnd, min_exp, max_exp, master_exp;
 276
 277             if (!block->new_cpl_coords[ch])
 278                 continue;
 279
 280             /* determine master exponent */
 281             min_exp = max_exp = block->cpl_coord_exp[ch][0];
 282             for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
 283                 int exp = block->cpl_coord_exp[ch][bnd];
 284                 min_exp = FFMIN(exp, min_exp);
 285                 max_exp = FFMAX(exp, max_exp);
 286             }
 287             master_exp = ((max_exp - 15) + 2) / 3;
 288             master_exp = FFMAX(master_exp, 0);
 289             while (min_exp < master_exp * 3)
 290                 master_exp--;
 291             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 292                 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
 293                                                         master_exp * 3, 0, 15);
 294             }
 295             block->cpl_master_exp[ch] = master_exp;
 296
 297             /* quantize mantissas */
 298             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
 299                 int cpl_exp  = block->cpl_coord_exp[ch][bnd];
 300                 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
 301                 if (cpl_exp == 15)
 302                     cpl_mant >>= 1;
 303                 else
 304                     cpl_mant -= 16;
 305
 306                 block->cpl_coord_mant[ch][bnd] = cpl_mant;
 307             }
 308         }
 309     }
 310
 311     if (AC3ENC_FLOAT && CONFIG_EAC3_ENCODER && s->eac3)
 312         ff_eac3_set_cpl_states(s);
 313 }
 314
 315
 316 /*
 317  * Determine rematrixing flags for each block and band.
 318  */
 319 static void compute_rematrixing_strategy(AC3EncodeContext *s)
 320 {
 321     int nb_coefs;
 322     int blk, bnd;
 323     AC3Block *block, *block0 = NULL;
 324
 325     if (s->channel_mode != AC3_CHMODE_STEREO)
 326         return;
 327
 328     for (blk = 0; blk < s->num_blocks; blk++) {
 329         block = &s->blocks[blk];
 330         block->new_rematrixing_strategy = !blk;
 331
 332         block->num_rematrixing_bands = 4;
 333         if (block->cpl_in_use) {
 334             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
 335             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
 336             if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
 337                 block->new_rematrixing_strategy = 1;
 338         }
 339         nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
 340
 341         if (!s->rematrixing_enabled) {
 342             block0 = block;
 343             continue;
 344         }
 345
 346         for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
 347             /* calculate sum of squared coeffs for one band in one block */
 348             int start = ff_ac3_rematrix_band_tab[bnd];
 349             int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
 350             CoefSumType sum[4];
 351             sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
 352                                  block->mdct_coef[2] + start, end - start);
 353
 354             /* compare sums to determine if rematrixing will be used for this band */
 355             if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
 356                 block->rematrixing_flags[bnd] = 1;
 357             else
 358                 block->rematrixing_flags[bnd] = 0;
 359
 360             /* determine if new rematrixing flags will be sent */
 361             if (blk &&
 362                 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
 363                 block->new_rematrixing_strategy = 1;
 364             }
 365         }
 366         block0 = block;
 367     }
 368 }
 369
 370
 371 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
 372                            const AVFrame *frame, int *got_packet_ptr)
 373 {
 374     AC3EncodeContext *s = avctx->priv_data;
 375     int ret;
 376
 377     if (s->options.allow_per_frame_metadata) {
 378         ret = ff_ac3_validate_metadata(s);
 379         if (ret)
 380             return ret;
 381     }
 382
 383     if (s->bit_alloc.sr_code == 1 || (AC3ENC_FLOAT && s->eac3))
 384         ff_ac3_adjust_frame_size(s);
 385
 386     copy_input_samples(s, (SampleType **)frame->extended_data);
 387
 388     apply_mdct(s);
 389
 390     s->cpl_on = s->cpl_enabled;
 391     ff_ac3_compute_coupling_strategy(s);
 392
 393     if (s->cpl_on)
 394         apply_channel_coupling(s);
 395
 396     compute_rematrixing_strategy(s);
 397
 398 #if AC3ENC_FLOAT
 399     scale_coefficients(s);
 400 #endif
 401
 402     return ff_ac3_encode_frame_common_end(avctx, avpkt, frame, got_packet_ptr);
 403 }