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 34static void scale_coefficients(AC3EncodeContext *s); 35 36static void apply_window(DSPContext *dsp, SampleType *output, 37 const SampleType *input, const SampleType *window, 38 unsigned int len); 39 40static int normalize_samples(AC3EncodeContext *s); 41 42static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len); 43 44static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl); 45 46 47int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s) 48{ 49 int ch; 50 51 FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE * 52 sizeof(*s->windowed_samples), alloc_fail); 53 FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples), 54 alloc_fail); 55 for (ch = 0; ch < s->channels; ch++) { 56 FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch], 57 (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples), 58 alloc_fail); 59 } 60 61 return 0; 62alloc_fail: 63 return AVERROR(ENOMEM); 64} 65 66 67/* 68 * Deinterleave input samples. 69 * Channels are reordered from Libav's default order to AC-3 order. 70 */ 71static void deinterleave_input_samples(AC3EncodeContext *s, 72 const SampleType *samples) 73{ 74 int ch, i; 75 76 /* deinterleave and remap input samples */ 77 for (ch = 0; ch < s->channels; ch++) { 78 const SampleType *sptr; 79 int sinc; 80 81 /* copy last 256 samples of previous frame to the start of the current frame */ 82 memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks], 83 AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0])); 84 85 /* deinterleave */ 86 sinc = s->channels; 87 sptr = samples + s->channel_map[ch]; 88 for (i = AC3_BLOCK_SIZE; i < AC3_BLOCK_SIZE * (s->num_blocks + 1); i++) { 89 s->planar_samples[ch][i] = *sptr; 90 sptr += sinc; 91 } 92 } 93} 94 95 96/* 97 * Apply the MDCT to input samples to generate frequency coefficients. 98 * This applies the KBD window and normalizes the input to reduce precision 99 * loss due to fixed-point calculations. 100 */ 101static void apply_mdct(AC3EncodeContext *s) 102{ 103 int blk, ch; 104 105 for (ch = 0; ch < s->channels; ch++) { 106 for (blk = 0; blk < s->num_blocks; blk++) { 107 AC3Block *block = &s->blocks[blk]; 108 const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE]; 109 110 apply_window(&s->dsp, s->windowed_samples, input_samples, 111 s->mdct_window, AC3_WINDOW_SIZE); 112 113 if (s->fixed_point) 114 block->coeff_shift[ch+1] = normalize_samples(s); 115 116 s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1], 117 s->windowed_samples); 118 } 119 } 120} 121 122 123/* 124 * Calculate coupling channel and coupling coordinates. 125 */ 126static void apply_channel_coupling(AC3EncodeContext *s) 127{ 128 LOCAL_ALIGNED_16(CoefType, cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]); 129#if CONFIG_AC3ENC_FLOAT 130 LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]); 131#else 132 int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords; 133#endif 134 int blk, ch, bnd, i, j; 135 CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}}; 136 int cpl_start, num_cpl_coefs; 137 138 memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords)); 139#if CONFIG_AC3ENC_FLOAT 140 memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords)); 141#endif 142 143 /* align start to 16-byte boundary. align length to multiple of 32. 144 note: coupling start bin % 4 will always be 1 */ 145 cpl_start = s->start_freq[CPL_CH] - 1; 146 num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32); 147 cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs; 148 149 /* calculate coupling channel from fbw channels */ 150 for (blk = 0; blk < s->num_blocks; blk++) { 151 AC3Block *block = &s->blocks[blk]; 152 CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start]; 153 if (!block->cpl_in_use) 154 continue; 155 memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef)); 156 for (ch = 1; ch <= s->fbw_channels; ch++) { 157 CoefType *ch_coef = &block->mdct_coef[ch][cpl_start]; 158 if (!block->channel_in_cpl[ch]) 159 continue; 160 for (i = 0; i < num_cpl_coefs; i++) 161 cpl_coef[i] += ch_coef[i]; 162 } 163 164 /* coefficients must be clipped in order to be encoded */ 165 clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs); 166 } 167 168 /* calculate energy in each band in coupling channel and each fbw channel */ 169 /* TODO: possibly use SIMD to speed up energy calculation */ 170 bnd = 0; 171 i = s->start_freq[CPL_CH]; 172 while (i < s->cpl_end_freq) { 173 int band_size = s->cpl_band_sizes[bnd]; 174 for (ch = CPL_CH; ch <= s->fbw_channels; ch++) { 175 for (blk = 0; blk < s->num_blocks; blk++) { 176 AC3Block *block = &s->blocks[blk]; 177 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch])) 178 continue; 179 for (j = 0; j < band_size; j++) { 180 CoefType v = block->mdct_coef[ch][i+j]; 181 MAC_COEF(energy[blk][ch][bnd], v, v); 182 } 183 } 184 } 185 i += band_size; 186 bnd++; 187 } 188 189 /* calculate coupling coordinates for all blocks for all channels */ 190 for (blk = 0; blk < s->num_blocks; blk++) { 191 AC3Block *block = &s->blocks[blk]; 192 if (!block->cpl_in_use) 193 continue; 194 for (ch = 1; ch <= s->fbw_channels; ch++) { 195 if (!block->channel_in_cpl[ch]) 196 continue; 197 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { 198 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd], 199 energy[blk][CPL_CH][bnd]); 200 } 201 } 202 } 203 204 /* determine which blocks to send new coupling coordinates for */ 205 for (blk = 0; blk < s->num_blocks; blk++) { 206 AC3Block *block = &s->blocks[blk]; 207 AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL; 208 209 memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords)); 210 211 if (block->cpl_in_use) { 212 /* send new coordinates if this is the first block, if previous 213 * block did not use coupling but this block does, the channels 214 * using coupling has changed from the previous block, or the 215 * coordinate difference from the last block for any channel is 216 * greater than a threshold value. */ 217 if (blk == 0 || !block0->cpl_in_use) { 218 for (ch = 1; ch <= s->fbw_channels; ch++) 219 block->new_cpl_coords[ch] = 1; 220 } else { 221 for (ch = 1; ch <= s->fbw_channels; ch++) { 222 if (!block->channel_in_cpl[ch]) 223 continue; 224 if (!block0->channel_in_cpl[ch]) { 225 block->new_cpl_coords[ch] = 1; 226 } else { 227 CoefSumType coord_diff = 0; 228 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { 229 coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] - 230 cpl_coords[blk ][ch][bnd]); 231 } 232 coord_diff /= s->num_cpl_bands; 233 if (coord_diff > NEW_CPL_COORD_THRESHOLD) 234 block->new_cpl_coords[ch] = 1; 235 } 236 } 237 } 238 } 239 } 240 241 /* calculate final coupling coordinates, taking into account reusing of 242 coordinates in successive blocks */ 243 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { 244 blk = 0; 245 while (blk < s->num_blocks) { 246 int av_uninit(blk1); 247 AC3Block *block = &s->blocks[blk]; 248 249 if (!block->cpl_in_use) { 250 blk++; 251 continue; 252 } 253 254 for (ch = 1; ch <= s->fbw_channels; ch++) { 255 CoefSumType energy_ch, energy_cpl; 256 if (!block->channel_in_cpl[ch]) 257 continue; 258 energy_cpl = energy[blk][CPL_CH][bnd]; 259 energy_ch = energy[blk][ch][bnd]; 260 blk1 = blk+1; 261 while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) { 262 if (s->blocks[blk1].cpl_in_use) { 263 energy_cpl += energy[blk1][CPL_CH][bnd]; 264 energy_ch += energy[blk1][ch][bnd]; 265 } 266 blk1++; 267 } 268 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl); 269 } 270 blk = blk1; 271 } 272 } 273 274 /* calculate exponents/mantissas for coupling coordinates */ 275 for (blk = 0; blk < s->num_blocks; blk++) { 276 AC3Block *block = &s->blocks[blk]; 277 if (!block->cpl_in_use) 278 continue; 279 280#if CONFIG_AC3ENC_FLOAT 281 s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1], 282 cpl_coords[blk][1], 283 s->fbw_channels * 16); 284#endif 285 s->ac3dsp.extract_exponents(block->cpl_coord_exp[1], 286 fixed_cpl_coords[blk][1], 287 s->fbw_channels * 16); 288 289 for (ch = 1; ch <= s->fbw_channels; ch++) { 290 int bnd, min_exp, max_exp, master_exp; 291 292 if (!block->new_cpl_coords[ch]) 293 continue; 294 295 /* determine master exponent */ 296 min_exp = max_exp = block->cpl_coord_exp[ch][0]; 297 for (bnd = 1; bnd < s->num_cpl_bands; bnd++) { 298 int exp = block->cpl_coord_exp[ch][bnd]; 299 min_exp = FFMIN(exp, min_exp); 300 max_exp = FFMAX(exp, max_exp); 301 } 302 master_exp = ((max_exp - 15) + 2) / 3; 303 master_exp = FFMAX(master_exp, 0); 304 while (min_exp < master_exp * 3) 305 master_exp--; 306 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { 307 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] - 308 master_exp * 3, 0, 15); 309 } 310 block->cpl_master_exp[ch] = master_exp; 311 312 /* quantize mantissas */ 313 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { 314 int cpl_exp = block->cpl_coord_exp[ch][bnd]; 315 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24; 316 if (cpl_exp == 15) 317 cpl_mant >>= 1; 318 else 319 cpl_mant -= 16; 320 321 block->cpl_coord_mant[ch][bnd] = cpl_mant; 322 } 323 } 324 } 325 326 if (CONFIG_EAC3_ENCODER && s->eac3) 327 ff_eac3_set_cpl_states(s); 328} 329 330 331/* 332 * Determine rematrixing flags for each block and band. 333 */ 334static void compute_rematrixing_strategy(AC3EncodeContext *s) 335{ 336 int nb_coefs; 337 int blk, bnd, i; 338 AC3Block *block, *av_uninit(block0); 339 340 if (s->channel_mode != AC3_CHMODE_STEREO) 341 return; 342 343 for (blk = 0; blk < s->num_blocks; blk++) { 344 block = &s->blocks[blk]; 345 block->new_rematrixing_strategy = !blk; 346 347 block->num_rematrixing_bands = 4; 348 if (block->cpl_in_use) { 349 block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61); 350 block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37); 351 if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands) 352 block->new_rematrixing_strategy = 1; 353 } 354 nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]); 355 356 if (!s->rematrixing_enabled) { 357 block0 = block; 358 continue; 359 } 360 361 for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) { 362 /* calculate calculate sum of squared coeffs for one band in one block */ 363 int start = ff_ac3_rematrix_band_tab[bnd]; 364 int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]); 365 CoefSumType sum[4] = {0,}; 366 for (i = start; i < end; i++) { 367 CoefType lt = block->mdct_coef[1][i]; 368 CoefType rt = block->mdct_coef[2][i]; 369 CoefType md = lt + rt; 370 CoefType sd = lt - rt; 371 MAC_COEF(sum[0], lt, lt); 372 MAC_COEF(sum[1], rt, rt); 373 MAC_COEF(sum[2], md, md); 374 MAC_COEF(sum[3], sd, sd); 375 } 376 377 /* compare sums to determine if rematrixing will be used for this band */ 378 if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1])) 379 block->rematrixing_flags[bnd] = 1; 380 else 381 block->rematrixing_flags[bnd] = 0; 382 383 /* determine if new rematrixing flags will be sent */ 384 if (blk && 385 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) { 386 block->new_rematrixing_strategy = 1; 387 } 388 } 389 block0 = block; 390 } 391} 392 393 394int AC3_NAME(encode_frame)(AVCodecContext *avctx, unsigned char *frame, 395 int buf_size, void *data) 396{ 397 AC3EncodeContext *s = avctx->priv_data; 398 const SampleType *samples = data; 399 int ret; 400 401 if (s->options.allow_per_frame_metadata) { 402 ret = ff_ac3_validate_metadata(s); 403 if (ret) 404 return ret; 405 } 406 407 if (s->bit_alloc.sr_code == 1 || s->eac3) 408 ff_ac3_adjust_frame_size(s); 409 410 deinterleave_input_samples(s, samples); 411 412 apply_mdct(s); 413 414 if (s->fixed_point) 415 scale_coefficients(s); 416 417 clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1], 418 AC3_MAX_COEFS * s->num_blocks * s->channels); 419 420 s->cpl_on = s->cpl_enabled; 421 ff_ac3_compute_coupling_strategy(s); 422 423 if (s->cpl_on) 424 apply_channel_coupling(s); 425 426 compute_rematrixing_strategy(s); 427 428 if (!s->fixed_point) 429 scale_coefficients(s); 430 431 ff_ac3_apply_rematrixing(s); 432 433 ff_ac3_process_exponents(s); 434 435 ret = ff_ac3_compute_bit_allocation(s); 436 if (ret) { 437 av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n"); 438 return ret; 439 } 440 441 ff_ac3_group_exponents(s); 442 443 ff_ac3_quantize_mantissas(s); 444 445 ff_ac3_output_frame(s, frame); 446 447 return s->frame_size; 448} 449