FFmpeg: libavcodec/ac3enc_template.c Source File

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libavcodec

ac3enc_template.c

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1 /*

2 * AC-3 encoder float/fixed template

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 */

24 /**

25 * @file

26 * AC-3 encoder float/fixed template

27 */

29 #include <stdint.h>

31 #include "libavutil/internal.h"

33 /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */

35 static void scale_coefficients(AC3EncodeContext *s);

37 static void apply_window(void *dsp, SampleType *output,

38 const SampleType *input, const SampleType *window,

39 unsigned int len);

41 static int normalize_samples(AC3EncodeContext *s);

43 static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len);

45 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl);

47 static void sum_square_butterfly(AC3EncodeContext *s, CoefSumType sum[4],

48 const CoefType *coef0, const CoefType *coef1,

49 int len);

51 int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)

52 {

53 int ch;

55 FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *

56 sizeof(*s->windowed_samples), alloc_fail);

57 FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),

58 alloc_fail);

59 for (ch = 0; ch < s->channels; ch++) {

60 FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],

61 (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),

62 alloc_fail);

63 }

65 return 0;

66 alloc_fail:

67 return AVERROR(ENOMEM);

68 }

71 /*

72 * Copy input samples.

73 * Channels are reordered from FFmpeg's default order to AC-3 order.

74 */

75 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)

76 {

77 int ch;

79 /* copy and remap input samples */

80 for (ch = 0; ch < s->channels; ch++) {

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]));

85 /* copy new samples for current frame */

86 memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],

87 samples[s->channel_map[ch]],

88 AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));

89 }

90 }

93 /*

94 * Apply the MDCT to input samples to generate frequency coefficients.

95 * This applies the KBD window and normalizes the input to reduce precision

96 * loss due to fixed-point calculations.

97 */

98 static void apply_mdct(AC3EncodeContext *s)

99 {

100 int blk, ch;

101

102 for (ch = 0; ch < s->channels; ch++) {

103 for (blk = 0; blk < s->num_blocks; blk++) {

104 AC3Block *block = &s->blocks[blk];

105 const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];

106

107 #if CONFIG_AC3ENC_FLOAT

108 apply_window(&s->fdsp, s->windowed_samples, input_samples,

109 s->mdct_window, AC3_WINDOW_SIZE);

110 #else

111 apply_window(&s->dsp, s->windowed_samples, input_samples,

112 s->mdct_window, AC3_WINDOW_SIZE);

113 #endif

114

115 if (s->fixed_point)

116 block->coeff_shift[ch+1] = normalize_samples(s);

117

118 s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],

119 s->windowed_samples);

120 }

121 }

122 }

123

124

125 /*

126 * Calculate coupling channel and coupling coordinates.

127 */

128 static void apply_channel_coupling(AC3EncodeContext *s)

129 {

130 LOCAL_ALIGNED_16(CoefType, cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);

131 #if CONFIG_AC3ENC_FLOAT

132 LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);

133 #else

134 int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;

135 #endif

136 int av_uninit(blk), ch, bnd, i, j;

137 CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};

138 int cpl_start, num_cpl_coefs;

139

140 memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));

141 #if CONFIG_AC3ENC_FLOAT

142 memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));

143 #endif

144

145 /* align start to 16-byte boundary. align length to multiple of 32.

146 note: coupling start bin % 4 will always be 1 */

147 cpl_start = s->start_freq[CPL_CH] - 1;

148 num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);

149 cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;

150

151 /* calculate coupling channel from fbw channels */

152 for (blk = 0; blk < s->num_blocks; blk++) {

153 AC3Block *block = &s->blocks[blk];

154 CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];

155 if (!block->cpl_in_use)

156 continue;

157 memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));

158 for (ch = 1; ch <= s->fbw_channels; ch++) {

159 CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];

160 if (!block->channel_in_cpl[ch])

161 continue;

162 for (i = 0; i < num_cpl_coefs; i++)

163 cpl_coef[i] += ch_coef[i];

164 }

165

166 /* coefficients must be clipped in order to be encoded */

167 clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);

168 }

169

170 /* calculate energy in each band in coupling channel and each fbw channel */

171 /* TODO: possibly use SIMD to speed up energy calculation */

172 bnd = 0;

173 i = s->start_freq[CPL_CH];

174 while (i < s->cpl_end_freq) {

175 int band_size = s->cpl_band_sizes[bnd];

176 for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {

177 for (blk = 0; blk < s->num_blocks; blk++) {

178 AC3Block *block = &s->blocks[blk];

179 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))

180 continue;

181 for (j = 0; j < band_size; j++) {

182 CoefType v = block->mdct_coef[ch][i+j];

183 MAC_COEF(energy[blk][ch][bnd], v, v);

184 }

185 }

186 }

187 i += band_size;

188 bnd++;

189 }

190

191 /* calculate coupling coordinates for all blocks for all channels */

192 for (blk = 0; blk < s->num_blocks; blk++) {

193 AC3Block *block = &s->blocks[blk];

194 if (!block->cpl_in_use)

195 continue;

196 for (ch = 1; ch <= s->fbw_channels; ch++) {

197 if (!block->channel_in_cpl[ch])

198 continue;

199 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {

200 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],

201 energy[blk][CPL_CH][bnd]);

202 }

203 }

204 }

205

206 /* determine which blocks to send new coupling coordinates for */

207 for (blk = 0; blk < s->num_blocks; blk++) {

208 AC3Block *block = &s->blocks[blk];

209 AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;

210

211 memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));

212

213 if (block->cpl_in_use) {

214 /* send new coordinates if this is the first block, if previous

215 * block did not use coupling but this block does, the channels

216 * using coupling has changed from the previous block, or the

217 * coordinate difference from the last block for any channel is

218 * greater than a threshold value. */

219 if (blk == 0 || !block0->cpl_in_use) {

220 for (ch = 1; ch <= s->fbw_channels; ch++)

221 block->new_cpl_coords[ch] = 1;

222 } else {

223 for (ch = 1; ch <= s->fbw_channels; ch++) {

224 if (!block->channel_in_cpl[ch])

225 continue;

226 if (!block0->channel_in_cpl[ch]) {

227 block->new_cpl_coords[ch] = 1;

228 } else {

229 CoefSumType coord_diff = 0;

230 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {

231 coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -

232 cpl_coords[blk ][ch][bnd]);

233 }

234 coord_diff /= s->num_cpl_bands;

235 if (coord_diff > NEW_CPL_COORD_THRESHOLD)

236 block->new_cpl_coords[ch] = 1;

237 }

238 }

239 }

240 }

241 }

242

243 /* calculate final coupling coordinates, taking into account reusing of

244 coordinates in successive blocks */

245 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {

246 blk = 0;

247 while (blk < s->num_blocks) {

248 int av_uninit(blk1);

249 AC3Block *block = &s->blocks[blk];

250

251 if (!block->cpl_in_use) {

252 blk++;

253 continue;

254 }

255

256 for (ch = 1; ch <= s->fbw_channels; ch++) {

257 CoefSumType energy_ch, energy_cpl;

258 if (!block->channel_in_cpl[ch])

259 continue;

260 energy_cpl = energy[blk][CPL_CH][bnd];

261 energy_ch = energy[blk][ch][bnd];

262 blk1 = blk+1;

263 while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) {

264 if (s->blocks[blk1].cpl_in_use) {

265 energy_cpl += energy[blk1][CPL_CH][bnd];

266 energy_ch += energy[blk1][ch][bnd];

267 }

268 blk1++;

269 }

270 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);

271 }

272 blk = blk1;

273 }

274 }

275

276 /* calculate exponents/mantissas for coupling coordinates */

277 for (blk = 0; blk < s->num_blocks; blk++) {

278 AC3Block *block = &s->blocks[blk];

279 if (!block->cpl_in_use)

280 continue;

281

282 #if CONFIG_AC3ENC_FLOAT

283 s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],

284 cpl_coords[blk][1],

285 s->fbw_channels * 16);

286 #endif

287 s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],

288 fixed_cpl_coords[blk][1],

289 s->fbw_channels * 16);

290

291 for (ch = 1; ch <= s->fbw_channels; ch++) {

292 int bnd, min_exp, max_exp, master_exp;

293

294 if (!block->new_cpl_coords[ch])

295 continue;

296

297 /* determine master exponent */

298 min_exp = max_exp = block->cpl_coord_exp[ch][0];

299 for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {

300 int exp = block->cpl_coord_exp[ch][bnd];

301 min_exp = FFMIN(exp, min_exp);

302 max_exp = FFMAX(exp, max_exp);

303 }

304 master_exp = ((max_exp - 15) + 2) / 3;

305 master_exp = FFMAX(master_exp, 0);

306 while (min_exp < master_exp * 3)

307 master_exp--;

308 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {

309 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -

310 master_exp * 3, 0, 15);

311 }

312 block->cpl_master_exp[ch] = master_exp;

313

314 /* quantize mantissas */

315 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {

316 int cpl_exp = block->cpl_coord_exp[ch][bnd];

317 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;

318 if (cpl_exp == 15)

319 cpl_mant >>= 1;

320 else

321 cpl_mant -= 16;

322

323 block->cpl_coord_mant[ch][bnd] = cpl_mant;

324 }

325 }

326 }

327

328 if (CONFIG_EAC3_ENCODER && s->eac3)

329 ff_eac3_set_cpl_states(s);

330 }

331

332

333 /*

334 * Determine rematrixing flags for each block and band.

335 */

336 static void compute_rematrixing_strategy(AC3EncodeContext *s)

337 {

338 int nb_coefs;

339 int blk, bnd;

340 AC3Block *block, *block0 = NULL;

341

342 if (s->channel_mode != AC3_CHMODE_STEREO)

343 return;

344

345 for (blk = 0; blk < s->num_blocks; blk++) {

346 block = &s->blocks[blk];

347 block->new_rematrixing_strategy = !blk;

348

349 block->num_rematrixing_bands = 4;

350 if (block->cpl_in_use) {

351 block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);

352 block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);

353 if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)

354 block->new_rematrixing_strategy = 1;

355 }

356 nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);

357

358 if (!s->rematrixing_enabled) {

359 block0 = block;

360 continue;

361 }

362

363 for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {

364 /* calculate sum of squared coeffs for one band in one block */

365 int start = ff_ac3_rematrix_band_tab[bnd];

366 int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);

367 CoefSumType sum[4];

368 sum_square_butterfly(s, sum, block->mdct_coef[1] + start,

369 block->mdct_coef[2] + start, end - start);

370

371 /* compare sums to determine if rematrixing will be used for this band */

372 if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))

373 block->rematrixing_flags[bnd] = 1;

374 else

375 block->rematrixing_flags[bnd] = 0;

376

377 /* determine if new rematrixing flags will be sent */

378 if (blk &&

379 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {

380 block->new_rematrixing_strategy = 1;

381 }

382 }

383 block0 = block;

384 }

385 }

386

387

388 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,

389 const AVFrame *frame, int *got_packet_ptr)

390 {

391 AC3EncodeContext *s = avctx->priv_data;

392 int ret;

393

394 if (s->options.allow_per_frame_metadata) {

395 ret = ff_ac3_validate_metadata(s);

396 if (ret)

397 return ret;

398 }

399

400 if (s->bit_alloc.sr_code == 1 || s->eac3)

401 ff_ac3_adjust_frame_size(s);

402

403 copy_input_samples(s, (SampleType **)frame->extended_data);

404

405 apply_mdct(s);

406

407 if (s->fixed_point)

408 scale_coefficients(s);

409

410 clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],

411 AC3_MAX_COEFS * s->num_blocks * s->channels);

412

413 s->cpl_on = s->cpl_enabled;

414 ff_ac3_compute_coupling_strategy(s);

415

416 if (s->cpl_on)

417 apply_channel_coupling(s);

418

419 compute_rematrixing_strategy(s);

420

421 if (!s->fixed_point)

422 scale_coefficients(s);

423

424 ff_ac3_apply_rematrixing(s);

425

426 ff_ac3_process_exponents(s);

427

428 ret = ff_ac3_compute_bit_allocation(s);

429 if (ret) {

430 av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");

431 return ret;

432 }

433

434 ff_ac3_group_exponents(s);

435

436 ff_ac3_quantize_mantissas(s);

437

438 if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size)) < 0)

439 return ret;

440 ff_ac3_output_frame(s, avpkt->data);

441

442 if (frame->pts != AV_NOPTS_VALUE)

443 avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->delay);

444

445 *got_packet_ptr = 1;

446 return 0;

447 }

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