| 1 | /* |
| 2 | * ALAC audio encoder |
| 3 | * Copyright (c) 2008 Jaikrishnan Menon <realityman@gmx.net> |
| 4 | * |
| 5 | * This file is part of FFmpeg. |
| 6 | * |
| 7 | * FFmpeg is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * FFmpeg is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with FFmpeg; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | #include "avcodec.h" |
| 23 | #include "put_bits.h" |
| 24 | #include "internal.h" |
| 25 | #include "lpc.h" |
| 26 | #include "mathops.h" |
| 27 | #include "alac_data.h" |
| 28 | |
| 29 | #define DEFAULT_FRAME_SIZE 4096 |
| 30 | #define ALAC_EXTRADATA_SIZE 36 |
| 31 | #define ALAC_FRAME_HEADER_SIZE 55 |
| 32 | #define ALAC_FRAME_FOOTER_SIZE 3 |
| 33 | |
| 34 | #define ALAC_ESCAPE_CODE 0x1FF |
| 35 | #define ALAC_MAX_LPC_ORDER 30 |
| 36 | #define DEFAULT_MAX_PRED_ORDER 6 |
| 37 | #define DEFAULT_MIN_PRED_ORDER 4 |
| 38 | #define ALAC_MAX_LPC_PRECISION 9 |
| 39 | #define ALAC_MAX_LPC_SHIFT 9 |
| 40 | |
| 41 | #define ALAC_CHMODE_LEFT_RIGHT 0 |
| 42 | #define ALAC_CHMODE_LEFT_SIDE 1 |
| 43 | #define ALAC_CHMODE_RIGHT_SIDE 2 |
| 44 | #define ALAC_CHMODE_MID_SIDE 3 |
| 45 | |
| 46 | typedef struct RiceContext { |
| 47 | int history_mult; |
| 48 | int initial_history; |
| 49 | int k_modifier; |
| 50 | int rice_modifier; |
| 51 | } RiceContext; |
| 52 | |
| 53 | typedef struct AlacLPCContext { |
| 54 | int lpc_order; |
| 55 | int lpc_coeff[ALAC_MAX_LPC_ORDER+1]; |
| 56 | int lpc_quant; |
| 57 | } AlacLPCContext; |
| 58 | |
| 59 | typedef struct AlacEncodeContext { |
| 60 | int frame_size; /**< current frame size */ |
| 61 | int verbatim; /**< current frame verbatim mode flag */ |
| 62 | int compression_level; |
| 63 | int min_prediction_order; |
| 64 | int max_prediction_order; |
| 65 | int max_coded_frame_size; |
| 66 | int write_sample_size; |
| 67 | int extra_bits; |
| 68 | int32_t sample_buf[2][DEFAULT_FRAME_SIZE]; |
| 69 | int32_t predictor_buf[2][DEFAULT_FRAME_SIZE]; |
| 70 | int interlacing_shift; |
| 71 | int interlacing_leftweight; |
| 72 | PutBitContext pbctx; |
| 73 | RiceContext rc; |
| 74 | AlacLPCContext lpc[2]; |
| 75 | LPCContext lpc_ctx; |
| 76 | AVCodecContext *avctx; |
| 77 | } AlacEncodeContext; |
| 78 | |
| 79 | |
| 80 | static void init_sample_buffers(AlacEncodeContext *s, int channels, |
| 81 | uint8_t const *samples[2]) |
| 82 | { |
| 83 | int ch, i; |
| 84 | int shift = av_get_bytes_per_sample(s->avctx->sample_fmt) * 8 - |
| 85 | s->avctx->bits_per_raw_sample; |
| 86 | |
| 87 | #define COPY_SAMPLES(type) do { \ |
| 88 | for (ch = 0; ch < channels; ch++) { \ |
| 89 | int32_t *bptr = s->sample_buf[ch]; \ |
| 90 | const type *sptr = (const type *)samples[ch]; \ |
| 91 | for (i = 0; i < s->frame_size; i++) \ |
| 92 | bptr[i] = sptr[i] >> shift; \ |
| 93 | } \ |
| 94 | } while (0) |
| 95 | |
| 96 | if (s->avctx->sample_fmt == AV_SAMPLE_FMT_S32P) |
| 97 | COPY_SAMPLES(int32_t); |
| 98 | else |
| 99 | COPY_SAMPLES(int16_t); |
| 100 | } |
| 101 | |
| 102 | static void encode_scalar(AlacEncodeContext *s, int x, |
| 103 | int k, int write_sample_size) |
| 104 | { |
| 105 | int divisor, q, r; |
| 106 | |
| 107 | k = FFMIN(k, s->rc.k_modifier); |
| 108 | divisor = (1<<k) - 1; |
| 109 | q = x / divisor; |
| 110 | r = x % divisor; |
| 111 | |
| 112 | if (q > 8) { |
| 113 | // write escape code and sample value directly |
| 114 | put_bits(&s->pbctx, 9, ALAC_ESCAPE_CODE); |
| 115 | put_bits(&s->pbctx, write_sample_size, x); |
| 116 | } else { |
| 117 | if (q) |
| 118 | put_bits(&s->pbctx, q, (1<<q) - 1); |
| 119 | put_bits(&s->pbctx, 1, 0); |
| 120 | |
| 121 | if (k != 1) { |
| 122 | if (r > 0) |
| 123 | put_bits(&s->pbctx, k, r+1); |
| 124 | else |
| 125 | put_bits(&s->pbctx, k-1, 0); |
| 126 | } |
| 127 | } |
| 128 | } |
| 129 | |
| 130 | static void write_element_header(AlacEncodeContext *s, |
| 131 | enum AlacRawDataBlockType element, |
| 132 | int instance) |
| 133 | { |
| 134 | int encode_fs = 0; |
| 135 | |
| 136 | if (s->frame_size < DEFAULT_FRAME_SIZE) |
| 137 | encode_fs = 1; |
| 138 | |
| 139 | put_bits(&s->pbctx, 3, element); // element type |
| 140 | put_bits(&s->pbctx, 4, instance); // element instance |
| 141 | put_bits(&s->pbctx, 12, 0); // unused header bits |
| 142 | put_bits(&s->pbctx, 1, encode_fs); // Sample count is in the header |
| 143 | put_bits(&s->pbctx, 2, s->extra_bits >> 3); // Extra bytes (for 24-bit) |
| 144 | put_bits(&s->pbctx, 1, s->verbatim); // Audio block is verbatim |
| 145 | if (encode_fs) |
| 146 | put_bits32(&s->pbctx, s->frame_size); // No. of samples in the frame |
| 147 | } |
| 148 | |
| 149 | static void calc_predictor_params(AlacEncodeContext *s, int ch) |
| 150 | { |
| 151 | int32_t coefs[MAX_LPC_ORDER][MAX_LPC_ORDER]; |
| 152 | int shift[MAX_LPC_ORDER]; |
| 153 | int opt_order; |
| 154 | |
| 155 | if (s->compression_level == 1) { |
| 156 | s->lpc[ch].lpc_order = 6; |
| 157 | s->lpc[ch].lpc_quant = 6; |
| 158 | s->lpc[ch].lpc_coeff[0] = 160; |
| 159 | s->lpc[ch].lpc_coeff[1] = -190; |
| 160 | s->lpc[ch].lpc_coeff[2] = 170; |
| 161 | s->lpc[ch].lpc_coeff[3] = -130; |
| 162 | s->lpc[ch].lpc_coeff[4] = 80; |
| 163 | s->lpc[ch].lpc_coeff[5] = -25; |
| 164 | } else { |
| 165 | opt_order = ff_lpc_calc_coefs(&s->lpc_ctx, s->sample_buf[ch], |
| 166 | s->frame_size, |
| 167 | s->min_prediction_order, |
| 168 | s->max_prediction_order, |
| 169 | ALAC_MAX_LPC_PRECISION, coefs, shift, |
| 170 | FF_LPC_TYPE_LEVINSON, 0, |
| 171 | ORDER_METHOD_EST, ALAC_MAX_LPC_SHIFT, 1); |
| 172 | |
| 173 | s->lpc[ch].lpc_order = opt_order; |
| 174 | s->lpc[ch].lpc_quant = shift[opt_order-1]; |
| 175 | memcpy(s->lpc[ch].lpc_coeff, coefs[opt_order-1], opt_order*sizeof(int)); |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n) |
| 180 | { |
| 181 | int i, best; |
| 182 | int32_t lt, rt; |
| 183 | uint64_t sum[4]; |
| 184 | uint64_t score[4]; |
| 185 | |
| 186 | /* calculate sum of 2nd order residual for each channel */ |
| 187 | sum[0] = sum[1] = sum[2] = sum[3] = 0; |
| 188 | for (i = 2; i < n; i++) { |
| 189 | lt = left_ch[i] - 2 * left_ch[i - 1] + left_ch[i - 2]; |
| 190 | rt = right_ch[i] - 2 * right_ch[i - 1] + right_ch[i - 2]; |
| 191 | sum[2] += FFABS((lt + rt) >> 1); |
| 192 | sum[3] += FFABS(lt - rt); |
| 193 | sum[0] += FFABS(lt); |
| 194 | sum[1] += FFABS(rt); |
| 195 | } |
| 196 | |
| 197 | /* calculate score for each mode */ |
| 198 | score[0] = sum[0] + sum[1]; |
| 199 | score[1] = sum[0] + sum[3]; |
| 200 | score[2] = sum[1] + sum[3]; |
| 201 | score[3] = sum[2] + sum[3]; |
| 202 | |
| 203 | /* return mode with lowest score */ |
| 204 | best = 0; |
| 205 | for (i = 1; i < 4; i++) { |
| 206 | if (score[i] < score[best]) |
| 207 | best = i; |
| 208 | } |
| 209 | return best; |
| 210 | } |
| 211 | |
| 212 | static void alac_stereo_decorrelation(AlacEncodeContext *s) |
| 213 | { |
| 214 | int32_t *left = s->sample_buf[0], *right = s->sample_buf[1]; |
| 215 | int i, mode, n = s->frame_size; |
| 216 | int32_t tmp; |
| 217 | |
| 218 | mode = estimate_stereo_mode(left, right, n); |
| 219 | |
| 220 | switch (mode) { |
| 221 | case ALAC_CHMODE_LEFT_RIGHT: |
| 222 | s->interlacing_leftweight = 0; |
| 223 | s->interlacing_shift = 0; |
| 224 | break; |
| 225 | case ALAC_CHMODE_LEFT_SIDE: |
| 226 | for (i = 0; i < n; i++) |
| 227 | right[i] = left[i] - right[i]; |
| 228 | s->interlacing_leftweight = 1; |
| 229 | s->interlacing_shift = 0; |
| 230 | break; |
| 231 | case ALAC_CHMODE_RIGHT_SIDE: |
| 232 | for (i = 0; i < n; i++) { |
| 233 | tmp = right[i]; |
| 234 | right[i] = left[i] - right[i]; |
| 235 | left[i] = tmp + (right[i] >> 31); |
| 236 | } |
| 237 | s->interlacing_leftweight = 1; |
| 238 | s->interlacing_shift = 31; |
| 239 | break; |
| 240 | default: |
| 241 | for (i = 0; i < n; i++) { |
| 242 | tmp = left[i]; |
| 243 | left[i] = (tmp + right[i]) >> 1; |
| 244 | right[i] = tmp - right[i]; |
| 245 | } |
| 246 | s->interlacing_leftweight = 1; |
| 247 | s->interlacing_shift = 1; |
| 248 | break; |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | static void alac_linear_predictor(AlacEncodeContext *s, int ch) |
| 253 | { |
| 254 | int i; |
| 255 | AlacLPCContext lpc = s->lpc[ch]; |
| 256 | int32_t *residual = s->predictor_buf[ch]; |
| 257 | |
| 258 | if (lpc.lpc_order == 31) { |
| 259 | residual[0] = s->sample_buf[ch][0]; |
| 260 | |
| 261 | for (i = 1; i < s->frame_size; i++) { |
| 262 | residual[i] = s->sample_buf[ch][i ] - |
| 263 | s->sample_buf[ch][i - 1]; |
| 264 | } |
| 265 | |
| 266 | return; |
| 267 | } |
| 268 | |
| 269 | // generalised linear predictor |
| 270 | |
| 271 | if (lpc.lpc_order > 0) { |
| 272 | int32_t *samples = s->sample_buf[ch]; |
| 273 | |
| 274 | // generate warm-up samples |
| 275 | residual[0] = samples[0]; |
| 276 | for (i = 1; i <= lpc.lpc_order; i++) |
| 277 | residual[i] = sign_extend(samples[i] - samples[i-1], s->write_sample_size); |
| 278 | |
| 279 | // perform lpc on remaining samples |
| 280 | for (i = lpc.lpc_order + 1; i < s->frame_size; i++) { |
| 281 | int sum = 1 << (lpc.lpc_quant - 1), res_val, j; |
| 282 | |
| 283 | for (j = 0; j < lpc.lpc_order; j++) { |
| 284 | sum += (samples[lpc.lpc_order-j] - samples[0]) * |
| 285 | lpc.lpc_coeff[j]; |
| 286 | } |
| 287 | |
| 288 | sum >>= lpc.lpc_quant; |
| 289 | sum += samples[0]; |
| 290 | residual[i] = sign_extend(samples[lpc.lpc_order+1] - sum, |
| 291 | s->write_sample_size); |
| 292 | res_val = residual[i]; |
| 293 | |
| 294 | if (res_val) { |
| 295 | int index = lpc.lpc_order - 1; |
| 296 | int neg = (res_val < 0); |
| 297 | |
| 298 | while (index >= 0 && (neg ? (res_val < 0) : (res_val > 0))) { |
| 299 | int val = samples[0] - samples[lpc.lpc_order - index]; |
| 300 | int sign = (val ? FFSIGN(val) : 0); |
| 301 | |
| 302 | if (neg) |
| 303 | sign *= -1; |
| 304 | |
| 305 | lpc.lpc_coeff[index] -= sign; |
| 306 | val *= sign; |
| 307 | res_val -= (val >> lpc.lpc_quant) * (lpc.lpc_order - index); |
| 308 | index--; |
| 309 | } |
| 310 | } |
| 311 | samples++; |
| 312 | } |
| 313 | } |
| 314 | } |
| 315 | |
| 316 | static void alac_entropy_coder(AlacEncodeContext *s, int ch) |
| 317 | { |
| 318 | unsigned int history = s->rc.initial_history; |
| 319 | int sign_modifier = 0, i, k; |
| 320 | int32_t *samples = s->predictor_buf[ch]; |
| 321 | |
| 322 | for (i = 0; i < s->frame_size;) { |
| 323 | int x; |
| 324 | |
| 325 | k = av_log2((history >> 9) + 3); |
| 326 | |
| 327 | x = -2 * (*samples) -1; |
| 328 | x ^= x >> 31; |
| 329 | |
| 330 | samples++; |
| 331 | i++; |
| 332 | |
| 333 | encode_scalar(s, x - sign_modifier, k, s->write_sample_size); |
| 334 | |
| 335 | history += x * s->rc.history_mult - |
| 336 | ((history * s->rc.history_mult) >> 9); |
| 337 | |
| 338 | sign_modifier = 0; |
| 339 | if (x > 0xFFFF) |
| 340 | history = 0xFFFF; |
| 341 | |
| 342 | if (history < 128 && i < s->frame_size) { |
| 343 | unsigned int block_size = 0; |
| 344 | |
| 345 | k = 7 - av_log2(history) + ((history + 16) >> 6); |
| 346 | |
| 347 | while (*samples == 0 && i < s->frame_size) { |
| 348 | samples++; |
| 349 | i++; |
| 350 | block_size++; |
| 351 | } |
| 352 | encode_scalar(s, block_size, k, 16); |
| 353 | sign_modifier = (block_size <= 0xFFFF); |
| 354 | history = 0; |
| 355 | } |
| 356 | |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | static void write_element(AlacEncodeContext *s, |
| 361 | enum AlacRawDataBlockType element, int instance, |
| 362 | const uint8_t *samples0, const uint8_t *samples1) |
| 363 | { |
| 364 | uint8_t const *samples[2] = { samples0, samples1 }; |
| 365 | int i, j, channels; |
| 366 | int prediction_type = 0; |
| 367 | PutBitContext *pb = &s->pbctx; |
| 368 | |
| 369 | channels = element == TYPE_CPE ? 2 : 1; |
| 370 | |
| 371 | if (s->verbatim) { |
| 372 | write_element_header(s, element, instance); |
| 373 | /* samples are channel-interleaved in verbatim mode */ |
| 374 | if (s->avctx->sample_fmt == AV_SAMPLE_FMT_S32P) { |
| 375 | int shift = 32 - s->avctx->bits_per_raw_sample; |
| 376 | int32_t const *samples_s32[2] = { (const int32_t *)samples0, |
| 377 | (const int32_t *)samples1 }; |
| 378 | for (i = 0; i < s->frame_size; i++) |
| 379 | for (j = 0; j < channels; j++) |
| 380 | put_sbits(pb, s->avctx->bits_per_raw_sample, |
| 381 | samples_s32[j][i] >> shift); |
| 382 | } else { |
| 383 | int16_t const *samples_s16[2] = { (const int16_t *)samples0, |
| 384 | (const int16_t *)samples1 }; |
| 385 | for (i = 0; i < s->frame_size; i++) |
| 386 | for (j = 0; j < channels; j++) |
| 387 | put_sbits(pb, s->avctx->bits_per_raw_sample, |
| 388 | samples_s16[j][i]); |
| 389 | } |
| 390 | } else { |
| 391 | s->write_sample_size = s->avctx->bits_per_raw_sample - s->extra_bits + |
| 392 | channels - 1; |
| 393 | |
| 394 | init_sample_buffers(s, channels, samples); |
| 395 | write_element_header(s, element, instance); |
| 396 | |
| 397 | // extract extra bits if needed |
| 398 | if (s->extra_bits) { |
| 399 | uint32_t mask = (1 << s->extra_bits) - 1; |
| 400 | for (j = 0; j < channels; j++) { |
| 401 | int32_t *extra = s->predictor_buf[j]; |
| 402 | int32_t *smp = s->sample_buf[j]; |
| 403 | for (i = 0; i < s->frame_size; i++) { |
| 404 | extra[i] = smp[i] & mask; |
| 405 | smp[i] >>= s->extra_bits; |
| 406 | } |
| 407 | } |
| 408 | } |
| 409 | |
| 410 | if (channels == 2) |
| 411 | alac_stereo_decorrelation(s); |
| 412 | else |
| 413 | s->interlacing_shift = s->interlacing_leftweight = 0; |
| 414 | put_bits(pb, 8, s->interlacing_shift); |
| 415 | put_bits(pb, 8, s->interlacing_leftweight); |
| 416 | |
| 417 | for (i = 0; i < channels; i++) { |
| 418 | calc_predictor_params(s, i); |
| 419 | |
| 420 | put_bits(pb, 4, prediction_type); |
| 421 | put_bits(pb, 4, s->lpc[i].lpc_quant); |
| 422 | |
| 423 | put_bits(pb, 3, s->rc.rice_modifier); |
| 424 | put_bits(pb, 5, s->lpc[i].lpc_order); |
| 425 | // predictor coeff. table |
| 426 | for (j = 0; j < s->lpc[i].lpc_order; j++) |
| 427 | put_sbits(pb, 16, s->lpc[i].lpc_coeff[j]); |
| 428 | } |
| 429 | |
| 430 | // write extra bits if needed |
| 431 | if (s->extra_bits) { |
| 432 | for (i = 0; i < s->frame_size; i++) { |
| 433 | for (j = 0; j < channels; j++) { |
| 434 | put_bits(pb, s->extra_bits, s->predictor_buf[j][i]); |
| 435 | } |
| 436 | } |
| 437 | } |
| 438 | |
| 439 | // apply lpc and entropy coding to audio samples |
| 440 | for (i = 0; i < channels; i++) { |
| 441 | alac_linear_predictor(s, i); |
| 442 | |
| 443 | // TODO: determine when this will actually help. for now it's not used. |
| 444 | if (prediction_type == 15) { |
| 445 | // 2nd pass 1st order filter |
| 446 | int32_t *residual = s->predictor_buf[i]; |
| 447 | for (j = s->frame_size - 1; j > 0; j--) |
| 448 | residual[j] -= residual[j - 1]; |
| 449 | } |
| 450 | alac_entropy_coder(s, i); |
| 451 | } |
| 452 | } |
| 453 | } |
| 454 | |
| 455 | static int write_frame(AlacEncodeContext *s, AVPacket *avpkt, |
| 456 | uint8_t * const *samples) |
| 457 | { |
| 458 | PutBitContext *pb = &s->pbctx; |
| 459 | const enum AlacRawDataBlockType *ch_elements = ff_alac_channel_elements[s->avctx->channels - 1]; |
| 460 | const uint8_t *ch_map = ff_alac_channel_layout_offsets[s->avctx->channels - 1]; |
| 461 | int ch, element, sce, cpe; |
| 462 | |
| 463 | init_put_bits(pb, avpkt->data, avpkt->size); |
| 464 | |
| 465 | ch = element = sce = cpe = 0; |
| 466 | while (ch < s->avctx->channels) { |
| 467 | if (ch_elements[element] == TYPE_CPE) { |
| 468 | write_element(s, TYPE_CPE, cpe, samples[ch_map[ch]], |
| 469 | samples[ch_map[ch + 1]]); |
| 470 | cpe++; |
| 471 | ch += 2; |
| 472 | } else { |
| 473 | write_element(s, TYPE_SCE, sce, samples[ch_map[ch]], NULL); |
| 474 | sce++; |
| 475 | ch++; |
| 476 | } |
| 477 | element++; |
| 478 | } |
| 479 | |
| 480 | put_bits(pb, 3, TYPE_END); |
| 481 | flush_put_bits(pb); |
| 482 | |
| 483 | return put_bits_count(pb) >> 3; |
| 484 | } |
| 485 | |
| 486 | static av_always_inline int get_max_frame_size(int frame_size, int ch, int bps) |
| 487 | { |
| 488 | int header_bits = 23 + 32 * (frame_size < DEFAULT_FRAME_SIZE); |
| 489 | return FFALIGN(header_bits + bps * ch * frame_size + 3, 8) / 8; |
| 490 | } |
| 491 | |
| 492 | static av_cold int alac_encode_close(AVCodecContext *avctx) |
| 493 | { |
| 494 | AlacEncodeContext *s = avctx->priv_data; |
| 495 | ff_lpc_end(&s->lpc_ctx); |
| 496 | av_freep(&avctx->extradata); |
| 497 | avctx->extradata_size = 0; |
| 498 | return 0; |
| 499 | } |
| 500 | |
| 501 | static av_cold int alac_encode_init(AVCodecContext *avctx) |
| 502 | { |
| 503 | AlacEncodeContext *s = avctx->priv_data; |
| 504 | int ret; |
| 505 | uint8_t *alac_extradata; |
| 506 | |
| 507 | avctx->frame_size = s->frame_size = DEFAULT_FRAME_SIZE; |
| 508 | |
| 509 | if (avctx->sample_fmt == AV_SAMPLE_FMT_S32P) { |
| 510 | if (avctx->bits_per_raw_sample != 24) |
| 511 | av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n"); |
| 512 | avctx->bits_per_raw_sample = 24; |
| 513 | } else { |
| 514 | avctx->bits_per_raw_sample = 16; |
| 515 | s->extra_bits = 0; |
| 516 | } |
| 517 | |
| 518 | // Set default compression level |
| 519 | if (avctx->compression_level == FF_COMPRESSION_DEFAULT) |
| 520 | s->compression_level = 2; |
| 521 | else |
| 522 | s->compression_level = av_clip(avctx->compression_level, 0, 2); |
| 523 | |
| 524 | // Initialize default Rice parameters |
| 525 | s->rc.history_mult = 40; |
| 526 | s->rc.initial_history = 10; |
| 527 | s->rc.k_modifier = 14; |
| 528 | s->rc.rice_modifier = 4; |
| 529 | |
| 530 | s->max_coded_frame_size = get_max_frame_size(avctx->frame_size, |
| 531 | avctx->channels, |
| 532 | avctx->bits_per_raw_sample); |
| 533 | |
| 534 | avctx->extradata = av_mallocz(ALAC_EXTRADATA_SIZE + FF_INPUT_BUFFER_PADDING_SIZE); |
| 535 | if (!avctx->extradata) { |
| 536 | ret = AVERROR(ENOMEM); |
| 537 | goto error; |
| 538 | } |
| 539 | avctx->extradata_size = ALAC_EXTRADATA_SIZE; |
| 540 | |
| 541 | alac_extradata = avctx->extradata; |
| 542 | AV_WB32(alac_extradata, ALAC_EXTRADATA_SIZE); |
| 543 | AV_WB32(alac_extradata+4, MKBETAG('a','l','a','c')); |
| 544 | AV_WB32(alac_extradata+12, avctx->frame_size); |
| 545 | AV_WB8 (alac_extradata+17, avctx->bits_per_raw_sample); |
| 546 | AV_WB8 (alac_extradata+21, avctx->channels); |
| 547 | AV_WB32(alac_extradata+24, s->max_coded_frame_size); |
| 548 | AV_WB32(alac_extradata+28, |
| 549 | avctx->sample_rate * avctx->channels * avctx->bits_per_raw_sample); // average bitrate |
| 550 | AV_WB32(alac_extradata+32, avctx->sample_rate); |
| 551 | |
| 552 | // Set relevant extradata fields |
| 553 | if (s->compression_level > 0) { |
| 554 | AV_WB8(alac_extradata+18, s->rc.history_mult); |
| 555 | AV_WB8(alac_extradata+19, s->rc.initial_history); |
| 556 | AV_WB8(alac_extradata+20, s->rc.k_modifier); |
| 557 | } |
| 558 | |
| 559 | s->min_prediction_order = DEFAULT_MIN_PRED_ORDER; |
| 560 | if (avctx->min_prediction_order >= 0) { |
| 561 | if (avctx->min_prediction_order < MIN_LPC_ORDER || |
| 562 | avctx->min_prediction_order > ALAC_MAX_LPC_ORDER) { |
| 563 | av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n", |
| 564 | avctx->min_prediction_order); |
| 565 | ret = AVERROR(EINVAL); |
| 566 | goto error; |
| 567 | } |
| 568 | |
| 569 | s->min_prediction_order = avctx->min_prediction_order; |
| 570 | } |
| 571 | |
| 572 | s->max_prediction_order = DEFAULT_MAX_PRED_ORDER; |
| 573 | if (avctx->max_prediction_order >= 0) { |
| 574 | if (avctx->max_prediction_order < MIN_LPC_ORDER || |
| 575 | avctx->max_prediction_order > ALAC_MAX_LPC_ORDER) { |
| 576 | av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n", |
| 577 | avctx->max_prediction_order); |
| 578 | ret = AVERROR(EINVAL); |
| 579 | goto error; |
| 580 | } |
| 581 | |
| 582 | s->max_prediction_order = avctx->max_prediction_order; |
| 583 | } |
| 584 | |
| 585 | if (s->max_prediction_order < s->min_prediction_order) { |
| 586 | av_log(avctx, AV_LOG_ERROR, |
| 587 | "invalid prediction orders: min=%d max=%d\n", |
| 588 | s->min_prediction_order, s->max_prediction_order); |
| 589 | ret = AVERROR(EINVAL); |
| 590 | goto error; |
| 591 | } |
| 592 | |
| 593 | s->avctx = avctx; |
| 594 | |
| 595 | if ((ret = ff_lpc_init(&s->lpc_ctx, avctx->frame_size, |
| 596 | s->max_prediction_order, |
| 597 | FF_LPC_TYPE_LEVINSON)) < 0) { |
| 598 | goto error; |
| 599 | } |
| 600 | |
| 601 | return 0; |
| 602 | error: |
| 603 | alac_encode_close(avctx); |
| 604 | return ret; |
| 605 | } |
| 606 | |
| 607 | static int alac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, |
| 608 | const AVFrame *frame, int *got_packet_ptr) |
| 609 | { |
| 610 | AlacEncodeContext *s = avctx->priv_data; |
| 611 | int out_bytes, max_frame_size, ret; |
| 612 | |
| 613 | s->frame_size = frame->nb_samples; |
| 614 | |
| 615 | if (frame->nb_samples < DEFAULT_FRAME_SIZE) |
| 616 | max_frame_size = get_max_frame_size(s->frame_size, avctx->channels, |
| 617 | avctx->bits_per_raw_sample); |
| 618 | else |
| 619 | max_frame_size = s->max_coded_frame_size; |
| 620 | |
| 621 | if ((ret = ff_alloc_packet2(avctx, avpkt, 2 * max_frame_size)) < 0) |
| 622 | return ret; |
| 623 | |
| 624 | /* use verbatim mode for compression_level 0 */ |
| 625 | if (s->compression_level) { |
| 626 | s->verbatim = 0; |
| 627 | s->extra_bits = avctx->bits_per_raw_sample - 16; |
| 628 | } else { |
| 629 | s->verbatim = 1; |
| 630 | s->extra_bits = 0; |
| 631 | } |
| 632 | |
| 633 | out_bytes = write_frame(s, avpkt, frame->extended_data); |
| 634 | |
| 635 | if (out_bytes > max_frame_size) { |
| 636 | /* frame too large. use verbatim mode */ |
| 637 | s->verbatim = 1; |
| 638 | s->extra_bits = 0; |
| 639 | out_bytes = write_frame(s, avpkt, frame->extended_data); |
| 640 | } |
| 641 | |
| 642 | avpkt->size = out_bytes; |
| 643 | *got_packet_ptr = 1; |
| 644 | return 0; |
| 645 | } |
| 646 | |
| 647 | AVCodec ff_alac_encoder = { |
| 648 | .name = "alac", |
| 649 | .long_name = NULL_IF_CONFIG_SMALL("ALAC (Apple Lossless Audio Codec)"), |
| 650 | .type = AVMEDIA_TYPE_AUDIO, |
| 651 | .id = AV_CODEC_ID_ALAC, |
| 652 | .priv_data_size = sizeof(AlacEncodeContext), |
| 653 | .init = alac_encode_init, |
| 654 | .encode2 = alac_encode_frame, |
| 655 | .close = alac_encode_close, |
| 656 | .capabilities = CODEC_CAP_SMALL_LAST_FRAME, |
| 657 | .channel_layouts = ff_alac_channel_layouts, |
| 658 | .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S32P, |
| 659 | AV_SAMPLE_FMT_S16P, |
| 660 | AV_SAMPLE_FMT_NONE }, |
| 661 | }; |