FFmpeg: libavcodec/lagarith.c Source File

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lagarith.c

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1 /*

2 * Lagarith lossless decoder

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 */

22 /**

23 * @file

24 * Lagarith lossless decoder

25 * @author Nathan Caldwell

26 */

28 #include "avcodec.h"

29 #include "get_bits.h"

30 #include "mathops.h"

31 #include "dsputil.h"

32 #include "lagarithrac.h"

33 #include "thread.h"

35 enum LagarithFrameType {

36 FRAME_RAW = 1, /**< uncompressed */

37 FRAME_U_RGB24 = 2, /**< unaligned RGB24 */

38 FRAME_ARITH_YUY2 = 3, /**< arithmetic coded YUY2 */

39 FRAME_ARITH_RGB24 = 4, /**< arithmetic coded RGB24 */

40 FRAME_SOLID_GRAY = 5, /**< solid grayscale color frame */

41 FRAME_SOLID_COLOR = 6, /**< solid non-grayscale color frame */

42 FRAME_OLD_ARITH_RGB = 7, /**< obsolete arithmetic coded RGB (no longer encoded by upstream since version 1.1.0) */

43 FRAME_ARITH_RGBA = 8, /**< arithmetic coded RGBA */

44 FRAME_SOLID_RGBA = 9, /**< solid RGBA color frame */

45 FRAME_ARITH_YV12 = 10, /**< arithmetic coded YV12 */

46 FRAME_REDUCED_RES = 11, /**< reduced resolution YV12 frame */

47 };

49 typedef struct LagarithContext {

50 AVCodecContext *avctx;

51 AVFrame picture;

52 DSPContext dsp;

53 int zeros; /**< number of consecutive zero bytes encountered */

54 int zeros_rem; /**< number of zero bytes remaining to output */

55 uint8_t *rgb_planes;

56 int rgb_stride;

57 } LagarithContext;

59 /**

60 * Compute the 52bit mantissa of 1/(double)denom.

61 * This crazy format uses floats in an entropy coder and we have to match x86

62 * rounding exactly, thus ordinary floats aren't portable enough.

63 * @param denom denominator

64 * @return 52bit mantissa

65 * @see softfloat_mul

66 */

67 static uint64_t softfloat_reciprocal(uint32_t denom)

68 {

69 int shift = av_log2(denom - 1) + 1;

70 uint64_t ret = (1ULL << 52) / denom;

71 uint64_t err = (1ULL << 52) - ret * denom;

72 ret <<= shift;

73 err <<= shift;

74 err += denom / 2;

75 return ret + err / denom;

76 }

78 /**

79 * (uint32_t)(x*f), where f has the given mantissa, and exponent 0

80 * Used in combination with softfloat_reciprocal computes x/(double)denom.

81 * @param x 32bit integer factor

82 * @param mantissa mantissa of f with exponent 0

83 * @return 32bit integer value (x*f)

84 * @see softfloat_reciprocal

85 */

86 static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)

87 {

88 uint64_t l = x * (mantissa & 0xffffffff);

89 uint64_t h = x * (mantissa >> 32);

90 h += l >> 32;

91 l &= 0xffffffff;

92 l += 1 << av_log2(h >> 21);

93 h += l >> 32;

94 return h >> 20;

95 }

97 static uint8_t lag_calc_zero_run(int8_t x)

98 {

99 return (x << 1) ^ (x >> 7);

100 }

101

102 static int lag_decode_prob(GetBitContext *gb, uint32_t *value)

103 {

104 static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };

105 int i;

106 int bit = 0;

107 int bits = 0;

108 int prevbit = 0;

109 unsigned val;

110

111 for (i = 0; i < 7; i++) {

112 if (prevbit && bit)

113 break;

114 prevbit = bit;

115 bit = get_bits1(gb);

116 if (bit && !prevbit)

117 bits += series[i];

118 }

119 bits--;

120 if (bits < 0 || bits > 31) {

121 *value = 0;

122 return -1;

123 } else if (bits == 0) {

124 *value = 0;

125 return 0;

126 }

127

128 val = get_bits_long(gb, bits);

129 val |= 1 << bits;

130

131 *value = val - 1;

132

133 return 0;

134 }

135

136 static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)

137 {

138 int i, j, scale_factor;

139 unsigned prob, cumulative_target;

140 unsigned cumul_prob = 0;

141 unsigned scaled_cumul_prob = 0;

142

143 rac->prob[0] = 0;

144 rac->prob[257] = UINT_MAX;

145 /* Read probabilities from bitstream */

146 for (i = 1; i < 257; i++) {

147 if (lag_decode_prob(gb, &rac->prob[i]) < 0) {

148 av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");

149 return -1;

150 }

151 if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {

152 av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");

153 return -1;

154 }

155 cumul_prob += rac->prob[i];

156 if (!rac->prob[i]) {

157 if (lag_decode_prob(gb, &prob)) {

158 av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");

159 return -1;

160 }

161 if (prob > 256 - i)

162 prob = 256 - i;

163 for (j = 0; j < prob; j++)

164 rac->prob[++i] = 0;

165 }

166 }

167

168 if (!cumul_prob) {

169 av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");

170 return -1;

171 }

172

173 /* Scale probabilities so cumulative probability is an even power of 2. */

174 scale_factor = av_log2(cumul_prob);

175

176 if (cumul_prob & (cumul_prob - 1)) {

177 uint64_t mul = softfloat_reciprocal(cumul_prob);

178 for (i = 1; i < 257; i++) {

179 rac->prob[i] = softfloat_mul(rac->prob[i], mul);

180 scaled_cumul_prob += rac->prob[i];

181 }

182

183 scale_factor++;

184 cumulative_target = 1 << scale_factor;

185

186 if (scaled_cumul_prob > cumulative_target) {

187 av_log(rac->avctx, AV_LOG_ERROR,

188 "Scaled probabilities are larger than target!\n");

189 return -1;

190 }

191

192 scaled_cumul_prob = cumulative_target - scaled_cumul_prob;

193

194 for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {

195 if (rac->prob[i]) {

196 rac->prob[i]++;

197 scaled_cumul_prob--;

198 }

199 /* Comment from reference source:

200 * if (b & 0x80 == 0) { // order of operations is 'wrong'; it has been left this way

201 * // since the compression change is negligible and fixing it

202 * // breaks backwards compatibility

203 * b =- (signed int)b;

204 * b &= 0xFF;

205 * } else {

206 * b++;

207 * b &= 0x7f;

208 * }

209 */

210 }

211 }

212

213 rac->scale = scale_factor;

214

215 /* Fill probability array with cumulative probability for each symbol. */

216 for (i = 1; i < 257; i++)

217 rac->prob[i] += rac->prob[i - 1];

218

219 return 0;

220 }

221

222 static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,

223 uint8_t *diff, int w, int *left,

224 int *left_top)

225 {

226 /* This is almost identical to add_hfyu_median_prediction in dsputil.h.

227 * However the &0xFF on the gradient predictor yealds incorrect output

228 * for lagarith.

229 */

230 int i;

231 uint8_t l, lt;

232

233 l = *left;

234 lt = *left_top;

235

236 for (i = 0; i < w; i++) {

237 l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];

238 lt = src1[i];

239 dst[i] = l;

240 }

241

242 *left = l;

243 *left_top = lt;

244 }

245

246 static void lag_pred_line(LagarithContext *l, uint8_t *buf,

247 int width, int stride, int line)

248 {

249 int L, TL;

250

251 if (!line) {

252 /* Left prediction only for first line */

253 L = l->dsp.add_hfyu_left_prediction(buf, buf,

254 width, 0);

255 } else {

256 /* Left pixel is actually prev_row[width] */

257 L = buf[width - stride - 1];

258

259 if (line == 1) {

260 /* Second line, left predict first pixel, the rest of the line is median predicted

261 * NOTE: In the case of RGB this pixel is top predicted */

262 TL = l->avctx->pix_fmt == AV_PIX_FMT_YUV420P ? buf[-stride] : L;

263 } else {

264 /* Top left is 2 rows back, last pixel */

265 TL = buf[width - (2 * stride) - 1];

266 }

267

268 add_lag_median_prediction(buf, buf - stride, buf,

269 width, &L, &TL);

270 }

271 }

272

273 static void lag_pred_line_yuy2(LagarithContext *l, uint8_t *buf,

274 int width, int stride, int line,

275 int is_luma)

276 {

277 int L, TL;

278

279 if (!line) {

280 L= buf[0];

281 if (is_luma)

282 buf[0] = 0;

283 l->dsp.add_hfyu_left_prediction(buf, buf, width, 0);

284 if (is_luma)

285 buf[0] = L;

286 return;

287 }

288 if (line == 1) {

289 const int HEAD = is_luma ? 4 : 2;

290 int i;

291

292 L = buf[width - stride - 1];

293 TL = buf[HEAD - stride - 1];

294 for (i = 0; i < HEAD; i++) {

295 L += buf[i];

296 buf[i] = L;

297 }

298 for (; i<width; i++) {

299 L = mid_pred(L&0xFF, buf[i-stride], (L + buf[i-stride] - TL)&0xFF) + buf[i];

300 TL = buf[i-stride];

301 buf[i]= L;

302 }

303 } else {

304 TL = buf[width - (2 * stride) - 1];

305 L = buf[width - stride - 1];

306 l->dsp.add_hfyu_median_prediction(buf, buf - stride, buf, width,

307 &L, &TL);

308 }

309 }

310

311 static int lag_decode_line(LagarithContext *l, lag_rac *rac,

312 uint8_t *dst, int width, int stride,

313 int esc_count)

314 {

315 int i = 0;

316 int ret = 0;

317

318 if (!esc_count)

319 esc_count = -1;

320

321 /* Output any zeros remaining from the previous run */

322 handle_zeros:

323 if (l->zeros_rem) {

324 int count = FFMIN(l->zeros_rem, width - i);

325 memset(dst + i, 0, count);

326 i += count;

327 l->zeros_rem -= count;

328 }

329

330 while (i < width) {

331 dst[i] = lag_get_rac(rac);

332 ret++;

333

334 if (dst[i])

335 l->zeros = 0;

336 else

337 l->zeros++;

338

339 i++;

340 if (l->zeros == esc_count) {

341 int index = lag_get_rac(rac);

342 ret++;

343

344 l->zeros = 0;

345

346 l->zeros_rem = lag_calc_zero_run(index);

347 goto handle_zeros;

348 }

349 }

350 return ret;

351 }

352

353 static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,

354 const uint8_t *src, const uint8_t *src_end,

355 int width, int esc_count)

356 {

357 int i = 0;

358 int count;

359 uint8_t zero_run = 0;

360 const uint8_t *src_start = src;

361 uint8_t mask1 = -(esc_count < 2);

362 uint8_t mask2 = -(esc_count < 3);

363 uint8_t *end = dst + (width - 2);

364

365 output_zeros:

366 if (l->zeros_rem) {

367 count = FFMIN(l->zeros_rem, width - i);

368 if (end - dst < count) {

369 av_log(l->avctx, AV_LOG_ERROR, "Too many zeros remaining.\n");

370 return AVERROR_INVALIDDATA;

371 }

372

373 memset(dst, 0, count);

374 l->zeros_rem -= count;

375 dst += count;

376 }

377

378 while (dst < end) {

379 i = 0;

380 while (!zero_run && dst + i < end) {

381 i++;

382 if (i+2 >= src_end - src)

383 return AVERROR_INVALIDDATA;

384 zero_run =

385 !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));

386 }

387 if (zero_run) {

388 zero_run = 0;

389 i += esc_count;

390 memcpy(dst, src, i);

391 dst += i;

392 l->zeros_rem = lag_calc_zero_run(src[i]);

393

394 src += i + 1;

395 goto output_zeros;

396 } else {

397 memcpy(dst, src, i);

398 src += i;

399 dst += i;

400 }

401 }

402 return src - src_start;

403 }

404

405

406

407 static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,

408 int width, int height, int stride,

409 const uint8_t *src, int src_size)

410 {

411 int i = 0;

412 int read = 0;

413 uint32_t length;

414 uint32_t offset = 1;

415 int esc_count;

416 GetBitContext gb;

417 lag_rac rac;

418 const uint8_t *src_end = src + src_size;

419

420 rac.avctx = l->avctx;

421 l->zeros = 0;

422

423 if(src_size < 2)

424 return AVERROR_INVALIDDATA;

425

426 esc_count = src[0];

427 if (esc_count < 4) {

428 length = width * height;

429 if(src_size < 5)

430 return AVERROR_INVALIDDATA;

431 if (esc_count && AV_RL32(src + 1) < length) {

432 length = AV_RL32(src + 1);

433 offset += 4;

434 }

435

436 init_get_bits(&gb, src + offset, src_size * 8);

437

438 if (lag_read_prob_header(&rac, &gb) < 0)

439 return -1;

440

441 ff_lag_rac_init(&rac, &gb, length - stride);

442

443 for (i = 0; i < height; i++)

444 read += lag_decode_line(l, &rac, dst + (i * stride), width,

445 stride, esc_count);

446

447 if (read > length)

448 av_log(l->avctx, AV_LOG_WARNING,

449 "Output more bytes than length (%d of %d)\n", read,

450 length);

451 } else if (esc_count < 8) {

452 esc_count -= 4;

453 if (esc_count > 0) {

454 /* Zero run coding only, no range coding. */

455 for (i = 0; i < height; i++) {

456 int res = lag_decode_zero_run_line(l, dst + (i * stride), src,

457 src_end, width, esc_count);

458 if (res < 0)

459 return res;

460 src += res;

461 }

462 } else {

463 if (src_size < width * height)

464 return AVERROR_INVALIDDATA; // buffer not big enough

465 /* Plane is stored uncompressed */

466 for (i = 0; i < height; i++) {

467 memcpy(dst + (i * stride), src, width);

468 src += width;

469 }

470 }

471 } else if (esc_count == 0xff) {

472 /* Plane is a solid run of given value */

473 for (i = 0; i < height; i++)

474 memset(dst + i * stride, src[1], width);

475 /* Do not apply prediction.

476 Note: memset to 0 above, setting first value to src[1]

477 and applying prediction gives the same result. */

478 return 0;

479 } else {

480 av_log(l->avctx, AV_LOG_ERROR,

481 "Invalid zero run escape code! (%#x)\n", esc_count);

482 return -1;

483 }

484

485 if (l->avctx->pix_fmt != AV_PIX_FMT_YUV422P) {

486 for (i = 0; i < height; i++) {

487 lag_pred_line(l, dst, width, stride, i);

488 dst += stride;

489 }

490 } else {

491 for (i = 0; i < height; i++) {

492 lag_pred_line_yuy2(l, dst, width, stride, i,

493 width == l->avctx->width);

494 dst += stride;

495 }

496 }

497

498 return 0;

499 }

500

501 /**

502 * Decode a frame.

503 * @param avctx codec context

504 * @param data output AVFrame

505 * @param data_size size of output data or 0 if no picture is returned

506 * @param avpkt input packet

507 * @return number of consumed bytes on success or negative if decode fails

508 */

509 static int lag_decode_frame(AVCodecContext *avctx,

510 void *data, int *got_frame, AVPacket *avpkt)

511 {

512 const uint8_t *buf = avpkt->data;

513 unsigned int buf_size = avpkt->size;

514 LagarithContext *l = avctx->priv_data;

515 AVFrame *const p = &l->picture;

516 uint8_t frametype = 0;

517 uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;

518 uint32_t offs[4];

519 uint8_t *srcs[4], *dst;

520 int i, j, planes = 3;

521

522 AVFrame *picture = data;

523

524 if (p->data[0])

525 ff_thread_release_buffer(avctx, p);

526

527 p->reference = 0;

528 p->key_frame = 1;

529

530 frametype = buf[0];

531

532 offset_gu = AV_RL32(buf + 1);

533 offset_bv = AV_RL32(buf + 5);

534

535 switch (frametype) {

536 case FRAME_SOLID_RGBA:

537 avctx->pix_fmt = AV_PIX_FMT_RGB32;

538

539 if (ff_thread_get_buffer(avctx, p) < 0) {

540 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

541 return -1;

542 }

543

544 dst = p->data[0];

545 for (j = 0; j < avctx->height; j++) {

546 for (i = 0; i < avctx->width; i++)

547 AV_WN32(dst + i * 4, offset_gu);

548 dst += p->linesize[0];

549 }

550 break;

551 case FRAME_ARITH_RGBA:

552 avctx->pix_fmt = AV_PIX_FMT_RGB32;

553 planes = 4;

554 offset_ry += 4;

555 offs[3] = AV_RL32(buf + 9);

556 case FRAME_ARITH_RGB24:

557 case FRAME_U_RGB24:

558 if (frametype == FRAME_ARITH_RGB24 || frametype == FRAME_U_RGB24)

559 avctx->pix_fmt = AV_PIX_FMT_RGB24;

560

561 if (ff_thread_get_buffer(avctx, p) < 0) {

562 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

563 return -1;

564 }

565

566 offs[0] = offset_bv;

567 offs[1] = offset_gu;

568 offs[2] = offset_ry;

569

570 if (!l->rgb_planes) {

571 l->rgb_stride = FFALIGN(avctx->width, 16);

572 l->rgb_planes = av_malloc(l->rgb_stride * avctx->height * 4 + 16);

573 if (!l->rgb_planes) {

574 av_log(avctx, AV_LOG_ERROR, "cannot allocate temporary buffer\n");

575 return AVERROR(ENOMEM);

576 }

577 }

578 for (i = 0; i < planes; i++)

579 srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;

580 for (i = 0; i < planes; i++)

581 if (buf_size <= offs[i]) {

582 av_log(avctx, AV_LOG_ERROR,

583 "Invalid frame offsets\n");

584 return AVERROR_INVALIDDATA;

585 }

586

587 for (i = 0; i < planes; i++)

588 lag_decode_arith_plane(l, srcs[i],

589 avctx->width, avctx->height,

590 -l->rgb_stride, buf + offs[i],

591 buf_size - offs[i]);

592 dst = p->data[0];

593 for (i = 0; i < planes; i++)

594 srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;

595 for (j = 0; j < avctx->height; j++) {

596 for (i = 0; i < avctx->width; i++) {

597 uint8_t r, g, b, a;

598 r = srcs[0][i];

599 g = srcs[1][i];

600 b = srcs[2][i];

601 r += g;

602 b += g;

603 if (frametype == FRAME_ARITH_RGBA) {

604 a = srcs[3][i];

605 AV_WN32(dst + i * 4, MKBETAG(a, r, g, b));

606 } else {

607 dst[i * 3 + 0] = r;

608 dst[i * 3 + 1] = g;

609 dst[i * 3 + 2] = b;

610 }

611 }

612 dst += p->linesize[0];

613 for (i = 0; i < planes; i++)

614 srcs[i] += l->rgb_stride;

615 }

616 break;

617 case FRAME_ARITH_YUY2:

618 avctx->pix_fmt = AV_PIX_FMT_YUV422P;

619

620 if (ff_thread_get_buffer(avctx, p) < 0) {

621 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

622 return -1;

623 }

624

625 if (offset_ry >= buf_size ||

626 offset_gu >= buf_size ||

627 offset_bv >= buf_size) {

628 av_log(avctx, AV_LOG_ERROR,

629 "Invalid frame offsets\n");

630 return AVERROR_INVALIDDATA;

631 }

632

633 lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,

634 p->linesize[0], buf + offset_ry,

635 buf_size - offset_ry);

636 lag_decode_arith_plane(l, p->data[1], avctx->width / 2,

637 avctx->height, p->linesize[1],

638 buf + offset_gu, buf_size - offset_gu);

639 lag_decode_arith_plane(l, p->data[2], avctx->width / 2,

640 avctx->height, p->linesize[2],

641 buf + offset_bv, buf_size - offset_bv);

642 break;

643 case FRAME_ARITH_YV12:

644 avctx->pix_fmt = AV_PIX_FMT_YUV420P;

645

646 if (ff_thread_get_buffer(avctx, p) < 0) {

647 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

648 return -1;

649 }

650 if (buf_size <= offset_ry || buf_size <= offset_gu || buf_size <= offset_bv) {

651 return AVERROR_INVALIDDATA;

652 }

653

654 if (offset_ry >= buf_size ||

655 offset_gu >= buf_size ||

656 offset_bv >= buf_size) {

657 av_log(avctx, AV_LOG_ERROR,

658 "Invalid frame offsets\n");

659 return AVERROR_INVALIDDATA;

660 }

661

662 lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,

663 p->linesize[0], buf + offset_ry,

664 buf_size - offset_ry);

665 lag_decode_arith_plane(l, p->data[2], avctx->width / 2,

666 avctx->height / 2, p->linesize[2],

667 buf + offset_gu, buf_size - offset_gu);

668 lag_decode_arith_plane(l, p->data[1], avctx->width / 2,

669 avctx->height / 2, p->linesize[1],

670 buf + offset_bv, buf_size - offset_bv);

671 break;

672 default:

673 av_log(avctx, AV_LOG_ERROR,

674 "Unsupported Lagarith frame type: %#x\n", frametype);

675 return -1;

676 }

677

678 *picture = *p;

679 *got_frame = 1;

680

681 return buf_size;

682 }

683

684 static av_cold int lag_decode_init(AVCodecContext *avctx)

685 {

686 LagarithContext *l = avctx->priv_data;

687 l->avctx = avctx;

688

689 ff_dsputil_init(&l->dsp, avctx);

690

691 return 0;

692 }

693

694 static av_cold int lag_decode_end(AVCodecContext *avctx)

695 {

696 LagarithContext *l = avctx->priv_data;

697

698 if (l->picture.data[0])

699 ff_thread_release_buffer(avctx, &l->picture);

700 av_freep(&l->rgb_planes);

701

702 return 0;

703 }

704

705 AVCodec ff_lagarith_decoder = {

706 .name = "lagarith",

707 .type = AVMEDIA_TYPE_VIDEO,

708 .id = AV_CODEC_ID_LAGARITH,

709 .priv_data_size = sizeof(LagarithContext),

710 .init = lag_decode_init,

711 .close = lag_decode_end,

712 .decode = lag_decode_frame,

713 .capabilities = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,

714 .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),

715 };

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