libavcodec/lagarith.c

   1 /*
   2  * Lagarith lossless decoder
   3  * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * Lagarith lossless decoder
  25  * @author Nathan Caldwell
  26  */
  27
  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"
  34
  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 };
  48
  49 typedef struct LagarithContext {
  50     AVCodecContext *avctx;
  51     DSPContext dsp;
  52     int zeros;                  /**< number of consecutive zero bytes encountered */
  53     int zeros_rem;              /**< number of zero bytes remaining to output */
  54     uint8_t *rgb_planes;
  55     int rgb_stride;
  56 } LagarithContext;
  57
  58 /**
  59  * Compute the 52bit mantissa of 1/(double)denom.
  60  * This crazy format uses floats in an entropy coder and we have to match x86
  61  * rounding exactly, thus ordinary floats aren't portable enough.
  62  * @param denom denominator
  63  * @return 52bit mantissa
  64  * @see softfloat_mul
  65  */
  66 static uint64_t softfloat_reciprocal(uint32_t denom)
  67 {
  68     int shift = av_log2(denom - 1) + 1;
  69     uint64_t ret = (1ULL << 52) / denom;
  70     uint64_t err = (1ULL << 52) - ret * denom;
  71     ret <<= shift;
  72     err <<= shift;
  73     err +=  denom / 2;
  74     return ret + err / denom;
  75 }
  76
  77 /**
  78  * (uint32_t)(x*f), where f has the given mantissa, and exponent 0
  79  * Used in combination with softfloat_reciprocal computes x/(double)denom.
  80  * @param x 32bit integer factor
  81  * @param mantissa mantissa of f with exponent 0
  82  * @return 32bit integer value (x*f)
  83  * @see softfloat_reciprocal
  84  */
  85 static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
  86 {
  87     uint64_t l = x * (mantissa & 0xffffffff);
  88     uint64_t h = x * (mantissa >> 32);
  89     h += l >> 32;
  90     l &= 0xffffffff;
  91     l += 1 << av_log2(h >> 21);
  92     h += l >> 32;
  93     return h >> 20;
  94 }
  95
  96 static uint8_t lag_calc_zero_run(int8_t x)
  97 {
  98     return (x << 1) ^ (x >> 7);
  99 }
 100
 101 static int lag_decode_prob(GetBitContext *gb, uint32_t *value)
 102 {
 103     static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };
 104     int i;
 105     int bit     = 0;
 106     int bits    = 0;
 107     int prevbit = 0;
 108     unsigned val;
 109
 110     for (i = 0; i < 7; i++) {
 111         if (prevbit && bit)
 112             break;
 113         prevbit = bit;
 114         bit = get_bits1(gb);
 115         if (bit && !prevbit)
 116             bits += series[i];
 117     }
 118     bits--;
 119     if (bits < 0 || bits > 31) {
 120         *value = 0;
 121         return -1;
 122     } else if (bits == 0) {
 123         *value = 0;
 124         return 0;
 125     }
 126
 127     val  = get_bits_long(gb, bits);
 128     val |= 1 << bits;
 129
 130     *value = val - 1;
 131
 132     return 0;
 133 }
 134
 135 static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)
 136 {
 137     int i, j, scale_factor;
 138     unsigned prob, cumulative_target;
 139     unsigned cumul_prob = 0;
 140     unsigned scaled_cumul_prob = 0;
 141
 142     rac->prob[0] = 0;
 143     rac->prob[257] = UINT_MAX;
 144     /* Read probabilities from bitstream */
 145     for (i = 1; i < 257; i++) {
 146         if (lag_decode_prob(gb, &rac->prob[i]) < 0) {
 147             av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");
 148             return -1;
 149         }
 150         if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {
 151             av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");
 152             return -1;
 153         }
 154         cumul_prob += rac->prob[i];
 155         if (!rac->prob[i]) {
 156             if (lag_decode_prob(gb, &prob)) {
 157                 av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");
 158                 return -1;
 159             }
 160             if (prob > 257 - i)
 161                 prob = 257 - i;
 162             for (j = 0; j < prob; j++)
 163                 rac->prob[++i] = 0;
 164         }
 165     }
 166
 167     if (!cumul_prob) {
 168         av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
 169         return -1;
 170     }
 171
 172     /* Scale probabilities so cumulative probability is an even power of 2. */
 173     scale_factor = av_log2(cumul_prob);
 174
 175     if (cumul_prob & (cumul_prob - 1)) {
 176         uint64_t mul = softfloat_reciprocal(cumul_prob);
 177         for (i = 1; i < 257; i++) {
 178             rac->prob[i] = softfloat_mul(rac->prob[i], mul);
 179             scaled_cumul_prob += rac->prob[i];
 180         }
 181
 182         scale_factor++;
 183         cumulative_target = 1 << scale_factor;
 184
 185         if (scaled_cumul_prob > cumulative_target) {
 186             av_log(rac->avctx, AV_LOG_ERROR,
 187                    "Scaled probabilities are larger than target!\n");
 188             return -1;
 189         }
 190
 191         scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
 192
 193         for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
 194             if (rac->prob[i]) {
 195                 rac->prob[i]++;
 196                 scaled_cumul_prob--;
 197             }
 198             /* Comment from reference source:
 199              * if (b & 0x80 == 0) {     // order of operations is 'wrong'; it has been left this way
 200              *                          // since the compression change is negligible and fixing it
 201              *                          // breaks backwards compatibility
 202              *      b =- (signed int)b;
 203              *      b &= 0xFF;
 204              * } else {
 205              *      b++;
 206              *      b &= 0x7f;
 207              * }
 208              */
 209         }
 210     }
 211
 212     rac->scale = scale_factor;
 213
 214     /* Fill probability array with cumulative probability for each symbol. */
 215     for (i = 1; i < 257; i++)
 216         rac->prob[i] += rac->prob[i - 1];
 217
 218     return 0;
 219 }
 220
 221 static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
 222                                       uint8_t *diff, int w, int *left,
 223                                       int *left_top)
 224 {
 225     /* This is almost identical to add_hfyu_median_prediction in dsputil.h.
 226      * However the &0xFF on the gradient predictor yealds incorrect output
 227      * for lagarith.
 228      */
 229     int i;
 230     uint8_t l, lt;
 231
 232     l  = *left;
 233     lt = *left_top;
 234
 235     for (i = 0; i < w; i++) {
 236         l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
 237         lt = src1[i];
 238         dst[i] = l;
 239     }
 240
 241     *left     = l;
 242     *left_top = lt;
 243 }
 244
 245 static void lag_pred_line(LagarithContext *l, uint8_t *buf,
 246                           int width, int stride, int line)
 247 {
 248     int L, TL;
 249
 250     if (!line) {
 251         int i, align_width = (width - 1) & ~31;
 252         /* Left prediction only for first line */
 253         L = l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1,
 254                                             align_width, buf[0]);
 255         for (i = align_width + 1; i < width; i++)
 256             buf[i] += buf[i - 1];
 257     } else {
 258         /* Left pixel is actually prev_row[width] */
 259         L = buf[width - stride - 1];
 260
 261         if (line == 1) {
 262             /* Second line, left predict first pixel, the rest of the line is median predicted
 263              * NOTE: In the case of RGB this pixel is top predicted */
 264             TL = l->avctx->pix_fmt == AV_PIX_FMT_YUV420P ? buf[-stride] : L;
 265         } else {
 266             /* Top left is 2 rows back, last pixel */
 267             TL = buf[width - (2 * stride) - 1];
 268         }
 269
 270         add_lag_median_prediction(buf, buf - stride, buf,
 271                                   width, &L, &TL);
 272     }
 273 }
 274
 275 static void lag_pred_line_yuy2(LagarithContext *l, uint8_t *buf,
 276                                int width, int stride, int line,
 277                                int is_luma)
 278 {
 279     int L, TL;
 280
 281     if (!line) {
 282         int i, align_width;
 283         if (is_luma) {
 284             buf++;
 285             width--;
 286         }
 287
 288         align_width = (width - 1) & ~31;
 289         l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1, align_width, buf[0]);
 290
 291         for (i = align_width + 1; i < width; i++)
 292             buf[i] += buf[i - 1];
 293
 294         return;
 295     }
 296     if (line == 1) {
 297         const int HEAD = is_luma ? 4 : 2;
 298         int i;
 299
 300         L  = buf[width - stride - 1];
 301         TL = buf[HEAD  - stride - 1];
 302         for (i = 0; i < HEAD; i++) {
 303             L += buf[i];
 304             buf[i] = L;
 305         }
 306         for (; i < width; i++) {
 307             L      = mid_pred(L & 0xFF, buf[i - stride], (L + buf[i - stride] - TL) & 0xFF) + buf[i];
 308             TL     = buf[i - stride];
 309             buf[i] = L;
 310         }
 311     } else {
 312         TL = buf[width - (2 * stride) - 1];
 313         L  = buf[width - stride - 1];
 314         l->dsp.add_hfyu_median_prediction(buf, buf - stride, buf, width,
 315                                           &L, &TL);
 316     }
 317 }
 318
 319 static int lag_decode_line(LagarithContext *l, lag_rac *rac,
 320                            uint8_t *dst, int width, int stride,
 321                            int esc_count)
 322 {
 323     int i = 0;
 324     int ret = 0;
 325
 326     if (!esc_count)
 327         esc_count = -1;
 328
 329     /* Output any zeros remaining from the previous run */
 330 handle_zeros:
 331     if (l->zeros_rem) {
 332         int count = FFMIN(l->zeros_rem, width - i);
 333         memset(dst + i, 0, count);
 334         i += count;
 335         l->zeros_rem -= count;
 336     }
 337
 338     while (i < width) {
 339         dst[i] = lag_get_rac(rac);
 340         ret++;
 341
 342         if (dst[i])
 343             l->zeros = 0;
 344         else
 345             l->zeros++;
 346
 347         i++;
 348         if (l->zeros == esc_count) {
 349             int index = lag_get_rac(rac);
 350             ret++;
 351
 352             l->zeros = 0;
 353
 354             l->zeros_rem = lag_calc_zero_run(index);
 355             goto handle_zeros;
 356         }
 357     }
 358     return ret;
 359 }
 360
 361 static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
 362                                     const uint8_t *src, const uint8_t *src_end,
 363                                     int width, int esc_count)
 364 {
 365     int i = 0;
 366     int count;
 367     uint8_t zero_run = 0;
 368     const uint8_t *src_start = src;
 369     uint8_t mask1 = -(esc_count < 2);
 370     uint8_t mask2 = -(esc_count < 3);
 371     uint8_t *end = dst + (width - 2);
 372
 373 output_zeros:
 374     if (l->zeros_rem) {
 375         count = FFMIN(l->zeros_rem, width - i);
 376         if (end - dst < count) {
 377             av_log(l->avctx, AV_LOG_ERROR, "Too many zeros remaining.\n");
 378             return AVERROR_INVALIDDATA;
 379         }
 380
 381         memset(dst, 0, count);
 382         l->zeros_rem -= count;
 383         dst += count;
 384     }
 385
 386     while (dst < end) {
 387         i = 0;
 388         while (!zero_run && dst + i < end) {
 389             i++;
 390             if (src + i >= src_end)
 391                 return AVERROR_INVALIDDATA;
 392             zero_run =
 393                 !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
 394         }
 395         if (zero_run) {
 396             zero_run = 0;
 397             i += esc_count;
 398             memcpy(dst, src, i);
 399             dst += i;
 400             l->zeros_rem = lag_calc_zero_run(src[i]);
 401
 402             src += i + 1;
 403             goto output_zeros;
 404         } else {
 405             memcpy(dst, src, i);
 406             src += i;
 407             dst += i;
 408         }
 409     }
 410     return src_start - src;
 411 }
 412
 413
 414
 415 static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
 416                                   int width, int height, int stride,
 417                                   const uint8_t *src, int src_size)
 418 {
 419     int i = 0;
 420     int read = 0;
 421     uint32_t length;
 422     uint32_t offset = 1;
 423     int esc_count = src[0];
 424     GetBitContext gb;
 425     lag_rac rac;
 426     const uint8_t *src_end = src + src_size;
 427
 428     rac.avctx = l->avctx;
 429     l->zeros = 0;
 430
 431     if (esc_count < 4) {
 432         length = width * height;
 433         if (esc_count && AV_RL32(src + 1) < length) {
 434             length = AV_RL32(src + 1);
 435             offset += 4;
 436         }
 437
 438         init_get_bits(&gb, src + offset, src_size * 8);
 439
 440         if (lag_read_prob_header(&rac, &gb) < 0)
 441             return -1;
 442
 443         ff_lag_rac_init(&rac, &gb, length - stride);
 444
 445         for (i = 0; i < height; i++)
 446             read += lag_decode_line(l, &rac, dst + (i * stride), width,
 447                                     stride, esc_count);
 448
 449         if (read > length)
 450             av_log(l->avctx, AV_LOG_WARNING,
 451                    "Output more bytes than length (%d of %d)\n", read,
 452                    length);
 453     } else if (esc_count < 8) {
 454         esc_count -= 4;
 455         if (esc_count > 0) {
 456             /* Zero run coding only, no range coding. */
 457             for (i = 0; i < height; i++) {
 458                 int res = lag_decode_zero_run_line(l, dst + (i * stride), src,
 459                                                    src_end, width, esc_count);
 460                 if (res < 0)
 461                     return res;
 462                 src += res;
 463             }
 464         } else {
 465             if (src_size < width * height)
 466                 return AVERROR_INVALIDDATA; // buffer not big enough
 467             /* Plane is stored uncompressed */
 468             for (i = 0; i < height; i++) {
 469                 memcpy(dst + (i * stride), src, width);
 470                 src += width;
 471             }
 472         }
 473     } else if (esc_count == 0xff) {
 474         /* Plane is a solid run of given value */
 475         for (i = 0; i < height; i++)
 476             memset(dst + i * stride, src[1], width);
 477         /* Do not apply prediction.
 478            Note: memset to 0 above, setting first value to src[1]
 479            and applying prediction gives the same result. */
 480         return 0;
 481     } else {
 482         av_log(l->avctx, AV_LOG_ERROR,
 483                "Invalid zero run escape code! (%#x)\n", esc_count);
 484         return -1;
 485     }
 486
 487     if (l->avctx->pix_fmt != AV_PIX_FMT_YUV422P) {
 488         for (i = 0; i < height; i++) {
 489             lag_pred_line(l, dst, width, stride, i);
 490             dst += stride;
 491         }
 492     } else {
 493         for (i = 0; i < height; i++) {
 494             lag_pred_line_yuy2(l, dst, width, stride, i,
 495                                width == l->avctx->width);
 496             dst += stride;
 497         }
 498     }
 499
 500     return 0;
 501 }
 502
 503 /**
 504  * Decode a frame.
 505  * @param avctx codec context
 506  * @param data output AVFrame
 507  * @param data_size size of output data or 0 if no picture is returned
 508  * @param avpkt input packet
 509  * @return number of consumed bytes on success or negative if decode fails
 510  */
 511 static int lag_decode_frame(AVCodecContext *avctx,
 512                             void *data, int *got_frame, AVPacket *avpkt)
 513 {
 514     const uint8_t *buf = avpkt->data;
 515     int buf_size = avpkt->size;
 516     LagarithContext *l = avctx->priv_data;
 517     ThreadFrame frame = { .f = data };
 518     AVFrame *const p  = data;
 519     uint8_t frametype = 0;
 520     uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
 521     uint32_t offs[4];
 522     uint8_t *srcs[4], *dst;
 523     int i, j, planes = 3;
 524
 525     p->key_frame = 1;
 526
 527     frametype = buf[0];
 528
 529     offset_gu = AV_RL32(buf + 1);
 530     offset_bv = AV_RL32(buf + 5);
 531
 532     switch (frametype) {
 533     case FRAME_SOLID_RGBA:
 534         avctx->pix_fmt = AV_PIX_FMT_RGB32;
 535
 536         if (ff_thread_get_buffer(avctx, &frame, 0) < 0) {
 537             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 538             return -1;
 539         }
 540
 541         dst = p->data[0];
 542         for (j = 0; j < avctx->height; j++) {
 543             for (i = 0; i < avctx->width; i++)
 544                 AV_WN32(dst + i * 4, offset_gu);
 545             dst += p->linesize[0];
 546         }
 547         break;
 548     case FRAME_ARITH_RGBA:
 549         avctx->pix_fmt = AV_PIX_FMT_RGB32;
 550         planes = 4;
 551         offset_ry += 4;
 552         offs[3] = AV_RL32(buf + 9);
 553     case FRAME_ARITH_RGB24:
 554     case FRAME_U_RGB24:
 555         if (frametype == FRAME_ARITH_RGB24 || frametype == FRAME_U_RGB24)
 556             avctx->pix_fmt = AV_PIX_FMT_RGB24;
 557
 558         if (ff_thread_get_buffer(avctx, &frame, 0) < 0) {
 559             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 560             return -1;
 561         }
 562
 563         offs[0] = offset_bv;
 564         offs[1] = offset_gu;
 565         offs[2] = offset_ry;
 566
 567         if (!l->rgb_planes) {
 568             l->rgb_stride = FFALIGN(avctx->width, 16);
 569             l->rgb_planes = av_malloc(l->rgb_stride * avctx->height * planes + 1);
 570             if (!l->rgb_planes) {
 571                 av_log(avctx, AV_LOG_ERROR, "cannot allocate temporary buffer\n");
 572                 return AVERROR(ENOMEM);
 573             }
 574         }
 575         for (i = 0; i < planes; i++)
 576             srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;
 577         if (offset_ry >= buf_size ||
 578             offset_gu >= buf_size ||
 579             offset_bv >= buf_size ||
 580             (planes == 4 && offs[3] >= buf_size)) {
 581             av_log(avctx, AV_LOG_ERROR,
 582                     "Invalid frame offsets\n");
 583             return AVERROR_INVALIDDATA;
 584         }
 585         for (i = 0; i < planes; i++)
 586             lag_decode_arith_plane(l, srcs[i],
 587                                    avctx->width, avctx->height,
 588                                    -l->rgb_stride, buf + offs[i],
 589                                    buf_size - offs[i]);
 590         dst = p->data[0];
 591         for (i = 0; i < planes; i++)
 592             srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;
 593         for (j = 0; j < avctx->height; j++) {
 594             for (i = 0; i < avctx->width; i++) {
 595                 uint8_t r, g, b, a;
 596                 r = srcs[0][i];
 597                 g = srcs[1][i];
 598                 b = srcs[2][i];
 599                 r += g;
 600                 b += g;
 601                 if (frametype == FRAME_ARITH_RGBA) {
 602                     a = srcs[3][i];
 603                     AV_WN32(dst + i * 4, MKBETAG(a, r, g, b));
 604                 } else {
 605                     dst[i * 3 + 0] = r;
 606                     dst[i * 3 + 1] = g;
 607                     dst[i * 3 + 2] = b;
 608                 }
 609             }
 610             dst += p->linesize[0];
 611             for (i = 0; i < planes; i++)
 612                 srcs[i] += l->rgb_stride;
 613         }
 614         break;
 615     case FRAME_ARITH_YUY2:
 616         avctx->pix_fmt = AV_PIX_FMT_YUV422P;
 617
 618         if (ff_thread_get_buffer(avctx, &frame, 0) < 0) {
 619             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 620             return -1;
 621         }
 622
 623         if (offset_ry >= buf_size ||
 624             offset_gu >= buf_size ||
 625             offset_bv >= buf_size) {
 626             av_log(avctx, AV_LOG_ERROR,
 627                    "Invalid frame offsets\n");
 628             return AVERROR_INVALIDDATA;
 629         }
 630
 631         lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
 632                                p->linesize[0], buf + offset_ry,
 633                                buf_size - offset_ry);
 634         lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
 635                                avctx->height, p->linesize[1],
 636                                buf + offset_gu, buf_size - offset_gu);
 637         lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
 638                                avctx->height, p->linesize[2],
 639                                buf + offset_bv, buf_size - offset_bv);
 640         break;
 641     case FRAME_ARITH_YV12:
 642         avctx->pix_fmt = AV_PIX_FMT_YUV420P;
 643
 644         if (ff_thread_get_buffer(avctx, &frame, 0) < 0) {
 645             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 646             return -1;
 647         }
 648
 649         if (offset_ry >= buf_size ||
 650             offset_gu >= buf_size ||
 651             offset_bv >= buf_size) {
 652             av_log(avctx, AV_LOG_ERROR,
 653                    "Invalid frame offsets\n");
 654             return AVERROR_INVALIDDATA;
 655         }
 656
 657         lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
 658                                p->linesize[0], buf + offset_ry,
 659                                buf_size - offset_ry);
 660         lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
 661                                avctx->height / 2, p->linesize[2],
 662                                buf + offset_gu, buf_size - offset_gu);
 663         lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
 664                                avctx->height / 2, p->linesize[1],
 665                                buf + offset_bv, buf_size - offset_bv);
 666         break;
 667     default:
 668         av_log(avctx, AV_LOG_ERROR,
 669                "Unsupported Lagarith frame type: %#x\n", frametype);
 670         return -1;
 671     }
 672
 673     *got_frame = 1;
 674
 675     return buf_size;
 676 }
 677
 678 static av_cold int lag_decode_init(AVCodecContext *avctx)
 679 {
 680     LagarithContext *l = avctx->priv_data;
 681     l->avctx = avctx;
 682
 683     ff_dsputil_init(&l->dsp, avctx);
 684
 685     return 0;
 686 }
 687
 688 static av_cold int lag_decode_end(AVCodecContext *avctx)
 689 {
 690     LagarithContext *l = avctx->priv_data;
 691
 692     av_freep(&l->rgb_planes);
 693
 694     return 0;
 695 }
 696
 697 AVCodec ff_lagarith_decoder = {
 698     .name           = "lagarith",
 699     .long_name      = NULL_IF_CONFIG_SMALL("Lagarith lossless"),
 700     .type           = AVMEDIA_TYPE_VIDEO,
 701     .id             = AV_CODEC_ID_LAGARITH,
 702     .priv_data_size = sizeof(LagarithContext),
 703     .init           = lag_decode_init,
 704     .close          = lag_decode_end,
 705     .decode         = lag_decode_frame,
 706     .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
 707 };