libavcodec/mss12.c

   1 /*
   2  * Copyright (c) 2012 Konstantin Shishkov
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * Libav is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with Libav; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file
  23  * Common functions for Microsoft Screen 1 and 2
  24  */
  25
  26 #include <inttypes.h>
  27
  28 #include "libavutil/intfloat.h"
  29 #include "libavutil/intreadwrite.h"
  30 #include "avcodec.h"
  31 #include "mss12.h"
  32
  33 enum SplitMode {
  34     SPLIT_VERT = 0,
  35     SPLIT_HOR,
  36     SPLIT_NONE
  37 };
  38
  39 static const int sec_order_sizes[4] = { 1, 7, 6, 1 };
  40
  41 enum ContextDirection {
  42     TOP_LEFT = 0,
  43     TOP,
  44     TOP_RIGHT,
  45     LEFT
  46 };
  47
  48 static int model_calc_threshold(Model *m)
  49 {
  50     int thr;
  51
  52     thr = 2 * m->weights[m->num_syms] - 1;
  53     thr = ((thr >> 1) + 4 * m->cum_prob[0]) / thr;
  54
  55     return FFMIN(thr, 0x3FFF);
  56 }
  57
  58 static void model_reset(Model *m)
  59 {
  60     int i;
  61
  62     for (i = 0; i <= m->num_syms; i++) {
  63         m->weights[i]  = 1;
  64         m->cum_prob[i] = m->num_syms - i;
  65     }
  66     m->weights[0] = 0;
  67     for (i = 0; i < m->num_syms; i++)
  68         m->idx2sym[i + 1] = i;
  69 }
  70
  71 static av_cold void model_init(Model *m, int num_syms, int thr_weight)
  72 {
  73     m->num_syms   = num_syms;
  74     m->thr_weight = thr_weight;
  75     m->threshold  = num_syms * thr_weight;
  76 }
  77
  78 static void model_rescale_weights(Model *m)
  79 {
  80     int i;
  81     int cum_prob;
  82
  83     if (m->thr_weight == THRESH_ADAPTIVE)
  84         m->threshold = model_calc_threshold(m);
  85     while (m->cum_prob[0] > m->threshold) {
  86         cum_prob = 0;
  87         for (i = m->num_syms; i >= 0; i--) {
  88             m->cum_prob[i] = cum_prob;
  89             m->weights[i]  = (m->weights[i] + 1) >> 1;
  90             cum_prob      += m->weights[i];
  91         }
  92     }
  93 }
  94
  95 void ff_mss12_model_update(Model *m, int val)
  96 {
  97     int i;
  98
  99     if (m->weights[val] == m->weights[val - 1]) {
 100         for (i = val; m->weights[i - 1] == m->weights[val]; i--);
 101         if (i != val) {
 102             int sym1, sym2;
 103
 104             sym1 = m->idx2sym[val];
 105             sym2 = m->idx2sym[i];
 106
 107             m->idx2sym[val]  = sym2;
 108             m->idx2sym[i]    = sym1;
 109
 110             val = i;
 111         }
 112     }
 113     m->weights[val]++;
 114     for (i = val - 1; i >= 0; i--)
 115         m->cum_prob[i]++;
 116     model_rescale_weights(m);
 117 }
 118
 119 static void pixctx_reset(PixContext *ctx)
 120 {
 121     int i, j;
 122
 123     if (!ctx->special_initial_cache)
 124         for (i = 0; i < ctx->cache_size; i++)
 125             ctx->cache[i] = i;
 126     else {
 127         ctx->cache[0] = 1;
 128         ctx->cache[1] = 2;
 129         ctx->cache[2] = 4;
 130     }
 131
 132     model_reset(&ctx->cache_model);
 133     model_reset(&ctx->full_model);
 134
 135     for (i = 0; i < 15; i++)
 136         for (j = 0; j < 4; j++)
 137             model_reset(&ctx->sec_models[i][j]);
 138 }
 139
 140 static av_cold void pixctx_init(PixContext *ctx, int cache_size,
 141                                 int full_model_syms, int special_initial_cache)
 142 {
 143     int i, j, k, idx;
 144
 145     ctx->cache_size            = cache_size + 4;
 146     ctx->num_syms              = cache_size;
 147     ctx->special_initial_cache = special_initial_cache;
 148
 149     model_init(&ctx->cache_model, ctx->num_syms + 1, THRESH_LOW);
 150     model_init(&ctx->full_model, full_model_syms, THRESH_HIGH);
 151
 152     for (i = 0, idx = 0; i < 4; i++)
 153         for (j = 0; j < sec_order_sizes[i]; j++, idx++)
 154             for (k = 0; k < 4; k++)
 155                 model_init(&ctx->sec_models[idx][k], 2 + i,
 156                            i ? THRESH_LOW : THRESH_ADAPTIVE);
 157 }
 158
 159 static av_always_inline int decode_pixel(ArithCoder *acoder, PixContext *pctx,
 160                                          uint8_t *ngb, int num_ngb, int any_ngb)
 161 {
 162     int i, val, pix;
 163
 164     val = acoder->get_model_sym(acoder, &pctx->cache_model);
 165     if (val < pctx->num_syms) {
 166         if (any_ngb) {
 167             int idx, j;
 168
 169             idx = 0;
 170             for (i = 0; i < pctx->cache_size; i++) {
 171                 for (j = 0; j < num_ngb; j++)
 172                     if (pctx->cache[i] == ngb[j])
 173                         break;
 174                 if (j == num_ngb) {
 175                     if (idx == val)
 176                         break;
 177                     idx++;
 178                 }
 179             }
 180             val = FFMIN(i, pctx->cache_size - 1);
 181         }
 182         pix = pctx->cache[val];
 183     } else {
 184         pix = acoder->get_model_sym(acoder, &pctx->full_model);
 185         for (i = 0; i < pctx->cache_size - 1; i++)
 186             if (pctx->cache[i] == pix)
 187                 break;
 188         val = i;
 189     }
 190     if (val) {
 191         for (i = val; i > 0; i--)
 192             pctx->cache[i] = pctx->cache[i - 1];
 193         pctx->cache[0] = pix;
 194     }
 195
 196     return pix;
 197 }
 198
 199 static int decode_pixel_in_context(ArithCoder *acoder, PixContext *pctx,
 200                                    uint8_t *src, ptrdiff_t stride, int x, int y,
 201                                    int has_right)
 202 {
 203     uint8_t neighbours[4];
 204     uint8_t ref_pix[4];
 205     int nlen;
 206     int layer = 0, sub;
 207     int pix;
 208     int i, j;
 209
 210     if (!y) {
 211         memset(neighbours, src[-1], 4);
 212     } else {
 213         neighbours[TOP] = src[-stride];
 214         if (!x) {
 215             neighbours[TOP_LEFT] = neighbours[LEFT] = neighbours[TOP];
 216         } else {
 217             neighbours[TOP_LEFT] = src[-stride - 1];
 218             neighbours[    LEFT] = src[-1];
 219         }
 220         if (has_right)
 221             neighbours[TOP_RIGHT] = src[-stride + 1];
 222         else
 223             neighbours[TOP_RIGHT] = neighbours[TOP];
 224     }
 225
 226     sub = 0;
 227     if (x >= 2 && src[-2] == neighbours[LEFT])
 228         sub  = 1;
 229     if (y >= 2 && src[-2 * stride] == neighbours[TOP])
 230         sub |= 2;
 231
 232     nlen = 1;
 233     ref_pix[0] = neighbours[0];
 234     for (i = 1; i < 4; i++) {
 235         for (j = 0; j < nlen; j++)
 236             if (ref_pix[j] == neighbours[i])
 237                 break;
 238         if (j == nlen)
 239             ref_pix[nlen++] = neighbours[i];
 240     }
 241
 242     switch (nlen) {
 243     case 1:
 244         layer = 0;
 245         break;
 246     case 2:
 247         if (neighbours[TOP] == neighbours[TOP_LEFT]) {
 248             if (neighbours[TOP_RIGHT] == neighbours[TOP_LEFT])
 249                 layer = 1;
 250             else if (neighbours[LEFT] == neighbours[TOP_LEFT])
 251                 layer = 2;
 252             else
 253                 layer = 3;
 254         } else if (neighbours[TOP_RIGHT] == neighbours[TOP_LEFT]) {
 255             if (neighbours[LEFT] == neighbours[TOP_LEFT])
 256                 layer = 4;
 257             else
 258                 layer = 5;
 259         } else if (neighbours[LEFT] == neighbours[TOP_LEFT]) {
 260             layer = 6;
 261         } else {
 262             layer = 7;
 263         }
 264         break;
 265     case 3:
 266         if (neighbours[TOP] == neighbours[TOP_LEFT])
 267             layer = 8;
 268         else if (neighbours[TOP_RIGHT] == neighbours[TOP_LEFT])
 269             layer = 9;
 270         else if (neighbours[LEFT] == neighbours[TOP_LEFT])
 271             layer = 10;
 272         else if (neighbours[TOP_RIGHT] == neighbours[TOP])
 273             layer = 11;
 274         else if (neighbours[TOP] == neighbours[LEFT])
 275             layer = 12;
 276         else
 277             layer = 13;
 278         break;
 279     case 4:
 280         layer = 14;
 281         break;
 282     }
 283
 284     pix = acoder->get_model_sym(acoder,
 285                                 &pctx->sec_models[layer][sub]);
 286     if (pix < nlen)
 287         return ref_pix[pix];
 288     else
 289         return decode_pixel(acoder, pctx, ref_pix, nlen, 1);
 290 }
 291
 292 static int decode_region(ArithCoder *acoder, uint8_t *dst, uint8_t *rgb_pic,
 293                          int x, int y, int width, int height, ptrdiff_t stride,
 294                          ptrdiff_t rgb_stride, PixContext *pctx,
 295                          const uint32_t *pal)
 296 {
 297     int i, j, p;
 298     uint8_t *rgb_dst = rgb_pic + x * 3 + y * rgb_stride;
 299
 300     dst += x + y * stride;
 301
 302     for (j = 0; j < height; j++) {
 303         for (i = 0; i < width; i++) {
 304             if (!i && !j)
 305                 p = decode_pixel(acoder, pctx, NULL, 0, 0);
 306             else
 307                 p = decode_pixel_in_context(acoder, pctx, dst + i, stride,
 308                                             i, j, width - i - 1);
 309             dst[i] = p;
 310
 311             if (rgb_pic)
 312                 AV_WB24(rgb_dst + i * 3, pal[p]);
 313         }
 314         dst     += stride;
 315         rgb_dst += rgb_stride;
 316     }
 317
 318     return 0;
 319 }
 320
 321 static void copy_rectangles(MSS12Context const *c,
 322                             int x, int y, int width, int height)
 323 {
 324     int j;
 325
 326     if (c->last_rgb_pic)
 327         for (j = y; j < y + height; j++) {
 328             memcpy(c->rgb_pic      + j * c->rgb_stride + x * 3,
 329                    c->last_rgb_pic + j * c->rgb_stride + x * 3,
 330                    width * 3);
 331             memcpy(c->pal_pic      + j * c->pal_stride + x,
 332                    c->last_pal_pic + j * c->pal_stride + x,
 333                    width);
 334         }
 335 }
 336
 337 static int motion_compensation(MSS12Context const *c,
 338                                int x, int y, int width, int height)
 339 {
 340     if (x + c->mvX < 0 || x + c->mvX + width  > c->avctx->width  ||
 341         y + c->mvY < 0 || y + c->mvY + height > c->avctx->height ||
 342         !c->rgb_pic)
 343         return -1;
 344     else {
 345         uint8_t *dst     = c->pal_pic + x     + y * c->pal_stride;
 346         uint8_t *rgb_dst = c->rgb_pic + x * 3 + y * c->rgb_stride;
 347         uint8_t *src;
 348         uint8_t *rgb_src;
 349         int j;
 350         x += c->mvX;
 351         y += c->mvY;
 352         if (c->last_rgb_pic) {
 353             src     = c->last_pal_pic + x +     y * c->pal_stride;
 354             rgb_src = c->last_rgb_pic + x * 3 + y * c->rgb_stride;
 355         } else {
 356             src     = c->pal_pic + x     + y * c->pal_stride;
 357             rgb_src = c->rgb_pic + x * 3 + y * c->rgb_stride;
 358         }
 359         for (j = 0; j < height; j++) {
 360             memmove(dst, src, width);
 361             memmove(rgb_dst, rgb_src, width * 3);
 362             dst     += c->pal_stride;
 363             src     += c->pal_stride;
 364             rgb_dst += c->rgb_stride;
 365             rgb_src += c->rgb_stride;
 366         }
 367     }
 368     return 0;
 369 }
 370
 371 static int decode_region_masked(MSS12Context const *c, ArithCoder *acoder,
 372                                 uint8_t *dst, ptrdiff_t stride, uint8_t *mask,
 373                                 ptrdiff_t mask_stride, int x, int y,
 374                                 int width, int height,
 375                                 PixContext *pctx)
 376 {
 377     int i, j, p;
 378     uint8_t *rgb_dst = c->rgb_pic + x * 3 + y * c->rgb_stride;
 379
 380     dst  += x + y * stride;
 381     mask += x + y * mask_stride;
 382
 383     for (j = 0; j < height; j++) {
 384         for (i = 0; i < width; i++) {
 385             if (c->avctx->err_recognition & AV_EF_EXPLODE &&
 386                 ( c->rgb_pic && mask[i] != 0x01 && mask[i] != 0x02 && mask[i] != 0x04 ||
 387                  !c->rgb_pic && mask[i] != 0x80 && mask[i] != 0xFF))
 388                 return -1;
 389
 390             if (mask[i] == 0x02) {
 391                 copy_rectangles(c, x + i, y + j, 1, 1);
 392             } else if (mask[i] == 0x04) {
 393                 if (motion_compensation(c, x + i, y + j, 1, 1))
 394                     return -1;
 395             } else if (mask[i] != 0x80) {
 396                 if (!i && !j)
 397                     p = decode_pixel(acoder, pctx, NULL, 0, 0);
 398                 else
 399                     p = decode_pixel_in_context(acoder, pctx, dst + i, stride,
 400                                                 i, j, width - i - 1);
 401                 dst[i] = p;
 402                 if (c->rgb_pic)
 403                     AV_WB24(rgb_dst + i * 3, c->pal[p]);
 404             }
 405         }
 406         dst     += stride;
 407         mask    += mask_stride;
 408         rgb_dst += c->rgb_stride;
 409     }
 410
 411     return 0;
 412 }
 413
 414 static av_cold void slicecontext_init(SliceContext *sc,
 415                                       int version, int full_model_syms)
 416 {
 417     model_init(&sc->intra_region, 2, THRESH_ADAPTIVE);
 418     model_init(&sc->inter_region, 2, THRESH_ADAPTIVE);
 419     model_init(&sc->split_mode,   3, THRESH_HIGH);
 420     model_init(&sc->edge_mode,    2, THRESH_HIGH);
 421     model_init(&sc->pivot,        3, THRESH_LOW);
 422
 423     pixctx_init(&sc->intra_pix_ctx, 8, full_model_syms, 0);
 424
 425     pixctx_init(&sc->inter_pix_ctx, version ? 3 : 2,
 426                 full_model_syms, version ? 1 : 0);
 427 }
 428
 429 void ff_mss12_slicecontext_reset(SliceContext *sc)
 430 {
 431     model_reset(&sc->intra_region);
 432     model_reset(&sc->inter_region);
 433     model_reset(&sc->split_mode);
 434     model_reset(&sc->edge_mode);
 435     model_reset(&sc->pivot);
 436     pixctx_reset(&sc->intra_pix_ctx);
 437     pixctx_reset(&sc->inter_pix_ctx);
 438 }
 439
 440 static int decode_pivot(SliceContext *sc, ArithCoder *acoder, int base)
 441 {
 442     int val, inv;
 443
 444     inv = acoder->get_model_sym(acoder, &sc->edge_mode);
 445     val = acoder->get_model_sym(acoder, &sc->pivot) + 1;
 446
 447     if (val > 2) {
 448         if ((base + 1) / 2 - 2 <= 0)
 449             return -1;
 450
 451         val = acoder->get_number(acoder, (base + 1) / 2 - 2) + 3;
 452     }
 453
 454     if (val >= base)
 455         return -1;
 456
 457     return inv ? base - val : val;
 458 }
 459
 460 static int decode_region_intra(SliceContext *sc, ArithCoder *acoder,
 461                                int x, int y, int width, int height)
 462 {
 463     MSS12Context const *c = sc->c;
 464     int mode;
 465
 466     mode = acoder->get_model_sym(acoder, &sc->intra_region);
 467
 468     if (!mode) {
 469         int i, j, pix, rgb_pix;
 470         ptrdiff_t stride     = c->pal_stride;
 471         ptrdiff_t rgb_stride = c->rgb_stride;
 472         uint8_t *dst     = c->pal_pic + x     + y * stride;
 473         uint8_t *rgb_dst = c->rgb_pic + x * 3 + y * rgb_stride;
 474
 475         pix     = decode_pixel(acoder, &sc->intra_pix_ctx, NULL, 0, 0);
 476         rgb_pix = c->pal[pix];
 477         for (i = 0; i < height; i++, dst += stride, rgb_dst += rgb_stride) {
 478             memset(dst, pix, width);
 479             if (c->rgb_pic)
 480                 for (j = 0; j < width * 3; j += 3)
 481                     AV_WB24(rgb_dst + j, rgb_pix);
 482         }
 483     } else {
 484         return decode_region(acoder, c->pal_pic, c->rgb_pic,
 485                              x, y, width, height, c->pal_stride, c->rgb_stride,
 486                              &sc->intra_pix_ctx, &c->pal[0]);
 487     }
 488
 489     return 0;
 490 }
 491
 492 static int decode_region_inter(SliceContext *sc, ArithCoder *acoder,
 493                                int x, int y, int width, int height)
 494 {
 495     MSS12Context const *c = sc->c;
 496     int mode;
 497
 498     mode = acoder->get_model_sym(acoder, &sc->inter_region);
 499
 500     if (!mode) {
 501         mode = decode_pixel(acoder, &sc->inter_pix_ctx, NULL, 0, 0);
 502
 503         if (c->avctx->err_recognition & AV_EF_EXPLODE &&
 504             ( c->rgb_pic && mode != 0x01 && mode != 0x02 && mode != 0x04 ||
 505              !c->rgb_pic && mode != 0x80 && mode != 0xFF))
 506             return -1;
 507
 508         if (mode == 0x02)
 509             copy_rectangles(c, x, y, width, height);
 510         else if (mode == 0x04)
 511             return motion_compensation(c, x, y, width, height);
 512         else if (mode != 0x80)
 513             return decode_region_intra(sc, acoder, x, y, width, height);
 514     } else {
 515         if (decode_region(acoder, c->mask, NULL,
 516                           x, y, width, height, c->mask_stride, 0,
 517                           &sc->inter_pix_ctx, &c->pal[0]) < 0)
 518             return -1;
 519         return decode_region_masked(c, acoder, c->pal_pic,
 520                                     c->pal_stride, c->mask,
 521                                     c->mask_stride,
 522                                     x, y, width, height,
 523                                     &sc->intra_pix_ctx);
 524     }
 525
 526     return 0;
 527 }
 528
 529 int ff_mss12_decode_rect(SliceContext *sc, ArithCoder *acoder,
 530                          int x, int y, int width, int height)
 531 {
 532     int mode, pivot;
 533
 534     mode = acoder->get_model_sym(acoder, &sc->split_mode);
 535
 536     switch (mode) {
 537     case SPLIT_VERT:
 538         if ((pivot = decode_pivot(sc, acoder, height)) < 1)
 539             return -1;
 540         if (ff_mss12_decode_rect(sc, acoder, x, y, width, pivot))
 541             return -1;
 542         if (ff_mss12_decode_rect(sc, acoder, x, y + pivot, width, height - pivot))
 543             return -1;
 544         break;
 545     case SPLIT_HOR:
 546         if ((pivot = decode_pivot(sc, acoder, width)) < 1)
 547             return -1;
 548         if (ff_mss12_decode_rect(sc, acoder, x, y, pivot, height))
 549             return -1;
 550         if (ff_mss12_decode_rect(sc, acoder, x + pivot, y, width - pivot, height))
 551             return -1;
 552         break;
 553     case SPLIT_NONE:
 554         if (sc->c->keyframe)
 555             return decode_region_intra(sc, acoder, x, y, width, height);
 556         else
 557             return decode_region_inter(sc, acoder, x, y, width, height);
 558     default:
 559         return -1;
 560     }
 561
 562     return 0;
 563 }
 564
 565 av_cold int ff_mss12_decode_init(MSS12Context *c, int version,
 566                                  SliceContext* sc1, SliceContext *sc2)
 567 {
 568     AVCodecContext *avctx = c->avctx;
 569     int i;
 570
 571     if (avctx->extradata_size < 52 + 256 * 3) {
 572         av_log(avctx, AV_LOG_ERROR, "Insufficient extradata size %d\n",
 573                avctx->extradata_size);
 574         return AVERROR_INVALIDDATA;
 575     }
 576
 577     if (AV_RB32(avctx->extradata) < avctx->extradata_size) {
 578         av_log(avctx, AV_LOG_ERROR,
 579                "Insufficient extradata size: expected %"PRIu32" got %d\n",
 580                AV_RB32(avctx->extradata),
 581                avctx->extradata_size);
 582         return AVERROR_INVALIDDATA;
 583     }
 584
 585     avctx->coded_width  = AV_RB32(avctx->extradata + 20);
 586     avctx->coded_height = AV_RB32(avctx->extradata + 24);
 587     if (avctx->coded_width > 4096 || avctx->coded_height > 4096) {
 588         av_log(avctx, AV_LOG_ERROR, "Frame dimensions %dx%d too large",
 589                avctx->coded_width, avctx->coded_height);
 590         return AVERROR_INVALIDDATA;
 591     }
 592     if (avctx->width || avctx->height) {
 593         if (avctx->width  <= 0 || avctx->width > avctx->coded_width ||
 594             avctx->height <= 0 || avctx->height > avctx->coded_height) {
 595             av_log(avctx, AV_LOG_ERROR, "Invalid display dimensions\n");
 596             return AVERROR_INVALIDDATA;
 597         }
 598     } else {
 599         avctx->width  = avctx->coded_width;
 600         avctx->height = avctx->coded_height;
 601     }
 602
 603     av_log(avctx, AV_LOG_DEBUG, "Encoder version %"PRIu32".%"PRIu32"\n",
 604            AV_RB32(avctx->extradata + 4), AV_RB32(avctx->extradata + 8));
 605     if (version != AV_RB32(avctx->extradata + 4) > 1) {
 606         av_log(avctx, AV_LOG_ERROR,
 607                "Header version doesn't match codec tag\n");
 608         return -1;
 609     }
 610
 611     c->free_colours = AV_RB32(avctx->extradata + 48);
 612     if ((unsigned)c->free_colours > 256) {
 613         av_log(avctx, AV_LOG_ERROR,
 614                "Incorrect number of changeable palette entries: %d\n",
 615                c->free_colours);
 616         return AVERROR_INVALIDDATA;
 617     }
 618     av_log(avctx, AV_LOG_DEBUG, "%d free colour(s)\n", c->free_colours);
 619
 620     av_log(avctx, AV_LOG_DEBUG, "Display dimensions %"PRIu32"x%"PRIu32"\n",
 621            AV_RB32(avctx->extradata + 12), AV_RB32(avctx->extradata + 16));
 622     av_log(avctx, AV_LOG_DEBUG, "Coded dimensions %dx%d\n",
 623            avctx->coded_width, avctx->coded_height);
 624     av_log(avctx, AV_LOG_DEBUG, "%g frames per second\n",
 625            av_int2float(AV_RB32(avctx->extradata + 28)));
 626     av_log(avctx, AV_LOG_DEBUG, "Bitrate %"PRIu32" bps\n",
 627            AV_RB32(avctx->extradata + 32));
 628     av_log(avctx, AV_LOG_DEBUG, "Max. lead time %g ms\n",
 629            av_int2float(AV_RB32(avctx->extradata + 36)));
 630     av_log(avctx, AV_LOG_DEBUG, "Max. lag time %g ms\n",
 631            av_int2float(AV_RB32(avctx->extradata + 40)));
 632     av_log(avctx, AV_LOG_DEBUG, "Max. seek time %g ms\n",
 633            av_int2float(AV_RB32(avctx->extradata + 44)));
 634
 635     if (version) {
 636         if (avctx->extradata_size < 60 + 256 * 3) {
 637             av_log(avctx, AV_LOG_ERROR,
 638                    "Insufficient extradata size %d for v2\n",
 639                    avctx->extradata_size);
 640             return AVERROR_INVALIDDATA;
 641         }
 642
 643         c->slice_split = AV_RB32(avctx->extradata + 52);
 644         av_log(avctx, AV_LOG_DEBUG, "Slice split %d\n", c->slice_split);
 645
 646         c->full_model_syms = AV_RB32(avctx->extradata + 56);
 647         if (c->full_model_syms < 2 || c->full_model_syms > 256) {
 648             av_log(avctx, AV_LOG_ERROR,
 649                    "Incorrect number of used colours %d\n",
 650                    c->full_model_syms);
 651             return AVERROR_INVALIDDATA;
 652         }
 653         av_log(avctx, AV_LOG_DEBUG, "Used colours %d\n",
 654                c->full_model_syms);
 655     } else {
 656         c->slice_split     = 0;
 657         c->full_model_syms = 256;
 658     }
 659
 660     for (i = 0; i < 256; i++)
 661         c->pal[i] = AV_RB24(avctx->extradata + 52 +
 662                             (version ? 8 : 0) + i * 3);
 663
 664     c->mask_stride = FFALIGN(avctx->width, 16);
 665     c->mask        = av_malloc(c->mask_stride * avctx->height);
 666     if (!c->mask) {
 667         av_log(avctx, AV_LOG_ERROR, "Cannot allocate mask plane\n");
 668         return AVERROR(ENOMEM);
 669     }
 670
 671     sc1->c = c;
 672     slicecontext_init(sc1, version, c->full_model_syms);
 673     if (c->slice_split) {
 674         sc2->c = c;
 675         slicecontext_init(sc2, version, c->full_model_syms);
 676     }
 677     c->corrupted = 1;
 678
 679     return 0;
 680 }
 681
 682 av_cold int ff_mss12_decode_end(MSS12Context *c)
 683 {
 684     av_freep(&c->mask);
 685
 686     return 0;
 687 }