libavcodec/mss3.c

   1 /*
   2  * Microsoft Screen 3 (aka Microsoft ATC Screen) decoder
   3  * Copyright (c) 2012 Konstantin Shishkov
   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 /**
  23  * @file
  24  * Microsoft Screen 3 (aka Microsoft ATC Screen) decoder
  25  */
  26
  27 #include "libavutil/mem.h"
  28 #include "avcodec.h"
  29 #include "bytestream.h"
  30 #include "codec_internal.h"
  31 #include "decode.h"
  32 #include "mathops.h"
  33 #include "mss34dsp.h"
  34
  35 #define HEADER_SIZE 27
  36
  37 #define MODEL2_SCALE       13
  38 #define MODEL_SCALE        15
  39 #define MODEL256_SEC_SCALE  9
  40
  41 typedef struct Model2 {
  42     int      upd_val, till_rescale;
  43     unsigned zero_freq,  zero_weight;
  44     unsigned total_freq, total_weight;
  45 } Model2;
  46
  47 typedef struct Model {
  48     int weights[16], freqs[16];
  49     int num_syms;
  50     int tot_weight;
  51     int upd_val, max_upd_val, till_rescale;
  52 } Model;
  53
  54 typedef struct Model256 {
  55     int weights[256], freqs[256];
  56     int tot_weight;
  57     int secondary[68];
  58     int sec_size;
  59     int upd_val, max_upd_val, till_rescale;
  60 } Model256;
  61
  62 #define RAC_BOTTOM 0x01000000
  63 typedef struct RangeCoder {
  64     const uint8_t *src, *src_end;
  65
  66     uint32_t range, low;
  67     int got_error;
  68 } RangeCoder;
  69
  70 enum BlockType {
  71     FILL_BLOCK = 0,
  72     IMAGE_BLOCK,
  73     DCT_BLOCK,
  74     HAAR_BLOCK,
  75     SKIP_BLOCK
  76 };
  77
  78 typedef struct BlockTypeContext {
  79     int      last_type;
  80     Model    bt_model[5];
  81 } BlockTypeContext;
  82
  83 typedef struct FillBlockCoder {
  84     int      fill_val;
  85     Model    coef_model;
  86 } FillBlockCoder;
  87
  88 typedef struct ImageBlockCoder {
  89     Model256 esc_model, vec_entry_model;
  90     Model    vec_size_model;
  91     Model    vq_model[125];
  92 } ImageBlockCoder;
  93
  94 typedef struct DCTBlockCoder {
  95     int      *prev_dc;
  96     ptrdiff_t prev_dc_stride;
  97     int      prev_dc_height;
  98     int      quality;
  99     uint16_t qmat[64];
 100     Model    dc_model;
 101     Model2   sign_model;
 102     Model256 ac_model;
 103 } DCTBlockCoder;
 104
 105 typedef struct HaarBlockCoder {
 106     int      quality, scale;
 107     Model256 coef_model;
 108     Model    coef_hi_model;
 109 } HaarBlockCoder;
 110
 111 typedef struct MSS3Context {
 112     AVCodecContext   *avctx;
 113     AVFrame          *pic;
 114
 115     int              got_error;
 116     RangeCoder       coder;
 117     BlockTypeContext btype[3];
 118     FillBlockCoder   fill_coder[3];
 119     ImageBlockCoder  image_coder[3];
 120     DCTBlockCoder    dct_coder[3];
 121     HaarBlockCoder   haar_coder[3];
 122
 123     int              dctblock[64];
 124     int              hblock[16 * 16];
 125 } MSS3Context;
 126
 127
 128 static void model2_reset(Model2 *m)
 129 {
 130     m->zero_weight  = 1;
 131     m->total_weight = 2;
 132     m->zero_freq    = 0x1000;
 133     m->total_freq   = 0x2000;
 134     m->upd_val      = 4;
 135     m->till_rescale = 4;
 136 }
 137
 138 static void model2_update(Model2 *m, int bit)
 139 {
 140     unsigned scale;
 141
 142     if (!bit)
 143         m->zero_weight++;
 144     m->till_rescale--;
 145     if (m->till_rescale)
 146         return;
 147
 148     m->total_weight += m->upd_val;
 149     if (m->total_weight > 0x2000) {
 150         m->total_weight = (m->total_weight + 1) >> 1;
 151         m->zero_weight  = (m->zero_weight  + 1) >> 1;
 152         if (m->total_weight == m->zero_weight)
 153             m->total_weight = m->zero_weight + 1;
 154     }
 155     m->upd_val = m->upd_val * 5 >> 2;
 156     if (m->upd_val > 64)
 157         m->upd_val = 64;
 158     scale = 0x80000000u / m->total_weight;
 159     m->zero_freq    = m->zero_weight  * scale >> 18;
 160     m->total_freq   = m->total_weight * scale >> 18;
 161     m->till_rescale = m->upd_val;
 162 }
 163
 164 static void model_update(Model *m, int val)
 165 {
 166     int i, sum = 0;
 167     unsigned scale;
 168
 169     m->weights[val]++;
 170     m->till_rescale--;
 171     if (m->till_rescale)
 172         return;
 173     m->tot_weight += m->upd_val;
 174
 175     if (m->tot_weight > 0x8000) {
 176         m->tot_weight = 0;
 177         for (i = 0; i < m->num_syms; i++) {
 178             m->weights[i]  = (m->weights[i] + 1) >> 1;
 179             m->tot_weight +=  m->weights[i];
 180         }
 181     }
 182     scale = 0x80000000u / m->tot_weight;
 183     for (i = 0; i < m->num_syms; i++) {
 184         m->freqs[i] = sum * scale >> 16;
 185         sum += m->weights[i];
 186     }
 187
 188     m->upd_val = m->upd_val * 5 >> 2;
 189     if (m->upd_val > m->max_upd_val)
 190         m->upd_val = m->max_upd_val;
 191     m->till_rescale = m->upd_val;
 192 }
 193
 194 static void model_reset(Model *m)
 195 {
 196     int i;
 197
 198     m->tot_weight   = 0;
 199     for (i = 0; i < m->num_syms - 1; i++)
 200         m->weights[i] = 1;
 201     m->weights[m->num_syms - 1] = 0;
 202
 203     m->upd_val      = m->num_syms;
 204     m->till_rescale = 1;
 205     model_update(m, m->num_syms - 1);
 206     m->till_rescale =
 207     m->upd_val      = (m->num_syms + 6) >> 1;
 208 }
 209
 210 static av_cold void model_init(Model *m, int num_syms)
 211 {
 212     m->num_syms    = num_syms;
 213     m->max_upd_val = 8 * num_syms + 48;
 214
 215     model_reset(m);
 216 }
 217
 218 static void model256_update(Model256 *m, int val)
 219 {
 220     int i, sum = 0;
 221     unsigned scale;
 222     int send, sidx = 1;
 223
 224     m->weights[val]++;
 225     m->till_rescale--;
 226     if (m->till_rescale)
 227         return;
 228     m->tot_weight += m->upd_val;
 229
 230     if (m->tot_weight > 0x8000) {
 231         m->tot_weight = 0;
 232         for (i = 0; i < 256; i++) {
 233             m->weights[i]  = (m->weights[i] + 1) >> 1;
 234             m->tot_weight +=  m->weights[i];
 235         }
 236     }
 237     scale = 0x80000000u / m->tot_weight;
 238     m->secondary[0] = 0;
 239     for (i = 0; i < 256; i++) {
 240         m->freqs[i] = sum * scale >> 16;
 241         sum += m->weights[i];
 242         send = m->freqs[i] >> MODEL256_SEC_SCALE;
 243         while (sidx <= send)
 244             m->secondary[sidx++] = i - 1;
 245     }
 246     while (sidx < m->sec_size)
 247         m->secondary[sidx++] = 255;
 248
 249     m->upd_val = m->upd_val * 5 >> 2;
 250     if (m->upd_val > m->max_upd_val)
 251         m->upd_val = m->max_upd_val;
 252     m->till_rescale = m->upd_val;
 253 }
 254
 255 static void model256_reset(Model256 *m)
 256 {
 257     int i;
 258
 259     for (i = 0; i < 255; i++)
 260         m->weights[i] = 1;
 261     m->weights[255] = 0;
 262
 263     m->tot_weight   = 0;
 264     m->upd_val      = 256;
 265     m->till_rescale = 1;
 266     model256_update(m, 255);
 267     m->till_rescale =
 268     m->upd_val      = (256 + 6) >> 1;
 269 }
 270
 271 static av_cold void model256_init(Model256 *m)
 272 {
 273     m->max_upd_val = 8 * 256 + 48;
 274     m->sec_size    = (1 << 6) + 2;
 275
 276     model256_reset(m);
 277 }
 278
 279 static void rac_init(RangeCoder *c, const uint8_t *src, int size)
 280 {
 281     int i;
 282
 283     c->src       = src;
 284     c->src_end   = src + size;
 285     c->low       = 0;
 286     for (i = 0; i < FFMIN(size, 4); i++)
 287         c->low = (c->low << 8) | *c->src++;
 288     c->range     = 0xFFFFFFFF;
 289     c->got_error = 0;
 290 }
 291
 292 static void rac_normalise(RangeCoder *c)
 293 {
 294     for (;;) {
 295         c->range <<= 8;
 296         c->low   <<= 8;
 297         if (c->src < c->src_end) {
 298             c->low |= *c->src++;
 299         } else if (!c->low) {
 300             c->got_error = 1;
 301             c->low = 1;
 302         }
 303         if (c->low > c->range) {
 304             c->got_error = 1;
 305             c->low = 1;
 306         }
 307         if (c->range >= RAC_BOTTOM)
 308             return;
 309     }
 310 }
 311
 312 static int rac_get_bit(RangeCoder *c)
 313 {
 314     int bit;
 315
 316     c->range >>= 1;
 317
 318     bit = (c->range <= c->low);
 319     if (bit)
 320         c->low -= c->range;
 321
 322     if (c->range < RAC_BOTTOM)
 323         rac_normalise(c);
 324
 325     return bit;
 326 }
 327
 328 static int rac_get_bits(RangeCoder *c, int nbits)
 329 {
 330     int val;
 331
 332     c->range >>= nbits;
 333     val = c->low / c->range;
 334     c->low -= c->range * val;
 335
 336     if (c->range < RAC_BOTTOM)
 337         rac_normalise(c);
 338
 339     return val;
 340 }
 341
 342 static int rac_get_model2_sym(RangeCoder *c, Model2 *m)
 343 {
 344     int bit, helper;
 345
 346     helper = m->zero_freq * (c->range >> MODEL2_SCALE);
 347     bit    = (c->low >= helper);
 348     if (bit) {
 349         c->low   -= helper;
 350         c->range -= helper;
 351     } else {
 352         c->range  = helper;
 353     }
 354
 355     if (c->range < RAC_BOTTOM)
 356         rac_normalise(c);
 357
 358     model2_update(m, bit);
 359
 360     return bit;
 361 }
 362
 363 static int rac_get_model_sym(RangeCoder *c, Model *m)
 364 {
 365     int val;
 366     int end, end2;
 367     unsigned prob, prob2, helper;
 368
 369     prob       = 0;
 370     prob2      = c->range;
 371     c->range >>= MODEL_SCALE;
 372     val        = 0;
 373     end        = m->num_syms >> 1;
 374     end2       = m->num_syms;
 375     do {
 376         helper = m->freqs[end] * c->range;
 377         if (helper <= c->low) {
 378             val   = end;
 379             prob  = helper;
 380         } else {
 381             end2  = end;
 382             prob2 = helper;
 383         }
 384         end = (end2 + val) >> 1;
 385     } while (end != val);
 386     c->low  -= prob;
 387     c->range = prob2 - prob;
 388     if (c->range < RAC_BOTTOM)
 389         rac_normalise(c);
 390
 391     model_update(m, val);
 392
 393     return val;
 394 }
 395
 396 static int rac_get_model256_sym(RangeCoder *c, Model256 *m)
 397 {
 398     int val;
 399     int start, end;
 400     int ssym;
 401     unsigned prob, prob2, helper;
 402
 403     prob2      = c->range;
 404     c->range >>= MODEL_SCALE;
 405
 406     helper     = c->low / c->range;
 407     ssym       = helper >> MODEL256_SEC_SCALE;
 408     val        = m->secondary[ssym];
 409
 410     end = start = m->secondary[ssym + 1] + 1;
 411     while (end > val + 1) {
 412         ssym = (end + val) >> 1;
 413         if (m->freqs[ssym] <= helper) {
 414             end = start;
 415             val = ssym;
 416         } else {
 417             end   = (end + val) >> 1;
 418             start = ssym;
 419         }
 420     }
 421     prob = m->freqs[val] * c->range;
 422     if (val != 255)
 423         prob2 = m->freqs[val + 1] * c->range;
 424
 425     c->low  -= prob;
 426     c->range = prob2 - prob;
 427     if (c->range < RAC_BOTTOM)
 428         rac_normalise(c);
 429
 430     model256_update(m, val);
 431
 432     return val;
 433 }
 434
 435 static int decode_block_type(RangeCoder *c, BlockTypeContext *bt)
 436 {
 437     bt->last_type = rac_get_model_sym(c, &bt->bt_model[bt->last_type]);
 438
 439     return bt->last_type;
 440 }
 441
 442 static int decode_coeff(RangeCoder *c, Model *m)
 443 {
 444     int val, sign;
 445
 446     val = rac_get_model_sym(c, m);
 447     if (val) {
 448         sign = rac_get_bit(c);
 449         if (val > 1) {
 450             val--;
 451             val = (1 << val) + rac_get_bits(c, val);
 452         }
 453         if (!sign)
 454             val = -val;
 455     }
 456
 457     return val;
 458 }
 459
 460 static void decode_fill_block(RangeCoder *c, FillBlockCoder *fc,
 461                               uint8_t *dst, ptrdiff_t stride, int block_size)
 462 {
 463     int i;
 464
 465     fc->fill_val += decode_coeff(c, &fc->coef_model);
 466
 467     for (i = 0; i < block_size; i++, dst += stride)
 468         memset(dst, fc->fill_val, block_size);
 469 }
 470
 471 static void decode_image_block(RangeCoder *c, ImageBlockCoder *ic,
 472                                uint8_t *dst, ptrdiff_t stride, int block_size)
 473 {
 474     int i, j;
 475     int vec_size;
 476     int vec[4];
 477     int prev_line[16];
 478     int A, B, C;
 479
 480     vec_size = rac_get_model_sym(c, &ic->vec_size_model) + 2;
 481     for (i = 0; i < vec_size; i++)
 482         vec[i] = rac_get_model256_sym(c, &ic->vec_entry_model);
 483     for (; i < 4; i++)
 484         vec[i] = 0;
 485     memset(prev_line, 0, sizeof(prev_line));
 486
 487     for (j = 0; j < block_size; j++) {
 488         A = 0;
 489         B = 0;
 490         for (i = 0; i < block_size; i++) {
 491             C = B;
 492             B = prev_line[i];
 493             A = rac_get_model_sym(c, &ic->vq_model[A + B * 5 + C * 25]);
 494
 495             prev_line[i] = A;
 496             if (A < 4)
 497                dst[i] = vec[A];
 498             else
 499                dst[i] = rac_get_model256_sym(c, &ic->esc_model);
 500         }
 501         dst += stride;
 502     }
 503 }
 504
 505 static int decode_dct(RangeCoder *c, DCTBlockCoder *bc, int *block,
 506                       int bx, int by)
 507 {
 508     int skip, val, sign, pos = 1, zz_pos, dc;
 509     int blk_pos = bx + by * bc->prev_dc_stride;
 510
 511     memset(block, 0, sizeof(*block) * 64);
 512
 513     dc = decode_coeff(c, &bc->dc_model);
 514     if (by) {
 515         if (bx) {
 516             int l, tl, t;
 517
 518             l  = bc->prev_dc[blk_pos - 1];
 519             tl = bc->prev_dc[blk_pos - 1 - bc->prev_dc_stride];
 520             t  = bc->prev_dc[blk_pos     - bc->prev_dc_stride];
 521
 522             if (FFABS(t - tl) <= FFABS(l - tl))
 523                 dc += l;
 524             else
 525                 dc += t;
 526         } else {
 527             dc += bc->prev_dc[blk_pos - bc->prev_dc_stride];
 528         }
 529     } else if (bx) {
 530         dc += bc->prev_dc[bx - 1];
 531     }
 532     bc->prev_dc[blk_pos] = dc;
 533     block[0]             = dc * bc->qmat[0];
 534
 535     while (pos < 64) {
 536         val = rac_get_model256_sym(c, &bc->ac_model);
 537         if (!val)
 538             return 0;
 539         if (val == 0xF0) {
 540             pos += 16;
 541             continue;
 542         }
 543         skip = val >> 4;
 544         val  = val & 0xF;
 545         if (!val)
 546             return -1;
 547         pos += skip;
 548         if (pos >= 64)
 549             return -1;
 550
 551         sign = rac_get_model2_sym(c, &bc->sign_model);
 552         if (val > 1) {
 553             val--;
 554             val = (1 << val) + rac_get_bits(c, val);
 555         }
 556         if (!sign)
 557             val = -val;
 558
 559         zz_pos = ff_zigzag_direct[pos];
 560         block[zz_pos] = val * bc->qmat[zz_pos];
 561         pos++;
 562     }
 563
 564     return pos == 64 ? 0 : -1;
 565 }
 566
 567 static void decode_dct_block(RangeCoder *c, DCTBlockCoder *bc,
 568                              uint8_t *dst, ptrdiff_t stride, int block_size,
 569                              int *block, int mb_x, int mb_y)
 570 {
 571     int i, j;
 572     int bx, by;
 573     int nblocks = block_size >> 3;
 574
 575     bx = mb_x * nblocks;
 576     by = mb_y * nblocks;
 577
 578     for (j = 0; j < nblocks; j++) {
 579         for (i = 0; i < nblocks; i++) {
 580             if (decode_dct(c, bc, block, bx + i, by + j)) {
 581                 c->got_error = 1;
 582                 return;
 583             }
 584             ff_mss34_dct_put(dst + i * 8, stride, block);
 585         }
 586         dst += 8 * stride;
 587     }
 588 }
 589
 590 static void decode_haar_block(RangeCoder *c, HaarBlockCoder *hc,
 591                               uint8_t *dst, ptrdiff_t stride,
 592                               int block_size, int *block)
 593 {
 594     const int hsize = block_size >> 1;
 595     int A, B, C, D, t1, t2, t3, t4;
 596     int i, j;
 597
 598     for (j = 0; j < block_size; j++) {
 599         for (i = 0; i < block_size; i++) {
 600             if (i < hsize && j < hsize)
 601                 block[i] = rac_get_model256_sym(c, &hc->coef_model);
 602             else
 603                 block[i] = decode_coeff(c, &hc->coef_hi_model);
 604             block[i] *= hc->scale;
 605         }
 606         block += block_size;
 607     }
 608     block -= block_size * block_size;
 609
 610     for (j = 0; j < hsize; j++) {
 611         for (i = 0; i < hsize; i++) {
 612             A = block[i];
 613             B = block[i + hsize];
 614             C = block[i + hsize * block_size];
 615             D = block[i + hsize * block_size + hsize];
 616
 617             t1 = A - B;
 618             t2 = C - D;
 619             t3 = A + B;
 620             t4 = C + D;
 621             dst[i * 2]              = av_clip_uint8(t1 - t2);
 622             dst[i * 2 + stride]     = av_clip_uint8(t1 + t2);
 623             dst[i * 2 + 1]          = av_clip_uint8(t3 - t4);
 624             dst[i * 2 + 1 + stride] = av_clip_uint8(t3 + t4);
 625         }
 626         block += block_size;
 627         dst   += stride * 2;
 628     }
 629 }
 630
 631 static void reset_coders(MSS3Context *ctx, int quality)
 632 {
 633     int i, j;
 634
 635     for (i = 0; i < 3; i++) {
 636         ctx->btype[i].last_type = SKIP_BLOCK;
 637         for (j = 0; j < 5; j++)
 638             model_reset(&ctx->btype[i].bt_model[j]);
 639         ctx->fill_coder[i].fill_val = 0;
 640         model_reset(&ctx->fill_coder[i].coef_model);
 641         model256_reset(&ctx->image_coder[i].esc_model);
 642         model256_reset(&ctx->image_coder[i].vec_entry_model);
 643         model_reset(&ctx->image_coder[i].vec_size_model);
 644         for (j = 0; j < 125; j++)
 645             model_reset(&ctx->image_coder[i].vq_model[j]);
 646         if (ctx->dct_coder[i].quality != quality) {
 647             ctx->dct_coder[i].quality = quality;
 648             ff_mss34_gen_quant_mat(ctx->dct_coder[i].qmat, quality, !i);
 649         }
 650         memset(ctx->dct_coder[i].prev_dc, 0,
 651                sizeof(*ctx->dct_coder[i].prev_dc) *
 652                ctx->dct_coder[i].prev_dc_stride *
 653                ctx->dct_coder[i].prev_dc_height);
 654         model_reset(&ctx->dct_coder[i].dc_model);
 655         model2_reset(&ctx->dct_coder[i].sign_model);
 656         model256_reset(&ctx->dct_coder[i].ac_model);
 657         if (ctx->haar_coder[i].quality != quality) {
 658             ctx->haar_coder[i].quality = quality;
 659             ctx->haar_coder[i].scale   = 17 - 7 * quality / 50;
 660         }
 661         model_reset(&ctx->haar_coder[i].coef_hi_model);
 662         model256_reset(&ctx->haar_coder[i].coef_model);
 663     }
 664 }
 665
 666 static av_cold void init_coders(MSS3Context *ctx)
 667 {
 668     int i, j;
 669
 670     for (i = 0; i < 3; i++) {
 671         for (j = 0; j < 5; j++)
 672             model_init(&ctx->btype[i].bt_model[j], 5);
 673         model_init(&ctx->fill_coder[i].coef_model, 12);
 674         model256_init(&ctx->image_coder[i].esc_model);
 675         model256_init(&ctx->image_coder[i].vec_entry_model);
 676         model_init(&ctx->image_coder[i].vec_size_model, 3);
 677         for (j = 0; j < 125; j++)
 678             model_init(&ctx->image_coder[i].vq_model[j], 5);
 679         model_init(&ctx->dct_coder[i].dc_model, 12);
 680         model256_init(&ctx->dct_coder[i].ac_model);
 681         model_init(&ctx->haar_coder[i].coef_hi_model, 12);
 682         model256_init(&ctx->haar_coder[i].coef_model);
 683     }
 684 }
 685
 686 static int mss3_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
 687                              int *got_frame, AVPacket *avpkt)
 688 {
 689     const uint8_t *buf = avpkt->data;
 690     int buf_size = avpkt->size;
 691     MSS3Context *c = avctx->priv_data;
 692     RangeCoder *acoder = &c->coder;
 693     GetByteContext gb;
 694     uint8_t *dst[3];
 695     int dec_width, dec_height, dec_x, dec_y, quality, keyframe;
 696     int x, y, i, mb_width, mb_height, blk_size, btype;
 697     int ret;
 698
 699     if (buf_size < HEADER_SIZE) {
 700         av_log(avctx, AV_LOG_ERROR,
 701                "Frame should have at least %d bytes, got %d instead\n",
 702                HEADER_SIZE, buf_size);
 703         return AVERROR_INVALIDDATA;
 704     }
 705
 706     bytestream2_init(&gb, buf, buf_size);
 707     keyframe   = bytestream2_get_be32(&gb);
 708     if (keyframe & ~0x301) {
 709         av_log(avctx, AV_LOG_ERROR, "Invalid frame type %X\n", keyframe);
 710         return AVERROR_INVALIDDATA;
 711     }
 712     keyframe   = !(keyframe & 1);
 713     bytestream2_skip(&gb, 6);
 714     dec_x      = bytestream2_get_be16(&gb);
 715     dec_y      = bytestream2_get_be16(&gb);
 716     dec_width  = bytestream2_get_be16(&gb);
 717     dec_height = bytestream2_get_be16(&gb);
 718
 719     if (dec_x + dec_width > avctx->width ||
 720         dec_y + dec_height > avctx->height ||
 721         (dec_width | dec_height) & 0xF) {
 722         av_log(avctx, AV_LOG_ERROR, "Invalid frame dimensions %dx%d +%d,%d\n",
 723                dec_width, dec_height, dec_x, dec_y);
 724         return AVERROR_INVALIDDATA;
 725     }
 726     bytestream2_skip(&gb, 4);
 727     quality    = bytestream2_get_byte(&gb);
 728     if (quality < 1 || quality > 100) {
 729         av_log(avctx, AV_LOG_ERROR, "Invalid quality setting %d\n", quality);
 730         return AVERROR_INVALIDDATA;
 731     }
 732     bytestream2_skip(&gb, 4);
 733
 734     if (keyframe && !bytestream2_get_bytes_left(&gb)) {
 735         av_log(avctx, AV_LOG_ERROR, "Keyframe without data found\n");
 736         return AVERROR_INVALIDDATA;
 737     }
 738     if (!keyframe && c->got_error)
 739         return buf_size;
 740     c->got_error = 0;
 741
 742     if ((ret = ff_reget_buffer(avctx, c->pic, 0)) < 0)
 743         return ret;
 744     if (keyframe)
 745         c->pic->flags |= AV_FRAME_FLAG_KEY;
 746     else
 747         c->pic->flags &= ~AV_FRAME_FLAG_KEY;
 748     c->pic->pict_type = keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
 749     if (!bytestream2_get_bytes_left(&gb)) {
 750         if ((ret = av_frame_ref(rframe, c->pic)) < 0)
 751             return ret;
 752         *got_frame      = 1;
 753
 754         return buf_size;
 755     }
 756
 757     reset_coders(c, quality);
 758
 759     rac_init(acoder, buf + HEADER_SIZE, buf_size - HEADER_SIZE);
 760
 761     mb_width  = dec_width  >> 4;
 762     mb_height = dec_height >> 4;
 763     dst[0] = c->pic->data[0] + dec_x     +  dec_y      * c->pic->linesize[0];
 764     dst[1] = c->pic->data[1] + dec_x / 2 + (dec_y / 2) * c->pic->linesize[1];
 765     dst[2] = c->pic->data[2] + dec_x / 2 + (dec_y / 2) * c->pic->linesize[2];
 766     for (y = 0; y < mb_height; y++) {
 767         for (x = 0; x < mb_width; x++) {
 768             for (i = 0; i < 3; i++) {
 769                 blk_size = 8 << !i;
 770
 771                 btype = decode_block_type(acoder, c->btype + i);
 772                 switch (btype) {
 773                 case FILL_BLOCK:
 774                     decode_fill_block(acoder, c->fill_coder + i,
 775                                       dst[i] + x * blk_size,
 776                                       c->pic->linesize[i], blk_size);
 777                     break;
 778                 case IMAGE_BLOCK:
 779                     decode_image_block(acoder, c->image_coder + i,
 780                                        dst[i] + x * blk_size,
 781                                        c->pic->linesize[i], blk_size);
 782                     break;
 783                 case DCT_BLOCK:
 784                     decode_dct_block(acoder, c->dct_coder + i,
 785                                      dst[i] + x * blk_size,
 786                                      c->pic->linesize[i], blk_size,
 787                                      c->dctblock, x, y);
 788                     break;
 789                 case HAAR_BLOCK:
 790                     decode_haar_block(acoder, c->haar_coder + i,
 791                                       dst[i] + x * blk_size,
 792                                       c->pic->linesize[i], blk_size,
 793                                       c->hblock);
 794                     break;
 795                 }
 796                 if (c->got_error || acoder->got_error) {
 797                     av_log(avctx, AV_LOG_ERROR, "Error decoding block %d,%d\n",
 798                            x, y);
 799                     c->got_error = 1;
 800                     return AVERROR_INVALIDDATA;
 801                 }
 802             }
 803         }
 804         dst[0] += c->pic->linesize[0] * 16;
 805         dst[1] += c->pic->linesize[1] * 8;
 806         dst[2] += c->pic->linesize[2] * 8;
 807     }
 808
 809     if ((ret = av_frame_ref(rframe, c->pic)) < 0)
 810         return ret;
 811
 812     *got_frame      = 1;
 813
 814     return buf_size;
 815 }
 816
 817 static av_cold int mss3_decode_end(AVCodecContext *avctx)
 818 {
 819     MSS3Context * const c = avctx->priv_data;
 820     int i;
 821
 822     av_frame_free(&c->pic);
 823     for (i = 0; i < 3; i++)
 824         av_freep(&c->dct_coder[i].prev_dc);
 825
 826     return 0;
 827 }
 828
 829 static av_cold int mss3_decode_init(AVCodecContext *avctx)
 830 {
 831     MSS3Context * const c = avctx->priv_data;
 832     int i;
 833
 834     c->avctx = avctx;
 835
 836     if ((avctx->width & 0xF) || (avctx->height & 0xF)) {
 837         av_log(avctx, AV_LOG_ERROR,
 838                "Image dimensions should be a multiple of 16.\n");
 839         return AVERROR_INVALIDDATA;
 840     }
 841
 842     c->got_error = 0;
 843     for (i = 0; i < 3; i++) {
 844         int b_width  = avctx->width  >> (2 + !!i);
 845         int b_height = avctx->height >> (2 + !!i);
 846         c->dct_coder[i].prev_dc_stride = b_width;
 847         c->dct_coder[i].prev_dc_height = b_height;
 848         c->dct_coder[i].prev_dc = av_malloc(sizeof(*c->dct_coder[i].prev_dc) *
 849                                             b_width * b_height);
 850         if (!c->dct_coder[i].prev_dc) {
 851             av_log(avctx, AV_LOG_ERROR, "Cannot allocate buffer\n");
 852             return AVERROR(ENOMEM);
 853         }
 854     }
 855
 856     c->pic = av_frame_alloc();
 857     if (!c->pic)
 858         return AVERROR(ENOMEM);
 859
 860     avctx->pix_fmt     = AV_PIX_FMT_YUV420P;
 861
 862     init_coders(c);
 863
 864     return 0;
 865 }
 866
 867 const FFCodec ff_msa1_decoder = {
 868     .p.name         = "msa1",
 869     CODEC_LONG_NAME("MS ATC Screen"),
 870     .p.type         = AVMEDIA_TYPE_VIDEO,
 871     .p.id           = AV_CODEC_ID_MSA1,
 872     .priv_data_size = sizeof(MSS3Context),
 873     .init           = mss3_decode_init,
 874     .close          = mss3_decode_end,
 875     FF_CODEC_DECODE_CB(mss3_decode_frame),
 876     .p.capabilities = AV_CODEC_CAP_DR1,
 877     .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
 878 };