git.sesse.net Git - ffmpeg/blob - libavcodec/fmvc.c

   1 /*
   2  * FM Screen Capture Codec decoder
   3  *
   4  * Copyright (c) 2017 Paul B Mahol
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26
  27 #include "avcodec.h"
  28 #include "bytestream.h"
  29 #include "internal.h"
  30
  31 #define BLOCK_HEIGHT 112u
  32 #define BLOCK_WIDTH  84u
  33
  34 typedef struct InterBlock {
  35     int      w, h;
  36     int      size;
  37     int      xor;
  38 } InterBlock;
  39
  40 typedef struct FMVCContext {
  41     GetByteContext  gb;
  42     PutByteContext  pb;
  43     uint8_t        *buffer;
  44     size_t          buffer_size;
  45     uint8_t        *pbuffer;
  46     size_t          pbuffer_size;
  47     ptrdiff_t       stride;
  48     int             bpp;
  49     int             yb, xb;
  50     InterBlock     *blocks;
  51     unsigned        nb_blocks;
  52 } FMVCContext;
  53
  54 static int decode_type2(GetByteContext *gb, PutByteContext *pb)
  55 {
  56     unsigned repeat = 0, first = 1, opcode = 0;
  57     int i, len, pos;
  58
  59     while (bytestream2_get_bytes_left(gb) > 0) {
  60         GetByteContext gbc;
  61
  62         while (bytestream2_get_bytes_left(gb) > 0) {
  63             if (first) {
  64                 first = 0;
  65                 if (bytestream2_peek_byte(gb) > 17) {
  66                     len = bytestream2_get_byte(gb) - 17;
  67                     if (len < 4) {
  68                         do {
  69                             bytestream2_put_byte(pb, bytestream2_get_byte(gb));
  70                             --len;
  71                         } while (len);
  72                         opcode = bytestream2_peek_byte(gb);
  73                         continue;
  74                     } else {
  75                         do {
  76                             bytestream2_put_byte(pb, bytestream2_get_byte(gb));
  77                             --len;
  78                         } while (len);
  79                         opcode = bytestream2_peek_byte(gb);
  80                         if (opcode < 0x10) {
  81                             bytestream2_skip(gb, 1);
  82                             pos = - (opcode >> 2) - 4 * bytestream2_get_byte(gb) - 2049;
  83
  84                             bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
  85                             bytestream2_seek(&gbc, bytestream2_tell_p(pb) + pos, SEEK_SET);
  86
  87                             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
  88                             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
  89                             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
  90                             len = opcode & 3;
  91                             if (!len) {
  92                                 repeat = 1;
  93                             } else {
  94                                 do {
  95                                     bytestream2_put_byte(pb, bytestream2_get_byte(gb));
  96                                     --len;
  97                                 } while (len);
  98                                 opcode = bytestream2_peek_byte(gb);
  99                             }
 100                             continue;
 101                         }
 102                     }
 103                     repeat = 0;
 104                 }
 105                 repeat = 1;
 106             }
 107             if (repeat) {
 108                 repeat = 0;
 109                 opcode = bytestream2_peek_byte(gb);
 110                 if (opcode < 0x10) {
 111                     bytestream2_skip(gb, 1);
 112                     if (!opcode) {
 113                         if (!bytestream2_peek_byte(gb)) {
 114                             do {
 115                                 bytestream2_skip(gb, 1);
 116                                 opcode += 255;
 117                             } while (!bytestream2_peek_byte(gb) && bytestream2_get_bytes_left(gb) > 0);
 118                         }
 119                         opcode += bytestream2_get_byte(gb) + 15;
 120                     }
 121                     bytestream2_put_le32(pb, bytestream2_get_le32(gb));
 122                     for (i = opcode - 1; i > 0; --i)
 123                         bytestream2_put_byte(pb, bytestream2_get_byte(gb));
 124                     opcode = bytestream2_peek_byte(gb);
 125                     if (opcode < 0x10) {
 126                         bytestream2_skip(gb, 1);
 127                         pos = - (opcode >> 2) - 4 * bytestream2_get_byte(gb) - 2049;
 128
 129                         bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
 130                         bytestream2_seek(&gbc, bytestream2_tell_p(pb) + pos, SEEK_SET);
 131
 132                         bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 133                         bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 134                         bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 135                         len = opcode & 3;
 136                         if (!len) {
 137                             repeat = 1;
 138                         } else {
 139                             do {
 140                                 bytestream2_put_byte(pb, bytestream2_get_byte(gb));
 141                                 --len;
 142                             } while (len);
 143                             opcode = bytestream2_peek_byte(gb);
 144                         }
 145                         continue;
 146                     }
 147                 }
 148             }
 149
 150             if (opcode >= 0x40) {
 151                 bytestream2_skip(gb, 1);
 152                 pos = - ((opcode >> 2) & 7) - 1 - 8 * bytestream2_get_byte(gb);
 153                 len =    (opcode >> 5)      - 1;
 154
 155                 bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
 156                 bytestream2_seek(&gbc, bytestream2_tell_p(pb) + pos, SEEK_SET);
 157
 158                 bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 159                 bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 160                 do {
 161                     bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 162                     --len;
 163                 } while (len);
 164
 165                 len = opcode & 3;
 166
 167                 if (!len) {
 168                     repeat = 1;
 169                 } else {
 170                     do {
 171                         bytestream2_put_byte(pb, bytestream2_get_byte(gb));
 172                         --len;
 173                     } while (len);
 174                     opcode = bytestream2_peek_byte(gb);
 175                 }
 176                 continue;
 177             } else if (opcode < 0x20) {
 178                 break;
 179             }
 180             len = opcode & 0x1F;
 181             bytestream2_skip(gb, 1);
 182             if (!len) {
 183                 if (!bytestream2_peek_byte(gb)) {
 184                     do {
 185                         bytestream2_skip(gb, 1);
 186                         len += 255;
 187                     } while (!bytestream2_peek_byte(gb) && bytestream2_get_bytes_left(gb) > 0);
 188                 }
 189                 len += bytestream2_get_byte(gb) + 31;
 190             }
 191             i = bytestream2_get_le16(gb);
 192             pos = - (i >> 2) - 1;
 193
 194             bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
 195             bytestream2_seek(&gbc, bytestream2_tell_p(pb) + pos, SEEK_SET);
 196
 197             if (len < 6 || bytestream2_tell_p(pb) - bytestream2_tell(&gbc) < 4) {
 198                 bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 199                 bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 200                 do {
 201                     bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 202                     --len;
 203                 } while (len);
 204             } else {
 205                 bytestream2_put_le32(pb, bytestream2_get_le32(&gbc));
 206                 for (len = len - 2; len; --len)
 207                     bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 208             }
 209             len = i & 3;
 210             if (!len) {
 211                 repeat = 1;
 212             } else {
 213                 do {
 214                     bytestream2_put_byte(pb, bytestream2_get_byte(gb));
 215                     --len;
 216                 } while (len);
 217                 opcode = bytestream2_peek_byte(gb);
 218             }
 219         }
 220         bytestream2_skip(gb, 1);
 221         if (opcode < 0x10) {
 222             pos = -(opcode >> 2) - 1 - 4 * bytestream2_get_byte(gb);
 223
 224             bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
 225             bytestream2_seek(&gbc, bytestream2_tell_p(pb) + pos, SEEK_SET);
 226
 227             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 228             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 229             len = opcode & 3;
 230             if (!len) {
 231                 repeat = 1;
 232             } else {
 233                 do {
 234                     bytestream2_put_byte(pb, bytestream2_get_byte(gb));
 235                     --len;
 236                 } while (len);
 237                 opcode = bytestream2_peek_byte(gb);
 238             }
 239             continue;
 240         }
 241         len = opcode & 7;
 242         if (!len) {
 243             if (!bytestream2_peek_byte(gb)) {
 244                 do {
 245                     bytestream2_skip(gb, 1);
 246                     len += 255;
 247                 } while (!bytestream2_peek_byte(gb) && bytestream2_get_bytes_left(gb) > 0);
 248             }
 249             len += bytestream2_get_byte(gb) + 7;
 250         }
 251         i = bytestream2_get_le16(gb);
 252         pos = bytestream2_tell_p(pb) - 2048 * (opcode & 8);
 253         pos = pos - (i >> 2);
 254         if (pos == bytestream2_tell_p(pb))
 255             break;
 256
 257         pos = pos - 0x4000;
 258         bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
 259         bytestream2_seek(&gbc, pos, SEEK_SET);
 260
 261         if (len < 6 || bytestream2_tell_p(pb) - bytestream2_tell(&gbc) < 4) {
 262             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 263             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 264             do {
 265                 bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 266                 --len;
 267             } while (len);
 268         } else {
 269             bytestream2_put_le32(pb, bytestream2_get_le32(&gbc));
 270             for (len = len - 2; len; --len)
 271                 bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 272         }
 273
 274         len = i & 3;
 275         if (!len) {
 276             repeat = 1;
 277         } else {
 278             do {
 279                 bytestream2_put_byte(pb, bytestream2_get_byte(gb));
 280                 --len;
 281             } while (len);
 282             opcode = bytestream2_peek_byte(gb);
 283         }
 284     }
 285
 286     return 0;
 287 }
 288
 289 static int decode_type1(GetByteContext *gb, PutByteContext *pb)
 290 {
 291     unsigned opcode = 0, len;
 292     int high = 0;
 293     int i, pos;
 294
 295     while (bytestream2_get_bytes_left(gb) > 0) {
 296         GetByteContext gbc;
 297
 298         while (bytestream2_get_bytes_left(gb) > 0) {
 299             while (bytestream2_get_bytes_left(gb) > 0) {
 300                 opcode = bytestream2_get_byte(gb);
 301                 high = opcode >= 0x20;
 302                 if (high)
 303                     break;
 304                 if (opcode)
 305                     break;
 306                 opcode = bytestream2_get_byte(gb);
 307                 if (opcode < 0xF8) {
 308                     opcode += 32;
 309                     break;
 310                 }
 311                 i = opcode - 0xF8;
 312                 if (i) {
 313                     len = 256;
 314                     do {
 315                         len *= 2;
 316                         --i;
 317                     } while (i);
 318                 } else {
 319                     len = 280;
 320                 }
 321                 do {
 322                     bytestream2_put_le32(pb, bytestream2_get_le32(gb));
 323                     bytestream2_put_le32(pb, bytestream2_get_le32(gb));
 324                     len -= 8;
 325                 } while (len && bytestream2_get_bytes_left(gb) > 0);
 326             }
 327
 328             if (!high) {
 329                 do {
 330                     bytestream2_put_byte(pb, bytestream2_get_byte(gb));
 331                     --opcode;
 332                 } while (opcode && bytestream2_get_bytes_left(gb) > 0);
 333
 334                 while (bytestream2_get_bytes_left(gb) > 0) {
 335                     GetByteContext gbc;
 336
 337                     opcode = bytestream2_get_byte(gb);
 338                     if (opcode >= 0x20)
 339                         break;
 340                     bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
 341
 342                     pos = -(opcode | 32 * bytestream2_get_byte(gb)) - 1;
 343                     bytestream2_seek(&gbc, bytestream2_tell_p(pb) + pos, SEEK_SET);
 344                     bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 345                     bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 346                     bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 347                     bytestream2_put_byte(pb, bytestream2_get_byte(gb));
 348                 }
 349             }
 350             high = 0;
 351             if (opcode < 0x40)
 352                 break;
 353             bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
 354             pos = (-((opcode & 0x1F) | 32 * bytestream2_get_byte(gb)) - 1);
 355             bytestream2_seek(&gbc, bytestream2_tell_p(pb) + pos, SEEK_SET);
 356             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 357             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 358             len = (opcode >> 5) - 1;
 359             do {
 360                 bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 361                 --len;
 362             } while (len && bytestream2_get_bytes_left(&gbc) > 0);
 363         }
 364         len = opcode & 0x1F;
 365         if (!len) {
 366             if (!bytestream2_peek_byte(gb)) {
 367                 do {
 368                     bytestream2_skip(gb, 1);
 369                     len += 255;
 370                 } while (!bytestream2_peek_byte(gb) && bytestream2_get_bytes_left(gb) > 0);
 371             }
 372             len += bytestream2_get_byte(gb) + 31;
 373         }
 374         pos = -bytestream2_get_byte(gb);
 375         bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
 376         bytestream2_seek(&gbc, bytestream2_tell_p(pb) + pos - (bytestream2_get_byte(gb) << 8), SEEK_SET);
 377         if (bytestream2_tell_p(pb) == bytestream2_tell(&gbc))
 378             break;
 379         if (len < 5 || bytestream2_tell_p(pb) - bytestream2_tell(&gbc) < 4) {
 380             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 381             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 382             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 383         } else {
 384             bytestream2_put_le32(pb, bytestream2_get_le32(&gbc));
 385             len--;
 386         }
 387         do {
 388             bytestream2_put_byte(pb, bytestream2_get_byte(&gbc));
 389             len--;
 390         } while (len && bytestream2_get_bytes_left(&gbc) > 0);
 391     }
 392
 393     return 0;
 394 }
 395
 396 static int decode_frame(AVCodecContext *avctx, void *data,
 397                         int *got_frame, AVPacket *avpkt)
 398 {
 399     FMVCContext *s = avctx->priv_data;
 400     GetByteContext *gb = &s->gb;
 401     PutByteContext *pb = &s->pb;
 402     AVFrame *frame = data;
 403     int ret, y, x;
 404
 405     if (avpkt->size < 8)
 406         return AVERROR_INVALIDDATA;
 407
 408     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
 409         return ret;
 410
 411     bytestream2_init(gb, avpkt->data, avpkt->size);
 412     bytestream2_skip(gb, 2);
 413
 414     frame->key_frame = !!bytestream2_get_le16(gb);
 415     frame->pict_type = frame->key_frame ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
 416
 417     if (frame->key_frame) {
 418         const uint8_t *src;
 419         unsigned type, size;
 420         uint8_t *dst;
 421
 422         type = bytestream2_get_le16(gb);
 423         size = bytestream2_get_le16(gb);
 424         if (size > bytestream2_get_bytes_left(gb))
 425             return AVERROR_INVALIDDATA;
 426
 427         bytestream2_init_writer(pb, s->buffer, s->buffer_size);
 428         if (type == 1) {
 429             decode_type1(gb, pb);
 430         } else if (type == 2){
 431             decode_type2(gb, pb);
 432         } else {
 433             avpriv_report_missing_feature(avctx, "Compression type %d", type);
 434             return AVERROR_PATCHWELCOME;
 435         }
 436
 437         src = s->buffer;
 438         dst = frame->data[0] + (avctx->height - 1) * frame->linesize[0];
 439         for (y = 0; y < avctx->height; y++) {
 440             memcpy(dst, src, avctx->width * s->bpp);
 441             dst -= frame->linesize[0];
 442             src += s->stride * 4;
 443             if (bytestream2_tell_p(pb) < y*s->stride * 4)
 444                 break;
 445         }
 446     } else {
 447         unsigned block, nb_blocks;
 448         int type, k, l;
 449         uint8_t *ssrc, *ddst;
 450         const uint32_t *src;
 451         uint32_t *dst;
 452
 453         for (block = 0; block < s->nb_blocks; block++)
 454             s->blocks[block].xor = 0;
 455
 456         nb_blocks = bytestream2_get_le16(gb);
 457         if (nb_blocks > s->nb_blocks)
 458             return AVERROR_INVALIDDATA;
 459
 460         bytestream2_init_writer(pb, s->pbuffer, s->pbuffer_size);
 461
 462         type = bytestream2_get_le16(gb);
 463         for (block = 0; block < nb_blocks; block++) {
 464             unsigned size, offset;
 465             int start = 0;
 466
 467             offset = bytestream2_get_le16(gb);
 468             if (offset >= s->nb_blocks)
 469                 return AVERROR_INVALIDDATA;
 470
 471             size = bytestream2_get_le16(gb);
 472             if (size > bytestream2_get_bytes_left(gb))
 473                 return AVERROR_INVALIDDATA;
 474
 475             start = bytestream2_tell_p(pb);
 476             if (type == 1) {
 477                 decode_type1(gb, pb);
 478             } else if (type == 2){
 479                 decode_type2(gb, pb);
 480             } else {
 481                 avpriv_report_missing_feature(avctx, "Compression type %d", type);
 482                 return AVERROR_PATCHWELCOME;
 483             }
 484
 485             if (s->blocks[offset].size * 4 != bytestream2_tell_p(pb) - start)
 486                 return AVERROR_INVALIDDATA;
 487
 488             s->blocks[offset].xor = 1;
 489         }
 490
 491         src = (const uint32_t *)s->pbuffer;
 492         dst = (uint32_t *)s->buffer;
 493
 494         for (block = 0, y = 0; y < s->yb; y++) {
 495             int block_h = s->blocks[block].h;
 496             uint32_t *rect = dst;
 497
 498             for (x = 0; x < s->xb; x++) {
 499                 int block_w = s->blocks[block].w;
 500                 uint32_t *row = dst;
 501
 502                 block_h = s->blocks[block].h;
 503                 if (s->blocks[block].xor) {
 504                     for (k = 0; k < block_h; k++) {
 505                         uint32_t *column = dst;
 506                         for (l = 0; l < block_w; l++)
 507                             *dst++ ^= *src++;
 508                         dst = &column[s->stride];
 509                     }
 510                 }
 511                 dst = &row[block_w];
 512                 ++block;
 513             }
 514             dst = &rect[block_h * s->stride];
 515         }
 516
 517         ssrc = s->buffer;
 518         ddst = frame->data[0] + (avctx->height - 1) * frame->linesize[0];
 519         for (y = 0; y < avctx->height; y++) {
 520             memcpy(ddst, ssrc, avctx->width * s->bpp);
 521             ddst -= frame->linesize[0];
 522             ssrc += s->stride * 4;
 523         }
 524     }
 525
 526     *got_frame = 1;
 527
 528     return avpkt->size;
 529 }
 530
 531 static av_cold int decode_init(AVCodecContext *avctx)
 532 {
 533     FMVCContext *s = avctx->priv_data;
 534     int i, j, m, block = 0, h = BLOCK_HEIGHT, w = BLOCK_WIDTH;
 535
 536     switch (avctx->bits_per_coded_sample) {
 537     case 16:
 538         avctx->pix_fmt = AV_PIX_FMT_RGB555LE;
 539         break;
 540     case 24:
 541         avctx->pix_fmt = AV_PIX_FMT_BGR24;
 542         break;
 543     case 32:
 544         avctx->pix_fmt = AV_PIX_FMT_BGRA;
 545         break;
 546     default:
 547         av_log(avctx, AV_LOG_ERROR, "Unsupported bitdepth %i\n",
 548                avctx->bits_per_coded_sample);
 549         return AVERROR_INVALIDDATA;
 550     }
 551
 552     s->stride = (avctx->width * avctx->bits_per_coded_sample + 31) / 32;
 553     s->xb     = s->stride / BLOCK_WIDTH;
 554     m         = s->stride % BLOCK_WIDTH;
 555     if (m) {
 556         if (m < 37) {
 557             w = m + BLOCK_WIDTH;
 558         } else {
 559             w = m;
 560             s->xb++;
 561         }
 562     }
 563
 564     s->yb = avctx->height / BLOCK_HEIGHT;
 565     m     = avctx->height % BLOCK_HEIGHT;
 566     if (m) {
 567         if (m < 49) {
 568             h = m + BLOCK_HEIGHT;
 569         } else {
 570             h = m;
 571             s->yb++;
 572         }
 573     }
 574
 575     s->nb_blocks = s->xb * s->yb;
 576     if (!s->nb_blocks)
 577         return AVERROR_INVALIDDATA;
 578     s->blocks    = av_calloc(s->nb_blocks, sizeof(*s->blocks));
 579     if (!s->blocks)
 580         return AVERROR(ENOMEM);
 581
 582     for (i = 0; i < s->yb; i++) {
 583         for (j = 0; j < s->xb; j++) {
 584             if (i != (s->yb - 1) || j != (s->xb - 1)) {
 585                 if (i == s->yb - 1) {
 586                     s->blocks[block].w    = BLOCK_WIDTH;
 587                     s->blocks[block].h    = h;
 588                     s->blocks[block].size = BLOCK_WIDTH * h;
 589                 } else if (j == s->xb - 1) {
 590                     s->blocks[block].w    = w;
 591                     s->blocks[block].h    = BLOCK_HEIGHT;
 592                     s->blocks[block].size = BLOCK_HEIGHT * w;
 593                 } else {
 594                     s->blocks[block].w    = BLOCK_WIDTH;
 595                     s->blocks[block].h    = BLOCK_HEIGHT;
 596                     s->blocks[block].size = BLOCK_WIDTH * BLOCK_HEIGHT;
 597                 }
 598             } else {
 599                 s->blocks[block].w    = w;
 600                 s->blocks[block].h    = h;
 601                 s->blocks[block].size = w * h;
 602             }
 603             block++;
 604         }
 605     }
 606
 607     s->bpp          = avctx->bits_per_coded_sample >> 3;
 608     s->buffer_size  = avctx->width * avctx->height * 4;
 609     s->pbuffer_size = avctx->width * avctx->height * 4;
 610     s->buffer       = av_mallocz(s->buffer_size);
 611     s->pbuffer      = av_mallocz(s->pbuffer_size);
 612     if (!s->buffer || !s->pbuffer)
 613         return AVERROR(ENOMEM);
 614
 615     return 0;
 616 }
 617
 618 static av_cold int decode_close(AVCodecContext *avctx)
 619 {
 620     FMVCContext *s = avctx->priv_data;
 621
 622     av_freep(&s->buffer);
 623     av_freep(&s->pbuffer);
 624     av_freep(&s->blocks);
 625
 626     return 0;
 627 }
 628
 629 const AVCodec ff_fmvc_decoder = {
 630     .name             = "fmvc",
 631     .long_name        = NULL_IF_CONFIG_SMALL("FM Screen Capture Codec"),
 632     .type             = AVMEDIA_TYPE_VIDEO,
 633     .id               = AV_CODEC_ID_FMVC,
 634     .priv_data_size   = sizeof(FMVCContext),
 635     .init             = decode_init,
 636     .close            = decode_close,
 637     .decode           = decode_frame,
 638     .capabilities     = AV_CODEC_CAP_DR1,
 639     .caps_internal    = FF_CODEC_CAP_INIT_THREADSAFE |
 640                         FF_CODEC_CAP_INIT_CLEANUP,
 641 };