dpvsimpledecode.c

   1
   2 #include "quakedef.h"
   3 #include "dpvsimpledecode.h"
   4
   5 #define HZREADERROR_OK 0
   6 #define HZREADERROR_EOF 1
   7 #define HZREADERROR_MALLOCFAILED 2
   8
   9 #define HZREADBLOCKSIZE 16000
  10
  11 typedef struct
  12 {
  13         qfile_t *file;
  14         int endoffile;
  15 }
  16 hz_bitstream_read_t;
  17
  18 typedef struct hz_bitstream_readblock_s
  19 {
  20         struct hz_bitstream_readblock_s *next;
  21         unsigned int size;
  22         unsigned char data[HZREADBLOCKSIZE];
  23 }
  24 hz_bitstream_readblock_t;
  25
  26 typedef struct
  27 {
  28         hz_bitstream_readblock_t *blocks;
  29         hz_bitstream_readblock_t *current;
  30         unsigned int position;
  31         unsigned int store;
  32         int count;
  33 }
  34 hz_bitstream_readblocks_t;
  35
  36 hz_bitstream_read_t *hz_bitstream_read_open(char *filename)
  37 {
  38         qfile_t *file;
  39         hz_bitstream_read_t *stream;
  40         if ((file = FS_Open (filename, "rb", false)))
  41         {
  42                 stream = malloc(sizeof(hz_bitstream_read_t));
  43                 memset(stream, 0, sizeof(*stream));
  44                 stream->file = file;
  45                 return stream;
  46         }
  47         else
  48                 return NULL;
  49 }
  50
  51 void hz_bitstream_read_close(hz_bitstream_read_t *stream)
  52 {
  53         if (stream)
  54         {
  55                 FS_Close(stream->file);
  56                 free(stream);
  57         }
  58 }
  59
  60 hz_bitstream_readblocks_t *hz_bitstream_read_blocks_new(void)
  61 {
  62         hz_bitstream_readblocks_t *blocks;
  63         blocks = malloc(sizeof(hz_bitstream_readblocks_t));
  64         if (blocks == NULL)
  65                 return NULL;
  66         memset(blocks, 0, sizeof(hz_bitstream_readblocks_t));
  67         return blocks;
  68 }
  69
  70 void hz_bitstream_read_blocks_free(hz_bitstream_readblocks_t *blocks)
  71 {
  72         hz_bitstream_readblock_t *b, *n;
  73         if (blocks == NULL)
  74                 return;
  75         for (b = blocks->blocks;b;b = n)
  76         {
  77                 n = b->next;
  78                 free(b);
  79         }
  80         free(blocks);
  81 }
  82
  83 void hz_bitstream_read_flushbits(hz_bitstream_readblocks_t *blocks)
  84 {
  85         blocks->store = 0;
  86         blocks->count = 0;
  87 }
  88
  89 int hz_bitstream_read_blocks_read(hz_bitstream_readblocks_t *blocks, hz_bitstream_read_t *stream, unsigned int size)
  90 {
  91         int s;
  92         hz_bitstream_readblock_t *b, *p;
  93         s = size;
  94         p = NULL;
  95         b = blocks->blocks;
  96         while (s > 0)
  97         {
  98                 if (b == NULL)
  99                 {
 100                         b = malloc(sizeof(hz_bitstream_readblock_t));
 101                         if (b == NULL)
 102                                 return HZREADERROR_MALLOCFAILED;
 103                         b->next = NULL;
 104                         b->size = 0;
 105                         if (p != NULL)
 106                                 p->next = b;
 107                         else
 108                                 blocks->blocks = b;
 109                 }
 110                 if (s > HZREADBLOCKSIZE)
 111                         b->size = HZREADBLOCKSIZE;
 112                 else
 113                         b->size = s;
 114                 s -= b->size;
 115                 if (FS_Read(stream->file, b->data, b->size) != b->size)
 116                 {
 117                         stream->endoffile = 1;
 118                         break;
 119                 }
 120                 p = b;
 121                 b = b->next;
 122         }
 123         while (b)
 124         {
 125                 b->size = 0;
 126                 b = b->next;
 127         }
 128         blocks->current = blocks->blocks;
 129         blocks->position = 0;
 130         hz_bitstream_read_flushbits(blocks);
 131         if (stream->endoffile)
 132                 return HZREADERROR_EOF;
 133         return HZREADERROR_OK;
 134 }
 135
 136 unsigned int hz_bitstream_read_blocks_getbyte(hz_bitstream_readblocks_t *blocks)
 137 {
 138         while (blocks->current != NULL && blocks->position >= blocks->current->size)
 139         {
 140                 blocks->position = 0;
 141                 blocks->current = blocks->current->next;
 142         }
 143         if (blocks->current == NULL)
 144                 return 0;
 145         return blocks->current->data[blocks->position++];
 146 }
 147
 148 int hz_bitstream_read_bit(hz_bitstream_readblocks_t *blocks)
 149 {
 150         if (!blocks->count)
 151         {
 152                 blocks->count += 8;
 153                 blocks->store <<= 8;
 154                 blocks->store |= hz_bitstream_read_blocks_getbyte(blocks) & 0xFF;
 155         }
 156         blocks->count--;
 157         return (blocks->store >> blocks->count) & 1;
 158 }
 159
 160 unsigned int hz_bitstream_read_bits(hz_bitstream_readblocks_t *blocks, int size)
 161 {
 162         unsigned int num = 0;
 163         // we can only handle about 24 bits at a time safely
 164         // (there might be up to 7 bits more than we need in the bit store)
 165         if (size > 24)
 166         {
 167                 size -= 8;
 168                 num |= hz_bitstream_read_bits(blocks, 8) << size;
 169         }
 170         while (blocks->count < size)
 171         {
 172                 blocks->count += 8;
 173                 blocks->store <<= 8;
 174                 blocks->store |= hz_bitstream_read_blocks_getbyte(blocks) & 0xFF;
 175         }
 176         blocks->count -= size;
 177         num |= (blocks->store >> blocks->count) & ((1 << size) - 1);
 178         return num;
 179 }
 180
 181 unsigned int hz_bitstream_read_byte(hz_bitstream_readblocks_t *blocks)
 182 {
 183         return hz_bitstream_read_blocks_getbyte(blocks);
 184 }
 185
 186 unsigned int hz_bitstream_read_short(hz_bitstream_readblocks_t *blocks)
 187 {
 188         return (hz_bitstream_read_byte(blocks) << 8)
 189              | (hz_bitstream_read_byte(blocks));
 190 }
 191
 192 unsigned int hz_bitstream_read_int(hz_bitstream_readblocks_t *blocks)
 193 {
 194         return (hz_bitstream_read_byte(blocks) << 24)
 195              | (hz_bitstream_read_byte(blocks) << 16)
 196              | (hz_bitstream_read_byte(blocks) << 8)
 197              | (hz_bitstream_read_byte(blocks));
 198 }
 199
 200 void hz_bitstream_read_bytes(hz_bitstream_readblocks_t *blocks, void *outdata, unsigned int size)
 201 {
 202         unsigned char *out;
 203         out = outdata;
 204         while (size--)
 205                 *out++ = hz_bitstream_read_byte(blocks);
 206 }
 207
 208 #define BLOCKSIZE 8
 209
 210 typedef struct dpvsimpledecodestream_s
 211 {
 212         hz_bitstream_read_t *bitstream;
 213         hz_bitstream_readblocks_t *framedatablocks;
 214
 215         int error;
 216
 217         double info_framerate;
 218         unsigned int info_frames;
 219
 220         unsigned int info_imagewidth;
 221         unsigned int info_imageheight;
 222         unsigned int info_imagebpp;
 223         unsigned int info_imageRloss;
 224         unsigned int info_imageRmask;
 225         unsigned int info_imageRshift;
 226         unsigned int info_imageGloss;
 227         unsigned int info_imageGmask;
 228         unsigned int info_imageGshift;
 229         unsigned int info_imageBloss;
 230         unsigned int info_imageBmask;
 231         unsigned int info_imageBshift;
 232         unsigned int info_imagesize;
 233
 234         // current video frame (needed because of delta compression)
 235         int videoframenum;
 236         // current video frame data (needed because of delta compression)
 237         unsigned int *videopixels;
 238
 239         // channel the sound file is being played on
 240         int sndchan;
 241 }
 242 dpvsimpledecodestream_t;
 243
 244 static int dpvsimpledecode_setpixelformat(dpvsimpledecodestream_t *s, unsigned int Rmask, unsigned int Gmask, unsigned int Bmask, unsigned int bytesperpixel)
 245 {
 246         int Rshift, Rbits, Gshift, Gbits, Bshift, Bbits;
 247         if (!Rmask)
 248         {
 249                 s->error = DPVSIMPLEDECODEERROR_INVALIDRMASK;
 250                 return s->error;
 251         }
 252         if (!Gmask)
 253         {
 254                 s->error = DPVSIMPLEDECODEERROR_INVALIDGMASK;
 255                 return s->error;
 256         }
 257         if (!Bmask)
 258         {
 259                 s->error = DPVSIMPLEDECODEERROR_INVALIDBMASK;
 260                 return s->error;
 261         }
 262         if (Rmask & Gmask || Rmask & Bmask || Gmask & Bmask)
 263         {
 264                 s->error = DPVSIMPLEDECODEERROR_COLORMASKSOVERLAP;
 265                 return s->error;
 266         }
 267         switch (bytesperpixel)
 268         {
 269         case 2:
 270                 if ((Rmask | Gmask | Bmask) > 65536)
 271                 {
 272                         s->error = DPVSIMPLEDECODEERROR_COLORMASKSEXCEEDBPP;
 273                         return s->error;
 274                 }
 275                 break;
 276         case 4:
 277                 break;
 278         default:
 279                 s->error = DPVSIMPLEDECODEERROR_UNSUPPORTEDBPP;
 280                 return s->error;
 281                 break;
 282         }
 283         for (Rshift = 0;!(Rmask & 1);Rshift++, Rmask >>= 1);
 284         for (Gshift = 0;!(Gmask & 1);Gshift++, Gmask >>= 1);
 285         for (Bshift = 0;!(Bmask & 1);Bshift++, Bmask >>= 1);
 286         if (((Rmask + 1) & Rmask) != 0)
 287         {
 288                 s->error = DPVSIMPLEDECODEERROR_INVALIDRMASK;
 289                 return s->error;
 290         }
 291         if (((Gmask + 1) & Gmask) != 0)
 292         {
 293                 s->error = DPVSIMPLEDECODEERROR_INVALIDGMASK;
 294                 return s->error;
 295         }
 296         if (((Bmask + 1) & Bmask) != 0)
 297         {
 298                 s->error = DPVSIMPLEDECODEERROR_INVALIDBMASK;
 299                 return s->error;
 300         }
 301         for (Rbits = 0;Rmask & 1;Rbits++, Rmask >>= 1);
 302         for (Gbits = 0;Gmask & 1;Gbits++, Gmask >>= 1);
 303         for (Bbits = 0;Bmask & 1;Bbits++, Bmask >>= 1);
 304         if (Rbits > 8)
 305         {
 306                 Rshift += (Rbits - 8);
 307                 Rbits = 8;
 308         }
 309         if (Gbits > 8)
 310         {
 311                 Gshift += (Gbits - 8);
 312                 Gbits = 8;
 313         }
 314         if (Bbits > 8)
 315         {
 316                 Bshift += (Bbits - 8);
 317                 Bbits = 8;
 318         }
 319         s->info_imagebpp = bytesperpixel;
 320         s->info_imageRloss = 16 + (8 - Rbits);
 321         s->info_imageGloss =  8 + (8 - Gbits);
 322         s->info_imageBloss =  0 + (8 - Bbits);
 323         s->info_imageRmask = (1 << Rbits) - 1;
 324         s->info_imageGmask = (1 << Gbits) - 1;
 325         s->info_imageBmask = (1 << Bbits) - 1;
 326         s->info_imageRshift = Rshift;
 327         s->info_imageGshift = Gshift;
 328         s->info_imageBshift = Bshift;
 329         s->info_imagesize = s->info_imagewidth * s->info_imageheight * s->info_imagebpp;
 330         return s->error;
 331 }
 332
 333 // opening and closing streams
 334
 335 static void StripExtension(char *in, char *out)
 336 {
 337         char *dot, *c;
 338         dot = NULL;
 339         for (c = in;*c;c++)
 340         {
 341                 if (*c == ':' || *c == '\\' || *c == '/')
 342                         dot = NULL;
 343                 if (*c == '.')
 344                         dot = c;
 345         }
 346         if (dot == NULL)
 347         {
 348                 // nothing to remove
 349                 strcpy(out, in);
 350                 return;
 351         }
 352         else
 353         {
 354                 memcpy(out, in, dot - in);
 355                 out[dot - in] = 0;
 356         }
 357 }
 358
 359 // opens a stream
 360 void *dpvsimpledecode_open(char *filename, char **errorstring)
 361 {
 362         dpvsimpledecodestream_t *s;
 363         char t[8], *wavename;
 364         if (errorstring != NULL)
 365                 *errorstring = NULL;
 366         s = malloc(sizeof(dpvsimpledecodestream_t));
 367         if (s != NULL)
 368         {
 369                 s->bitstream = hz_bitstream_read_open(filename);
 370                 if (s->bitstream != NULL)
 371                 {
 372                         // check file identification
 373                         s->framedatablocks = hz_bitstream_read_blocks_new();
 374                         if (s->framedatablocks != NULL)
 375                         {
 376                                 hz_bitstream_read_blocks_read(s->framedatablocks, s->bitstream, 8);
 377                                 hz_bitstream_read_bytes(s->framedatablocks, t, 8);
 378                                 if (!memcmp(t, "DPVideo", 8))
 379                                 {
 380                                         // check version number
 381                                         hz_bitstream_read_blocks_read(s->framedatablocks, s->bitstream, 2);
 382                                         if (hz_bitstream_read_short(s->framedatablocks) == 1)
 383                                         {
 384                                                 hz_bitstream_read_blocks_read(s->framedatablocks, s->bitstream, 12);
 385                                                 s->info_imagewidth = hz_bitstream_read_short(s->framedatablocks);
 386                                                 s->info_imageheight = hz_bitstream_read_short(s->framedatablocks);
 387                                                 s->info_framerate = (double) hz_bitstream_read_int(s->framedatablocks) * (1.0 / 65536.0);
 388
 389                                                 if (s->info_framerate > 0.0)
 390                                                 {
 391                                                         s->videopixels = malloc(s->info_imagewidth * s->info_imageheight * sizeof(*s->videopixels));
 392                                                         if (s->videopixels != NULL)
 393                                                         {
 394                                                                 wavename = malloc(strlen(filename) + 10);
 395                                                                 if (wavename)
 396                                                                 {
 397                                                                         sfx_t* sfx;
 398
 399                                                                         StripExtension(filename, wavename);
 400                                                                         strcat(wavename, ".wav");
 401                                                                         sfx = S_PrecacheSound (wavename, false, false);
 402                                                                         if (sfx != NULL)
 403                                                                                 s->sndchan = S_StartSound (-1, 0, sfx, vec3_origin, 1.0f, 0);
 404                                                                         else
 405                                                                                 s->sndchan = -1;
 406                                                                         free(wavename);
 407                                                                 }
 408                                                                 // all is well...
 409                                                                 s->videoframenum = -10000;
 410                                                                 return s;
 411                                                         }
 412                                                         else if (errorstring != NULL)
 413                                                                 *errorstring = "unable to allocate video image buffer";
 414                                                 }
 415                                                 else if (errorstring != NULL)
 416                                                         *errorstring = "error in video info chunk";
 417                                         }
 418                                         else if (errorstring != NULL)
 419                                                 *errorstring = "read error";
 420                                 }
 421                                 else if (errorstring != NULL)
 422                                         *errorstring = "not a dpvideo file";
 423                                 hz_bitstream_read_blocks_free(s->framedatablocks);
 424                         }
 425                         else if (errorstring != NULL)
 426                                 *errorstring = "unable to allocate memory for reading buffer";
 427                         hz_bitstream_read_close(s->bitstream);
 428                 }
 429                 else if (errorstring != NULL)
 430                         *errorstring = "unable to open file";
 431                 free(s);
 432         }
 433         else if (errorstring != NULL)
 434                 *errorstring = "unable to allocate memory for stream info structure";
 435         return NULL;
 436 }
 437
 438 // closes a stream
 439 void dpvsimpledecode_close(void *stream)
 440 {
 441         dpvsimpledecodestream_t *s = stream;
 442         if (s == NULL)
 443                 return;
 444         if (s->videopixels)
 445                 free(s->videopixels);
 446         if (s->sndchan != -1)
 447                 S_StopChannel (s->sndchan);
 448         if (s->framedatablocks)
 449                 hz_bitstream_read_blocks_free(s->framedatablocks);
 450         if (s->bitstream)
 451                 hz_bitstream_read_close(s->bitstream);
 452         free(s);
 453 }
 454
 455 // utilitarian functions
 456
 457 // returns the current error number for the stream, and resets the error
 458 // number to DPVSIMPLEDECODEERROR_NONE
 459 // if the supplied string pointer variable is not NULL, it will be set to the
 460 // error message
 461 int dpvsimpledecode_error(void *stream, char **errorstring)
 462 {
 463         dpvsimpledecodestream_t *s = stream;
 464         int e;
 465         e = s->error;
 466         s->error = 0;
 467         if (errorstring)
 468         {
 469                 switch (e)
 470                 {
 471                         case DPVSIMPLEDECODEERROR_NONE:
 472                                 *errorstring = "no error";
 473                                 break;
 474                         case DPVSIMPLEDECODEERROR_EOF:
 475                                 *errorstring = "end of file reached (this is not an error)";
 476                                 break;
 477                         case DPVSIMPLEDECODEERROR_READERROR:
 478                                 *errorstring = "read error (corrupt or incomplete file)";
 479                                 break;
 480                         case DPVSIMPLEDECODEERROR_SOUNDBUFFERTOOSMALL:
 481                                 *errorstring = "sound buffer is too small for decoding frame (please allocate it as large as dpvsimpledecode_getneededsoundbufferlength suggests)";
 482                                 break;
 483                         case DPVSIMPLEDECODEERROR_INVALIDRMASK:
 484                                 *errorstring = "invalid red bits mask";
 485                                 break;
 486                         case DPVSIMPLEDECODEERROR_INVALIDGMASK:
 487                                 *errorstring = "invalid green bits mask";
 488                                 break;
 489                         case DPVSIMPLEDECODEERROR_INVALIDBMASK:
 490                                 *errorstring = "invalid blue bits mask";
 491                                 break;
 492                         case DPVSIMPLEDECODEERROR_COLORMASKSOVERLAP:
 493                                 *errorstring = "color bit masks overlap";
 494                                 break;
 495                         case DPVSIMPLEDECODEERROR_COLORMASKSEXCEEDBPP:
 496                                 *errorstring = "color masks too big for specified bytes per pixel";
 497                                 break;
 498                         case DPVSIMPLEDECODEERROR_UNSUPPORTEDBPP:
 499                                 *errorstring = "unsupported bytes per pixel (must be 2 for 16bit, or 4 for 32bit)";
 500                                 break;
 501                         default:
 502                                 *errorstring = "unknown error";
 503                                 break;
 504                 }
 505         }
 506         return e;
 507 }
 508
 509 // returns the width of the image data
 510 unsigned int dpvsimpledecode_getwidth(void *stream)
 511 {
 512         dpvsimpledecodestream_t *s = stream;
 513         return s->info_imagewidth;
 514 }
 515
 516 // returns the height of the image data
 517 unsigned int dpvsimpledecode_getheight(void *stream)
 518 {
 519         dpvsimpledecodestream_t *s = stream;
 520         return s->info_imageheight;
 521 }
 522
 523 // returns the framerate of the stream
 524 double dpvsimpledecode_getframerate(void *stream)
 525 {
 526         dpvsimpledecodestream_t *s = stream;
 527         return s->info_framerate;
 528 }
 529
 530
 531
 532
 533
 534 static int dpvsimpledecode_convertpixels(dpvsimpledecodestream_t *s, void *imagedata, int imagebytesperrow)
 535 {
 536         unsigned int a, x, y, width, height;
 537         unsigned int Rloss, Rmask, Rshift, Gloss, Gmask, Gshift, Bloss, Bmask, Bshift;
 538         unsigned int *in;
 539
 540         width = s->info_imagewidth;
 541         height = s->info_imageheight;
 542
 543         Rloss = s->info_imageRloss;
 544         Rmask = s->info_imageRmask;
 545         Rshift = s->info_imageRshift;
 546         Gloss = s->info_imageGloss;
 547         Gmask = s->info_imageGmask;
 548         Gshift = s->info_imageGshift;
 549         Bloss = s->info_imageBloss;
 550         Bmask = s->info_imageBmask;
 551         Bshift = s->info_imageBshift;
 552
 553         in = s->videopixels;
 554         if (s->info_imagebpp == 4)
 555         {
 556                 unsigned int *outrow;
 557                 for (y = 0;y < height;y++)
 558                 {
 559                         outrow = (void *)((unsigned char *)imagedata + y * imagebytesperrow);
 560                         for (x = 0;x < width;x++)
 561                         {
 562                                 a = *in++;
 563                                 outrow[x] = (((a >> Rloss) & Rmask) << Rshift) | (((a >> Gloss) & Gmask) << Gshift) | (((a >> Bloss) & Bmask) << Bshift);
 564                         }
 565                 }
 566         }
 567         else
 568         {
 569                 unsigned short *outrow;
 570                 for (y = 0;y < height;y++)
 571                 {
 572                         outrow = (void *)((unsigned char *)imagedata + y * imagebytesperrow);
 573                         if (Rloss == 19 && Gloss == 10 && Bloss == 3 && Rshift == 11 && Gshift == 5 && Bshift == 0)
 574                         {
 575                                 // optimized
 576                                 for (x = 0;x < width;x++)
 577                                 {
 578                                         a = *in++;
 579                                         outrow[x] = ((a >> 8) & 0xF800) | ((a >> 5) & 0x07E0) | ((a >> 3) & 0x001F);
 580                                 }
 581                         }
 582                         else
 583                         {
 584                                 for (x = 0;x < width;x++)
 585                                 {
 586                                         a = *in++;
 587                                         outrow[x] = (((a >> Rloss) & Rmask) << Rshift) | (((a >> Gloss) & Gmask) << Gshift) | (((a >> Bloss) & Bmask) << Bshift);
 588                                 }
 589                         }
 590                 }
 591         }
 592         return s->error;
 593 }
 594
 595 static int dpvsimpledecode_decompressimage(dpvsimpledecodestream_t *s)
 596 {
 597         int i, a, b, colors, g, x1, y1, bw, bh, width, height, palettebits;
 598         unsigned int palette[256], *outrow, *out;
 599         g = BLOCKSIZE;
 600         width = s->info_imagewidth;
 601         height = s->info_imageheight;
 602         for (y1 = 0;y1 < height;y1 += g)
 603         {
 604                 outrow = s->videopixels + y1 * width;
 605                 bh = g;
 606                 if (y1 + bh > height)
 607                         bh = height - y1;
 608                 for (x1 = 0;x1 < width;x1 += g)
 609                 {
 610                         out = outrow + x1;
 611                         bw = g;
 612                         if (x1 + bw > width)
 613                                 bw = width - x1;
 614                         if (hz_bitstream_read_bit(s->framedatablocks))
 615                         {
 616                                 // updated block
 617                                 palettebits = hz_bitstream_read_bits(s->framedatablocks, 3);
 618                                 colors = 1 << palettebits;
 619                                 for (i = 0;i < colors;i++)
 620                                         palette[i] = hz_bitstream_read_bits(s->framedatablocks, 24);
 621                                 if (palettebits)
 622                                 {
 623                                         for (b = 0;b < bh;b++, out += width)
 624                                                 for (a = 0;a < bw;a++)
 625                                                         out[a] = palette[hz_bitstream_read_bits(s->framedatablocks, palettebits)];
 626                                 }
 627                                 else
 628                                 {
 629                                         for (b = 0;b < bh;b++, out += width)
 630                                                 for (a = 0;a < bw;a++)
 631                                                         out[a] = palette[0];
 632                                 }
 633                         }
 634                 }
 635         }
 636         return s->error;
 637 }
 638
 639 // decodes a video frame to the supplied output pixels
 640 int dpvsimpledecode_video(void *stream, void *imagedata, unsigned int Rmask, unsigned int Gmask, unsigned int Bmask, unsigned int bytesperpixel, int imagebytesperrow)
 641 {
 642         dpvsimpledecodestream_t *s = stream;
 643         unsigned int framedatasize;
 644         char t[4];
 645         s->error = DPVSIMPLEDECODEERROR_NONE;
 646         if (dpvsimpledecode_setpixelformat(s, Rmask, Gmask, Bmask, bytesperpixel))
 647                 return s->error;
 648
 649         hz_bitstream_read_blocks_read(s->framedatablocks, s->bitstream, 8);
 650         hz_bitstream_read_bytes(s->framedatablocks, t, 4);
 651         if (memcmp(t, "VID0", 4))
 652         {
 653                 if (t[0] == 0)
 654                         return (s->error = DPVSIMPLEDECODEERROR_EOF);
 655                 else
 656                         return (s->error = DPVSIMPLEDECODEERROR_READERROR);
 657         }
 658         framedatasize = hz_bitstream_read_int(s->framedatablocks);
 659         hz_bitstream_read_blocks_read(s->framedatablocks, s->bitstream, framedatasize);
 660         if (dpvsimpledecode_decompressimage(s))
 661                 return s->error;
 662
 663         dpvsimpledecode_convertpixels(s, imagedata, imagebytesperrow);
 664         return s->error;
 665 }