jcmarker.c (16527B)
1 /* 2 * jcmarker.c 3 * 4 * Copyright (C) 1991-1995, Thomas G. Lane. 5 * This file is part of the Independent JPEG Group's software. 6 * For conditions of distribution and use, see the accompanying README file. 7 * 8 * This file contains routines to write JPEG datastream markers. 9 */ 10 11 #define JPEG_INTERNALS 12 #include "jinclude.h" 13 #include "jpeglib.h" 14 15 16 typedef enum { /* JPEG marker codes */ 17 M_SOF0 = 0xc0, 18 M_SOF1 = 0xc1, 19 M_SOF2 = 0xc2, 20 M_SOF3 = 0xc3, 21 22 M_SOF5 = 0xc5, 23 M_SOF6 = 0xc6, 24 M_SOF7 = 0xc7, 25 26 M_JPG = 0xc8, 27 M_SOF9 = 0xc9, 28 M_SOF10 = 0xca, 29 M_SOF11 = 0xcb, 30 31 M_SOF13 = 0xcd, 32 M_SOF14 = 0xce, 33 M_SOF15 = 0xcf, 34 35 M_DHT = 0xc4, 36 37 M_DAC = 0xcc, 38 39 M_RST0 = 0xd0, 40 M_RST1 = 0xd1, 41 M_RST2 = 0xd2, 42 M_RST3 = 0xd3, 43 M_RST4 = 0xd4, 44 M_RST5 = 0xd5, 45 M_RST6 = 0xd6, 46 M_RST7 = 0xd7, 47 48 M_SOI = 0xd8, 49 M_EOI = 0xd9, 50 M_SOS = 0xda, 51 M_DQT = 0xdb, 52 M_DNL = 0xdc, 53 M_DRI = 0xdd, 54 M_DHP = 0xde, 55 M_EXP = 0xdf, 56 57 M_APP0 = 0xe0, 58 M_APP1 = 0xe1, 59 M_APP2 = 0xe2, 60 M_APP3 = 0xe3, 61 M_APP4 = 0xe4, 62 M_APP5 = 0xe5, 63 M_APP6 = 0xe6, 64 M_APP7 = 0xe7, 65 M_APP8 = 0xe8, 66 M_APP9 = 0xe9, 67 M_APP10 = 0xea, 68 M_APP11 = 0xeb, 69 M_APP12 = 0xec, 70 M_APP13 = 0xed, 71 M_APP14 = 0xee, 72 M_APP15 = 0xef, 73 74 M_JPG0 = 0xf0, 75 M_JPG13 = 0xfd, 76 M_COM = 0xfe, 77 78 M_TEM = 0x01, 79 80 M_ERROR = 0x100 81 } JPEG_MARKER; 82 83 84 /* 85 * Basic output routines. 86 * 87 * Note that we do not support suspension while writing a marker. 88 * Therefore, an application using suspension must ensure that there is 89 * enough buffer space for the initial markers (typ. 600-700 bytes) before 90 * calling jpeg_start_compress, and enough space to write the trailing EOI 91 * (a few bytes) before calling jpeg_finish_compress. Multipass compression 92 * modes are not supported at all with suspension, so those two are the only 93 * points where markers will be written. 94 */ 95 96 LOCAL void 97 emit_byte (j_compress_ptr cinfo, int val) 98 /* Emit a byte */ 99 { 100 struct jpeg_destination_mgr * dest = cinfo->dest; 101 102 *(dest->next_output_byte)++ = (JOCTET) val; 103 if (--dest->free_in_buffer == 0) { 104 if (! (*dest->empty_output_buffer) (cinfo)) 105 ERREXIT(cinfo, JERR_CANT_SUSPEND); 106 } 107 } 108 109 110 LOCAL void 111 emit_marker (j_compress_ptr cinfo, JPEG_MARKER mark) 112 /* Emit a marker code */ 113 { 114 emit_byte(cinfo, 0xFF); 115 emit_byte(cinfo, (int) mark); 116 } 117 118 119 LOCAL void 120 emit_2bytes (j_compress_ptr cinfo, int value) 121 /* Emit a 2-byte integer; these are always MSB first in JPEG files */ 122 { 123 emit_byte(cinfo, (value >> 8) & 0xFF); 124 emit_byte(cinfo, value & 0xFF); 125 } 126 127 128 /* 129 * Routines to write specific marker types. 130 */ 131 132 LOCAL int 133 emit_dqt (j_compress_ptr cinfo, int index) 134 /* Emit a DQT marker */ 135 /* Returns the precision used (0 = 8bits, 1 = 16bits) for baseline checking */ 136 { 137 JQUANT_TBL * qtbl = cinfo->quant_tbl_ptrs[index]; 138 int prec; 139 int i; 140 141 if (qtbl == NULL) 142 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, index); 143 144 prec = 0; 145 for (i = 0; i < DCTSIZE2; i++) { 146 if (qtbl->quantval[i] > 255) 147 prec = 1; 148 } 149 150 if (! qtbl->sent_table) { 151 emit_marker(cinfo, M_DQT); 152 153 emit_2bytes(cinfo, prec ? DCTSIZE2*2 + 1 + 2 : DCTSIZE2 + 1 + 2); 154 155 emit_byte(cinfo, index + (prec<<4)); 156 157 for (i = 0; i < DCTSIZE2; i++) { 158 if (prec) 159 emit_byte(cinfo, qtbl->quantval[i] >> 8); 160 emit_byte(cinfo, qtbl->quantval[i] & 0xFF); 161 } 162 163 qtbl->sent_table = TRUE; 164 } 165 166 return prec; 167 } 168 169 170 LOCAL void 171 emit_dht (j_compress_ptr cinfo, int index, boolean is_ac) 172 /* Emit a DHT marker */ 173 { 174 JHUFF_TBL * htbl; 175 int length, i; 176 177 if (is_ac) { 178 htbl = cinfo->ac_huff_tbl_ptrs[index]; 179 index += 0x10; /* output index has AC bit set */ 180 } else { 181 htbl = cinfo->dc_huff_tbl_ptrs[index]; 182 } 183 184 if (htbl == NULL) 185 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, index); 186 187 if (! htbl->sent_table) { 188 emit_marker(cinfo, M_DHT); 189 190 length = 0; 191 for (i = 1; i <= 16; i++) 192 length += htbl->bits[i]; 193 194 emit_2bytes(cinfo, length + 2 + 1 + 16); 195 emit_byte(cinfo, index); 196 197 for (i = 1; i <= 16; i++) 198 emit_byte(cinfo, htbl->bits[i]); 199 200 for (i = 0; i < length; i++) 201 emit_byte(cinfo, htbl->huffval[i]); 202 203 htbl->sent_table = TRUE; 204 } 205 } 206 207 208 LOCAL void 209 emit_dac (j_compress_ptr cinfo) 210 /* Emit a DAC marker */ 211 /* Since the useful info is so small, we want to emit all the tables in */ 212 /* one DAC marker. Therefore this routine does its own scan of the table. */ 213 { 214 #ifdef C_ARITH_CODING_SUPPORTED 215 char dc_in_use[NUM_ARITH_TBLS]; 216 char ac_in_use[NUM_ARITH_TBLS]; 217 int length, i; 218 jpeg_component_info *compptr; 219 220 for (i = 0; i < NUM_ARITH_TBLS; i++) 221 dc_in_use[i] = ac_in_use[i] = 0; 222 223 for (i = 0; i < cinfo->comps_in_scan; i++) { 224 compptr = cinfo->cur_comp_info[i]; 225 dc_in_use[compptr->dc_tbl_no] = 1; 226 ac_in_use[compptr->ac_tbl_no] = 1; 227 } 228 229 length = 0; 230 for (i = 0; i < NUM_ARITH_TBLS; i++) 231 length += dc_in_use[i] + ac_in_use[i]; 232 233 emit_marker(cinfo, M_DAC); 234 235 emit_2bytes(cinfo, length*2 + 2); 236 237 for (i = 0; i < NUM_ARITH_TBLS; i++) { 238 if (dc_in_use[i]) { 239 emit_byte(cinfo, i); 240 emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4)); 241 } 242 if (ac_in_use[i]) { 243 emit_byte(cinfo, i + 0x10); 244 emit_byte(cinfo, cinfo->arith_ac_K[i]); 245 } 246 } 247 #endif /* C_ARITH_CODING_SUPPORTED */ 248 } 249 250 251 LOCAL void 252 emit_dri (j_compress_ptr cinfo) 253 /* Emit a DRI marker */ 254 { 255 emit_marker(cinfo, M_DRI); 256 257 emit_2bytes(cinfo, 4); /* fixed length */ 258 259 emit_2bytes(cinfo, (int) cinfo->restart_interval); 260 } 261 262 263 LOCAL void 264 emit_sof (j_compress_ptr cinfo, JPEG_MARKER code) 265 /* Emit a SOF marker */ 266 { 267 int ci; 268 jpeg_component_info *compptr; 269 270 emit_marker(cinfo, code); 271 272 emit_2bytes(cinfo, 3 * cinfo->num_components + 2 + 5 + 1); /* length */ 273 274 /* Make sure image isn't bigger than SOF field can handle */ 275 if ((long) cinfo->image_height > 65535L || 276 (long) cinfo->image_width > 65535L) 277 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) 65535); 278 279 emit_byte(cinfo, cinfo->data_precision); 280 emit_2bytes(cinfo, (int) cinfo->image_height); 281 emit_2bytes(cinfo, (int) cinfo->image_width); 282 283 emit_byte(cinfo, cinfo->num_components); 284 285 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 286 ci++, compptr++) { 287 emit_byte(cinfo, compptr->component_id); 288 emit_byte(cinfo, (compptr->h_samp_factor << 4) + compptr->v_samp_factor); 289 emit_byte(cinfo, compptr->quant_tbl_no); 290 } 291 } 292 293 294 LOCAL void 295 emit_sos (j_compress_ptr cinfo) 296 /* Emit a SOS marker */ 297 { 298 int i, td, ta; 299 jpeg_component_info *compptr; 300 301 emit_marker(cinfo, M_SOS); 302 303 emit_2bytes(cinfo, 2 * cinfo->comps_in_scan + 2 + 1 + 3); /* length */ 304 305 emit_byte(cinfo, cinfo->comps_in_scan); 306 307 for (i = 0; i < cinfo->comps_in_scan; i++) { 308 compptr = cinfo->cur_comp_info[i]; 309 emit_byte(cinfo, compptr->component_id); 310 td = compptr->dc_tbl_no; 311 ta = compptr->ac_tbl_no; 312 if (cinfo->progressive_mode) { 313 /* Progressive mode: only DC or only AC tables are used in one scan; 314 * furthermore, Huffman coding of DC refinement uses no table at all. 315 * We emit 0 for unused field(s); this is recommended by the P&M text 316 * but does not seem to be specified in the standard. 317 */ 318 if (cinfo->Ss == 0) { 319 ta = 0; /* DC scan */ 320 if (cinfo->Ah != 0 && !cinfo->arith_code) 321 td = 0; /* no DC table either */ 322 } else { 323 td = 0; /* AC scan */ 324 } 325 } 326 emit_byte(cinfo, (td << 4) + ta); 327 } 328 329 emit_byte(cinfo, cinfo->Ss); 330 emit_byte(cinfo, cinfo->Se); 331 emit_byte(cinfo, (cinfo->Ah << 4) + cinfo->Al); 332 } 333 334 335 LOCAL void 336 emit_jfif_app0 (j_compress_ptr cinfo) 337 /* Emit a JFIF-compliant APP0 marker */ 338 { 339 /* 340 * Length of APP0 block (2 bytes) 341 * Block ID (4 bytes - ASCII "JFIF") 342 * Zero byte (1 byte to terminate the ID string) 343 * Version Major, Minor (2 bytes - 0x01, 0x01) 344 * Units (1 byte - 0x00 = none, 0x01 = inch, 0x02 = cm) 345 * Xdpu (2 bytes - dots per unit horizontal) 346 * Ydpu (2 bytes - dots per unit vertical) 347 * Thumbnail X size (1 byte) 348 * Thumbnail Y size (1 byte) 349 */ 350 351 emit_marker(cinfo, M_APP0); 352 353 emit_2bytes(cinfo, 2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1); /* length */ 354 355 emit_byte(cinfo, 0x4A); /* Identifier: ASCII "JFIF" */ 356 emit_byte(cinfo, 0x46); 357 emit_byte(cinfo, 0x49); 358 emit_byte(cinfo, 0x46); 359 emit_byte(cinfo, 0); 360 /* We currently emit version code 1.01 since we use no 1.02 features. 361 * This may avoid complaints from some older decoders. 362 */ 363 emit_byte(cinfo, 1); /* Major version */ 364 emit_byte(cinfo, 1); /* Minor version */ 365 emit_byte(cinfo, cinfo->density_unit); /* Pixel size information */ 366 emit_2bytes(cinfo, (int) cinfo->X_density); 367 emit_2bytes(cinfo, (int) cinfo->Y_density); 368 emit_byte(cinfo, 0); /* No thumbnail image */ 369 emit_byte(cinfo, 0); 370 } 371 372 373 LOCAL void 374 emit_adobe_app14 (j_compress_ptr cinfo) 375 /* Emit an Adobe APP14 marker */ 376 { 377 /* 378 * Length of APP14 block (2 bytes) 379 * Block ID (5 bytes - ASCII "Adobe") 380 * Version Number (2 bytes - currently 100) 381 * Flags0 (2 bytes - currently 0) 382 * Flags1 (2 bytes - currently 0) 383 * Color transform (1 byte) 384 * 385 * Although Adobe TN 5116 mentions Version = 101, all the Adobe files 386 * now in circulation seem to use Version = 100, so that's what we write. 387 * 388 * We write the color transform byte as 1 if the JPEG color space is 389 * YCbCr, 2 if it's YCCK, 0 otherwise. Adobe's definition has to do with 390 * whether the encoder performed a transformation, which is pretty useless. 391 */ 392 393 emit_marker(cinfo, M_APP14); 394 395 emit_2bytes(cinfo, 2 + 5 + 2 + 2 + 2 + 1); /* length */ 396 397 emit_byte(cinfo, 0x41); /* Identifier: ASCII "Adobe" */ 398 emit_byte(cinfo, 0x64); 399 emit_byte(cinfo, 0x6F); 400 emit_byte(cinfo, 0x62); 401 emit_byte(cinfo, 0x65); 402 emit_2bytes(cinfo, 100); /* Version */ 403 emit_2bytes(cinfo, 0); /* Flags0 */ 404 emit_2bytes(cinfo, 0); /* Flags1 */ 405 switch (cinfo->jpeg_color_space) { 406 case JCS_YCbCr: 407 emit_byte(cinfo, 1); /* Color transform = 1 */ 408 break; 409 case JCS_YCCK: 410 emit_byte(cinfo, 2); /* Color transform = 2 */ 411 break; 412 default: 413 emit_byte(cinfo, 0); /* Color transform = 0 */ 414 break; 415 } 416 } 417 418 419 /* 420 * This routine is exported for possible use by applications. 421 * The intended use is to emit COM or APPn markers after calling 422 * jpeg_start_compress() and before the first jpeg_write_scanlines() call 423 * (hence, after write_file_header but before write_frame_header). 424 * Other uses are not guaranteed to produce desirable results. 425 */ 426 427 METHODDEF void 428 write_any_marker (j_compress_ptr cinfo, int marker, 429 const JOCTET *dataptr, unsigned int datalen) 430 /* Emit an arbitrary marker with parameters */ 431 { 432 if (datalen <= (unsigned int) 65533) { /* safety check */ 433 emit_marker(cinfo, (JPEG_MARKER) marker); 434 435 emit_2bytes(cinfo, (int) (datalen + 2)); /* total length */ 436 437 while (datalen--) { 438 emit_byte(cinfo, *dataptr); 439 dataptr++; 440 } 441 } 442 } 443 444 445 /* 446 * Write datastream header. 447 * This consists of an SOI and optional APPn markers. 448 * We recommend use of the JFIF marker, but not the Adobe marker, 449 * when using YCbCr or grayscale data. The JFIF marker should NOT 450 * be used for any other JPEG colorspace. The Adobe marker is helpful 451 * to distinguish RGB, CMYK, and YCCK colorspaces. 452 * Note that an application can write additional header markers after 453 * jpeg_start_compress returns. 454 */ 455 456 METHODDEF void 457 write_file_header (j_compress_ptr cinfo) 458 { 459 emit_marker(cinfo, M_SOI); /* first the SOI */ 460 461 if (cinfo->write_JFIF_header) /* next an optional JFIF APP0 */ 462 emit_jfif_app0(cinfo); 463 if (cinfo->write_Adobe_marker) /* next an optional Adobe APP14 */ 464 emit_adobe_app14(cinfo); 465 } 466 467 468 /* 469 * Write frame header. 470 * This consists of DQT and SOFn markers. 471 * Note that we do not emit the SOF until we have emitted the DQT(s). 472 * This avoids compatibility problems with incorrect implementations that 473 * try to error-check the quant table numbers as soon as they see the SOF. 474 */ 475 476 METHODDEF void 477 write_frame_header (j_compress_ptr cinfo) 478 { 479 int ci, prec; 480 boolean is_baseline; 481 jpeg_component_info *compptr; 482 483 /* Emit DQT for each quantization table. 484 * Note that emit_dqt() suppresses any duplicate tables. 485 */ 486 prec = 0; 487 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 488 ci++, compptr++) { 489 prec += emit_dqt(cinfo, compptr->quant_tbl_no); 490 } 491 /* now prec is nonzero iff there are any 16-bit quant tables. */ 492 493 /* Check for a non-baseline specification. 494 * Note we assume that Huffman table numbers won't be changed later. 495 */ 496 if (cinfo->arith_code || cinfo->progressive_mode || 497 cinfo->data_precision != 8) { 498 is_baseline = FALSE; 499 } else { 500 is_baseline = TRUE; 501 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 502 ci++, compptr++) { 503 if (compptr->dc_tbl_no > 1 || compptr->ac_tbl_no > 1) 504 is_baseline = FALSE; 505 } 506 if (prec && is_baseline) { 507 is_baseline = FALSE; 508 /* If it's baseline except for quantizer size, warn the user */ 509 TRACEMS(cinfo, 0, JTRC_16BIT_TABLES); 510 } 511 } 512 513 /* Emit the proper SOF marker */ 514 if (cinfo->arith_code) { 515 emit_sof(cinfo, M_SOF9); /* SOF code for arithmetic coding */ 516 } else { 517 if (cinfo->progressive_mode) 518 emit_sof(cinfo, M_SOF2); /* SOF code for progressive Huffman */ 519 else if (is_baseline) 520 emit_sof(cinfo, M_SOF0); /* SOF code for baseline implementation */ 521 else 522 emit_sof(cinfo, M_SOF1); /* SOF code for non-baseline Huffman file */ 523 } 524 } 525 526 527 /* 528 * Write scan header. 529 * This consists of DHT or DAC markers, optional DRI, and SOS. 530 * Compressed data will be written following the SOS. 531 */ 532 533 METHODDEF void 534 write_scan_header (j_compress_ptr cinfo) 535 { 536 int i; 537 jpeg_component_info *compptr; 538 539 if (cinfo->arith_code) { 540 /* Emit arith conditioning info. We may have some duplication 541 * if the file has multiple scans, but it's so small it's hardly 542 * worth worrying about. 543 */ 544 emit_dac(cinfo); 545 } else { 546 /* Emit Huffman tables. 547 * Note that emit_dht() suppresses any duplicate tables. 548 */ 549 for (i = 0; i < cinfo->comps_in_scan; i++) { 550 compptr = cinfo->cur_comp_info[i]; 551 if (cinfo->progressive_mode) { 552 /* Progressive mode: only DC or only AC tables are used in one scan */ 553 if (cinfo->Ss == 0) { 554 if (cinfo->Ah == 0) /* DC needs no table for refinement scan */ 555 emit_dht(cinfo, compptr->dc_tbl_no, FALSE); 556 } else { 557 emit_dht(cinfo, compptr->ac_tbl_no, TRUE); 558 } 559 } else { 560 /* Sequential mode: need both DC and AC tables */ 561 emit_dht(cinfo, compptr->dc_tbl_no, FALSE); 562 emit_dht(cinfo, compptr->ac_tbl_no, TRUE); 563 } 564 } 565 } 566 567 /* Emit DRI if required --- note that DRI value could change for each scan. 568 * If it doesn't, a tiny amount of space is wasted in multiple-scan files. 569 * We assume DRI will never be nonzero for one scan and zero for a later one. 570 */ 571 if (cinfo->restart_interval) 572 emit_dri(cinfo); 573 574 emit_sos(cinfo); 575 } 576 577 578 /* 579 * Write datastream trailer. 580 */ 581 582 METHODDEF void 583 write_file_trailer (j_compress_ptr cinfo) 584 { 585 emit_marker(cinfo, M_EOI); 586 } 587 588 589 /* 590 * Write an abbreviated table-specification datastream. 591 * This consists of SOI, DQT and DHT tables, and EOI. 592 * Any table that is defined and not marked sent_table = TRUE will be 593 * emitted. Note that all tables will be marked sent_table = TRUE at exit. 594 */ 595 596 METHODDEF void 597 write_tables_only (j_compress_ptr cinfo) 598 { 599 int i; 600 601 emit_marker(cinfo, M_SOI); 602 603 for (i = 0; i < NUM_QUANT_TBLS; i++) { 604 if (cinfo->quant_tbl_ptrs[i] != NULL) 605 (void) emit_dqt(cinfo, i); 606 } 607 608 if (! cinfo->arith_code) { 609 for (i = 0; i < NUM_HUFF_TBLS; i++) { 610 if (cinfo->dc_huff_tbl_ptrs[i] != NULL) 611 emit_dht(cinfo, i, FALSE); 612 if (cinfo->ac_huff_tbl_ptrs[i] != NULL) 613 emit_dht(cinfo, i, TRUE); 614 } 615 } 616 617 emit_marker(cinfo, M_EOI); 618 } 619 620 621 /* 622 * Initialize the marker writer module. 623 */ 624 625 GLOBAL void 626 jinit_marker_writer (j_compress_ptr cinfo) 627 { 628 /* Create the subobject */ 629 cinfo->marker = (struct jpeg_marker_writer *) 630 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 631 SIZEOF(struct jpeg_marker_writer)); 632 /* Initialize method pointers */ 633 cinfo->marker->write_any_marker = write_any_marker; 634 cinfo->marker->write_file_header = write_file_header; 635 cinfo->marker->write_frame_header = write_frame_header; 636 cinfo->marker->write_scan_header = write_scan_header; 637 cinfo->marker->write_file_trailer = write_file_trailer; 638 cinfo->marker->write_tables_only = write_tables_only; 639 }