1 /*
2 * jcmarker.c
3 *
4 * Copyright (C) 1991-1998, 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
17 /* Private state */
18
19 typedef struct {
20 struct jpeg_marker_writer pub; /* public fields */
21
22 unsigned int last_restart_interval; /* last DRI value emitted; 0 after SOI */
23 } my_marker_writer;
24
25 typedef my_marker_writer * my_marker_ptr;
26
27
28 /*
29 * Basic output routines.
30 *
31 * Note that we do not support suspension while writing a marker.
32 * Therefore, an application using suspension must ensure that there is
33 * enough buffer space for the initial markers (typ. 600-700 bytes) before
34 * calling jpeg_start_compress, and enough space to write the trailing EOI
35 * (a few bytes) before calling jpeg_finish_compress. Multipass compression
36 * modes are not supported at all with suspension, so those two are the only
37 * points where markers will be written.
38 */
39
40 LOCAL(void)
emit_byte(j_compress_ptr cinfo,int val)41 emit_byte (j_compress_ptr cinfo, int val)
42 /* Emit a byte */
43 {
44 struct jpeg_destination_mgr * dest = cinfo->dest;
45
46 *(dest->next_output_byte)++ = (JOCTET) val;
47 if (--dest->free_in_buffer == 0) {
48 if (! (*dest->empty_output_buffer) (cinfo))
49 ERREXIT(cinfo, JERR_CANT_SUSPEND);
50 }
51 }
52
53
54 LOCAL(void)
emit_marker(j_compress_ptr cinfo,JPEG_MARKER mark)55 emit_marker (j_compress_ptr cinfo, JPEG_MARKER mark)
56 /* Emit a marker code */
57 {
58 emit_byte(cinfo, 0xFF);
59 emit_byte(cinfo, (int) mark);
60 }
61
62
63 LOCAL(void)
emit_2bytes(j_compress_ptr cinfo,int value)64 emit_2bytes (j_compress_ptr cinfo, int value)
65 /* Emit a 2-byte integer; these are always MSB first in JPEG files */
66 {
67 emit_byte(cinfo, (value >> 8) & 0xFF);
68 emit_byte(cinfo, value & 0xFF);
69 }
70
71
72 /*
73 * Routines to write specific marker types.
74 */
75
76 LOCAL(int)
emit_dqt(j_compress_ptr cinfo,int index)77 emit_dqt (j_compress_ptr cinfo, int index)
78 /* Emit a DQT marker */
79 /* Returns the precision used (0 = 8bits, 1 = 16bits) for baseline checking */
80 {
81 JQUANT_TBL * qtbl = cinfo->quant_tbl_ptrs[index];
82 int prec;
83 int i;
84
85 if (qtbl == NULL)
86 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, index);
87
88 prec = 0;
89 for (i = 0; i < DCTSIZE2; i++) {
90 if (qtbl->quantval[i] > 255)
91 prec = 1;
92 }
93
94 if (! qtbl->sent_table) {
95 emit_marker(cinfo, M_DQT);
96
97 emit_2bytes(cinfo, prec ? DCTSIZE2*2 + 1 + 2 : DCTSIZE2 + 1 + 2);
98
99 emit_byte(cinfo, index + (prec<<4));
100
101 for (i = 0; i < DCTSIZE2; i++) {
102 /* The table entries must be emitted in zigzag order. */
103 unsigned int qval = qtbl->quantval[jpeg_natural_order[i]];
104 if (prec)
105 emit_byte(cinfo, (int) (qval >> 8));
106 emit_byte(cinfo, (int) (qval & 0xFF));
107 }
108
109 qtbl->sent_table = TRUE;
110 }
111
112 return prec;
113 }
114
115
116 LOCAL(void)
emit_dht(j_compress_ptr cinfo,int index,boolean is_ac)117 emit_dht (j_compress_ptr cinfo, int index, boolean is_ac)
118 /* Emit a DHT marker */
119 {
120 JHUFF_TBL * htbl;
121 int length, i;
122
123 if (is_ac) {
124 htbl = cinfo->ac_huff_tbl_ptrs[index];
125 index += 0x10; /* output index has AC bit set */
126 } else {
127 htbl = cinfo->dc_huff_tbl_ptrs[index];
128 }
129
130 if (htbl == NULL)
131 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, index);
132
133 if (! htbl->sent_table) {
134 emit_marker(cinfo, M_DHT);
135
136 length = 0;
137 for (i = 1; i <= 16; i++)
138 length += htbl->bits[i];
139
140 emit_2bytes(cinfo, length + 2 + 1 + 16);
141 emit_byte(cinfo, index);
142
143 for (i = 1; i <= 16; i++)
144 emit_byte(cinfo, htbl->bits[i]);
145
146 for (i = 0; i < length; i++)
147 emit_byte(cinfo, htbl->huffval[i]);
148
149 htbl->sent_table = TRUE;
150 }
151 }
152
153
154 LOCAL(void)
emit_dac(j_compress_ptr)155 emit_dac (j_compress_ptr)
156 /* Emit a DAC marker */
157 /* Since the useful info is so small, we want to emit all the tables in */
158 /* one DAC marker. Therefore this routine does its own scan of the table. */
159 {
160 #ifdef C_ARITH_CODING_SUPPORTED
161 char dc_in_use[NUM_ARITH_TBLS];
162 char ac_in_use[NUM_ARITH_TBLS];
163 int length, i;
164 jpeg_component_info *compptr;
165
166 for (i = 0; i < NUM_ARITH_TBLS; i++)
167 dc_in_use[i] = ac_in_use[i] = 0;
168
169 for (i = 0; i < cinfo->comps_in_scan; i++) {
170 compptr = cinfo->cur_comp_info[i];
171 dc_in_use[compptr->dc_tbl_no] = 1;
172 ac_in_use[compptr->ac_tbl_no] = 1;
173 }
174
175 length = 0;
176 for (i = 0; i < NUM_ARITH_TBLS; i++)
177 length += dc_in_use[i] + ac_in_use[i];
178
179 emit_marker(cinfo, M_DAC);
180
181 emit_2bytes(cinfo, length*2 + 2);
182
183 for (i = 0; i < NUM_ARITH_TBLS; i++) {
184 if (dc_in_use[i]) {
185 emit_byte(cinfo, i);
186 emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
187 }
188 if (ac_in_use[i]) {
189 emit_byte(cinfo, i + 0x10);
190 emit_byte(cinfo, cinfo->arith_ac_K[i]);
191 }
192 }
193 #endif /* C_ARITH_CODING_SUPPORTED */
194 }
195
196
197 LOCAL(void)
emit_dri(j_compress_ptr cinfo)198 emit_dri (j_compress_ptr cinfo)
199 /* Emit a DRI marker */
200 {
201 emit_marker(cinfo, M_DRI);
202
203 emit_2bytes(cinfo, 4); /* fixed length */
204
205 emit_2bytes(cinfo, (int) cinfo->restart_interval);
206 }
207
208
209 LOCAL(void)
emit_sof(j_compress_ptr cinfo,JPEG_MARKER code)210 emit_sof (j_compress_ptr cinfo, JPEG_MARKER code)
211 /* Emit a SOF marker */
212 {
213 int ci;
214 jpeg_component_info *compptr;
215
216 emit_marker(cinfo, code);
217
218 emit_2bytes(cinfo, 3 * cinfo->num_components + 2 + 5 + 1); /* length */
219
220 /* Make sure image isn't bigger than SOF field can handle */
221 if ((long) cinfo->image_height > 65535L ||
222 (long) cinfo->image_width > 65535L)
223 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) 65535);
224
225 emit_byte(cinfo, cinfo->data_precision);
226 emit_2bytes(cinfo, (int) cinfo->image_height);
227 emit_2bytes(cinfo, (int) cinfo->image_width);
228
229 emit_byte(cinfo, cinfo->num_components);
230
231 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
232 ci++, compptr++) {
233 emit_byte(cinfo, compptr->component_id);
234 emit_byte(cinfo, (compptr->h_samp_factor << 4) + compptr->v_samp_factor);
235 emit_byte(cinfo, compptr->quant_tbl_no);
236 }
237 }
238
239
240 LOCAL(void)
emit_sos(j_compress_ptr cinfo)241 emit_sos (j_compress_ptr cinfo)
242 /* Emit a SOS marker */
243 {
244 int i, td, ta;
245 jpeg_component_info *compptr;
246
247 emit_marker(cinfo, M_SOS);
248
249 emit_2bytes(cinfo, 2 * cinfo->comps_in_scan + 2 + 1 + 3); /* length */
250
251 emit_byte(cinfo, cinfo->comps_in_scan);
252
253 for (i = 0; i < cinfo->comps_in_scan; i++) {
254 compptr = cinfo->cur_comp_info[i];
255 emit_byte(cinfo, compptr->component_id);
256 td = compptr->dc_tbl_no;
257 ta = compptr->ac_tbl_no;
258 if (cinfo->progressive_mode) {
259 /* Progressive mode: only DC or only AC tables are used in one scan;
260 * furthermore, Huffman coding of DC refinement uses no table at all.
261 * We emit 0 for unused field(s); this is recommended by the P&M text
262 * but does not seem to be specified in the standard.
263 */
264 if (cinfo->Ss == 0) {
265 ta = 0; /* DC scan */
266 if (cinfo->Ah != 0 && !cinfo->arith_code)
267 td = 0; /* no DC table either */
268 } else {
269 td = 0; /* AC scan */
270 }
271 }
272 emit_byte(cinfo, (td << 4) + ta);
273 }
274
275 emit_byte(cinfo, cinfo->Ss);
276 emit_byte(cinfo, cinfo->Se);
277 emit_byte(cinfo, (cinfo->Ah << 4) + cinfo->Al);
278 }
279
280
281 LOCAL(void)
emit_jfif_app0(j_compress_ptr cinfo)282 emit_jfif_app0 (j_compress_ptr cinfo)
283 /* Emit a JFIF-compliant APP0 marker */
284 {
285 /*
286 * Length of APP0 block (2 bytes)
287 * Block ID (4 bytes - ASCII "JFIF")
288 * Zero byte (1 byte to terminate the ID string)
289 * Version Major, Minor (2 bytes - major first)
290 * Units (1 byte - 0x00 = none, 0x01 = inch, 0x02 = cm)
291 * Xdpu (2 bytes - dots per unit horizontal)
292 * Ydpu (2 bytes - dots per unit vertical)
293 * Thumbnail X size (1 byte)
294 * Thumbnail Y size (1 byte)
295 */
296
297 emit_marker(cinfo, M_APP0);
298
299 emit_2bytes(cinfo, 2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1); /* length */
300
301 emit_byte(cinfo, 0x4A); /* Identifier: ASCII "JFIF" */
302 emit_byte(cinfo, 0x46);
303 emit_byte(cinfo, 0x49);
304 emit_byte(cinfo, 0x46);
305 emit_byte(cinfo, 0);
306 emit_byte(cinfo, cinfo->JFIF_major_version); /* Version fields */
307 emit_byte(cinfo, cinfo->JFIF_minor_version);
308 emit_byte(cinfo, cinfo->density_unit); /* Pixel size information */
309 emit_2bytes(cinfo, (int) cinfo->X_density);
310 emit_2bytes(cinfo, (int) cinfo->Y_density);
311 emit_byte(cinfo, 0); /* No thumbnail image */
312 emit_byte(cinfo, 0);
313 }
314
315
316 LOCAL(void)
emit_adobe_app14(j_compress_ptr cinfo)317 emit_adobe_app14 (j_compress_ptr cinfo)
318 /* Emit an Adobe APP14 marker */
319 {
320 /*
321 * Length of APP14 block (2 bytes)
322 * Block ID (5 bytes - ASCII "Adobe")
323 * Version Number (2 bytes - currently 100)
324 * Flags0 (2 bytes - currently 0)
325 * Flags1 (2 bytes - currently 0)
326 * Color transform (1 byte)
327 *
328 * Although Adobe TN 5116 mentions Version = 101, all the Adobe files
329 * now in circulation seem to use Version = 100, so that's what we write.
330 *
331 * We write the color transform byte as 1 if the JPEG color space is
332 * YCbCr, 2 if it's YCCK, 0 otherwise. Adobe's definition has to do with
333 * whether the encoder performed a transformation, which is pretty useless.
334 */
335
336 emit_marker(cinfo, M_APP14);
337
338 emit_2bytes(cinfo, 2 + 5 + 2 + 2 + 2 + 1); /* length */
339
340 emit_byte(cinfo, 0x41); /* Identifier: ASCII "Adobe" */
341 emit_byte(cinfo, 0x64);
342 emit_byte(cinfo, 0x6F);
343 emit_byte(cinfo, 0x62);
344 emit_byte(cinfo, 0x65);
345 emit_2bytes(cinfo, 100); /* Version */
346 emit_2bytes(cinfo, 0); /* Flags0 */
347 emit_2bytes(cinfo, 0); /* Flags1 */
348 switch (cinfo->jpeg_color_space) {
349 case JCS_YCbCr:
350 emit_byte(cinfo, 1); /* Color transform = 1 */
351 break;
352 case JCS_YCCK:
353 emit_byte(cinfo, 2); /* Color transform = 2 */
354 break;
355 default:
356 emit_byte(cinfo, 0); /* Color transform = 0 */
357 break;
358 }
359 }
360
361
362 /*
363 * These routines allow writing an arbitrary marker with parameters.
364 * The only intended use is to emit COM or APPn markers after calling
365 * write_file_header and before calling write_frame_header.
366 * Other uses are not guaranteed to produce desirable results.
367 * Counting the parameter bytes properly is the caller's responsibility.
368 */
369
370 METHODDEF(void)
write_marker_header(j_compress_ptr cinfo,int marker,unsigned int datalen)371 write_marker_header (j_compress_ptr cinfo, int marker, unsigned int datalen)
372 /* Emit an arbitrary marker header */
373 {
374 if (datalen > (unsigned int) 65533) /* safety check */
375 ERREXIT(cinfo, JERR_BAD_LENGTH);
376
377 emit_marker(cinfo, (JPEG_MARKER) marker);
378
379 emit_2bytes(cinfo, (int) (datalen + 2)); /* total length */
380 }
381
382 METHODDEF(void)
write_marker_byte(j_compress_ptr cinfo,int val)383 write_marker_byte (j_compress_ptr cinfo, int val)
384 /* Emit one byte of marker parameters following write_marker_header */
385 {
386 emit_byte(cinfo, val);
387 }
388
389
390 /*
391 * Write datastream header.
392 * This consists of an SOI and optional APPn markers.
393 * We recommend use of the JFIF marker, but not the Adobe marker,
394 * when using YCbCr or grayscale data. The JFIF marker should NOT
395 * be used for any other JPEG colorspace. The Adobe marker is helpful
396 * to distinguish RGB, CMYK, and YCCK colorspaces.
397 * Note that an application can write additional header markers after
398 * jpeg_start_compress returns.
399 */
400
401 METHODDEF(void)
write_file_header(j_compress_ptr cinfo)402 write_file_header (j_compress_ptr cinfo)
403 {
404 my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
405
406 emit_marker(cinfo, M_SOI); /* first the SOI */
407
408 /* SOI is defined to reset restart interval to 0 */
409 marker->last_restart_interval = 0;
410
411 if (cinfo->write_JFIF_header) /* next an optional JFIF APP0 */
412 emit_jfif_app0(cinfo);
413 if (cinfo->write_Adobe_marker) /* next an optional Adobe APP14 */
414 emit_adobe_app14(cinfo);
415 }
416
417
418 /*
419 * Write frame header.
420 * This consists of DQT and SOFn markers.
421 * Note that we do not emit the SOF until we have emitted the DQT(s).
422 * This avoids compatibility problems with incorrect implementations that
423 * try to error-check the quant table numbers as soon as they see the SOF.
424 */
425
426 METHODDEF(void)
write_frame_header(j_compress_ptr cinfo)427 write_frame_header (j_compress_ptr cinfo)
428 {
429 int ci, prec;
430 boolean is_baseline;
431 jpeg_component_info *compptr;
432
433 /* Emit DQT for each quantization table.
434 * Note that emit_dqt() suppresses any duplicate tables.
435 */
436 prec = 0;
437 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
438 ci++, compptr++) {
439 prec += emit_dqt(cinfo, compptr->quant_tbl_no);
440 }
441 /* now prec is nonzero iff there are any 16-bit quant tables. */
442
443 /* Check for a non-baseline specification.
444 * Note we assume that Huffman table numbers won't be changed later.
445 */
446 if (cinfo->arith_code || cinfo->progressive_mode ||
447 cinfo->data_precision != 8) {
448 is_baseline = FALSE;
449 } else {
450 is_baseline = TRUE;
451 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
452 ci++, compptr++) {
453 if (compptr->dc_tbl_no > 1 || compptr->ac_tbl_no > 1)
454 is_baseline = FALSE;
455 }
456 if (prec && is_baseline) {
457 is_baseline = FALSE;
458 /* If it's baseline except for quantizer size, warn the user */
459 TRACEMS(cinfo, 0, JTRC_16BIT_TABLES);
460 }
461 }
462
463 /* Emit the proper SOF marker */
464 if (cinfo->arith_code) {
465 emit_sof(cinfo, M_SOF9); /* SOF code for arithmetic coding */
466 } else {
467 if (cinfo->progressive_mode)
468 emit_sof(cinfo, M_SOF2); /* SOF code for progressive Huffman */
469 else if (is_baseline)
470 emit_sof(cinfo, M_SOF0); /* SOF code for baseline implementation */
471 else
472 emit_sof(cinfo, M_SOF1); /* SOF code for non-baseline Huffman file */
473 }
474 }
475
476
477 /*
478 * Write scan header.
479 * This consists of DHT or DAC markers, optional DRI, and SOS.
480 * Compressed data will be written following the SOS.
481 */
482
483 METHODDEF(void)
write_scan_header(j_compress_ptr cinfo)484 write_scan_header (j_compress_ptr cinfo)
485 {
486 my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
487 int i;
488 jpeg_component_info *compptr;
489
490 if (cinfo->arith_code) {
491 /* Emit arith conditioning info. We may have some duplication
492 * if the file has multiple scans, but it's so small it's hardly
493 * worth worrying about.
494 */
495 emit_dac(cinfo);
496 } else {
497 /* Emit Huffman tables.
498 * Note that emit_dht() suppresses any duplicate tables.
499 */
500 for (i = 0; i < cinfo->comps_in_scan; i++) {
501 compptr = cinfo->cur_comp_info[i];
502 if (cinfo->progressive_mode) {
503 /* Progressive mode: only DC or only AC tables are used in one scan */
504 if (cinfo->Ss == 0) {
505 if (cinfo->Ah == 0) /* DC needs no table for refinement scan */
506 emit_dht(cinfo, compptr->dc_tbl_no, FALSE);
507 } else {
508 emit_dht(cinfo, compptr->ac_tbl_no, TRUE);
509 }
510 } else {
511 /* Sequential mode: need both DC and AC tables */
512 emit_dht(cinfo, compptr->dc_tbl_no, FALSE);
513 emit_dht(cinfo, compptr->ac_tbl_no, TRUE);
514 }
515 }
516 }
517
518 /* Emit DRI if required --- note that DRI value could change for each scan.
519 * We avoid wasting space with unnecessary DRIs, however.
520 */
521 if (cinfo->restart_interval != marker->last_restart_interval) {
522 emit_dri(cinfo);
523 marker->last_restart_interval = cinfo->restart_interval;
524 }
525
526 emit_sos(cinfo);
527 }
528
529
530 /*
531 * Write datastream trailer.
532 */
533
534 METHODDEF(void)
write_file_trailer(j_compress_ptr cinfo)535 write_file_trailer (j_compress_ptr cinfo)
536 {
537 emit_marker(cinfo, M_EOI);
538 }
539
540
541 /*
542 * Write an abbreviated table-specification datastream.
543 * This consists of SOI, DQT and DHT tables, and EOI.
544 * Any table that is defined and not marked sent_table = TRUE will be
545 * emitted. Note that all tables will be marked sent_table = TRUE at exit.
546 */
547
548 METHODDEF(void)
write_tables_only(j_compress_ptr cinfo)549 write_tables_only (j_compress_ptr cinfo)
550 {
551 int i;
552
553 emit_marker(cinfo, M_SOI);
554
555 for (i = 0; i < NUM_QUANT_TBLS; i++) {
556 if (cinfo->quant_tbl_ptrs[i] != NULL)
557 (void) emit_dqt(cinfo, i);
558 }
559
560 if (! cinfo->arith_code) {
561 for (i = 0; i < NUM_HUFF_TBLS; i++) {
562 if (cinfo->dc_huff_tbl_ptrs[i] != NULL)
563 emit_dht(cinfo, i, FALSE);
564 if (cinfo->ac_huff_tbl_ptrs[i] != NULL)
565 emit_dht(cinfo, i, TRUE);
566 }
567 }
568
569 emit_marker(cinfo, M_EOI);
570 }
571
572
573 /*
574 * Initialize the marker writer module.
575 */
576
577 GLOBAL(void)
jinit_marker_writer(j_compress_ptr cinfo)578 jinit_marker_writer (j_compress_ptr cinfo)
579 {
580 my_marker_ptr marker;
581
582 /* Create the subobject */
583 marker = (my_marker_ptr)
584 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
585 SIZEOF(my_marker_writer));
586 cinfo->marker = (struct jpeg_marker_writer *) marker;
587 /* Initialize method pointers */
588 marker->pub.write_file_header = write_file_header;
589 marker->pub.write_frame_header = write_frame_header;
590 marker->pub.write_scan_header = write_scan_header;
591 marker->pub.write_file_trailer = write_file_trailer;
592 marker->pub.write_tables_only = write_tables_only;
593 marker->pub.write_marker_header = write_marker_header;
594 marker->pub.write_marker_byte = write_marker_byte;
595 /* Initialize private state */
596 marker->last_restart_interval = 0;
597 }
598