1/*
2 * jcmaster.c
3 *
4 * Copyright (C) 1991-1997, 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 master control logic for the JPEG compressor.
9 * These routines are concerned with parameter validation, initial setup,
10 * and inter-pass control (determining the number of passes and the work
11 * to be done in each pass).
12 */
13
14#define JPEG_INTERNALS
15#include "jinclude.h"
16#include "jpeglib.h"
17
18
19/* Private state */
20
21typedef enum {
22 main_pass, /* input data, also do first output step */
23 huff_opt_pass, /* Huffman code optimization pass */
24 output_pass /* data output pass */
25} c_pass_type;
26
27typedef struct {
28 struct jpeg_comp_master pub; /* public fields */
29
30 c_pass_type pass_type; /* the type of the current pass */
31
32 int pass_number; /* # of passes completed */
33 int total_passes; /* total # of passes needed */
34
35 int scan_number; /* current index in scan_info[] */
36} my_comp_master;
37
38typedef my_comp_master * my_master_ptr;
39
40
41/*
42 * Support routines that do various essential calculations.
43 */
44
45LOCAL(void)
46initial_setup (j_compress_ptr cinfo)
47/* Do computations that are needed before master selection phase */
48{
49 int ci;
50 jpeg_component_info *compptr;
51 long samplesperrow;
52 JDIMENSION jd_samplesperrow;
53
54 /* Sanity check on image dimensions */
55 if (cinfo->image_height <= 0 || cinfo->image_width <= 0
56 || cinfo->num_components <= 0 || cinfo->input_components <= 0)
57 ERREXIT(cinfo, JERR_EMPTY_IMAGE);
58
59 /* Make sure image isn't bigger than I can handle */
60 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
61 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
62 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
63
64 /* Width of an input scanline must be representable as JDIMENSION. */
65 samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components;
66 jd_samplesperrow = (JDIMENSION) samplesperrow;
67 if ((long) jd_samplesperrow != samplesperrow)
68 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
69
70 /* For now, precision must match compiled-in value... */
71 if (cinfo->data_precision != BITS_IN_JSAMPLE)
72 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
73
74 /* Check that number of components won't exceed internal array sizes */
75 if (cinfo->num_components > MAX_COMPONENTS)
76 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
77 MAX_COMPONENTS);
78
79 /* Compute maximum sampling factors; check factor validity */
80 cinfo->max_h_samp_factor = 1;
81 cinfo->max_v_samp_factor = 1;
82 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
83 ci++, compptr++) {
84 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
85 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
86 ERREXIT(cinfo, JERR_BAD_SAMPLING);
87 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
88 compptr->h_samp_factor);
89 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
90 compptr->v_samp_factor);
91 }
92
93 /* Compute dimensions of components */
94 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
95 ci++, compptr++) {
96 /* Fill in the correct component_index value; don't rely on application */
97 compptr->component_index = ci;
98 /* For compression, we never do DCT scaling. */
99 compptr->DCT_scaled_size = DCTSIZE;
100 /* Size in DCT blocks */
101 compptr->width_in_blocks = (JDIMENSION)
102 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
103 (long) (cinfo->max_h_samp_factor * DCTSIZE));
104 compptr->height_in_blocks = (JDIMENSION)
105 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
106 (long) (cinfo->max_v_samp_factor * DCTSIZE));
107 /* Size in samples */
108 compptr->downsampled_width = (JDIMENSION)
109 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
110 (long) cinfo->max_h_samp_factor);
111 compptr->downsampled_height = (JDIMENSION)
112 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
113 (long) cinfo->max_v_samp_factor);
114 /* Mark component needed (this flag isn't actually used for compression) */
115 compptr->component_needed = TRUE;
116 }
117
118 /* Compute number of fully interleaved MCU rows (number of times that
119 * main controller will call coefficient controller).
120 */
121 cinfo->total_iMCU_rows = (JDIMENSION)
122 jdiv_round_up((long) cinfo->image_height,
123 (long) (cinfo->max_v_samp_factor*DCTSIZE));
124}
125
126
127#ifdef C_MULTISCAN_FILES_SUPPORTED
128
129LOCAL(void)
130validate_script (j_compress_ptr cinfo)
131/* Verify that the scan script in cinfo->scan_info[] is valid; also
132 * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
133 */
134{
135 const jpeg_scan_info * scanptr;
136 int scanno, ncomps, ci, coefi, thisi;
137 int Ss, Se, Ah, Al;
138 boolean component_sent[MAX_COMPONENTS];
139#ifdef C_PROGRESSIVE_SUPPORTED
140 int * last_bitpos_ptr;
141 int last_bitpos[MAX_COMPONENTS][DCTSIZE2];
142 /* -1 until that coefficient has been seen; then last Al for it */
143#endif
144
145 if (cinfo->num_scans <= 0)
146 ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);
147
148 /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;
149 * for progressive JPEG, no scan can have this.
150 */
151 scanptr = cinfo->scan_info;
152 if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {
153#ifdef C_PROGRESSIVE_SUPPORTED
154 cinfo->progressive_mode = TRUE;
155 last_bitpos_ptr = & last_bitpos[0][0];
156 for (ci = 0; ci < cinfo->num_components; ci++)
157 for (coefi = 0; coefi < DCTSIZE2; coefi++)
158 *last_bitpos_ptr++ = -1;
159#else
160 ERREXIT(cinfo, JERR_NOT_COMPILED);
161#endif
162 } else {
163 cinfo->progressive_mode = FALSE;
164 for (ci = 0; ci < cinfo->num_components; ci++)
165 component_sent[ci] = FALSE;
166 }
167
168 for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {
169 /* Validate component indexes */
170 ncomps = scanptr->comps_in_scan;
171 if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)
172 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);
173 for (ci = 0; ci < ncomps; ci++) {
174 thisi = scanptr->component_index[ci];
175 if (thisi < 0 || thisi >= cinfo->num_components)
176 ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
177 /* Components must appear in SOF order within each scan */
178 if (ci > 0 && thisi <= scanptr->component_index[ci-1])
179 ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
180 }
181 /* Validate progression parameters */
182 Ss = scanptr->Ss;
183 Se = scanptr->Se;
184 Ah = scanptr->Ah;
185 Al = scanptr->Al;
186 if (cinfo->progressive_mode) {
187#ifdef C_PROGRESSIVE_SUPPORTED
188 /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
189 * seems wrong: the upper bound ought to depend on data precision.
190 * Perhaps they really meant 0..N+1 for N-bit precision.
191 * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
192 * out-of-range reconstructed DC values during the first DC scan,
193 * which might cause problems for some decoders.
194 */
195#if BITS_IN_JSAMPLE == 8
196#define MAX_AH_AL 10
197#else
198#define MAX_AH_AL 13
199#endif
200 if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
201 Ah < 0 || Ah > MAX_AH_AL || Al < 0 || Al > MAX_AH_AL)
202 ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
203 if (Ss == 0) {
204 if (Se != 0) /* DC and AC together not OK */
205 ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
206 } else {
207 if (ncomps != 1) /* AC scans must be for only one component */
208 ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
209 }
210 for (ci = 0; ci < ncomps; ci++) {
211 last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
212 if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
213 ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
214 for (coefi = Ss; coefi <= Se; coefi++) {
215 if (last_bitpos_ptr[coefi] < 0) {
216 /* first scan of this coefficient */
217 if (Ah != 0)
218 ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
219 } else {
220 /* not first scan */
221 if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
222 ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
223 }
224 last_bitpos_ptr[coefi] = Al;
225 }
226 }
227#endif
228 } else {
229 /* For sequential JPEG, all progression parameters must be these: */
230 if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
231 ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
232 /* Make sure components are not sent twice */
233 for (ci = 0; ci < ncomps; ci++) {
234 thisi = scanptr->component_index[ci];
235 if (component_sent[thisi])
236 ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
237 component_sent[thisi] = TRUE;
238 }
239 }
240 }
241
242 /* Now verify that everything got sent. */
243 if (cinfo->progressive_mode) {
244#ifdef C_PROGRESSIVE_SUPPORTED
245 /* For progressive mode, we only check that at least some DC data
246 * got sent for each component; the spec does not require that all bits
247 * of all coefficients be transmitted. Would it be wiser to enforce
248 * transmission of all coefficient bits??
249 */
250 for (ci = 0; ci < cinfo->num_components; ci++) {
251 if (last_bitpos[ci][0] < 0)
252 ERREXIT(cinfo, JERR_MISSING_DATA);
253 }
254#endif
255 } else {
256 for (ci = 0; ci < cinfo->num_components; ci++) {
257 if (! component_sent[ci])
258 ERREXIT(cinfo, JERR_MISSING_DATA);
259 }
260 }
261}
262
263#endif /* C_MULTISCAN_FILES_SUPPORTED */
264
265
266LOCAL(void)
267select_scan_parameters (j_compress_ptr cinfo)
268/* Set up the scan parameters for the current scan */
269{
270 int ci;
271
272#ifdef C_MULTISCAN_FILES_SUPPORTED
273 if (cinfo->scan_info != NULL) {
274 /* Prepare for current scan --- the script is already validated */
275 my_master_ptr master = (my_master_ptr) cinfo->master;
276 const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;
277
278 cinfo->comps_in_scan = scanptr->comps_in_scan;
279 for (ci = 0; ci < scanptr->comps_in_scan; ci++) {
280 cinfo->cur_comp_info[ci] =
281 &cinfo->comp_info[scanptr->component_index[ci]];
282 }
283 cinfo->Ss = scanptr->Ss;
284 cinfo->Se = scanptr->Se;
285 cinfo->Ah = scanptr->Ah;
286 cinfo->Al = scanptr->Al;
287 }
288 else
289#endif
290 {
291 /* Prepare for single sequential-JPEG scan containing all components */
292 if (cinfo->num_components > MAX_COMPS_IN_SCAN)
293 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
294 MAX_COMPS_IN_SCAN);
295 cinfo->comps_in_scan = cinfo->num_components;
296 for (ci = 0; ci < cinfo->num_components; ci++) {
297 cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
298 }
299 cinfo->Ss = 0;
300 cinfo->Se = DCTSIZE2-1;
301 cinfo->Ah = 0;
302 cinfo->Al = 0;
303 }
304}
305
306
307LOCAL(void)
308per_scan_setup (j_compress_ptr cinfo)
309/* Do computations that are needed before processing a JPEG scan */
310/* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
311{
312 int ci, mcublks, tmp;
313 jpeg_component_info *compptr;
314
315 if (cinfo->comps_in_scan == 1) {
316
317 /* Noninterleaved (single-component) scan */
318 compptr = cinfo->cur_comp_info[0];
319
320 /* Overall image size in MCUs */
321 cinfo->MCUs_per_row = compptr->width_in_blocks;
322 cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
323
324 /* For noninterleaved scan, always one block per MCU */
325 compptr->MCU_width = 1;
326 compptr->MCU_height = 1;
327 compptr->MCU_blocks = 1;
328 compptr->MCU_sample_width = DCTSIZE;
329 compptr->last_col_width = 1;
330 /* For noninterleaved scans, it is convenient to define last_row_height
331 * as the number of block rows present in the last iMCU row.
332 */
333 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
334 if (tmp == 0) tmp = compptr->v_samp_factor;
335 compptr->last_row_height = tmp;
336
337 /* Prepare array describing MCU composition */
338 cinfo->blocks_in_MCU = 1;
339 cinfo->MCU_membership[0] = 0;
340
341 } else {
342
343 /* Interleaved (multi-component) scan */
344 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
345 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
346 MAX_COMPS_IN_SCAN);
347
348 /* Overall image size in MCUs */
349 cinfo->MCUs_per_row = (JDIMENSION)
350 jdiv_round_up((long) cinfo->image_width,
351 (long) (cinfo->max_h_samp_factor*DCTSIZE));
352 cinfo->MCU_rows_in_scan = (JDIMENSION)
353 jdiv_round_up((long) cinfo->image_height,
354 (long) (cinfo->max_v_samp_factor*DCTSIZE));
355
356 cinfo->blocks_in_MCU = 0;
357
358 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
359 compptr = cinfo->cur_comp_info[ci];
360 /* Sampling factors give # of blocks of component in each MCU */
361 compptr->MCU_width = compptr->h_samp_factor;
362 compptr->MCU_height = compptr->v_samp_factor;
363 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
364 compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE;
365 /* Figure number of non-dummy blocks in last MCU column & row */
366 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
367 if (tmp == 0) tmp = compptr->MCU_width;
368 compptr->last_col_width = tmp;
369 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
370 if (tmp == 0) tmp = compptr->MCU_height;
371 compptr->last_row_height = tmp;
372 /* Prepare array describing MCU composition */
373 mcublks = compptr->MCU_blocks;
374 if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
375 ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
376 while (mcublks-- > 0) {
377 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
378 }
379 }
380
381 }
382
383 /* Convert restart specified in rows to actual MCU count. */
384 /* Note that count must fit in 16 bits, so we provide limiting. */
385 if (cinfo->restart_in_rows > 0) {
386 long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
387 cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
388 }
389}
390
391
392/*
393 * Per-pass setup.
394 * This is called at the beginning of each pass. We determine which modules
395 * will be active during this pass and give them appropriate start_pass calls.
396 * We also set is_last_pass to indicate whether any more passes will be
397 * required.
398 */
399
400METHODDEF(void)
401prepare_for_pass (j_compress_ptr cinfo)
402{
403 my_master_ptr master = (my_master_ptr) cinfo->master;
404
405 switch (master->pass_type) {
406 case main_pass:
407 /* Initial pass: will collect input data, and do either Huffman
408 * optimization or data output for the first scan.
409 */
410 select_scan_parameters(cinfo);
411 per_scan_setup(cinfo);
412 if (! cinfo->raw_data_in) {
413 (*cinfo->cconvert->start_pass) (cinfo);
414 (*cinfo->downsample->start_pass) (cinfo);
415 (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
416 }
417 (*cinfo->fdct->start_pass) (cinfo);
418 (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);
419 (*cinfo->coef->start_pass) (cinfo,
420 (master->total_passes > 1 ?
421 JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
422 (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
423 if (cinfo->optimize_coding) {
424 /* No immediate data output; postpone writing frame/scan headers */
425 master->pub.call_pass_startup = FALSE;
426 } else {
427 /* Will write frame/scan headers at first jpeg_write_scanlines call */
428 master->pub.call_pass_startup = TRUE;
429 }
430 break;
431#ifdef ENTROPY_OPT_SUPPORTED
432 case huff_opt_pass:
433 /* Do Huffman optimization for a scan after the first one. */
434 select_scan_parameters(cinfo);
435 per_scan_setup(cinfo);
436 if (cinfo->Ss != 0 || cinfo->Ah == 0 || cinfo->arith_code) {
437 (*cinfo->entropy->start_pass) (cinfo, TRUE);
438 (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
439 master->pub.call_pass_startup = FALSE;
440 break;
441 }
442 /* Special case: Huffman DC refinement scans need no Huffman table
443 * and therefore we can skip the optimization pass for them.
444 */
445 master->pass_type = output_pass;
446 master->pass_number++;
447 /*FALLTHROUGH*/
448#endif
449 case output_pass:
450 /* Do a data-output pass. */
451 /* We need not repeat per-scan setup if prior optimization pass did it. */
452 if (! cinfo->optimize_coding) {
453 select_scan_parameters(cinfo);
454 per_scan_setup(cinfo);
455 }
456 (*cinfo->entropy->start_pass) (cinfo, FALSE);
457 (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
458 /* We emit frame/scan headers now */
459 if (master->scan_number == 0)
460 (*cinfo->marker->write_frame_header) (cinfo);
461 (*cinfo->marker->write_scan_header) (cinfo);
462 master->pub.call_pass_startup = FALSE;
463 break;
464 default:
465 ERREXIT(cinfo, JERR_NOT_COMPILED);
466 }
467
468 master->pub.is_last_pass = (master->pass_number == master->total_passes-1);
469
470 /* Set up progress monitor's pass info if present */
471 if (cinfo->progress != NULL) {
472 cinfo->progress->completed_passes = master->pass_number;
473 cinfo->progress->total_passes = master->total_passes;
474 }
475}
476
477
478/*
479 * Special start-of-pass hook.
480 * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
481 * In single-pass processing, we need this hook because we don't want to
482 * write frame/scan headers during jpeg_start_compress; we want to let the
483 * application write COM markers etc. between jpeg_start_compress and the
484 * jpeg_write_scanlines loop.
485 * In multi-pass processing, this routine is not used.
486 */
487
488METHODDEF(void)
489pass_startup (j_compress_ptr cinfo)
490{
491 cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */
492
493 (*cinfo->marker->write_frame_header) (cinfo);
494 (*cinfo->marker->write_scan_header) (cinfo);
495}
496
497
498/*
499 * Finish up at end of pass.
500 */
501
502METHODDEF(void)
503finish_pass_master (j_compress_ptr cinfo)
504{
505 my_master_ptr master = (my_master_ptr) cinfo->master;
506
507 /* The entropy coder always needs an end-of-pass call,
508 * either to analyze statistics or to flush its output buffer.
509 */
510 (*cinfo->entropy->finish_pass) (cinfo);
511
512 /* Update state for next pass */
513 switch (master->pass_type) {
514 case main_pass:
515 /* next pass is either output of scan 0 (after optimization)
516 * or output of scan 1 (if no optimization).
517 */
518 master->pass_type = output_pass;
519 if (! cinfo->optimize_coding)
520 master->scan_number++;
521 break;
522 case huff_opt_pass:
523 /* next pass is always output of current scan */
524 master->pass_type = output_pass;
525 break;
526 case output_pass:
527 /* next pass is either optimization or output of next scan */
528 if (cinfo->optimize_coding)
529 master->pass_type = huff_opt_pass;
530 master->scan_number++;
531 break;
532 }
533
534 master->pass_number++;
535}
536
537
538/*
539 * Initialize master compression control.
540 */
541
542GLOBAL(void)
543jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
544{
545 my_master_ptr master;
546
547 master = (my_master_ptr)
548 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
549 SIZEOF(my_comp_master));
550 cinfo->master = (struct jpeg_comp_master *) master;
551 master->pub.prepare_for_pass = prepare_for_pass;
552 master->pub.pass_startup = pass_startup;
553 master->pub.finish_pass = finish_pass_master;
554 master->pub.is_last_pass = FALSE;
555
556 /* Validate parameters, determine derived values */
557 initial_setup(cinfo);
558
559 if (cinfo->scan_info != NULL) {
560#ifdef C_MULTISCAN_FILES_SUPPORTED
561 validate_script(cinfo);
562#else
563 ERREXIT(cinfo, JERR_NOT_COMPILED);
564#endif
565 } else {
566 cinfo->progressive_mode = FALSE;
567 cinfo->num_scans = 1;
568 }
569
570 if (cinfo->progressive_mode) /* TEMPORARY HACK ??? */
571 cinfo->optimize_coding = TRUE; /* assume default tables no good for progressive mode */
572
573 /* Initialize my private state */
574 if (transcode_only) {
575 /* no main pass in transcoding */
576 if (cinfo->optimize_coding)
577 master->pass_type = huff_opt_pass;
578 else
579 master->pass_type = output_pass;
580 } else {
581 /* for normal compression, first pass is always this type: */
582 master->pass_type = main_pass;
583 }
584 master->scan_number = 0;
585 master->pass_number = 0;
586 if (cinfo->optimize_coding)
587 master->total_passes = cinfo->num_scans * 2;
588 else
589 master->total_passes = cinfo->num_scans;
590}
591