1 /*
2 * jctrans.c
3 *
4 * Copyright (C) 1995-1998, 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 library routines for transcoding compression,
9 * that is, writing raw DCT coefficient arrays to an output JPEG file.
10 * The routines in jcapimin.c will also be needed by a transcoder.
11 */
12
13 #define JPEG_INTERNALS
14 #include "jinclude.h"
15 #include "jpeglib.h"
16
17
18 /* Forward declarations */
19 LOCAL(void) transencode_master_selection
20 JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));
21 LOCAL(void) transencode_coef_controller
22 JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));
23
24
25 /*
26 * Compression initialization for writing raw-coefficient data.
27 * Before calling this, all parameters and a data destination must be set up.
28 * Call jpeg_finish_compress() to actually write the data.
29 *
30 * The number of passed virtual arrays must match cinfo->num_components.
31 * Note that the virtual arrays need not be filled or even realized at
32 * the time write_coefficients is called; indeed, if the virtual arrays
33 * were requested from this compression object's memory manager, they
34 * typically will be realized during this routine and filled afterwards.
35 */
36
37 GLOBAL(void)
38 jpeg_write_coefficients (j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays)
39 {
40 if (cinfo->global_state != CSTATE_START)
41 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
42 /* Mark all tables to be written */
43 jpeg_suppress_tables(cinfo, FALSE);
44 /* (Re)initialize error mgr and destination modules */
45 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
46 (*cinfo->dest->init_destination) (cinfo);
47 /* Perform master selection of active modules */
48 transencode_master_selection(cinfo, coef_arrays);
49 /* Wait for jpeg_finish_compress() call */
50 cinfo->next_scanline = 0; /* so jpeg_write_marker works */
51 cinfo->global_state = CSTATE_WRCOEFS;
52 }
53
54
55 /*
56 * Initialize the compression object with default parameters,
57 * then copy from the source object all parameters needed for lossless
58 * transcoding. Parameters that can be varied without loss (such as
59 * scan script and Huffman optimization) are left in their default states.
60 */
61
62 GLOBAL(void)
63 jpeg_copy_critical_parameters (j_decompress_ptr srcinfo,
64 j_compress_ptr dstinfo)
65 {
66 JQUANT_TBL ** qtblptr;
67 jpeg_component_info *incomp, *outcomp;
68 JQUANT_TBL *c_quant, *slot_quant;
69 int tblno, ci, coefi;
70
71 /* Safety check to ensure start_compress not called yet. */
72 if (dstinfo->global_state != CSTATE_START)
73 ERREXIT1(dstinfo, JERR_BAD_STATE, dstinfo->global_state);
74 /* Copy fundamental image dimensions */
75 dstinfo->image_width = srcinfo->image_width;
76 dstinfo->image_height = srcinfo->image_height;
77 dstinfo->input_components = srcinfo->num_components;
78 dstinfo->in_color_space = srcinfo->jpeg_color_space;
79 /* Initialize all parameters to default values */
80 jpeg_set_defaults(dstinfo);
81 /* jpeg_set_defaults may choose wrong colorspace, eg YCbCr if input is RGB.
82 * Fix it to get the right header markers for the image colorspace.
83 */
84 jpeg_set_colorspace(dstinfo, srcinfo->jpeg_color_space);
85 dstinfo->data_precision = srcinfo->data_precision;
86 dstinfo->CCIR601_sampling = srcinfo->CCIR601_sampling;
87 /* Copy the source's quantization tables. */
88 for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
89 if (srcinfo->quant_tbl_ptrs[tblno] != NULL) {
90 qtblptr = & dstinfo->quant_tbl_ptrs[tblno];
91 if (*qtblptr == NULL)
92 *qtblptr = jpeg_alloc_quant_table((j_common_ptr) dstinfo);
93 MEMCOPY((*qtblptr)->quantval,
94 srcinfo->quant_tbl_ptrs[tblno]->quantval,
95 SIZEOF((*qtblptr)->quantval));
96 (*qtblptr)->sent_table = FALSE;
97 }
98 }
99 /* Copy the source's per-component info.
100 * Note we assume jpeg_set_defaults has allocated the dest comp_info array.
101 */
102 dstinfo->num_components = srcinfo->num_components;
103 if (dstinfo->num_components < 1 || dstinfo->num_components > MAX_COMPONENTS)
104 ERREXIT2(dstinfo, JERR_COMPONENT_COUNT, dstinfo->num_components,
105 MAX_COMPONENTS);
106 for (ci = 0, incomp = srcinfo->comp_info, outcomp = dstinfo->comp_info;
107 ci < dstinfo->num_components; ci++, incomp++, outcomp++) {
108 outcomp->component_id = incomp->component_id;
109 outcomp->h_samp_factor = incomp->h_samp_factor;
110 outcomp->v_samp_factor = incomp->v_samp_factor;
111 outcomp->quant_tbl_no = incomp->quant_tbl_no;
112 /* Make sure saved quantization table for component matches the qtable
113 * slot. If not, the input file re-used this qtable slot.
114 * IJG encoder currently cannot duplicate this.
115 */
116 tblno = outcomp->quant_tbl_no;
117 if (tblno < 0 || tblno >= NUM_QUANT_TBLS ||
118 srcinfo->quant_tbl_ptrs[tblno] == NULL)
119 ERREXIT1(dstinfo, JERR_NO_QUANT_TABLE, tblno);
120 slot_quant = srcinfo->quant_tbl_ptrs[tblno];
121 c_quant = incomp->quant_table;
122 if (c_quant != NULL) {
123 for (coefi = 0; coefi < DCTSIZE2; coefi++) {
124 if (c_quant->quantval[coefi] != slot_quant->quantval[coefi])
125 ERREXIT1(dstinfo, JERR_MISMATCHED_QUANT_TABLE, tblno);
126 }
127 }
128 /* Note: we do not copy the source's Huffman table assignments;
129 * instead we rely on jpeg_set_colorspace to have made a suitable choice.
130 */
131 }
132 /* Also copy JFIF version and resolution information, if available.
133 * Strictly speaking this isn't "critical" info, but it's nearly
134 * always appropriate to copy it if available. In particular,
135 * if the application chooses to copy JFIF 1.02 extension markers from
136 * the source file, we need to copy the version to make sure we don't
137 * emit a file that has 1.02 extensions but a claimed version of 1.01.
138 * We will *not*, however, copy version info from mislabeled "2.01" files.
139 */
140 if (srcinfo->saw_JFIF_marker) {
141 if (srcinfo->JFIF_major_version == 1) {
142 dstinfo->JFIF_major_version = srcinfo->JFIF_major_version;
143 dstinfo->JFIF_minor_version = srcinfo->JFIF_minor_version;
144 }
145 dstinfo->density_unit = srcinfo->density_unit;
146 dstinfo->X_density = srcinfo->X_density;
147 dstinfo->Y_density = srcinfo->Y_density;
148 }
149 }
150
151
152 /*
153 * Master selection of compression modules for transcoding.
154 * This substitutes for jcinit.c's initialization of the full compressor.
155 */
156
157 LOCAL(void)
158 transencode_master_selection (j_compress_ptr cinfo,
159 jvirt_barray_ptr * coef_arrays)
160 {
161 /* Although we don't actually use input_components for transcoding,
162 * jcmaster.c's initial_setup will complain if input_components is 0.
163 */
164 cinfo->input_components = 1;
165 /* Initialize master control (includes parameter checking/processing) */
166 jinit_c_master_control(cinfo, TRUE /* transcode only */);
167
168 /* Entropy encoding: either Huffman or arithmetic coding. */
169 if (cinfo->arith_code) {
170 ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
171 } else {
172 jinit_huff_encoder(cinfo);
173 }
174
175 /* We need a special coefficient buffer controller. */
176 transencode_coef_controller(cinfo, coef_arrays);
177
178 jinit_marker_writer(cinfo);
179
180 /* We can now tell the memory manager to allocate virtual arrays. */
181 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
182
183 /* Write the datastream header (SOI, JFIF) immediately.
184 * Frame and scan headers are postponed till later.
185 * This lets application insert special markers after the SOI.
186 */
187 (*cinfo->marker->write_file_header) (cinfo);
188 }
189
190
191 /*
192 * The rest of this file is a special implementation of the coefficient
193 * buffer controller. This is similar to jccoefct.c, but it handles only
194 * output from presupplied virtual arrays. Furthermore, we generate any
195 * dummy padding blocks on-the-fly rather than expecting them to be present
196 * in the arrays.
197 */
198
199 /* Private buffer controller object */
200
201 typedef struct {
202 struct jpeg_c_coef_controller pub; /* public fields */
203
204 JDIMENSION iMCU_row_num; /* iMCU row # within image */
205 JDIMENSION mcu_ctr; /* counts MCUs processed in current row */
206 int MCU_vert_offset; /* counts MCU rows within iMCU row */
207 int MCU_rows_per_iMCU_row; /* number of such rows needed */
208
209 /* Virtual block array for each component. */
210 jvirt_barray_ptr * whole_image;
211
212 /* Workspace for constructing dummy blocks at right/bottom edges. */
213 JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU];
214 } my_coef_controller;
215
216 typedef my_coef_controller * my_coef_ptr;
217
218
219 LOCAL(void)
220 start_iMCU_row (j_compress_ptr cinfo)
221 /* Reset within-iMCU-row counters for a new row */
222 {
223 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
224
225 /* In an interleaved scan, an MCU row is the same as an iMCU row.
226 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
227 * But at the bottom of the image, process only what's left.
228 */
229 if (cinfo->comps_in_scan > 1) {
230 coef->MCU_rows_per_iMCU_row = 1;
231 } else {
232 if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
233 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
234 else
235 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
236 }
237
238 coef->mcu_ctr = 0;
239 coef->MCU_vert_offset = 0;
240 }
241
242
243 /*
244 * Initialize for a processing pass.
245 */
246
247 METHODDEF(void)
248 start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
249 {
250 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
251
252 if (pass_mode != JBUF_CRANK_DEST)
253 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
254
255 coef->iMCU_row_num = 0;
256 start_iMCU_row(cinfo);
257 }
258
259
260 /*
261 * Process some data.
262 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
263 * per call, ie, v_samp_factor block rows for each component in the scan.
264 * The data is obtained from the virtual arrays and fed to the entropy coder.
265 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
266 *
267 * NB: input_buf is ignored; it is likely to be a NULL pointer.
268 */
269
270 METHODDEF(boolean)
271 compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
272 {
273 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
274 JDIMENSION MCU_col_num; /* index of current MCU within row */
275 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
276 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
277 int blkn, ci, xindex, yindex, yoffset, blockcnt;
278 JDIMENSION start_col;
279 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
280 JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
281 JBLOCKROW buffer_ptr;
282 jpeg_component_info *compptr;
283
284 /* Align the virtual buffers for the components used in this scan. */
285 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
286 compptr = cinfo->cur_comp_info[ci];
287 buffer[ci] = (*cinfo->mem->access_virt_barray)
288 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
289 coef->iMCU_row_num * compptr->v_samp_factor,
290 (JDIMENSION) compptr->v_samp_factor, FALSE);
291 }
292
293 /* Loop to process one whole iMCU row */
294 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
295 yoffset++) {
296 for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
297 MCU_col_num++) {
298 /* Construct list of pointers to DCT blocks belonging to this MCU */
299 blkn = 0; /* index of current DCT block within MCU */
300 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
301 compptr = cinfo->cur_comp_info[ci];
302 start_col = MCU_col_num * compptr->MCU_width;
303 blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
304 : compptr->last_col_width;
305 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
306 if (coef->iMCU_row_num < last_iMCU_row ||
307 yindex+yoffset < compptr->last_row_height) {
308 /* Fill in pointers to real blocks in this row */
309 buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
310 for (xindex = 0; xindex < blockcnt; xindex++)
311 MCU_buffer[blkn++] = buffer_ptr++;
312 } else {
313 /* At bottom of image, need a whole row of dummy blocks */
314 xindex = 0;
315 }
316 /* Fill in any dummy blocks needed in this row.
317 * Dummy blocks are filled in the same way as in jccoefct.c:
318 * all zeroes in the AC entries, DC entries equal to previous
319 * block's DC value. The init routine has already zeroed the
320 * AC entries, so we need only set the DC entries correctly.
321 */
322 for (; xindex < compptr->MCU_width; xindex++) {
323 MCU_buffer[blkn] = coef->dummy_buffer[blkn];
324 MCU_buffer[blkn][0][0] = MCU_buffer[blkn-1][0][0];
325 blkn++;
326 }
327 }
328 }
329 /* Try to write the MCU. */
330 if (! (*cinfo->entropy->encode_mcu) (cinfo, MCU_buffer)) {
331 /* Suspension forced; update state counters and exit */
332 coef->MCU_vert_offset = yoffset;
333 coef->mcu_ctr = MCU_col_num;
334 return FALSE;
335 }
336 }
337 /* Completed an MCU row, but perhaps not an iMCU row */
338 coef->mcu_ctr = 0;
339 }
340 /* Completed the iMCU row, advance counters for next one */
341 coef->iMCU_row_num++;
342 start_iMCU_row(cinfo);
343 return TRUE;
344 }
345
346
347 /*
348 * Initialize coefficient buffer controller.
349 *
350 * Each passed coefficient array must be the right size for that
351 * coefficient: width_in_blocks wide and height_in_blocks high,
352 * with unitheight at least v_samp_factor.
353 */
354
355 LOCAL(void)
356 transencode_coef_controller (j_compress_ptr cinfo,
357 jvirt_barray_ptr * coef_arrays)
358 {
359 my_coef_ptr coef;
360 JBLOCKROW buffer;
361 int i;
362
363 coef = (my_coef_ptr)
364 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
365 SIZEOF(my_coef_controller));
366 cinfo->coef = (struct jpeg_c_coef_controller *) coef;
367 coef->pub.start_pass = start_pass_coef;
368 coef->pub.compress_data = compress_output;
369
370 /* Save pointer to virtual arrays */
371 coef->whole_image = coef_arrays;
372
373 /* Allocate and pre-zero space for dummy DCT blocks. */
374 buffer = (JBLOCKROW)
375 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
376 C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
377 jzero_far((void FAR *) buffer, C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
378 for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
379 coef->dummy_buffer[i] = buffer + i;
380 }
381 }