4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1995-1998, Thomas G. Lane.
6 * Modified 2000-2009 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright (C) 2020, 2022, D. R. Commander.
9 * For conditions of distribution and use, see the accompanying README.ijg
12 * This file contains library routines for transcoding compression,
13 * that is, writing raw DCT coefficient arrays to an output JPEG file.
14 * The routines in jcapimin.c will also be needed by a transcoder.
17 #define JPEG_INTERNALS
20 #include "jpegapicomp.h"
23 /* Forward declarations */
24 LOCAL(void) transencode_master_selection(j_compress_ptr cinfo,
25 jvirt_barray_ptr *coef_arrays);
26 LOCAL(void) transencode_coef_controller(j_compress_ptr cinfo,
27 jvirt_barray_ptr *coef_arrays);
31 * Compression initialization for writing raw-coefficient data.
32 * Before calling this, all parameters and a data destination must be set up.
33 * Call jpeg_finish_compress() to actually write the data.
35 * The number of passed virtual arrays must match cinfo->num_components.
36 * Note that the virtual arrays need not be filled or even realized at
37 * the time write_coefficients is called; indeed, if the virtual arrays
38 * were requested from this compression object's memory manager, they
39 * typically will be realized during this routine and filled afterwards.
43 jpeg_write_coefficients(j_compress_ptr cinfo, jvirt_barray_ptr *coef_arrays)
45 if (cinfo->master->lossless)
46 ERREXIT(cinfo, JERR_NOTIMPL);
48 if (cinfo->global_state != CSTATE_START)
49 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
50 /* Mark all tables to be written */
51 jpeg_suppress_tables(cinfo, FALSE);
52 /* (Re)initialize error mgr and destination modules */
53 (*cinfo->err->reset_error_mgr) ((j_common_ptr)cinfo);
54 (*cinfo->dest->init_destination) (cinfo);
55 /* Perform master selection of active modules */
56 transencode_master_selection(cinfo, coef_arrays);
57 /* Wait for jpeg_finish_compress() call */
58 cinfo->next_scanline = 0; /* so jpeg_write_marker works */
59 cinfo->global_state = CSTATE_WRCOEFS;
64 * Initialize the compression object with default parameters,
65 * then copy from the source object all parameters needed for lossless
66 * transcoding. Parameters that can be varied without loss (such as
67 * scan script and Huffman optimization) are left in their default states.
71 jpeg_copy_critical_parameters(j_decompress_ptr srcinfo, j_compress_ptr dstinfo)
74 jpeg_component_info *incomp, *outcomp;
75 JQUANT_TBL *c_quant, *slot_quant;
78 if (srcinfo->master->lossless)
79 ERREXIT(dstinfo, JERR_NOTIMPL);
81 /* Safety check to ensure start_compress not called yet. */
82 if (dstinfo->global_state != CSTATE_START)
83 ERREXIT1(dstinfo, JERR_BAD_STATE, dstinfo->global_state);
84 /* Copy fundamental image dimensions */
85 dstinfo->image_width = srcinfo->image_width;
86 dstinfo->image_height = srcinfo->image_height;
87 dstinfo->input_components = srcinfo->num_components;
88 dstinfo->in_color_space = srcinfo->jpeg_color_space;
89 #if JPEG_LIB_VERSION >= 70
90 dstinfo->jpeg_width = srcinfo->output_width;
91 dstinfo->jpeg_height = srcinfo->output_height;
92 dstinfo->min_DCT_h_scaled_size = srcinfo->min_DCT_h_scaled_size;
93 dstinfo->min_DCT_v_scaled_size = srcinfo->min_DCT_v_scaled_size;
95 /* Initialize all parameters to default values */
96 jpeg_set_defaults(dstinfo);
97 /* jpeg_set_defaults may choose wrong colorspace, eg YCbCr if input is RGB.
98 * Fix it to get the right header markers for the image colorspace.
100 jpeg_set_colorspace(dstinfo, srcinfo->jpeg_color_space);
101 dstinfo->data_precision = srcinfo->data_precision;
102 dstinfo->CCIR601_sampling = srcinfo->CCIR601_sampling;
103 /* Copy the source's quantization tables. */
104 for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
105 if (srcinfo->quant_tbl_ptrs[tblno] != NULL) {
106 qtblptr = &dstinfo->quant_tbl_ptrs[tblno];
107 if (*qtblptr == NULL)
108 *qtblptr = jpeg_alloc_quant_table((j_common_ptr)dstinfo);
109 memcpy((*qtblptr)->quantval, srcinfo->quant_tbl_ptrs[tblno]->quantval,
110 sizeof((*qtblptr)->quantval));
111 (*qtblptr)->sent_table = FALSE;
114 /* Copy the source's per-component info.
115 * Note we assume jpeg_set_defaults has allocated the dest comp_info array.
117 dstinfo->num_components = srcinfo->num_components;
118 if (dstinfo->num_components < 1 || dstinfo->num_components > MAX_COMPONENTS)
119 ERREXIT2(dstinfo, JERR_COMPONENT_COUNT, dstinfo->num_components,
121 for (ci = 0, incomp = srcinfo->comp_info, outcomp = dstinfo->comp_info;
122 ci < dstinfo->num_components; ci++, incomp++, outcomp++) {
123 outcomp->component_id = incomp->component_id;
124 outcomp->h_samp_factor = incomp->h_samp_factor;
125 outcomp->v_samp_factor = incomp->v_samp_factor;
126 outcomp->quant_tbl_no = incomp->quant_tbl_no;
127 /* Make sure saved quantization table for component matches the qtable
128 * slot. If not, the input file re-used this qtable slot.
129 * IJG encoder currently cannot duplicate this.
131 tblno = outcomp->quant_tbl_no;
132 if (tblno < 0 || tblno >= NUM_QUANT_TBLS ||
133 srcinfo->quant_tbl_ptrs[tblno] == NULL)
134 ERREXIT1(dstinfo, JERR_NO_QUANT_TABLE, tblno);
135 slot_quant = srcinfo->quant_tbl_ptrs[tblno];
136 c_quant = incomp->quant_table;
137 if (c_quant != NULL) {
138 for (coefi = 0; coefi < DCTSIZE2; coefi++) {
139 if (c_quant->quantval[coefi] != slot_quant->quantval[coefi])
140 ERREXIT1(dstinfo, JERR_MISMATCHED_QUANT_TABLE, tblno);
143 /* Note: we do not copy the source's Huffman table assignments;
144 * instead we rely on jpeg_set_colorspace to have made a suitable choice.
147 /* Also copy JFIF version and resolution information, if available.
148 * Strictly speaking this isn't "critical" info, but it's nearly
149 * always appropriate to copy it if available. In particular,
150 * if the application chooses to copy JFIF 1.02 extension markers from
151 * the source file, we need to copy the version to make sure we don't
152 * emit a file that has 1.02 extensions but a claimed version of 1.01.
153 * We will *not*, however, copy version info from mislabeled "2.01" files.
155 if (srcinfo->saw_JFIF_marker) {
156 if (srcinfo->JFIF_major_version == 1) {
157 dstinfo->JFIF_major_version = srcinfo->JFIF_major_version;
158 dstinfo->JFIF_minor_version = srcinfo->JFIF_minor_version;
160 dstinfo->density_unit = srcinfo->density_unit;
161 dstinfo->X_density = srcinfo->X_density;
162 dstinfo->Y_density = srcinfo->Y_density;
168 * Master selection of compression modules for transcoding.
169 * This substitutes for jcinit.c's initialization of the full compressor.
173 transencode_master_selection(j_compress_ptr cinfo,
174 jvirt_barray_ptr *coef_arrays)
176 /* Although we don't actually use input_components for transcoding,
177 * jcmaster.c's initial_setup will complain if input_components is 0.
179 cinfo->input_components = 1;
180 /* Initialize master control (includes parameter checking/processing) */
181 jinit_c_master_control(cinfo, TRUE /* transcode only */);
183 /* Entropy encoding: either Huffman or arithmetic coding. */
184 if (cinfo->arith_code) {
185 #ifdef C_ARITH_CODING_SUPPORTED
186 jinit_arith_encoder(cinfo);
188 ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
191 if (cinfo->progressive_mode) {
192 #ifdef C_PROGRESSIVE_SUPPORTED
193 jinit_phuff_encoder(cinfo);
195 ERREXIT(cinfo, JERR_NOT_COMPILED);
198 jinit_huff_encoder(cinfo);
201 /* We need a special coefficient buffer controller. */
202 transencode_coef_controller(cinfo, coef_arrays);
204 jinit_marker_writer(cinfo);
206 /* We can now tell the memory manager to allocate virtual arrays. */
207 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);
209 /* Write the datastream header (SOI, JFIF) immediately.
210 * Frame and scan headers are postponed till later.
211 * This lets application insert special markers after the SOI.
213 (*cinfo->marker->write_file_header) (cinfo);
218 * The rest of this file is a special implementation of the coefficient
219 * buffer controller. This is similar to jccoefct.c, but it handles only
220 * output from presupplied virtual arrays. Furthermore, we generate any
221 * dummy padding blocks on-the-fly rather than expecting them to be present
225 /* Private buffer controller object */
228 struct jpeg_c_coef_controller pub; /* public fields */
230 JDIMENSION iMCU_row_num; /* iMCU row # within image */
231 JDIMENSION mcu_ctr; /* counts MCUs processed in current row */
232 int MCU_vert_offset; /* counts MCU rows within iMCU row */
233 int MCU_rows_per_iMCU_row; /* number of such rows needed */
235 /* Virtual block array for each component. */
236 jvirt_barray_ptr *whole_image;
238 /* Workspace for constructing dummy blocks at right/bottom edges. */
239 JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU];
240 } my_coef_controller;
242 typedef my_coef_controller *my_coef_ptr;
246 start_iMCU_row(j_compress_ptr cinfo)
247 /* Reset within-iMCU-row counters for a new row */
249 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
251 /* In an interleaved scan, an MCU row is the same as an iMCU row.
252 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
253 * But at the bottom of the image, process only what's left.
255 if (cinfo->comps_in_scan > 1) {
256 coef->MCU_rows_per_iMCU_row = 1;
258 if (coef->iMCU_row_num < (cinfo->total_iMCU_rows - 1))
259 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
261 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
265 coef->MCU_vert_offset = 0;
270 * Initialize for a processing pass.
274 start_pass_coef(j_compress_ptr cinfo, J_BUF_MODE pass_mode)
276 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
278 if (pass_mode != JBUF_CRANK_DEST)
279 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
281 coef->iMCU_row_num = 0;
282 start_iMCU_row(cinfo);
288 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
289 * per call, ie, v_samp_factor block rows for each component in the scan.
290 * The data is obtained from the virtual arrays and fed to the entropy coder.
291 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
293 * NB: input_buf is ignored; it is likely to be a NULL pointer.
297 compress_output(j_compress_ptr cinfo, JSAMPIMAGE input_buf)
299 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
300 JDIMENSION MCU_col_num; /* index of current MCU within row */
301 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
302 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
303 int blkn, ci, xindex, yindex, yoffset, blockcnt;
304 JDIMENSION start_col;
305 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
306 JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
307 JBLOCKROW buffer_ptr;
308 jpeg_component_info *compptr;
310 /* Align the virtual buffers for the components used in this scan. */
311 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
312 compptr = cinfo->cur_comp_info[ci];
313 buffer[ci] = (*cinfo->mem->access_virt_barray)
314 ((j_common_ptr)cinfo, coef->whole_image[compptr->component_index],
315 coef->iMCU_row_num * compptr->v_samp_factor,
316 (JDIMENSION)compptr->v_samp_factor, FALSE);
319 /* Loop to process one whole iMCU row */
320 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
322 for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
324 /* Construct list of pointers to DCT blocks belonging to this MCU */
325 blkn = 0; /* index of current DCT block within MCU */
326 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
327 compptr = cinfo->cur_comp_info[ci];
328 start_col = MCU_col_num * compptr->MCU_width;
329 blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width :
330 compptr->last_col_width;
331 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
332 if (coef->iMCU_row_num < last_iMCU_row ||
333 yindex + yoffset < compptr->last_row_height) {
334 /* Fill in pointers to real blocks in this row */
335 buffer_ptr = buffer[ci][yindex + yoffset] + start_col;
336 for (xindex = 0; xindex < blockcnt; xindex++)
337 MCU_buffer[blkn++] = buffer_ptr++;
339 /* At bottom of image, need a whole row of dummy blocks */
342 /* Fill in any dummy blocks needed in this row.
343 * Dummy blocks are filled in the same way as in jccoefct.c:
344 * all zeroes in the AC entries, DC entries equal to previous
345 * block's DC value. The init routine has already zeroed the
346 * AC entries, so we need only set the DC entries correctly.
348 for (; xindex < compptr->MCU_width; xindex++) {
349 MCU_buffer[blkn] = coef->dummy_buffer[blkn];
350 MCU_buffer[blkn][0][0] = MCU_buffer[blkn - 1][0][0];
355 /* Try to write the MCU. */
356 if (!(*cinfo->entropy->encode_mcu) (cinfo, MCU_buffer)) {
357 /* Suspension forced; update state counters and exit */
358 coef->MCU_vert_offset = yoffset;
359 coef->mcu_ctr = MCU_col_num;
363 /* Completed an MCU row, but perhaps not an iMCU row */
366 /* Completed the iMCU row, advance counters for next one */
367 coef->iMCU_row_num++;
368 start_iMCU_row(cinfo);
374 compress_output_12(j_compress_ptr cinfo, J12SAMPIMAGE input_buf)
376 return compress_output(cinfo, (JSAMPIMAGE)input_buf);
381 * Initialize coefficient buffer controller.
383 * Each passed coefficient array must be the right size for that
384 * coefficient: width_in_blocks wide and height_in_blocks high,
385 * with unitheight at least v_samp_factor.
389 transencode_coef_controller(j_compress_ptr cinfo,
390 jvirt_barray_ptr *coef_arrays)
397 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
398 sizeof(my_coef_controller));
399 cinfo->coef = (struct jpeg_c_coef_controller *)coef;
400 coef->pub.start_pass = start_pass_coef;
401 coef->pub.compress_data = compress_output;
402 coef->pub.compress_data_12 = compress_output_12;
404 /* Save pointer to virtual arrays */
405 coef->whole_image = coef_arrays;
407 /* Allocate and pre-zero space for dummy DCT blocks. */
409 (*cinfo->mem->alloc_large) ((j_common_ptr)cinfo, JPOOL_IMAGE,
410 C_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
411 jzero_far((void *)buffer, C_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
412 for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
413 coef->dummy_buffer[i] = buffer + i;