source: trunk/libjpeg/jctrans.c @ 283

Last change on this file since 283 was 283, checked in by rbri, 12 years ago

JPEG plugin: libjpeg updated to version 7

File size: 13.9 KB
Line 
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 */
19LOCAL(void) transencode_master_selection
20        JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));
21LOCAL(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
37GLOBAL(void)
38jpeg_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
62GLOBAL(void)
63jpeg_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
157LOCAL(void)
158transencode_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    jinit_arith_encoder(cinfo);
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
201typedef 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
216typedef my_coef_controller * my_coef_ptr;
217
218
219LOCAL(void)
220start_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
247METHODDEF(void)
248start_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
270METHODDEF(boolean)
271compress_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
355LOCAL(void)
356transencode_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}
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