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)
jpeg_write_coefficients(j_compress_ptr cinfo,jvirt_barray_ptr * coef_arrays)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)
jpeg_copy_critical_parameters(j_decompress_ptr srcinfo,j_compress_ptr dstinfo)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)
transencode_master_selection(j_compress_ptr cinfo,jvirt_barray_ptr * coef_arrays)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     if (cinfo->progressive_mode) {
173 #ifdef C_PROGRESSIVE_SUPPORTED
174       jinit_phuff_encoder(cinfo);
175 #else
176       ERREXIT(cinfo, JERR_NOT_COMPILED);
177 #endif
178     } else
179       jinit_huff_encoder(cinfo);
180   }
181 
182   /* We need a special coefficient buffer controller. */
183   transencode_coef_controller(cinfo, coef_arrays);
184 
185   jinit_marker_writer(cinfo);
186 
187   /* We can now tell the memory manager to allocate virtual arrays. */
188   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
189 
190   /* Write the datastream header (SOI, JFIF) immediately.
191    * Frame and scan headers are postponed till later.
192    * This lets application insert special markers after the SOI.
193    */
194   (*cinfo->marker->write_file_header) (cinfo);
195 }
196 
197 
198 /*
199  * The rest of this file is a special implementation of the coefficient
200  * buffer controller.  This is similar to jccoefct.c, but it handles only
201  * output from presupplied virtual arrays.  Furthermore, we generate any
202  * dummy padding blocks on-the-fly rather than expecting them to be present
203  * in the arrays.
204  */
205 
206 /* Private buffer controller object */
207 
208 typedef struct {
209   struct jpeg_c_coef_controller pub; /* public fields */
210 
211   JDIMENSION iMCU_row_num;	/* iMCU row # within image */
212   JDIMENSION mcu_ctr;		/* counts MCUs processed in current row */
213   int MCU_vert_offset;		/* counts MCU rows within iMCU row */
214   int MCU_rows_per_iMCU_row;	/* number of such rows needed */
215 
216   /* Virtual block array for each component. */
217   jvirt_barray_ptr * whole_image;
218 
219   /* Workspace for constructing dummy blocks at right/bottom edges. */
220   JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU];
221 } my_coef_controller;
222 
223 typedef my_coef_controller * my_coef_ptr;
224 
225 
226 LOCAL(void)
start_iMCU_row(j_compress_ptr cinfo)227 start_iMCU_row (j_compress_ptr cinfo)
228 /* Reset within-iMCU-row counters for a new row */
229 {
230   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
231 
232   /* In an interleaved scan, an MCU row is the same as an iMCU row.
233    * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
234    * But at the bottom of the image, process only what's left.
235    */
236   if (cinfo->comps_in_scan > 1) {
237     coef->MCU_rows_per_iMCU_row = 1;
238   } else {
239     if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
240       coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
241     else
242       coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
243   }
244 
245   coef->mcu_ctr = 0;
246   coef->MCU_vert_offset = 0;
247 }
248 
249 
250 /*
251  * Initialize for a processing pass.
252  */
253 
254 METHODDEF(void)
start_pass_coef(j_compress_ptr cinfo,J_BUF_MODE pass_mode)255 start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
256 {
257   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
258 
259   if (pass_mode != JBUF_CRANK_DEST)
260     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
261 
262   coef->iMCU_row_num = 0;
263   start_iMCU_row(cinfo);
264 }
265 
266 
267 /*
268  * Process some data.
269  * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
270  * per call, ie, v_samp_factor block rows for each component in the scan.
271  * The data is obtained from the virtual arrays and fed to the entropy coder.
272  * Returns TRUE if the iMCU row is completed, FALSE if suspended.
273  *
274  * NB: input_buf is ignored; it is likely to be a NULL pointer.
275  */
276 
277 METHODDEF(boolean)
compress_output(j_compress_ptr cinfo,JSAMPIMAGE input_buf)278 compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
279 {
280   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
281   JDIMENSION MCU_col_num;	/* index of current MCU within row */
282   JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
283   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
284   int blkn, ci, xindex, yindex, yoffset, blockcnt;
285   JDIMENSION start_col;
286   JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
287   JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
288   JBLOCKROW buffer_ptr;
289   jpeg_component_info *compptr;
290 
291   /* Align the virtual buffers for the components used in this scan. */
292   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
293     compptr = cinfo->cur_comp_info[ci];
294     buffer[ci] = (*cinfo->mem->access_virt_barray)
295       ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
296        coef->iMCU_row_num * compptr->v_samp_factor,
297        (JDIMENSION) compptr->v_samp_factor, FALSE);
298   }
299 
300   /* Loop to process one whole iMCU row */
301   for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
302        yoffset++) {
303     for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
304 	 MCU_col_num++) {
305       /* Construct list of pointers to DCT blocks belonging to this MCU */
306       blkn = 0;			/* index of current DCT block within MCU */
307       for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
308 	compptr = cinfo->cur_comp_info[ci];
309 	start_col = MCU_col_num * compptr->MCU_width;
310 	blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
311 						: compptr->last_col_width;
312 	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
313 	  if (coef->iMCU_row_num < last_iMCU_row ||
314 	      yindex+yoffset < compptr->last_row_height) {
315 	    /* Fill in pointers to real blocks in this row */
316 	    buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
317 	    for (xindex = 0; xindex < blockcnt; xindex++)
318 	      MCU_buffer[blkn++] = buffer_ptr++;
319 	  } else {
320 	    /* At bottom of image, need a whole row of dummy blocks */
321 	    xindex = 0;
322 	  }
323 	  /* Fill in any dummy blocks needed in this row.
324 	   * Dummy blocks are filled in the same way as in jccoefct.c:
325 	   * all zeroes in the AC entries, DC entries equal to previous
326 	   * block's DC value.  The init routine has already zeroed the
327 	   * AC entries, so we need only set the DC entries correctly.
328 	   */
329 	  for (; xindex < compptr->MCU_width; xindex++) {
330 	    MCU_buffer[blkn] = coef->dummy_buffer[blkn];
331 	    MCU_buffer[blkn][0][0] = MCU_buffer[blkn-1][0][0];
332 	    blkn++;
333 	  }
334 	}
335       }
336       /* Try to write the MCU. */
337       if (! (*cinfo->entropy->encode_mcu) (cinfo, MCU_buffer)) {
338 	/* Suspension forced; update state counters and exit */
339 	coef->MCU_vert_offset = yoffset;
340 	coef->mcu_ctr = MCU_col_num;
341 	return FALSE;
342       }
343     }
344     /* Completed an MCU row, but perhaps not an iMCU row */
345     coef->mcu_ctr = 0;
346   }
347   /* Completed the iMCU row, advance counters for next one */
348   coef->iMCU_row_num++;
349   start_iMCU_row(cinfo);
350   return TRUE;
351 }
352 
353 
354 /*
355  * Initialize coefficient buffer controller.
356  *
357  * Each passed coefficient array must be the right size for that
358  * coefficient: width_in_blocks wide and height_in_blocks high,
359  * with unitheight at least v_samp_factor.
360  */
361 
362 LOCAL(void)
transencode_coef_controller(j_compress_ptr cinfo,jvirt_barray_ptr * coef_arrays)363 transencode_coef_controller (j_compress_ptr cinfo,
364 			     jvirt_barray_ptr * coef_arrays)
365 {
366   my_coef_ptr coef;
367   JBLOCKROW buffer;
368   int i;
369 
370   coef = (my_coef_ptr)
371     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
372 				SIZEOF(my_coef_controller));
373   cinfo->coef = (struct jpeg_c_coef_controller *) coef;
374   coef->pub.start_pass = start_pass_coef;
375   coef->pub.compress_data = compress_output;
376 
377   /* Save pointer to virtual arrays */
378   coef->whole_image = coef_arrays;
379 
380   /* Allocate and pre-zero space for dummy DCT blocks. */
381   buffer = (JBLOCKROW)
382     (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
383 				C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
384   jzero_far((void FAR *) buffer, C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
385   for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
386     coef->dummy_buffer[i] = buffer + i;
387   }
388 }
389