1 /*
2  * jctrans.c
3  *
4  * Copyright (C) 1995-1998, Thomas G. Lane.
5  * Modified 2000-2013 by Guido Vollbeding.
6  * This file is part of the Independent JPEG Group's software.
7  * For conditions of distribution and use, see the accompanying README file.
8  *
9  * This file contains library routines for transcoding compression,
10  * that is, writing raw DCT coefficient arrays to an output JPEG file.
11  * The routines in jcapimin.c will also be needed by a transcoder.
12  */
13 
14 #define JPEG_INTERNALS
15 #include "jinclude.h"
16 #include "jpeglib.h"
17 
18 
19 /* Forward declarations */
20 LOCAL(void) transencode_master_selection
21 	JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));
22 LOCAL(void) transencode_coef_controller
23 	JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));
24 
25 
26 /*
27  * Compression initialization for writing raw-coefficient data.
28  * Before calling this, all parameters and a data destination must be set up.
29  * Call jpeg_finish_compress() to actually write the data.
30  *
31  * The number of passed virtual arrays must match cinfo->num_components.
32  * Note that the virtual arrays need not be filled or even realized at
33  * the time write_coefficients is called; indeed, if the virtual arrays
34  * were requested from this compression object's memory manager, they
35  * typically will be realized during this routine and filled afterwards.
36  */
37 
38 GLOBAL(void)
jpeg_write_coefficients(j_compress_ptr cinfo,jvirt_barray_ptr * coef_arrays)39 jpeg_write_coefficients (j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays)
40 {
41   if (cinfo->global_state != CSTATE_START)
42     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
43   /* Mark all tables to be written */
44   jpeg_suppress_tables(cinfo, FALSE);
45   /* (Re)initialize error mgr and destination modules */
46   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
47   (*cinfo->dest->init_destination) (cinfo);
48   /* Perform master selection of active modules */
49   transencode_master_selection(cinfo, coef_arrays);
50   /* Wait for jpeg_finish_compress() call */
51   cinfo->next_scanline = 0;	/* so jpeg_write_marker works */
52   cinfo->global_state = CSTATE_WRCOEFS;
53 }
54 
55 
56 /*
57  * Initialize the compression object with default parameters,
58  * then copy from the source object all parameters needed for lossless
59  * transcoding.  Parameters that can be varied without loss (such as
60  * scan script and Huffman optimization) are left in their default states.
61  */
62 
63 GLOBAL(void)
jpeg_copy_critical_parameters(j_decompress_ptr srcinfo,j_compress_ptr dstinfo)64 jpeg_copy_critical_parameters (j_decompress_ptr srcinfo,
65 			       j_compress_ptr dstinfo)
66 {
67   JQUANT_TBL ** qtblptr;
68   jpeg_component_info *incomp, *outcomp;
69   JQUANT_TBL *c_quant, *slot_quant;
70   int tblno, ci, coefi;
71 
72   /* Safety check to ensure start_compress not called yet. */
73   if (dstinfo->global_state != CSTATE_START)
74     ERREXIT1(dstinfo, JERR_BAD_STATE, dstinfo->global_state);
75   /* Copy fundamental image dimensions */
76   dstinfo->image_width = srcinfo->image_width;
77   dstinfo->image_height = srcinfo->image_height;
78   dstinfo->input_components = srcinfo->num_components;
79   dstinfo->in_color_space = srcinfo->jpeg_color_space;
80   dstinfo->jpeg_width = srcinfo->output_width;
81   dstinfo->jpeg_height = srcinfo->output_height;
82   dstinfo->min_DCT_h_scaled_size = srcinfo->min_DCT_h_scaled_size;
83   dstinfo->min_DCT_v_scaled_size = srcinfo->min_DCT_v_scaled_size;
84   /* Initialize all parameters to default values */
85   jpeg_set_defaults(dstinfo);
86   /* jpeg_set_defaults may choose wrong colorspace, eg YCbCr if input is RGB.
87    * Fix it to get the right header markers for the image colorspace.
88    * Note: Entropy table assignment in jpeg_set_colorspace depends
89    * on color_transform.
90    */
91   dstinfo->color_transform = srcinfo->color_transform;
92   jpeg_set_colorspace(dstinfo, srcinfo->jpeg_color_space);
93   dstinfo->data_precision = srcinfo->data_precision;
94   dstinfo->CCIR601_sampling = srcinfo->CCIR601_sampling;
95   /* Copy the source's quantization tables. */
96   for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
97     if (srcinfo->quant_tbl_ptrs[tblno] != NULL) {
98       qtblptr = & dstinfo->quant_tbl_ptrs[tblno];
99       if (*qtblptr == NULL)
100 	*qtblptr = jpeg_alloc_quant_table((j_common_ptr) dstinfo);
101       MEMCOPY((*qtblptr)->quantval,
102 	      srcinfo->quant_tbl_ptrs[tblno]->quantval,
103 	      SIZEOF((*qtblptr)->quantval));
104       (*qtblptr)->sent_table = FALSE;
105     }
106   }
107   /* Copy the source's per-component info.
108    * Note we assume jpeg_set_defaults has allocated the dest comp_info array.
109    */
110   dstinfo->num_components = srcinfo->num_components;
111   if (dstinfo->num_components < 1 || dstinfo->num_components > MAX_COMPONENTS)
112     ERREXIT2(dstinfo, JERR_COMPONENT_COUNT, dstinfo->num_components,
113 	     MAX_COMPONENTS);
114   for (ci = 0, incomp = srcinfo->comp_info, outcomp = dstinfo->comp_info;
115        ci < dstinfo->num_components; ci++, incomp++, outcomp++) {
116     outcomp->component_id = incomp->component_id;
117     outcomp->h_samp_factor = incomp->h_samp_factor;
118     outcomp->v_samp_factor = incomp->v_samp_factor;
119     outcomp->quant_tbl_no = incomp->quant_tbl_no;
120     /* Make sure saved quantization table for component matches the qtable
121      * slot.  If not, the input file re-used this qtable slot.
122      * IJG encoder currently cannot duplicate this.
123      */
124     tblno = outcomp->quant_tbl_no;
125     if (tblno < 0 || tblno >= NUM_QUANT_TBLS ||
126 	srcinfo->quant_tbl_ptrs[tblno] == NULL)
127       ERREXIT1(dstinfo, JERR_NO_QUANT_TABLE, tblno);
128     slot_quant = srcinfo->quant_tbl_ptrs[tblno];
129     c_quant = incomp->quant_table;
130     if (c_quant != NULL) {
131       for (coefi = 0; coefi < DCTSIZE2; coefi++) {
132 	if (c_quant->quantval[coefi] != slot_quant->quantval[coefi])
133 	  ERREXIT1(dstinfo, JERR_MISMATCHED_QUANT_TABLE, tblno);
134       }
135     }
136     /* Note: we do not copy the source's entropy table assignments;
137      * instead we rely on jpeg_set_colorspace to have made a suitable choice.
138      */
139   }
140   /* Also copy JFIF version and resolution information, if available.
141    * Strictly speaking this isn't "critical" info, but it's nearly
142    * always appropriate to copy it if available.  In particular,
143    * if the application chooses to copy JFIF 1.02 extension markers from
144    * the source file, we need to copy the version to make sure we don't
145    * emit a file that has 1.02 extensions but a claimed version of 1.01.
146    */
147   if (srcinfo->saw_JFIF_marker) {
148     if (srcinfo->JFIF_major_version == 1 ||
149 	srcinfo->JFIF_major_version == 2) {
150       dstinfo->JFIF_major_version = srcinfo->JFIF_major_version;
151       dstinfo->JFIF_minor_version = srcinfo->JFIF_minor_version;
152     }
153     dstinfo->density_unit = srcinfo->density_unit;
154     dstinfo->X_density = srcinfo->X_density;
155     dstinfo->Y_density = srcinfo->Y_density;
156   }
157 }
158 
159 
160 /*
161  * Master selection of compression modules for transcoding.
162  * This substitutes for jcinit.c's initialization of the full compressor.
163  */
164 
165 LOCAL(void)
transencode_master_selection(j_compress_ptr cinfo,jvirt_barray_ptr * coef_arrays)166 transencode_master_selection (j_compress_ptr cinfo,
167 			      jvirt_barray_ptr * coef_arrays)
168 {
169   /* Initialize master control (includes parameter checking/processing) */
170   jinit_c_master_control(cinfo, TRUE /* transcode only */);
171 
172   /* Entropy encoding: either Huffman or arithmetic coding. */
173   if (cinfo->arith_code)
174     jinit_arith_encoder(cinfo);
175   else {
176     jinit_huff_encoder(cinfo);
177   }
178 
179   /* We need a special coefficient buffer controller. */
180   transencode_coef_controller(cinfo, coef_arrays);
181 
182   jinit_marker_writer(cinfo);
183 
184   /* We can now tell the memory manager to allocate virtual arrays. */
185   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
186 
187   /* Write the datastream header (SOI, JFIF) immediately.
188    * Frame and scan headers are postponed till later.
189    * This lets application insert special markers after the SOI.
190    */
191   (*cinfo->marker->write_file_header) (cinfo);
192 }
193 
194 
195 /*
196  * The rest of this file is a special implementation of the coefficient
197  * buffer controller.  This is similar to jccoefct.c, but it handles only
198  * output from presupplied virtual arrays.  Furthermore, we generate any
199  * dummy padding blocks on-the-fly rather than expecting them to be present
200  * in the arrays.
201  */
202 
203 /* Private buffer controller object */
204 
205 typedef struct {
206   struct jpeg_c_coef_controller pub; /* public fields */
207 
208   JDIMENSION iMCU_row_num;	/* iMCU row # within image */
209   JDIMENSION mcu_ctr;		/* counts MCUs processed in current row */
210   int MCU_vert_offset;		/* counts MCU rows within iMCU row */
211   int MCU_rows_per_iMCU_row;	/* number of such rows needed */
212 
213   /* Virtual block array for each component. */
214   jvirt_barray_ptr * whole_image;
215 
216   /* Workspace for constructing dummy blocks at right/bottom edges. */
217   JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU];
218 } my_coef_controller;
219 
220 typedef my_coef_controller * my_coef_ptr;
221 
222 
223 LOCAL(void)
start_iMCU_row(j_compress_ptr cinfo)224 start_iMCU_row (j_compress_ptr cinfo)
225 /* Reset within-iMCU-row counters for a new row */
226 {
227   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
228 
229   /* In an interleaved scan, an MCU row is the same as an iMCU row.
230    * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
231    * But at the bottom of the image, process only what's left.
232    */
233   if (cinfo->comps_in_scan > 1) {
234     coef->MCU_rows_per_iMCU_row = 1;
235   } else {
236     if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
237       coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
238     else
239       coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
240   }
241 
242   coef->mcu_ctr = 0;
243   coef->MCU_vert_offset = 0;
244 }
245 
246 
247 /*
248  * Initialize for a processing pass.
249  */
250 
251 METHODDEF(void)
start_pass_coef(j_compress_ptr cinfo,J_BUF_MODE pass_mode)252 start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
253 {
254   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
255 
256   if (pass_mode != JBUF_CRANK_DEST)
257     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
258 
259   coef->iMCU_row_num = 0;
260   start_iMCU_row(cinfo);
261 }
262 
263 
264 /*
265  * Process some data.
266  * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
267  * per call, ie, v_samp_factor block rows for each component in the scan.
268  * The data is obtained from the virtual arrays and fed to the entropy coder.
269  * Returns TRUE if the iMCU row is completed, FALSE if suspended.
270  *
271  * NB: input_buf is ignored; it is likely to be a NULL pointer.
272  */
273 
274 METHODDEF(boolean)
compress_output(j_compress_ptr cinfo,JSAMPIMAGE input_buf)275 compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
276 {
277   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
278   JDIMENSION MCU_col_num;	/* index of current MCU within row */
279   JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
280   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
281   int blkn, ci, xindex, yindex, yoffset, blockcnt;
282   JDIMENSION start_col;
283   JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
284   JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
285   JBLOCKROW buffer_ptr;
286   jpeg_component_info *compptr;
287 
288   /* Align the virtual buffers for the components used in this scan. */
289   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
290     compptr = cinfo->cur_comp_info[ci];
291     buffer[ci] = (*cinfo->mem->access_virt_barray)
292       ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
293        coef->iMCU_row_num * compptr->v_samp_factor,
294        (JDIMENSION) compptr->v_samp_factor, FALSE);
295   }
296 
297   /* Loop to process one whole iMCU row */
298   for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
299        yoffset++) {
300     for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
301 	 MCU_col_num++) {
302       /* Construct list of pointers to DCT blocks belonging to this MCU */
303       blkn = 0;			/* index of current DCT block within MCU */
304       for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
305 	compptr = cinfo->cur_comp_info[ci];
306 	start_col = MCU_col_num * compptr->MCU_width;
307 	blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
308 						: compptr->last_col_width;
309 	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
310 	  if (coef->iMCU_row_num < last_iMCU_row ||
311 	      yindex+yoffset < compptr->last_row_height) {
312 	    /* Fill in pointers to real blocks in this row */
313 	    buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
314 	    for (xindex = 0; xindex < blockcnt; xindex++)
315 	      MCU_buffer[blkn++] = buffer_ptr++;
316 	  } else {
317 	    /* At bottom of image, need a whole row of dummy blocks */
318 	    xindex = 0;
319 	  }
320 	  /* Fill in any dummy blocks needed in this row.
321 	   * Dummy blocks are filled in the same way as in jccoefct.c:
322 	   * all zeroes in the AC entries, DC entries equal to previous
323 	   * block's DC value.  The init routine has already zeroed the
324 	   * AC entries, so we need only set the DC entries correctly.
325 	   */
326 	  for (; xindex < compptr->MCU_width; xindex++) {
327 	    MCU_buffer[blkn] = coef->dummy_buffer[blkn];
328 	    MCU_buffer[blkn][0][0] = MCU_buffer[blkn-1][0][0];
329 	    blkn++;
330 	  }
331 	}
332       }
333       /* Try to write the MCU. */
334       if (! (*cinfo->entropy->encode_mcu) (cinfo, MCU_buffer)) {
335 	/* Suspension forced; update state counters and exit */
336 	coef->MCU_vert_offset = yoffset;
337 	coef->mcu_ctr = MCU_col_num;
338 	return FALSE;
339       }
340     }
341     /* Completed an MCU row, but perhaps not an iMCU row */
342     coef->mcu_ctr = 0;
343   }
344   /* Completed the iMCU row, advance counters for next one */
345   coef->iMCU_row_num++;
346   start_iMCU_row(cinfo);
347   return TRUE;
348 }
349 
350 
351 /*
352  * Initialize coefficient buffer controller.
353  *
354  * Each passed coefficient array must be the right size for that
355  * coefficient: width_in_blocks wide and height_in_blocks high,
356  * with unitheight at least v_samp_factor.
357  */
358 
359 LOCAL(void)
transencode_coef_controller(j_compress_ptr cinfo,jvirt_barray_ptr * coef_arrays)360 transencode_coef_controller (j_compress_ptr cinfo,
361 			     jvirt_barray_ptr * coef_arrays)
362 {
363   my_coef_ptr coef;
364   JBLOCKROW buffer;
365   int i;
366 
367   coef = (my_coef_ptr)
368     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
369 				SIZEOF(my_coef_controller));
370   cinfo->coef = &coef->pub;
371   coef->pub.start_pass = start_pass_coef;
372   coef->pub.compress_data = compress_output;
373 
374   /* Save pointer to virtual arrays */
375   coef->whole_image = coef_arrays;
376 
377   /* Allocate and pre-zero space for dummy DCT blocks. */
378   buffer = (JBLOCKROW)
379     (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
380 				C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
381   FMEMZERO((void FAR *) buffer, C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
382   for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
383     coef->dummy_buffer[i] = buffer + i;
384   }
385 }
386