src/jpeg/jctrans.c

   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     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)
 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)
 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)
 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)
 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 }