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 }