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  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. }
  389.