Click here to Skip to main content
Click here to Skip to main content
 
Add your own
alternative version
Go to top

Simple decoder/encoder for MNG animations

, 1 Oct 2001
CxImageMNG: the module of CxImage used to play MNG animations.
cximagemng_src.zip
CxImgLib.dsw
zlib
zlib.mak
zlib.dsp
zlib.dsw
ZLIB.DEF
jpeg
Jpeg.dsw
Jpeg.dsp
change.log
demo
demo.mak
demo.dsp
demo.dsw
demo.clw
res
demoDoc.ico
demo.ico
Toolbar.bmp
us.png
CxImage
cximage.dsp
CxImage.dsw
text2.mng
mng
mng.dsw
mng.dsp
flake.mng
text1.mng
/*
 * jctrans.c
 *
 * Copyright (C) 1995-1998, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains library routines for transcoding compression,
 * that is, writing raw DCT coefficient arrays to an output JPEG file.
 * The routines in jcapimin.c will also be needed by a transcoder.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Forward declarations */
LOCAL(void) transencode_master_selection
	JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));
LOCAL(void) transencode_coef_controller
	JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));


/*
 * Compression initialization for writing raw-coefficient data.
 * Before calling this, all parameters and a data destination must be set up.
 * Call jpeg_finish_compress() to actually write the data.
 *
 * The number of passed virtual arrays must match cinfo->num_components.
 * Note that the virtual arrays need not be filled or even realized at
 * the time write_coefficients is called; indeed, if the virtual arrays
 * were requested from this compression object's memory manager, they
 * typically will be realized during this routine and filled afterwards.
 */

GLOBAL(void)
jpeg_write_coefficients (j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays)
{
  if (cinfo->global_state != CSTATE_START)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  /* Mark all tables to be written */
  jpeg_suppress_tables(cinfo, FALSE);
  /* (Re)initialize error mgr and destination modules */
  (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
  (*cinfo->dest->init_destination) (cinfo);
  /* Perform master selection of active modules */
  transencode_master_selection(cinfo, coef_arrays);
  /* Wait for jpeg_finish_compress() call */
  cinfo->next_scanline = 0;	/* so jpeg_write_marker works */
  cinfo->global_state = CSTATE_WRCOEFS;
}


/*
 * Initialize the compression object with default parameters,
 * then copy from the source object all parameters needed for lossless
 * transcoding.  Parameters that can be varied without loss (such as
 * scan script and Huffman optimization) are left in their default states.
 */

GLOBAL(void)
jpeg_copy_critical_parameters (j_decompress_ptr srcinfo,
			       j_compress_ptr dstinfo)
{
  JQUANT_TBL ** qtblptr;
  jpeg_component_info *incomp, *outcomp;
  JQUANT_TBL *c_quant, *slot_quant;
  int tblno, ci, coefi;

  /* Safety check to ensure start_compress not called yet. */
  if (dstinfo->global_state != CSTATE_START)
    ERREXIT1(dstinfo, JERR_BAD_STATE, dstinfo->global_state);
  /* Copy fundamental image dimensions */
  dstinfo->image_width = srcinfo->image_width;
  dstinfo->image_height = srcinfo->image_height;
  dstinfo->input_components = srcinfo->num_components;
  dstinfo->in_color_space = srcinfo->jpeg_color_space;
  /* Initialize all parameters to default values */
  jpeg_set_defaults(dstinfo);
  /* jpeg_set_defaults may choose wrong colorspace, eg YCbCr if input is RGB.
   * Fix it to get the right header markers for the image colorspace.
   */
  jpeg_set_colorspace(dstinfo, srcinfo->jpeg_color_space);
  dstinfo->data_precision = srcinfo->data_precision;
  dstinfo->CCIR601_sampling = srcinfo->CCIR601_sampling;
  /* Copy the source's quantization tables. */
  for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
    if (srcinfo->quant_tbl_ptrs[tblno] != NULL) {
      qtblptr = & dstinfo->quant_tbl_ptrs[tblno];
      if (*qtblptr == NULL)
	*qtblptr = jpeg_alloc_quant_table((j_common_ptr) dstinfo);
      MEMCOPY((*qtblptr)->quantval,
	      srcinfo->quant_tbl_ptrs[tblno]->quantval,
	      SIZEOF((*qtblptr)->quantval));
      (*qtblptr)->sent_table = FALSE;
    }
  }
  /* Copy the source's per-component info.
   * Note we assume jpeg_set_defaults has allocated the dest comp_info array.
   */
  dstinfo->num_components = srcinfo->num_components;
  if (dstinfo->num_components < 1 || dstinfo->num_components > MAX_COMPONENTS)
    ERREXIT2(dstinfo, JERR_COMPONENT_COUNT, dstinfo->num_components,
	     MAX_COMPONENTS);
  for (ci = 0, incomp = srcinfo->comp_info, outcomp = dstinfo->comp_info;
       ci < dstinfo->num_components; ci++, incomp++, outcomp++) {
    outcomp->component_id = incomp->component_id;
    outcomp->h_samp_factor = incomp->h_samp_factor;
    outcomp->v_samp_factor = incomp->v_samp_factor;
    outcomp->quant_tbl_no = incomp->quant_tbl_no;
    /* Make sure saved quantization table for component matches the qtable
     * slot.  If not, the input file re-used this qtable slot.
     * IJG encoder currently cannot duplicate this.
     */
    tblno = outcomp->quant_tbl_no;
    if (tblno < 0 || tblno >= NUM_QUANT_TBLS ||
	srcinfo->quant_tbl_ptrs[tblno] == NULL)
      ERREXIT1(dstinfo, JERR_NO_QUANT_TABLE, tblno);
    slot_quant = srcinfo->quant_tbl_ptrs[tblno];
    c_quant = incomp->quant_table;
    if (c_quant != NULL) {
      for (coefi = 0; coefi < DCTSIZE2; coefi++) {
	if (c_quant->quantval[coefi] != slot_quant->quantval[coefi])
	  ERREXIT1(dstinfo, JERR_MISMATCHED_QUANT_TABLE, tblno);
      }
    }
    /* Note: we do not copy the source's Huffman table assignments;
     * instead we rely on jpeg_set_colorspace to have made a suitable choice.
     */
  }
  /* Also copy JFIF version and resolution information, if available.
   * Strictly speaking this isn't "critical" info, but it's nearly
   * always appropriate to copy it if available.  In particular,
   * if the application chooses to copy JFIF 1.02 extension markers from
   * the source file, we need to copy the version to make sure we don't
   * emit a file that has 1.02 extensions but a claimed version of 1.01.
   * We will *not*, however, copy version info from mislabeled "2.01" files.
   */
  if (srcinfo->saw_JFIF_marker) {
    if (srcinfo->JFIF_major_version == 1) {
      dstinfo->JFIF_major_version = srcinfo->JFIF_major_version;
      dstinfo->JFIF_minor_version = srcinfo->JFIF_minor_version;
    }
    dstinfo->density_unit = srcinfo->density_unit;
    dstinfo->X_density = srcinfo->X_density;
    dstinfo->Y_density = srcinfo->Y_density;
  }
}


/*
 * Master selection of compression modules for transcoding.
 * This substitutes for jcinit.c's initialization of the full compressor.
 */

LOCAL(void)
transencode_master_selection (j_compress_ptr cinfo,
			      jvirt_barray_ptr * coef_arrays)
{
  /* Although we don't actually use input_components for transcoding,
   * jcmaster.c's initial_setup will complain if input_components is 0.
   */
  cinfo->input_components = 1;
  /* Initialize master control (includes parameter checking/processing) */
  jinit_c_master_control(cinfo, TRUE /* transcode only */);

  /* Entropy encoding: either Huffman or arithmetic coding. */
  if (cinfo->arith_code) {
    ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
  } else {
    if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED
      jinit_phuff_encoder(cinfo);
#else
      ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
    } else
      jinit_huff_encoder(cinfo);
  }

  /* We need a special coefficient buffer controller. */
  transencode_coef_controller(cinfo, coef_arrays);

  jinit_marker_writer(cinfo);

  /* We can now tell the memory manager to allocate virtual arrays. */
  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);

  /* Write the datastream header (SOI, JFIF) immediately.
   * Frame and scan headers are postponed till later.
   * This lets application insert special markers after the SOI.
   */
  (*cinfo->marker->write_file_header) (cinfo);
}


/*
 * The rest of this file is a special implementation of the coefficient
 * buffer controller.  This is similar to jccoefct.c, but it handles only
 * output from presupplied virtual arrays.  Furthermore, we generate any
 * dummy padding blocks on-the-fly rather than expecting them to be present
 * in the arrays.
 */

/* Private buffer controller object */

typedef struct {
  struct jpeg_c_coef_controller pub; /* public fields */

  JDIMENSION iMCU_row_num;	/* iMCU row # within image */
  JDIMENSION mcu_ctr;		/* counts MCUs processed in current row */
  int MCU_vert_offset;		/* counts MCU rows within iMCU row */
  int MCU_rows_per_iMCU_row;	/* number of such rows needed */

  /* Virtual block array for each component. */
  jvirt_barray_ptr * whole_image;

  /* Workspace for constructing dummy blocks at right/bottom edges. */
  JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU];
} my_coef_controller;

typedef my_coef_controller * my_coef_ptr;


LOCAL(void)
start_iMCU_row (j_compress_ptr cinfo)
/* Reset within-iMCU-row counters for a new row */
{
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

  /* In an interleaved scan, an MCU row is the same as an iMCU row.
   * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
   * But at the bottom of the image, process only what's left.
   */
  if (cinfo->comps_in_scan > 1) {
    coef->MCU_rows_per_iMCU_row = 1;
  } else {
    if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
    else
      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
  }

  coef->mcu_ctr = 0;
  coef->MCU_vert_offset = 0;
}


/*
 * Initialize for a processing pass.
 */

METHODDEF(void)
start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
{
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

  if (pass_mode != JBUF_CRANK_DEST)
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

  coef->iMCU_row_num = 0;
  start_iMCU_row(cinfo);
}


/*
 * Process some data.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the scan.
 * The data is obtained from the virtual arrays and fed to the entropy coder.
 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
 *
 * NB: input_buf is ignored; it is likely to be a NULL pointer.
 */

METHODDEF(boolean)
compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
{
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
  JDIMENSION MCU_col_num;	/* index of current MCU within row */
  JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
  int blkn, ci, xindex, yindex, yoffset, blockcnt;
  JDIMENSION start_col;
  JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
  JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
  JBLOCKROW buffer_ptr;
  jpeg_component_info *compptr;

  /* Align the virtual buffers for the components used in this scan. */
  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    compptr = cinfo->cur_comp_info[ci];
    buffer[ci] = (*cinfo->mem->access_virt_barray)
      ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
       coef->iMCU_row_num * compptr->v_samp_factor,
       (JDIMENSION) compptr->v_samp_factor, FALSE);
  }

  /* Loop to process one whole iMCU row */
  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
       yoffset++) {
    for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
	 MCU_col_num++) {
      /* Construct list of pointers to DCT blocks belonging to this MCU */
      blkn = 0;			/* index of current DCT block within MCU */
      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
	compptr = cinfo->cur_comp_info[ci];
	start_col = MCU_col_num * compptr->MCU_width;
	blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
						: compptr->last_col_width;
	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
	  if (coef->iMCU_row_num < last_iMCU_row ||
	      yindex+yoffset < compptr->last_row_height) {
	    /* Fill in pointers to real blocks in this row */
	    buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
	    for (xindex = 0; xindex < blockcnt; xindex++)
	      MCU_buffer[blkn++] = buffer_ptr++;
	  } else {
	    /* At bottom of image, need a whole row of dummy blocks */
	    xindex = 0;
	  }
	  /* Fill in any dummy blocks needed in this row.
	   * Dummy blocks are filled in the same way as in jccoefct.c:
	   * all zeroes in the AC entries, DC entries equal to previous
	   * block's DC value.  The init routine has already zeroed the
	   * AC entries, so we need only set the DC entries correctly.
	   */
	  for (; xindex < compptr->MCU_width; xindex++) {
	    MCU_buffer[blkn] = coef->dummy_buffer[blkn];
	    MCU_buffer[blkn][0][0] = MCU_buffer[blkn-1][0][0];
	    blkn++;
	  }
	}
      }
      /* Try to write the MCU. */
      if (! (*cinfo->entropy->encode_mcu) (cinfo, MCU_buffer)) {
	/* Suspension forced; update state counters and exit */
	coef->MCU_vert_offset = yoffset;
	coef->mcu_ctr = MCU_col_num;
	return FALSE;
      }
    }
    /* Completed an MCU row, but perhaps not an iMCU row */
    coef->mcu_ctr = 0;
  }
  /* Completed the iMCU row, advance counters for next one */
  coef->iMCU_row_num++;
  start_iMCU_row(cinfo);
  return TRUE;
}


/*
 * Initialize coefficient buffer controller.
 *
 * Each passed coefficient array must be the right size for that
 * coefficient: width_in_blocks wide and height_in_blocks high,
 * with unitheight at least v_samp_factor.
 */

LOCAL(void)
transencode_coef_controller (j_compress_ptr cinfo,
			     jvirt_barray_ptr * coef_arrays)
{
  my_coef_ptr coef;
  JBLOCKROW buffer;
  int i;

  coef = (my_coef_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				SIZEOF(my_coef_controller));
  cinfo->coef = (struct jpeg_c_coef_controller *) coef;
  coef->pub.start_pass = start_pass_coef;
  coef->pub.compress_data = compress_output;

  /* Save pointer to virtual arrays */
  coef->whole_image = coef_arrays;

  /* Allocate and pre-zero space for dummy DCT blocks. */
  buffer = (JBLOCKROW)
    (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
  jzero_far((void FAR *) buffer, C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
  for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
    coef->dummy_buffer[i] = buffer + i;
  }
}

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Share

About the Author

No Biography provided

| Advertise | Privacy | Mobile
Web04 | 2.8.140916.1 | Last Updated 2 Oct 2001
Article Copyright 2001 by Davide Pizzolato
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid