ref: bea7b7bf8ccbc2bc41906517079e76fcfb31cb5a
dir: /code/jpeg-6/jctrans.c/
/*
* jctrans.c
*
* Copyright (C) 1995, 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.
*/
}
}
/*
* 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) 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;
}
}