jctrans.cpp (14771B)
1 /* 2 * jctrans.c 3 * 4 * Copyright (C) 1995, 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 if ( cinfo->global_state != CSTATE_START ) { 40 ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state ); 41 } 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 JQUANT_TBL ** qtblptr; 66 jpeg_component_info * incomp, * outcomp; 67 JQUANT_TBL * c_quant, * slot_quant; 68 int tblno, ci, coefi; 69 70 /* Safety check to ensure start_compress not called yet. */ 71 if ( dstinfo->global_state != CSTATE_START ) { 72 ERREXIT1( dstinfo, JERR_BAD_STATE, dstinfo->global_state ); 73 } 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 } 94 MEMCOPY( ( *qtblptr )->quantval, 95 srcinfo->quant_tbl_ptrs[tblno]->quantval, 96 SIZEOF( ( *qtblptr )->quantval ) ); 97 ( *qtblptr )->sent_table = FALSE; 98 } 99 } 100 /* Copy the source's per-component info. 101 * Note we assume jpeg_set_defaults has allocated the dest comp_info array. 102 */ 103 dstinfo->num_components = srcinfo->num_components; 104 if ( ( dstinfo->num_components < 1 ) || ( dstinfo->num_components > MAX_COMPONENTS ) ) { 105 ERREXIT2( dstinfo, JERR_COMPONENT_COUNT, dstinfo->num_components, 106 MAX_COMPONENTS ); 107 } 108 for ( ci = 0, incomp = srcinfo->comp_info, outcomp = dstinfo->comp_info; 109 ci < dstinfo->num_components; ci++, incomp++, outcomp++ ) { 110 outcomp->component_id = incomp->component_id; 111 outcomp->h_samp_factor = incomp->h_samp_factor; 112 outcomp->v_samp_factor = incomp->v_samp_factor; 113 outcomp->quant_tbl_no = incomp->quant_tbl_no; 114 /* Make sure saved quantization table for component matches the qtable 115 * slot. If not, the input file re-used this qtable slot. 116 * IJG encoder currently cannot duplicate this. 117 */ 118 tblno = outcomp->quant_tbl_no; 119 if ( ( tblno < 0 ) || ( tblno >= NUM_QUANT_TBLS ) || 120 ( srcinfo->quant_tbl_ptrs[tblno] == NULL ) ) { 121 ERREXIT1( dstinfo, JERR_NO_QUANT_TABLE, tblno ); 122 } 123 slot_quant = srcinfo->quant_tbl_ptrs[tblno]; 124 c_quant = incomp->quant_table; 125 if ( c_quant != NULL ) { 126 for ( coefi = 0; coefi < DCTSIZE2; coefi++ ) { 127 if ( c_quant->quantval[coefi] != slot_quant->quantval[coefi] ) { 128 ERREXIT1( dstinfo, JERR_MISMATCHED_QUANT_TABLE, tblno ); 129 } 130 } 131 } 132 /* Note: we do not copy the source's Huffman table assignments; 133 * instead we rely on jpeg_set_colorspace to have made a suitable choice. 134 */ 135 } 136 } 137 138 139 /* 140 * Master selection of compression modules for transcoding. 141 * This substitutes for jcinit.c's initialization of the full compressor. 142 */ 143 144 LOCAL void 145 transencode_master_selection( j_compress_ptr cinfo, 146 jvirt_barray_ptr * coef_arrays ) { 147 /* Although we don't actually use input_components for transcoding, 148 * jcmaster.c's initial_setup will complain if input_components is 0. 149 */ 150 cinfo->input_components = 1; 151 /* Initialize master control (includes parameter checking/processing) */ 152 jinit_c_master_control( cinfo, TRUE /* transcode only */ ); 153 154 /* Entropy encoding: either Huffman or arithmetic coding. */ 155 if ( cinfo->arith_code ) { 156 ERREXIT( cinfo, JERR_ARITH_NOTIMPL ); 157 } else { 158 if ( cinfo->progressive_mode ) { 159 #ifdef C_PROGRESSIVE_SUPPORTED 160 jinit_phuff_encoder( cinfo ); 161 #else 162 ERREXIT( cinfo, JERR_NOT_COMPILED ); 163 #endif 164 } else { 165 jinit_huff_encoder( cinfo ); 166 } 167 } 168 169 /* We need a special coefficient buffer controller. */ 170 transencode_coef_controller( cinfo, coef_arrays ); 171 172 jinit_marker_writer( cinfo ); 173 174 /* We can now tell the memory manager to allocate virtual arrays. */ 175 ( *cinfo->mem->realize_virt_arrays )( (j_common_ptr) cinfo ); 176 177 /* Write the datastream header (SOI) immediately. 178 * Frame and scan headers are postponed till later. 179 * This lets application insert special markers after the SOI. 180 */ 181 ( *cinfo->marker->write_file_header )( cinfo ); 182 } 183 184 185 /* 186 * The rest of this file is a special implementation of the coefficient 187 * buffer controller. This is similar to jccoefct.c, but it handles only 188 * output from presupplied virtual arrays. Furthermore, we generate any 189 * dummy padding blocks on-the-fly rather than expecting them to be present 190 * in the arrays. 191 */ 192 193 /* Private buffer controller object */ 194 195 typedef struct { 196 struct jpeg_c_coef_controller pub;/* public fields */ 197 198 JDIMENSION iMCU_row_num;/* iMCU row # within image */ 199 JDIMENSION mcu_ctr; /* counts MCUs processed in current row */ 200 int MCU_vert_offset; /* counts MCU rows within iMCU row */ 201 int MCU_rows_per_iMCU_row; /* number of such rows needed */ 202 203 /* Virtual block array for each component. */ 204 jvirt_barray_ptr * whole_image; 205 206 /* Workspace for constructing dummy blocks at right/bottom edges. */ 207 JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU]; 208 } my_coef_controller; 209 210 typedef my_coef_controller * my_coef_ptr; 211 212 213 LOCAL void 214 start_iMCU_row( j_compress_ptr cinfo ) { 215 /* Reset within-iMCU-row counters for a new row */ 216 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 217 218 /* In an interleaved scan, an MCU row is the same as an iMCU row. 219 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. 220 * But at the bottom of the image, process only what's left. 221 */ 222 if ( cinfo->comps_in_scan > 1 ) { 223 coef->MCU_rows_per_iMCU_row = 1; 224 } else { 225 if ( coef->iMCU_row_num < ( cinfo->total_iMCU_rows - 1 ) ) { 226 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; 227 } else { 228 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; 229 } 230 } 231 232 coef->mcu_ctr = 0; 233 coef->MCU_vert_offset = 0; 234 } 235 236 237 /* 238 * Initialize for a processing pass. 239 */ 240 241 METHODDEF void 242 start_pass_coef( j_compress_ptr cinfo, J_BUF_MODE pass_mode ) { 243 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 244 245 if ( pass_mode != JBUF_CRANK_DEST ) { 246 ERREXIT( cinfo, JERR_BAD_BUFFER_MODE ); 247 } 248 249 coef->iMCU_row_num = 0; 250 start_iMCU_row( cinfo ); 251 } 252 253 254 /* 255 * Process some data. 256 * We process the equivalent of one fully interleaved MCU row ("iMCU" row) 257 * per call, ie, v_samp_factor block rows for each component in the scan. 258 * The data is obtained from the virtual arrays and fed to the entropy coder. 259 * Returns TRUE if the iMCU row is completed, FALSE if suspended. 260 * 261 * NB: input_buf is ignored; it is likely to be a NULL pointer. 262 */ 263 264 METHODDEF boolean 265 compress_output( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) { 266 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 267 JDIMENSION MCU_col_num; /* index of current MCU within row */ 268 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; 269 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 270 int blkn, ci, xindex, yindex, yoffset, blockcnt; 271 JDIMENSION start_col; 272 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; 273 JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU]; 274 JBLOCKROW buffer_ptr; 275 jpeg_component_info * compptr; 276 277 /* Align the virtual buffers for the components used in this scan. */ 278 for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) { 279 compptr = cinfo->cur_comp_info[ci]; 280 buffer[ci] = ( *cinfo->mem->access_virt_barray ) 281 ( (j_common_ptr) cinfo, coef->whole_image[compptr->component_index], 282 coef->iMCU_row_num * compptr->v_samp_factor, 283 (JDIMENSION) compptr->v_samp_factor, FALSE ); 284 } 285 286 /* Loop to process one whole iMCU row */ 287 for ( yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 288 yoffset++ ) { 289 for ( MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row; 290 MCU_col_num++ ) { 291 /* Construct list of pointers to DCT blocks belonging to this MCU */ 292 blkn = 0; /* index of current DCT block within MCU */ 293 for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) { 294 compptr = cinfo->cur_comp_info[ci]; 295 start_col = MCU_col_num * compptr->MCU_width; 296 blockcnt = ( MCU_col_num < last_MCU_col ) ? compptr->MCU_width 297 : compptr->last_col_width; 298 for ( yindex = 0; yindex < compptr->MCU_height; yindex++ ) { 299 if ( ( coef->iMCU_row_num < last_iMCU_row ) || 300 ( yindex + yoffset < compptr->last_row_height ) ) { 301 /* Fill in pointers to real blocks in this row */ 302 buffer_ptr = buffer[ci][yindex + yoffset] + start_col; 303 for ( xindex = 0; xindex < blockcnt; xindex++ ) { 304 MCU_buffer[blkn++] = buffer_ptr++; 305 } 306 } else { 307 /* At bottom of image, need a whole row of dummy blocks */ 308 xindex = 0; 309 } 310 /* Fill in any dummy blocks needed in this row. 311 * Dummy blocks are filled in the same way as in jccoefct.c: 312 * all zeroes in the AC entries, DC entries equal to previous 313 * block's DC value. The init routine has already zeroed the 314 * AC entries, so we need only set the DC entries correctly. 315 */ 316 for (; xindex < compptr->MCU_width; xindex++ ) { 317 MCU_buffer[blkn] = coef->dummy_buffer[blkn]; 318 MCU_buffer[blkn][0][0] = MCU_buffer[blkn - 1][0][0]; 319 blkn++; 320 } 321 } 322 } 323 /* Try to write the MCU. */ 324 if ( !( *cinfo->entropy->encode_mcu )( cinfo, MCU_buffer ) ) { 325 /* Suspension forced; update state counters and exit */ 326 coef->MCU_vert_offset = yoffset; 327 coef->mcu_ctr = MCU_col_num; 328 return FALSE; 329 } 330 } 331 /* Completed an MCU row, but perhaps not an iMCU row */ 332 coef->mcu_ctr = 0; 333 } 334 /* Completed the iMCU row, advance counters for next one */ 335 coef->iMCU_row_num++; 336 start_iMCU_row( cinfo ); 337 return TRUE; 338 } 339 340 341 /* 342 * Initialize coefficient buffer controller. 343 * 344 * Each passed coefficient array must be the right size for that 345 * coefficient: width_in_blocks wide and height_in_blocks high, 346 * with unitheight at least v_samp_factor. 347 */ 348 349 LOCAL void 350 transencode_coef_controller( j_compress_ptr cinfo, 351 jvirt_barray_ptr * coef_arrays ) { 352 my_coef_ptr coef; 353 JBLOCKROW buffer; 354 int i; 355 356 coef = (my_coef_ptr) 357 ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE, 358 SIZEOF( my_coef_controller ) ); 359 cinfo->coef = (struct jpeg_c_coef_controller *) coef; 360 coef->pub.start_pass = start_pass_coef; 361 coef->pub.compress_data = compress_output; 362 363 /* Save pointer to virtual arrays */ 364 coef->whole_image = coef_arrays; 365 366 /* Allocate and pre-zero space for dummy DCT blocks. */ 367 buffer = (JBLOCKROW) 368 ( *cinfo->mem->alloc_large )( (j_common_ptr) cinfo, JPOOL_IMAGE, 369 C_MAX_BLOCKS_IN_MCU * SIZEOF( JBLOCK ) ); 370 jzero_far( (void FAR *) buffer, C_MAX_BLOCKS_IN_MCU * SIZEOF( JBLOCK ) ); 371 for ( i = 0; i < C_MAX_BLOCKS_IN_MCU; i++ ) { 372 coef->dummy_buffer[i] = buffer + i; 373 } 374 }