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
