1// Copyright 2012 Google Inc. All Rights Reserved. 2// 3// This code is licensed under the same terms as WebM: 4// Software License Agreement: http://www.webmproject.org/license/software/ 5// Additional IP Rights Grant: http://www.webmproject.org/license/additional/ 6// ----------------------------------------------------------------------------- 7// 8// main entry for the decoder 9// 10// Authors: Vikas Arora (vikaas.arora@gmail.com) 11// Jyrki Alakuijala (jyrki@google.com) 12 13#include <stdio.h> 14#include <stdlib.h> 15#include "./vp8li.h" 16#include "../dsp/lossless.h" 17#include "../dsp/yuv.h" 18#include "../utils/huffman.h" 19#include "../utils/utils.h" 20 21#if defined(__cplusplus) || defined(c_plusplus) 22extern "C" { 23#endif 24 25#define NUM_ARGB_CACHE_ROWS 16 26 27static const int kCodeLengthLiterals = 16; 28static const int kCodeLengthRepeatCode = 16; 29static const int kCodeLengthExtraBits[3] = { 2, 3, 7 }; 30static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 }; 31 32// ----------------------------------------------------------------------------- 33// Five Huffman codes are used at each meta code: 34// 1. green + length prefix codes + color cache codes, 35// 2. alpha, 36// 3. red, 37// 4. blue, and, 38// 5. distance prefix codes. 39typedef enum { 40 GREEN = 0, 41 RED = 1, 42 BLUE = 2, 43 ALPHA = 3, 44 DIST = 4 45} HuffIndex; 46 47static const uint16_t kAlphabetSize[HUFFMAN_CODES_PER_META_CODE] = { 48 NUM_LITERAL_CODES + NUM_LENGTH_CODES, 49 NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES, 50 NUM_DISTANCE_CODES 51}; 52 53 54#define NUM_CODE_LENGTH_CODES 19 55static const uint8_t kCodeLengthCodeOrder[NUM_CODE_LENGTH_CODES] = { 56 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 57}; 58 59#define CODE_TO_PLANE_CODES 120 60static const uint8_t code_to_plane_lut[CODE_TO_PLANE_CODES] = { 61 0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a, 62 0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a, 63 0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b, 64 0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03, 65 0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c, 66 0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e, 67 0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b, 68 0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f, 69 0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b, 70 0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41, 71 0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f, 72 0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70 73}; 74 75static int DecodeImageStream(int xsize, int ysize, 76 int is_level0, 77 VP8LDecoder* const dec, 78 uint32_t** const decoded_data); 79 80//------------------------------------------------------------------------------ 81 82int VP8LCheckSignature(const uint8_t* const data, size_t size) { 83 return (size >= 1) && (data[0] == VP8L_MAGIC_BYTE); 84} 85 86static int ReadImageInfo(VP8LBitReader* const br, 87 int* const width, int* const height, 88 int* const has_alpha) { 89 const uint8_t signature = VP8LReadBits(br, 8); 90 if (!VP8LCheckSignature(&signature, 1)) { 91 return 0; 92 } 93 *width = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1; 94 *height = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1; 95 *has_alpha = VP8LReadBits(br, 1); 96 VP8LReadBits(br, VP8L_VERSION_BITS); // Read/ignore the version number. 97 return 1; 98} 99 100int VP8LGetInfo(const uint8_t* data, size_t data_size, 101 int* const width, int* const height, int* const has_alpha) { 102 if (data == NULL || data_size < VP8L_FRAME_HEADER_SIZE) { 103 return 0; // not enough data 104 } else { 105 int w, h, a; 106 VP8LBitReader br; 107 VP8LInitBitReader(&br, data, data_size); 108 if (!ReadImageInfo(&br, &w, &h, &a)) { 109 return 0; 110 } 111 if (width != NULL) *width = w; 112 if (height != NULL) *height = h; 113 if (has_alpha != NULL) *has_alpha = a; 114 return 1; 115 } 116} 117 118//------------------------------------------------------------------------------ 119 120static WEBP_INLINE int GetCopyDistance(int distance_symbol, 121 VP8LBitReader* const br) { 122 int extra_bits, offset; 123 if (distance_symbol < 4) { 124 return distance_symbol + 1; 125 } 126 extra_bits = (distance_symbol - 2) >> 1; 127 offset = (2 + (distance_symbol & 1)) << extra_bits; 128 return offset + VP8LReadBits(br, extra_bits) + 1; 129} 130 131static WEBP_INLINE int GetCopyLength(int length_symbol, 132 VP8LBitReader* const br) { 133 // Length and distance prefixes are encoded the same way. 134 return GetCopyDistance(length_symbol, br); 135} 136 137static WEBP_INLINE int PlaneCodeToDistance(int xsize, int plane_code) { 138 if (plane_code > CODE_TO_PLANE_CODES) { 139 return plane_code - CODE_TO_PLANE_CODES; 140 } else { 141 const int dist_code = code_to_plane_lut[plane_code - 1]; 142 const int yoffset = dist_code >> 4; 143 const int xoffset = 8 - (dist_code & 0xf); 144 const int dist = yoffset * xsize + xoffset; 145 return (dist >= 1) ? dist : 1; 146 } 147} 148 149//------------------------------------------------------------------------------ 150// Decodes the next Huffman code from bit-stream. 151// FillBitWindow(br) needs to be called at minimum every second call 152// to ReadSymbolUnsafe. 153static int ReadSymbolUnsafe(const HuffmanTree* tree, VP8LBitReader* const br) { 154 const HuffmanTreeNode* node = tree->root_; 155 assert(node != NULL); 156 while (!HuffmanTreeNodeIsLeaf(node)) { 157 node = HuffmanTreeNextNode(node, VP8LReadOneBitUnsafe(br)); 158 } 159 return node->symbol_; 160} 161 162static WEBP_INLINE int ReadSymbol(const HuffmanTree* tree, 163 VP8LBitReader* const br) { 164 const int read_safe = (br->pos_ + 8 > br->len_); 165 if (!read_safe) { 166 return ReadSymbolUnsafe(tree, br); 167 } else { 168 const HuffmanTreeNode* node = tree->root_; 169 assert(node != NULL); 170 while (!HuffmanTreeNodeIsLeaf(node)) { 171 node = HuffmanTreeNextNode(node, VP8LReadOneBit(br)); 172 } 173 return node->symbol_; 174 } 175} 176 177static int ReadHuffmanCodeLengths( 178 VP8LDecoder* const dec, const int* const code_length_code_lengths, 179 int num_symbols, int* const code_lengths) { 180 int ok = 0; 181 VP8LBitReader* const br = &dec->br_; 182 int symbol; 183 int max_symbol; 184 int prev_code_len = DEFAULT_CODE_LENGTH; 185 HuffmanTree tree; 186 187 if (!HuffmanTreeBuildImplicit(&tree, code_length_code_lengths, 188 NUM_CODE_LENGTH_CODES)) { 189 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 190 return 0; 191 } 192 193 if (VP8LReadBits(br, 1)) { // use length 194 const int length_nbits = 2 + 2 * VP8LReadBits(br, 3); 195 max_symbol = 2 + VP8LReadBits(br, length_nbits); 196 if (max_symbol > num_symbols) { 197 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 198 goto End; 199 } 200 } else { 201 max_symbol = num_symbols; 202 } 203 204 symbol = 0; 205 while (symbol < num_symbols) { 206 int code_len; 207 if (max_symbol-- == 0) break; 208 VP8LFillBitWindow(br); 209 code_len = ReadSymbol(&tree, br); 210 if (code_len < kCodeLengthLiterals) { 211 code_lengths[symbol++] = code_len; 212 if (code_len != 0) prev_code_len = code_len; 213 } else { 214 const int use_prev = (code_len == kCodeLengthRepeatCode); 215 const int slot = code_len - kCodeLengthLiterals; 216 const int extra_bits = kCodeLengthExtraBits[slot]; 217 const int repeat_offset = kCodeLengthRepeatOffsets[slot]; 218 int repeat = VP8LReadBits(br, extra_bits) + repeat_offset; 219 if (symbol + repeat > num_symbols) { 220 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 221 goto End; 222 } else { 223 const int length = use_prev ? prev_code_len : 0; 224 while (repeat-- > 0) code_lengths[symbol++] = length; 225 } 226 } 227 } 228 ok = 1; 229 230 End: 231 HuffmanTreeRelease(&tree); 232 return ok; 233} 234 235static int ReadHuffmanCode(int alphabet_size, VP8LDecoder* const dec, 236 HuffmanTree* const tree) { 237 int ok = 0; 238 VP8LBitReader* const br = &dec->br_; 239 const int simple_code = VP8LReadBits(br, 1); 240 241 if (simple_code) { // Read symbols, codes & code lengths directly. 242 int symbols[2]; 243 int codes[2]; 244 int code_lengths[2]; 245 const int num_symbols = VP8LReadBits(br, 1) + 1; 246 const int first_symbol_len_code = VP8LReadBits(br, 1); 247 // The first code is either 1 bit or 8 bit code. 248 symbols[0] = VP8LReadBits(br, (first_symbol_len_code == 0) ? 1 : 8); 249 codes[0] = 0; 250 code_lengths[0] = num_symbols - 1; 251 // The second code (if present), is always 8 bit long. 252 if (num_symbols == 2) { 253 symbols[1] = VP8LReadBits(br, 8); 254 codes[1] = 1; 255 code_lengths[1] = num_symbols - 1; 256 } 257 ok = HuffmanTreeBuildExplicit(tree, code_lengths, codes, symbols, 258 alphabet_size, num_symbols); 259 } else { // Decode Huffman-coded code lengths. 260 int* code_lengths = NULL; 261 int i; 262 int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 }; 263 const int num_codes = VP8LReadBits(br, 4) + 4; 264 if (num_codes > NUM_CODE_LENGTH_CODES) { 265 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 266 return 0; 267 } 268 269 code_lengths = 270 (int*)WebPSafeCalloc((uint64_t)alphabet_size, sizeof(*code_lengths)); 271 if (code_lengths == NULL) { 272 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 273 return 0; 274 } 275 276 for (i = 0; i < num_codes; ++i) { 277 code_length_code_lengths[kCodeLengthCodeOrder[i]] = VP8LReadBits(br, 3); 278 } 279 ok = ReadHuffmanCodeLengths(dec, code_length_code_lengths, alphabet_size, 280 code_lengths); 281 if (ok) { 282 ok = HuffmanTreeBuildImplicit(tree, code_lengths, alphabet_size); 283 } 284 free(code_lengths); 285 } 286 ok = ok && !br->error_; 287 if (!ok) { 288 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 289 return 0; 290 } 291 return 1; 292} 293 294static void DeleteHtreeGroups(HTreeGroup* htree_groups, int num_htree_groups) { 295 if (htree_groups != NULL) { 296 int i, j; 297 for (i = 0; i < num_htree_groups; ++i) { 298 HuffmanTree* const htrees = htree_groups[i].htrees_; 299 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { 300 HuffmanTreeRelease(&htrees[j]); 301 } 302 } 303 free(htree_groups); 304 } 305} 306 307static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize, 308 int color_cache_bits, int allow_recursion) { 309 int i, j; 310 VP8LBitReader* const br = &dec->br_; 311 VP8LMetadata* const hdr = &dec->hdr_; 312 uint32_t* huffman_image = NULL; 313 HTreeGroup* htree_groups = NULL; 314 int num_htree_groups = 1; 315 316 if (allow_recursion && VP8LReadBits(br, 1)) { 317 // use meta Huffman codes. 318 const int huffman_precision = VP8LReadBits(br, 3) + 2; 319 const int huffman_xsize = VP8LSubSampleSize(xsize, huffman_precision); 320 const int huffman_ysize = VP8LSubSampleSize(ysize, huffman_precision); 321 const int huffman_pixs = huffman_xsize * huffman_ysize; 322 if (!DecodeImageStream(huffman_xsize, huffman_ysize, 0, dec, 323 &huffman_image)) { 324 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 325 goto Error; 326 } 327 hdr->huffman_subsample_bits_ = huffman_precision; 328 for (i = 0; i < huffman_pixs; ++i) { 329 // The huffman data is stored in red and green bytes. 330 const int index = (huffman_image[i] >> 8) & 0xffff; 331 huffman_image[i] = index; 332 if (index >= num_htree_groups) { 333 num_htree_groups = index + 1; 334 } 335 } 336 } 337 338 if (br->error_) goto Error; 339 340 assert(num_htree_groups <= 0x10000); 341 htree_groups = 342 (HTreeGroup*)WebPSafeCalloc((uint64_t)num_htree_groups, 343 sizeof(*htree_groups)); 344 if (htree_groups == NULL) { 345 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 346 goto Error; 347 } 348 349 for (i = 0; i < num_htree_groups; ++i) { 350 HuffmanTree* const htrees = htree_groups[i].htrees_; 351 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { 352 int alphabet_size = kAlphabetSize[j]; 353 if (j == 0 && color_cache_bits > 0) { 354 alphabet_size += 1 << color_cache_bits; 355 } 356 if (!ReadHuffmanCode(alphabet_size, dec, htrees + j)) goto Error; 357 } 358 } 359 360 // All OK. Finalize pointers and return. 361 hdr->huffman_image_ = huffman_image; 362 hdr->num_htree_groups_ = num_htree_groups; 363 hdr->htree_groups_ = htree_groups; 364 return 1; 365 366 Error: 367 free(huffman_image); 368 DeleteHtreeGroups(htree_groups, num_htree_groups); 369 return 0; 370} 371 372//------------------------------------------------------------------------------ 373// Scaling. 374 375static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) { 376 const int num_channels = 4; 377 const int in_width = io->mb_w; 378 const int out_width = io->scaled_width; 379 const int in_height = io->mb_h; 380 const int out_height = io->scaled_height; 381 const uint64_t work_size = 2 * num_channels * (uint64_t)out_width; 382 int32_t* work; // Rescaler work area. 383 const uint64_t scaled_data_size = num_channels * (uint64_t)out_width; 384 uint32_t* scaled_data; // Temporary storage for scaled BGRA data. 385 const uint64_t memory_size = sizeof(*dec->rescaler) + 386 work_size * sizeof(*work) + 387 scaled_data_size * sizeof(*scaled_data); 388 uint8_t* memory = (uint8_t*)WebPSafeCalloc(memory_size, sizeof(*memory)); 389 if (memory == NULL) { 390 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 391 return 0; 392 } 393 assert(dec->rescaler_memory == NULL); 394 dec->rescaler_memory = memory; 395 396 dec->rescaler = (WebPRescaler*)memory; 397 memory += sizeof(*dec->rescaler); 398 work = (int32_t*)memory; 399 memory += work_size * sizeof(*work); 400 scaled_data = (uint32_t*)memory; 401 402 WebPRescalerInit(dec->rescaler, in_width, in_height, (uint8_t*)scaled_data, 403 out_width, out_height, 0, num_channels, 404 in_width, out_width, in_height, out_height, work); 405 return 1; 406} 407 408//------------------------------------------------------------------------------ 409// Export to ARGB 410 411// We have special "export" function since we need to convert from BGRA 412static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace, 413 int rgba_stride, uint8_t* const rgba) { 414 const uint32_t* const src = (const uint32_t*)rescaler->dst; 415 const int dst_width = rescaler->dst_width; 416 int num_lines_out = 0; 417 while (WebPRescalerHasPendingOutput(rescaler)) { 418 uint8_t* const dst = rgba + num_lines_out * rgba_stride; 419 WebPRescalerExportRow(rescaler); 420 VP8LConvertFromBGRA(src, dst_width, colorspace, dst); 421 ++num_lines_out; 422 } 423 return num_lines_out; 424} 425 426// Emit scaled rows. 427static int EmitRescaledRows(const VP8LDecoder* const dec, 428 const uint32_t* const data, int in_stride, int mb_h, 429 uint8_t* const out, int out_stride) { 430 const WEBP_CSP_MODE colorspace = dec->output_->colorspace; 431 const uint8_t* const in = (const uint8_t*)data; 432 int num_lines_in = 0; 433 int num_lines_out = 0; 434 while (num_lines_in < mb_h) { 435 const uint8_t* const row_in = in + num_lines_in * in_stride; 436 uint8_t* const row_out = out + num_lines_out * out_stride; 437 num_lines_in += WebPRescalerImport(dec->rescaler, mb_h - num_lines_in, 438 row_in, in_stride); 439 num_lines_out += Export(dec->rescaler, colorspace, out_stride, row_out); 440 } 441 return num_lines_out; 442} 443 444// Emit rows without any scaling. 445static int EmitRows(WEBP_CSP_MODE colorspace, 446 const uint32_t* const data, int in_stride, 447 int mb_w, int mb_h, 448 uint8_t* const out, int out_stride) { 449 int lines = mb_h; 450 const uint8_t* row_in = (const uint8_t*)data; 451 uint8_t* row_out = out; 452 while (lines-- > 0) { 453 VP8LConvertFromBGRA((const uint32_t*)row_in, mb_w, colorspace, row_out); 454 row_in += in_stride; 455 row_out += out_stride; 456 } 457 return mb_h; // Num rows out == num rows in. 458} 459 460//------------------------------------------------------------------------------ 461// Export to YUVA 462 463static void ConvertToYUVA(const uint32_t* const src, int width, int y_pos, 464 const WebPDecBuffer* const output) { 465 const WebPYUVABuffer* const buf = &output->u.YUVA; 466 // first, the luma plane 467 { 468 int i; 469 uint8_t* const y = buf->y + y_pos * buf->y_stride; 470 for (i = 0; i < width; ++i) { 471 const uint32_t p = src[i]; 472 y[i] = VP8RGBToY((p >> 16) & 0xff, (p >> 8) & 0xff, (p >> 0) & 0xff); 473 } 474 } 475 476 // then U/V planes 477 { 478 uint8_t* const u = buf->u + (y_pos >> 1) * buf->u_stride; 479 uint8_t* const v = buf->v + (y_pos >> 1) * buf->v_stride; 480 const int uv_width = width >> 1; 481 int i; 482 for (i = 0; i < uv_width; ++i) { 483 const uint32_t v0 = src[2 * i + 0]; 484 const uint32_t v1 = src[2 * i + 1]; 485 // VP8RGBToU/V expects four accumulated pixels. Hence we need to 486 // scale r/g/b value by a factor 2. We just shift v0/v1 one bit less. 487 const int r = ((v0 >> 15) & 0x1fe) + ((v1 >> 15) & 0x1fe); 488 const int g = ((v0 >> 7) & 0x1fe) + ((v1 >> 7) & 0x1fe); 489 const int b = ((v0 << 1) & 0x1fe) + ((v1 << 1) & 0x1fe); 490 if (!(y_pos & 1)) { // even lines: store values 491 u[i] = VP8RGBToU(r, g, b); 492 v[i] = VP8RGBToV(r, g, b); 493 } else { // odd lines: average with previous values 494 const int tmp_u = VP8RGBToU(r, g, b); 495 const int tmp_v = VP8RGBToV(r, g, b); 496 // Approximated average-of-four. But it's an acceptable diff. 497 u[i] = (u[i] + tmp_u + 1) >> 1; 498 v[i] = (v[i] + tmp_v + 1) >> 1; 499 } 500 } 501 if (width & 1) { // last pixel 502 const uint32_t v0 = src[2 * i + 0]; 503 const int r = (v0 >> 14) & 0x3fc; 504 const int g = (v0 >> 6) & 0x3fc; 505 const int b = (v0 << 2) & 0x3fc; 506 if (!(y_pos & 1)) { // even lines 507 u[i] = VP8RGBToU(r, g, b); 508 v[i] = VP8RGBToV(r, g, b); 509 } else { // odd lines (note: we could just skip this) 510 const int tmp_u = VP8RGBToU(r, g, b); 511 const int tmp_v = VP8RGBToV(r, g, b); 512 u[i] = (u[i] + tmp_u + 1) >> 1; 513 v[i] = (v[i] + tmp_v + 1) >> 1; 514 } 515 } 516 } 517 // Lastly, store alpha if needed. 518 if (buf->a != NULL) { 519 int i; 520 uint8_t* const a = buf->a + y_pos * buf->a_stride; 521 for (i = 0; i < width; ++i) a[i] = (src[i] >> 24); 522 } 523} 524 525static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) { 526 WebPRescaler* const rescaler = dec->rescaler; 527 const uint32_t* const src = (const uint32_t*)rescaler->dst; 528 const int dst_width = rescaler->dst_width; 529 int num_lines_out = 0; 530 while (WebPRescalerHasPendingOutput(rescaler)) { 531 WebPRescalerExportRow(rescaler); 532 ConvertToYUVA(src, dst_width, y_pos, dec->output_); 533 ++y_pos; 534 ++num_lines_out; 535 } 536 return num_lines_out; 537} 538 539static int EmitRescaledRowsYUVA(const VP8LDecoder* const dec, 540 const uint32_t* const data, 541 int in_stride, int mb_h) { 542 const uint8_t* const in = (const uint8_t*)data; 543 int num_lines_in = 0; 544 int y_pos = dec->last_out_row_; 545 while (num_lines_in < mb_h) { 546 const uint8_t* const row_in = in + num_lines_in * in_stride; 547 num_lines_in += WebPRescalerImport(dec->rescaler, mb_h - num_lines_in, 548 row_in, in_stride); 549 y_pos += ExportYUVA(dec, y_pos); 550 } 551 return y_pos; 552} 553 554static int EmitRowsYUVA(const VP8LDecoder* const dec, 555 const uint32_t* const data, int in_stride, 556 int mb_w, int num_rows) { 557 int y_pos = dec->last_out_row_; 558 const uint8_t* row_in = (const uint8_t*)data; 559 while (num_rows-- > 0) { 560 ConvertToYUVA((const uint32_t*)row_in, mb_w, y_pos, dec->output_); 561 row_in += in_stride; 562 ++y_pos; 563 } 564 return y_pos; 565} 566 567//------------------------------------------------------------------------------ 568// Cropping. 569 570// Sets io->mb_y, io->mb_h & io->mb_w according to start row, end row and 571// crop options. Also updates the input data pointer, so that it points to the 572// start of the cropped window. 573// Note that 'pixel_stride' is in units of 'uint32_t' (and not 'bytes). 574// Returns true if the crop window is not empty. 575static int SetCropWindow(VP8Io* const io, int y_start, int y_end, 576 const uint32_t** const in_data, int pixel_stride) { 577 assert(y_start < y_end); 578 assert(io->crop_left < io->crop_right); 579 if (y_end > io->crop_bottom) { 580 y_end = io->crop_bottom; // make sure we don't overflow on last row. 581 } 582 if (y_start < io->crop_top) { 583 const int delta = io->crop_top - y_start; 584 y_start = io->crop_top; 585 *in_data += pixel_stride * delta; 586 } 587 if (y_start >= y_end) return 0; // Crop window is empty. 588 589 *in_data += io->crop_left; 590 591 io->mb_y = y_start - io->crop_top; 592 io->mb_w = io->crop_right - io->crop_left; 593 io->mb_h = y_end - y_start; 594 return 1; // Non-empty crop window. 595} 596 597//------------------------------------------------------------------------------ 598 599static WEBP_INLINE int GetMetaIndex( 600 const uint32_t* const image, int xsize, int bits, int x, int y) { 601 if (bits == 0) return 0; 602 return image[xsize * (y >> bits) + (x >> bits)]; 603} 604 605static WEBP_INLINE HTreeGroup* GetHtreeGroupForPos(VP8LMetadata* const hdr, 606 int x, int y) { 607 const int meta_index = GetMetaIndex(hdr->huffman_image_, hdr->huffman_xsize_, 608 hdr->huffman_subsample_bits_, x, y); 609 assert(meta_index < hdr->num_htree_groups_); 610 return hdr->htree_groups_ + meta_index; 611} 612 613//------------------------------------------------------------------------------ 614// Main loop, with custom row-processing function 615 616typedef void (*ProcessRowsFunc)(VP8LDecoder* const dec, int row); 617 618static void ApplyInverseTransforms(VP8LDecoder* const dec, int num_rows, 619 const uint32_t* const rows) { 620 int n = dec->next_transform_; 621 const int cache_pixs = dec->width_ * num_rows; 622 const int start_row = dec->last_row_; 623 const int end_row = start_row + num_rows; 624 const uint32_t* rows_in = rows; 625 uint32_t* const rows_out = dec->argb_cache_; 626 627 // Inverse transforms. 628 // TODO: most transforms only need to operate on the cropped region only. 629 memcpy(rows_out, rows_in, cache_pixs * sizeof(*rows_out)); 630 while (n-- > 0) { 631 VP8LTransform* const transform = &dec->transforms_[n]; 632 VP8LInverseTransform(transform, start_row, end_row, rows_in, rows_out); 633 rows_in = rows_out; 634 } 635} 636 637// Processes (transforms, scales & color-converts) the rows decoded after the 638// last call. 639static void ProcessRows(VP8LDecoder* const dec, int row) { 640 const uint32_t* const rows = dec->argb_ + dec->width_ * dec->last_row_; 641 const int num_rows = row - dec->last_row_; 642 643 if (num_rows <= 0) return; // Nothing to be done. 644 ApplyInverseTransforms(dec, num_rows, rows); 645 646 // Emit output. 647 { 648 VP8Io* const io = dec->io_; 649 const uint32_t* rows_data = dec->argb_cache_; 650 if (!SetCropWindow(io, dec->last_row_, row, &rows_data, io->width)) { 651 // Nothing to output (this time). 652 } else { 653 const WebPDecBuffer* const output = dec->output_; 654 const int in_stride = io->width * sizeof(*rows_data); 655 if (output->colorspace < MODE_YUV) { // convert to RGBA 656 const WebPRGBABuffer* const buf = &output->u.RGBA; 657 uint8_t* const rgba = buf->rgba + dec->last_out_row_ * buf->stride; 658 const int num_rows_out = io->use_scaling ? 659 EmitRescaledRows(dec, rows_data, in_stride, io->mb_h, 660 rgba, buf->stride) : 661 EmitRows(output->colorspace, rows_data, in_stride, 662 io->mb_w, io->mb_h, rgba, buf->stride); 663 // Update 'last_out_row_'. 664 dec->last_out_row_ += num_rows_out; 665 } else { // convert to YUVA 666 dec->last_out_row_ = io->use_scaling ? 667 EmitRescaledRowsYUVA(dec, rows_data, in_stride, io->mb_h) : 668 EmitRowsYUVA(dec, rows_data, in_stride, io->mb_w, io->mb_h); 669 } 670 assert(dec->last_out_row_ <= output->height); 671 } 672 } 673 674 // Update 'last_row_'. 675 dec->last_row_ = row; 676 assert(dec->last_row_ <= dec->height_); 677} 678 679static int DecodeImageData(VP8LDecoder* const dec, 680 uint32_t* const data, int width, int height, 681 ProcessRowsFunc process_func) { 682 int ok = 1; 683 int col = 0, row = 0; 684 VP8LBitReader* const br = &dec->br_; 685 VP8LMetadata* const hdr = &dec->hdr_; 686 HTreeGroup* htree_group = hdr->htree_groups_; 687 uint32_t* src = data; 688 uint32_t* last_cached = data; 689 uint32_t* const src_end = data + width * height; 690 const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES; 691 const int color_cache_limit = len_code_limit + hdr->color_cache_size_; 692 VP8LColorCache* const color_cache = 693 (hdr->color_cache_size_ > 0) ? &hdr->color_cache_ : NULL; 694 const int mask = hdr->huffman_mask_; 695 696 assert(htree_group != NULL); 697 698 while (!br->eos_ && src < src_end) { 699 int code; 700 // Only update when changing tile. Note we could use the following test: 701 // if "((((prev_col ^ col) | prev_row ^ row)) > mask)" -> tile changed 702 // but that's actually slower and requires storing the previous col/row 703 if ((col & mask) == 0) { 704 htree_group = GetHtreeGroupForPos(hdr, col, row); 705 } 706 VP8LFillBitWindow(br); 707 code = ReadSymbol(&htree_group->htrees_[GREEN], br); 708 if (code < NUM_LITERAL_CODES) { // Literal. 709 int red, green, blue, alpha; 710 red = ReadSymbol(&htree_group->htrees_[RED], br); 711 green = code; 712 VP8LFillBitWindow(br); 713 blue = ReadSymbol(&htree_group->htrees_[BLUE], br); 714 alpha = ReadSymbol(&htree_group->htrees_[ALPHA], br); 715 *src = (alpha << 24) + (red << 16) + (green << 8) + blue; 716 AdvanceByOne: 717 ++src; 718 ++col; 719 if (col >= width) { 720 col = 0; 721 ++row; 722 if ((process_func != NULL) && (row % NUM_ARGB_CACHE_ROWS == 0)) { 723 process_func(dec, row); 724 } 725 if (color_cache != NULL) { 726 while (last_cached < src) { 727 VP8LColorCacheInsert(color_cache, *last_cached++); 728 } 729 } 730 } 731 } else if (code < len_code_limit) { // Backward reference 732 int dist_code, dist; 733 const int length_sym = code - NUM_LITERAL_CODES; 734 const int length = GetCopyLength(length_sym, br); 735 const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br); 736 VP8LFillBitWindow(br); 737 dist_code = GetCopyDistance(dist_symbol, br); 738 dist = PlaneCodeToDistance(width, dist_code); 739 if (src - data < dist || src_end - src < length) { 740 ok = 0; 741 goto End; 742 } 743 { 744 int i; 745 for (i = 0; i < length; ++i) src[i] = src[i - dist]; 746 src += length; 747 } 748 col += length; 749 while (col >= width) { 750 col -= width; 751 ++row; 752 if ((process_func != NULL) && (row % NUM_ARGB_CACHE_ROWS == 0)) { 753 process_func(dec, row); 754 } 755 } 756 if (src < src_end) { 757 htree_group = GetHtreeGroupForPos(hdr, col, row); 758 if (color_cache != NULL) { 759 while (last_cached < src) { 760 VP8LColorCacheInsert(color_cache, *last_cached++); 761 } 762 } 763 } 764 } else if (code < color_cache_limit) { // Color cache. 765 const int key = code - len_code_limit; 766 assert(color_cache != NULL); 767 while (last_cached < src) { 768 VP8LColorCacheInsert(color_cache, *last_cached++); 769 } 770 *src = VP8LColorCacheLookup(color_cache, key); 771 goto AdvanceByOne; 772 } else { // Not reached. 773 ok = 0; 774 goto End; 775 } 776 ok = !br->error_; 777 if (!ok) goto End; 778 } 779 // Process the remaining rows corresponding to last row-block. 780 if (process_func != NULL) process_func(dec, row); 781 782 End: 783 if (br->error_ || !ok || (br->eos_ && src < src_end)) { 784 ok = 0; 785 dec->status_ = (!br->eos_) ? 786 VP8_STATUS_BITSTREAM_ERROR : VP8_STATUS_SUSPENDED; 787 } else if (src == src_end) { 788 dec->state_ = READ_DATA; 789 } 790 791 return ok; 792} 793 794// ----------------------------------------------------------------------------- 795// VP8LTransform 796 797static void ClearTransform(VP8LTransform* const transform) { 798 free(transform->data_); 799 transform->data_ = NULL; 800} 801 802// For security reason, we need to remap the color map to span 803// the total possible bundled values, and not just the num_colors. 804static int ExpandColorMap(int num_colors, VP8LTransform* const transform) { 805 int i; 806 const int final_num_colors = 1 << (8 >> transform->bits_); 807 uint32_t* const new_color_map = 808 (uint32_t*)WebPSafeMalloc((uint64_t)final_num_colors, 809 sizeof(*new_color_map)); 810 if (new_color_map == NULL) { 811 return 0; 812 } else { 813 uint8_t* const data = (uint8_t*)transform->data_; 814 uint8_t* const new_data = (uint8_t*)new_color_map; 815 new_color_map[0] = transform->data_[0]; 816 for (i = 4; i < 4 * num_colors; ++i) { 817 // Equivalent to AddPixelEq(), on a byte-basis. 818 new_data[i] = (data[i] + new_data[i - 4]) & 0xff; 819 } 820 for (; i < 4 * final_num_colors; ++i) 821 new_data[i] = 0; // black tail. 822 free(transform->data_); 823 transform->data_ = new_color_map; 824 } 825 return 1; 826} 827 828static int ReadTransform(int* const xsize, int const* ysize, 829 VP8LDecoder* const dec) { 830 int ok = 1; 831 VP8LBitReader* const br = &dec->br_; 832 VP8LTransform* transform = &dec->transforms_[dec->next_transform_]; 833 const VP8LImageTransformType type = 834 (VP8LImageTransformType)VP8LReadBits(br, 2); 835 836 // Each transform type can only be present once in the stream. 837 if (dec->transforms_seen_ & (1U << type)) { 838 return 0; // Already there, let's not accept the second same transform. 839 } 840 dec->transforms_seen_ |= (1U << type); 841 842 transform->type_ = type; 843 transform->xsize_ = *xsize; 844 transform->ysize_ = *ysize; 845 transform->data_ = NULL; 846 ++dec->next_transform_; 847 assert(dec->next_transform_ <= NUM_TRANSFORMS); 848 849 switch (type) { 850 case PREDICTOR_TRANSFORM: 851 case CROSS_COLOR_TRANSFORM: 852 transform->bits_ = VP8LReadBits(br, 3) + 2; 853 ok = DecodeImageStream(VP8LSubSampleSize(transform->xsize_, 854 transform->bits_), 855 VP8LSubSampleSize(transform->ysize_, 856 transform->bits_), 857 0, dec, &transform->data_); 858 break; 859 case COLOR_INDEXING_TRANSFORM: { 860 const int num_colors = VP8LReadBits(br, 8) + 1; 861 const int bits = (num_colors > 16) ? 0 862 : (num_colors > 4) ? 1 863 : (num_colors > 2) ? 2 864 : 3; 865 *xsize = VP8LSubSampleSize(transform->xsize_, bits); 866 transform->bits_ = bits; 867 ok = DecodeImageStream(num_colors, 1, 0, dec, &transform->data_); 868 ok = ok && ExpandColorMap(num_colors, transform); 869 break; 870 } 871 case SUBTRACT_GREEN: 872 break; 873 default: 874 assert(0); // can't happen 875 break; 876 } 877 878 return ok; 879} 880 881// ----------------------------------------------------------------------------- 882// VP8LMetadata 883 884static void InitMetadata(VP8LMetadata* const hdr) { 885 assert(hdr); 886 memset(hdr, 0, sizeof(*hdr)); 887} 888 889static void ClearMetadata(VP8LMetadata* const hdr) { 890 assert(hdr); 891 892 free(hdr->huffman_image_); 893 DeleteHtreeGroups(hdr->htree_groups_, hdr->num_htree_groups_); 894 VP8LColorCacheClear(&hdr->color_cache_); 895 InitMetadata(hdr); 896} 897 898// ----------------------------------------------------------------------------- 899// VP8LDecoder 900 901VP8LDecoder* VP8LNew(void) { 902 VP8LDecoder* const dec = (VP8LDecoder*)calloc(1, sizeof(*dec)); 903 if (dec == NULL) return NULL; 904 dec->status_ = VP8_STATUS_OK; 905 dec->action_ = READ_DIM; 906 dec->state_ = READ_DIM; 907 return dec; 908} 909 910void VP8LClear(VP8LDecoder* const dec) { 911 int i; 912 if (dec == NULL) return; 913 ClearMetadata(&dec->hdr_); 914 915 free(dec->argb_); 916 dec->argb_ = NULL; 917 for (i = 0; i < dec->next_transform_; ++i) { 918 ClearTransform(&dec->transforms_[i]); 919 } 920 dec->next_transform_ = 0; 921 dec->transforms_seen_ = 0; 922 923 free(dec->rescaler_memory); 924 dec->rescaler_memory = NULL; 925 926 dec->output_ = NULL; // leave no trace behind 927} 928 929void VP8LDelete(VP8LDecoder* const dec) { 930 if (dec != NULL) { 931 VP8LClear(dec); 932 free(dec); 933 } 934} 935 936static void UpdateDecoder(VP8LDecoder* const dec, int width, int height) { 937 VP8LMetadata* const hdr = &dec->hdr_; 938 const int num_bits = hdr->huffman_subsample_bits_; 939 dec->width_ = width; 940 dec->height_ = height; 941 942 hdr->huffman_xsize_ = VP8LSubSampleSize(width, num_bits); 943 hdr->huffman_mask_ = (num_bits == 0) ? ~0 : (1 << num_bits) - 1; 944} 945 946static int DecodeImageStream(int xsize, int ysize, 947 int is_level0, 948 VP8LDecoder* const dec, 949 uint32_t** const decoded_data) { 950 int ok = 1; 951 int transform_xsize = xsize; 952 int transform_ysize = ysize; 953 VP8LBitReader* const br = &dec->br_; 954 VP8LMetadata* const hdr = &dec->hdr_; 955 uint32_t* data = NULL; 956 int color_cache_bits = 0; 957 958 // Read the transforms (may recurse). 959 if (is_level0) { 960 while (ok && VP8LReadBits(br, 1)) { 961 ok = ReadTransform(&transform_xsize, &transform_ysize, dec); 962 } 963 } 964 965 // Color cache 966 if (ok && VP8LReadBits(br, 1)) { 967 color_cache_bits = VP8LReadBits(br, 4); 968 ok = (color_cache_bits >= 1 && color_cache_bits <= MAX_CACHE_BITS); 969 if (!ok) { 970 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 971 goto End; 972 } 973 } 974 975 // Read the Huffman codes (may recurse). 976 ok = ok && ReadHuffmanCodes(dec, transform_xsize, transform_ysize, 977 color_cache_bits, is_level0); 978 if (!ok) { 979 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 980 goto End; 981 } 982 983 // Finish setting up the color-cache 984 if (color_cache_bits > 0) { 985 hdr->color_cache_size_ = 1 << color_cache_bits; 986 if (!VP8LColorCacheInit(&hdr->color_cache_, color_cache_bits)) { 987 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 988 ok = 0; 989 goto End; 990 } 991 } else { 992 hdr->color_cache_size_ = 0; 993 } 994 UpdateDecoder(dec, transform_xsize, transform_ysize); 995 996 if (is_level0) { // level 0 complete 997 dec->state_ = READ_HDR; 998 goto End; 999 } 1000 1001 { 1002 const uint64_t total_size = (uint64_t)transform_xsize * transform_ysize; 1003 data = (uint32_t*)WebPSafeMalloc(total_size, sizeof(*data)); 1004 if (data == NULL) { 1005 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 1006 ok = 0; 1007 goto End; 1008 } 1009 } 1010 1011 // Use the Huffman trees to decode the LZ77 encoded data. 1012 ok = DecodeImageData(dec, data, transform_xsize, transform_ysize, NULL); 1013 ok = ok && !br->error_; 1014 1015 End: 1016 1017 if (!ok) { 1018 free(data); 1019 ClearMetadata(hdr); 1020 // If not enough data (br.eos_) resulted in BIT_STREAM_ERROR, update the 1021 // status appropriately. 1022 if (dec->status_ == VP8_STATUS_BITSTREAM_ERROR && dec->br_.eos_) { 1023 dec->status_ = VP8_STATUS_SUSPENDED; 1024 } 1025 } else { 1026 if (decoded_data != NULL) { 1027 *decoded_data = data; 1028 } else { 1029 // We allocate image data in this function only for transforms. At level 0 1030 // (that is: not the transforms), we shouldn't have allocated anything. 1031 assert(data == NULL); 1032 assert(is_level0); 1033 } 1034 if (!is_level0) ClearMetadata(hdr); // Clean up temporary data behind. 1035 } 1036 return ok; 1037} 1038 1039//------------------------------------------------------------------------------ 1040// Allocate dec->argb_ and dec->argb_cache_ using dec->width_ and dec->height_ 1041 1042static int AllocateARGBBuffers(VP8LDecoder* const dec, int final_width) { 1043 const uint64_t num_pixels = (uint64_t)dec->width_ * dec->height_; 1044 // Scratch buffer corresponding to top-prediction row for transforming the 1045 // first row in the row-blocks. 1046 const uint64_t cache_top_pixels = final_width; 1047 // Scratch buffer for temporary BGRA storage. 1048 const uint64_t cache_pixels = (uint64_t)final_width * NUM_ARGB_CACHE_ROWS; 1049 const uint64_t total_num_pixels = 1050 num_pixels + cache_top_pixels + cache_pixels; 1051 1052 assert(dec->width_ <= final_width); 1053 dec->argb_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(*dec->argb_)); 1054 if (dec->argb_ == NULL) { 1055 dec->argb_cache_ = NULL; // for sanity check 1056 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 1057 return 0; 1058 } 1059 dec->argb_cache_ = dec->argb_ + num_pixels + cache_top_pixels; 1060 return 1; 1061} 1062 1063//------------------------------------------------------------------------------ 1064// Special row-processing that only stores the alpha data. 1065 1066static void ExtractAlphaRows(VP8LDecoder* const dec, int row) { 1067 const int num_rows = row - dec->last_row_; 1068 const uint32_t* const in = dec->argb_ + dec->width_ * dec->last_row_; 1069 1070 if (num_rows <= 0) return; // Nothing to be done. 1071 ApplyInverseTransforms(dec, num_rows, in); 1072 1073 // Extract alpha (which is stored in the green plane). 1074 { 1075 const int width = dec->io_->width; // the final width (!= dec->width_) 1076 const int cache_pixs = width * num_rows; 1077 uint8_t* const dst = (uint8_t*)dec->io_->opaque + width * dec->last_row_; 1078 const uint32_t* const src = dec->argb_cache_; 1079 int i; 1080 for (i = 0; i < cache_pixs; ++i) dst[i] = (src[i] >> 8) & 0xff; 1081 } 1082 1083 dec->last_row_ = dec->last_out_row_ = row; 1084} 1085 1086int VP8LDecodeAlphaImageStream(int width, int height, const uint8_t* const data, 1087 size_t data_size, uint8_t* const output) { 1088 VP8Io io; 1089 int ok = 0; 1090 VP8LDecoder* const dec = VP8LNew(); 1091 if (dec == NULL) return 0; 1092 1093 dec->width_ = width; 1094 dec->height_ = height; 1095 dec->io_ = &io; 1096 1097 VP8InitIo(&io); 1098 WebPInitCustomIo(NULL, &io); // Just a sanity Init. io won't be used. 1099 io.opaque = output; 1100 io.width = width; 1101 io.height = height; 1102 1103 dec->status_ = VP8_STATUS_OK; 1104 VP8LInitBitReader(&dec->br_, data, data_size); 1105 1106 dec->action_ = READ_HDR; 1107 if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Err; 1108 1109 // Allocate output (note that dec->width_ may have changed here). 1110 if (!AllocateARGBBuffers(dec, width)) goto Err; 1111 1112 // Decode (with special row processing). 1113 dec->action_ = READ_DATA; 1114 ok = DecodeImageData(dec, dec->argb_, dec->width_, dec->height_, 1115 ExtractAlphaRows); 1116 1117 Err: 1118 VP8LDelete(dec); 1119 return ok; 1120} 1121 1122//------------------------------------------------------------------------------ 1123 1124int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io) { 1125 int width, height, has_alpha; 1126 1127 if (dec == NULL) return 0; 1128 if (io == NULL) { 1129 dec->status_ = VP8_STATUS_INVALID_PARAM; 1130 return 0; 1131 } 1132 1133 dec->io_ = io; 1134 dec->status_ = VP8_STATUS_OK; 1135 VP8LInitBitReader(&dec->br_, io->data, io->data_size); 1136 if (!ReadImageInfo(&dec->br_, &width, &height, &has_alpha)) { 1137 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 1138 goto Error; 1139 } 1140 dec->state_ = READ_DIM; 1141 io->width = width; 1142 io->height = height; 1143 1144 dec->action_ = READ_HDR; 1145 if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Error; 1146 return 1; 1147 1148 Error: 1149 VP8LClear(dec); 1150 assert(dec->status_ != VP8_STATUS_OK); 1151 return 0; 1152} 1153 1154int VP8LDecodeImage(VP8LDecoder* const dec) { 1155 VP8Io* io = NULL; 1156 WebPDecParams* params = NULL; 1157 1158 // Sanity checks. 1159 if (dec == NULL) return 0; 1160 1161 io = dec->io_; 1162 assert(io != NULL); 1163 params = (WebPDecParams*)io->opaque; 1164 assert(params != NULL); 1165 dec->output_ = params->output; 1166 assert(dec->output_ != NULL); 1167 1168 // Initialization. 1169 if (!WebPIoInitFromOptions(params->options, io, MODE_BGRA)) { 1170 dec->status_ = VP8_STATUS_INVALID_PARAM; 1171 goto Err; 1172 } 1173 1174 if (!AllocateARGBBuffers(dec, io->width)) goto Err; 1175 1176 if (io->use_scaling && !AllocateAndInitRescaler(dec, io)) goto Err; 1177 1178 // Decode. 1179 dec->action_ = READ_DATA; 1180 if (!DecodeImageData(dec, dec->argb_, dec->width_, dec->height_, 1181 ProcessRows)) { 1182 goto Err; 1183 } 1184 1185 // Cleanup. 1186 params->last_y = dec->last_out_row_; 1187 VP8LClear(dec); 1188 return 1; 1189 1190 Err: 1191 VP8LClear(dec); 1192 assert(dec->status_ != VP8_STATUS_OK); 1193 return 0; 1194} 1195 1196//------------------------------------------------------------------------------ 1197 1198#if defined(__cplusplus) || defined(c_plusplus) 1199} // extern "C" 1200#endif 1201