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1 <?php 2 /** 3 * Copyright (c) 2021, Alliance for Open Media. All rights reserved 4 * 5 * This source code is subject to the terms of the BSD 2 Clause License and 6 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License 7 * was not distributed with this source code in the LICENSE file, you can 8 * obtain it at www.aomedia.org/license/software. If the Alliance for Open 9 * Media Patent License 1.0 was not distributed with this source code in the 10 * PATENTS file, you can obtain it at www.aomedia.org/license/patent. 11 * 12 * Note: this class is from libavifinfo - https://aomedia.googlesource.com/libavifinfo/+/refs/heads/main/avifinfo.php at f509487. 13 * It is used as a fallback to parse AVIF files when the server doesn't support AVIF, 14 * primarily to identify the width and height of the image. 15 * 16 * Note PHP 8.2 added native support for AVIF, so this class can be removed when WordPress requires PHP 8.2. 17 */ 18 19 namespace Avifinfo; 20 21 const FOUND = 0; // Input correctly parsed and information retrieved. 22 const NOT_FOUND = 1; // Input correctly parsed but information is missing or elsewhere. 23 const TRUNCATED = 2; // Input correctly parsed until missing bytes to continue. 24 const ABORTED = 3; // Input correctly parsed until stopped to avoid timeout or crash. 25 const INVALID = 4; // Input incorrectly parsed. 26 27 const MAX_SIZE = 4294967295; // Unlikely to be insufficient to parse AVIF headers. 28 const MAX_NUM_BOXES = 4096; // Be reasonable. Avoid timeouts and out-of-memory. 29 const MAX_VALUE = 255; 30 const MAX_TILES = 16; 31 const MAX_PROPS = 32; 32 const MAX_FEATURES = 8; 33 const UNDEFINED = 0; // Value was not yet parsed. 34 35 /** 36 * Reads an unsigned integer with most significant bits first. 37 * 38 * @param binary string $input Must be at least $num_bytes-long. 39 * @param int $num_bytes Number of parsed bytes. 40 * @return int Value. 41 */ 42 function read_big_endian( $input, $num_bytes ) { 43 if ( $num_bytes == 1 ) { 44 return unpack( 'C', $input ) [1]; 45 } else if ( $num_bytes == 2 ) { 46 return unpack( 'n', $input ) [1]; 47 } else if ( $num_bytes == 3 ) { 48 $bytes = unpack( 'C3', $input ); 49 return ( $bytes[1] << 16 ) | ( $bytes[2] << 8 ) | $bytes[3]; 50 } else { // $num_bytes is 4 51 // This might fail to read unsigned values >= 2^31 on 32-bit systems. 52 // See https://www.php.net/manual/en/function.unpack.php#106041 53 return unpack( 'N', $input ) [1]; 54 } 55 } 56 57 /** 58 * Reads bytes and advances the stream position by the same count. 59 * 60 * @param stream $handle Bytes will be read from this resource. 61 * @param int $num_bytes Number of bytes read. Must be greater than 0. 62 * @return binary string|false The raw bytes or false on failure. 63 */ 64 function read( $handle, $num_bytes ) { 65 $data = fread( $handle, $num_bytes ); 66 return ( $data !== false && strlen( $data ) >= $num_bytes ) ? $data : false; 67 } 68 69 /** 70 * Advances the stream position by the given offset. 71 * 72 * @param stream $handle Bytes will be skipped from this resource. 73 * @param int $num_bytes Number of skipped bytes. Can be 0. 74 * @return bool True on success or false on failure. 75 */ 76 // Skips 'num_bytes' from the 'stream'. 'num_bytes' can be zero. 77 function skip( $handle, $num_bytes ) { 78 return ( fseek( $handle, $num_bytes, SEEK_CUR ) == 0 ); 79 } 80 81 //------------------------------------------------------------------------------ 82 // Features are parsed into temporary property associations. 83 84 class Tile { // Tile item id <-> parent item id associations. 85 public $tile_item_id; 86 public $parent_item_id; 87 } 88 89 class Prop { // Property index <-> item id associations. 90 public $property_index; 91 public $item_id; 92 } 93 94 class Dim_Prop { // Property <-> features associations. 95 public $property_index; 96 public $width; 97 public $height; 98 } 99 100 class Chan_Prop { // Property <-> features associations. 101 public $property_index; 102 public $bit_depth; 103 public $num_channels; 104 } 105 106 class Features { 107 public $has_primary_item = false; // True if "pitm" was parsed. 108 public $has_alpha = false; // True if an alpha "auxC" was parsed. 109 public $primary_item_id; 110 public $primary_item_features = array( // Deduced from the data below. 111 'width' => UNDEFINED, // In number of pixels. 112 'height' => UNDEFINED, // Ignores mirror and rotation. 113 'bit_depth' => UNDEFINED, // Likely 8, 10 or 12 bits per channel per pixel. 114 'num_channels' => UNDEFINED // Likely 1, 2, 3 or 4 channels: 115 // (1 monochrome or 3 colors) + (0 or 1 alpha) 116 ); 117 118 public $tiles = array(); // Tile[] 119 public $props = array(); // Prop[] 120 public $dim_props = array(); // Dim_Prop[] 121 public $chan_props = array(); // Chan_Prop[] 122 123 /** 124 * Binds the width, height, bit depth and number of channels from stored internal features. 125 * 126 * @param int $target_item_id Id of the item whose features will be bound. 127 * @param int $tile_depth Maximum recursion to search within tile-parent relations. 128 * @return Status FOUND on success or NOT_FOUND on failure. 129 */ 130 private function get_item_features( $target_item_id, $tile_depth ) { 131 foreach ( $this->props as $prop ) { 132 if ( $prop->item_id != $target_item_id ) { 133 continue; 134 } 135 136 // Retrieve the width and height of the primary item if not already done. 137 if ( $target_item_id == $this->primary_item_id && 138 ( $this->primary_item_features['width'] == UNDEFINED || 139 $this->primary_item_features['height'] == UNDEFINED ) ) { 140 foreach ( $this->dim_props as $dim_prop ) { 141 if ( $dim_prop->property_index != $prop->property_index ) { 142 continue; 143 } 144 $this->primary_item_features['width'] = $dim_prop->width; 145 $this->primary_item_features['height'] = $dim_prop->height; 146 if ( $this->primary_item_features['bit_depth'] != UNDEFINED && 147 $this->primary_item_features['num_channels'] != UNDEFINED ) { 148 return FOUND; 149 } 150 break; 151 } 152 } 153 // Retrieve the bit depth and number of channels of the target item if not 154 // already done. 155 if ( $this->primary_item_features['bit_depth'] == UNDEFINED || 156 $this->primary_item_features['num_channels'] == UNDEFINED ) { 157 foreach ( $this->chan_props as $chan_prop ) { 158 if ( $chan_prop->property_index != $prop->property_index ) { 159 continue; 160 } 161 $this->primary_item_features['bit_depth'] = $chan_prop->bit_depth; 162 $this->primary_item_features['num_channels'] = $chan_prop->num_channels; 163 if ( $this->primary_item_features['width'] != UNDEFINED && 164 $this->primary_item_features['height'] != UNDEFINED ) { 165 return FOUND; 166 } 167 break; 168 } 169 } 170 } 171 172 // Check for the bit_depth and num_channels in a tile if not yet found. 173 if ( $tile_depth < 3 ) { 174 foreach ( $this->tiles as $tile ) { 175 if ( $tile->parent_item_id != $target_item_id ) { 176 continue; 177 } 178 $status = $this->get_item_features( $tile->tile_item_id, $tile_depth + 1 ); 179 if ( $status != NOT_FOUND ) { 180 return $status; 181 } 182 } 183 } 184 return NOT_FOUND; 185 } 186 187 /** 188 * Finds the width, height, bit depth and number of channels of the primary item. 189 * 190 * @return Status FOUND on success or NOT_FOUND on failure. 191 */ 192 public function get_primary_item_features() { 193 // Nothing to do without the primary item ID. 194 if ( !$this->has_primary_item ) { 195 return NOT_FOUND; 196 } 197 // Early exit. 198 if ( empty( $this->dim_props ) || empty( $this->chan_props ) ) { 199 return NOT_FOUND; 200 } 201 $status = $this->get_item_features( $this->primary_item_id, /*tile_depth=*/ 0 ); 202 if ( $status != FOUND ) { 203 return $status; 204 } 205 206 // "auxC" is parsed before the "ipma" properties so it is known now, if any. 207 if ( $this->has_alpha ) { 208 ++$this->primary_item_features['num_channels']; 209 } 210 return FOUND; 211 } 212 } 213 214 //------------------------------------------------------------------------------ 215 216 class Box { 217 public $size; // In bytes. 218 public $type; // Four characters. 219 public $version; // 0 or actual version if this is a full box. 220 public $flags; // 0 or actual value if this is a full box. 221 public $content_size; // 'size' minus the header size. 222 223 /** 224 * Reads the box header. 225 * 226 * @param stream $handle The resource the header will be parsed from. 227 * @param int $num_parsed_boxes The total number of parsed boxes. Prevents timeouts. 228 * @param int $num_remaining_bytes The number of bytes that should be available from the resource. 229 * @return Status FOUND on success or an error on failure. 230 */ 231 public function parse( $handle, &$num_parsed_boxes, $num_remaining_bytes = MAX_SIZE ) { 232 // See ISO/IEC 14496-12:2012(E) 4.2 233 $header_size = 8; // box 32b size + 32b type (at least) 234 if ( $header_size > $num_remaining_bytes ) { 235 return INVALID; 236 } 237 if ( !( $data = read( $handle, 8 ) ) ) { 238 return TRUNCATED; 239 } 240 $this->size = read_big_endian( $data, 4 ); 241 $this->type = substr( $data, 4, 4 ); 242 // 'box->size==1' means 64-bit size should be read after the box type. 243 // 'box->size==0' means this box extends to all remaining bytes. 244 if ( $this->size == 1 ) { 245 $header_size += 8; 246 if ( $header_size > $num_remaining_bytes ) { 247 return INVALID; 248 } 249 if ( !( $data = read( $handle, 8 ) ) ) { 250 return TRUNCATED; 251 } 252 // Stop the parsing if any box has a size greater than 4GB. 253 if ( read_big_endian( $data, 4 ) != 0 ) { 254 return ABORTED; 255 } 256 // Read the 32 least-significant bits. 257 $this->size = read_big_endian( substr( $data, 4, 4 ), 4 ); 258 } else if ( $this->size == 0 ) { 259 $this->size = $num_remaining_bytes; 260 } 261 if ( $this->size < $header_size ) { 262 return INVALID; 263 } 264 if ( $this->size > $num_remaining_bytes ) { 265 return INVALID; 266 } 267 268 $has_fullbox_header = $this->type == 'meta' || $this->type == 'pitm' || 269 $this->type == 'ipma' || $this->type == 'ispe' || 270 $this->type == 'pixi' || $this->type == 'iref' || 271 $this->type == 'auxC'; 272 if ( $has_fullbox_header ) { 273 $header_size += 4; 274 } 275 if ( $this->size < $header_size ) { 276 return INVALID; 277 } 278 $this->content_size = $this->size - $header_size; 279 // Avoid timeouts. The maximum number of parsed boxes is arbitrary. 280 ++$num_parsed_boxes; 281 if ( $num_parsed_boxes >= MAX_NUM_BOXES ) { 282 return ABORTED; 283 } 284 285 $this->version = 0; 286 $this->flags = 0; 287 if ( $has_fullbox_header ) { 288 if ( !( $data = read( $handle, 4 ) ) ) { 289 return TRUNCATED; 290 } 291 $this->version = read_big_endian( $data, 1 ); 292 $this->flags = read_big_endian( substr( $data, 1, 3 ), 3 ); 293 // See AV1 Image File Format (AVIF) 8.1 294 // at https://aomediacodec.github.io/av1-avif/#avif-boxes (available when 295 // https://github.com/AOMediaCodec/av1-avif/pull/170 is merged). 296 $is_parsable = ( $this->type == 'meta' && $this->version <= 0 ) || 297 ( $this->type == 'pitm' && $this->version <= 1 ) || 298 ( $this->type == 'ipma' && $this->version <= 1 ) || 299 ( $this->type == 'ispe' && $this->version <= 0 ) || 300 ( $this->type == 'pixi' && $this->version <= 0 ) || 301 ( $this->type == 'iref' && $this->version <= 1 ) || 302 ( $this->type == 'auxC' && $this->version <= 0 ); 303 // Instead of considering this file as invalid, skip unparsable boxes. 304 if ( !$is_parsable ) { 305 $this->type = 'unknownversion'; 306 } 307 } 308 // print_r( $this ); // Uncomment to print all boxes. 309 return FOUND; 310 } 311 } 312 313 //------------------------------------------------------------------------------ 314 315 class Parser { 316 private $handle; // Input stream. 317 private $num_parsed_boxes = 0; 318 private $data_was_skipped = false; 319 public $features; 320 321 function __construct( $handle ) { 322 $this->handle = $handle; 323 $this->features = new Features(); 324 } 325 326 /** 327 * Parses an "ipco" box. 328 * 329 * "ispe" is used for width and height, "pixi" and "av1C" are used for bit depth 330 * and number of channels, and "auxC" is used for alpha. 331 * 332 * @param stream $handle The resource the box will be parsed from. 333 * @param int $num_remaining_bytes The number of bytes that should be available from the resource. 334 * @return Status FOUND on success or an error on failure. 335 */ 336 private function parse_ipco( $num_remaining_bytes ) { 337 $box_index = 1; // 1-based index. Used for iterating over properties. 338 do { 339 $box = new Box(); 340 $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes ); 341 if ( $status != FOUND ) { 342 return $status; 343 } 344 345 if ( $box->type == 'ispe' ) { 346 // See ISO/IEC 23008-12:2017(E) 6.5.3.2 347 if ( $box->content_size < 8 ) { 348 return INVALID; 349 } 350 if ( !( $data = read( $this->handle, 8 ) ) ) { 351 return TRUNCATED; 352 } 353 $width = read_big_endian( substr( $data, 0, 4 ), 4 ); 354 $height = read_big_endian( substr( $data, 4, 4 ), 4 ); 355 if ( $width == 0 || $height == 0 ) { 356 return INVALID; 357 } 358 if ( count( $this->features->dim_props ) <= MAX_FEATURES && 359 $box_index <= MAX_VALUE ) { 360 $dim_prop_count = count( $this->features->dim_props ); 361 $this->features->dim_props[$dim_prop_count] = new Dim_Prop(); 362 $this->features->dim_props[$dim_prop_count]->property_index = $box_index; 363 $this->features->dim_props[$dim_prop_count]->width = $width; 364 $this->features->dim_props[$dim_prop_count]->height = $height; 365 } else { 366 $this->data_was_skipped = true; 367 } 368 if ( !skip( $this->handle, $box->content_size - 8 ) ) { 369 return TRUNCATED; 370 } 371 } else if ( $box->type == 'pixi' ) { 372 // See ISO/IEC 23008-12:2017(E) 6.5.6.2 373 if ( $box->content_size < 1 ) { 374 return INVALID; 375 } 376 if ( !( $data = read( $this->handle, 1 ) ) ) { 377 return TRUNCATED; 378 } 379 $num_channels = read_big_endian( $data, 1 ); 380 if ( $num_channels < 1 ) { 381 return INVALID; 382 } 383 if ( $box->content_size < 1 + $num_channels ) { 384 return INVALID; 385 } 386 if ( !( $data = read( $this->handle, 1 ) ) ) { 387 return TRUNCATED; 388 } 389 $bit_depth = read_big_endian( $data, 1 ); 390 if ( $bit_depth < 1 ) { 391 return INVALID; 392 } 393 for ( $i = 1; $i < $num_channels; ++$i ) { 394 if ( !( $data = read( $this->handle, 1 ) ) ) { 395 return TRUNCATED; 396 } 397 // Bit depth should be the same for all channels. 398 if ( read_big_endian( $data, 1 ) != $bit_depth ) { 399 return INVALID; 400 } 401 if ( $i > 32 ) { 402 return ABORTED; // Be reasonable. 403 } 404 } 405 if ( count( $this->features->chan_props ) <= MAX_FEATURES && 406 $box_index <= MAX_VALUE && $bit_depth <= MAX_VALUE && 407 $num_channels <= MAX_VALUE ) { 408 $chan_prop_count = count( $this->features->chan_props ); 409 $this->features->chan_props[$chan_prop_count] = new Chan_Prop(); 410 $this->features->chan_props[$chan_prop_count]->property_index = $box_index; 411 $this->features->chan_props[$chan_prop_count]->bit_depth = $bit_depth; 412 $this->features->chan_props[$chan_prop_count]->num_channels = $num_channels; 413 } else { 414 $this->data_was_skipped = true; 415 } 416 if ( !skip( $this->handle, $box->content_size - ( 1 + $num_channels ) ) ) { 417 return TRUNCATED; 418 } 419 } else if ( $box->type == 'av1C' ) { 420 // See AV1 Codec ISO Media File Format Binding 2.3.1 421 // at https://aomediacodec.github.io/av1-isobmff/#av1c 422 // Only parse the necessary third byte. Assume that the others are valid. 423 if ( $box->content_size < 3 ) { 424 return INVALID; 425 } 426 if ( !( $data = read( $this->handle, 3 ) ) ) { 427 return TRUNCATED; 428 } 429 $byte = read_big_endian( substr( $data, 2, 1 ), 1 ); 430 $high_bitdepth = ( $byte & 0x40 ) != 0; 431 $twelve_bit = ( $byte & 0x20 ) != 0; 432 $monochrome = ( $byte & 0x10 ) != 0; 433 if ( $twelve_bit && !$high_bitdepth ) { 434 return INVALID; 435 } 436 if ( count( $this->features->chan_props ) <= MAX_FEATURES && 437 $box_index <= MAX_VALUE ) { 438 $chan_prop_count = count( $this->features->chan_props ); 439 $this->features->chan_props[$chan_prop_count] = new Chan_Prop(); 440 $this->features->chan_props[$chan_prop_count]->property_index = $box_index; 441 $this->features->chan_props[$chan_prop_count]->bit_depth = 442 $high_bitdepth ? $twelve_bit ? 12 : 10 : 8; 443 $this->features->chan_props[$chan_prop_count]->num_channels = $monochrome ? 1 : 3; 444 } else { 445 $this->data_was_skipped = true; 446 } 447 if ( !skip( $this->handle, $box->content_size - 3 ) ) { 448 return TRUNCATED; 449 } 450 } else if ( $box->type == 'auxC' ) { 451 // See AV1 Image File Format (AVIF) 4 452 // at https://aomediacodec.github.io/av1-avif/#auxiliary-images 453 $kAlphaStr = "urn:mpeg:mpegB:cicp:systems:auxiliary:alpha\0"; 454 $kAlphaStrLength = 44; // Includes terminating character. 455 if ( $box->content_size >= $kAlphaStrLength ) { 456 if ( !( $data = read( $this->handle, $kAlphaStrLength ) ) ) { 457 return TRUNCATED; 458 } 459 if ( substr( $data, 0, $kAlphaStrLength ) == $kAlphaStr ) { 460 // Note: It is unlikely but it is possible that this alpha plane does 461 // not belong to the primary item or a tile. Ignore this issue. 462 $this->features->has_alpha = true; 463 } 464 if ( !skip( $this->handle, $box->content_size - $kAlphaStrLength ) ) { 465 return TRUNCATED; 466 } 467 } else { 468 if ( !skip( $this->handle, $box->content_size ) ) { 469 return TRUNCATED; 470 } 471 } 472 } else { 473 if ( !skip( $this->handle, $box->content_size ) ) { 474 return TRUNCATED; 475 } 476 } 477 ++$box_index; 478 $num_remaining_bytes -= $box->size; 479 } while ( $num_remaining_bytes > 0 ); 480 return NOT_FOUND; 481 } 482 483 /** 484 * Parses an "iprp" box. 485 * 486 * The "ipco" box contain the properties which are linked to items by the "ipma" box. 487 * 488 * @param stream $handle The resource the box will be parsed from. 489 * @param int $num_remaining_bytes The number of bytes that should be available from the resource. 490 * @return Status FOUND on success or an error on failure. 491 */ 492 private function parse_iprp( $num_remaining_bytes ) { 493 do { 494 $box = new Box(); 495 $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes ); 496 if ( $status != FOUND ) { 497 return $status; 498 } 499 500 if ( $box->type == 'ipco' ) { 501 $status = $this->parse_ipco( $box->content_size ); 502 if ( $status != NOT_FOUND ) { 503 return $status; 504 } 505 } else if ( $box->type == 'ipma' ) { 506 // See ISO/IEC 23008-12:2017(E) 9.3.2 507 $num_read_bytes = 4; 508 if ( $box->content_size < $num_read_bytes ) { 509 return INVALID; 510 } 511 if ( !( $data = read( $this->handle, $num_read_bytes ) ) ) { 512 return TRUNCATED; 513 } 514 $entry_count = read_big_endian( $data, 4 ); 515 $id_num_bytes = ( $box->version < 1 ) ? 2 : 4; 516 $index_num_bytes = ( $box->flags & 1 ) ? 2 : 1; 517 $essential_bit_mask = ( $box->flags & 1 ) ? 0x8000 : 0x80; 518 519 for ( $entry = 0; $entry < $entry_count; ++$entry ) { 520 if ( $entry >= MAX_PROPS || 521 count( $this->features->props ) >= MAX_PROPS ) { 522 $this->data_was_skipped = true; 523 break; 524 } 525 $num_read_bytes += $id_num_bytes + 1; 526 if ( $box->content_size < $num_read_bytes ) { 527 return INVALID; 528 } 529 if ( !( $data = read( $this->handle, $id_num_bytes + 1 ) ) ) { 530 return TRUNCATED; 531 } 532 $item_id = read_big_endian( 533 substr( $data, 0, $id_num_bytes ), $id_num_bytes ); 534 $association_count = read_big_endian( 535 substr( $data, $id_num_bytes, 1 ), 1 ); 536 537 for ( $property = 0; $property < $association_count; ++$property ) { 538 if ( $property >= MAX_PROPS || 539 count( $this->features->props ) >= MAX_PROPS ) { 540 $this->data_was_skipped = true; 541 break; 542 } 543 $num_read_bytes += $index_num_bytes; 544 if ( $box->content_size < $num_read_bytes ) { 545 return INVALID; 546 } 547 if ( !( $data = read( $this->handle, $index_num_bytes ) ) ) { 548 return TRUNCATED; 549 } 550 $value = read_big_endian( $data, $index_num_bytes ); 551 // $essential = ($value & $essential_bit_mask); // Unused. 552 $property_index = ( $value & ~$essential_bit_mask ); 553 if ( $property_index <= MAX_VALUE && $item_id <= MAX_VALUE ) { 554 $prop_count = count( $this->features->props ); 555 $this->features->props[$prop_count] = new Prop(); 556 $this->features->props[$prop_count]->property_index = $property_index; 557 $this->features->props[$prop_count]->item_id = $item_id; 558 } else { 559 $this->data_was_skipped = true; 560 } 561 } 562 if ( $property < $association_count ) { 563 break; // Do not read garbage. 564 } 565 } 566 567 // If all features are available now, do not look further. 568 $status = $this->features->get_primary_item_features(); 569 if ( $status != NOT_FOUND ) { 570 return $status; 571 } 572 573 // Mostly if 'data_was_skipped'. 574 if ( !skip( $this->handle, $box->content_size - $num_read_bytes ) ) { 575 return TRUNCATED; 576 } 577 } else { 578 if ( !skip( $this->handle, $box->content_size ) ) { 579 return TRUNCATED; 580 } 581 } 582 $num_remaining_bytes -= $box->size; 583 } while ( $num_remaining_bytes > 0 ); 584 return NOT_FOUND; 585 } 586 587 /** 588 * Parses an "iref" box. 589 * 590 * The "dimg" boxes contain links between tiles and their parent items, which 591 * can be used to infer bit depth and number of channels for the primary item 592 * when the latter does not have these properties. 593 * 594 * @param stream $handle The resource the box will be parsed from. 595 * @param int $num_remaining_bytes The number of bytes that should be available from the resource. 596 * @return Status FOUND on success or an error on failure. 597 */ 598 private function parse_iref( $num_remaining_bytes ) { 599 do { 600 $box = new Box(); 601 $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes ); 602 if ( $status != FOUND ) { 603 return $status; 604 } 605 606 if ( $box->type == 'dimg' ) { 607 // See ISO/IEC 14496-12:2015(E) 8.11.12.2 608 $num_bytes_per_id = ( $box->version == 0 ) ? 2 : 4; 609 $num_read_bytes = $num_bytes_per_id + 2; 610 if ( $box->content_size < $num_read_bytes ) { 611 return INVALID; 612 } 613 if ( !( $data = read( $this->handle, $num_read_bytes ) ) ) { 614 return TRUNCATED; 615 } 616 $from_item_id = read_big_endian( $data, $num_bytes_per_id ); 617 $reference_count = read_big_endian( substr( $data, $num_bytes_per_id, 2 ), 2 ); 618 619 for ( $i = 0; $i < $reference_count; ++$i ) { 620 if ( $i >= MAX_TILES ) { 621 $this->data_was_skipped = true; 622 break; 623 } 624 $num_read_bytes += $num_bytes_per_id; 625 if ( $box->content_size < $num_read_bytes ) { 626 return INVALID; 627 } 628 if ( !( $data = read( $this->handle, $num_bytes_per_id ) ) ) { 629 return TRUNCATED; 630 } 631 $to_item_id = read_big_endian( $data, $num_bytes_per_id ); 632 $tile_count = count( $this->features->tiles ); 633 if ( $from_item_id <= MAX_VALUE && $to_item_id <= MAX_VALUE && 634 $tile_count < MAX_TILES ) { 635 $this->features->tiles[$tile_count] = new Tile(); 636 $this->features->tiles[$tile_count]->tile_item_id = $to_item_id; 637 $this->features->tiles[$tile_count]->parent_item_id = $from_item_id; 638 } else { 639 $this->data_was_skipped = true; 640 } 641 } 642 643 // If all features are available now, do not look further. 644 $status = $this->features->get_primary_item_features(); 645 if ( $status != NOT_FOUND ) { 646 return $status; 647 } 648 649 // Mostly if 'data_was_skipped'. 650 if ( !skip( $this->handle, $box->content_size - $num_read_bytes ) ) { 651 return TRUNCATED; 652 } 653 } else { 654 if ( !skip( $this->handle, $box->content_size ) ) { 655 return TRUNCATED; 656 } 657 } 658 $num_remaining_bytes -= $box->size; 659 } while ( $num_remaining_bytes > 0 ); 660 return NOT_FOUND; 661 } 662 663 /** 664 * Parses a "meta" box. 665 * 666 * It looks for the primary item ID in the "pitm" box and recurses into other boxes 667 * to find its features. 668 * 669 * @param stream $handle The resource the box will be parsed from. 670 * @param int $num_remaining_bytes The number of bytes that should be available from the resource. 671 * @return Status FOUND on success or an error on failure. 672 */ 673 private function parse_meta( $num_remaining_bytes ) { 674 do { 675 $box = new Box(); 676 $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes ); 677 if ( $status != FOUND ) { 678 return $status; 679 } 680 681 if ( $box->type == 'pitm' ) { 682 // See ISO/IEC 14496-12:2015(E) 8.11.4.2 683 $num_bytes_per_id = ( $box->version == 0 ) ? 2 : 4; 684 if ( $num_bytes_per_id > $num_remaining_bytes ) { 685 return INVALID; 686 } 687 if ( !( $data = read( $this->handle, $num_bytes_per_id ) ) ) { 688 return TRUNCATED; 689 } 690 $primary_item_id = read_big_endian( $data, $num_bytes_per_id ); 691 if ( $primary_item_id > MAX_VALUE ) { 692 return ABORTED; 693 } 694 $this->features->has_primary_item = true; 695 $this->features->primary_item_id = $primary_item_id; 696 if ( !skip( $this->handle, $box->content_size - $num_bytes_per_id ) ) { 697 return TRUNCATED; 698 } 699 } else if ( $box->type == 'iprp' ) { 700 $status = $this->parse_iprp( $box->content_size ); 701 if ( $status != NOT_FOUND ) { 702 return $status; 703 } 704 } else if ( $box->type == 'iref' ) { 705 $status = $this->parse_iref( $box->content_size ); 706 if ( $status != NOT_FOUND ) { 707 return $status; 708 } 709 } else { 710 if ( !skip( $this->handle, $box->content_size ) ) { 711 return TRUNCATED; 712 } 713 } 714 $num_remaining_bytes -= $box->size; 715 } while ( $num_remaining_bytes != 0 ); 716 // According to ISO/IEC 14496-12:2012(E) 8.11.1.1 there is at most one "meta". 717 return INVALID; 718 } 719 720 /** 721 * Parses a file stream. 722 * 723 * The file type is checked through the "ftyp" box. 724 * 725 * @return bool True if the input stream is an AVIF bitstream or false. 726 */ 727 public function parse_ftyp() { 728 $box = new Box(); 729 $status = $box->parse( $this->handle, $this->num_parsed_boxes ); 730 if ( $status != FOUND ) { 731 return false; 732 } 733 734 if ( $box->type != 'ftyp' ) { 735 return false; 736 } 737 // Iterate over brands. See ISO/IEC 14496-12:2012(E) 4.3.1 738 if ( $box->content_size < 8 ) { 739 return false; 740 } 741 for ( $i = 0; $i + 4 <= $box->content_size; $i += 4 ) { 742 if ( !( $data = read( $this->handle, 4 ) ) ) { 743 return false; 744 } 745 if ( $i == 4 ) { 746 continue; // Skip minor_version. 747 } 748 if ( substr( $data, 0, 4 ) == 'avif' || substr( $data, 0, 4 ) == 'avis' ) { 749 return skip( $this->handle, $box->content_size - ( $i + 4 ) ); 750 } 751 if ( $i > 32 * 4 ) { 752 return false; // Be reasonable. 753 } 754 755 } 756 return false; // No AVIF brand no good. 757 } 758 759 /** 760 * Parses a file stream. 761 * 762 * Features are extracted from the "meta" box. 763 * 764 * @return bool True if the main features of the primary item were parsed or false. 765 */ 766 public function parse_file() { 767 $box = new Box(); 768 while ( $box->parse( $this->handle, $this->num_parsed_boxes ) == FOUND ) { 769 if ( $box->type === 'meta' ) { 770 if ( $this->parse_meta( $box->content_size ) != FOUND ) { 771 return false; 772 } 773 return true; 774 } 775 if ( !skip( $this->handle, $box->content_size ) ) { 776 return false; 777 } 778 } 779 return false; // No "meta" no good. 780 } 781 }
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| Generated : Sat Dec 21 08:20:01 2024 | Cross-referenced by PHPXref |