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 // Internal header for constants related to WebP file format. 9 // 10 // Author: Urvang (urvang@google.com) 11 12 #ifndef WEBP_WEBP_FORMAT_CONSTANTS_H_ 13 #define WEBP_WEBP_FORMAT_CONSTANTS_H_ 14 15 // VP8 related constants. 16 #define VP8_SIGNATURE 0x9d012a // Signature in VP8 data. 17 #define VP8_MAX_PARTITION0_SIZE (1 << 19) // max size of mode partition 18 #define VP8_MAX_PARTITION_SIZE (1 << 24) // max size for token partition 19 #define VP8_FRAME_HEADER_SIZE 10 // Size of the frame header within VP8 data. 20 21 // VP8L related constants. 22 #define VP8L_SIGNATURE_SIZE 1 // VP8L signature size. 23 #define VP8L_MAGIC_BYTE 0x2f // VP8L signature byte. 24 #define VP8L_IMAGE_SIZE_BITS 14 // Number of bits used to store 25 // width and height. 26 #define VP8L_VERSION_BITS 3 // 3 bits reserved for version. 27 #define VP8L_VERSION 0 // version 0 28 #define VP8L_FRAME_HEADER_SIZE 5 // Size of the VP8L frame header. 29 30 #define MAX_PALETTE_SIZE 256 31 #define MAX_CACHE_BITS 11 32 #define HUFFMAN_CODES_PER_META_CODE 5 33 #define ARGB_BLACK 0xff000000 34 35 #define DEFAULT_CODE_LENGTH 8 36 #define MAX_ALLOWED_CODE_LENGTH 15 37 38 #define NUM_LITERAL_CODES 256 39 #define NUM_LENGTH_CODES 24 40 #define NUM_DISTANCE_CODES 40 41 #define CODE_LENGTH_CODES 19 42 43 #define MIN_HUFFMAN_BITS 2 // min number of Huffman bits 44 #define MAX_HUFFMAN_BITS 9 // max number of Huffman bits 45 46 #define TRANSFORM_PRESENT 1 // The bit to be written when next data 47 // to be read is a transform. 48 #define NUM_TRANSFORMS 4 // Maximum number of allowed transform 49 // in a bitstream. 50 typedef enum { 51 PREDICTOR_TRANSFORM = 0, 52 CROSS_COLOR_TRANSFORM = 1, 53 SUBTRACT_GREEN = 2, 54 COLOR_INDEXING_TRANSFORM = 3 55 } VP8LImageTransformType; 56 57 // Alpha related constants. 58 #define ALPHA_HEADER_LEN 1 59 #define ALPHA_NO_COMPRESSION 0 60 #define ALPHA_LOSSLESS_COMPRESSION 1 61 #define ALPHA_PREPROCESSED_LEVELS 1 62 63 // Mux related constants. 64 #define TAG_SIZE 4 // Size of a chunk tag (e.g. "VP8L"). 65 #define CHUNK_SIZE_BYTES 4 // Size needed to store chunk's size. 66 #define CHUNK_HEADER_SIZE 8 // Size of a chunk header. 67 #define RIFF_HEADER_SIZE 12 // Size of the RIFF header ("RIFFnnnnWEBP"). 68 #define ANMF_CHUNK_SIZE 16 // Size of an ANMF chunk. 69 #define ANIM_CHUNK_SIZE 6 // Size of an ANIM chunk. 70 #define FRGM_CHUNK_SIZE 6 // Size of a FRGM chunk. 71 #define VP8X_CHUNK_SIZE 10 // Size of a VP8X chunk. 72 73 // VP8X Feature Flags. 74 #if !(defined(__cplusplus) || defined(c_plusplus)) 75 typedef enum WebPFeatureFlags WebPFeatureFlags; 76 #endif 77 enum WebPFeatureFlags { 78 FRAGMENTS_FLAG = 0x00000001, 79 ANIMATION_FLAG = 0x00000002, 80 XMP_FLAG = 0x00000004, 81 EXIF_FLAG = 0x00000008, 82 ALPHA_FLAG = 0x00000010, 83 ICCP_FLAG = 0x00000020 84 }; 85 86 #define MAX_CANVAS_SIZE (1 << 24) // 24-bit max for VP8X width/height. 87 #define MAX_IMAGE_AREA (1ULL << 32) // 32-bit max for width x height. 88 #define MAX_LOOP_COUNT (1 << 16) // maximum value for loop-count 89 #define MAX_DURATION (1 << 24) // maximum duration 90 #define MAX_POSITION_OFFSET (1 << 24) // maximum frame/fragment x/y offset 91 92 // Maximum chunk payload is such that adding the header and padding won't 93 // overflow a uint32_t. 94 #define MAX_CHUNK_PAYLOAD (~0U - CHUNK_HEADER_SIZE - 1) 95 96 #endif /* WEBP_WEBP_FORMAT_CONSTANTS_H_ */ 97