1// Copyright 2012 Google Inc. All Rights Reserved. 2// 3// Use of this source code is governed by a BSD-style license 4// that can be found in the COPYING file in the root of the source 5// tree. An additional intellectual property rights grant can be found 6// in the file PATENTS. All contributing project authors may 7// be found in the AUTHORS file in the root of the source tree. 8// ----------------------------------------------------------------------------- 9// 10// Internal header for constants related to WebP file format. 11// 12// Author: Urvang (urvang@google.com) 13 14#ifndef WEBP_WEBP_FORMAT_CONSTANTS_H_ 15#define WEBP_WEBP_FORMAT_CONSTANTS_H_ 16 17// Create fourcc of the chunk from the chunk tag characters. 18#define MKFOURCC(a, b, c, d) ((uint32_t)(a) | (b) << 8 | (c) << 16 | (d) << 24) 19 20// VP8 related constants. 21#define VP8_SIGNATURE 0x9d012a // Signature in VP8 data. 22#define VP8_MAX_PARTITION0_SIZE (1 << 19) // max size of mode partition 23#define VP8_MAX_PARTITION_SIZE (1 << 24) // max size for token partition 24#define VP8_FRAME_HEADER_SIZE 10 // Size of the frame header within VP8 data. 25 26// VP8L related constants. 27#define VP8L_SIGNATURE_SIZE 1 // VP8L signature size. 28#define VP8L_MAGIC_BYTE 0x2f // VP8L signature byte. 29#define VP8L_IMAGE_SIZE_BITS 14 // Number of bits used to store 30 // width and height. 31#define VP8L_VERSION_BITS 3 // 3 bits reserved for version. 32#define VP8L_VERSION 0 // version 0 33#define VP8L_FRAME_HEADER_SIZE 5 // Size of the VP8L frame header. 34 35#define MAX_PALETTE_SIZE 256 36#define MAX_CACHE_BITS 11 37#define HUFFMAN_CODES_PER_META_CODE 5 38#define ARGB_BLACK 0xff000000 39 40#define DEFAULT_CODE_LENGTH 8 41#define MAX_ALLOWED_CODE_LENGTH 15 42 43#define NUM_LITERAL_CODES 256 44#define NUM_LENGTH_CODES 24 45#define NUM_DISTANCE_CODES 40 46#define CODE_LENGTH_CODES 19 47 48#define MIN_HUFFMAN_BITS 2 // min number of Huffman bits 49#define MAX_HUFFMAN_BITS 9 // max number of Huffman bits 50 51#define TRANSFORM_PRESENT 1 // The bit to be written when next data 52 // to be read is a transform. 53#define NUM_TRANSFORMS 4 // Maximum number of allowed transform 54 // in a bitstream. 55typedef enum { 56 PREDICTOR_TRANSFORM = 0, 57 CROSS_COLOR_TRANSFORM = 1, 58 SUBTRACT_GREEN = 2, 59 COLOR_INDEXING_TRANSFORM = 3 60} VP8LImageTransformType; 61 62// Alpha related constants. 63#define ALPHA_HEADER_LEN 1 64#define ALPHA_NO_COMPRESSION 0 65#define ALPHA_LOSSLESS_COMPRESSION 1 66#define ALPHA_PREPROCESSED_LEVELS 1 67 68// Mux related constants. 69#define TAG_SIZE 4 // Size of a chunk tag (e.g. "VP8L"). 70#define CHUNK_SIZE_BYTES 4 // Size needed to store chunk's size. 71#define CHUNK_HEADER_SIZE 8 // Size of a chunk header. 72#define RIFF_HEADER_SIZE 12 // Size of the RIFF header ("RIFFnnnnWEBP"). 73#define ANMF_CHUNK_SIZE 16 // Size of an ANMF chunk. 74#define ANIM_CHUNK_SIZE 6 // Size of an ANIM chunk. 75#define FRGM_CHUNK_SIZE 6 // Size of a FRGM chunk. 76#define VP8X_CHUNK_SIZE 10 // Size of a VP8X chunk. 77 78#define MAX_CANVAS_SIZE (1 << 24) // 24-bit max for VP8X width/height. 79#define MAX_IMAGE_AREA (1ULL << 32) // 32-bit max for width x height. 80#define MAX_LOOP_COUNT (1 << 16) // maximum value for loop-count 81#define MAX_DURATION (1 << 24) // maximum duration 82#define MAX_POSITION_OFFSET (1 << 24) // maximum frame/fragment x/y offset 83 84// Maximum chunk payload is such that adding the header and padding won't 85// overflow a uint32_t. 86#define MAX_CHUNK_PAYLOAD (~0U - CHUNK_HEADER_SIZE - 1) 87 88#endif /* WEBP_WEBP_FORMAT_CONSTANTS_H_ */ 89