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) ((a) | (b) << 8 | (c) << 16 | (uint32_t)(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 VP8X_CHUNK_SIZE 10 // Size of a VP8X chunk.
76
77#define MAX_CANVAS_SIZE (1 << 24) // 24-bit max for VP8X width/height.
78#define MAX_IMAGE_AREA (1ULL << 32) // 32-bit max for width x height.
79#define MAX_LOOP_COUNT (1 << 16) // maximum value for loop-count
80#define MAX_DURATION (1 << 24) // maximum duration
81#define MAX_POSITION_OFFSET (1 << 24) // maximum frame x/y offset
82
83// Maximum chunk payload is such that adding the header and padding won't
84// overflow a uint32_t.
85#define MAX_CHUNK_PAYLOAD (~0U - CHUNK_HEADER_SIZE - 1)
86
87#endif /* WEBP_WEBP_FORMAT_CONSTANTS_H_ */
88