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