James Zern | 9e80ee9 | 2015-03-17 18:54:21 -0700 | [diff] [blame] | 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. |
| 55 | typedef 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_ */ |