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| 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 FRAME_CHUNK_SIZE 15 // Size of a FRM chunk. |
| 69 #define LOOP_CHUNK_SIZE 2 // Size of a LOOP chunk. |
| 70 #define TILE_CHUNK_SIZE 6 // Size of a TILE chunk. |
| 71 #define VP8X_CHUNK_SIZE 10 // Size of a VP8X chunk. |
| 72 |
| 73 #define TILING_FLAG_BIT 0x01 // Set if tiles are possibly used. |
| 74 #define ANIMATION_FLAG_BIT 0x02 // Set if some animation is expected |
| 75 #define ICC_FLAG_BIT 0x04 // Whether ICC is present or not. |
| 76 #define METADATA_FLAG_BIT 0x08 // Set if some META chunk is possibly present. |
| 77 #define ALPHA_FLAG_BIT 0x10 // Should be same as the ALPHA_FLAG in mux.h |
| 78 #define ROTATION_FLAG_BITS 0xe0 // all 3 bits for rotation + symmetry |
| 79 |
| 80 #define MAX_CANVAS_SIZE (1 << 24) // 24-bit max for VP8X width/height. |
| 81 #define MAX_IMAGE_AREA (1ULL << 32) // 32-bit max for width x height. |
| 82 #define MAX_LOOP_COUNT (1 << 16) // maximum value for loop-count |
| 83 #define MAX_DURATION (1 << 24) // maximum duration |
| 84 #define MAX_POSITION_OFFSET (1 << 24) // maximum frame/tile x/y offset |
| 85 |
| 86 // Maximum chunk payload is such that adding the header and padding won't |
| 87 // overflow a uint32_t. |
| 88 #define MAX_CHUNK_PAYLOAD (~0U - CHUNK_HEADER_SIZE - 1) |
| 89 |
| 90 #endif /* WEBP_WEBP_FORMAT_CONSTANTS_H_ */ |
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