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// Copyright 2012 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// Internal header for constants related to WebP file format.
//
// Author: Urvang (urvang@google.com)
#ifndef WEBP_WEBP_FORMAT_CONSTANTS_H_
#define WEBP_WEBP_FORMAT_CONSTANTS_H_
// Create fourcc of the chunk from the chunk tag characters.
#define MKFOURCC(a, b, c, d) ((a) | (b) << 8 | (c) << 16 | (uint32_t)(d) << 24)
// VP8 related constants.
#define VP8_SIGNATURE 0x9d012a // Signature in VP8 data.
#define VP8_MAX_PARTITION0_SIZE (1 << 19) // max size of mode partition
#define VP8_MAX_PARTITION_SIZE (1 << 24) // max size for token partition
#define VP8_FRAME_HEADER_SIZE 10 // Size of the frame header within VP8 data.
// VP8L related constants.
#define VP8L_SIGNATURE_SIZE 1 // VP8L signature size.
#define VP8L_MAGIC_BYTE 0x2f // VP8L signature byte.
#define VP8L_IMAGE_SIZE_BITS 14 // Number of bits used to store
// width and height.
#define VP8L_VERSION_BITS 3 // 3 bits reserved for version.
#define VP8L_VERSION 0 // version 0
#define VP8L_FRAME_HEADER_SIZE 5 // Size of the VP8L frame header.
#define MAX_PALETTE_SIZE 256
#define MAX_CACHE_BITS 11
#define HUFFMAN_CODES_PER_META_CODE 5
#define ARGB_BLACK 0xff000000
#define DEFAULT_CODE_LENGTH 8
#define MAX_ALLOWED_CODE_LENGTH 15
#define NUM_LITERAL_CODES 256
#define NUM_LENGTH_CODES 24
#define NUM_DISTANCE_CODES 40
#define CODE_LENGTH_CODES 19
#define MIN_HUFFMAN_BITS 2 // min number of Huffman bits
#define MAX_HUFFMAN_BITS 9 // max number of Huffman bits
#define TRANSFORM_PRESENT 1 // The bit to be written when next data
// to be read is a transform.
#define NUM_TRANSFORMS 4 // Maximum number of allowed transform
// in a bitstream.
typedef enum {
PREDICTOR_TRANSFORM = 0,
CROSS_COLOR_TRANSFORM = 1,
SUBTRACT_GREEN = 2,
COLOR_INDEXING_TRANSFORM = 3
} VP8LImageTransformType;
// Alpha related constants.
#define ALPHA_HEADER_LEN 1
#define ALPHA_NO_COMPRESSION 0
#define ALPHA_LOSSLESS_COMPRESSION 1
#define ALPHA_PREPROCESSED_LEVELS 1
// Mux related constants.
#define TAG_SIZE 4 // Size of a chunk tag (e.g. "VP8L").
#define CHUNK_SIZE_BYTES 4 // Size needed to store chunk's size.
#define CHUNK_HEADER_SIZE 8 // Size of a chunk header.
#define RIFF_HEADER_SIZE 12 // Size of the RIFF header ("RIFFnnnnWEBP").
#define ANMF_CHUNK_SIZE 16 // Size of an ANMF chunk.
#define ANIM_CHUNK_SIZE 6 // Size of an ANIM chunk.
#define VP8X_CHUNK_SIZE 10 // Size of a VP8X chunk.
#define MAX_CANVAS_SIZE (1 << 24) // 24-bit max for VP8X width/height.
#define MAX_IMAGE_AREA (1ULL << 32) // 32-bit max for width x height.
#define MAX_LOOP_COUNT (1 << 16) // maximum value for loop-count
#define MAX_DURATION (1 << 24) // maximum duration
#define MAX_POSITION_OFFSET (1 << 24) // maximum frame x/y offset
// Maximum chunk payload is such that adding the header and padding won't
// overflow a uint32_t.
#define MAX_CHUNK_PAYLOAD (~0U - CHUNK_HEADER_SIZE - 1)
#endif /* WEBP_WEBP_FORMAT_CONSTANTS_H_ */
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