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