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47 lines
1.6 KiB
47 lines
1.6 KiB
// Copyright 2011 Google Inc. All Rights Reserved. |
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// |
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// This code is licensed under the same terms as WebM: |
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// Software License Agreement: http://www.webmproject.org/license/software/ |
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// Additional IP Rights Grant: http://www.webmproject.org/license/additional/ |
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// ----------------------------------------------------------------------------- |
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// |
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// Author: Jyrki Alakuijala (jyrki@google.com) |
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// |
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// Entropy encoding (Huffman) for webp lossless |
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#ifndef WEBP_UTILS_HUFFMAN_ENCODE_H_ |
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#define WEBP_UTILS_HUFFMAN_ENCODE_H_ |
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#include "../webp/types.h" |
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#if defined(__cplusplus) || defined(c_plusplus) |
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extern "C" { |
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#endif |
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// Struct for holding the tree header in coded form. |
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typedef struct { |
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uint8_t code; // value (0..15) or escape code (16,17,18) |
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uint8_t extra_bits; // extra bits for escape codes |
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} HuffmanTreeToken; |
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// Struct to represent the tree codes (depth and bits array). |
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typedef struct { |
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int num_symbols; // Number of symbols. |
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uint8_t* code_lengths; // Code lengths of the symbols. |
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uint16_t* codes; // Symbol Codes. |
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} HuffmanTreeCode; |
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// Turn the Huffman tree into a token sequence. |
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// Returns the number of tokens used. |
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int VP8LCreateCompressedHuffmanTree(const HuffmanTreeCode* const tree, |
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HuffmanTreeToken* tokens, int max_tokens); |
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// Create an optimized tree, and tokenize it. |
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int VP8LCreateHuffmanTree(int* const histogram, int tree_depth_limit, |
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HuffmanTreeCode* const tree); |
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#if defined(__cplusplus) || defined(c_plusplus) |
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} |
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#endif |
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#endif // WEBP_UTILS_HUFFMAN_ENCODE_H_
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