99 lines
2.8 KiB
C
99 lines
2.8 KiB
C
/*
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* Copyright (c) 2010 The WebM project authors. 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 LICENSE 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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#ifndef VP8_COMMON_TREECODER_H_
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#define VP8_COMMON_TREECODER_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef unsigned char vp8bc_index_t; /* probability index */
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typedef unsigned char vp8_prob;
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#define vp8_prob_half ( (vp8_prob) 128)
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typedef signed char vp8_tree_index;
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struct bool_coder_spec;
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typedef struct bool_coder_spec bool_coder_spec;
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typedef struct bool_writer bool_writer;
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typedef struct bool_reader bool_reader;
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typedef const bool_coder_spec c_bool_coder_spec;
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typedef const bool_writer c_bool_writer;
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typedef const bool_reader c_bool_reader;
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# define vp8_complement( x) (255 - x)
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/* We build coding trees compactly in arrays.
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Each node of the tree is a pair of vp8_tree_indices.
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Array index often references a corresponding probability table.
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Index <= 0 means done encoding/decoding and value = -Index,
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Index > 0 means need another bit, specification at index.
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Nonnegative indices are always even; processing begins at node 0. */
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typedef const vp8_tree_index vp8_tree[], *vp8_tree_p;
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typedef const struct vp8_token_struct
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{
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int value;
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int Len;
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} vp8_token;
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/* Construct encoding array from tree. */
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void vp8_tokens_from_tree(struct vp8_token_struct *, vp8_tree);
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void vp8_tokens_from_tree_offset(struct vp8_token_struct *, vp8_tree,
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int offset);
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/* Convert array of token occurrence counts into a table of probabilities
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for the associated binary encoding tree. Also writes count of branches
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taken for each node on the tree; this facilitiates decisions as to
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probability updates. */
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void vp8_tree_probs_from_distribution(
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int n, /* n = size of alphabet */
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vp8_token tok [ /* n */ ],
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vp8_tree tree,
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vp8_prob probs [ /* n-1 */ ],
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unsigned int branch_ct [ /* n-1 */ ] [2],
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const unsigned int num_events[ /* n */ ],
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unsigned int Pfactor,
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int Round
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);
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/* Variant of above using coder spec rather than hardwired 8-bit probs. */
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void vp8bc_tree_probs_from_distribution(
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int n, /* n = size of alphabet */
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vp8_token tok [ /* n */ ],
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vp8_tree tree,
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vp8_prob probs [ /* n-1 */ ],
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unsigned int branch_ct [ /* n-1 */ ] [2],
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const unsigned int num_events[ /* n */ ],
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c_bool_coder_spec *s
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);
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif // VP8_COMMON_TREECODER_H_
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