prob.h 3.19 KB
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/*
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 *  Copyright (c) 2013 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
 *  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 VPX_DSP_PROB_H_
#define VPX_DSP_PROB_H_
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#include "./vpx_config.h"
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#include "./vpx_dsp_common.h"
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#include "vpx_ports/mem.h"

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#ifdef __cplusplus
extern "C" {
#endif

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typedef uint8_t vp9_prob;
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#define MAX_PROB 255

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#define vp9_prob_half ((vp9_prob) 128)
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typedef int8_t vp9_tree_index;
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#define TREE_SIZE(leaf_count) (2 * (leaf_count) - 2)

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#define vp9_complement(x) (255 - x)
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#define MODE_MV_COUNT_SAT 20

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/* We build coding trees compactly in arrays.
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   Each node of the tree is a pair of vp9_tree_indices.
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   Array index often references a corresponding probability table.
   Index <= 0 means done encoding/decoding and value = -Index,
   Index > 0 means need another bit, specification at index.
   Nonnegative indices are always even;  processing begins at node 0. */

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typedef const vp9_tree_index vp9_tree[];
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static INLINE vp9_prob clip_prob(int p) {
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  return (p > 255) ? 255 : (p < 1) ? 1 : p;
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}

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static INLINE vp9_prob get_prob(int num, int den) {
  return (den == 0) ? 128u : clip_prob(((int64_t)num * 256 + (den >> 1)) / den);
}
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static INLINE vp9_prob get_binary_prob(int n0, int n1) {
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  return get_prob(n0, n0 + n1);
}

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/* This function assumes prob1 and prob2 are already within [1,255] range. */
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static INLINE vp9_prob weighted_prob(int prob1, int prob2, int factor) {
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  return ROUND_POWER_OF_TWO(prob1 * (256 - factor) + prob2 * factor, 8);
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}
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static INLINE vp9_prob merge_probs(vp9_prob pre_prob,
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                                   const unsigned int ct[2],
                                   unsigned int count_sat,
                                   unsigned int max_update_factor) {
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  const vp9_prob prob = get_binary_prob(ct[0], ct[1]);
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  const unsigned int count = MIN(ct[0] + ct[1], count_sat);
  const unsigned int factor = max_update_factor * count / count_sat;
  return weighted_prob(pre_prob, prob, factor);
}

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// MODE_MV_MAX_UPDATE_FACTOR (128) * count / MODE_MV_COUNT_SAT;
static const int count_to_update_factor[MODE_MV_COUNT_SAT + 1] = {
  0, 6, 12, 19, 25, 32, 38, 44, 51, 57, 64,
  70, 76, 83, 89, 96, 102, 108, 115, 121, 128
};

static INLINE vp9_prob mode_mv_merge_probs(vp9_prob pre_prob,
                                           const unsigned int ct[2]) {
  const unsigned int den = ct[0] + ct[1];
  if (den == 0) {
    return pre_prob;
  } else {
    const unsigned int count = MIN(den, MODE_MV_COUNT_SAT);
    const unsigned int factor = count_to_update_factor[count];
    const vp9_prob prob =
        clip_prob(((int64_t)(ct[0]) * 256 + (den >> 1)) / den);
    return weighted_prob(pre_prob, prob, factor);
  }
}

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void vp9_tree_merge_probs(const vp9_tree_index *tree, const vp9_prob *pre_probs,
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                          const unsigned int *counts, vp9_prob *probs);
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DECLARE_ALIGNED(16, extern const uint8_t, vp9_norm[256]);
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#ifdef __cplusplus
}  // extern "C"
#endif

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#endif  // VPX_DSP_PROB_H_