vpx_dsp/prob.h

   1 /*
   2  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #ifndef VPX_DSP_PROB_H_
  12 #define VPX_DSP_PROB_H_
  13
  14 #include "./vpx_config.h"
  15 #include "./vpx_dsp_common.h"
  16
  17 #include "vpx_ports/mem.h"
  18
  19 #ifdef __cplusplus
  20 extern "C" {
  21 #endif
  22
  23 typedef uint8_t vpx_prob;
  24
  25 #define MAX_PROB 255
  26
  27 #define vpx_prob_half ((vpx_prob) 128)
  28
  29 typedef int8_t vpx_tree_index;
  30
  31 #define TREE_SIZE(leaf_count) (2 * (leaf_count) - 2)
  32
  33 #define vpx_complement(x) (255 - x)
  34
  35 #define MODE_MV_COUNT_SAT 20
  36
  37 /* We build coding trees compactly in arrays.
  38    Each node of the tree is a pair of vpx_tree_indices.
  39    Array index often references a corresponding probability table.
  40    Index <= 0 means done encoding/decoding and value = -Index,
  41    Index > 0 means need another bit, specification at index.
  42    Nonnegative indices are always even;  processing begins at node 0. */
  43
  44 typedef const vpx_tree_index vpx_tree[];
  45
  46 static INLINE vpx_prob clip_prob(int p) {
  47   return (p > 255) ? 255 : (p < 1) ? 1 : p;
  48 }
  49
  50 static INLINE vpx_prob get_prob(int num, int den) {
  51   return (den == 0) ? 128u : clip_prob(((int64_t)num * 256 + (den >> 1)) / den);
  52 }
  53
  54 static INLINE vpx_prob get_binary_prob(int n0, int n1) {
  55   return get_prob(n0, n0 + n1);
  56 }
  57
  58 /* This function assumes prob1 and prob2 are already within [1,255] range. */
  59 static INLINE vpx_prob weighted_prob(int prob1, int prob2, int factor) {
  60   return ROUND_POWER_OF_TWO(prob1 * (256 - factor) + prob2 * factor, 8);
  61 }
  62
  63 static INLINE vpx_prob merge_probs(vpx_prob pre_prob,
  64                                    const unsigned int ct[2],
  65                                    unsigned int count_sat,
  66                                    unsigned int max_update_factor) {
  67   const vpx_prob prob = get_binary_prob(ct[0], ct[1]);
  68   const unsigned int count = VPXMIN(ct[0] + ct[1], count_sat);
  69   const unsigned int factor = max_update_factor * count / count_sat;
  70   return weighted_prob(pre_prob, prob, factor);
  71 }
  72
  73 // MODE_MV_MAX_UPDATE_FACTOR (128) * count / MODE_MV_COUNT_SAT;
  74 static const int count_to_update_factor[MODE_MV_COUNT_SAT + 1] = {
  75   0, 6, 12, 19, 25, 32, 38, 44, 51, 57, 64,
  76   70, 76, 83, 89, 96, 102, 108, 115, 121, 128
  77 };
  78
  79 static INLINE vpx_prob mode_mv_merge_probs(vpx_prob pre_prob,
  80                                            const unsigned int ct[2]) {
  81   const unsigned int den = ct[0] + ct[1];
  82   if (den == 0) {
  83     return pre_prob;
  84   } else {
  85     const unsigned int count = VPXMIN(den, MODE_MV_COUNT_SAT);
  86     const unsigned int factor = count_to_update_factor[count];
  87     const vpx_prob prob =
  88         clip_prob(((int64_t)(ct[0]) * 256 + (den >> 1)) / den);
  89     return weighted_prob(pre_prob, prob, factor);
  90   }
  91 }
  92
  93 void vpx_tree_merge_probs(const vpx_tree_index *tree, const vpx_prob *pre_probs,
  94                           const unsigned int *counts, vpx_prob *probs);
  95
  96
  97 DECLARE_ALIGNED(16, extern const uint8_t, vpx_norm[256]);
  98
  99 #ifdef __cplusplus
 100 }  // extern "C"
 101 #endif
 102
 103 #endif  // VPX_DSP_PROB_H_