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 #include "vpx_dsp/bitwriter.h"
11
12 #include "vp9/common/vp9_common.h"
13 #include "vp9/common/vp9_entropy.h"
14 #include "vp9/encoder/vp9_cost.h"
15 #include "vp9/encoder/vp9_subexp.h"
16
17 static const uint8_t update_bits[255] = {
18 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6,
19 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 8, 8, 8, 8, 8, 8,
20 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
21 8, 8, 8, 8, 8, 8, 8, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
22 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
23 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
24 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11,
25 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
26 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
27 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
28 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
29 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
30 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
31 11, 11, 11, 11, 11, 11, 11, 0,
32 };
33 #define MIN_DELP_BITS 5
34
recenter_nonneg(int v,int m)35 static int recenter_nonneg(int v, int m) {
36 if (v > (m << 1))
37 return v;
38 else if (v >= m)
39 return ((v - m) << 1);
40 else
41 return ((m - v) << 1) - 1;
42 }
43
remap_prob(int v,int m)44 static int remap_prob(int v, int m) {
45 int i;
46 static const uint8_t map_table[MAX_PROB - 1] = {
47 // generated by:
48 // map_table[j] = split_index(j, MAX_PROB - 1, MODULUS_PARAM);
49 20, 21, 22, 23, 24, 25, 0, 26, 27, 28, 29, 30, 31, 32, 33,
50 34, 35, 36, 37, 1, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
51 48, 49, 2, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
52 3, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 4, 74,
53 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 5, 86, 87, 88,
54 89, 90, 91, 92, 93, 94, 95, 96, 97, 6, 98, 99, 100, 101, 102,
55 103, 104, 105, 106, 107, 108, 109, 7, 110, 111, 112, 113, 114, 115, 116,
56 117, 118, 119, 120, 121, 8, 122, 123, 124, 125, 126, 127, 128, 129, 130,
57 131, 132, 133, 9, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144,
58 145, 10, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 11,
59 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 12, 170, 171,
60 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 13, 182, 183, 184, 185,
61 186, 187, 188, 189, 190, 191, 192, 193, 14, 194, 195, 196, 197, 198, 199,
62 200, 201, 202, 203, 204, 205, 15, 206, 207, 208, 209, 210, 211, 212, 213,
63 214, 215, 216, 217, 16, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227,
64 228, 229, 17, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241,
65 18, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 19,
66 };
67 v--;
68 m--;
69 if ((m << 1) <= MAX_PROB)
70 i = recenter_nonneg(v, m) - 1;
71 else
72 i = recenter_nonneg(MAX_PROB - 1 - v, MAX_PROB - 1 - m) - 1;
73
74 assert(i >= 0 && (size_t)i < sizeof(map_table));
75 i = map_table[i];
76 return i;
77 }
78
prob_diff_update_cost(vpx_prob newp,vpx_prob oldp)79 static int prob_diff_update_cost(vpx_prob newp, vpx_prob oldp) {
80 int delp = remap_prob(newp, oldp);
81 return update_bits[delp] << VP9_PROB_COST_SHIFT;
82 }
83
encode_uniform(vpx_writer * w,int v)84 static void encode_uniform(vpx_writer *w, int v) {
85 const int l = 8;
86 const int m = (1 << l) - 191;
87 if (v < m) {
88 vpx_write_literal(w, v, l - 1);
89 } else {
90 vpx_write_literal(w, m + ((v - m) >> 1), l - 1);
91 vpx_write_literal(w, (v - m) & 1, 1);
92 }
93 }
94
write_bit_gte(vpx_writer * w,int word,int test)95 static INLINE int write_bit_gte(vpx_writer *w, int word, int test) {
96 vpx_write_literal(w, word >= test, 1);
97 return word >= test;
98 }
99
encode_term_subexp(vpx_writer * w,int word)100 static void encode_term_subexp(vpx_writer *w, int word) {
101 if (!write_bit_gte(w, word, 16)) {
102 vpx_write_literal(w, word, 4);
103 } else if (!write_bit_gte(w, word, 32)) {
104 vpx_write_literal(w, word - 16, 4);
105 } else if (!write_bit_gte(w, word, 64)) {
106 vpx_write_literal(w, word - 32, 5);
107 } else {
108 encode_uniform(w, word - 64);
109 }
110 }
111
vp9_write_prob_diff_update(vpx_writer * w,vpx_prob newp,vpx_prob oldp)112 void vp9_write_prob_diff_update(vpx_writer *w, vpx_prob newp, vpx_prob oldp) {
113 const int delp = remap_prob(newp, oldp);
114 encode_term_subexp(w, delp);
115 }
116
vp9_prob_diff_update_savings_search(const unsigned int * ct,vpx_prob oldp,vpx_prob * bestp,vpx_prob upd)117 int64_t vp9_prob_diff_update_savings_search(const unsigned int *ct,
118 vpx_prob oldp, vpx_prob *bestp,
119 vpx_prob upd) {
120 const int64_t old_b = cost_branch256(ct, oldp);
121 int64_t bestsavings = 0;
122 vpx_prob newp, bestnewp = oldp;
123 const int step = *bestp > oldp ? -1 : 1;
124 const int upd_cost = vp9_cost_one(upd) - vp9_cost_zero(upd);
125
126 if (old_b > upd_cost + (MIN_DELP_BITS << VP9_PROB_COST_SHIFT)) {
127 for (newp = *bestp; newp != oldp; newp += step) {
128 const int64_t new_b = cost_branch256(ct, newp);
129 const int64_t update_b = prob_diff_update_cost(newp, oldp) + upd_cost;
130 const int64_t savings = old_b - new_b - update_b;
131 if (savings > bestsavings) {
132 bestsavings = savings;
133 bestnewp = newp;
134 }
135 }
136 }
137 *bestp = bestnewp;
138 return bestsavings;
139 }
140
vp9_prob_diff_update_savings_search_model(const unsigned int * ct,const vpx_prob oldp,vpx_prob * bestp,vpx_prob upd,int stepsize)141 int64_t vp9_prob_diff_update_savings_search_model(const unsigned int *ct,
142 const vpx_prob oldp,
143 vpx_prob *bestp, vpx_prob upd,
144 int stepsize) {
145 int64_t i, old_b, new_b, update_b, savings, bestsavings;
146 int64_t newp;
147 const int64_t step_sign = *bestp > oldp ? -1 : 1;
148 const int64_t step = stepsize * step_sign;
149 const int64_t upd_cost = vp9_cost_one(upd) - vp9_cost_zero(upd);
150 const vpx_prob *newplist, *oldplist;
151 vpx_prob bestnewp;
152 oldplist = vp9_pareto8_full[oldp - 1];
153 old_b = cost_branch256(ct + 2 * PIVOT_NODE, oldp);
154 for (i = UNCONSTRAINED_NODES; i < ENTROPY_NODES; ++i)
155 old_b += cost_branch256(ct + 2 * i, oldplist[i - UNCONSTRAINED_NODES]);
156
157 bestsavings = 0;
158 bestnewp = oldp;
159
160 assert(stepsize > 0);
161
162 if (old_b > upd_cost + (MIN_DELP_BITS << VP9_PROB_COST_SHIFT)) {
163 for (newp = *bestp; (newp - oldp) * step_sign < 0; newp += step) {
164 if (newp < 1 || newp > 255) continue;
165 newplist = vp9_pareto8_full[newp - 1];
166 new_b = cost_branch256(ct + 2 * PIVOT_NODE, (vpx_prob)newp);
167 for (i = UNCONSTRAINED_NODES; i < ENTROPY_NODES; ++i)
168 new_b += cost_branch256(ct + 2 * i, newplist[i - UNCONSTRAINED_NODES]);
169 update_b = prob_diff_update_cost((vpx_prob)newp, oldp) + upd_cost;
170 savings = old_b - new_b - update_b;
171 if (savings > bestsavings) {
172 bestsavings = savings;
173 bestnewp = (vpx_prob)newp;
174 }
175 }
176 }
177
178 *bestp = bestnewp;
179 return bestsavings;
180 }
181
vp9_cond_prob_diff_update(vpx_writer * w,vpx_prob * oldp,const unsigned int ct[2])182 void vp9_cond_prob_diff_update(vpx_writer *w, vpx_prob *oldp,
183 const unsigned int ct[2]) {
184 const vpx_prob upd = DIFF_UPDATE_PROB;
185 vpx_prob newp = get_binary_prob(ct[0], ct[1]);
186 const int64_t savings =
187 vp9_prob_diff_update_savings_search(ct, *oldp, &newp, upd);
188 assert(newp >= 1);
189 if (savings > 0) {
190 vpx_write(w, 1, upd);
191 vp9_write_prob_diff_update(w, newp, *oldp);
192 *oldp = newp;
193 } else {
194 vpx_write(w, 0, upd);
195 }
196 }
197