1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libvpx/vp9/encoder/vp9_subexp.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,237 @@
1.4 +/*
1.5 + * Copyright (c) 2013 The WebM project authors. All Rights Reserved.
1.6 + *
1.7 + * Use of this source code is governed by a BSD-style license
1.8 + * that can be found in the LICENSE file in the root of the source
1.9 + * tree. An additional intellectual property rights grant can be found
1.10 + * in the file PATENTS. All contributing project authors may
1.11 + * be found in the AUTHORS file in the root of the source tree.
1.12 + */
1.13 +
1.14 +#include "vp9/common/vp9_common.h"
1.15 +#include "vp9/common/vp9_entropy.h"
1.16 +
1.17 +#include "vp9/encoder/vp9_boolhuff.h"
1.18 +#include "vp9/encoder/vp9_treewriter.h"
1.19 +
1.20 +#define vp9_cost_upd ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)) >> 8)
1.21 +#define vp9_cost_upd256 ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)))
1.22 +
1.23 +static int update_bits[255];
1.24 +
1.25 +static int count_uniform(int v, int n) {
1.26 + int l = get_unsigned_bits(n);
1.27 + int m;
1.28 + if (l == 0) return 0;
1.29 + m = (1 << l) - n;
1.30 + if (v < m)
1.31 + return l - 1;
1.32 + else
1.33 + return l;
1.34 +}
1.35 +
1.36 +static int split_index(int i, int n, int modulus) {
1.37 + int max1 = (n - 1 - modulus / 2) / modulus + 1;
1.38 + if (i % modulus == modulus / 2)
1.39 + i = i / modulus;
1.40 + else
1.41 + i = max1 + i - (i + modulus - modulus / 2) / modulus;
1.42 + return i;
1.43 +}
1.44 +
1.45 +static int recenter_nonneg(int v, int m) {
1.46 + if (v > (m << 1))
1.47 + return v;
1.48 + else if (v >= m)
1.49 + return ((v - m) << 1);
1.50 + else
1.51 + return ((m - v) << 1) - 1;
1.52 +}
1.53 +
1.54 +static int remap_prob(int v, int m) {
1.55 + int i;
1.56 + static const int map_table[MAX_PROB - 1] = {
1.57 + // generated by:
1.58 + // map_table[j] = split_index(j, MAX_PROB - 1, MODULUS_PARAM);
1.59 + 20, 21, 22, 23, 24, 25, 0, 26, 27, 28, 29, 30, 31, 32, 33,
1.60 + 34, 35, 36, 37, 1, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
1.61 + 48, 49, 2, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
1.62 + 3, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 4, 74,
1.63 + 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 5, 86, 87, 88,
1.64 + 89, 90, 91, 92, 93, 94, 95, 96, 97, 6, 98, 99, 100, 101, 102,
1.65 + 103, 104, 105, 106, 107, 108, 109, 7, 110, 111, 112, 113, 114, 115, 116,
1.66 + 117, 118, 119, 120, 121, 8, 122, 123, 124, 125, 126, 127, 128, 129, 130,
1.67 + 131, 132, 133, 9, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144,
1.68 + 145, 10, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 11,
1.69 + 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 12, 170, 171,
1.70 + 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 13, 182, 183, 184, 185,
1.71 + 186, 187, 188, 189, 190, 191, 192, 193, 14, 194, 195, 196, 197, 198, 199,
1.72 + 200, 201, 202, 203, 204, 205, 15, 206, 207, 208, 209, 210, 211, 212, 213,
1.73 + 214, 215, 216, 217, 16, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227,
1.74 + 228, 229, 17, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241,
1.75 + 18, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 19,
1.76 + };
1.77 + v--;
1.78 + m--;
1.79 + if ((m << 1) <= MAX_PROB)
1.80 + i = recenter_nonneg(v, m) - 1;
1.81 + else
1.82 + i = recenter_nonneg(MAX_PROB - 1 - v, MAX_PROB - 1 - m) - 1;
1.83 +
1.84 + i = map_table[i];
1.85 + return i;
1.86 +}
1.87 +
1.88 +static int count_term_subexp(int word, int k, int num_syms) {
1.89 + int count = 0;
1.90 + int i = 0;
1.91 + int mk = 0;
1.92 + while (1) {
1.93 + int b = (i ? k + i - 1 : k);
1.94 + int a = (1 << b);
1.95 + if (num_syms <= mk + 3 * a) {
1.96 + count += count_uniform(word - mk, num_syms - mk);
1.97 + break;
1.98 + } else {
1.99 + int t = (word >= mk + a);
1.100 + count++;
1.101 + if (t) {
1.102 + i = i + 1;
1.103 + mk += a;
1.104 + } else {
1.105 + count += b;
1.106 + break;
1.107 + }
1.108 + }
1.109 + }
1.110 + return count;
1.111 +}
1.112 +
1.113 +static int prob_diff_update_cost(vp9_prob newp, vp9_prob oldp) {
1.114 + int delp = remap_prob(newp, oldp);
1.115 + return update_bits[delp] * 256;
1.116 +}
1.117 +
1.118 +static void encode_uniform(vp9_writer *w, int v, int n) {
1.119 + int l = get_unsigned_bits(n);
1.120 + int m;
1.121 + if (l == 0)
1.122 + return;
1.123 + m = (1 << l) - n;
1.124 + if (v < m) {
1.125 + vp9_write_literal(w, v, l - 1);
1.126 + } else {
1.127 + vp9_write_literal(w, m + ((v - m) >> 1), l - 1);
1.128 + vp9_write_literal(w, (v - m) & 1, 1);
1.129 + }
1.130 +}
1.131 +
1.132 +static void encode_term_subexp(vp9_writer *w, int word, int k, int num_syms) {
1.133 + int i = 0;
1.134 + int mk = 0;
1.135 + while (1) {
1.136 + int b = (i ? k + i - 1 : k);
1.137 + int a = (1 << b);
1.138 + if (num_syms <= mk + 3 * a) {
1.139 + encode_uniform(w, word - mk, num_syms - mk);
1.140 + break;
1.141 + } else {
1.142 + int t = (word >= mk + a);
1.143 + vp9_write_literal(w, t, 1);
1.144 + if (t) {
1.145 + i = i + 1;
1.146 + mk += a;
1.147 + } else {
1.148 + vp9_write_literal(w, word - mk, b);
1.149 + break;
1.150 + }
1.151 + }
1.152 + }
1.153 +}
1.154 +
1.155 +void vp9_write_prob_diff_update(vp9_writer *w, vp9_prob newp, vp9_prob oldp) {
1.156 + const int delp = remap_prob(newp, oldp);
1.157 + encode_term_subexp(w, delp, SUBEXP_PARAM, 255);
1.158 +}
1.159 +
1.160 +void vp9_compute_update_table() {
1.161 + int i;
1.162 + for (i = 0; i < 254; i++)
1.163 + update_bits[i] = count_term_subexp(i, SUBEXP_PARAM, 255);
1.164 +}
1.165 +
1.166 +int vp9_prob_diff_update_savings_search(const unsigned int *ct,
1.167 + vp9_prob oldp, vp9_prob *bestp,
1.168 + vp9_prob upd) {
1.169 + const int old_b = cost_branch256(ct, oldp);
1.170 + int bestsavings = 0;
1.171 + vp9_prob newp, bestnewp = oldp;
1.172 + const int step = *bestp > oldp ? -1 : 1;
1.173 +
1.174 + for (newp = *bestp; newp != oldp; newp += step) {
1.175 + const int new_b = cost_branch256(ct, newp);
1.176 + const int update_b = prob_diff_update_cost(newp, oldp) + vp9_cost_upd256;
1.177 + const int savings = old_b - new_b - update_b;
1.178 + if (savings > bestsavings) {
1.179 + bestsavings = savings;
1.180 + bestnewp = newp;
1.181 + }
1.182 + }
1.183 + *bestp = bestnewp;
1.184 + return bestsavings;
1.185 +}
1.186 +
1.187 +int vp9_prob_diff_update_savings_search_model(const unsigned int *ct,
1.188 + const vp9_prob *oldp,
1.189 + vp9_prob *bestp,
1.190 + vp9_prob upd,
1.191 + int b, int r) {
1.192 + int i, old_b, new_b, update_b, savings, bestsavings, step;
1.193 + int newp;
1.194 + vp9_prob bestnewp, newplist[ENTROPY_NODES], oldplist[ENTROPY_NODES];
1.195 + vp9_model_to_full_probs(oldp, oldplist);
1.196 + vpx_memcpy(newplist, oldp, sizeof(vp9_prob) * UNCONSTRAINED_NODES);
1.197 + for (i = UNCONSTRAINED_NODES, old_b = 0; i < ENTROPY_NODES; ++i)
1.198 + old_b += cost_branch256(ct + 2 * i, oldplist[i]);
1.199 + old_b += cost_branch256(ct + 2 * PIVOT_NODE, oldplist[PIVOT_NODE]);
1.200 +
1.201 + bestsavings = 0;
1.202 + bestnewp = oldp[PIVOT_NODE];
1.203 +
1.204 + step = (*bestp > oldp[PIVOT_NODE] ? -1 : 1);
1.205 +
1.206 + for (newp = *bestp; newp != oldp[PIVOT_NODE]; newp += step) {
1.207 + if (newp < 1 || newp > 255)
1.208 + continue;
1.209 + newplist[PIVOT_NODE] = newp;
1.210 + vp9_model_to_full_probs(newplist, newplist);
1.211 + for (i = UNCONSTRAINED_NODES, new_b = 0; i < ENTROPY_NODES; ++i)
1.212 + new_b += cost_branch256(ct + 2 * i, newplist[i]);
1.213 + new_b += cost_branch256(ct + 2 * PIVOT_NODE, newplist[PIVOT_NODE]);
1.214 + update_b = prob_diff_update_cost(newp, oldp[PIVOT_NODE]) +
1.215 + vp9_cost_upd256;
1.216 + savings = old_b - new_b - update_b;
1.217 + if (savings > bestsavings) {
1.218 + bestsavings = savings;
1.219 + bestnewp = newp;
1.220 + }
1.221 + }
1.222 + *bestp = bestnewp;
1.223 + return bestsavings;
1.224 +}
1.225 +
1.226 +void vp9_cond_prob_diff_update(vp9_writer *w, vp9_prob *oldp,
1.227 + const unsigned int ct[2]) {
1.228 + const vp9_prob upd = DIFF_UPDATE_PROB;
1.229 + vp9_prob newp = get_binary_prob(ct[0], ct[1]);
1.230 + const int savings = vp9_prob_diff_update_savings_search(ct, *oldp, &newp,
1.231 + upd);
1.232 + assert(newp >= 1);
1.233 + if (savings > 0) {
1.234 + vp9_write(w, 1, upd);
1.235 + vp9_write_prob_diff_update(w, newp, *oldp);
1.236 + *oldp = newp;
1.237 + } else {
1.238 + vp9_write(w, 0, upd);
1.239 + }
1.240 +}
