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 #include "vp9/common/vp9_common.h" 12 #include "vp9/common/vp9_entropy.h" 13 14 #include "vp9/encoder/vp9_cost.h" 15 #include "vp9/encoder/vp9_writer.h" 16 17 #define vp9_cost_upd256 ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd))) 18 19 static int update_bits[255]; 20 21 static int recenter_nonneg(int v, int m) { 22 if (v > (m << 1)) 23 return v; 24 else if (v >= m) 25 return ((v - m) << 1); 26 else 27 return ((m - v) << 1) - 1; 28 } 29 30 static int remap_prob(int v, int m) { 31 int i; 32 static const int map_table[MAX_PROB - 1] = { 33 // generated by: 34 // map_table[j] = split_index(j, MAX_PROB - 1, MODULUS_PARAM); 35 20, 21, 22, 23, 24, 25, 0, 26, 27, 28, 29, 30, 31, 32, 33, 36 34, 35, 36, 37, 1, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 37 48, 49, 2, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 38 3, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 4, 74, 39 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 5, 86, 87, 88, 40 89, 90, 91, 92, 93, 94, 95, 96, 97, 6, 98, 99, 100, 101, 102, 41 103, 104, 105, 106, 107, 108, 109, 7, 110, 111, 112, 113, 114, 115, 116, 42 117, 118, 119, 120, 121, 8, 122, 123, 124, 125, 126, 127, 128, 129, 130, 43 131, 132, 133, 9, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 44 145, 10, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 11, 45 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 12, 170, 171, 46 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 13, 182, 183, 184, 185, 47 186, 187, 188, 189, 190, 191, 192, 193, 14, 194, 195, 196, 197, 198, 199, 48 200, 201, 202, 203, 204, 205, 15, 206, 207, 208, 209, 210, 211, 212, 213, 49 214, 215, 216, 217, 16, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 50 228, 229, 17, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 51 18, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 19, 52 }; 53 v--; 54 m--; 55 if ((m << 1) <= MAX_PROB) 56 i = recenter_nonneg(v, m) - 1; 57 else 58 i = recenter_nonneg(MAX_PROB - 1 - v, MAX_PROB - 1 - m) - 1; 59 60 i = map_table[i]; 61 return i; 62 } 63 64 static int count_term_subexp(int word) { 65 if (word < 16) 66 return 5; 67 if (word < 32) 68 return 6; 69 if (word < 64) 70 return 8; 71 if (word < 129) 72 return 10; 73 return 11; 74 } 75 76 static int prob_diff_update_cost(vp9_prob newp, vp9_prob oldp) { 77 int delp = remap_prob(newp, oldp); 78 return update_bits[delp] * 256; 79 } 80 81 static void encode_uniform(vp9_writer *w, int v) { 82 const int l = 8; 83 const int m = (1 << l) - 191; 84 if (v < m) { 85 vp9_write_literal(w, v, l - 1); 86 } else { 87 vp9_write_literal(w, m + ((v - m) >> 1), l - 1); 88 vp9_write_literal(w, (v - m) & 1, 1); 89 } 90 } 91 92 static INLINE int write_bit_gte(vp9_writer *w, int word, int test) { 93 vp9_write_literal(w, word >= test, 1); 94 return word >= test; 95 } 96 97 static void encode_term_subexp(vp9_writer *w, int word) { 98 if (!write_bit_gte(w, word, 16)) { 99 vp9_write_literal(w, word, 4); 100 } else if (!write_bit_gte(w, word, 32)) { 101 vp9_write_literal(w, word - 16, 4); 102 } else if (!write_bit_gte(w, word, 64)) { 103 vp9_write_literal(w, word - 32, 5); 104 } else { 105 encode_uniform(w, word - 64); 106 } 107 } 108 109 void vp9_write_prob_diff_update(vp9_writer *w, vp9_prob newp, vp9_prob oldp) { 110 const int delp = remap_prob(newp, oldp); 111 encode_term_subexp(w, delp); 112 } 113 114 void vp9_compute_update_table() { 115 int i; 116 for (i = 0; i < 254; i++) 117 update_bits[i] = count_term_subexp(i); 118 } 119 120 int vp9_prob_diff_update_savings_search(const unsigned int *ct, 121 vp9_prob oldp, vp9_prob *bestp, 122 vp9_prob upd) { 123 const int old_b = cost_branch256(ct, oldp); 124 int bestsavings = 0; 125 vp9_prob newp, bestnewp = oldp; 126 const int step = *bestp > oldp ? -1 : 1; 127 128 for (newp = *bestp; newp != oldp; newp += step) { 129 const int new_b = cost_branch256(ct, newp); 130 const int update_b = prob_diff_update_cost(newp, oldp) + vp9_cost_upd256; 131 const int savings = old_b - new_b - update_b; 132 if (savings > bestsavings) { 133 bestsavings = savings; 134 bestnewp = newp; 135 } 136 } 137 *bestp = bestnewp; 138 return bestsavings; 139 } 140 141 int vp9_prob_diff_update_savings_search_model(const unsigned int *ct, 142 const vp9_prob *oldp, 143 vp9_prob *bestp, 144 vp9_prob upd) { 145 int i, old_b, new_b, update_b, savings, bestsavings, step; 146 int newp; 147 vp9_prob bestnewp, newplist[ENTROPY_NODES], oldplist[ENTROPY_NODES]; 148 vp9_model_to_full_probs(oldp, oldplist); 149 vpx_memcpy(newplist, oldp, sizeof(vp9_prob) * UNCONSTRAINED_NODES); 150 for (i = UNCONSTRAINED_NODES, old_b = 0; i < ENTROPY_NODES; ++i) 151 old_b += cost_branch256(ct + 2 * i, oldplist[i]); 152 old_b += cost_branch256(ct + 2 * PIVOT_NODE, oldplist[PIVOT_NODE]); 153 154 bestsavings = 0; 155 bestnewp = oldp[PIVOT_NODE]; 156 157 step = (*bestp > oldp[PIVOT_NODE] ? -1 : 1); 158 159 for (newp = *bestp; newp != oldp[PIVOT_NODE]; newp += step) { 160 if (newp < 1 || newp > 255) 161 continue; 162 newplist[PIVOT_NODE] = newp; 163 vp9_model_to_full_probs(newplist, newplist); 164 for (i = UNCONSTRAINED_NODES, new_b = 0; i < ENTROPY_NODES; ++i) 165 new_b += cost_branch256(ct + 2 * i, newplist[i]); 166 new_b += cost_branch256(ct + 2 * PIVOT_NODE, newplist[PIVOT_NODE]); 167 update_b = prob_diff_update_cost(newp, oldp[PIVOT_NODE]) + 168 vp9_cost_upd256; 169 savings = old_b - new_b - update_b; 170 if (savings > bestsavings) { 171 bestsavings = savings; 172 bestnewp = newp; 173 } 174 } 175 *bestp = bestnewp; 176 return bestsavings; 177 } 178 179 void vp9_cond_prob_diff_update(vp9_writer *w, vp9_prob *oldp, 180 const unsigned int ct[2]) { 181 const vp9_prob upd = DIFF_UPDATE_PROB; 182 vp9_prob newp = get_binary_prob(ct[0], ct[1]); 183 const int savings = vp9_prob_diff_update_savings_search(ct, *oldp, &newp, 184 upd); 185 assert(newp >= 1); 186 if (savings > 0) { 187 vp9_write(w, 1, upd); 188 vp9_write_prob_diff_update(w, newp, *oldp); 189 *oldp = newp; 190 } else { 191 vp9_write(w, 0, upd); 192 } 193 } 194
