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 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 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 i = map_table[i]; 75 return i; 76 } 77 78 static int prob_diff_update_cost(vpx_prob newp, vpx_prob oldp) { 79 int delp = remap_prob(newp, oldp); 80 return update_bits[delp] << VP9_PROB_COST_SHIFT; 81 } 82 83 static void encode_uniform(vpx_writer *w, int v) { 84 const int l = 8; 85 const int m = (1 << l) - 191; 86 if (v < m) { 87 vpx_write_literal(w, v, l - 1); 88 } else { 89 vpx_write_literal(w, m + ((v - m) >> 1), l - 1); 90 vpx_write_literal(w, (v - m) & 1, 1); 91 } 92 } 93 94 static INLINE int write_bit_gte(vpx_writer *w, int word, int test) { 95 vpx_write_literal(w, word >= test, 1); 96 return word >= test; 97 } 98 99 static void encode_term_subexp(vpx_writer *w, int word) { 100 if (!write_bit_gte(w, word, 16)) { 101 vpx_write_literal(w, word, 4); 102 } else if (!write_bit_gte(w, word, 32)) { 103 vpx_write_literal(w, word - 16, 4); 104 } else if (!write_bit_gte(w, word, 64)) { 105 vpx_write_literal(w, word - 32, 5); 106 } else { 107 encode_uniform(w, word - 64); 108 } 109 } 110 111 void vp9_write_prob_diff_update(vpx_writer *w, vpx_prob newp, vpx_prob oldp) { 112 const int delp = remap_prob(newp, oldp); 113 encode_term_subexp(w, delp); 114 } 115 116 int vp9_prob_diff_update_savings_search(const unsigned int *ct, vpx_prob oldp, 117 vpx_prob *bestp, vpx_prob upd) { 118 const int old_b = cost_branch256(ct, oldp); 119 int bestsavings = 0; 120 vpx_prob newp, bestnewp = oldp; 121 const int step = *bestp > oldp ? -1 : 1; 122 const int upd_cost = vp9_cost_one(upd) - vp9_cost_zero(upd); 123 124 if (old_b > upd_cost + (MIN_DELP_BITS << VP9_PROB_COST_SHIFT)) { 125 for (newp = *bestp; newp != oldp; newp += step) { 126 const int new_b = cost_branch256(ct, newp); 127 const int update_b = prob_diff_update_cost(newp, oldp) + upd_cost; 128 const int savings = old_b - new_b - update_b; 129 if (savings > bestsavings) { 130 bestsavings = savings; 131 bestnewp = newp; 132 } 133 } 134 } 135 *bestp = bestnewp; 136 return bestsavings; 137 } 138 139 int vp9_prob_diff_update_savings_search_model(const unsigned int *ct, 140 const vpx_prob oldp, 141 vpx_prob *bestp, vpx_prob upd, 142 int stepsize) { 143 int i, old_b, new_b, update_b, savings, bestsavings; 144 int newp; 145 const int step_sign = *bestp > oldp ? -1 : 1; 146 const int step = stepsize * step_sign; 147 const int upd_cost = vp9_cost_one(upd) - vp9_cost_zero(upd); 148 const vpx_prob *newplist, *oldplist; 149 vpx_prob bestnewp; 150 oldplist = vp9_pareto8_full[oldp - 1]; 151 old_b = cost_branch256(ct + 2 * PIVOT_NODE, oldp); 152 for (i = UNCONSTRAINED_NODES; i < ENTROPY_NODES; ++i) 153 old_b += cost_branch256(ct + 2 * i, oldplist[i - UNCONSTRAINED_NODES]); 154 155 bestsavings = 0; 156 bestnewp = oldp; 157 158 assert(stepsize > 0); 159 160 if (old_b > upd_cost + (MIN_DELP_BITS << VP9_PROB_COST_SHIFT)) { 161 for (newp = *bestp; (newp - oldp) * step_sign < 0; newp += step) { 162 if (newp < 1 || newp > 255) continue; 163 newplist = vp9_pareto8_full[newp - 1]; 164 new_b = cost_branch256(ct + 2 * PIVOT_NODE, newp); 165 for (i = UNCONSTRAINED_NODES; i < ENTROPY_NODES; ++i) 166 new_b += cost_branch256(ct + 2 * i, newplist[i - UNCONSTRAINED_NODES]); 167 update_b = prob_diff_update_cost(newp, oldp) + upd_cost; 168 savings = old_b - new_b - update_b; 169 if (savings > bestsavings) { 170 bestsavings = savings; 171 bestnewp = newp; 172 } 173 } 174 } 175 176 *bestp = bestnewp; 177 return bestsavings; 178 } 179 180 void vp9_cond_prob_diff_update(vpx_writer *w, vpx_prob *oldp, 181 const unsigned int ct[2]) { 182 const vpx_prob upd = DIFF_UPDATE_PROB; 183 vpx_prob newp = get_binary_prob(ct[0], ct[1]); 184 const int savings = 185 vp9_prob_diff_update_savings_search(ct, *oldp, &newp, upd); 186 assert(newp >= 1); 187 if (savings > 0) { 188 vpx_write(w, 1, upd); 189 vp9_write_prob_diff_update(w, newp, *oldp); 190 *oldp = newp; 191 } else { 192 vpx_write(w, 0, upd); 193 } 194 } 195
