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095c88e4708c3ddb059018fe73b72dbaa36b33d5
vpx/vp10/encoder/subexp.c
Debargha Mukherjee e4bf50b9b9 Make the backward updates work with bitshifts 
Removes integer divides from backward updates for VP10.
Currently this is put in as part of the entropy experiment.
Coding efficiency change is in the noise level.

Change-Id: I5b3c0ab6169ee6d82d0ca1778e264fd4577cdd32
2016-04-28 11:51:18 -07:00

289 lines
10 KiB
C
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/*
* Copyright (c) 2013 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "vp10/encoder/bitwriter.h"
#include "vp10/common/common.h"
#include "vp10/common/entropy.h"
#include "vp10/encoder/cost.h"
#include "vp10/encoder/subexp.h"
#define vp10_cost_upd256 ((int)(vp10_cost_one(upd) - vp10_cost_zero(upd)))
static const uint8_t update_bits[255] = {
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 0,
};
static int recenter_nonneg(int v, int m) {
if (v > (m << 1))
return v;
else if (v >= m)
return ((v - m) << 1);
else
return ((m - v) << 1) - 1;
}
static int remap_prob(int v, int m) {
int i;
static const uint8_t map_table[MAX_PROB - 1] = {
// generated by:
// map_table[j] = split_index(j, MAX_PROB - 1, MODULUS_PARAM);
20, 21, 22, 23, 24, 25, 0, 26, 27, 28, 29, 30, 31, 32, 33,
34, 35, 36, 37, 1, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
48, 49, 2, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
3, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 4, 74,
75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 5, 86, 87, 88,
89, 90, 91, 92, 93, 94, 95, 96, 97, 6, 98, 99, 100, 101, 102,
103, 104, 105, 106, 107, 108, 109, 7, 110, 111, 112, 113, 114, 115, 116,
117, 118, 119, 120, 121, 8, 122, 123, 124, 125, 126, 127, 128, 129, 130,
131, 132, 133, 9, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144,
145, 10, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 11,
158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 12, 170, 171,
172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 13, 182, 183, 184, 185,
186, 187, 188, 189, 190, 191, 192, 193, 14, 194, 195, 196, 197, 198, 199,
200, 201, 202, 203, 204, 205, 15, 206, 207, 208, 209, 210, 211, 212, 213,
214, 215, 216, 217, 16, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227,
228, 229, 17, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241,
18, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 19,
};
v--;
m--;
if ((m << 1) <= MAX_PROB)
i = recenter_nonneg(v, m) - 1;
else
i = recenter_nonneg(MAX_PROB - 1 - v, MAX_PROB - 1 - m) - 1;
i = map_table[i];
return i;
}
static int prob_diff_update_cost(vpx_prob newp, vpx_prob oldp) {
int delp = remap_prob(newp, oldp);
return update_bits[delp] << VP9_PROB_COST_SHIFT;
}
static void encode_uniform(vp10_writer *w, int v) {
const int l = 8;
const int m = (1 << l) - 190;
if (v < m) {
vp10_write_literal(w, v, l - 1);
} else {
vp10_write_literal(w, m + ((v - m) >> 1), l - 1);
vp10_write_literal(w, (v - m) & 1, 1);
}
}
static INLINE int write_bit_gte(vp10_writer *w, int word, int test) {
vp10_write_literal(w, word >= test, 1);
return word >= test;
}
static void encode_term_subexp(vp10_writer *w, int word) {
if (!write_bit_gte(w, word, 16)) {
vp10_write_literal(w, word, 4);
} else if (!write_bit_gte(w, word, 32)) {
vp10_write_literal(w, word - 16, 4);
} else if (!write_bit_gte(w, word, 64)) {
vp10_write_literal(w, word - 32, 5);
} else {
encode_uniform(w, word - 64);
}
}
void vp10_write_prob_diff_update(vp10_writer *w, vpx_prob newp, vpx_prob oldp) {
const int delp = remap_prob(newp, oldp);
encode_term_subexp(w, delp);
}
int vp10_prob_diff_update_savings_search(const unsigned int *ct,
vpx_prob oldp, vpx_prob *bestp,
vpx_prob upd) {
const int old_b = cost_branch256(ct, oldp);
int bestsavings = 0;
vpx_prob newp, bestnewp = oldp;
const int step = *bestp > oldp ? -1 : 1;
for (newp = *bestp; newp != oldp; newp += step) {
const int new_b = cost_branch256(ct, newp);
const int update_b = prob_diff_update_cost(newp, oldp) + vp10_cost_upd256;
const int savings = old_b - new_b - update_b;
if (savings > bestsavings) {
bestsavings = savings;
bestnewp = newp;
}
}
*bestp = bestnewp;
return bestsavings;
}
int vp10_prob_diff_update_savings_search_model(const unsigned int *ct,
const vpx_prob *oldp,
vpx_prob *bestp,
vpx_prob upd,
int stepsize) {
int i, old_b, new_b, update_b, savings, bestsavings;
int newp;
const int step_sign = *bestp > oldp[PIVOT_NODE] ? -1 : 1;
const int step = stepsize * step_sign;
vpx_prob bestnewp, newplist[ENTROPY_NODES], oldplist[ENTROPY_NODES];
vp10_model_to_full_probs(oldp, oldplist);
memcpy(newplist, oldp, sizeof(vpx_prob) * UNCONSTRAINED_NODES);
for (i = UNCONSTRAINED_NODES, old_b = 0; i < ENTROPY_NODES; ++i)
old_b += cost_branch256(ct + 2 * i, oldplist[i]);
old_b += cost_branch256(ct + 2 * PIVOT_NODE, oldplist[PIVOT_NODE]);
bestsavings = 0;
bestnewp = oldp[PIVOT_NODE];
assert(stepsize > 0);
for (newp = *bestp; (newp - oldp[PIVOT_NODE]) * step_sign < 0;
newp += step) {
if (newp < 1 || newp > 255)
continue;
newplist[PIVOT_NODE] = newp;
vp10_model_to_full_probs(newplist, newplist);
for (i = UNCONSTRAINED_NODES, new_b = 0; i < ENTROPY_NODES; ++i)
new_b += cost_branch256(ct + 2 * i, newplist[i]);
new_b += cost_branch256(ct + 2 * PIVOT_NODE, newplist[PIVOT_NODE]);
update_b = prob_diff_update_cost(newp, oldp[PIVOT_NODE]) +
vp10_cost_upd256;
savings = old_b - new_b - update_b;
if (savings > bestsavings) {
bestsavings = savings;
bestnewp = newp;
}
}
*bestp = bestnewp;
return bestsavings;
}
#if CONFIG_ENTROPY
static int get_cost(unsigned int ct[][2], vpx_prob p, int n) {
int i, p0 = p;
unsigned int total_ct[2] = {0 , 0};
int cost = 0;
for (i = 0; i <= n; ++i) {
cost += cost_branch256(ct[i], p);
total_ct[0] += ct[i][0];
total_ct[1] += ct[i][1];
if (i < n)
p = vp10_merge_probs(p0, total_ct,
COEF_COUNT_SAT_BITS, COEF_MAX_UPDATE_FACTOR_BITS);
}
return cost;
}
int vp10_prob_update_search_subframe(unsigned int ct[][2],
vpx_prob oldp, vpx_prob *bestp,
vpx_prob upd, int n) {
const int old_b = get_cost(ct, oldp, n);
int bestsavings = 0;
vpx_prob newp, bestnewp = oldp;
const int step = *bestp > oldp ? -1 : 1;
for (newp = *bestp; newp != oldp; newp += step) {
const int new_b = get_cost(ct, newp, n);
const int update_b = prob_diff_update_cost(newp, oldp) + vp10_cost_upd256;
const int savings = old_b - new_b - update_b;
if (savings > bestsavings) {
bestsavings = savings;
bestnewp = newp;
}
}
*bestp = bestnewp;
return bestsavings;
}
int vp10_prob_update_search_model_subframe(unsigned int ct[ENTROPY_NODES]
[COEF_PROBS_BUFS][2],
const vpx_prob *oldp,
vpx_prob *bestp, vpx_prob upd,
int stepsize, int n) {
int i, old_b, new_b, update_b, savings, bestsavings;
int newp;
const int step_sign = *bestp > oldp[PIVOT_NODE] ? -1 : 1;
const int step = stepsize * step_sign;
vpx_prob bestnewp, newplist[ENTROPY_NODES], oldplist[ENTROPY_NODES];
vp10_model_to_full_probs(oldp, oldplist);
memcpy(newplist, oldp, sizeof(vpx_prob) * UNCONSTRAINED_NODES);
for (i = UNCONSTRAINED_NODES, old_b = 0; i < ENTROPY_NODES; ++i)
old_b += get_cost(ct[i], oldplist[i], n);
old_b += get_cost(ct[PIVOT_NODE], oldplist[PIVOT_NODE], n);
bestsavings = 0;
bestnewp = oldp[PIVOT_NODE];
assert(stepsize > 0);
for (newp = *bestp; (newp - oldp[PIVOT_NODE]) * step_sign < 0;
newp += step) {
if (newp < 1 || newp > 255)
continue;
newplist[PIVOT_NODE] = newp;
vp10_model_to_full_probs(newplist, newplist);
for (i = UNCONSTRAINED_NODES, new_b = 0; i < ENTROPY_NODES; ++i)
new_b += get_cost(ct[i], newplist[i], n);
new_b += get_cost(ct[PIVOT_NODE], newplist[PIVOT_NODE], n);
update_b = prob_diff_update_cost(newp, oldp[PIVOT_NODE]) +
vp10_cost_upd256;
savings = old_b - new_b - update_b;
if (savings > bestsavings) {
bestsavings = savings;
bestnewp = newp;
}
}
*bestp = bestnewp;
return bestsavings;
}
#endif // CONFIG_ENTROPY
void vp10_cond_prob_diff_update(vp10_writer *w, vpx_prob *oldp,
const unsigned int ct[2]) {
const vpx_prob upd = DIFF_UPDATE_PROB;
vpx_prob newp = get_binary_prob(ct[0], ct[1]);
const int savings = vp10_prob_diff_update_savings_search(ct, *oldp, &newp,
upd);
assert(newp >= 1);
if (savings > 0) {
vp10_write(w, 1, upd);
vp10_write_prob_diff_update(w, newp, *oldp);
*oldp = newp;
} else {
vp10_write(w, 0, upd);
}
}
int vp10_cond_prob_diff_update_savings(vpx_prob *oldp,
const unsigned int ct[2]) {
const vpx_prob upd = DIFF_UPDATE_PROB;
vpx_prob newp = get_binary_prob(ct[0], ct[1]);
const int savings = vp10_prob_diff_update_savings_search(ct, *oldp, &newp,
upd);
return savings;
}
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