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media/libvpx/vp9/encoder/vp9_subexp.c@b8a032363ba2 (annotated)

media/libvpx/vp9/encoder/vp9_subexp.c

Thu, 22 Jan 2015 13:21:57 +0100

author

Michael Schloh von Bennewitz <michael@schloh.com>

date

Thu, 22 Jan 2015 13:21:57 +0100

branch

TOR_BUG_9701

changeset 15

b8a032363ba2

permissions

-rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

michael@0	1	/*
michael@0	2	* Copyright (c) 2013 The WebM project authors. All Rights Reserved.
michael@0	3	*
michael@0	4	* Use of this source code is governed by a BSD-style license
michael@0	5	* that can be found in the LICENSE file in the root of the source
michael@0	6	* tree. An additional intellectual property rights grant can be found
michael@0	7	* in the file PATENTS. All contributing project authors may
michael@0	8	* be found in the AUTHORS file in the root of the source tree.
michael@0	9	*/
michael@0	10
michael@0	11	#include "vp9/common/vp9_common.h"
michael@0	12	#include "vp9/common/vp9_entropy.h"
michael@0	13
michael@0	14	#include "vp9/encoder/vp9_boolhuff.h"
michael@0	15	#include "vp9/encoder/vp9_treewriter.h"
michael@0	16
michael@0	17	#define vp9_cost_upd ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)) >> 8)
michael@0	18	#define vp9_cost_upd256 ((int)(vp9_cost_one(upd) - vp9_cost_zero(upd)))
michael@0	19
michael@0	20	static int update_bits[255];
michael@0	21
michael@0	22	static int count_uniform(int v, int n) {
michael@0	23	int l = get_unsigned_bits(n);
michael@0	24	int m;
michael@0	25	if (l == 0) return 0;
michael@0	26	m = (1 << l) - n;
michael@0	27	if (v < m)
michael@0	28	return l - 1;
michael@0	29	else
michael@0	30	return l;
michael@0	31	}
michael@0	32
michael@0	33	static int split_index(int i, int n, int modulus) {
michael@0	34	int max1 = (n - 1 - modulus / 2) / modulus + 1;
michael@0	35	if (i % modulus == modulus / 2)
michael@0	36	i = i / modulus;
michael@0	37	else
michael@0	38	i = max1 + i - (i + modulus - modulus / 2) / modulus;
michael@0	39	return i;
michael@0	40	}
michael@0	41
michael@0	42	static int recenter_nonneg(int v, int m) {
michael@0	43	if (v > (m << 1))
michael@0	44	return v;
michael@0	45	else if (v >= m)
michael@0	46	return ((v - m) << 1);
michael@0	47	else
michael@0	48	return ((m - v) << 1) - 1;
michael@0	49	}
michael@0	50
michael@0	51	static int remap_prob(int v, int m) {
michael@0	52	int i;
michael@0	53	static const int map_table[MAX_PROB - 1] = {
michael@0	54	// generated by:
michael@0	55	// map_table[j] = split_index(j, MAX_PROB - 1, MODULUS_PARAM);
michael@0	56	20, 21, 22, 23, 24, 25, 0, 26, 27, 28, 29, 30, 31, 32, 33,
michael@0	57	34, 35, 36, 37, 1, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
michael@0	58	48, 49, 2, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
michael@0	59	3, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 4, 74,
michael@0	60	75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 5, 86, 87, 88,
michael@0	61	89, 90, 91, 92, 93, 94, 95, 96, 97, 6, 98, 99, 100, 101, 102,
michael@0	62	103, 104, 105, 106, 107, 108, 109, 7, 110, 111, 112, 113, 114, 115, 116,
michael@0	63	117, 118, 119, 120, 121, 8, 122, 123, 124, 125, 126, 127, 128, 129, 130,
michael@0	64	131, 132, 133, 9, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144,
michael@0	65	145, 10, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 11,
michael@0	66	158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 12, 170, 171,
michael@0	67	172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 13, 182, 183, 184, 185,
michael@0	68	186, 187, 188, 189, 190, 191, 192, 193, 14, 194, 195, 196, 197, 198, 199,
michael@0	69	200, 201, 202, 203, 204, 205, 15, 206, 207, 208, 209, 210, 211, 212, 213,
michael@0	70	214, 215, 216, 217, 16, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227,
michael@0	71	228, 229, 17, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241,
michael@0	72	18, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 19,
michael@0	73	};
michael@0	74	v--;
michael@0	75	m--;
michael@0	76	if ((m << 1) <= MAX_PROB)
michael@0	77	i = recenter_nonneg(v, m) - 1;
michael@0	78	else
michael@0	79	i = recenter_nonneg(MAX_PROB - 1 - v, MAX_PROB - 1 - m) - 1;
michael@0	80
michael@0	81	i = map_table[i];
michael@0	82	return i;
michael@0	83	}
michael@0	84
michael@0	85	static int count_term_subexp(int word, int k, int num_syms) {
michael@0	86	int count = 0;
michael@0	87	int i = 0;
michael@0	88	int mk = 0;
michael@0	89	while (1) {
michael@0	90	int b = (i ? k + i - 1 : k);
michael@0	91	int a = (1 << b);
michael@0	92	if (num_syms <= mk + 3 * a) {
michael@0	93	count += count_uniform(word - mk, num_syms - mk);
michael@0	94	break;
michael@0	95	} else {
michael@0	96	int t = (word >= mk + a);
michael@0	97	count++;
michael@0	98	if (t) {
michael@0	99	i = i + 1;
michael@0	100	mk += a;
michael@0	101	} else {
michael@0	102	count += b;
michael@0	103	break;
michael@0	104	}
michael@0	105	}
michael@0	106	}
michael@0	107	return count;
michael@0	108	}
michael@0	109
michael@0	110	static int prob_diff_update_cost(vp9_prob newp, vp9_prob oldp) {
michael@0	111	int delp = remap_prob(newp, oldp);
michael@0	112	return update_bits[delp] * 256;
michael@0	113	}
michael@0	114
michael@0	115	static void encode_uniform(vp9_writer *w, int v, int n) {
michael@0	116	int l = get_unsigned_bits(n);
michael@0	117	int m;
michael@0	118	if (l == 0)
michael@0	119	return;
michael@0	120	m = (1 << l) - n;
michael@0	121	if (v < m) {
michael@0	122	vp9_write_literal(w, v, l - 1);
michael@0	123	} else {
michael@0	124	vp9_write_literal(w, m + ((v - m) >> 1), l - 1);
michael@0	125	vp9_write_literal(w, (v - m) & 1, 1);
michael@0	126	}
michael@0	127	}
michael@0	128
michael@0	129	static void encode_term_subexp(vp9_writer *w, int word, int k, int num_syms) {
michael@0	130	int i = 0;
michael@0	131	int mk = 0;
michael@0	132	while (1) {
michael@0	133	int b = (i ? k + i - 1 : k);
michael@0	134	int a = (1 << b);
michael@0	135	if (num_syms <= mk + 3 * a) {
michael@0	136	encode_uniform(w, word - mk, num_syms - mk);
michael@0	137	break;
michael@0	138	} else {
michael@0	139	int t = (word >= mk + a);
michael@0	140	vp9_write_literal(w, t, 1);
michael@0	141	if (t) {
michael@0	142	i = i + 1;
michael@0	143	mk += a;
michael@0	144	} else {
michael@0	145	vp9_write_literal(w, word - mk, b);
michael@0	146	break;
michael@0	147	}
michael@0	148	}
michael@0	149	}
michael@0	150	}
michael@0	151
michael@0	152	void vp9_write_prob_diff_update(vp9_writer *w, vp9_prob newp, vp9_prob oldp) {
michael@0	153	const int delp = remap_prob(newp, oldp);
michael@0	154	encode_term_subexp(w, delp, SUBEXP_PARAM, 255);
michael@0	155	}
michael@0	156
michael@0	157	void vp9_compute_update_table() {
michael@0	158	int i;
michael@0	159	for (i = 0; i < 254; i++)
michael@0	160	update_bits[i] = count_term_subexp(i, SUBEXP_PARAM, 255);
michael@0	161	}
michael@0	162
michael@0	163	int vp9_prob_diff_update_savings_search(const unsigned int *ct,
michael@0	164	vp9_prob oldp, vp9_prob *bestp,
michael@0	165	vp9_prob upd) {
michael@0	166	const int old_b = cost_branch256(ct, oldp);
michael@0	167	int bestsavings = 0;
michael@0	168	vp9_prob newp, bestnewp = oldp;
michael@0	169	const int step = *bestp > oldp ? -1 : 1;
michael@0	170
michael@0	171	for (newp = *bestp; newp != oldp; newp += step) {
michael@0	172	const int new_b = cost_branch256(ct, newp);
michael@0	173	const int update_b = prob_diff_update_cost(newp, oldp) + vp9_cost_upd256;
michael@0	174	const int savings = old_b - new_b - update_b;
michael@0	175	if (savings > bestsavings) {
michael@0	176	bestsavings = savings;
michael@0	177	bestnewp = newp;
michael@0	178	}
michael@0	179	}
michael@0	180	*bestp = bestnewp;
michael@0	181	return bestsavings;
michael@0	182	}
michael@0	183
michael@0	184	int vp9_prob_diff_update_savings_search_model(const unsigned int *ct,
michael@0	185	const vp9_prob *oldp,
michael@0	186	vp9_prob *bestp,
michael@0	187	vp9_prob upd,
michael@0	188	int b, int r) {
michael@0	189	int i, old_b, new_b, update_b, savings, bestsavings, step;
michael@0	190	int newp;
michael@0	191	vp9_prob bestnewp, newplist[ENTROPY_NODES], oldplist[ENTROPY_NODES];
michael@0	192	vp9_model_to_full_probs(oldp, oldplist);
michael@0	193	vpx_memcpy(newplist, oldp, sizeof(vp9_prob) * UNCONSTRAINED_NODES);
michael@0	194	for (i = UNCONSTRAINED_NODES, old_b = 0; i < ENTROPY_NODES; ++i)
michael@0	195	old_b += cost_branch256(ct + 2 * i, oldplist[i]);
michael@0	196	old_b += cost_branch256(ct + 2 * PIVOT_NODE, oldplist[PIVOT_NODE]);
michael@0	197
michael@0	198	bestsavings = 0;
michael@0	199	bestnewp = oldp[PIVOT_NODE];
michael@0	200
michael@0	201	step = (*bestp > oldp[PIVOT_NODE] ? -1 : 1);
michael@0	202
michael@0	203	for (newp = *bestp; newp != oldp[PIVOT_NODE]; newp += step) {
michael@0	204	if (newp < 1 || newp > 255)
michael@0	205	continue;
michael@0	206	newplist[PIVOT_NODE] = newp;
michael@0	207	vp9_model_to_full_probs(newplist, newplist);
michael@0	208	for (i = UNCONSTRAINED_NODES, new_b = 0; i < ENTROPY_NODES; ++i)
michael@0	209	new_b += cost_branch256(ct + 2 * i, newplist[i]);
michael@0	210	new_b += cost_branch256(ct + 2 * PIVOT_NODE, newplist[PIVOT_NODE]);
michael@0	211	update_b = prob_diff_update_cost(newp, oldp[PIVOT_NODE]) +
michael@0	212	vp9_cost_upd256;
michael@0	213	savings = old_b - new_b - update_b;
michael@0	214	if (savings > bestsavings) {
michael@0	215	bestsavings = savings;
michael@0	216	bestnewp = newp;
michael@0	217	}
michael@0	218	}
michael@0	219	*bestp = bestnewp;
michael@0	220	return bestsavings;
michael@0	221	}
michael@0	222
michael@0	223	void vp9_cond_prob_diff_update(vp9_writer *w, vp9_prob *oldp,
michael@0	224	const unsigned int ct[2]) {
michael@0	225	const vp9_prob upd = DIFF_UPDATE_PROB;
michael@0	226	vp9_prob newp = get_binary_prob(ct[0], ct[1]);
michael@0	227	const int savings = vp9_prob_diff_update_savings_search(ct, *oldp, &newp,
michael@0	228	upd);
michael@0	229	assert(newp >= 1);
michael@0	230	if (savings > 0) {
michael@0	231	vp9_write(w, 1, upd);
michael@0	232	vp9_write_prob_diff_update(w, newp, *oldp);
michael@0	233	*oldp = newp;
michael@0	234	} else {
michael@0	235	vp9_write(w, 0, upd);
michael@0	236	}
michael@0	237	}