ref: b2120948391f8beb7ff74bd46b83da1ff2020f49
dir: /vp8/encoder/encodemv.c/
/*
* Copyright (c) 2010 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 "vp8/common/common.h"
#include "encodemv.h"
#include "vp8/common/entropymode.h"
#include "vp8/common/systemdependent.h"
#include <math.h>
#ifdef VP8_ENTROPY_STATS
extern unsigned int active_section;
#endif
static void encode_mvcomponent(
vp8_writer *const w,
const int v,
const struct mv_context *mvc
)
{
const vp8_prob *p = mvc->prob;
const int x = v < 0 ? -v : v;
if (x < mvnum_short) /* Small */
{
vp8_write(w, 0, p [mvpis_short]);
vp8_treed_write(w, vp8_small_mvtree, p + MVPshort, x, 3);
if (!x)
return; /* no sign bit */
}
else /* Large */
{
int i = 0;
vp8_write(w, 1, p [mvpis_short]);
do
vp8_write(w, (x >> i) & 1, p [MVPbits + i]);
while (++i < 3);
i = mvlong_width - 1; /* Skip bit 3, which is sometimes implicit */
do
vp8_write(w, (x >> i) & 1, p [MVPbits + i]);
while (--i > 3);
if (x & 0xFFF0)
vp8_write(w, (x >> 3) & 1, p [MVPbits + 3]);
}
vp8_write(w, v < 0, p [MVPsign]);
}
#if 0
static int max_mv_r = 0;
static int max_mv_c = 0;
#endif
void vp8_encode_motion_vector(vp8_writer *w, const MV *mv, const MV_CONTEXT *mvc)
{
#if 0
{
if (abs(mv->row >> 1) > max_mv_r)
{
FILE *f = fopen("maxmv.stt", "a");
max_mv_r = abs(mv->row >> 1);
fprintf(f, "New Mv Row Max %6d\n", (mv->row >> 1));
if ((abs(mv->row) / 2) != max_mv_r)
fprintf(f, "MV Row conversion error %6d\n", abs(mv->row) / 2);
fclose(f);
}
if (abs(mv->col >> 1) > max_mv_c)
{
FILE *f = fopen("maxmv.stt", "a");
fprintf(f, "New Mv Col Max %6d\n", (mv->col >> 1));
max_mv_c = abs(mv->col >> 1);
fclose(f);
}
}
#endif
encode_mvcomponent(w, mv->row >> 1, &mvc[0]);
encode_mvcomponent(w, mv->col >> 1, &mvc[1]);
}
static unsigned int cost_mvcomponent(const int v, const struct mv_context *mvc)
{
const vp8_prob *p = mvc->prob;
const int x = v;
unsigned int cost;
if (x < mvnum_short)
{
cost = vp8_cost_zero(p [mvpis_short])
+ vp8_treed_cost(vp8_small_mvtree, p + MVPshort, x, 3);
if (!x)
return cost;
}
else
{
int i = 0;
cost = vp8_cost_one(p [mvpis_short]);
do
cost += vp8_cost_bit(p [MVPbits + i], (x >> i) & 1);
while (++i < 3);
i = mvlong_width - 1; /* Skip bit 3, which is sometimes implicit */
do
cost += vp8_cost_bit(p [MVPbits + i], (x >> i) & 1);
while (--i > 3);
if (x & 0xFFF0)
cost += vp8_cost_bit(p [MVPbits + 3], (x >> 3) & 1);
}
return cost; /* + vp8_cost_bit( p [MVPsign], v < 0); */
}
void vp8_build_component_cost_table(int *mvcost[2], const MV_CONTEXT *mvc, int mvc_flag[2])
{
int i = 1;
unsigned int cost0 = 0;
unsigned int cost1 = 0;
vp8_clear_system_state();
i = 1;
if (mvc_flag[0])
{
mvcost [0] [0] = cost_mvcomponent(0, &mvc[0]);
do
{
cost0 = cost_mvcomponent(i, &mvc[0]);
mvcost [0] [i] = cost0 + vp8_cost_zero(mvc[0].prob[MVPsign]);
mvcost [0] [-i] = cost0 + vp8_cost_one(mvc[0].prob[MVPsign]);
}
while (++i <= mv_max);
}
i = 1;
if (mvc_flag[1])
{
mvcost [1] [0] = cost_mvcomponent(0, &mvc[1]);
do
{
cost1 = cost_mvcomponent(i, &mvc[1]);
mvcost [1] [i] = cost1 + vp8_cost_zero(mvc[1].prob[MVPsign]);
mvcost [1] [-i] = cost1 + vp8_cost_one(mvc[1].prob[MVPsign]);
}
while (++i <= mv_max);
}
}
/* Motion vector probability table update depends on benefit.
* Small correction allows for the fact that an update to an MV probability
* may have benefit in subsequent frames as well as the current one.
*/
#define MV_PROB_UPDATE_CORRECTION -1
static void calc_prob(vp8_prob *p, const unsigned int ct[2])
{
const unsigned int tot = ct[0] + ct[1];
if (tot)
{
const vp8_prob x = ((ct[0] * 255) / tot) & -2;
*p = x ? x : 1;
}
}
static void update(
vp8_writer *const w,
const unsigned int ct[2],
vp8_prob *const cur_p,
const vp8_prob new_p,
const vp8_prob update_p,
int *updated
)
{
const int cur_b = vp8_cost_branch(ct, *cur_p);
const int new_b = vp8_cost_branch(ct, new_p);
const int cost = 7 + MV_PROB_UPDATE_CORRECTION + ((vp8_cost_one(update_p) - vp8_cost_zero(update_p) + 128) >> 8);
if (cur_b - new_b > cost)
{
*cur_p = new_p;
vp8_write(w, 1, update_p);
vp8_write_literal(w, new_p >> 1, 7);
*updated = 1;
}
else
vp8_write(w, 0, update_p);
}
static void write_component_probs(
vp8_writer *const w,
struct mv_context *cur_mvc,
const struct mv_context *default_mvc_,
const struct mv_context *update_mvc,
const unsigned int events [MVvals],
unsigned int rc,
int *updated
)
{
vp8_prob *Pcur = cur_mvc->prob;
const vp8_prob *default_mvc = default_mvc_->prob;
const vp8_prob *Pupdate = update_mvc->prob;
unsigned int is_short_ct[2], sign_ct[2];
unsigned int bit_ct [mvlong_width] [2];
unsigned int short_ct [mvnum_short];
unsigned int short_bct [mvnum_short-1] [2];
vp8_prob Pnew [MVPcount];
(void) rc;
vp8_copy_array(Pnew, default_mvc, MVPcount);
vp8_zero(is_short_ct)
vp8_zero(sign_ct)
vp8_zero(bit_ct)
vp8_zero(short_ct)
vp8_zero(short_bct)
/* j=0 */
{
const int c = events [mv_max];
is_short_ct [0] += c; /* Short vector */
short_ct [0] += c; /* Magnitude distribution */
}
/* j: 1 ~ mv_max (1023) */
{
int j = 1;
do
{
const int c1 = events [mv_max + j]; /* positive */
const int c2 = events [mv_max - j]; /* negative */
const int c = c1 + c2;
int a = j;
sign_ct [0] += c1;
sign_ct [1] += c2;
if (a < mvnum_short)
{
is_short_ct [0] += c; /* Short vector */
short_ct [a] += c; /* Magnitude distribution */
}
else
{
int k = mvlong_width - 1;
is_short_ct [1] += c; /* Long vector */
/* bit 3 not always encoded. */
do
bit_ct [k] [(a >> k) & 1] += c;
while (--k >= 0);
}
}
while (++j <= mv_max);
}
calc_prob(Pnew + mvpis_short, is_short_ct);
calc_prob(Pnew + MVPsign, sign_ct);
{
vp8_prob p [mvnum_short - 1]; /* actually only need branch ct */
int j = 0;
vp8_tree_probs_from_distribution(
8, vp8_small_mvencodings, vp8_small_mvtree,
p, short_bct, short_ct,
256, 1
);
do
calc_prob(Pnew + MVPshort + j, short_bct[j]);
while (++j < mvnum_short - 1);
}
{
int j = 0;
do
calc_prob(Pnew + MVPbits + j, bit_ct[j]);
while (++j < mvlong_width);
}
update(w, is_short_ct, Pcur + mvpis_short, Pnew[mvpis_short], *Pupdate++, updated);
update(w, sign_ct, Pcur + MVPsign, Pnew[MVPsign], *Pupdate++, updated);
{
const vp8_prob *const new_p = Pnew + MVPshort;
vp8_prob *const cur_p = Pcur + MVPshort;
int j = 0;
do
update(w, short_bct[j], cur_p + j, new_p[j], *Pupdate++, updated);
while (++j < mvnum_short - 1);
}
{
const vp8_prob *const new_p = Pnew + MVPbits;
vp8_prob *const cur_p = Pcur + MVPbits;
int j = 0;
do
update(w, bit_ct[j], cur_p + j, new_p[j], *Pupdate++, updated);
while (++j < mvlong_width);
}
}
void vp8_write_mvprobs(VP8_COMP *cpi)
{
vp8_writer *const w = cpi->bc;
MV_CONTEXT *mvc = cpi->common.fc.mvc;
int flags[2] = {0, 0};
#ifdef VP8_ENTROPY_STATS
active_section = 4;
#endif
write_component_probs(
w, &mvc[0], &vp8_default_mv_context[0], &vp8_mv_update_probs[0],
cpi->mb.MVcount[0], 0, &flags[0]
);
write_component_probs(
w, &mvc[1], &vp8_default_mv_context[1], &vp8_mv_update_probs[1],
cpi->mb.MVcount[1], 1, &flags[1]
);
if (flags[0] || flags[1])
vp8_build_component_cost_table(cpi->mb.mvcost, (const MV_CONTEXT *) cpi->common.fc.mvc, flags);
#ifdef VP8_ENTROPY_STATS
active_section = 5;
#endif
}