vpx/vp9/common/vp9_mvref_common.c
Paul Wilkins 92e8a3f514 Simplification of MVref search.
As we are no longer able to sort the candidate
mvrefs in both encoder and decode and given
that the cost of explicit signalling has proved
prohibitive, it no longer makes sense to find more
than 2 candidates.

This patch:

Modifies and simplifies add_candidate_mv()

Removes the forced addition of a 0 vector in the
MAX_MV_REF_CANDIDATES-1 position (in preparation
to reducing MAX_MV_REF_CANDIDATES to 2).

Re-orders the addition of candidates slightly.

This actually gives small gains (circa 0.2% on std-hd)

A subsequent patch will remove NEW_MVREF experiment,
reduce MAX_MV_REF_CANDIDATES to 2 and remove distance
weights as these are implicit now in the order.

Change-Id: I3dbe1a6f8a1a18b3c108257069c22a1141a207a4
2013-04-19 11:19:59 +01:00

322 lines
12 KiB
C

/*
* Copyright (c) 2012 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 "vp9/common/vp9_mvref_common.h"
#define MVREF_NEIGHBOURS 8
static int mb_mv_ref_search[MVREF_NEIGHBOURS][2] = {
{0, -1}, {-1, 0}, {-1, -1}, {0, -2},
{-2, 0}, {-1, -2}, {-2, -1}, {-2, -2}
};
static int mb_ref_distance_weight[MVREF_NEIGHBOURS] =
{ 3, 3, 2, 1, 1, 1, 1, 1 };
static int sb_mv_ref_search[MVREF_NEIGHBOURS][2] = {
{0, -1}, {-1, 0}, {1, -1}, {-1, 1},
{-1, -1}, {0, -2}, {-2, 0}, {-1, -2}
};
static int sb_ref_distance_weight[MVREF_NEIGHBOURS] =
{ 3, 3, 2, 2, 2, 1, 1, 1 };
static int sb64_mv_ref_search[MVREF_NEIGHBOURS][2] = {
{0, -1}, {-1, 0}, {1, -1}, {-1, 1},
{2, -1}, {-1, 2}, {3, -1}, {-1,-1}
};
static int sb64_ref_distance_weight[MVREF_NEIGHBOURS] =
{ 1, 1, 1, 1, 1, 1, 1, 1 };
// clamp_mv_ref
#define MV_BORDER (16 << 3) // Allow 16 pels in 1/8th pel units
static void clamp_mv_ref(const MACROBLOCKD *xd, int_mv *mv) {
mv->as_mv.col = clamp(mv->as_mv.col, xd->mb_to_left_edge - MV_BORDER,
xd->mb_to_right_edge + MV_BORDER);
mv->as_mv.row = clamp(mv->as_mv.row, xd->mb_to_top_edge - MV_BORDER,
xd->mb_to_bottom_edge + MV_BORDER);
}
// Gets a candidate refenence motion vector from the given mode info
// structure if one exists that matches the given reference frame.
static int get_matching_candidate(const MODE_INFO *candidate_mi,
MV_REFERENCE_FRAME ref_frame,
int_mv *c_mv) {
if (ref_frame == candidate_mi->mbmi.ref_frame) {
c_mv->as_int = candidate_mi->mbmi.mv[0].as_int;
} else if (ref_frame == candidate_mi->mbmi.second_ref_frame) {
c_mv->as_int = candidate_mi->mbmi.mv[1].as_int;
} else {
return 0;
}
return 1;
}
// Gets candidate refenence motion vector(s) from the given mode info
// structure if they exists and do NOT match the given reference frame.
static void get_non_matching_candidates(const MODE_INFO *candidate_mi,
MV_REFERENCE_FRAME ref_frame,
MV_REFERENCE_FRAME *c_ref_frame,
int_mv *c_mv,
MV_REFERENCE_FRAME *c2_ref_frame,
int_mv *c2_mv) {
c_mv->as_int = 0;
c2_mv->as_int = 0;
*c_ref_frame = INTRA_FRAME;
*c2_ref_frame = INTRA_FRAME;
// If first candidate not valid neither will be.
if (candidate_mi->mbmi.ref_frame > INTRA_FRAME) {
// First candidate
if (candidate_mi->mbmi.ref_frame != ref_frame) {
*c_ref_frame = candidate_mi->mbmi.ref_frame;
c_mv->as_int = candidate_mi->mbmi.mv[0].as_int;
}
// Second candidate
if ((candidate_mi->mbmi.second_ref_frame > INTRA_FRAME) &&
(candidate_mi->mbmi.second_ref_frame != ref_frame) &&
(candidate_mi->mbmi.mv[1].as_int != candidate_mi->mbmi.mv[0].as_int)) {
*c2_ref_frame = candidate_mi->mbmi.second_ref_frame;
c2_mv->as_int = candidate_mi->mbmi.mv[1].as_int;
}
}
}
// Performs mv sign inversion if indicated by the reference frame combination.
static void scale_mv(MACROBLOCKD *xd, MV_REFERENCE_FRAME this_ref_frame,
MV_REFERENCE_FRAME candidate_ref_frame,
int_mv *candidate_mv, int *ref_sign_bias) {
// int frame_distances[MAX_REF_FRAMES];
// int last_distance = 1;
// int gf_distance = xd->frames_since_golden;
// int arf_distance = xd->frames_till_alt_ref_frame;
// Sign inversion where appropriate.
if (ref_sign_bias[candidate_ref_frame] != ref_sign_bias[this_ref_frame]) {
candidate_mv->as_mv.row = -candidate_mv->as_mv.row;
candidate_mv->as_mv.col = -candidate_mv->as_mv.col;
}
/*
// Scale based on frame distance if the reference frames not the same.
frame_distances[INTRA_FRAME] = 1; // should never be used
frame_distances[LAST_FRAME] = 1;
frame_distances[GOLDEN_FRAME] =
(xd->frames_since_golden) ? xd->frames_si nce_golden : 1;
frame_distances[ALTREF_FRAME] =
(xd->frames_till_alt_ref_frame) ? xd->frames_till_alt_ref_frame : 1;
if (frame_distances[this_ref_frame] &&
frame_distances[candidate_ref_frame]) {
candidate_mv->as_mv.row =
(short)(((int)(candidate_mv->as_mv.row) *
frame_distances[this_ref_frame]) /
frame_distances[candidate_ref_frame]);
candidate_mv->as_mv.col =
(short)(((int)(candidate_mv->as_mv.col) *
frame_distances[this_ref_frame]) /
frame_distances[candidate_ref_frame]);
}
*/
}
// Add a candidate mv.
// Discard if it has already been seen.
static void add_candidate_mv(int_mv *mv_list, int *mv_scores,
int *candidate_count, int_mv candidate_mv,
int weight) {
if (*candidate_count == 0) {
mv_list[0].as_int = candidate_mv.as_int;
mv_scores[0] = weight;
*candidate_count += 1;
} else if ((*candidate_count == 1) &&
(candidate_mv.as_int != mv_list[0].as_int)) {
mv_list[1].as_int = candidate_mv.as_int;
mv_scores[1] = weight;
*candidate_count += 1;
}
}
// This function searches the neighbourhood of a given MB/SB
// to try and find candidate reference vectors.
//
void vp9_find_mv_refs(VP9_COMMON *cm, MACROBLOCKD *xd, MODE_INFO *here,
MODE_INFO *lf_here, MV_REFERENCE_FRAME ref_frame,
int_mv *mv_ref_list, int *ref_sign_bias) {
int i;
MODE_INFO *candidate_mi;
MB_MODE_INFO * mbmi = &xd->mode_info_context->mbmi;
int_mv candidate_mvs[MAX_MV_REF_CANDIDATES];
int_mv c_refmv;
int_mv c2_refmv;
MV_REFERENCE_FRAME c_ref_frame;
MV_REFERENCE_FRAME c2_ref_frame;
int candidate_scores[MAX_MV_REF_CANDIDATES];
int refmv_count = 0;
int split_count = 0;
int (*mv_ref_search)[2];
int *ref_distance_weight;
const int mb_col = (-xd->mb_to_left_edge) >> 7;
// Blank the reference vector lists and other local structures.
vpx_memset(mv_ref_list, 0, sizeof(int_mv) * MAX_MV_REF_CANDIDATES);
vpx_memset(candidate_mvs, 0, sizeof(int_mv) * MAX_MV_REF_CANDIDATES);
vpx_memset(candidate_scores, 0, sizeof(candidate_scores));
if (mbmi->sb_type == BLOCK_SIZE_SB64X64) {
mv_ref_search = sb64_mv_ref_search;
ref_distance_weight = sb64_ref_distance_weight;
} else if (mbmi->sb_type >= BLOCK_SIZE_SB32X32) {
mv_ref_search = sb_mv_ref_search;
ref_distance_weight = sb_ref_distance_weight;
} else {
mv_ref_search = mb_mv_ref_search;
ref_distance_weight = mb_ref_distance_weight;
}
// We first scan for candidate vectors that match the current reference frame
// Look at nearest neigbours
for (i = 0; i < 2; ++i) {
const int mb_search_col = mb_col + mv_ref_search[i][0];
if ((mb_search_col >= cm->cur_tile_mb_col_start) &&
(mb_search_col < cm->cur_tile_mb_col_end) &&
((mv_ref_search[i][1] << 7) >= xd->mb_to_top_edge)) {
candidate_mi = here + mv_ref_search[i][0] +
(mv_ref_search[i][1] * xd->mode_info_stride);
if (get_matching_candidate(candidate_mi, ref_frame, &c_refmv)) {
add_candidate_mv(candidate_mvs, candidate_scores,
&refmv_count, c_refmv, ref_distance_weight[i] + 16);
}
split_count += (candidate_mi->mbmi.mode == SPLITMV);
}
}
// More distant neigbours
for (i = 2; (i < MVREF_NEIGHBOURS) &&
(refmv_count < MAX_MV_REF_CANDIDATES); ++i) {
const int mb_search_col = mb_col + mv_ref_search[i][0];
if ((mb_search_col >= cm->cur_tile_mb_col_start) &&
(mb_search_col < cm->cur_tile_mb_col_end) &&
((mv_ref_search[i][1] << 7) >= xd->mb_to_top_edge)) {
candidate_mi = here + mv_ref_search[i][0] +
(mv_ref_search[i][1] * xd->mode_info_stride);
if (get_matching_candidate(candidate_mi, ref_frame, &c_refmv)) {
add_candidate_mv(candidate_mvs, candidate_scores,
&refmv_count, c_refmv, ref_distance_weight[i] + 16);
}
}
}
// Look in the last frame if it exists
if (lf_here && (refmv_count < MAX_MV_REF_CANDIDATES)) {
candidate_mi = lf_here;
if (get_matching_candidate(candidate_mi, ref_frame, &c_refmv)) {
add_candidate_mv(candidate_mvs, candidate_scores,
&refmv_count, c_refmv, 17);
}
}
// If we have not found enough candidates consider ones where the
// reference frame does not match. Break out when we have
// MAX_MV_REF_CANDIDATES candidates.
// Look first at spatial neighbours
for (i = 0; (i < MVREF_NEIGHBOURS) &&
(refmv_count < MAX_MV_REF_CANDIDATES); ++i) {
const int mb_search_col = mb_col + mv_ref_search[i][0];
if ((mb_search_col >= cm->cur_tile_mb_col_start) &&
(mb_search_col < cm->cur_tile_mb_col_end) &&
((mv_ref_search[i][1] << 7) >= xd->mb_to_top_edge)) {
candidate_mi = here + mv_ref_search[i][0] +
(mv_ref_search[i][1] * xd->mode_info_stride);
get_non_matching_candidates(candidate_mi, ref_frame,
&c_ref_frame, &c_refmv,
&c2_ref_frame, &c2_refmv);
if (c_ref_frame != INTRA_FRAME) {
scale_mv(xd, ref_frame, c_ref_frame, &c_refmv, ref_sign_bias);
add_candidate_mv(candidate_mvs, candidate_scores,
&refmv_count, c_refmv, ref_distance_weight[i]);
}
if (c2_ref_frame != INTRA_FRAME) {
scale_mv(xd, ref_frame, c2_ref_frame, &c2_refmv, ref_sign_bias);
add_candidate_mv(candidate_mvs, candidate_scores,
&refmv_count, c2_refmv, ref_distance_weight[i]);
}
}
}
// Look at the last frame if it exists
if (lf_here && (refmv_count < MAX_MV_REF_CANDIDATES)) {
candidate_mi = lf_here;
get_non_matching_candidates(candidate_mi, ref_frame,
&c_ref_frame, &c_refmv,
&c2_ref_frame, &c2_refmv);
if (c_ref_frame != INTRA_FRAME) {
scale_mv(xd, ref_frame, c_ref_frame, &c_refmv, ref_sign_bias);
add_candidate_mv(candidate_mvs, candidate_scores,
&refmv_count, c_refmv, 1);
}
if (c2_ref_frame != INTRA_FRAME) {
scale_mv(xd, ref_frame, c2_ref_frame, &c2_refmv, ref_sign_bias);
add_candidate_mv(candidate_mvs, candidate_scores,
&refmv_count, c2_refmv, 1);
}
}
// Define inter mode coding context.
// 0,0 was best
if (candidate_mvs[0].as_int == 0) {
// 0,0 is only candidate
if (refmv_count <= 1) {
mbmi->mb_mode_context[ref_frame] = 0;
// non zero candidates candidates available
} else if (split_count == 0) {
mbmi->mb_mode_context[ref_frame] = 1;
} else {
mbmi->mb_mode_context[ref_frame] = 2;
}
} else if (split_count == 0) {
// Non zero best, No Split MV cases
mbmi->mb_mode_context[ref_frame] = candidate_scores[0] >= 16 ? 3 : 4;
} else {
// Non zero best, some split mv
mbmi->mb_mode_context[ref_frame] = candidate_scores[0] >= 16 ? 5 : 6;
}
// Scan for 0,0 case and clamp non zero choices
for (i = 0; i < MAX_MV_REF_CANDIDATES; ++i) {
clamp_mv_ref(xd, &candidate_mvs[i]);
}
// Copy over the candidate list.
vpx_memcpy(mv_ref_list, candidate_mvs, sizeof(candidate_mvs));
}