ref: 4f35e3e1c1543f204fb5edac97e53bc467ec56ab
dir: /vp9/common/vp9_mvref_common.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 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 sb64_mv_ref_search[MVREF_NEIGHBOURS][2] = {
{0, -1}, {-1, 0}, {1, -1}, {-1, 1},
{2, -1}, {-1, 2}, {3, -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 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];
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_scores, 0, sizeof(candidate_scores));
if (mbmi->sb_type == BLOCK_SIZE_SB64X64) {
mv_ref_search = sb64_mv_ref_search;
} else if (mbmi->sb_type >= BLOCK_SIZE_SB32X32) {
mv_ref_search = sb_mv_ref_search;
} else {
mv_ref_search = mb_mv_ref_search;
}
// 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(mv_ref_list, candidate_scores,
&refmv_count, c_refmv, 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(mv_ref_list, candidate_scores,
&refmv_count, c_refmv, 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(mv_ref_list, candidate_scores,
&refmv_count, c_refmv, 16);
}
}
// 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(mv_ref_list, 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(mv_ref_list, candidate_scores,
&refmv_count, c2_refmv, 1);
}
}
}
// 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(mv_ref_list, 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(mv_ref_list, candidate_scores,
&refmv_count, c2_refmv, 1);
}
}
// Define inter mode coding context.
// 0,0 was best
if (mv_ref_list[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;
}
// Clamp vectors
for (i = 0; i < MAX_MV_REF_CANDIDATES; ++i) {
clamp_mv_ref(xd, &mv_ref_list[i]);
}
}