From 4e8acca92533d969892d7236d812899e45b9f904 Mon Sep 17 00:00:00 2001
From: Wei-ting Lin <weitinglin@google.com>
Date: Mon, 22 Aug 2016 11:19:30 -0700
Subject: [PATCH] Allow LF_UPDATE type of frames to use BWDREF
Originally, only bi-pred type of frames can use BWDREF. When
extra alt-refs are inserted in a gf group, the closest alt-ref
serves as ALTREF for the frames within the corresponding
subgroup. Therefore, the original alt-ref can be used as BWDREF
for the LF_UPDATE type of frames.
This patch further swaps the virtual indices of BWDREF and ALTREF
for those frames whose BWDREF is farther than ALTREF. As a result,
the BWDREF is always the closet backward reference frame, and the
ALTREF is the farther one.
It improves the average RD performance by
0.132% in lowres, and
0.030% in midres.
The overall gains for the ext-refs compared to the baseline are
5.486% in lowres, and
4.666% in midres.
Change-Id: I22e4e5f378f19c4c89196a0a5e9214adb46c3428
---
vp10/encoder/encoder.c | 12 ++++++++++--
vp10/encoder/firstpass.c | 18 +++++++++++++++---
2 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/vp10/encoder/encoder.c b/vp10/encoder/encoder.c
index 266c02dccd..dfafb2a753 100644
--- a/vp10/encoder/encoder.c
+++ b/vp10/encoder/encoder.c
@@ -3260,7 +3260,8 @@ void vp10_update_reference_frames(VP10_COMP *cpi) {
// NOTE: The ALT_REFs' are indexed reversely, and ALT0 refers to the
// farthest ALT_REF from the first frame in the gf group.
int tmp = cpi->arf_map[0];
- cpi->arf_map[0] = cpi->bwd_fb_idx;
+ cpi->arf_map[0] = cpi->alt_fb_idx;
+ cpi->alt_fb_idx = cpi->bwd_fb_idx;
cpi->bwd_fb_idx = tmp;
}
ref_cnt_fb(pool->frame_bufs, &cm->ref_frame_map[cpi->bwd_fb_idx],
@@ -3309,7 +3310,14 @@ void vp10_update_reference_frames(VP10_COMP *cpi) {
// v v v
// lst_fb_idxes[2], lst_fb_idxes[0], lst_fb_idxes[1]
int ref_frame;
-
+ if (cpi->rc.is_bwd_ref_frame && cpi->num_extra_arfs) {
+ // We have swapped the virtual indices to use ALT0 as BWD_REF
+ // and we need to swap them back.
+ int tmp = cpi->arf_map[0];
+ cpi->arf_map[0] = cpi->alt_fb_idx;
+ cpi->alt_fb_idx = cpi->bwd_fb_idx;
+ cpi->bwd_fb_idx = tmp;
+ }
if (cm->frame_type == KEY_FRAME) {
for (ref_frame = 0; ref_frame < LAST_REF_FRAMES; ++ref_frame) {
ref_cnt_fb(pool->frame_bufs,
diff --git a/vp10/encoder/firstpass.c b/vp10/encoder/firstpass.c
index 1d1bf52016..2b3c85f783 100644
--- a/vp10/encoder/firstpass.c
+++ b/vp10/encoder/firstpass.c
@@ -2578,7 +2578,18 @@ static void configure_buffer_updates(VP10_COMP *cpi) {
cpi->refresh_last_frame = 1;
cpi->refresh_golden_frame = 0;
#if CONFIG_EXT_REFS
- cpi->refresh_bwd_ref_frame = 0;
+ // If we have extra ALT_REFs, we can use the farthest ALT (ALT0) as
+ // the BWD_REF.
+ if (cpi->num_extra_arfs) {
+ int tmp = cpi->bwd_fb_idx;
+
+ cpi->rc.is_bwd_ref_frame = 1;
+ cpi->bwd_fb_idx = cpi->alt_fb_idx;
+ cpi->alt_fb_idx = cpi->arf_map[0];;
+ cpi->arf_map[0] = tmp;
+ } else {
+ cpi->rc.is_bwd_ref_frame = 0;
+ }
#endif // CONFIG_EXT_REFS
cpi->refresh_alt_ref_frame = 0;
break;
@@ -2619,12 +2630,13 @@ static void configure_buffer_updates(VP10_COMP *cpi) {
cpi->refresh_alt_ref_frame = 0;
cpi->rc.is_bwd_ref_frame = 1;
if (cpi->num_extra_arfs) {
- // Allow BRF uses the farthest ALT_REF (ALT0) as BWD_REF by swapping
+ // Allow BRF use the farthest ALT_REF (ALT0) as BWD_REF by swapping
// the virtual indices.
// NOTE: The indices will be swapped back after this frame is encoded
// (in vp10_update_reference_frames()).
int tmp = cpi->bwd_fb_idx;
- cpi->bwd_fb_idx = cpi->arf_map[0];
+ cpi->bwd_fb_idx = cpi->alt_fb_idx;
+ cpi->alt_fb_idx = cpi->arf_map[0];
cpi->arf_map[0] = tmp;
}
break;
--
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