From 6a464eca0549fb1a539c9f5968d66e66cdf4cce9 Mon Sep 17 00:00:00 2001
From: Jingning Han <jingning@google.com>
Date: Mon, 18 Aug 2014 10:42:23 -0700
Subject: [PATCH] Speed up mode search depending on relative ref frame position

This commit enables the encoder to record the location of the
center frame to generate alter reference frame. It then allows to
skip checking prediction modes of other reference frame types when
it comes to encode this frame.

The speed 3 runtime is reduced for the test sequences:
bus at CIF 1000 kbps, 9791 ms -> 9446 ms, i.e., 3.5% speed-up,
pedestrian at 1080p 2000 kbps, 184043 ms -> 175730 ms, i.e., 4.5%
speed-up.

No compression performance change observed.

Change-Id: Iacfde3bcc1445964e7a241f239bd6ea11cb94bd1
---
 vp9/encoder/vp9_rdopt.c          | 19 +++++++++++++------
 vp9/encoder/vp9_speed_features.c |  2 ++
 vp9/encoder/vp9_speed_features.h |  2 ++
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/vp9/encoder/vp9_rdopt.c b/vp9/encoder/vp9_rdopt.c
index 517674e5f..9cb697e26 100644
--- a/vp9/encoder/vp9_rdopt.c
+++ b/vp9/encoder/vp9_rdopt.c
@@ -2632,6 +2632,12 @@ int64_t vp9_rd_pick_inter_mode_sb(VP9_COMP *cpi, MACROBLOCK *x,
     int64_t total_sse = INT64_MAX;
     int early_term = 0;
 
+    this_mode = vp9_mode_order[mode_index].mode;
+    ref_frame = vp9_mode_order[mode_index].ref_frame[0];
+    if (ref_frame != INTRA_FRAME && !(inter_mode_mask & (1 << this_mode)))
+      continue;
+    second_ref_frame = vp9_mode_order[mode_index].ref_frame[1];
+
     // Look at the reference frame of the best mode so far and set the
     // skip mask to look at a subset of the remaining modes.
     if (mode_index == mode_skip_start && best_mode_index >= 0) {
@@ -2653,6 +2659,13 @@ int64_t vp9_rd_pick_inter_mode_sb(VP9_COMP *cpi, MACROBLOCK *x,
           break;
       }
     }
+
+    if (cpi->sf.alt_ref_search_fp && cpi->rc.is_src_frame_alt_ref) {
+      mode_skip_mask = 0;
+      if (!(ref_frame == ALTREF_FRAME && second_ref_frame == NONE))
+        continue;
+    }
+
     if (mode_skip_mask & (1 << mode_index))
       continue;
 
@@ -2661,12 +2674,6 @@ int64_t vp9_rd_pick_inter_mode_sb(VP9_COMP *cpi, MACROBLOCK *x,
                             rd_thresh_freq_fact[mode_index]))
       continue;
 
-    this_mode = vp9_mode_order[mode_index].mode;
-    ref_frame = vp9_mode_order[mode_index].ref_frame[0];
-    if (ref_frame != INTRA_FRAME && !(inter_mode_mask & (1 << this_mode)))
-      continue;
-    second_ref_frame = vp9_mode_order[mode_index].ref_frame[1];
-
     if (cpi->sf.motion_field_mode_search) {
       const int mi_width  = MIN(num_8x8_blocks_wide_lookup[bsize],
                                 tile->mi_col_end - mi_col);
diff --git a/vp9/encoder/vp9_speed_features.c b/vp9/encoder/vp9_speed_features.c
index 67b6e269e..a2f4583a5 100644
--- a/vp9/encoder/vp9_speed_features.c
+++ b/vp9/encoder/vp9_speed_features.c
@@ -119,6 +119,7 @@ static void set_good_speed_feature(VP9_COMP *cpi, VP9_COMMON *cm,
     sf->adaptive_pred_interp_filter = 0;
     sf->cb_partition_search = frame_is_boosted(cpi) ? 0 : 1;
     sf->cb_pred_filter_search = 1;
+    sf->alt_ref_search_fp = 1;
     sf->motion_field_mode_search = frame_is_boosted(cpi) ? 0 : 1;
     sf->lf_motion_threshold = LOW_MOTION_THRESHOLD;
     sf->last_partitioning_redo_frequency = 3;
@@ -347,6 +348,7 @@ void vp9_set_speed_features(VP9_COMP *cpi) {
   sf->cb_pred_filter_search = 0;
   sf->cb_partition_search = 0;
   sf->motion_field_mode_search = 0;
+  sf->alt_ref_search_fp = 0;
   sf->use_quant_fp = 0;
   sf->reference_masking = 0;
   sf->partition_search_type = SEARCH_PARTITION;
diff --git a/vp9/encoder/vp9_speed_features.h b/vp9/encoder/vp9_speed_features.h
index 8edcb1d72..3e8215f0c 100644
--- a/vp9/encoder/vp9_speed_features.h
+++ b/vp9/encoder/vp9_speed_features.h
@@ -291,6 +291,8 @@ typedef struct SPEED_FEATURES {
 
   int motion_field_mode_search;
 
+  int alt_ref_search_fp;
+
   // Fast quantization process path
   int use_quant_fp;