From bc40b13f33de2e3cf8942659c35a84d8d65b8401 Mon Sep 17 00:00:00 2001
From: Jingning Han <jingning@google.com>
Date: Thu, 20 Sep 2018 10:03:27 -0700
Subject: [PATCH] Generalize encoder comp_var_ref setting

Generalize the encoder comp_fixed_ref and comp_var_ref assignments.
Make it fully support 2 fwd + 1 bwd and 1 fwd + 2 bwd settings
that VP9 decoder allows.

Change-Id: Id74da9a66327189a3fdf382d447243003c431131
---
 vp9/common/vp9_pred_common.c  | 18 ++++++++++++++++++
 vp9/common/vp9_pred_common.h  |  2 ++
 vp9/decoder/vp9_decodeframe.c | 20 +-------------------
 vp9/encoder/vp9_encodeframe.c |  4 +---
 4 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/vp9/common/vp9_pred_common.c b/vp9/common/vp9_pred_common.c
index 15c7e6376..51d120717 100644
--- a/vp9/common/vp9_pred_common.c
+++ b/vp9/common/vp9_pred_common.c
@@ -13,6 +13,24 @@
 #include "vp9/common/vp9_pred_common.h"
 #include "vp9/common/vp9_seg_common.h"
 
+void vp9_setup_compound_reference_mode(VP9_COMMON *cm) {
+  if (cm->ref_frame_sign_bias[LAST_FRAME] ==
+      cm->ref_frame_sign_bias[GOLDEN_FRAME]) {
+    cm->comp_fixed_ref = ALTREF_FRAME;
+    cm->comp_var_ref[0] = LAST_FRAME;
+    cm->comp_var_ref[1] = GOLDEN_FRAME;
+  } else if (cm->ref_frame_sign_bias[LAST_FRAME] ==
+             cm->ref_frame_sign_bias[ALTREF_FRAME]) {
+    cm->comp_fixed_ref = GOLDEN_FRAME;
+    cm->comp_var_ref[0] = LAST_FRAME;
+    cm->comp_var_ref[1] = ALTREF_FRAME;
+  } else {
+    cm->comp_fixed_ref = LAST_FRAME;
+    cm->comp_var_ref[0] = GOLDEN_FRAME;
+    cm->comp_var_ref[1] = ALTREF_FRAME;
+  }
+}
+
 int vp9_get_reference_mode_context(const VP9_COMMON *cm,
                                    const MACROBLOCKD *xd) {
   int ctx;
diff --git a/vp9/common/vp9_pred_common.h b/vp9/common/vp9_pred_common.h
index e2f17f251..7806da82f 100644
--- a/vp9/common/vp9_pred_common.h
+++ b/vp9/common/vp9_pred_common.h
@@ -145,6 +145,8 @@ static INLINE vpx_prob vp9_get_pred_prob_single_ref_p2(const VP9_COMMON *cm,
   return cm->fc->single_ref_prob[vp9_get_pred_context_single_ref_p2(xd)][1];
 }
 
+void vp9_setup_compound_reference_mode(VP9_COMMON *cm);
+
 // Returns a context number for the given MB prediction signal
 // The mode info data structure has a one element border above and to the
 // left of the entries corresponding to real blocks.
diff --git a/vp9/decoder/vp9_decodeframe.c b/vp9/decoder/vp9_decodeframe.c
index 68691ba93..cd7c16a18 100644
--- a/vp9/decoder/vp9_decodeframe.c
+++ b/vp9/decoder/vp9_decodeframe.c
@@ -53,24 +53,6 @@ static int is_compound_reference_allowed(const VP9_COMMON *cm) {
   return 0;
 }
 
-static void setup_compound_reference_mode(VP9_COMMON *cm) {
-  if (cm->ref_frame_sign_bias[LAST_FRAME] ==
-      cm->ref_frame_sign_bias[GOLDEN_FRAME]) {
-    cm->comp_fixed_ref = ALTREF_FRAME;
-    cm->comp_var_ref[0] = LAST_FRAME;
-    cm->comp_var_ref[1] = GOLDEN_FRAME;
-  } else if (cm->ref_frame_sign_bias[LAST_FRAME] ==
-             cm->ref_frame_sign_bias[ALTREF_FRAME]) {
-    cm->comp_fixed_ref = GOLDEN_FRAME;
-    cm->comp_var_ref[0] = LAST_FRAME;
-    cm->comp_var_ref[1] = ALTREF_FRAME;
-  } else {
-    cm->comp_fixed_ref = LAST_FRAME;
-    cm->comp_var_ref[0] = GOLDEN_FRAME;
-    cm->comp_var_ref[1] = ALTREF_FRAME;
-  }
-}
-
 static int read_is_valid(const uint8_t *start, size_t len, const uint8_t *end) {
   return len != 0 && len <= (size_t)(end - start);
 }
@@ -2049,7 +2031,7 @@ static int read_compressed_header(VP9Decoder *pbi, const uint8_t *data,
 
     cm->reference_mode = read_frame_reference_mode(cm, &r);
     if (cm->reference_mode != SINGLE_REFERENCE)
-      setup_compound_reference_mode(cm);
+      vp9_setup_compound_reference_mode(cm);
     read_frame_reference_mode_probs(cm, &r);
 
     for (j = 0; j < BLOCK_SIZE_GROUPS; j++)
diff --git a/vp9/encoder/vp9_encodeframe.c b/vp9/encoder/vp9_encodeframe.c
index 702f8c2ea..4c131bb60 100644
--- a/vp9/encoder/vp9_encodeframe.c
+++ b/vp9/encoder/vp9_encodeframe.c
@@ -5487,9 +5487,7 @@ void vp9_encode_frame(VP9_COMP *cpi) {
       cpi->allow_comp_inter_inter = 0;
     } else {
       cpi->allow_comp_inter_inter = 1;
-      cm->comp_fixed_ref = ALTREF_FRAME;
-      cm->comp_var_ref[0] = LAST_FRAME;
-      cm->comp_var_ref[1] = GOLDEN_FRAME;
+      vp9_setup_compound_reference_mode(cm);
     }
   }
 
-- 
2.40.0