Skip RD check for compound modes that have same sign bias

The compound mode can only be run between two reference frames
with different sign bias flags. Skip the search over same sign
bias reference frames in the rate-distortion optimization.

Change-Id: I4a57feedea880883cf87200de51862beac108310

diff --git a/vp9/encoder/vp9_rdopt.c b/vp9/encoder/vp9_rdopt.c
index 1f1cd40..3c15af3 100644 (file)
--- a/vp9/encoder/vp9_rdopt.c
+++ b/vp9/encoder/vp9_rdopt.c
@@ -3350,6 +3350,10 @@ void vp9_rd_pick_inter_mode_sb(VP9_COMP *cpi, TileDataEnc *tile_data,
     if (comp_pred) {
       if (!cpi->allow_comp_inter_inter) continue;
 
+      if (cm->ref_frame_sign_bias[ref_frame] ==
+          cm->ref_frame_sign_bias[second_ref_frame])
+        continue;
+
       // Skip compound inter modes if ARF is not available.
       if (!(cpi->ref_frame_flags & flag_list[second_ref_frame])) continue;