commit c41a549a014321c0cfd0d719d7737ca33ffcc482
author Jingning Han <jingning@google.com> Fri Feb 24 11:18:52 2017 -0800
committer Jingning Han <jingning@google.com> Tue Feb 28 07:04:12 2017 +0000
tree 6896ce1dbb23582fc155655f41515b77bc8ed338
parent 1e2aae1ae7b9fe4794c1be362a2c8e0e314e0a0a

Disable compound mode in sub8x8 coding blocks

Disable the support of compound prediction modes for sub8x8 codking
blocks. Make the rate-distortion optimizations process account for
such constraints.

With the use 2x2 chroma prediction block, this makes the wrost case
number of inter predictors same as vp9. It affects the coding
gains by 0.35% for lowres, 0.17% for midres, and 0.08% for hdres.

The encoding speed is up by 10%.

Change-Id: Ieb2a83030676911baa403e586f1f800cbf485d81

av1/encoder/bitstream.c

diff --git a/av1/encoder/bitstream.c b/av1/encoder/bitstream.c
index d218eb0..9b8eeac 100644
--- a/av1/encoder/bitstream.c
+++ b/av1/encoder/bitstream.c
@@ -1040,7 +1040,12 @@
     // does the feature use compound prediction or not
     // (if not specified at the frame/segment level)
     if (cm->reference_mode == REFERENCE_MODE_SELECT) {
+#if SUB8X8_COMP_REF
       aom_write(w, is_compound, av1_get_reference_mode_prob(cm, xd));
+#else
+      if (mbmi->sb_type >= BLOCK_8X8)
+        aom_write(w, is_compound, av1_get_reference_mode_prob(cm, xd));
+#endif
     } else {
       assert((!is_compound) == (cm->reference_mode == SINGLE_REFERENCE));
     }