Non-rd pickmode: Don't skip checking zeromv-last mode.

Reference frame masking logic may skip checking zeromv-last mode.
Fix to avoid this and make sure zero-last is always checked.

No noticeable change in speed, and PSNR/SSIM metrics on RTC set overall
neutral (very small gain ~0.02).
Small visual improvement on few RTC clips.

Change-Id: I26eacdc449126424001a4a64e5ac31949f064417

diff --git a/vp9/encoder/vp9_pickmode.c b/vp9/encoder/vp9_pickmode.c
index 19b0beb347c00f461d532b0f03f95b218ab5538e..5a4b26a92e78e3dc65ac667ff9f43f4ae7fed778 100644 (file)
--- a/vp9/encoder/vp9_pickmode.c
+++ b/vp9/encoder/vp9_pickmode.c
@@ -1238,10 +1238,12 @@ void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
     if (const_motion[ref_frame] && this_mode == NEARMV)
       continue;
 
-    i = (ref_frame == LAST_FRAME) ? GOLDEN_FRAME : LAST_FRAME;
-    if ((cpi->ref_frame_flags & flag_list[i]) && sf->reference_masking)
-      if (x->pred_mv_sad[ref_frame] > (x->pred_mv_sad[i] << 1))
-        ref_frame_skip_mask |= (1 << ref_frame);
+    if (!(this_mode == ZEROMV && ref_frame == LAST_FRAME)) {
+      i = (ref_frame == LAST_FRAME) ? GOLDEN_FRAME : LAST_FRAME;
+      if ((cpi->ref_frame_flags & flag_list[i]) && sf->reference_masking)
+        if (x->pred_mv_sad[ref_frame] > (x->pred_mv_sad[i] << 1))
+          ref_frame_skip_mask |= (1 << ref_frame);
+    }
     if (ref_frame_skip_mask & (1 << ref_frame))
       continue;