New Motion Reference Search

Alternative strategy for finding a list of candidate motion
vectors to use as reference values in mv coding and as
nearest and near.

Sort by sad in vp8_find_best_ref_mvs() rather than just
pick the best. Allow 0,0 as a best ref option but not a
nearest or near unless there are no alternatives.

Encode/Decode verified on at least some clips.

Some commented out experimental and stats code still in place.

Gain over existing code averages about 1% on derf (alll metrics)
with improvement on all clips. Other test results pending.

The entropy coding of the mode (nearest/near etc) still
depends upon and requires the old "findnear" code so
this needs looking at and may provide room for further gains.

Change-Id: I871d7cba1d1c379c4bad9bcccce1fb19c46b8247

1 files changed, 35 insertions, 0 deletions

diff --git a/vp8/decoder/decodemv.c b/vp8/decoder/decodemv.c
index 5e0600c2d..069d073d4 100644
--- a/vp8/decoder/decodemv.c
+++ b/vp8/decoder/decodemv.c
@@ -657,6 +657,7 @@ static void read_mb_modes_mv(VP8D_COMP *pbi, MODE_INFO *mi, MB_MODE_INFO *mbmi,
                       prev_mi,
                       &nearest, &nearby, &best_mv, rct,
                       mbmi->ref_frame, cm->ref_frame_sign_bias);
+
 #if CONFIG_NEWBESTREFMV
     {
       int ref_fb_idx;
@@ -679,6 +680,23 @@ static void read_mb_modes_mv(VP8D_COMP *pbi, MODE_INFO *mi, MB_MODE_INFO *mbmi,
       xd->pre.u_buffer = cm->yv12_fb[ref_fb_idx].u_buffer + recon_uvoffset;
       xd->pre.v_buffer = cm->yv12_fb[ref_fb_idx].v_buffer + recon_uvoffset;
 
+#if CONFIG_NEW_MVREF
+      // Update stats on relative distance of chosen vector to the
+      // possible best reference vectors.
+      {
+        int i;
+        MV_REFERENCE_FRAME ref_frame = mbmi->ref_frame;
+
+        find_mv_refs(xd, mi, prev_mi,
+                     ref_frame, mbmi->ref_mvs[ref_frame],
+                     cm->ref_frame_sign_bias );
+
+        // Copy over the candidates.
+        vpx_memcpy(xd->ref_mv, mbmi->ref_mvs[ref_frame],
+                   (MAX_MV_REFS * sizeof(int_mv)) );
+      }
+#endif
+
       vp8_find_best_ref_mvs(xd,
                             xd->pre.y_buffer,
                             recon_y_stride,
@@ -763,6 +781,23 @@ static void read_mb_modes_mv(VP8D_COMP *pbi, MODE_INFO *mi, MB_MODE_INFO *mbmi,
                           rct,
                           mbmi->second_ref_frame,
                           cm->ref_frame_sign_bias);
+
+#if CONFIG_NEW_MVREF
+        // Update stats on relative distance of chosen vector to the
+        // possible best reference vectors.
+        {
+          MV_REFERENCE_FRAME ref_frame = mbmi->second_ref_frame;
+
+          find_mv_refs(xd, mi, prev_mi,
+                       ref_frame, mbmi->ref_mvs[ref_frame],
+                       cm->ref_frame_sign_bias );
+
+          // Copy over the mv candidates
+          vpx_memcpy(xd->ref_mv, mbmi->ref_mvs[ref_frame],
+                    (MAX_MV_REFS * sizeof(int_mv)) );
+        }
+#endif
+
         vp8_find_best_ref_mvs(xd,
                               xd->second_pre.y_buffer,
                               recon_y_stride,