commit c4048dbdd39dbd4763852a6d0a27f183677c4225
author Yaowu Xu <yaowu@google.com> Sat Aug 10 15:04:02 2013 -0700
committer Yaowu Xu <yaowu@google.com> Mon Aug 19 17:19:36 2013 -0700
tree 1626130bc5bf65f6a9f61f203eec932908fcb449
parent f70330a906fc42bbb6f7100ed1ad5800007b96bc

Change to limit the mv search range

As the pixel values beyond image border are duplicates of pixels
on edge, the change limits the mv search range, any mv beyond
the limits no longer produce new/different prediction values
as entire block with pixels used for subpel interpolation are
outside image border.

Change-Id: I4c6fdf06e33c1cef1489f5470ce0fb4e5e01fb79

vp9/common/vp9_enums.h

diff --git a/vp9/common/vp9_enums.h b/vp9/common/vp9_enums.h
index 435460e..2720386 100644
--- a/vp9/common/vp9_enums.h
+++ b/vp9/common/vp9_enums.h
@@ -16,11 +16,13 @@
 #define LOG2_MI_SIZE 3
 #define LOG2_MI_BLOCK_SIZE (6 - LOG2_MI_SIZE)  // 64 = 2^6
 
+#define MAX_BLOCK_SIZE (1 << 6)  // max block size in pixel
 #define MI_SIZE (1 << LOG2_MI_SIZE)  // pixels per mi-unit
 #define MI_BLOCK_SIZE (1 << LOG2_MI_BLOCK_SIZE)  // mi-units per max block
 
 #define MI_MASK (MI_BLOCK_SIZE - 1)
 
+
 typedef enum BLOCK_SIZE_TYPE {
   BLOCK_4X4,
   BLOCK_4X8,

vp9/encoder/vp9_encodeframe.c

diff --git a/vp9/encoder/vp9_encodeframe.c b/vp9/encoder/vp9_encodeframe.c
index 65725bf..932ca62 100644
--- a/vp9/encoder/vp9_encodeframe.c
+++ b/vp9/encoder/vp9_encodeframe.c
@@ -516,14 +516,12 @@
   // Set up destination pointers
   setup_dst_planes(xd, &cm->yv12_fb[dst_fb_idx], mi_row, mi_col);
 
-  /* Set up limit values for MV components to prevent them from
-   * extending beyond the UMV borders assuming 16x16 block size */
-  x->mv_row_min = -((mi_row * MI_SIZE)+ VP9BORDERINPIXELS - VP9_INTERP_EXTEND);
-  x->mv_col_min = -((mi_col * MI_SIZE)+ VP9BORDERINPIXELS - VP9_INTERP_EXTEND);
-  x->mv_row_max = ((cm->mi_rows - mi_row) * MI_SIZE
-      + (VP9BORDERINPIXELS - MI_SIZE * mi_height - VP9_INTERP_EXTEND));
-  x->mv_col_max = ((cm->mi_cols - mi_col) * MI_SIZE
-      + (VP9BORDERINPIXELS - MI_SIZE * mi_width - VP9_INTERP_EXTEND));
+  // Set up limit values for MV components
+  // mv beyond the range do not produce new/different prediction block
+  x->mv_row_min = -((mi_row * MI_SIZE) + MAX_BLOCK_SIZE + VP9_INTERP_EXTEND);
+  x->mv_col_min = -((mi_col * MI_SIZE) + MAX_BLOCK_SIZE + VP9_INTERP_EXTEND);
+  x->mv_row_max = (cm->mi_rows - mi_row) * MI_SIZE + VP9_INTERP_EXTEND;
+  x->mv_col_max = (cm->mi_cols - mi_col) * MI_SIZE + VP9_INTERP_EXTEND;
 
   // Set up distance of MB to edge of frame in 1/8th pel units
   assert(!(mi_col & (mi_width - 1)) && !(mi_row & (mi_height - 1)));