shithub: libvpx

Download patch

ref: e3465a63d7453bcdbbe09eaca1d3b9d648df6ef4
parent: 421ad3f1b12106bbac7a43be1b14f0e82a8ff4d3
author: Yaowu Xu <yaowu@google.com>
date: Fri Apr 19 05:33:07 EDT 2013 

make DC_PRED for i4x4 to use real pixels only

Wherever there are real pixels available before falling back to use
assumed values 127 and 129.

This also make DC_PRED for i4x4 consistent with DC_PRED for larger
blocks.

Change-Id: I54372924826118da023f402c802ac6ce0caa70c3


--- a/vp9/common/vp9_reconintra4x4.c
+++ b/vp9/common/vp9_reconintra4x4.c
@@ -258,15 +258,22 @@
 
   switch (b_mode) {
     case B_DC_PRED: {
-      int expected_dc = 0;
-
-      for (i = 0; i < 4; i++) {
-        expected_dc += above[i];
-        expected_dc += left[i];
+      int expected_dc = 128;
+      if (have_top || have_left) {
+        int average = 0;
+        int count = 0;
+        if (have_top) {
+          for (i = 0; i < 4; i++)
+            average += above[i];
+          count += 4;
+        }
+        if (have_left) {
+          for (i = 0; i < 4; i++)
+            average += left[i];
+          count += 4;
+        }
+        expected_dc = (average + (count >> 1)) / count;
       }
-
-      expected_dc = ROUND_POWER_OF_TWO(expected_dc, 3);
-
       for (r = 0; r < 4; r++) {
         for (c = 0; c < 4; c++)
           predictor[c] = expected_dc;
-- 
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