change scale down by 4 to use rounding.

unit_test/scale_test.cc

 /*
  *  Copyright 2011 The LibYuv Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS. All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 280 matching lines @@
       int diff = TestFilter_16(SX(benchmark_width_, nom, denom),               \
                                SX(benchmark_height_, nom, denom),              \
                                DX(benchmark_width_, nom, denom),               \
                                DX(benchmark_height_, nom, denom),              \
                                kFilter##filter, benchmark_iterations_);        \
       EXPECT_LE(diff, max_diff);                                               \
     }
 
 // Test a scale factor with all 4 filters.  Expect unfiltered to be exact, but
 // filtering is different fixed point implementations for SSSE3, Neon and C.
-#define TEST_FACTOR(name, nom, denom, maxdiff)                                 \
+#define TEST_FACTOR(name, nom, denom, boxdiff)                                 \
     TEST_FACTOR1(name, None, nom, denom, 0)                                    \
-    TEST_FACTOR1(name, Linear, nom, denom, maxdiff)                            \
-    TEST_FACTOR1(name, Bilinear, nom, denom, maxdiff)                          \
-    TEST_FACTOR1(name, Box, nom, denom, maxdiff)
+    TEST_FACTOR1(name, Linear, nom, denom, 3)                                  \
+    TEST_FACTOR1(name, Bilinear, nom, denom, 3)                                \
+    TEST_FACTOR1(name, Box, nom, denom, boxdiff)
 
 TEST_FACTOR(2, 1, 2, 0)
-TEST_FACTOR(4, 1, 4, 3)
+TEST_FACTOR(4, 1, 4, 0)
 TEST_FACTOR(8, 1, 8, 3)
-TEST_FACTOR(3by4, 3, 4, 3)
-TEST_FACTOR(3by8, 3, 8, 3)
+TEST_FACTOR(3by4, 3, 4, 1)
+TEST_FACTOR(3by8, 3, 8, 1)
 TEST_FACTOR(3, 1, 3, 3)
 #undef TEST_FACTOR1
 #undef TEST_FACTOR
 #undef SX
 #undef DX
 
 #define TEST_SCALETO1(name, width, height, filter, max_diff)                   \
     TEST_F(LibYUVScaleTest, name##To##width##x##height##_##filter) {           \
       int diff = TestFilter(benchmark_width_, benchmark_height_,               \
                             width, height,                                     \
@@ skipping 33 matching lines @@
 TEST_SCALETO(Scale, 1, 1)
 TEST_SCALETO(Scale, 320, 240)
 TEST_SCALETO(Scale, 352, 288)
 TEST_SCALETO(Scale, 569, 480)
 TEST_SCALETO(Scale, 640, 360)
 TEST_SCALETO(Scale, 1280, 720)
 #undef TEST_SCALETO1
 #undef TEST_SCALETO
 
 }  // namespace libyuv