add yuvconvstants util

miscellaneous cleanup of other code/comments

Bug: libyuv:873, libyuv:877
Change-Id: I0d8caf9a65908ff8898b25494f7c724775f84fa3
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/2692930
Reviewed-by: Wan-Teh Chang <wtc@google.com>
Reviewed-by: Frank Barchard <fbarchard@chromium.org>

17 files changed, 205 insertions, 71 deletions

diff --git a/Android.bp b/Android.bp
index d0b23432..ae59dffb 100644
--- a/Android.bp
+++ b/Android.bp
@@ -145,3 +145,12 @@ cc_test {
     static_libs: ["libyuv"],
     shared_libs: ["libjpeg"],
 }
+
+cc_test {
+    name: "yuvconstants",
+    gtest: false,
+    srcs: [
+        "util/yuvconstants.cc",
+    ],
+    static_libs: ["libyuv"],
+}
diff --git a/BUILD.gn b/BUILD.gn
index d733e71d..40a67c79 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -41,6 +41,7 @@ group("default") {
       ":libyuv_unittest",
       ":psnr",
       ":yuvconvert",
+      ":yuvconstants",
     ]
   }
 }
@@ -357,6 +358,17 @@ if (libyuv_include_tests) {
     }
   }
 
+  executable("yuvconstants") {
+    sources = [
+      # sources
+      "util/yuvconstants.cc",
+    ]
+    deps = [ ":libyuv" ]
+    if (is_linux || is_chromeos) {
+      cflags = [ "-fexceptions" ]
+    }
+  }
+
   executable("psnr") {
     sources = [
       # sources
diff --git a/docs/deprecated_builds.md b/docs/deprecated_builds.md
index 29e0bf9b..ba42966c 100644
--- a/docs/deprecated_builds.md
+++ b/docs/deprecated_builds.md
@@ -239,6 +239,7 @@ If you get a compile error for atlthunk.lib on Windows, read http://www.chromium
     ninja -C out/Debug libyuv_unittest
     ninja -C out/Debug compare
     ninja -C out/Debug yuvconvert
+    ninja -C out/Debug yuvconstants
     ninja -C out/Debug psnr
     ninja -C out/Debug cpuid
 
diff --git a/docs/getting_started.md b/docs/getting_started.md
index 3e339712..e363c4ef 100644
--- a/docs/getting_started.md
+++ b/docs/getting_started.md
@@ -165,6 +165,7 @@ Running test with C code:
     ninja -C out/Debug libyuv_unittest
     ninja -C out/Debug compare
     ninja -C out/Debug yuvconvert
+    ninja -C out/Debug yuvconstants
     ninja -C out/Debug psnr
     ninja -C out/Debug cpuid
 
diff --git a/include/libyuv/convert_argb.h b/include/libyuv/convert_argb.h
index cf7f923e..297de151 100644
--- a/include/libyuv/convert_argb.h
+++ b/include/libyuv/convert_argb.h
@@ -22,17 +22,17 @@ extern "C" {
 
 // Conversion matrix for YUV to RGB
 LIBYUV_API extern const struct YuvConstants kYuvI601Constants;   // BT.601
-LIBYUV_API extern const struct YuvConstants kYuvJPEGConstants;   // JPeg
-LIBYUV_API extern const struct YuvConstants kYuvF709Constants;   // BT.709 full
+LIBYUV_API extern const struct YuvConstants kYuvJPEGConstants;   // BT.601 full
 LIBYUV_API extern const struct YuvConstants kYuvH709Constants;   // BT.709
+LIBYUV_API extern const struct YuvConstants kYuvF709Constants;   // BT.709 full
 LIBYUV_API extern const struct YuvConstants kYuv2020Constants;   // BT.2020
 LIBYUV_API extern const struct YuvConstants kYuvV2020Constants;  // BT.2020 full
 
 // Conversion matrix for YVU to BGR
 LIBYUV_API extern const struct YuvConstants kYvuI601Constants;   // BT.601
-LIBYUV_API extern const struct YuvConstants kYvuJPEGConstants;   // JPeg
-LIBYUV_API extern const struct YuvConstants kYvuF709Constants;   // BT.709 full
+LIBYUV_API extern const struct YuvConstants kYvuJPEGConstants;   // BT.601 full
 LIBYUV_API extern const struct YuvConstants kYvuH709Constants;   // BT.709
+LIBYUV_API extern const struct YuvConstants kYvuF709Constants;   // BT.709 full
 LIBYUV_API extern const struct YuvConstants kYvu2020Constants;   // BT.2020
 LIBYUV_API extern const struct YuvConstants kYvuV2020Constants;  // BT.2020 full
 
@@ -41,8 +41,8 @@ LIBYUV_API extern const struct YuvConstants kYvuV2020Constants;  // BT.2020 full
 // TODO(fbarchard): Add macro for each Matrix function.
 #define kYuvI601ConstantsVU kYvuI601Constants
 #define kYuvJPEGConstantsVU kYvuJPEGConstants
-#define kYuvF709ConstantsVU kYvuF709Constants
 #define kYuvH709ConstantsVU kYvuH709Constants
+#define kYuvF709ConstantsVU kYvuF709Constants
 #define kYuv2020ConstantsVU kYvu2020Constants
 #define kYuvV2020ConstantsVU kYvuV2020Constants
 
diff --git a/include/libyuv/scale_row.h b/include/libyuv/scale_row.h
index e972b533..18ffb546 100644
--- a/include/libyuv/scale_row.h
+++ b/include/libyuv/scale_row.h
@@ -612,13 +612,13 @@ void ScaleRowUp2_Bilinear_SSE2(const uint8_t* src_ptr,
                                ptrdiff_t dst_stride,
                                int dst_width);
 void ScaleRowUp2_Linear_16_SSSE3(const uint16_t* src_ptr,
-                                uint16_t* dst_ptr,
-                                int dst_width);
+                                 uint16_t* dst_ptr,
+                                 int dst_width);
 void ScaleRowUp2_Bilinear_16_SSSE3(const uint16_t* src_ptr,
-                                  ptrdiff_t src_stride,
-                                  uint16_t* dst_ptr,
-                                  ptrdiff_t dst_stride,
-                                  int dst_width);
+                                   ptrdiff_t src_stride,
+                                   uint16_t* dst_ptr,
+                                   ptrdiff_t dst_stride,
+                                   int dst_width);
 void ScaleRowUp2_Linear_SSSE3(const uint8_t* src_ptr,
                               uint8_t* dst_ptr,
                               int dst_width);
@@ -652,13 +652,13 @@ void ScaleRowUp2_Bilinear_Any_SSE2(const uint8_t* src_ptr,
                                    ptrdiff_t dst_stride,
                                    int dst_width);
 void ScaleRowUp2_Linear_16_Any_SSSE3(const uint16_t* src_ptr,
-                                    uint16_t* dst_ptr,
-                                    int dst_width);
+                                     uint16_t* dst_ptr,
+                                     int dst_width);
 void ScaleRowUp2_Bilinear_16_Any_SSSE3(const uint16_t* src_ptr,
-                                      ptrdiff_t src_stride,
-                                      uint16_t* dst_ptr,
-                                      ptrdiff_t dst_stride,
-                                      int dst_width);
+                                       ptrdiff_t src_stride,
+                                       uint16_t* dst_ptr,
+                                       ptrdiff_t dst_stride,
+                                       int dst_width);
 void ScaleRowUp2_Linear_Any_SSSE3(const uint8_t* src_ptr,
                                   uint8_t* dst_ptr,
                                   int dst_width);
diff --git a/include/libyuv/scale_uv.h b/include/libyuv/scale_uv.h
index 7b212178..8e74e319 100644
--- a/include/libyuv/scale_uv.h
+++ b/include/libyuv/scale_uv.h
@@ -30,7 +30,7 @@ int UVScale(const uint8_t* src_uv,
             int dst_height,
             enum FilterMode filtering);
 
-// Scale an 16 bit UV image.
+// Scale a 16 bit UV image.
 // This function is currently incomplete, it can't handle all cases.
 LIBYUV_API
 int UVScale_16(const uint16_t* src_uv,
diff --git a/linux.mk b/linux.mk
index 3e93b710..083f1fa2 100644
--- a/linux.mk
+++ b/linux.mk
@@ -66,7 +66,7 @@ LOCAL_OBJ_FILES := \
 .c.o:
 	$(CC) -c $(CFLAGS) $*.c -o $*.o
 
-all: libyuv.a i444tonv12_eg yuvconvert cpuid psnr
+all: libyuv.a i444tonv12_eg yuvconvert yuvconstants cpuid psnr
 
 libyuv.a: $(LOCAL_OBJ_FILES)
 	$(AR) $(ARFLAGS) $@ $(LOCAL_OBJ_FILES)
@@ -75,6 +75,10 @@ libyuv.a: $(LOCAL_OBJ_FILES)
 yuvconvert: util/yuvconvert.cc libyuv.a
 	$(CXX) $(CXXFLAGS) -Iutil/ -o $@ util/yuvconvert.cc libyuv.a
 
+# A C++ test utility that generates yuvconstants for yuv to rgb.
+yuvconstants: util/yuvconstants.cc libyuv.a
+	$(CXX) $(CXXFLAGS) -Iutil/ -o $@ util/yuvconstants.cc libyuv.a
+
 # A standalone test utility
 psnr: util/psnr.cc
 	$(CXX) $(CXXFLAGS) -Iutil/ -o $@ util/psnr.cc util/psnr_main.cc util/ssim.cc
@@ -90,4 +94,4 @@ cpuid: util/cpuid.c libyuv.a
 	$(CC) $(CFLAGS) -o $@ util/cpuid.c libyuv.a
 
 clean:
-	/bin/rm -f source/*.o *.ii *.s libyuv.a i444tonv12_eg yuvconvert cpuid psnr
+	/bin/rm -f source/*.o *.ii *.s libyuv.a i444tonv12_eg yuvconvert yuvconstants cpuid psnr
diff --git a/source/convert.cc b/source/convert.cc
index 8bf02b76..b0314df4 100644
--- a/source/convert.cc
+++ b/source/convert.cc
@@ -49,7 +49,7 @@ static int I4xxToI420(const uint8_t* src_y,
   const int dst_y_height = Abs(src_y_height);
   const int dst_uv_width = SUBSAMPLE(dst_y_width, 1, 1);
   const int dst_uv_height = SUBSAMPLE(dst_y_height, 1, 1);
-  if (src_uv_width == 0 || src_uv_height == 0) {
+  if (src_uv_width <= 0 || src_uv_height == 0) {
     return -1;
   }
   if (dst_y) {
@@ -625,7 +625,7 @@ int NV12ToNV24(const uint8_t* src_y,
                int dst_stride_uv,
                int width,
                int height) {
-  if (width == 0 || height == 0) {
+  if (width <= 0 || height == 0) {
     return -1;
   }
 
@@ -650,7 +650,7 @@ int NV16ToNV24(const uint8_t* src_y,
                int dst_stride_uv,
                int width,
                int height) {
-  if (width == 0 || height == 0) {
+  if (width <= 0 || height == 0) {
     return -1;
   }
 
@@ -674,7 +674,7 @@ int P010ToP410(const uint16_t* src_y,
                int dst_stride_uv,
                int width,
                int height) {
-  if (width == 0 || height == 0) {
+  if (width <= 0 || height == 0) {
     return -1;
   }
 
@@ -699,7 +699,7 @@ int P210ToP410(const uint16_t* src_y,
                int dst_stride_uv,
                int width,
                int height) {
-  if (width == 0 || height == 0) {
+  if (width <= 0 || height == 0) {
     return -1;
   }
 
diff --git a/source/row_gcc.cc b/source/row_gcc.cc
index c7e3fb95..cf87d46e 100644
--- a/source/row_gcc.cc
+++ b/source/row_gcc.cc
@@ -4444,7 +4444,7 @@ void SplitARGBRow_AVX2(const uint8_t* src_argb,
       "sub         %1,%3                         \n"
       "sub         %1,%4                         \n"
       "vmovdqa     %7,%%ymm3                     \n"
-      "vbroadcastf128 %6,%%ymm4                     \n"
+      "vbroadcastf128 %6,%%ymm4                  \n"
 
       LABELALIGN
       "1:                                        \n"
@@ -4491,7 +4491,7 @@ void SplitXRGBRow_AVX2(const uint8_t* src_argb,
   asm volatile(
 
       "vmovdqa     %6,%%ymm3                     \n"
-      "vbroadcastf128 %5,%%ymm4                     \n"
+      "vbroadcastf128 %5,%%ymm4                  \n"
 
       LABELALIGN
       "1:                                        \n"
diff --git a/source/scale.cc b/source/scale.cc
index 84c78711..5f0ff646 100644
--- a/source/scale.cc
+++ b/source/scale.cc
@@ -2021,7 +2021,7 @@ int I420Scale(const uint8_t* src_y,
   int src_halfheight = SUBSAMPLE(src_height, 1, 1);
   int dst_halfwidth = SUBSAMPLE(dst_width, 1, 1);
   int dst_halfheight = SUBSAMPLE(dst_height, 1, 1);
-  if (!src_y || !src_u || !src_v || src_width == 0 || src_height == 0 ||
+  if (!src_y || !src_u || !src_v || src_width <= 0 || src_height == 0 ||
       src_width > 32768 || src_height > 32768 || !dst_y || !dst_u || !dst_v ||
       dst_width <= 0 || dst_height <= 0) {
     return -1;
@@ -2058,7 +2058,7 @@ int I420Scale_16(const uint16_t* src_y,
   int src_halfheight = SUBSAMPLE(src_height, 1, 1);
   int dst_halfwidth = SUBSAMPLE(dst_width, 1, 1);
   int dst_halfheight = SUBSAMPLE(dst_height, 1, 1);
-  if (!src_y || !src_u || !src_v || src_width == 0 || src_height == 0 ||
+  if (!src_y || !src_u || !src_v || src_width <= 0 || src_height == 0 ||
       src_width > 32768 || src_height > 32768 || !dst_y || !dst_u || !dst_v ||
       dst_width <= 0 || dst_height <= 0) {
     return -1;
@@ -2094,7 +2094,7 @@ int I444Scale(const uint8_t* src_y,
               int dst_width,
               int dst_height,
               enum FilterMode filtering) {
-  if (!src_y || !src_u || !src_v || src_width == 0 || src_height == 0 ||
+  if (!src_y || !src_u || !src_v || src_width <= 0 || src_height == 0 ||
       src_width > 32768 || src_height > 32768 || !dst_y || !dst_u || !dst_v ||
       dst_width <= 0 || dst_height <= 0) {
     return -1;
@@ -2127,7 +2127,7 @@ int I444Scale_16(const uint16_t* src_y,
                  int dst_width,
                  int dst_height,
                  enum FilterMode filtering) {
-  if (!src_y || !src_u || !src_v || src_width == 0 || src_height == 0 ||
+  if (!src_y || !src_u || !src_v || src_width <= 0 || src_height == 0 ||
       src_width > 32768 || src_height > 32768 || !dst_y || !dst_u || !dst_v ||
       dst_width <= 0 || dst_height <= 0) {
     return -1;
@@ -2163,7 +2163,7 @@ int NV12Scale(const uint8_t* src_y,
   int src_halfheight = SUBSAMPLE(src_height, 1, 1);
   int dst_halfwidth = SUBSAMPLE(dst_width, 1, 1);
   int dst_halfheight = SUBSAMPLE(dst_height, 1, 1);
-  if (!src_y || !src_uv || src_width == 0 || src_height == 0 ||
+  if (!src_y || !src_uv || src_width <= 0 || src_height == 0 ||
       src_width > 32768 || src_height > 32768 || !dst_y || !dst_uv ||
       dst_width <= 0 || dst_height <= 0) {
     return -1;
diff --git a/source/scale_gcc.cc b/source/scale_gcc.cc
index d1fb7de1..f03903f0 100644
--- a/source/scale_gcc.cc
+++ b/source/scale_gcc.cc
@@ -1234,7 +1234,7 @@ void ScaleRowUp2_Linear_AVX2(const uint8_t* src_ptr,
       "vpcmpeqw    %%ymm4,%%ymm4,%%ymm4          \n"
       "vpsrlw      $15,%%ymm4,%%ymm4             \n"
       "vpsllw      $1,%%ymm4,%%ymm4              \n"  // all 2
-      "vbroadcastf128 %3,%%ymm3                     \n"
+      "vbroadcastf128 %3,%%ymm3                  \n"
 
       LABELALIGN
       "1:                                        \n"
@@ -1278,7 +1278,7 @@ void ScaleRowUp2_Bilinear_AVX2(const uint8_t* src_ptr,
       "vpcmpeqw    %%ymm6,%%ymm6,%%ymm6          \n"
       "vpsrlw      $15,%%ymm6,%%ymm6             \n"
       "vpsllw      $3,%%ymm6,%%ymm6              \n"  // all 8
-      "vbroadcastf128 %5,%%ymm7                     \n"
+      "vbroadcastf128 %5,%%ymm7                  \n"
 
       LABELALIGN
       "1:                                        \n"
@@ -1357,7 +1357,7 @@ void ScaleRowUp2_Linear_16_AVX2(const uint16_t* src_ptr,
                                 uint16_t* dst_ptr,
                                 int dst_width) {
   asm volatile(
-      "vbroadcastf128 %3,%%ymm5                     \n"
+      "vbroadcastf128 %3,%%ymm5                  \n"
       "vpcmpeqw    %%ymm4,%%ymm4,%%ymm4          \n"
       "vpsrlw      $15,%%ymm4,%%ymm4             \n"
       "vpsllw      $1,%%ymm4,%%ymm4              \n"  // all 2
@@ -1409,7 +1409,7 @@ void ScaleRowUp2_Bilinear_16_AVX2(const uint16_t* src_ptr,
                                   ptrdiff_t dst_stride,
                                   int dst_width) {
   asm volatile(
-      "vbroadcastf128 %5,%%ymm5                     \n"
+      "vbroadcastf128 %5,%%ymm5                  \n"
       "vpcmpeqw    %%ymm4,%%ymm4,%%ymm4          \n"
       "vpsrlw      $15,%%ymm4,%%ymm4             \n"
       "vpsllw      $3,%%ymm4,%%ymm4              \n"  // all 8
@@ -2123,8 +2123,8 @@ void ScaleUVRowDown2Box_AVX2(const uint8_t* src_ptr,
 }
 #endif  // HAS_SCALEUVROWDOWN2BOX_AVX2
 
-static const uvec8 kUVLinearMadd31 = {3, 1, 3, 1, 1, 3, 1, 3, 3, 1, 3,
-                                      1, 1, 3, 1, 3};
+static const uvec8 kUVLinearMadd31 = {3, 1, 3, 1, 1, 3, 1, 3,
+                                      3, 1, 3, 1, 1, 3, 1, 3};
 
 #ifdef HAS_SCALEUVROWUP2LINEAR_SSSE3
 void ScaleUVRowUp2_Linear_SSSE3(const uint8_t* src_ptr,
@@ -2259,7 +2259,7 @@ void ScaleUVRowUp2_Linear_AVX2(const uint8_t* src_ptr,
       "vpcmpeqw    %%ymm4,%%ymm4,%%ymm4          \n"
       "vpsrlw      $15,%%ymm4,%%ymm4             \n"
       "vpsllw      $1,%%ymm4,%%ymm4              \n"  // all 2
-      "vbroadcastf128 %3,%%ymm3                     \n"
+      "vbroadcastf128 %3,%%ymm3                  \n"
 
       LABELALIGN
       "1:                                        \n"
@@ -2302,7 +2302,7 @@ void ScaleUVRowUp2_Bilinear_AVX2(const uint8_t* src_ptr,
       "vpcmpeqw    %%ymm6,%%ymm6,%%ymm6          \n"
       "vpsrlw      $15,%%ymm6,%%ymm6             \n"
       "vpsllw      $3,%%ymm6,%%ymm6              \n"  // all 8
-      "vbroadcastf128 %5,%%ymm7                     \n"
+      "vbroadcastf128 %5,%%ymm7                  \n"
 
       LABELALIGN
       "1:                                        \n"
@@ -2416,7 +2416,6 @@ void ScaleUVRowUp2_Linear_16_SSE2(const uint16_t* src_ptr,
       "lea         0x10(%1),%1                   \n"  // 2 uv to 4 uv
       "sub         $0x4,%2                       \n"
       "jg          1b                            \n"
-      "vzeroupper                                \n"
       : "+r"(src_ptr),   // %0
         "+r"(dst_ptr),   // %1
         "+r"(dst_width)  // %2
diff --git a/source/scale_neon.cc b/source/scale_neon.cc
index 14d8fcd8..41dba3e8 100644
--- a/source/scale_neon.cc
+++ b/source/scale_neon.cc
@@ -825,7 +825,8 @@ void ScaleUVRowUp2_Linear_16_NEON(const uint16_t* src_ptr,
         "+r"(dst_width),  // %2
         "+r"(src_temp)    // %3
       :
-      : "memory", "cc", "q0", "q1", "q2", "q3", "q4", "q5", "d30"  // Clobber List
+      : "memory", "cc", "q0", "q1", "q2", "q3", "q4", "q5",
+        "d30"  // Clobber List
   );
 }
 
diff --git a/source/scale_neon64.cc b/source/scale_neon64.cc
index 0ac4e2ea..22fedcb5 100644
--- a/source/scale_neon64.cc
+++ b/source/scale_neon64.cc
@@ -852,7 +852,8 @@ void ScaleUVRowUp2_Linear_16_NEON(const uint16_t* src_ptr,
         "+r"(dst_ptr),   // %2
         "+r"(dst_width)  // %3
       :
-      : "memory", "cc", "v0", "v1", "v2", "v3", "v4", "v5", "v31"  // Clobber List
+      : "memory", "cc", "v0", "v1", "v2", "v3", "v4", "v5",
+        "v31"  // Clobber List
   );
 }
 
diff --git a/source/scale_uv.cc b/source/scale_uv.cc
index 7baeae6d..7b977912 100644
--- a/source/scale_uv.cc
+++ b/source/scale_uv.cc
@@ -934,9 +934,9 @@ static void ScaleUVSimple(int src_width,
 // Copy UV with optional flipping
 #if HAS_UVCOPY
 static int UVCopy(const uint8_t* src_UV,
-                  int src_stride_UV,
+                  int src_stride_uv,
                   uint8_t* dst_UV,
-                  int dst_stride_UV,
+                  int dst_stride_uv,
                   int width,
                   int height) {
   if (!src_UV || !dst_UV || width <= 0 || height == 0) {
@@ -945,18 +945,18 @@ static int UVCopy(const uint8_t* src_UV,
   // Negative height means invert the image.
   if (height < 0) {
     height = -height;
-    src_UV = src_UV + (height - 1) * src_stride_UV;
-    src_stride_UV = -src_stride_UV;
+    src_UV = src_UV + (height - 1) * src_stride_uv;
+    src_stride_uv = -src_stride_uv;
   }
 
-  CopyPlane(src_UV, src_stride_UV, dst_UV, dst_stride_UV, width * 2, height);
+  CopyPlane(src_UV, src_stride_uv, dst_UV, dst_stride_uv, width * 2, height);
   return 0;
 }
 
 static int UVCopy_16(const uint16_t* src_UV,
-                     int src_stride_UV,
+                     int src_stride_uv,
                      uint16_t* dst_UV,
-                     int dst_stride_UV,
+                     int dst_stride_uv,
                      int width,
                      int height) {
   if (!src_UV || !dst_UV || width <= 0 || height == 0) {
@@ -965,11 +965,11 @@ static int UVCopy_16(const uint16_t* src_UV,
   // Negative height means invert the image.
   if (height < 0) {
     height = -height;
-    src_UV = src_UV + (height - 1) * src_stride_UV;
-    src_stride_UV = -src_stride_UV;
+    src_UV = src_UV + (height - 1) * src_stride_uv;
+    src_stride_uv = -src_stride_uv;
   }
 
-  CopyPlane_16(src_UV, src_stride_UV, dst_UV, dst_stride_UV, width * 2, height);
+  CopyPlane_16(src_UV, src_stride_uv, dst_UV, dst_stride_uv, width * 2, height);
   return 0;
 }
 #endif  // HAS_UVCOPY
@@ -1117,7 +1117,7 @@ int UVScale(const uint8_t* src_uv,
             int dst_width,
             int dst_height,
             enum FilterMode filtering) {
-  if (!src_uv || src_width == 0 || src_height == 0 || src_width > 32768 ||
+  if (!src_uv || src_width <= 0 || src_height == 0 || src_width > 32768 ||
       src_height > 32768 || !dst_uv || dst_width <= 0 || dst_height <= 0) {
     return -1;
   }
@@ -1126,7 +1126,7 @@ int UVScale(const uint8_t* src_uv,
   return 0;
 }
 
-// Scale an 16 bit UV image.
+// Scale a 16 bit UV image.
 // This function is currently incomplete, it can't handle all cases.
 LIBYUV_API
 int UVScale_16(const uint16_t* src_uv,
@@ -1140,7 +1140,7 @@ int UVScale_16(const uint16_t* src_uv,
                enum FilterMode filtering) {
   int dy = 0;
 
-  if (!src_uv || src_width == 0 || src_height == 0 || src_width > 32768 ||
+  if (!src_uv || src_width <= 0 || src_height == 0 || src_width > 32768 ||
       src_height > 32768 || !dst_uv || dst_width <= 0 || dst_height <= 0) {
     return -1;
   }
diff --git a/unit_test/convert_test.cc b/unit_test/convert_test.cc
index 2922fc40..50593160 100644
--- a/unit_test/convert_test.cc
+++ b/unit_test/convert_test.cc
@@ -55,13 +55,13 @@ namespace libyuv {
     static_assert(SRC_BPC == 1 || SRC_BPC == 2, "SRC BPC unsupported");       \
     static_assert(DST_BPC == 1 || DST_BPC == 2, "DST BPC unsupported");       \
     static_assert(SRC_SUBSAMP_X == 1 || SRC_SUBSAMP_X == 2,                   \
-                  "DST SRC_SUBSAMP_X unsupported");                           \
+                  "SRC_SUBSAMP_X unsupported");                           \
     static_assert(SRC_SUBSAMP_Y == 1 || SRC_SUBSAMP_Y == 2,                   \
-                  "DST SRC_SUBSAMP_Y unsupported");                           \
+                  "SRC_SUBSAMP_Y unsupported");                           \
     static_assert(DST_SUBSAMP_X == 1 || DST_SUBSAMP_X == 2,                   \
-                  "DST DST_SUBSAMP_X unsupported");                           \
+                  "DST_SUBSAMP_X unsupported");                           \
     static_assert(DST_SUBSAMP_Y == 1 || DST_SUBSAMP_Y == 2,                   \
-                  "DST DST_SUBSAMP_Y unsupported");                           \
+                  "DST_SUBSAMP_Y unsupported");                           \
     const int kWidth = ((W1280) > 0) ? (W1280) : 1;                           \
     const int kHeight = benchmark_height_;                                    \
     const int kSrcHalfWidth = SUBSAMPLE(kWidth, SRC_SUBSAMP_X);               \
@@ -385,13 +385,13 @@ TESTPLANARTOBP(I400, 2, 2, NV21, 2, 2)
     static_assert(SRC_BPC == 1 || SRC_BPC == 2, "SRC BPC unsupported");        \
     static_assert(DST_BPC == 1 || DST_BPC == 2, "DST BPC unsupported");        \
     static_assert(SRC_SUBSAMP_X == 1 || SRC_SUBSAMP_X == 2,                    \
-                  "DST SRC_SUBSAMP_X unsupported");                            \
+                  "SRC_SUBSAMP_X unsupported");                            \
     static_assert(SRC_SUBSAMP_Y == 1 || SRC_SUBSAMP_Y == 2,                    \
-                  "DST SRC_SUBSAMP_Y unsupported");                            \
+                  "SRC_SUBSAMP_Y unsupported");                            \
     static_assert(DST_SUBSAMP_X == 1 || DST_SUBSAMP_X == 2,                    \
-                  "DST DST_SUBSAMP_X unsupported");                            \
+                  "DST_SUBSAMP_X unsupported");                            \
     static_assert(DST_SUBSAMP_Y == 1 || DST_SUBSAMP_Y == 2,                    \
-                  "DST DST_SUBSAMP_Y unsupported");                            \
+                  "DST_SUBSAMP_Y unsupported");                            \
     const int kWidth = ((W1280) > 0) ? (W1280) : 1;                            \
     const int kHeight = benchmark_height_;                                     \
     const int kSrcHalfWidth = SUBSAMPLE(kWidth, SRC_SUBSAMP_X);                \
@@ -423,17 +423,17 @@ TESTPLANARTOBP(I400, 2, 2, NV21, 2, 2)
     memset(dst_uv_opt, 102, 2 * kDstHalfWidth * kDstHalfHeight * DST_BPC);     \
     MaskCpuFlags(disable_cpu_flags_);                                          \
     SRC_FMT_PLANAR##To##FMT_PLANAR(                                            \
-        src_y_p, kWidth, src_uv_p, 2 * kSrcHalfWidth,                \
+        src_y_p, kWidth, src_uv_p, 2 * kSrcHalfWidth,                          \
         DOY ? reinterpret_cast<DST_T*>(dst_y_c) : NULL, kWidth,                \
-        reinterpret_cast<DST_T*>(dst_uv_c), 2 * kDstHalfWidth,       \
-        kWidth, NEG kHeight);                                                  \
+        reinterpret_cast<DST_T*>(dst_uv_c), 2 * kDstHalfWidth, kWidth,         \
+        NEG kHeight);                                                          \
     MaskCpuFlags(benchmark_cpu_info_);                                         \
     for (int i = 0; i < benchmark_iterations_; ++i) {                          \
       SRC_FMT_PLANAR##To##FMT_PLANAR(                                          \
-          src_y_p, kWidth, src_uv_p, 2 * kSrcHalfWidth,              \
+          src_y_p, kWidth, src_uv_p, 2 * kSrcHalfWidth,                        \
           DOY ? reinterpret_cast<DST_T*>(dst_y_opt) : NULL, kWidth,            \
-          reinterpret_cast<DST_T*>(dst_uv_opt), 2 * kDstHalfWidth,   \
-          kWidth, NEG kHeight);                                                \
+          reinterpret_cast<DST_T*>(dst_uv_opt), 2 * kDstHalfWidth, kWidth,     \
+          NEG kHeight);                                                        \
     }                                                                          \
     if (DOY) {                                                                 \
       for (int i = 0; i < kHeight; ++i) {                                      \
@@ -483,7 +483,7 @@ TESTBIPLANARTOBP(NV21, uint8_t, 1, 2, 2, NV12, uint8_t, 1, 2, 2, 8)
 TESTBIPLANARTOBP(NV12, uint8_t, 1, 2, 2, NV12Mirror, uint8_t, 1, 2, 2, 8)
 TESTBIPLANARTOBP(NV12, uint8_t, 1, 2, 2, NV24, uint8_t, 1, 1, 1, 8)
 TESTBIPLANARTOBP(NV16, uint8_t, 1, 2, 1, NV24, uint8_t, 1, 1, 1, 8)
-// These formats put data at high bits, so test on full 16bit range.
+// These formats put data in high bits, so test on full 16bit range.
 TESTBIPLANARTOBP(P010, uint16_t, 2, 2, 2, P410, uint16_t, 2, 1, 1, 16)
 TESTBIPLANARTOBP(P210, uint16_t, 2, 2, 1, P410, uint16_t, 2, 1, 1, 16)
 TESTBIPLANARTOBP(P012, uint16_t, 2, 2, 2, P412, uint16_t, 2, 1, 1, 16)
diff --git a/util/yuvconstants.cc b/util/yuvconstants.cc
new file mode 100644
index 00000000..be900878
--- /dev/null
+++ b/util/yuvconstants.cc
@@ -0,0 +1,106 @@
+/*
+ *  Copyright 2021 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.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// This utility computes values needed to generate yuvconstants based on
+// white point values.
+// The yuv formulas are tuned for 8 bit YUV channels.
+
+// See Also
+// https://mymusing.co/bt601-yuv-to-rgb-conversion-color/
+
+// BT.709 full range YUV to RGB reference
+//  R = Y               + V * 1.5748
+//  G = Y - U * 0.18732 - V * 0.46812
+//  B = Y + U * 1.8556
+//  KR = 0.2126
+//  KB = 0.0722
+
+// // Y contribution to R,G,B.  Scale and bias.
+// #define YG 16320 /* round(1.000 * 64 * 256 * 256 / 257) */
+// #define YB 32    /* 64 / 2 */
+//
+// // U and V contributions to R,G,B.
+// #define UB 113 /* round(1.77200 * 64) */
+// #define UG 22  /* round(0.34414 * 64) */
+// #define VG 46  /* round(0.71414 * 64) */
+// #define VR 90  /* round(1.40200 * 64) */
+//
+// // Bias values to round, and subtract 128 from U and V.
+// #define BB (-UB * 128 + YB)
+// #define BG (UG * 128 + VG * 128 + YB)
+// #define BR (-VR * 128 + YB)
+
+#define round(v) ((int)(v + 0.5))
+
+int main(int argc, const char* argv[]) {
+  if (argc < 2) {
+    printf("yuvconstants Kr Kb\n");
+    printf("  MC BT          KR = 0.2126; KB = 0.0722\n");
+    printf("  1  BT.709      KR = 0.2126; KB = 0.0722\n");
+    printf("  4  FCC         KR = 0.30;   KB = 0.11\n");
+    printf("  6  BT.601      KR = 0.299;  KB = 0.114\n");
+    printf("  7  SMPTE 240M  KR = 0.212;  KB = 0.087\n");
+    printf("  9  BT.2020     KR = 0.2627; KB = 0.0593\n");
+    return -1;
+  }
+  float kr = atof(argv[1]);
+  float kb = atof(argv[2]);
+  float kg = 1 - kr - kb;
+
+  float vr = 2 * (1 - kr);
+  float ug = 2 * ((1 - kb) * kb / kg);
+  float vg = 2 * ((1 - kr) * kr / kg);
+  float ub = 2 * (1 - kb);
+
+  printf("Full range\n");
+  printf("R = Y                + V * %5f\n", vr);
+  printf("G = Y - U * %6f - V * %6f\n", ug, vg);
+  printf("B = Y + U * %5f\n", ub);
+
+  printf("KR = %4f; ", kr);
+  printf("KB = %4f\n", kb);
+  // printf("KG = %4f\n", kg);
+  // #define YG 16320 /* round(1.000 * 64 * 256 * 256 / 257) */
+  // #define YB 32    /* 64 / 2 */
+  //
+  // // U and V contributions to R,G,B.
+
+  printf("UB %-3d /* round(%f * 64 = %f) */\n", round(ub * 64), ub, ub * 64);
+  printf("UG %-3d /* round(%f * 64 = %f) */\n", round(ug * 64), ug, ug * 64);
+  printf("VG %-3d /* round(%f * 64 = %f) */\n", round(vg * 64), vg, vg * 64);
+  printf("VR %-3d /* round(%f * 64 = %f) */\n", round(vr * 64), vr, vr * 64);
+
+  vr = 255.f / 224.f * 2 * (1 - kr);
+  ug = 255.f / 224.f * 2 * ((1 - kb) * kb / kg);
+  vg = 255.f / 224.f * 2 * ((1 - kr) * kr / kg);
+  ub = 255.f / 224.f * 2 * (1 - kb);
+
+  printf("\nLimited range\n");
+  printf("R = (Y - 16) * 1.164                + V * %5f\n", vr);
+  printf("G = (Y - 16) * 1.164 - U * %6f - V * %6f\n", ug, vg);
+  printf("B = (Y - 16) * 1.164 + U * %5f\n", ub);
+
+  // printf("KG = %4f\n", kg);
+  // #define YG 16320 /* round(1.000 * 64 * 256 * 256 / 257) */
+  // #define YB 32    /* 64 / 2 */
+  //
+  // // U and V contributions to R,G,B.
+
+  printf("UB %-3d /* round(%f * 64 = %f) */\n", round(ub * 64), ub, ub * 64);
+  printf("UG %-3d /* round(%f * 64 = %f) */\n", round(ug * 64), ug, ug * 64);
+  printf("VG %-3d /* round(%f * 64 = %f) */\n", round(vg * 64), vg, vg * 64);
+  printf("VR %-3d /* round(%f * 64 = %f) */\n", round(vr * 64), vr, vr * 64);
+
+  return 0;
+}