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diff --git a/src/frame_buffer_utils.h b/src/frame_buffer_utils.h
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+/*
+ * Copyright 2020 The libgav1 Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LIBGAV1_SRC_FRAME_BUFFER_UTILS_H_
+#define LIBGAV1_SRC_FRAME_BUFFER_UTILS_H_
+
+#include <cassert>
+#include <cstdint>
+
+#include "src/gav1/decoder_buffer.h"
+
+namespace libgav1 {
+
+// The following table is from Section 6.4.2 of the spec.
+//
+// subsampling_x  subsampling_y  mono_chrome  Description
+// -----------------------------------------------------------
+// 0              0              0            YUV 4:4:4
+// 1              0              0            YUV 4:2:2
+// 1              1              0            YUV 4:2:0
+// 1              1              1            Monochrome 4:0:0
+
+inline Libgav1ImageFormat ComposeImageFormat(bool is_monochrome,
+                                             int8_t subsampling_x,
+                                             int8_t subsampling_y) {
+  Libgav1ImageFormat image_format;
+  if (subsampling_x == 0) {
+    assert(subsampling_y == 0 && !is_monochrome);
+    image_format = kLibgav1ImageFormatYuv444;
+  } else if (subsampling_y == 0) {
+    assert(!is_monochrome);
+    image_format = kLibgav1ImageFormatYuv422;
+  } else if (!is_monochrome) {
+    image_format = kLibgav1ImageFormatYuv420;
+  } else {
+    image_format = kLibgav1ImageFormatMonochrome400;
+  }
+  return image_format;
+}
+
+inline void DecomposeImageFormat(Libgav1ImageFormat image_format,
+                                 bool* is_monochrome, int8_t* subsampling_x,
+                                 int8_t* subsampling_y) {
+  *is_monochrome = false;
+  *subsampling_x = 1;
+  *subsampling_y = 1;
+  switch (image_format) {
+    case kLibgav1ImageFormatYuv420:
+      break;
+    case kLibgav1ImageFormatYuv422:
+      *subsampling_y = 0;
+      break;
+    case kLibgav1ImageFormatYuv444:
+      *subsampling_x = *subsampling_y = 0;
+      break;
+    default:
+      assert(image_format == kLibgav1ImageFormatMonochrome400);
+      *is_monochrome = true;
+      break;
+  }
+}
+
+}  // namespace libgav1
+
+#endif  // LIBGAV1_SRC_FRAME_BUFFER_UTILS_H_