Move HalfFloatMaker to media

media/video/half_float_maker_lib_yuv.cc

+// Copyright (c) 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/video/half_float_maker_lib_yuv.h"
+#include "third_party/libyuv/include/libyuv.h"
+
+namespace media {
+
+HalfFloatMaker_libyuv::HalfFloatMaker_libyuv(int bits_per_channel) {
+  int max_value = (1 << bits_per_channel) - 1;
+  // For less than 15 bits, we can give libyuv a multiplier of
+  // 1.0, which is faster on some platforms. If bits is 16 or larger,
+  // a multiplier of 1.0 would cause overflows. However, a multiplier
+  // of 1/max_value would cause subnormal floats, which perform
+  // very poorly on some platforms.
+  if (bits_per_channel <= 15) {
+    libyuv_multiplier_ = 1.0f;
+  } else {
+    // This multiplier makes sure that we avoid subnormal values.
+    libyuv_multiplier_ = 1.0f / 4096.0f;
+  }
+  resource_multiplier_ = 1.0f / libyuv_multiplier_ / max_value;
+}
+
+float HalfFloatMaker_libyuv::Offset() const {
+  return 0.5;
+}
+
+float HalfFloatMaker_libyuv::Multiplier() const {
+  return resource_multiplier_;
+}
+
+void HalfFloatMaker_libyuv::MakeHalfFloats(const uint16_t* src,
+                                           size_t num,
+                                           uint16_t* dst) {
+  // Source and dest stride can be zero since we're only copying
+  // one row at a time.
+  int stride = 0;
+  int rows = 1;
+  libyuv::HalfFloatPlane(src, stride, dst, stride, libyuv_multiplier_, num,
+                         rows);
+}
+
+}  // namespace media