Index: media/video/half_float_maker_lib_yuv.cc |
diff --git a/media/video/half_float_maker_lib_yuv.cc b/media/video/half_float_maker_lib_yuv.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..dc3f90047689e9455c20324068b34225e0f9068d |
--- /dev/null |
+++ b/media/video/half_float_maker_lib_yuv.cc |
@@ -0,0 +1,45 @@ |
+// 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 |