Index: webrtc/base/exp_filter.cc |
diff --git a/webrtc/base/exp_filter.cc b/webrtc/base/exp_filter.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..9529480061aee23c62bcb28c94d7f63bcf6864b2 |
--- /dev/null |
+++ b/webrtc/base/exp_filter.cc |
@@ -0,0 +1,43 @@ |
+/* |
+ * Copyright (c) 2011 The WebRTC 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 "webrtc/base/exp_filter.h" |
+ |
+#include <math.h> |
+ |
+namespace rtc { |
+ |
+const float ExpFilter::kValueUndefined = -1.0f; |
+ |
+void ExpFilter::Reset(float alpha) { |
+ alpha_ = alpha; |
+ filtered_ = kValueUndefined; |
+} |
+ |
+float ExpFilter::Apply(float exp, float sample) { |
+ if (filtered_ == kValueUndefined) { |
+ // Initialize filtered value. |
+ filtered_ = sample; |
+ } else if (exp == 1.0) { |
+ filtered_ = alpha_ * filtered_ + (1 - alpha_) * sample; |
+ } else { |
+ float alpha = pow(alpha_, exp); |
+ filtered_ = alpha * filtered_ + (1 - alpha) * sample; |
+ } |
+ if (max_ != kValueUndefined && filtered_ > max_) { |
+ filtered_ = max_; |
+ } |
+ return filtered_; |
+} |
+ |
+void ExpFilter::UpdateBase(float alpha) { |
+ alpha_ = alpha; |
+} |
+} // namespace rtc |