Index: webrtc/base/exp_filter.h |
diff --git a/webrtc/base/exp_filter.h b/webrtc/base/exp_filter.h |
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+/* |
+ * 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. |
+ */ |
+ |
+#ifndef WEBRTC_BASE_EXP_FILTER_H_ |
+#define WEBRTC_BASE_EXP_FILTER_H_ |
+ |
+namespace rtc { |
+ |
+// This class can be used, for example, for smoothing the result of bandwidth |
+// estimation and packet loss estimation. |
+ |
+class ExpFilter { |
+ public: |
+ static const float kValueUndefined; |
+ |
+ explicit ExpFilter(float alpha, float max = kValueUndefined) |
+ : max_(max) { |
+ Reset(alpha); |
+ } |
+ |
+ // Resets the filter to its initial state, and resets filter factor base to |
+ // the given value |alpha|. |
+ void Reset(float alpha); |
+ |
+ // Applies the filter with a given exponent on the provided sample: |
+ // y(k) = min(alpha_^ exp * y(k-1) + (1 - alpha_^ exp) * sample, max_). |
+ float Apply(float exp, float sample); |
+ |
+ // Returns current filtered value. |
+ float filtered() const { return filtered_; } |
+ |
+ // Changes the filter factor base to the given value |alpha|. |
+ void UpdateBase(float alpha); |
+ |
+ private: |
+ float alpha_; // Filter factor base. |
+ float filtered_; // Current filter output. |
+ const float max_; |
+}; |
+} // namespace rtc |
+ |
+#endif // WEBRTC_BASE_EXP_FILTER_H_ |