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diff --git a/third_party/libwebrtc/modules/audio_processing/vad/standalone_vad.h b/third_party/libwebrtc/modules/audio_processing/vad/standalone_vad.h
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+/*
+ *  Copyright (c) 2012 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 MODULES_AUDIO_PROCESSING_AGC_STANDALONE_VAD_H_
+#define MODULES_AUDIO_PROCESSING_AGC_STANDALONE_VAD_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "common_audio/vad/include/webrtc_vad.h"
+#include "modules/audio_processing/vad/common.h"
+
+namespace webrtc {
+
+class StandaloneVad {
+ public:
+  static StandaloneVad* Create();
+  ~StandaloneVad();
+
+  // Outputs
+  //   p: a buffer where probabilities are written to.
+  //   length_p: number of elements of `p`.
+  //
+  // return value:
+  //    -1: if no audio is stored or VAD returns error.
+  //     0: in success.
+  // In case of error the content of `activity` is unchanged.
+  //
+  // Note that due to a high false-positive (VAD decision is active while the
+  // processed audio is just background noise) rate, stand-alone VAD is used as
+  // a one-sided indicator. The activity probability is 0.5 if the frame is
+  // classified as active, and the probability is 0.01 if the audio is
+  // classified as passive. In this way, when probabilities are combined, the
+  // effect of the stand-alone VAD is neutral if the input is classified as
+  // active.
+  int GetActivity(double* p, size_t length_p);
+
+  // Expecting 10 ms of 16 kHz audio to be pushed in.
+  int AddAudio(const int16_t* data, size_t length);
+
+  // Set aggressiveness of VAD, 0 is the least aggressive and 3 is the most
+  // aggressive mode. Returns -1 if the input is less than 0 or larger than 3,
+  // otherwise 0 is returned.
+  int set_mode(int mode);
+  // Get the agressiveness of the current VAD.
+  int mode() const { return mode_; }
+
+ private:
+  explicit StandaloneVad(VadInst* vad);
+
+  static const size_t kMaxNum10msFrames = 3;
+
+  // TODO(turajs): Is there a way to use scoped-pointer here?
+  VadInst* vad_;
+  int16_t buffer_[kMaxNum10msFrames * kLength10Ms];
+  size_t index_;
+  int mode_;
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_AGC_STANDALONE_VAD_H_