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      1 /*
      2  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_MODULES_AUDIO_CODING_NETEQ_DELAY_PEAK_DETECTOR_H_
     12 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_DELAY_PEAK_DETECTOR_H_
     13 
     14 #include <string.h>  // size_t
     15 
     16 #include <list>
     17 
     18 #include "webrtc/base/constructormagic.h"
     19 
     20 namespace webrtc {
     21 
     22 class DelayPeakDetector {
     23  public:
     24   DelayPeakDetector();
     25   virtual ~DelayPeakDetector() {}
     26   virtual void Reset();
     27 
     28   // Notifies the DelayPeakDetector of how much audio data is carried in each
     29   // packet.
     30   virtual void SetPacketAudioLength(int length_ms);
     31 
     32   // Returns true if peak-mode is active. That is, delay peaks were observed
     33   // recently.
     34   virtual bool peak_found() { return peak_found_; }
     35 
     36   // Calculates and returns the maximum delay peak height. Returns -1 if no
     37   // delay peaks have been observed recently. The unit is number of packets.
     38   virtual int MaxPeakHeight() const;
     39 
     40   // Calculates and returns the maximum delay peak distance in ms.
     41   // Returns -1 if no delay peaks have been observed recently.
     42   virtual int MaxPeakPeriod() const;
     43 
     44   // Updates the DelayPeakDetector with a new inter-arrival time (in packets)
     45   // and the current target buffer level (needed to decide if a peak is observed
     46   // or not). Returns true if peak-mode is active, false if not.
     47   virtual bool Update(int inter_arrival_time, int target_level);
     48 
     49   // Increments the |peak_period_counter_ms_| with |inc_ms|. Only increments
     50   // the counter if it is non-negative. A negative denotes that no peak has
     51   // been observed.
     52   virtual void IncrementCounter(int inc_ms);
     53 
     54  private:
     55   static const size_t kMaxNumPeaks = 8;
     56   static const size_t kMinPeaksToTrigger = 2;
     57   static const int kPeakHeightMs = 78;
     58   static const int kMaxPeakPeriodMs = 10000;
     59 
     60   typedef struct {
     61     int period_ms;
     62     int peak_height_packets;
     63   } Peak;
     64 
     65   bool CheckPeakConditions();
     66 
     67   std::list<Peak> peak_history_;
     68   bool peak_found_;
     69   int peak_detection_threshold_;
     70   int peak_period_counter_ms_;
     71 
     72   DISALLOW_COPY_AND_ASSIGN(DelayPeakDetector);
     73 };
     74 
     75 }  // namespace webrtc
     76 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_DELAY_PEAK_DETECTOR_H_
     77