silencedetect.h

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/*
 * silencedetect.h
 *
 * Open Phone Abstraction Library (OPAL)
 * Formally known as the Open H323 project.
 *
 * Copyright (c) 2004 Post Increment
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is Open Phone Abstraction Library.
 *
 * The Initial Developer of the Original Code is Equivalence Pty. Ltd.
 *
 * Contributor(s): ______________________________________.
 */

#ifndef OPAL_CODEC_SILENCEDETECT_H
#define OPAL_CODEC_SILENCEDETECT_H

#ifdef P_USE_PRAGMA
#pragma interface
#endif

#include <opal_config.h>
#include <rtp/rtp.h>



class OpalSilenceDetector : public PObject
{
    PCLASSINFO(OpalSilenceDetector, PObject);
  public:
    P_DECLARE_STREAMABLE_ENUM(Modes,
      NoSilenceDetection,
      FixedSilenceDetection,
      AdaptiveSilenceDetection
    );
    typedef Modes Mode; // Backward compatibility

    struct Params {
      Params(
        Modes mode = AdaptiveSilenceDetection, 
        unsigned threshold = 0,               
        unsigned signalDeadband = 10,         
        unsigned silenceDeadband = 400,       
        unsigned adaptivePeriod = 600         
      )
        : m_mode(mode),
          m_threshold(threshold),
          m_signalDeadband(signalDeadband),
          m_silenceDeadband(silenceDeadband),
          m_adaptivePeriod(adaptivePeriod)
        { }

      PString AsString() const;
      void FromString(const PString & str);

      Modes    m_mode;             
      unsigned m_threshold;        
      unsigned m_signalDeadband;   
      unsigned m_silenceDeadband;  
      unsigned m_adaptivePeriod;   
    };

    OpalSilenceDetector(
      const Params & newParam 
    );

    const PNotifier & GetReceiveHandler() const { return m_receiveHandler; }

    void SetParameters(
      const Params & params,  
      const int clockRate = 0 
    );

    void GetParameters(
      Params & params
    );

    void SetClockRate(
      unsigned clockRate     
    );

    unsigned GetClockRate() const { return m_clockRate; }

    enum Result
    {
      IsSilent,
      VoiceActivated,
      VoiceActive
    };

    Result GetResult(
      unsigned * currentThreshold = NULL,
      unsigned * currentLevel = NULL
    ) const;

    Result Detect(
      const BYTE * audioPtr,
      PINDEX audioLen,
      unsigned timestamp
    );

    virtual unsigned GetAverageSignalLevel(
      const BYTE * buffer,  
      PINDEX size           
    ) = 0;

    static unsigned GetAverageSignalLevelPCM16(
      const BYTE * buffer,  
      PINDEX size,          
      bool asPercentage     
    );

  private:
    void AdaptiveReset();

  protected:
    PDECLARE_NOTIFIER(RTP_DataFrame, OpalSilenceDetector, ReceivedPacket);

    PNotifier m_receiveHandler;

    Mode     m_mode;
    unsigned m_signalDeadband;        // #samples of signal needed
    unsigned m_silenceDeadband;       // #samples of silence needed
    unsigned m_adaptivePeriod;        // #samples window for adaptive threshold
    unsigned m_clockRate;             // audio sampling rate

    unsigned m_lastTimestamp;         // Last timestamp received
    unsigned m_receivedTime;          // Signal/Silence duration received so far.
    unsigned m_levelThreshold;        // Threshold level for silence/signal
    unsigned m_signalMinimum;         // Minimum of frames above threshold
    unsigned m_silenceMaximum;        // Maximum of frames below threshold
    unsigned m_signalReceivedTime;    // Duration of signal received
    unsigned m_silenceReceivedTime;   // Duration of silence received
    unsigned m_lastSignalLevel;       // Energy level from last data frame
    Result   m_lastResult;            // What it says
    PDECLARE_MUTEX(m_inUse);          // Protects values to allow change while running
};


class OpalPCM16SilenceDetector : public OpalSilenceDetector
{
    PCLASSINFO(OpalPCM16SilenceDetector, OpalSilenceDetector);
  public:
    OpalPCM16SilenceDetector(
      const Params & newParam 
    ) : OpalSilenceDetector(newParam) { }

    virtual unsigned GetAverageSignalLevel(
      const BYTE * buffer,  
      PINDEX size           
    );
};


extern ostream & operator<<(ostream & strm, OpalSilenceDetector::Mode mode);


#endif // OPAL_CODEC_SILENCEDETECT_H