include/codec/silencedetect.h

   1 /*
   2  * silencedetect.h
   3  *
   4  * Open Phone Abstraction Library (OPAL)
   5  * Formally known as the Open H323 project.
   6  *
   7  * Copyright (c) 2004 Post Increment
   8  *
   9  * The contents of this file are subject to the Mozilla Public License
  10  * Version 1.0 (the "License"); you may not use this file except in
  11  * compliance with the License. You may obtain a copy of the License at
  12  * http://www.mozilla.org/MPL/
  13  *
  14  * Software distributed under the License is distributed on an "AS IS"
  15  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  16  * the License for the specific language governing rights and limitations
  17  * under the License.
  18  *
  19  * The Original Code is Open Phone Abstraction Library.
  20  *
  21  * The Initial Developer of the Original Code is Equivalence Pty. Ltd.
  22  *
  23  * Contributor(s): ______________________________________.
  24  *
  25  * $Log$
  26  * Revision 1.4  2005/11/30 13:35:26  csoutheren
  27  * Changed tags for Doxygen
  28  *
  29  * Revision 1.3  2005/07/09 06:52:38  rjongbloed
  30  * Added print (operator<<) of silence detect mode enum.
  31  *
  32  * Revision 1.2  2004/05/24 13:39:26  rjongbloed
  33  * Fixed setting marker bit when silence suppression transitions from
  34  *   silence to signal, thanks Ted Szoczei
  35  * Added a separate structure for the silence suppression paramters to make
  36  *   it easier to set from global defaults in the manager class.
  37  *
  38  * Revision 1.1  2004/05/17 13:24:26  rjongbloed
  39  * Added silence suppression.
  40  *
  41  */
  42
  43 #ifndef __OPAL_SILENCEDETECT_H
  44 #define __OPAL_SILENCEDETECT_H
  45
  46 #ifdef P_USE_PRAGMA
  47 #pragma interface
  48 #endif
  49
  50
  51 #include <rtp/rtp.h>
  52
  53
  54 ///////////////////////////////////////////////////////////////////////////////
  55
  56 class OpalSilenceDetector : public PObject
  57 {
  58     PCLASSINFO(OpalSilenceDetector, PObject);
  59   public:
  60     enum Mode {
  61       NoSilenceDetection,
  62       FixedSilenceDetection,
  63       AdaptiveSilenceDetection,
  64       NumModes
  65     };
  66
  67     struct Params {
  68       Params(
  69         Mode mode = AdaptiveSilenceDetection, ///<  New silence detection mode
  70         unsigned threshold = 0,               ///<  Threshold value if FixedSilenceDetection
  71         unsigned signalDeadband = 80,         ///<  10 milliseconds of signal needed
  72         unsigned silenceDeadband = 3200,      ///<  400 milliseconds of silence needed
  73         unsigned adaptivePeriod = 4800        ///<  600 millisecond window for adaptive threshold
  74       )
  75         : m_mode(mode),
  76           m_threshold(threshold),
  77           m_signalDeadband(signalDeadband),
  78           m_silenceDeadband(silenceDeadband),
  79           m_adaptivePeriod(adaptivePeriod)
  80         { }
  81
  82       Mode     m_mode;             /// Silence detection mode
  83       unsigned m_threshold;        /// Threshold value if FixedSilenceDetection
  84       unsigned m_signalDeadband;   /// 10 milliseconds of signal needed
  85       unsigned m_silenceDeadband;  /// 400 milliseconds of silence needed
  86       unsigned m_adaptivePeriod;   /// 600 millisecond window for adaptive threshold
  87     };
  88
  89   /**@name Construction */
  90   //@{
  91     /**Create a new connection.
  92      */
  93     OpalSilenceDetector();
  94   //@}
  95
  96   /**@name Basic operations */
  97   //@{
  98     const PNotifier & GetReceiveHandler() const { return receiveHandler; }
  99
 100     /**Set the silence detector parameters.
 101        This enables, disables the silence detector as well as adjusting its
 102        "agression". The deadband periods are in audio samples of 8kHz.
 103       */
 104     void SetParameters(
 105       const Params & newParam ///<  New parameters for silence detector
 106     );
 107
 108     /**Get silence detection status
 109
 110        The inTalkBurst value is TRUE if packet transmission is enabled and
 111        FALSE if it is being suppressed due to silence.
 112
 113        The currentThreshold value is the value from 0 to 32767 which is used
 114        as the threshold value for 16 bit PCM data.
 115       */
 116     Mode GetStatus(
 117       BOOL * isInTalkBurst,
 118       unsigned * currentThreshold
 119     ) const;
 120
 121     /**Get the average signal level in the stream.
 122        This is called from within the silence detection algorithm to
 123        calculate the average signal level of the last data frame read from
 124        the stream.
 125
 126        The default behaviour returns UINT_MAX which indicates that the
 127        average signal has no meaning for the stream.
 128       */
 129     virtual unsigned GetAverageSignalLevel(
 130       const BYTE * buffer,  ///<  RTP payload being detected
 131       PINDEX size           ///<  Size of payload buffer
 132     ) = 0;
 133
 134   protected:
 135     PDECLARE_NOTIFIER(RTP_DataFrame, OpalSilenceDetector, ReceivedPacket);
 136
 137     PNotifier receiveHandler;
 138
 139     Params param;
 140
 141     BOOL     inTalkBurst;           // Currently sending RTP data
 142     unsigned lastTimestamp;         // Last timestamp received
 143     unsigned receivedTime;          // Signal/Silence duration received so far.
 144     unsigned levelThreshold;        // Threshold level for silence/signal
 145     unsigned signalMinimum;         // Minimum of frames above threshold
 146     unsigned silenceMaximum;        // Maximum of frames below threshold
 147     unsigned signalReceivedTime;    // Duration of signal received
 148     unsigned silenceReceivedTime;   // Duration of silence received
 149 };
 150
 151
 152 class OpalPCM16SilenceDetector : public OpalSilenceDetector
 153 {
 154     PCLASSINFO(OpalPCM16SilenceDetector, OpalSilenceDetector);
 155   public:
 156   /**@name Overrides from OpalSilenceDetector */
 157   //@{
 158     /**Get the average signal level in the stream.
 159        This is called from within the silence detection algorithm to
 160        calculate the average signal level of the last data frame read from
 161        the stream.
 162
 163        The default behaviour returns UINT_MAX which indicates that the
 164        average signal has no meaning for the stream.
 165       */
 166     virtual unsigned GetAverageSignalLevel(
 167       const BYTE * buffer,  ///<  RTP payload being detected
 168       PINDEX size           ///<  Size of payload buffer
 169     );
 170   //@}
 171 };
 172
 173
 174 extern ostream & operator<<(ostream & strm, OpalSilenceDetector::Mode mode);
 175
 176
 177 #endif // __OPAL_SILENCEDETECT_H
 178
 179
 180 /////////////////////////////////////////////////////////////////////////////