dtmf.h

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/*
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@FreeBSD.org> wrote this file.  As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 *
 * Extract DTMF signals from 16 bit PCM audio
 *
 * Originally written by Poul-Henning Kamp <phk@freebsd.org>
 * Made into a C++ class by Roger Hardiman <roger@freebsd.org>, January 2002
 *
 * $Revision: 24177 $
 * $Author: rjongbloed $
 * $Date: 2010-04-05 21:52:04 +1000 (Mon, 05 Apr 2010) $
 */
 
#ifndef PTLIB_DTMF_H
#define PTLIB_DTMF_H

#if P_DTMF

#ifdef P_USE_PRAGMA
#pragma interface
#endif


class PDTMFDecoder : public PObject
{
  PCLASSINFO(PDTMFDecoder, PObject)

  public:
    enum {
      DetectSamples = 520,
      DetectTime = DetectSamples/8  // Milliseconds
    };

    PDTMFDecoder();
    PString Decode(const short * sampleData, PINDEX numSamples, unsigned mult = 1, unsigned div = 1);

  protected:
    enum {
      NumTones = 10
    };

    // key lookup table (initialised once)
    char key[256];

    // frequency table (initialised once)
    int p1[NumTones];

    // variables to be retained on each cycle of the decode function
    int h[NumTones], k[NumTones], y[NumTones];
    int sampleCount, tonesDetected, inputAmplitude;
};


class PTones : public PShortArray
{
  PCLASSINFO(PTones, PShortArray)

  public:
    enum {
      MaxVolume = 100,
      DefaultSampleRate = 8000,
      MinFrequency = 30,
      MinModulation = 5,
      SineScale = 1000
    };

    PTones(
      unsigned masterVolume = MaxVolume,      
      unsigned sampleRate = DefaultSampleRate 
    );

    PTones(
      const PString & descriptor,             
      unsigned masterVolume = MaxVolume,      
      unsigned sampleRate = DefaultSampleRate 
    );

    bool Generate(
      const PString & descriptor    
    );

    bool Generate(
      char operation,             
      unsigned frequency1,        
      unsigned frequency2,        
      unsigned milliseconds,      
      unsigned volume = MaxVolume 
    );

  protected:
    void Construct();

    bool Juxtapose(unsigned frequency1, unsigned frequency2, unsigned milliseconds, unsigned volume);
    bool Modulate (unsigned frequency, unsigned modulate, unsigned milliseconds, unsigned volume);
    bool PureTone (unsigned frequency, unsigned milliseconds, unsigned volume);
    bool Silence  (unsigned milliseconds);

    unsigned CalcSamples(unsigned milliseconds, unsigned frequency1, unsigned frequency2 = 0);

    void AddSample(int sample, unsigned volume);

    unsigned m_sampleRate;
    unsigned m_maxFrequency;
    unsigned m_masterVolume;
    char     m_lastOperation;
    unsigned m_lastFrequency1, m_lastFrequency2;
    int      m_angle1, m_angle2;
};


class PDTMFEncoder : public PTones
{
  PCLASSINFO(PDTMFEncoder, PTones)

  public:
    enum { DefaultToneLen = 100 };

    PDTMFEncoder(
        const char * dtmf = NULL,      
        unsigned milliseconds = DefaultToneLen  
    );

    PDTMFEncoder(
        char key,      
        unsigned milliseconds = DefaultToneLen  
    );    

    void AddTone(
        const char * str,              
        unsigned milliseconds = DefaultToneLen  
    );

    void AddTone(
        char ch,                       
        unsigned milliseconds = DefaultToneLen  
    );

    void AddTone(
        double frequency1,                  // primary frequency
        double frequency2 = 0,              // secondary frequency, or 0 if no secondary frequency
        unsigned milliseconds = DefaultToneLen  // length of DTMF tone in milliseconds
    );

    void GenerateRingBackTone()
    {
      Generate("440+480:2-4");
    }

    void GenerateDialTone()
    {
      Generate("350+440:1");
    }

    void GenerateBusyTone()
    {
      Generate("480+620:0.5-0.5");
    }

    char DtmfChar(
        PINDEX i    
    );
    // Overiding GetSize() screws up the SetSize()
};


#endif // P_DTMF

#endif // PTLIB_DTMF_H


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