Open Phone Abstraction Library

1
Open Phone Abstraction Library

• The many colours of OPAL

3rd August 2009Robert Jongbloed
2
Introduction

• Open
• Phone
• Abstraction
• Library

3
Many colours

• Multi-platform
• Multi-protocol
• Multi-media
• Multi-threaded
• Multi-purpose

4
Multi-platform

• Windows variants - Win2000 and up
• Windows Mobile (aka WinCE)
• Linux variants
• Embedded (cross compiled) Linux
• Mac OS X
• Solaris
• VxWorks

5
Multi-protocol

• H.323
• SIP
• IAX2
• Line Interfaces PSTN
• IVR (VXML)
• Jingle (Real Soon Now)
• User defined

6
Multi-media

• Audio - narrowband
• Audio - wideband
• Video
• Fax
• Instant Messaging
• User defined

7
Multi-threaded

• Utilises multi-core CPUs
• Thread per I/O
• Scalability issues
• Synchronisation issues
• TANSTAAFL
• C API serialisation

8
Multi-purpose

• Soft Phones
• Handsets
• Gateways
• Soft PBX
• Voice/Video Mail
• Conferencing servers (MCU)

9
History

• 1993 PWLib

10
History

• 1993 PWLib
• 1997 FireDoor

11
History

• 1993 PWLib
• 1997 FireDoor
• NetMeeting please?

12
History

• 1993 PWLib
• 1997 FireDoor
• 1998 ASN compiler

13
History

• 1993 PWLib
• 1997 FireDoor
• 1998 ASN compiler
• 1998 PhonePATCH

14
History

• 1993 PWLib
• 1997 FireDoor
• 1998 ASN compiler
• 1998 PhonePATCH
• But what about incoming calls?

15
History

• 1993 PWLib
• 1997 FireDoor
• 1998 ASN compiler
• 1998 PhonePATCH
• 1999 OpenH323

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History

• 1993 PWLib
• 1997 FireDoor
• 1998 ASN compiler
• 1998 PhonePATCH
• 1999 OpenH323
• Why Open Source?

17
History

• 1993 PWLib
• 1997 FireDoor
• 1998 ASN compiler
• 1998 PhonePATCH
• 1999 OpenH323
• But what about SIP?

18
History

• 1993 PWLib
• 1997 FireDoor
• 1998 ASN compiler
• 1998 PhonePATCH
• 1999 OpenH323
• 2001 OPAL

19
History

• 1993 PWLib
• 1997 FireDoor
• 1998 ASN compiler
• 1998 PhonePATCH
• 1999 OpenH323
• 2001 OPAL
• 2006 Fork!

20
Overview

• Object Oriented design
• C Classes
• C API
• Doxygen

User
API
Codec
SIP
IAX2
H.323
OS
RTP
H/W
21
C API

• Four functions
• Initialise
• Shutdown
• SendMessage
• GetMessage
• Simplified model
• Limited customisation

22
Sub-systems

• PTLib
• Protocol handlers
• Transport handlers
• Media handlers
• Addressing/Routing
• Media Format management
• Codec management

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PTLib

• Operating System abstraction
• Files/Directories
• Threads/Synchronisation
• Audio
• Video
• Configuration files
• Daemons/Services
• etc

24
PTLib

• Operating System abstraction
• Pool of basic code
• Containers (lists, arrays, strings)
• Safe containers
• I/O Channels
• Trace logging
• Memory leak checking
• etc

25
PTLib

• Operating System abstraction
• Pool of basic code
• Components
• HTTP Client/Server
• XMLRPC/SOAP
• VXML
• etc

26
PTLib

• Operating System abstraction
• Pool of basic code
• Components
• C wrappers
• Expat
• OpenSSL
• ODBC
• SDL
• etc

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Protocol Handlers

• H.323
• SIP
• IAX2
• Line Interface Device (PSTN)
• IVR/VXML
• PC Sound Card/USB
• Local

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Transport Handlers

• UDP
• TCP
• TLS
• IPv6

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Media Handlers

• Stream based
• Source in format A
• Sink in format B
• With or without transcoding
• With or without threads

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Media Formats

• Normalisation
• Unique name - G.729
• Started with fixed number of options
• Frame time
• Bit rate
• etc

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Media Formats

• Normalisation
• Unique name - G.729
• Started with fixed number of options
• Frame time
• Bit rate
• etc
• G.723.1-6k3, G.723.1-5k3

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Media Formats

• Normalisation
• Unique name - G.729
• Started with fixed number of options
• Frame time
• Bit rate
• etc
• G.723.1-6k3, G.723.1-5k3
• Video has explosion of options

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Media Formats

• List of options
• Custom
• Normalised
• Media format negotiation (merging)
• Customisation/Normalisation functions

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Codec Management

• Multi-stage format matching
• No conversion necessary
• Get from A to B direct
• Get from A to B via C

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Codec Management

• Multi-stage format matching
• RTP frame as common format

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Codec Management

• Multi-stage format matching
• RTP frame as common format
• OpalTranscoder
• Converts one format to another
• Single frame in
• 0, 1 or many frames out

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Codec Management

• Multi-stage format matching
• RTP frame as common format
• OpalTranscoder
• Directly linked or Plug-ins

38
Codec Plug-ins

• DLL/.so files
• Loaded at run time
• Currently on application start
• Relatively simple C API
• Two functions GetVersion, GetCodecs
• Tables
• Call back functions

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Class Hierarchy
OpalManager
OpalEndPoint
OpalCall
OpalSIPEndPoint
OpalLineEndPoint
OpalConnection
OpalMediaPatch
OpalSIPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
OpalUDPTransport
OpalTCPTransport
RTPSession
RTP_UDP
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Listening State
OpalManager
OpalEndPoint
OpalLineEndPoint
OpalRTPEndPoint
OpalPCSSEndPoint
OpalIVREndPoint
OpalIAX2EndPoint
OpalLocalEndPoint
OpalSIPEndPoint
OpalH323EndPoint
OpalLineInterfaceDevice
OpalListener
OpalUDPListener
OpalTCPListener
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Call State
OpalManager
OpalCall
OpalEndPoint
OpalConnection
OpalRTPConnection
OpalPCSSConnection
OpalIVRConnection
OpalIAX2Connection
OpalLocalConnection
OpalLineConnection
OpalSIPEndPoint
OpalH323EndPoint
OpalVXMLSession
OpalLine
OpalTransport
OpalLineInterfaceDevice
OpalUDPTransport
OpalTCPTransport
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Media Flow
OpalConnection
OpalMediaPatch
PThread
OpalMediaStream
OpalAudioMediaStream
OpalIVRMediaStream
OpalIAX2MediaStream
OpalLocalMediaStream
OpalLineMediaStream
OpalRTPMediaStream
OpalVXMLSession
PSoundChannel
OpalLine
RTPSession
OpalLineInterfaceDevice
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
TCP SYN
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
Incoming
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
CreateCall
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
CreateConnection
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
CreateTransport
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
ReadSetup/INVITE
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
RouteCall
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
CreateConnection
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
Ring
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
Alerting/180
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
Pick Up
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
CreateMedia
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
CreateMedia
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
CreatePatch
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Anatomy of a Call
OpalManager
OpalEndPoint
OpalCall
OpalRTPEndPoint
OpalLineEndPoint
OpalConnection
OpalLineInterfaceDevice
OpalMediaPatch
OpalRTPConnection
OpalLineConnection
OpalListener
Connect/200
OpalMediaStream
OpalLine
OpalUDPListener
OpalTCPListener
OpalRTPMediaStream
OpalLineMediaStream
OpalTransport
RTPSession
OpalLine
OpalUDPTransport
OpalTCPTransport
RTP_UDP
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Sample Code

• class MinOPAL public PProcess
• public
• MinOPAL()
• MinOPAL()
• virtual void Main()
• private
• MyManager m_manager

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Sample Code

• class MyManager public OpalManager
• public
• virtual void OnClearedCall(
• OpalCall call ///lt Connection that was
  established
• )
• PSyncPoint m_completed

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Sample Code

• class MyLocalEndPoint public OpalLocalEndPoint
• public
• virtual bool OnReadMediaFrame(
• const OpalLocalConnection connection,
  ///lt Connection for media
• const OpalMediaStream mediaStream,
  ///lt Media stream data
• RTP_DataFrame frame
  ///lt RTP frame for data
• )
• virtual bool OnWriteMediaFrame(
• const OpalLocalConnection connection,
  ///lt Connection for media
• const OpalMediaStream mediaStream,
  ///lt Media stream data
• RTP_DataFrame frame
  ///lt RTP frame for data
• )

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Sample Code

• m_manager new MyManager()
• SIPEndPoint sip new SIPEndPoint(m_manager)
  
• if (!sip-gtStartListeners(PStringArray()))
• cerr ltlt "Could not start default SIP
  listeners." ltlt endl
• return
• H323EndPoint h323 new H323EndPoint(m_manage
  r)
• if (!h323-gtStartListeners(PStringArray()))
• cerr ltlt "Could not start default H.323
  listeners." ltlt endl
• return
• new MyLocalEndPoint(m_manager, args0,
  args1)

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Sample Code

• // Route SIP/H.323 calls to the T38 endpoint
• m_manager-gtAddRouteEntry("sip.. local")
• m_manager-gtAddRouteEntry("h323.. local")
• // If no explicit protocol on URI, then send to
  SIP.
• m_manager-gtAddRouteEntry("local.
  sipltdagt")
• m_manager-gtSetUpCall("local", args2, token)

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Applications

• SimpleOPAL
• OpenPhone
• faxopal
• ivropal
• mcuopal
• opalgw

64
Whats been done

• Ekiga
• Skype Gateway
• Seminar broadcasting
• Windows Mobile handset client
• Dealer trading room
• ADSL modem
• Who knows?

65
FreeSWITCH

• mod_opal
• H.323
• IAX2
• SIP?

66
Future?

• Fax via libspandsp
• Enhance Instant Messaging
• Presence
• Innumerable random RFCs
• Whatever someone pays us to do!

67
Thank You

• Something for everyone
• www.opalvoip.org
• Questions?