H323Capability Class Referenceabstract

`#include <h323caps.h>`

Inheritance diagram for H323Capability:

## Public Member Functions

Construction
| H323Capability ()
Overrides from class PObject
Comparison | Compare (const PObject &obj) const
void | PrintOn (ostream &strm) const

## Protected Member Functions

OpalMediaFormat & | GetWritableMediaFormat () const

## Protected Attributes

unsigned | assignedCapabilityNumber
CapabilityDirection | capabilityDirection
| Unique ID assigned to capability. More...

## Friends

class | H323Capabilities

## Identification functions

enum | MainTypes { e_Audio, e_Video, e_Data, e_UserInput, e_GenericControl, e_NumMainTypes }
virtual MainTypes | GetMainType () const =0
virtual unsigned | GetSubType () const =0
virtual PString | GetFormatName () const =0

## Operations

enum | { DefaultAudioSessionID = 1, DefaultVideoSessionID = 2, DefaultDataSessionID = 3, DefaultH224SessionID = 4 }
virtual unsigned | GetDefaultSessionID () const
virtual void | SetTxFramesInPacket (unsigned frames)
virtual unsigned | GetTxFramesInPacket () const
virtual unsigned | GetRxFramesInPacket () const
virtual H323Channel * | CreateChannel (H323Connection &connection, H323Channel::Directions dir, unsigned sessionID, const H245_H2250LogicalChannelParameters *param) const =0
static H323Capability * | Create (const PString &name)

## Protocol manipulation

enum | CommandType { e_TCS, e_OLC, e_ReqMode }
virtual PBoolean | OnSendingPDU (H245_Capability &pdu) const =0
virtual PBoolean | OnSendingPDU (H245_DataType &pdu) const
virtual PBoolean | OnSendingPDU (H245_ModeElement &pdu) const =0
virtual PBoolean | OnReceivedPDU (const H245_Capability &pdu)
virtual PBoolean | OnReceivedPDU (const H245_DataType &pdu, PBoolean receiver)
virtual PBoolean | IsMatch (const PASN_Choice &subTypePDU, const PString &mediaPacketization) const
virtual PBoolean | IsUsable (const H323Connection &connection) const

## Member variable access

enum | CapabilityDirection { e_Unknown, e_Receive, e_Transmit, e_ReceiveAndTransmit, e_NoDirection, NumCapabilityDirections }
CapabilityDirection | GetCapabilityDirection () const
void | SetCapabilityDirection (CapabilityDirection dir)
unsigned | GetCapabilityNumber () const
| Get unique capability number. More...
void | SetCapabilityNumber (unsigned num)
| Set unique capability number. More...
OpalMediaFormat | GetMediaFormat () const
bool | UpdateMediaFormat (const OpalMediaFormat &format)
RTP_DataFrame::PayloadTypes | GetPayloadType () const
| Get the payload type for the capaibility. More...
void | SetPayloadType (RTP_DataFrame::PayloadTypes pt)
| Set the payload type for the capaibility. More...
virtual void | AttachQoS (RTP_QOS *)
| Attach a QoS specification to this channel. More...

## Detailed Description

This class describes the interface to a capability of the endpoint, usually a codec, used to transfer data via the logical channels opened and managed by the H323 control channel.

Note that this is not an instance of the codec itself. Merely the description of that codec. There is typically only one instance of this class contained in the capability tables of the endpoint. There may be several instances of the actualy codec managing the conversion of an individual stream of data.

An application may create a descendent off this class and override functions as required for describing a codec that it implements.

## Member Enumeration Documentation

anonymous enum

Enumerator
DefaultAudioSessionID |
DefaultVideoSessionID |
DefaultDataSessionID |
DefaultH224SessionID |

enum H323Capability::CapabilityDirection

Enumerator
e_Unknown |
e_Receive |
e_Transmit |
e_ReceiveAndTransmit |
e_NoDirection |
NumCapabilityDirections |

enum H323Capability::CommandType

Enumerator
e_TCS |
e_OLC |
e_ReqMode |

enum H323Capability::MainTypes

Enumerator
e_Audio | Audio codec capability.
e_Video | Video codec capability.
e_Data | Arbitrary data capability.
e_UserInput | User Input capability.
e_GenericControl | Generic Control.
e_NumMainTypes | Count of main types.

## Constructor & Destructor Documentation

H323Capability::H323Capability | ( |  | ) |

Create a new capability specification.

## Member Function Documentation

virtual void H323Capability::AttachQoS | ( | RTP_QOS * |  | ) |

inline virtual

Attach a QoS specification to this channel.

Reimplemented in H323RealTimeCapability.

Comparison H323Capability::Compare | ( | const PObject & | obj | ) | const

Compare two capability instances. This compares the main and sub-types of the capability.

static H323Capability* H323Capability::Create | ( | const PString & | name | ) |

static

Create an H323Capability descendant given a string name. This uses the registration system to create the capability.

Parameters

  name | Name of capability

virtual H323Channel* H323Capability::CreateChannel | ( | H323Connection & | connection,
|  | H323Channel::Directions | dir,
|  | unsigned | sessionID,
|  | const H245_H2250LogicalChannelParameters * | param
| ) |  | const

pure virtual

Create the channel instance, allocating resources as required. This creates a logical channel object appropriate for the parameters provided. Not if param is NULL, sessionID must be provided, otherwise this is taken from the fields in param.

Parameters

  connection | Owner connection for channel
  dir | Direction of channel
  sessionID | Session ID for RTP channel
  param | Parameters for channel

Implemented in H323_UserInputCapability, H323GenericControlCapability, H323RealTimeCapability, and H323_T120Capability.

CapabilityDirection H323Capability::GetCapabilityDirection | ( |  | ) | const

inline

Get the direction for this capability.

References capabilityDirection.

unsigned H323Capability::GetCapabilityNumber | ( |  | ) | const

inline

Get unique capability number.

References assignedCapabilityNumber.

virtual unsigned H323Capability::GetDefaultSessionID | ( |  | ) | const

virtual

Get the default RTP session. This function gets the default RTP session ID for the capability type. For example audio capabilities return the value H323Capability::DefaultAudioSessionID etc.

The default behaviour returns zero, indicating it is not an RTP based capability.

Reimplemented in H323DataCapability, H323VideoCapability, and H323AudioCapability.

virtual PString H323Capability::GetFormatName | ( |  | ) | const

pure virtual

Get the name of the media data format this class represents.

Implemented in H323_UserInputCapability, H323_G711Capability, H323H239ControlCapability, H323H239VideoCapability, H323H263PluginCapability, H323H261PluginCapability, H323CodecPluginGenericVideoCapability, H323CodecPluginNonStandardVideoCapability, H323CodecPluginGenericAudioCapability, H323CodecPluginNonStandardAudioCapability, H323AudioPluginCapability, H323_H224_HDLCTunnelingCapability, H323_T120Capability, and H323_H224_AnnexQCapability.

virtual MainTypes H323Capability::GetMainType | ( |  | ) | const

pure virtual

Get the main type of the capability.

This function is overridden by one of the three main sub-classes off which real capabilities would be descendend.

Implemented in H323_UserInputCapability, H323DataCapability, H323GenericControlCapability, H323VideoCapability, and H323AudioCapability.

OpalMediaFormat H323Capability::GetMediaFormat | ( |  | ) | const

Get media format of the media data this class represents.

Referenced by GetPayloadType().

RTP_DataFrame::PayloadTypes H323Capability::GetPayloadType | ( |  | ) | const

inline

Get the payload type for the capaibility.

References GetMediaFormat(), and OpalMediaFormat::GetPayloadType().

virtual unsigned H323Capability::GetRxFramesInPacket | ( |  | ) | const

virtual

Get the maximum size (in frames) of data that can be received in a single PDU.

The default behaviour returns the value 1.

Reimplemented in H323AudioCapability.

virtual unsigned H323Capability::GetSubType | ( |  | ) | const

pure virtual

Get the sub-type of the capability. This is a code dependent on the main type of the capability.

Implemented in H323_UserInputCapability, H323_G711Capability, H323NonStandardDataCapability, H323GenericControlCapability, H323ExtendedVideoCapability, H323GenericVideoCapability, H323NonStandardVideoCapability, H323GenericAudioCapability, H323NonStandardAudioCapability, H323H263PluginCapability, H323H261PluginCapability, H323AudioPluginCapability, H323_H224_HDLCTunnelingCapability, H323_T120Capability, and H323_H224_AnnexQCapability.

virtual unsigned H323Capability::GetTxFramesInPacket | ( |  | ) | const

virtual

Get the maximum size (in frames) of data that will be transmitted in a single PDU.

The default behaviour returns the value 1.

Reimplemented in H323AudioCapability.

OpalMediaFormat& H323Capability::GetWritableMediaFormat | ( |  | ) | const

protected

Referenced by SetPayloadType().

virtual PBoolean H323Capability::IsMatch | ( | const PASN_Choice & | subTypePDU,
|  | const PString & | mediaPacketization
| ) |  | const

virtual

Compare the PDU part of the capability.

Parameters

  subTypePDU | sub-type PDU of H323Capability
  mediaPacketization | Media packetization used

Reimplemented in H323NonStandardDataCapability, H323GenericControlCapability, H323ExtendedVideoCapability, H323GenericVideoCapability, H323NonStandardVideoCapability, H323GenericAudioCapability, H323NonStandardAudioCapability, and H323H263PluginCapability.

virtual PBoolean H323Capability::IsUsable | ( | const H323Connection & | connection | ) | const

virtual

Validate that the capability is usable given the connection. This checks agains the negotiated protocol version number and remote application to determine if this capability should be used in TCS or OLC pdus.

The default behaviour returns true.

Reimplemented in H323_UserInputCapability.

virtual PBoolean H323Capability::OnReceivedPDU | ( | const H245_Capability & | pdu | ) |

virtual

This function is called whenever and incoming TerminalCapabilitySet PDU is received on the control channel, and a new H323Capability descendent was created. This completes reading fields from the PDU into the classes members.

If the function returns false then the received PDU codec description is not supported, so will be ignored.

The default behaviour sets the capabilityDirection member variable from the PDU and then returns true. Note that this means it is very important to call the ancestor function when overriding.

Parameters

  pdu | PDU to get information from

Reimplemented in H323_UserInputCapability, H323DataCapability, H323GenericControlCapability, H323VideoCapability, and H323AudioCapability.

virtual PBoolean H323Capability::OnReceivedPDU | ( | const H245_DataType & | pdu,
|  | PBoolean | receiver
| ) |  |

virtual

This function is called whenever and incoming OpenLogicalChannel PDU has been used to construct the control channel. It allows the capability to set from the PDU fields, information in members specific to the class.

The default behaviour is pure.

Parameters

  pdu | PDU to get information from
  receiver | Is receiver OLC

Reimplemented in H323_UserInputCapability, H323DataCapability, H323VideoCapability, and H323AudioCapability.

virtual PBoolean H323Capability::OnSendingPDU | ( | H245_Capability & | pdu | ) | const

pure virtual

This function is called whenever and outgoing TerminalCapabilitySet PDU is being constructed for the control channel. It allows the capability to set the PDU fields from information in members specific to the class.

The default behaviour is pure.

Parameters

  pdu | PDU to set information on

Implemented in H323_UserInputCapability, H323DataCapability, H323GenericControlCapability, H323VideoCapability, and H323AudioCapability.

virtual PBoolean H323Capability::OnSendingPDU | ( | H245_DataType & | pdu | ) | const

virtual

This function is called whenever and outgoing OpenLogicalChannel PDU is being constructed for the control channel. It allows the capability to set the PDU fields from information in members specific to the class.

The default behaviour is pure.

Parameters

  pdu | PDU to set information on

Reimplemented in H323_UserInputCapability, H323DataCapability, H323VideoCapability, and H323AudioCapability.

virtual PBoolean H323Capability::OnSendingPDU | ( | H245_ModeElement & | pdu | ) | const

pure virtual

This function is called whenever and outgoing RequestMode PDU is being constructed for the control channel. It allows the capability to set the PDU fields from information in members specific to the class.

The default behaviour is pure.

Parameters

  pdu | PDU to set information on

Implemented in H323_UserInputCapability, H323DataCapability, H323GenericControlCapability, H323VideoCapability, and H323AudioCapability.

void H323Capability::PrintOn | ( | ostream & | strm | ) | const

Print out the object to the stream, virtual version of << operator.

void H323Capability::SetCapabilityDirection | ( | CapabilityDirection | dir | ) |

inline

Set the direction for this capability.

Parameters

  dir | New direction code

References capabilityDirection.

void H323Capability::SetCapabilityNumber | ( | unsigned | num | ) |

inline

Set unique capability number.

References assignedCapabilityNumber.

void H323Capability::SetPayloadType | ( | RTP_DataFrame::PayloadTypes | pt | ) |

inline

Set the payload type for the capaibility.

References GetWritableMediaFormat(), and OpalMediaFormat::SetPayloadType().

virtual void H323Capability::SetTxFramesInPacket | ( | unsigned | frames | ) |

virtual

Set the maximum size (in frames) of data that will be transmitted in a single PDU.

This will also be the desired number that will be sent by most codec implemetations.

The default behaviour does nothing.

Parameters

  frames | Number of frames per packet

Reimplemented in H323AudioCapability.

bool H323Capability::UpdateMediaFormat | ( | const OpalMediaFormat & | format | ) |

Set media format option for the media data this class represents.

## Friends And Related Function Documentation

friend class H323Capabilities

friend

## Field Documentation

unsigned H323Capability::assignedCapabilityNumber

protected

Referenced by GetCapabilityNumber(), and SetCapabilityNumber().

CapabilityDirection H323Capability::capabilityDirection

protected

Unique ID assigned to capability.

Referenced by GetCapabilityDirection(), and SetCapabilityDirection().

The documentation for this class was generated from the following file:

- h323caps.h