Class RtpChannel

Class for sending and receiving Real Time Protocol (RTP) media such as audio, video and text (RTT). Each instance of an RtpChannel class handles a single media type.

Inheritance

object

RtpChannel

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: SipLib.Rtp

Assembly: SipLib.dll

Syntax

public class RtpChannel

Remarks

Follow these steps to create and use an RtpChannel object.

1. Call the CreateFromSdp() method with the offered SDP and offered media description and the answered SDP and the answered media description after the media description negotiation has been completed.
2. Hook the events of the RtpChannel class. At least the RtpPacketReceived event should be handled.
3. Call the StartListening() method to start the RtpChannel.
4. Call the Send() method to send a new RTP packet containing new media.

When the media session ends, unhook the events and call the Shutdown() method to release all resources held by the RtpChannel object.

Properties

CertificateFingerprint

Gets the fingerprint of the self-signed X.509 certificate that will be used for DTLS-SRTP. The certificate is a required SDP attribute for calls that offer or answer DTLS-SRTP media encryption.

The RtpChannel class automatically creates a self-signed X.509 certificate that will be used for all instances of the RtpChannel class for an application session.

Declaration

public static string? CertificateFingerprint { get; }

Property Value

Type	Description
string	Returns null if there was an error during creation of the self-signed X.509 certificate.

IsDtlsSrtp

Returns true if this channel is using DTLS-SRTP encryption

Declaration

public bool IsDtlsSrtp { get; }

Property Value

Type	Description
bool

IsSdesSrtp

Returns true if this channel is using SDES-SRTP encryption

Declaration

public bool IsSdesSrtp { get; }

Property Value

Type	Description
bool

LocalPort

Gets the port number of the local IPEndPoint.

Declaration

public int LocalPort { get; }

Property Value

Type	Description
int

MediaType

Gets the media type for this RtpChannel

Declaration

public string MediaType { get; }

Property Value

Type	Description
string	Will be one of "audio", "video" or "text" (for RTT)

RemoteRtcpEndPoint

Gets or sets the RTCP IPEndPoint of the remote

Declaration

public IPEndPoint RemoteRtcpEndPoint { get; set; }

Property Value

Type	Description
IPEndPoint

RemoteRtpEndPoint

Gets or sets the RTP IPEndPoint of the remote.

Declaration

public IPEndPoint RemoteRtpEndPoint { get; set; }

Property Value

Type	Description
IPEndPoint

SSRC

Gets or sets the RTP SSRC for this RtpChannel. By default, the SSRC is set to a random unsigned 32-bit number so there is usually no need to change it by calling the setter.

Declaration

public uint SSRC { get; set; }

Property Value

Type	Description
uint

Methods

CreateFromSdp(bool, Sdp, MediaDescription, Sdp, MediaDescription, bool, string?)

Creates an RtpChannel using the offered and answered Session Description Protocol (SDP) parameters.

Declaration

public static (RtpChannel?, string?) CreateFromSdp(bool Incoming, Sdp OfferedSdp, MediaDescription OfferedMd, Sdp AnsweredSdp, MediaDescription AnsweredMd, bool enableRtcp, string? CNAME)

Parameters

Type	Name	Description
bool	Incoming	Set to true if the call is incoming.
Sdp	OfferedSdp	The SDP that was offered. If Incoming is true, then this parameter must be the Sdp object that was received in an INVITE request. Else, this parameter must be the Sdp object that the client sent in an INVITE request.
MediaDescription	OfferedMd	The offered media description parameter block from the offered SDP for the media type that the RtpChannel will handle.
Sdp	AnsweredSdp	The SDP that was answered. If Incoming is true, then this parameter must be the Sdp object that the server sent in response to an INVITE request that it received. Else, this parameter must the the Sdp object that the client received in response to the INVITE that it sent.
MediaDescription	AnsweredMd	The answered media description parameter block from the answered SDP for the media type that the RtpChannel will handle.
bool	enableRtcp	If true, then RTCP packets will be sent periodically.
string	CNAME	Cononical name to use for sending SDES RTCP packets that identify the media source. If null, then a default CNAME will be automatically generated.

Returns

Type	Description
(RtpChannel, string)	Returns a (RtpChannel, string) tuple. If the RtpChannel return value is null then an error was detected and the string return value will contain an explanation of the error. If the RtpChannel return value is not null then the string return value will be null.

Send(RtpPacket)

Sends an RTP packet to the remote endpoint

Declaration

public void Send(RtpPacket rtpPacket)

Parameters

Type	Name	Description
RtpPacket	rtpPacket

Shutdown()

Shuts down this RtpChannel and releases all resources. The RtpChannel object cannot be used after this method is called.

Declaration

public void Shutdown()

StartListening()

Starts the listener threads for RTP and RTCP.

Declaration

public void StartListening()

Events

DtlsHandshakeFailed

Event that is fired if the DTLS-SRTP handshake failed

Declaration

public event DtlsHandshakeFailedDelegate? DtlsHandshakeFailed

Event Type

Type	Description
DtlsHandshakeFailedDelegate

ReceiveStatisticsReady

Event that is fired when new receive side statistics are ready. This event if fired only if RTCP is enabled for the RtpChannel and the media type is audio. This event will be fired every 5 seconds.

Declaration

public event ReceiveStatisticsReadyDelegate? ReceiveStatisticsReady

Event Type

Type	Description
ReceiveStatisticsReadyDelegate

RtcpPacketReceived

Event that is fired when a RTCP packet is received.

Declaration

public event RtcpPacketReceivedDelegate? RtcpPacketReceived

Event Type

Type	Description
RtcpPacketReceivedDelegate

RtcpPacketSent

Event that is fired when this class sends an RTCP packet.

Declaration

public event RtcpPacketSentDelegate? RtcpPacketSent

Event Type

Type	Description
RtcpPacketSentDelegate

RtpPacketReceived

Event that is fired when a RTP media packet has been received by this RtpChannel

Declaration

public event RtpPacketReceivedDelegate? RtpPacketReceived

Event Type

Type	Description
RtpPacketReceivedDelegate

RtpPacketSent

Event that is fired when a RTP packet has been sent by this RtpChannel. This event is used for logging media when using an active SIP media recorder (SIPREC).

Declaration

public event RtpPacketSentDelegate? RtpPacketSent

Event Type

Type	Description
RtpPacketSentDelegate