jrtplib.tex

jrtplib 的最新版本,比较好用的

				The type {\tt RTPAddress::IPv4Address} is used by the UDP over IPv4
				transmitter; {\tt RTPAddress::IPv6Address} is used by the UDP over
				IPv6 transmitter.
				
				The class defines the following interface:
				\begin{itemize}
					\item {\tt AddressType GetAddressType() const}\\
						Returns the type of address the actual implementation
						represents.
					\item {\tt RTPAddress *CreateCopy() const}\\
						Creates a copy of the {\tt RTPAddress} instance.
					\item {\tt bool IsSameAddress(const RTPAddress *addr) const}\\
						Checks if the address {\tt addr} is the same address as
						the one this instance represents. Implementations must be
						able ti handle a NULL argument.
					\item {\tt bool IsFromSameHost(const RTPAddress *addr) const}\\
						Checks if the address {\tt addr} represents the same host
						as this instance. Implementations must be able to handle
						a NULL argument.
				\end{itemize}
	
				\Paragraph{\tt RTPIPv4Address}\headerfile{rtpipv4address.h}\inherits{RTPAddress}
				\label{rtpipv4address}
						
					This class is used by the UDP over IPv4 transmission component.
					The following member functions are defined in this class:
					\begin{itemize}
						\item {\tt RTPIPv4Address(u\_int32\_t ip = 0, u\_int16\_t port = 0)}\\
							Creates an instance with IP address {\tt ip} and port number {\tt port}.
							Both are interpreted in host byte order.
						\item {\tt RTPIPv4Address(const u\_int8\_t ip[4], u\_int16\_t port = 0)}\\
							Creates an instance with IP address {\tt ip} and port {\tt port}.
							The port number is interpreted in host byte order.
						\item {\tt void SetIP(u\_int32\_t ip)}\\
							Sets the IP address for this instance to {\tt ip} which is
							assumed to be in host byte order.
						\item {\tt void SetIP(const u\_int8\_t ip[4])}\\
							Sets the IP address of this instance to {\tt ip}.
						\item {\tt void SetPort(u\_int16\_t port)}\\
							Sets the port number for this instance to {\tt port} which
							is interpreted in host byte order.
						\item {\tt u\_int32\_t GetIP() const}\\
							Returns the IP address contained in this instance in
							host byte order.
						\item {\tt u\_int16\_t GetPort() const}\\
							Returns the port number of this instance in host byte
							order.
					\end{itemize}

					When an {\tt RTPIPv4Address} is used in one of the multicast
					functions of the transmitter, the port number is ignored. When
					an instance is used in one of the accept or ignore functions
					of the transmitter, a zero port number represents all ports
					for the specified IP address.
					
				\Paragraph{\tt RTPIPv6Address}\headerfile{rtpipv6address.h}\inherits{RTPAddress}
				\label{rtpipv6address}

					This class is used by the UDP over IPv4 transmission component.
					The following member functions are defined:
					\begin{itemize}
						\item {\tt RTPIPv6Address()}\\
							Creates an instance with IP address and port number set to
							zero.
						\item {\tt RTPIPv6Address(const u\_int8\_t ip[16], u\_int16\_t port = 0)}\\
							Creates an instance with IP address {\tt ip} and port
							number {\tt port}. The port number is assumed to be in
							host byte order.
						\item {\tt RTPIPv6Address(in6\_addr ip, u\_int16\_t port = 0)}\\
							Creates an instance with IP address {\tt ip} and port
							number {\tt port}. The port number is assumed to be in
							host byte order.
						\item {\tt void SetIP(in6\_addr ip)}\\
							Sets the IP address for this instance to {\tt ip}.
						\item {\tt void SetIP(const u\_int8\_t ip[16])}\\
							Sets the IP address for this instance to {\tt ip}.
						\item {\tt void SetPort(u\_int16\_t port)}\\
							Sets the port number for this instance to {\tt port}, which
							is interpreted in host byte order.
						\item {\tt void GetIP(u\_int8\_t ip[16]) const}\\
							Copies the IP address of this instance in {\tt ip}.
						\item {\tt in6\_addr GetIP() const}\\
							Returns the IP address of this instance.
						\item {\tt u\_int16\_t GetPort() const}\\
							Returns the port number contained in this instance in
							host byte order.
					\end{itemize}
					
					When an {\tt RTPIPv6Address} is used in one of the multicast
					functions of the transmitter, the port number is ignored. When
					an instance is used in one of the accept or ignore functions
					of the transmitter, a zero port number represents all ports
					for the specified IP address.

			\subsubsection{\tt RTPRawPacket}\headerfile{rtprawpacket.h}
				
				The {\tt RTPRawPacket} class is used by the transmission component
				to store the incoming RTP and RTCP data in. It has the following 
				interface:
				\begin{itemize}
					\item {\tt RTPRawPacket(u\_int8\_t *data, size\_t datalen, RTPAddress *address, RTPTime \&recvtime, bool rtp)}\\
						Creates an instance which stores data from {\tt data} with
						length {\tt datalen}. Only the pointer to the data is stored,
						no actual copy is made! The address from which this packet
						originated is set to {\tt address} and the time at which
						the packet was received is set to {\tt recvtime}. The flag
						which indicates whether this data is RTP or RTCP data is set
						to {\tt rtp}.
					\item {\tt u\_int8\_t *GetData()}\\
						Returns the pointer to the data which is contained in this
						packet.
					\item {\tt size\_t GetDataLength() const}\\
						Returns the length of the packet described by this instance.
					\item {\tt RTPTime GetReceiveTime() const}\\
						Returns the time at which this packet was received.
					\item {\tt const RTPAddress *GetSenderAddress() const}\\
						Returns the address stored in this packet.
					\item {\tt bool IsRTP() const}\\
						Returns {\tt true} if this data is RTP data, {\tt false} if it is RTCP
						data.
					\item {\tt void ZeroData()}\\
						Sets the pointer to the data stored in this packet to zero.
						This will prevent a {\tt delete} call for the actual data when
						the destructor of {\tt RTPRawPacket} is called. This function
						is used by the {\tt RTPPacket} and {\tt RTCPCompoundPacket}
						classes to obtain the packet data (without having to copy it)
						and to make sure the data isn't deleted when the destructor
						of {\tt RTPRawPacket} is called.
				\end{itemize}

			\subsubsection{\tt RTPPacket}\headerfile{rtppacket.h}
	
				The {\tt RTPPacket} class can be used to parse a {\tt RTPRawPacket}
				instance if it represents RTP data. The class can also be used to
				create a new RTP packet according to the parameters specified by
				the user. The interface of this class is the following:
				\begin{itemize}
					\item {\tt RTPPacket(RTPRawPacket \&rawpack)}\\
						Creates an RTPPacket instance based upon the data in
						{\tt rawpack}.
					\item {\tt RTPPacket(u\_int8\_t payloadtype, const void *payloaddata, size\_t payloadlen, u\_int16\_t seqnr,
									u\_int32\_t timestamp, u\_int32\_t ssrc, bool gotmarker, u\_int8\_t numcsrcs, const u\_int32\_t *csrcs,
									bool gotextension, u\_int16\_t extensionid, u\_int16\_t extensionlen\_numwords, const void *extensiondata,
									size\_t maxpacksize = 0)}\\
						Creates an new buffer for an RTP packet and fills in the fields
						according to the specified parameters. If {\tt maxpacksize} is
						not equal to zero, an error is generated if the total packet size
						would exceed {\tt maxpacksize}. The arguments of the constructor
						are self-explanatory. Note that the size of a header extension is
						specified in a number of $32$-bit words.
					\item {\tt RTPPacket(u\_int8\_t payloadtype, const void *payloaddata, size\_t payloadlen, u\_int16\_t seqnr,
									u\_int32\_t timestamp, u\_int32\_t ssrc, bool gotmarker, u\_int8\_t numcsrcs, const u\_int32\_t *csrcs,
									bool gotextension, u\_int16\_t extensionid, u\_int16\_t extensionlen\_numwords, const void *extensiondata,
									void *buffer, size\_t buffersize)}\\
						Pretty much the same function as the previous one, except that data is stored
						in an external buffer {\tt buffer} with buffer size {\tt buffersize}.
					\item {\tt int GetCreationError() const}\\
						If an error occurred in one of the constructors, this function
						returns the error code.
					\item {\tt bool HasExtension() const}\\
						Returns {\tt true} if the RTP packet has a header extension and
						{\tt false} otherwise.
					\item {\tt bool HasMarker() const}\\
						Returns {\tt true} is the marker bit was set and {\tt false}
						otherwise.
					\item {\tt int GetCSRCCount() const}\\
						Returns the number of CSRCs contained in this packet.
					\item {\tt u\_int32\_t GetCSRC(int num) const}\\
						Returns a specific CSRC identifier. The parameter {\tt num} 
						can go from $0$ to {\tt GetCSRCCount()}-$1$.
					\item {\tt u\_int8\_t GetPayloadType() const}\\
						Returns the payload type of the packet.
					\item {\tt u\_int32\_t GetExtendedSequenceNumber() const}\\
						Returns the extended sequence number of the packet. When
						the packet is just received, only the low $16$ bits will
						be set. The high $16$ bits can be filled in later.
					\item {\tt u\_int16\_t GetSequenceNumber() const}\\
						Returns the sequence number of this packet.
					\item {\tt void SetExtendedSequenceNumber(u\_int32\_t seq)}\\
						Sets the extended sequence number of this packet to {\tt seq}.
					\item {\tt u\_int32\_t GetTimestamp() const}\\
						Returns the timestamp of this packet.
					\item {\tt u\_int32\_t GetSSRC() const}\\
						Returns the SSRC identifier stored in this packet.
					\item {\tt u\_int8\_t *GetPacketData() const}\\
						Returns a pointer to the data of the entire packet.
					\item {\tt u\_int8\_t *GetPayloadData() const}\\
						Returns a pointer to the actual payload data.
					\item {\tt size\_t GetPacketLength() const}\\
						Returns the length of the entire packet.
					\item {\tt size\_t GetPayloadLength() const}\\
						Returns the payload length.
					\item {\tt u\_int16\_t GetExtensionID() const}\\
						If a header extension is present, this function
						returns the extension identifier.
					\item {\tt u\_int8\_t *GetExtensionData() const}\\
						Returns a pointer to the header extension data.
					\item {\tt size\_t GetExtensionLength() const}\\
						Returns the length of the header extension data.
				\end{itemize}

			\subsubsection{\tt RTCPCompoundPacket}\headerfile{rtpcompoundpacket.h}

				This class describes an RTCP compound packet and has the following
				interface:
				\begin{itemize}
					\item {\tt RTCPCompoundPacket(RTPRawPacket \&rawpack)}\\
						Creates an {\tt RTCPCompoundPacket} instance from the
						data in {\tt rawpack}.
					\item {\tt int GetCreationError()}\\
						If the raw packet data in the constructor could not
						be parsed, this function returns the error code of
						what went wrong. If the packet had an invalid format,
						the return value is {\tt ERR\_\-RTP\_\-RTCPCOMPOUND\_\-INVALID\-PACKET}.
					\item {\tt u\_int8\_t *GetCompoundPacketData()}\\
						Returns a pointer to the data of the entire RTCP compound packet.
					\item {\tt size\_t GetCompoundPacketLength()}\\
						Returns the size of the entire RTCP compound packet
					\item {\tt void GotoFirstPacket()}\\
						Starts the iteration over the individual RTCP packets in
						the RTCP compound packet.
					\item {\tt RTCPPacket *GetNextPacket()}\\
						Returns a pointer to the next individual RTCP packet. Note
						that no {\tt delete} call may be done on the {\tt RTCPPacket}
						instance which is returned. The {\tt RTCPPacket} class is
						described below.
				\end{itemize}
				
				\Paragraph{\tt RTCPPacket}\headerfile{rtcppacket.h}
					
					The class {\tt RTCPPacket} is a base class for specific types
					of RTCP packets. The following type in the {\tt RTCPPacket}
					class identifies the different packet types:
					\begin{verbatim}
						enum PacketType { SR, RR, SDES, BYE, APP, Unknown };
					\end{verbatim}

					The class contains the following member functions:
					\begin{itemize}
						\item {\tt bool IsKnownFormat() const}\\
							Returns {\tt true} if the subclass was able to interpret
							the data and {\tt false} otherwise.
						\item {\tt PacketType GetPacketType() const}\\
							Returns the actual packet type which the subclass
							implements:
							\begin{itemize}
								\item {\tt RTCPPacket::SR}: indicates an {\tt RTCPSRPacket} instance
								\item {\tt RTCPPacket::RR}: indicates an {\tt RTCPRRPacket} instance
								\item {\tt RTCPPacket::SDES}: indicates an {\tt RTCPSDESPacket} instance
								\item {\tt RTCPPacket::BYE}: indicates an {\tt RTCPBYEPacket} instance
								\item {\tt RTCPPacket::APP}: indicates an {\tt RTCPAPPPacket} instance
								\item {\tt RTCPPacket::Unknown}: indicates an {\tt RTCPUnknownPacket} instance
							\end{itemize}
						\item {\tt u\_int8\_t *GetPacketData()}\\
							Returns a pointer to the data of this RTCP packet.
						\item {\tt size\_t GetPacketLength() const}\\
							Returns the length of this RTCP packet.
					\end{itemize}

				\Paragraph{\tt RTCPSRPacket}\headerfile{rtcpsrpacket.h}\inherits{RTCPPacket}
					
					This class describes an RTCP sender report packet. The interface
					is the following:
					\begin{itemize}
						\item {\tt RTCPSRPacket(u\_int8\_t *data, size\_t datalen)}\\
							Creates an instance based on the data in {\tt data} with
							length {\tt datalen}. Since the {\tt data} pointer
							is referenced inside the class (no copy of the data is
							made) one must make sure that the memory it points to is
							valid as long as the class instance exists.
						\item {\tt u\_int32\_t GetSenderSSRC() const}\\