RTP Ascendancy Protocol
RTCP is a sister agreement of RTP. It was aboriginal authentic in RFC 1889 and was fabricated obsolete
by RFC 3550. RTP provides out-of-band ascendancy advice for an RTP flow. It works
alongside RTP in the commitment and packaging of multimedia data, but does not transport
any abstracts itself. Although RTCP is periodically acclimated to address ascendancy packets to participants
in a alive multimedia session, the primary action of RTCP is to accommodate feedback
on the affection of account actuality provided by RTP.
RTCP is acclimated for QoS reporting. It gathers statistics on a media affiliation and information
such as bytes sent, packets sent, absent packets, jitter, feedback, and round-trip delay.
Applications use this advice to access the affection of service, conceivably application a lowcompression
codec instead of a high-compression codec.
There are several types of RTCP packets: Sender Report Packet, Receiver Report Packet,
Source Description RTCP Packet, Goodbye RTCP Packet, and application-specific RTCP
packets.
RTCP provides the afterward acknowledgment on accepted arrangement conditions:
■ RTCP provides a apparatus for hosts complex in an RTP affair to barter information
about ecology and authoritative the session. RTCP monitors the affection of
elements such as packet count, packet loss, delay, and interarrival jitter. RTCP transmits
packets as a allotment of affair bandwidth, but at a specific amount of at least
every bristles seconds.
■ The RTP accepted states that the Arrangement Time Agreement (NTP) time brand is based
on synchronized clocks. The agnate RTP time brand is about generated
and based on abstracts packet sampling. Both NTP and RTP are included in RTCP packets
by the sender of the data.
■ RTCP provides a abstracted breeze from RTP. When a articulation beck is assigned UDP port
numbers, RTP is about assigned an even-numbered anchorage and RTCP is assigned the
next odd-numbered port. Each articulation alarm has four ports assigned: RTP additional RTCP in
the address administration and RTP additional RTCP in the accept direction.