RTP & RCTP
RTP and RCTP are both protocols used for data transmission in multimedia services,
these protocols work through IP networks. They work together to ease effective data
transmission in real time in applications as VoIP.
RTP is used for delivering audio and video over IP networks, some of the most
important characteristic about it are:
Packetization: RTP breaks video and audio data into packets, each one of them
contains part of the media stream with header information.
Sequence Numbering: RTP protocol assigns a sequence number to each packet,
allowing the receiver to arrange them in the correct order to organize them and
as that way detect packet loss.
Timestamping: RTP protocol is able to make timestamps for synchronization
and timing control as that way the receiver can reconstruct the original timing
of the transmitted data.
Payload Identification: RTP is able to identify the type of data carried using a
payload type field in its header. This is useful at the moment of interpret the
packet contents.
Synchronization identification: RTP uses the source of the media stream in
order to synchronize with it using SSRC field. This is important in media sessions
like multiparty communication.
RTCP: Real Time Transport Control Protocol, is used in conjuction with RTCP, is
responsible for monitoring the quality of the transmission. This is very
important to know about the packet loss, delay and jitter.
Codec Independence: RTP doesn’t enforce any specific audio or video encoding
format so it can work with various codecs facilitating interoperability among
different systems.
Error Detection and Correction: Although RTP doesn’t have error correction
mechanisms it does include a checksum for error detection.
Dynamic Payload Types: RTP allows dynamic assignment of payload types
which means that different types of media streams can be carried through the
same session.
MT & UT: RTP supports both multicast and unicast transmission which makes it
suitable for Point to Point or Point to Multipoint communication systems.
Protocol Description Characteristics
* Real time data delivery
RTP * Provides temporal
(Real Time Protocol) Standar internet protocol synchronization mechanism
used for real data for different multimedia
transmision like audio and Flow.
video through IP networks. * Uses secuency
numbers to reconstruct
packets in a orderly manner.
* Provides information
RCTP about transmission quality
(Real Time Control like packets loss and latency.
Complementary protocol, is * Permits participants
Protocol)
used to control the quality in identification and bandwith
RTP services in real-time asignation.
transmission session * It is focused in the
control about multimedia
data.
Although both of these protocols are used in order the complement each other in
multimedia data transmission, there are some differences between them, for example:
RTP is focused on the real time multimedia data transmisión, while RCTP is used
for control and feedback associated with transmisión quality.
RTP transports the actual multimedia data, while RCTP doesn’t but instead it
provides control information about the multimedia session.
RTP generally has a higher transmisión frequency since it is intended for real
time transmisión, while RTCP is transsmited periodically at a much lower
frequency.
All of these considerations guarantee an optimal quality of service when transmitting
multimedia data. By having feedback from the session, actions can be taken to improve
the QoS which is important to maintain a stable transmission. For example, there are
sessions where RTP protocol is used like:
VoIP: Transmission of voice content over IP networks
Video Conferencing: Transmission of voice and multimedia in real time in
unicast or multicast communication systems. RTP forms an integral part of the
infrastructure used in video conferencing systems
Streaming Media Services: in this type of service data is carried over internet,
this could be in real time or recorded on the web. RTP serves as a key protocol
for transmitting audio and video content.
Interactive Online Gaming: In order to reduce the latency in this kind of
services RTP is used to transport effective data in real time.
Unified Communications: is a framework that integrates various
communication tools and channels within an organization. RTP is a key
component in enabling real time audio and video communication within UC
systems.
REFERENCES
[1] Introducción a RTP Y RTCP - UC3M,
http://www.it.uc3m.es/labsimitis/sesiones/teoria/07_Intro_RTP.pdf (accessed
Nov. 12, 2023).
[2] V. S. Ojeda, Instituto Politécnico Nacional Centro de Investigación en
Computación Tesis,
https://tesis.ipn.mx/bitstream/handle/123456789/30417/6.%20TESIS_Hosseini
%20Saravani_Protegido.pdf?sequence=1 (accessed Nov. 13, 2023).
