RTP/RTCP – Real Time Transport Protocol/ Real Time Control Protocol

Presented by

Manoj Sivakumar

Overview

Motivation RTP/RTCP description

Motivation

TCP/IP Not suitable for real-time

Retransmissions can lead to high delay and cause delay jitter Does not support multicast Congestion control mechanism (slow start) not suitable for

AV media UDP/IP

No defined technique for synchronizing Streams from different servers may collide A feedback channel must be defined for quality control

RTP/RTCP

A session consists of an RTP/RTCP pair of channels

Usually works over UDP/IP End-to-end protocol

RTP/RTCP

RTP Features Multicasting Payload type identification Time shaping Sequencing Delivery monitoring

RTP/RTCP

RTP Issues No QoS guarantees No guarantee of packet delivery

RTP Timestamp (TS) and Sequence Number (SN) TS used to order packets in correct timing order SN to detect packet loss For a video frame that spans multiple packets –

TS is same but SN is different

RTP/RTCP

RTCP Synchronize across different media

streams Provide feedback on the quality of data

using lost packet counts Identify and keep track of participants Retransmission requests

RTP/RTCP

Media Application

RTCP

RTP

UDP

IP

RTP/RTCPRTP HEADER

Reference

www.cs.columbia.edu/~hgs/rtp/papers.html