RTPRTCP Real Time Transport Protocol Real Time Control

RTP/RTCP – Real Time Transport Protocol/ Real Time Control Protocol Presented by Manoj Sivakumar

Overview n n Motivation RTP/RTCP description

Motivation n TCP/IP ¡ Not suitable for real-time n ¡ ¡ n 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 n n n A session consists of an RTP/RTCP pair of channels Usually works over UDP/IP End-to-end protocol

RTP/RTCP n RTP Features ¡ ¡ ¡ Multicasting Payload type identification Time shaping Sequencing Delivery monitoring

RTP/RTCP n RTP Issues ¡ ¡ n No Qo. S 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 n 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/RTCP RTP HEADER

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