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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
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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 RTP RTCP UDP IP
RTP/RTCP RTP HEADER
Reference • www.cs.columbia.edu/~hgs/rtp/papers.html