Tutorial T5 Video Over IP Magda El-Zarki

Infocom 2001 VIP - Magda El Zarki III.1 Tutorial T5 Video Over IP Magda El-Zarki (University of California at Irvine) Monday, 23 April, 2001 - Morning MPEG-4 over IP - Part 3 Magda El Zarki Dept. of ICS UC, Irvine elzarki@uci.edu Infocom 2001 VIP - Magda El Zarki III.3 Outline of Tutorial 1. Part 1: 1. Overview of Video Compression 2. The MPEG suite 3. Video Quality 2. Part 2: 1. MPEG-4 3. Part 3: 1. MPEG-4 Delivery over IP 4. Conclusions Infocom 2001 VIP - Magda El Zarki III.4 MPEG-4 Delivery over Internet • TCP/IP • SL-packet over UDP • RTP/UDP/IP • Signaling • MPEG-4 Delivery Architecture Infocom 2001 VIP - Magda El Zarki III.5 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 Infocom

2001 VIP - Magda El Zarki III.6 SL-packet over UDP/IP • SL provides: – Timing – Sequence numbering • UDP provides: – Multiplexing – Length field – Checksum service • SL+UDP as transport protocol? Infocom 2001 VIP - Magda El Zarki III.7 Some of the Problems when using SL/UDP/IP • No other media stream can be synchronized with MPEG-4 data carried directly over UDP • The dynamic scene and session control concepts cannot be extended to non-MPEG-4 data • No defined technique for synchronizing MPEG-4 streams from different servers • Streams from different servers may collide (their sources may become unresolvable at the destination) in a multicast session • Mechanisms need to be defined to protect sensitive MPEG-4 data (RTP supports FEC) • A feedback channel must be defined for quality control Infocom 2001 VIP - Magda El Zarki III.8 RTP & RTCP • Real time Transport Protocol • Real time Transport Control Protocol • A session consists of an RTP/RTCP pair of channels • Usually works over UDP/IP – Can work with other protocols • End-to-end protocol Infocom 2001 VIP - Magda El Zarki III.9 RTP Supports: • Multicasting • Payload type identification • Time stamping • Sequence numbering...

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