Streaming Video over the Internet Dapeng Wu Electrical & Computer Engineering University of Florida

2 What is Streaming Video? AccessSW Data path AccessSW Domain A Domain B Domain C Internet AccessSW Source Receiver 2 Receiver 1 Download mode: no delay bound Streaming mode: delay bound cnn.com RealPlayer

3 Outline Challenges for quality video transport An architecture for video streaming – –Video compression – –Application-layer QoS control – –Continuous media distribution services – –Streaming server – –Media synchronization mechanisms – –Protocols for streaming media Summary

4 Time-varying Available Bandwidth Data path AccessSW Domain A Domain B AccessSW Source Receiver 56 kb/s R>=56 kb/s R<56 kb/s cnn.com RealPlayer No bandwidth reservation

5 Time-varying Delay Data path AccessSW Domain A Domain B AccessSW Source Receiver 56 kb/s cnn.com RealPlayer Delayed packets regarded as lost

6 Effect of Packet Loss Data path AccessSW Domain A Domain B AccessSW Source Receiver No packet loss Loss of packets No retransmission

7 Unicast vs. Multicast Unicast Multicast Pros and cons?

8 Heterogeneity For Multicast Domain A Domain B Domain C Internet Source Receiver 1 Receiver 2 AccessSW AccessSW Gateway Ethernet Telephone networks Receiver 3 64 kb/s 1 Mb/s 256 kb/s Network heterogeneity Receiver heterogeneity What Quality?

9 Outline Challenges for quality video transport An architecture for video streaming – –Video compression – –Application-layer QoS control – –Continuous media distribution services – –Streaming server – –Media synchronization mechanisms – –Protocols for streaming media Summary

10 Architecture for Video Streaming

11 Video Compression Layered Coder D D D + + Layer 0 Layer 1 Layer 2 1 Mb/s 256 kb/s 64 kb/s Layered video encoding/decoding. D denotes the decoder.

12 Application of Layered Video Domain A Domain B Domain C Internet Source Receiver 1 Receiver 2 AccessSW AccessSW Gateway Ethernet Telephone networks Receiver 3 64 kb/s 1 Mb/s 256 kb/s IP multicast

13 Application-layer QoS Control Congestion control (using rate control): –Source-based, requires rate-adaptive compression or rate shaping –Receiver-based –Hybrid Error control: –Forward error correction (FEC) –Retransmission –Error resilient compression –Error concealment

14 Congestion Control Window-based vs. rate control (pros and cons?) Window-based controlRate control

15 Source-based Rate Control

16 Video Multicast How to extend source-based rate control to multicast? Limitation of source-based rate control in multicast Trade-off between bandwidth efficiency and service flexibility

17 Receiver-based Rate Control Domain A Domain B Domain C Internet Source Receiver 1 Receiver 2 AccessSW AccessSW Gateway Ethernet Telephone networks Receiver 3 64 kb/s 1 Mb/s 256 kb/s IP multicast for layered video

18 Error Control FEC – –Channel coding – –Source coding-based FEC – –Joint source/channel coding Delay-constrained retransmission Error resilient compression Error concealment

19 Channel Coding

20 Delay-constrained Retransmission

21 Outline Challenges for quality video transport An architecture for video streaming – –Video compression – –Application-layer QoS control – –Continuous media distribution services – –Streaming server – –Media synchronization mechanisms – –Protocols for streaming media Summary

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23 Continuous Media Distribution Services Content replication (caching & mirroring) Network filtering/shaping/thinning Application-level multicast (overlay networks)

24 Caching What is caching? Why using caching? WWW means World Wide Wait? Pros and cons?

25 Outline Challenges for quality video transport An architecture for video streaming – –Video compression – –Application-layer QoS control – –Continuous media distribution services – –Streaming server – –Media synchronization mechanisms – –Protocols for streaming media Summary

26 Streaming Server Different from a web server – –Timing constraints – –Video-cassette-recorder (VCR) functions (e.g., fast forward/backward, random access, and pause/resume). Design of streaming servers – –Real-time operating system – –Special disk scheduling schemes

27 Media Synchronization Why media synchronization? Example: lip-synchronization (video/audio)

28 Protocols for Streaming Video Network-layer protocol: Internet Protocol (IP) Transport protocol: – –Lower layer: UDP & TCP – –Upper layer: Real-time Transport Protocol (RTP) & Real-Time Control Protocol (RTCP) Session control protocol: – –Real-Time Streaming Protocol (RTSP): RealPlayer – –Session Initiation Protocol (SIP): Microsoft Windows MediaPlayer; Internet telephony

29 Protocol Stacks

30 Summary Challenges for quality video transport – –Time-varying available bandwidth – –Time-varying delay – –Packet loss An architecture for video streaming – –Video compression – –Application-layer QoS control – –Continuous media distribution services – –Streaming server – –Media synchronization mechanisms – –Protocols for streaming media