Streaming Video over the Internet

1
Streaming Video over the Internet

• Dapeng Wu
• Electrical Computer Engineering
• University of Florida

2
What is Streaming Video?
Receiver 1

• Download mode no delay bound
• Streaming mode delay bound

Access SW
Domain B
Domain A
Data path
Domain C
Access SW
Internet
Source
Receiver 2
RealPlayer
cnn.com
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
Receiver
No bandwidth reservation
Access SW
Domain B
Rgt56 kb/s
Domain A
Data path
Rlt56 kb/s
56 kb/s
RealPlayer
Source
cnn.com
5
Time-varying Delay
Receiver
Access SW
RealPlayer
Domain B
Domain A
Data path
Delayed packets regarded as lost
56 kb/s
Source
cnn.com
6
Effect of Packet Loss
Receiver
No packet loss
Access SW
Domain B
Domain A
Data path
Loss of packets No retransmission
Source
7
Unicast vs. Multicast
Multicast
Unicast
Pros and cons?
8
Heterogeneity For Multicast

• Network heterogeneity
• Receiver heterogeneity

Receiver 2
256 kb/s
Access SW
What Quality?
Domain B
Domain A
Domain C
Internet

Gateway
Ethernet
Telephone networks
1 Mb/s
Source
Receiver 1
Receiver 3
64 kb/s
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
Layer 0
64 kb/s
Layer 1
256 kb/s
Layered Coder
Layer 2
1 Mb/s
Layered video encoding/decoding. D denotes the
decoder.
12
Application of Layered Video
Receiver 2
256 kb/s
IP multicast
Access SW
Domain B
Domain A
Domain C
Internet

Gateway
Ethernet
Telephone networks
1 Mb/s
Source
Receiver 1
Receiver 3
64 kb/s
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 control
Rate 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
IP multicast for layered video
Receiver 2
256 kb/s
Access SW
Domain B
Domain A
Domain C
Internet

Gateway
Ethernet
Telephone networks
1 Mb/s
Source
Receiver 1
Receiver 3
64 kb/s
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

22
(No Transcript)
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