1. CIS679: MPEG-2
Review of MPEG-1
MPEG-2
Multimedia and networking

2. Review of MPEG-1 MPEG: Motion Pictures Experts Group
MPEG exploits motion prediction
Successive frames may have significantly same data
Apply motion prediction at the Macroblock level
I, P, and B frames
The standard allows the use of I-frame only, I and P frames only or I-, P- and B-frames => GOP: the number of frames/pictures between successive I-frames

3. MPEG-2 MPEG-2 strives for a higher resolution.
MPEG-1 is near the maximum data rate of about 1.5Mbits/s.
MPEG-2 targets at 40Mbits/s => high resolution.
MPEG-2 supports four levels
Low, main, high 1440 and high
There are five profiles associated with each level
The low level of MPEG-2 is compatible with MPEG-1.

5. Multimedia Applications
Video-on-demand
Near-video-on-demand
Travel/training videos
Interactive games
Teleconferencing
IP Telephony

6. Multimedia Application Classes
Streaming
Clients request audio/video files from servers and pipeline reception over the network and display
Interactive: user can control operation (similar to VCR: pause, resume, fast forward, rewind, etc.)
Delay: from client request until display start can be 1 to 10 seconds

7. Multimedia Application Classes (more)
Unidirectional Real-Time
similar to existing TV and radio stations, but delivery on the network
Non-interactive, just listen/view
Interactive Real-Time
Phone conversation or video conference
More stringent delay requirement than Streaming and Unidirectional because of real-time nature
Video: < 150 msec acceptable
Audio: < 150 msec good, <400 msec acceptable

8. Multimedia Requirements
Guarantees
Throughput and/or delay guarantees
Audio requires loss/delay guarantees
Interactive apps. require low delay
CBR & VBR
Variable bit rate places extra burden

9. Challenges to the Current Internet
TCP/UDP/IP suite provides best-effort, no guarantees on expectation or variance of packet delay
Streaming applications delay of 5 to 10 seconds is typical and has been acceptable, but performance deteriorate if links are congested (transoceanic)
Real-Time Interactive requirements on delay and its jitter have been satisfied by over-provisioning (providing plenty of bandwidth), what will happen when the load increases?...

10. Challenges to the Current Internet (more)
Most router implementations use only First-Come-First-Serve (FCFS) packet processing and transmission scheduling
To mitigate impact of “best-effort” protocols, we can:
Use UDP to avoid TCP and its slow-start phase…
Buffer content at client and control playback to remedy jitter
Adapt compression level to available bandwidth

11. Conclusion MPEG-2 Multimedia application classes
Targets at high resolution
Profiles and levels
Compatible to MPEG-1
Multimedia application classes
Streaming
Unidirectional real-time applications
Interactive real-time applications
Multimedia requirements
Challenges