2017/03/30 - (Paper) Adaptive Video Multicast over the Internet - Part 2

Survey

Authors : Jiangchuan Liu and Bo Li , Hong Kong University of Science and Technology

Published in: IEEE MultiMedia ( Volume: 10, Issue: 1, Jan-Mar 2003 )

Full text : IEEE link here.

Existing adaptation approaches for video multicast (cont.)

Agent-based adaptation

Deploy several agents in a large-scale network, and the agents partition the network into several confined regions, and each agent can thus handle the requirements more easily from its local region.

../_images/014.png

In figure (a) , an active node (such as a video gateway or agent) offers a richer set of services for video transmission at the application level than figure (b).

Support for video coding techniques

Discrete cosine transform (DCT 1) : A finite sequence of data points in terms of a sum of cosine functions oscillating at different frequencies. => Related to lossy compression of audio (e.g. MP3) and images (e.g. JPEG)

Variable bit rate (VBR) and Constant bit rate(CBR) 2 : Both terms are used to describe QoS.

Transcoding

A transcoder converts an existing video stream into a new stream with a different format or rate.

Scalable coding

Intraframe coding(I-frame),preditive coding(P-fram),and bidirectional predictive coding(B-frame). 3 => In video compression.

For a spacific enhancement layer, we have only one choice, either to enhance the temporal resolution (time->speed) and spatial resolution (space->quality).

Conclusions

  • Simulcast remains a promising approach to address user heterogeneity.=> It’s supported in many commercial streaming systems.

  • Layered multicast has seldom been used.

  • The process of decompression and lossy recompression inherently accumulates quantization noise each time.

  • Since Inhternet protocol multicast hasn’t been widely deployed, the CDN 4 provides a very attractive alternative that’s readily available for the current Internet.