2017/03/09 - (Paper) Adaptive Video Multicast over the Internet - Part 1

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.

Reading Page in this part : 1-4

Introduction

Multicast extends the traditional unicast communications and ofen called IP Multicast.

Bandwidth adaptability becomes an essential requirement for video distrubution over Interner because there’s no QoS guarantee in the current best-effort Internet.

Nonadaptive stream (Because Internet is a heterogeneous network.) :

  1. Underuse the available bandwidth or cause congestion.

  2. Unfair bandwidth allocation.

Existing adaptation approaches for video multicast

Video rates : Single rate and Multirate.

The place where adaption is performed : End system or intermediate network nodes.

Single-rate adaptation

Sender maintains one vidwo stream and adjusts the rate based on receives’ states.(Receivers detect the states.)

-> Sender will be overwhelmed with the reponses.

-> When the size groups , each receiver reduces the frequency of its RTCP report.

Although incapable of solving the problem of hetergeneity, single-rate multicast can serve as a building block for advanced video multicast protocols, such as the simulcast protocols.

Simulcast

Individual feedback-controlled connections -> bandwidth efficiency is low but it can achieve ideal fairness.

Destination Set Grouping (DSG) Protocol :

Carrying low,medinum , and high quality versions of the original video.

-> Bandwidth redundancy caused by replication.

Layered adaptation

Decomposition schema : Cumulative Layering.

  1. Base layer : Video main data.

  2. Enhancement layers : Data that refine the reconstructed video quality.

Prioritized transmission :

  1. Base layer is the highest priority.

  2. Enhancement layers have lower priorities.

-> Require routers to implement priority-based packet scheduling policy.

To be continue…

Summary

In this part of this paper, it discusses about the importance of adaptive stream.It lists the existing adaptation approaches for video multicast , such as Single rate and Simulcast , to improve bandwidth efficiency.