1. Introduction
With steady growth of access bandwidth, more and more Internet applications start to use streaming audio and video contents [1] [2]. Since the Internet is inherently a heterogeneous and dynamical best-effort network, channel bandwidth usually fluctuates in a wide range from bit rate below 64kbits/s to well above 1Mbits/s. This brings great challenges to video coding and streaming technologies in providing a smooth playback experience and best available video quality to the users. To deal with the network bandwidth variations, two main approaches, namely, switching among multiple non-scalable bitstreams and streaming with a single scalable bitstream, have been extensively investigated in recent years.