TranScaling: a video coding and multicasting framework for wireless IP multimedia services

Abstract

The convergence of the Internet with new wireless and mobile networks is creating a whole new level of heterogeneity in multimedia communications. This increased level of heterogeneity emphasizes the need for scalable and adaptive video solutions both for coding and transmission purposes. However, in general, there is an inherent tradeoff between the level of scalability and the quality of scalable video streams. In other words, the higher the bandwidth variation, the lower the overall video quality of the scalable stream that is needed to support the desired bandwidth range. In this paper, we introduce the notion of TranScaling (TS) which is a generalization of (non-scalable) transcoding. With transcaling, a scalable video stream, that covers a given bandwidth range, is mapped into one or more scalable video streams covering different bandwidth ranges. Our proposed TS framework exploits the fact that the level of heterogeneity changes at different points of the video distribution tree over wireless and mobile Internet networks. This provides the opportunity to improve the video quality by performing the appropriate transcaling process. We argue that an Internet/wireless network gateway represents a good candidate for performing transcaling. Moreover, we describe Hierarchical TranScaling (HTS) which provides a "Transcalar" the option of choosing among different levels of transcaling processes with different complexities. We illustrate the benefits of transcaling by considering the recently developed MPEG-4 Fine-Granular-Scalability (FGS) video coding. Simulation results of video transcaling are also presented.