Scalable Video Transcaling for the Wireless Internet
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Scalable Video Transcaling for the Wireless Internet Hayder Radha Department of Electrical and Computer Engineering, Michigan State University, MI 48824-1226, USA Email: [email protected]
Mihaela van der Schaar Department of Electrical and Computer Engineering, University of California, Davis, CA 95616-5294, USA Email: [email protected]
Shirish Karande Department of Electrical and Computer Engineering, Michigan State University, MI 48824-1226, USA Email: [email protected] Received 5 December 2002; Revised 28 July 2003 The rapid and unprecedented increase in the heterogeneity of multimedia networks and devices emphasizes the need for scalable and adaptive video solutions for both coding and transmission purposes. However, in general, there is an inherent trade-off 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 wireless video transcaling (TS), which is a generalization of (nonscalable) transcoding. With TS, 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 TS process. We argue that an Internet/wireless network gateway represents a good candidate for performing TS. Moreover, we describe hierarchical TS (HTS), which provides a “transcaler” with the option of choosing among different levels of TS processes with different complexities. We illustrate the benefits of TS by considering the recently developed MPEG-4 fine granularity scalability (FGS) video coding. Extensive simulation results of video TS over bit rate ranges supported by emerging wireless LANs are presented. Keywords and phrases: transcoding, FGS, scalable, video, transcaling, streaming.
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INTRODUCTION
The level of heterogeneity in multimedia communications has been influenced significantly by new wireless LANs and mobile networks. In addition to supporting traditional web applications, these networks are emerging as important Internet video access systems. Meanwhile, both the Internet [1, 2, 3] and wireless networks are evolving to higher bit rate platforms with even larger amount of possible variations in bandwidth and other quality of services (QoS) parameters. For example, IEEE 802.11a and HiperLAN2 wireless LANs are supporting (physical layer) bit rates from 6 Mbps to 54 Mbps (see, e.g., [4, 5]). Within each of the supported bit rates, there are further variations in bandwidth due to the shared nature of the network and the heterogeneity of the devices and the quality of their physical connections. Moreover, wireless LANs are expected to provide higher bi
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