Robust System and Cross-Layer Design for H.264/AVC-Based Wireless Video Applications
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Robust System and Cross-Layer Design for H.264/AVC-Based Wireless Video Applications Thomas Stockhammer BenQ Mobile, Haidenauplatz 1, 81667 Munich, Germany Received 18 March 2005; Revised 30 September 2005; Accepted 4 October 2005 H.264/AVC is an essential component in emerging wireless video applications, thanks to its excellent compression efficiency and network-friendly design. However, a video coding standard itself is only a single component within a complex system. Its effectiveness strongly depends on the appropriate configuration of encoders, decoders, as well as transport and network features. The applicability of different features depends on application constraints, the availability and quality of feedback and cross-layer information, and the accessible quality-of-service (QoS) tools in modern wireless networks. We discuss robust integration of H.264/AVC in wireless real-time video applications. Specifically, the use of different coding and transport-related features for different application types is elaborated. Guidelines for the selection of appropriate coding tools, encoder and decoder settings, as well as transport and network parameters are provided and justified. Selected simulation results show the superiority of lower layer error control over application layer error control and video error resilience features. Copyright © 2006 Hindawi Publishing Corporation. All rights reserved.
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INTRODUCTION
Most of the emerging and future mobile client devices will significantly differ from those being used for speech communications only: handheld devices will be equipped with color displays and cameras and they will have sufficient processing power which allows presentation, recording, and encoding/decoding of video sequences. In addition, emerging and future wireless systems will provide sufficient bitrates to support video communication applications. Nevertheless, bitrate will always be a scarce resource in wireless transmission environments due to physical bandwidth and power limitations and thus efficient video compression is required. Nowadays H.263 and MPEG-4 Visual Simple Profile are commonly used in handheld products, but it is foreseen that H.264/AVC [1] will be the video codec of choice for many video applications in the near future. The compression efficiency of the new standard excels prior standards roughly by at least a factor of two. These advantages also introduce additional processing requirements in both, the encoder and the decoder. However, dedicated hardware as well Moore’s law will allow more complex algorithms on handheld devices in the future. Although compression efficiency is the major attribute for a video codec to be successful in wireless transmission environments, it is also necessary that a standardized codec provides means to be integrated easily into existing and future networks as well as to be usable in different applications.
A key property for easy and successful integration is robustness and adaptation capabilities to different transmission conditions. Thereby, rather than providing com
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