隨著無線寬頻技術的進步與視訊壓縮標準的改進、SoC製程與效能的提升，現今可攜式裝置計算效能越來越強，可執行的功能日趨多元。許多應用都可以放在裝置上面執行，並透過無線傳輸的方式來執行許多即時的多媒體串流服務，例如視訊會議、網路電視、遠端監控等。由於許多串流應用過去大部分都在固定桌上電腦與有線的網路環境，因此在可攜性、移動性與成本等方面受到限制，若搭配支援無線環境之嵌入式平台及軟體系統設計方案將可解決這些問題，如此也可以提供使用者透過可攜式裝置不受拘束地移動來享受串流服務。
本研究將專注於在雙核心可攜式平台裝置之上，建構由視訊串流子系統、視訊解碼子系統與移動性管理子系統所組成的無線視訊串流系統設計雛型，並探討各子系統之間的設計與介面整合的實作。在視訊串流子系統部分採用最新的影像壓縮標準H.264/AVC與搭配即時傳輸協定來傳輸及接收預先錄製或即時擷取的影像，而視訊解碼子系統部份則利用雙核心平台架構設計之解碼器來做視訊資料解碼，至於移動性管理子系統的支援與整合則採用SIP協定的移動管理機制，使移動之後視訊串流仍能不間斷地播放。透過此三個子系統與其細部的元件設計與分配，將可以充分利用由數位訊號處理器(DSP)與搭配一顆主處理器(MPU)所組合而成的雙核心應用平台裝置，其具有高效能與低功耗之特性，非常適合運用在可攜式行動裝置上。最後，將實作並詳細說明整個系統間的整合設計，以及探討在做視訊串流傳輸時可能遭遇到有關封包遺失與影像品質補償的相關問題和解決方法。

With the development of high bandwidth wireless technology, video codec improvement, SoC process upgrade and performance increase, portable device has become more powerful in computation with multipurpose in application today. Many applications can be executed in portable device, and do a lot of real time streaming service, such as "Video Conference", "IP TV", and "Remote Surveillance". Many streaming applications executed on desktop computer with wired network in the past, it is limited in portability, mobility and cost. The above problems can be solved by using wireless embedded platform and software design. Therefore, it provides the user to enjoy streaming services anywhere.
The focus of this research is system prototyping for dual-core portable device to construct video streaming system in wireless environment. This system prototyping of streaming system consists of video streaming subsystem, video decoding subsystem and mobility subsystem. We will discuss the design and implementation of each subsystem and interface between subsystems in detail. Video streaming subsystem is mainly used to transmit and receive pre-recorded video or live event through “Real-Time Transport Protocol”, which adopts the newest video compression standard called “H.264/AVC”. Video decoding subsystem is mainly used to decode compressed video data through H.264/AVC decoder on dual-core platform. Mobility subsystem is mainly used to support mobility through “Session Initiation Protocol”, and this subsystem keeps ongoing video streaming despite handoff. By using three subsystems and its component-based design will achieve the maximum utilization of dual-core application platform which consists of MPU and DSP. The platform provides high computation power and low power consumption to enable richer multimedia capabilities in portable device. Finally, we will not only implement and explain the overall system prototyping design between subsystems but also discuss the related problems and solutions in video transmission and video quality, such as loss detection and concealment techniques.

[1]Joint Video Team of ITU-T and ISO/IEC JTC 1, “Draft ITU-T Recommendation and Final Draft International Standard of Joint Video Specification (ITU-T Rec. H.264 | ISO/IEC 14496-10 AVC),” Joint Video Team (JVT) of ISO/IEC MPEG and ITU-T VCEG, JVT-G050, March 2003.
[2]J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley and E. Schooler, “SIP: Session Initiation Protocol”, RFC 3261, June 2002.
[3]H. Schulzrinne, S. Casner, R. Frederick and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", RFC 3550, July 2003.
[4]Schulzrinne H, Rao A, Lanphier R, “Real Time Streaming Protocol (RTSP).”, RFC 2326, April 1998.
[5]M. Handley and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998.
[6]PAC SoC Platform White Paper, December 2004.
[7]RealView Platform Baseboard for ARM926EJ-S User Guide.
[8]Sourcery G++ (GNU Toolchain for ARM Processors), http://www.codesourcery.com/gnu_toolchains/arm.
[9]Simple DirectMedia Layer,http://www.libsdl.org.
[10]T. Wiegand, H. Schwarz, A. joch, and F. kossentini,“Rate-Constrained Coder Control and Comparison of Video Coding Standards,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 13, pp. 688-730, July 2003.
[11]T. Stockhammer, M.M. Hannuksela, and T. Wiegand, ”H.264/AVC in Wireless Environments,” IEEE Transactions on Circuits and Systems, vol. 13, no. 7, July 2003.
[12]H.264 and MPEG-4 Video Compression, Video Coding for Next-generation Multimedia, Iain E.G. Richardson.
[13]H. Schulzrinne and S. Casner, “RTP profile for audio and video conf. with minimal control,” IETF, June 2003, RFC 3551.
[14]James F. Kurose, Keith W. Ross, Computer Networking – A Top-Down Approach Featuring the Internet 2nd edition, Addison-Wesley Professional,July 2002.
[15]H. Schulzrinne and E. Wedlund, "Application-layer mobility using SIP," IEEE Service Portability and Virtual Customer Environments, pp. 29-36, December 2000.
[16]VideoLAN developers web site, “x264 - a free h264/avc encoder”, Available: http://developers.videolan.org/x264.html.
[17]Video4Linux Kernel API Reference v0.1, http://www.linuxtv.org/downloads/video4linux/API/V4L1_API.html.
[18]S. Wenger, “RTP Payload Format for H.264 Video,”Internet Engineering Task Force, RFC 3984, February 2005.
[19]T. Wiegand, G. J. Sullivan, G. Bjontegaard, A. Luthra,“Overview of the H.264/AVC Video Coding Standard,”IEEE Trans. Circuits Syst. Video Technol.Vol 13, no7, July 2003.
[20]Jorn Ostermann,Jan Bormans and Peter List etc..Video coding with H.264/AVC:tools, performance, and complexity[J].Circuits and Systems Magazine, IEEE Volume 2004,4(1):7-28.
[21]Stephan Wenger,“H.264/AVC Over IP,” IEEE Trans. Circuits Syst. Video Technol., vol 13, no. 7, July 2003.
[22]T. Stockhammer, M. M. Hannuksela, and T. Wiegand, “H.264/AVC in wireless environments” IEEE Trans. Circuits Syst. Video Technol., vol. 13, pp. 657–673,July 2003
[23]Zhi-Gang Li, Zhao-Yang Zhang,“Real-time Streaming and Robust Streaming H.264/AVC Video,” IEEE Image and Graphics, 2004. Proceedings. Third International Conference on 18-20 Dec. 2004 Page(s):353-356
[24]A. Argyriou, V. Madisetti, “Streaming H.264/AVC Video over the Internet,”IEEE Consumer Communications and Networking Conference, Jan. 2004.
[25]VideoLAN media player, http://www.videolan.org.
[26]Shau-Yin Tseng, Chih-Hao Chang, Tien-Wei Hsieh“Multimedia Programming on PAC SoC Platform”SoC Technical Journal., vol 2, May,2005
[27]Jian-Liang Luo, “The implementation and optimization of H.264 baseline profile decoder on PACDSP dual core platform,” Master Thesis, Institute of Computer Science, National Tsing Hua University, 2006.
[28]YUV 4:2:0 Video Sequences, http://trace.eas.asu.edu/yuv/index.html.