隨著近年來行動裝置的爆發性成長，行動多媒體的應用也日漸廣泛，透過無線網路傳輸的影片串流成為現代都市人生活當中不可或缺的一環。也因為如此，提供高品質且即時的多媒體傳輸應用也成為相當重要的議題。面對不穩定的無線網路，傳輸過程中時常會有封包遺失或傳送錯誤的狀況發生。過去以來，前向糾錯機制一直被廣泛地利用在影像多媒體的串流應用上，而前向糾錯機制當中的影像品質以及傳送延遲一直是研究者們難以取捨的兩難。近年來也有許多的研究試圖在即時影像串流的應用上盡可能的提升影像畫面的品質。其中各種不同前向糾錯機制的配置都有可能讓影像品質或是延遲時間的表現有所提升。
本篇論文提出了一個動態可調性視窗的前向糾錯機制。利用可解畫面比例的運算，動態調整將多個影像畫面編作為前向糾錯機制的編碼區間，較先前的研究減少了運算的複雜度，也近一步地降低了傳送時的延遲時間。我們再利用一個滑動視窗，使得前後的編碼區塊有所重疊，而達到整體品質提升的效果。實驗的結果也證明，使用滑動視窗緩和了原有的影像顫動的現象。

The mobile devices have become explosive hits on global markets. The applications of multimedia and video streaming have a significant growth. It have become a crucial part of modern lives to view video streaming and broadcasting as well as other multimedia applications via wireless internet. To provide stable high quality multimedia instantly have therefore become an important issue to be addressed.
Data transmission through a lossy channel is in the risk of packets losses or error occurrences. Forward Error Correction (FEC) have been widely used in the area of video streaming and multimedia broadcasting. The quality performance and transmission delay have been a trade-off that troubles researchers for years to find a balance in between.
This paper proposed a Dynamic Scalable Sliding Window scheme as a novel FEC to provide higher quality of video streaming with lower delay and more stable quality compared to previous similar approaches. The scheme exploit Decodable Frame Rate (DFR) to estimate the quality expectation and dynamically adjust the FEC coding block. In addition, the sliding window algorithm overlaps one frame each time as the window slides. The simulation results indicates that, with the extra overlapped frame, the overall recovery rate is enhanced and the video fluctuation in real-time transmission is also much improved. The experimental results also shows the scheme provides higher DFR performances than previous related researches and frame-level FEC throughout varies packet loss rate.

[1] T.Wiegand, G. Sullivan, G. Bjontegaard, and A. Luthra. Overview of The H.264/AVC Video Coding Standard. IEEE Transaction Circuits System Video Technology, vol. 13, no. 7, pp. 560–576, Jul. 2003.
[2] H. Schwarz, D. Marpe, and T. Wiegand. Overview of the scalable video coding extension of the H.264/AVC standard. IEEE Transaction Circuits System Video Technology, vol. 17, no. 9, pp. 1103–1120, Sep. 2007.
[3] T. Stockhammer,M. Hannuksela, and T.Wiegand. H.264/AVC in Wireless Environments. IEEE Transaction Circuits System Video Technology, vol. 13, no. 7, pp. 657–673, Jul. 2003.
[4] K. Park and W. Wang. QoS-sensitive Transport of Real-time MPEG Video using Adaptive Forward Error Correction. IEEE Multimedia Computing and Systems, pp. 426-432, June 1999.
[5] K. Mayer-Patel, L. Le, and G. Carle. An MPEG Performance Model and its Application to Adaptive Forward Error Correction. Proceedings of ACM Multimedia, pp. 1-10, December 2002.
[6] A. Nafaa. Forward Error Correction Strategies for Media Streaming over Wireless Networks. IEEE Communications Magazine, vol. 46, pp. 72-79, Dec. 2007.
[7] S. R. Kang, and D. Loguinov. Modeling Best-effort and FEC Streaming of Scalable Video in Lossy Network Channels. IEEE/ACM Transaction on Networking, vol. 15, pp. 187-200, Feb. 2007.
[8] Cheng-Han Lin, Chih-Heng Ke, Ce-Kuen Shieh, Naveen K Chilamkurti. The Packet Loss Effect on MPEG Video Transmission in Wireless Networks. Advanced Information Networking and Applications, Vienna, vol. 1, pp. 565-572, April 2006.
[9] Yufei Yuan, Bruce Cockburn, Thomas Sikora, and Mrinal Mandal. A GoP Based FEC Technique for Packet Based Video Streaming. ICCOM Proceedings of the WSEAS international conference on Communications, pp. 187-192, 2006.
[10] Yufei Yuan; Bruce Cockburn; Thomas Sikora; Mrinal K. Mandal. Efficient allocation of packet-level forward error correction in video streaming over the Internet. Journal of Electronic Imaging, Volume 16, Issue 2, April 2007.
[11] H. Wu, M. Claypool, and R. Kinicki. Adjusting Forward Error Correction with Temporal Scaling For TCP-Friendly Streaming MPEG. ACM Transaction Multimedia Computing, Communication and Applications, vol. 1, no. 4, pp. 315–337, Nov., 2005.
[12] Ming-Fong Tsai, Naveen Chilamkurti, Ce-Kuen Shieh. A novel multi-path forward error correction control scheme with path interleaving for video transmissions. International Conference Telecommunications, St. Petersburg, pp.1-8, June 2008.
[13] E. Baccaglini, T. Tillo, and G. Olmo. Slice sorting for unequal loss protection of video streams. IEEE Signal Processing Letters, vol. 15, no. 1, pp. 581–584, Dec. 2008.
[14] A. Bouabdallah and J. Lacan. Dependency-aware unequal erasure protection codes. Journal of Zhejiang University SCIENCE A, vol. 7, no. 1, pp. 27–33, 2006.
[15] X. Yang, C. Zhu, Z. G. Li, X. Lin, and N. Ling. An unequal packet loss resilience scheme for video over the Internet. IEEE Transaction Multimedia, vol. 7, no. 4, pp. 753–765, Aug. 2005.
[16] Huai-Wen Zhang. An Enhanced Prediction-based Forward Error Correction Scheme. Institute of Computer & Communication, National Cheng Kung University, 2012.
[17] Kai Po Chuang, Wei Tsong Lee, Hsin Wen Wei. Dynamically Adjust Packet Size and Block Size to Achieve Maximum Effectiveness of Forward Error Correction. Intelligent Information Hiding and Multimedia Signal Processing, pp. 658 - 661, 2014.
[18] J. Xiao, T. Tillo, C. Lin, and Y. Zhao. Dynamic Sub-GoP Forward Error Correction Code for Real-Time Video Applications. Multimedia, IEEE Transactions on vol. 14, no. 4, pp. 1298–1308, 2012.
[19] Li Yu, J. Xiao, T. Tillo, Dynamic Redundancy Allocation for Video Streaming Using Sub-GOP Based FEC Code. IEEE Visual Communications and Image Processing Conference, pp. 518 – 521, Dec. 2014.
[20] Pasquale Cataldi, Marco Grangetto, Tammam Tillo, Enrico Magli and Gabriella Olmo. Sliding-Window Raptor Codes for Efficient Scalable Wireless Video Broadcasting With Unequal Loss Protection. IEEE Transactions on Image Processing, vol. 19, no. 6, June 2010.
[21] J. Neckebroek, M. Moeneclaey, E. Magli. Comparison of Reed-Solomon And Raptor Codes for The Protection of Video On-Demand on The Erasure Channel. Information Theory and its Applications (ISITA), pp. 856 – 860, Oct. 2010.
[22] Chih-Heng Ke, Ce-Kuen Shieh, Wen-Shyang Hwang and Artur Ziviani. An Evaluation Framework for More Realistic Simulations of MPEG Video Transmission. Journal of Information Science And Engineering 24, pp. 425-440, 2008.
[23] W. Tan and A. Zakhor. Video Multicast using Layered FEC and Scalable Compression. IEEE Transaction on Circuits System Video Technology, vol. 11, no. 3, pp. 373-386, Mar. 1999.
[24] D. Vukobratovic, V. Stankovic, D. Sejdinovic, L. Stankovic, and X. Zixiang. Scalable Video Multicast Using Expanding Window Fountain Codes. IEEE Transaction Multimedia, vol. 11, no. 6, pp. 1094–1104, Oct., 2009.