H.264/AVC影像傳輸其錯誤回復與失真式錯誤保護之研究

Investigation of Lossy Error Protection for Error-Resilient H.264/AVC Video Transmission

林孟輝(Meng-Hui Lin)

指導教授 ： 陳文進

國立臺灣大學/電機資訊學院/資訊工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01741

摘要

本論文探討H.264/AVC視訊於無線網路上傳輸時的錯誤保護。基於近來分散式視訊編碼(distributed video coding)與Wyner-Ziv問題的研究成果，我們實作與探討失真式錯誤回復技術，可以有效對抗網路錯誤造成的視訊品質損失。我們以Wyner-Ziv編碼的概念來重建與保護視訊之波形，當網路錯誤率上升時，此失真式錯誤保護機制能提供平順退化的畫面品質，不會產生明顯的畫面瑕疵，以達到令人愉快的畫面觀看。另外，面對多變的網路變化，我們亦結合網路調適機制，動態地最佳化錯誤保護機制，以保證穩定的畫面品質。
實驗結果證明，此失真式錯誤保護機制能在廣泛封包遺失率範圍內保證與提供可接受且視覺平順的視訊品質。我們也證實，結合了網路調適機制，此失真式錯誤保護機制可以提供平順視訊品質調整與更穩定的保護能力。

關鍵字

錯誤回復 ； 影像傳輸

並列摘要

Recent research efforts on distributed video coding and Wyner-Ziv problems have revealed an exciting, new possibility for video applications. The Wyner-Ziv coding paradigm has suggested a novel protection scheme that can effectively combat packet losses. In this thesis, we investigate the application of lossy error protection for H.264/AVC video streaming over wireless network. Video waveforms are protected using the Wyner-Ziv coding concept, resulting in graceful video quality degradation in the presence of increasing network error rate. In addition, we propose a feedback-based network adaptation algorithm to dynamically optimize the performance of error protection in the presence of changing network dynamics.
In our design, we have applied the systematic error protection framework to the baseline H.264/AVC video stream. The systematic portion consists of unprotected video bitstream. At the same time, the Wyner-Ziv encoder generates the second, coarser representation of the unprotected, original video bitstream at much lower rate than the original. Then, the Wyner-Ziv decoder utilized the side information from the video decoder to reconstruct the coarse video waveform. When network packets are lost, the erroneous video frame can be recovered by the coarse video waveform. As a result, the video distortion caused by network packet loss is bounded by the Wyner-Ziv description. The Wyner-Ziv decoder also sends feedback messages to the Wyner-Ziv encoder; then the Wyner-Ziv encoder can adapt to varying network condition and achieve graceful video quality degradation.
Based on our experimental results, we have shown that lossy error protection can provide acceptable, eye-pleasing video quality over a large range of packet loss rates. When combining with our network adaptation algorithm, we have shown that the lossy error protection scheme can be further enhanced to provide smooth quality adaptation for H.264/AVC video transmission over wireless network.

並列關鍵字

H.264 ； error resilient coding ； video streaming

參考文獻

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