- 學位論文
無線網狀網路下之可調式多視角影像串流頻寬適應策略
Adaptive Bandwidth Methodology for Scalable Multi-view Video Streaming in Wireless Mesh Network
摘要
由於影像技術的發展，高畫質2D視訊、環景視訊及3D視訊等新技術比傳統2D影像擁有更大的資料量，因此在傳輸影像資訊時頻寬也必須提升。當頻寬不足時，視訊無法即時傳輸到客戶端，會造成畫面的延遲甚至畫面遺失；當頻寬足夠時，若可傳輸的資料量預設值太小，則會造成視訊品質不佳，頻寬使用率下降。H.264/SVC視訊壓縮編解碼格式雖然具有多層編碼的特性，提供空間、時間、品質三種可調式，但其只針對單視角影像，應用在多視角影像時，會有編碼效率差、需多次解碼等問題。H.264/MVC視訊壓縮編解碼格式能夠有效壓縮多視角影像，只需一次解碼即可得到所有視角影像，但由於缺乏空間、時間、品質三種可調性，當頻寬不穩變動時適應性差。在無線網路環境中，由於網路頻寬較有線網路小，而且影像資訊資料量大，因此如何提高頻寬的使用效率更顯重要。本論文以多視角視訊編碼技術為基礎，並加入可調式視訊編碼的時間及品質之可調式概念，提高多視角視訊的頻寬適應性，並提出頻寬適應策略，可在無線網狀網路環境中有效利用頻寬進行影像資訊傳輸。透過實驗證明，在單一用戶端時，本論文提出之策略可提供90%以上的頻寬使用率；在多用戶端時，本論文提出之策略可提供88%的頻寬使用率。
並列摘要
Due to the development of image technology, the amount of data of High-definition 2D video, full view video, and 3D video are more than traditional 2D video, the bandwidth to transfer video data also have to increase. When bandwidth is not insufficient, it may result in delay and loss screen because video data can't be immediately sent to the client. When the bandwidth is sufficient, if the default is too small amount of data transferred, it will result in poor video quality and bandwidth utilization decreased. Although H.264/SVC has the characteristics of the multi-layer coding and provides spatial, temporal and quality scalability, it focuses on single view video and has the question of compression ratio, decoding times and bandwidth allocation extended to multi-view video. H.264/MVC compresses multi-view video efficiently, can get all of view video by decoding once, and provides view scalability. Compares with H.264/SVC, H.264/MVC lacks spatial, temporal and quality scalability and has poor adaptability to unstable changes of network bandwidth. Because of the bandwidth in wireless network is less than wired, and the amount of data of video is tremendous, therefore it is more important to rise the bandwidth utilization. The system in this paper is based on multi-view video coding, and joins temporal and quality scalability in scalable video coding, improves the bandwidth adaptability of multi-view video streaming, and this paper proposes the adaptive bandwidth methodology, which is useful to utilize the limited bandwidth for video transmission in wireless network. Experiments show that, it provides more than 90% of bandwidth utilization for only one client, and it provides 88% of bandwidth utilization for multiple clients.