可調適視訊壓縮串流在WIMAX之低視訊延遲回報機制設計

Abstract

可調視訊編碼(SVC)是一種可以針對播放設備以及網路頻寬，彈性的調整傳送出去位元流的影像壓縮技術，微波存取全球互通(WIMAX)是無線通訊上的新技術，我們的研究目的在於結合可調視訊編碼與微波存取全球互通的特性，在即時視訊傳送端提出一個系統上跨層的設計方法，以減少頻寬變動與無線通道品質的干擾，讓可調視訊編碼的播放端可以流暢的播放視訊影像。 在本論文中，我們提出一個跨層的設計架構以及提出一個頻寬回報機制，這個頻寬回報機制將會根據最新的頻寬訊息，決定出一個最適合未來一段時間的估計頻寬，回報給可調視訊編碼應用層，進而調整所要傳送的位元流。利用我們所提出的跨層架構以及頻寬回報機制來傳送即時視訊影像,將會在播放延遲、頻寬使用率以及資料緩衝區所累積的資料大小有著不錯的表現.

Scalable video coding (SVC) is a video compression technique which provides flexible bitstream extraction according to device types and network bandwidth, and WIMAX is a new wireless communication technique. Combining the two techniques to transmit multimedia information is an important application in the future. Our research goal is to reduce the impact of the variation of network bandwidth and channel condition on real time video communication based on above newly developed techniques. In our thesis, we propose a cross-layer architecture between SVC system and WIMAX MAC, and we also propose a mechanism to decide the bitrate of the extracted SVC bitstream. According to the latest bandwidth information, this mechanism could decide a proper bitrate to fit the bandwidth of a period in the future, and then feedback this bitrate to SVC extractor. Thus SVC extractor can extract the proper size of SVC bitstream to transmit. Finally, with the proposed architecture and mechanism, we can achieve good performance in video latency, bandwidth utilization, and buffer condition during the real time video transportation.