兼具高傳輸效率與容錯韌力之異質多層次多媒體群播服務

Abstract

我們是一個以視訊壓縮、通道/網路編碼及互聯網路 (internetworking)為主題的研究團隊，提出一套可調式異質網路群播系統，，使其能夠提供在不穩定網路中的各式裝置，一種透過位元率-失最佳化而達到近似及時的視訊串流服務。 我們提出的服務藉由下面的手法達成：透過具有「適應性多途徑和非均等錯誤或遺漏更正碼」的多重樹狀應用層群播網路傳送可調式影片編碼位元的串流。使用H.264可調式影片編碼(Scalable Video Coding, SVC)標準，能夠將影像序列編碼成各層間相關的網路抽象層(Network Abstract Layer)單位並允許裝制能按自身網路頻寬與處理能力調整影像的接收與播放。另一方面，多重樹狀應用層(Application-layer multicasting)能根據各別的位元率、播放優先權與重要度，使用網路中不同的途徑傳遞不同的SVC層。而多重樹狀應用層這方面，需要提供通道/網路編碼，進而提供SVC層非均等錯誤或遺漏的保護並使用多途徑方式細分高元率的串流和部分資料接受回復的能力。ALM網路將由JXTA上實作的P2P-SIP管理，而其資料串流將由UDP/DDCP協議來達成。 我們的將致力於下列技術的革新以實現：

We, a team of researchers in video compression, channel/network coding and internetworking, propose to develop a scalable heterogeneous multimedia multicasting system that can offer rate-distortion optimized near real-time video streaming services to a wide variety of viewing devices under unstable network conditions. The proposed service will be made possible by transporting scalable video coded bitstreams through an adaptive multi-tree application-layer multicasting network that employs multipath unequal erasure protection codes. The H.264 Scalable Video Coding (SVC) standard enables video sequences to be encoded into interdependent layers of network abstraction layer (NAL) units and permits viewing devices to adapt their video reception and playback according to device capability and network performance. A multi-tree application layer multicasting (ALM) network, on the other hand, can pass different SVC layers through the Internet along different paths based on their bit rates, playback priority and importance. Finally, the ALM transport shall be supplemented with channel/network coding techniques that can provide unequal erasure protection to SVC layers and use multipath diversity to break down high-rate bit-streams and to enable data reconstruction with partial reception. The ALM network will be managed by a P2P-SIP implementation on JXTA while the data streams will be carried over UDP/DDCP protocols. To realize our goals, the project will pursue the following technology innovation: