An Implementation of ROS Scheme for Video Broadcasting over a Single Channel

• Main Authors: Hsiang-Wei Chen, 陳祥維
• Other Authors: Chen-Chiung Hsieh
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/90712962931086137230

碩士 === 大同大學 === 資訊工程學系(所) === 100 === The existing video-on-demand (VOD) techniques usually dedicate a bandwidth to a single user, and this is not only using the bandwidth inefficiently but also increasing the waiting time when multiple users are simultaneously raising the same demand for the service and the bandwidth would become insufficient. And with a longer waiting time, the users would be less motivated to watch the video. Therefore, how to utilize the limited bandwidth to serve more users has always been the subject of academic and industry studies. Broadcasting has always been one of the most effective techniques for VOD applications. Traditional broadcasting systems broadcast segments of a video periodically on different channels simultaneously. In this paper, we have developed a broadcasting based VOD on a single channel with low waiting time and low buffer requirement. This system will utilize the movie's popularity to determine how much bandwidth is needed to broadcast the video, designed according to our broadcasting algorithm “Reverse-order Scheduling (ROS)” method. It provides a low latency, low buffer requirements, and low cost system, and a practical application for the existing IPTV architecture, which provides users with popular video broadcasting services. With our system, users can obtain video on demand and other services with terminal units, such as computers and set top box, without worrying about a very long waiting time. The ROS method firstly partitions the video into equal-length segments, then divides these segments into groups, and finally broadcasts the segments in the same group over the same sub-channel in the reverse order of their indices. In accordance with our experiment analysis, we have been able to reduce the user's buffer requirements to 36%. When the bandwidth is up to 3b (b for consumption rate), we use 300(sec), 600(sec), and 900(sec) length videos for experiment, and get the average waiting time of 24(sec), 47(sec), and 70(sec), while the maximum buffer size requirement at 28%, 36%, and 29%. We also tested the waiting time in multi-users environment with 2 to 5 clients connecting to the server, and proved the feasibility of the system.