| Summary: | 碩士 === 國立高雄應用科技大學 === 電子工程系 === 98 === IPTV technology was one of the most popular and fast developed applications in recent days. IPTV was more and more concerned because it provided much more multimedia and information service for users and also offered much more user interface. The service contents in IPTV were mainly multimedia types. Too much delay and packet loss occur during transportation might result in sudden service break when users are enjoying in IPTV service, and further affect the quality of IPTV. Therefore, we implement an IPTV video on demand system consist of the IPTV video on demand system and the live system, and also provide the dynamic bandwidth detection mechanism and the seamless video stream switching mechanism to guarantee their qualities of service. The users will be able to select the video streams and live channels they need by IPTV video on demand system. During the process of watching video stream contents, the dynamic bandwidth detection mechanism will be started to detect the size of available bandwidth between the clients and multimedia servers. The clients could request different quality of video streams from the multimedia servers according to the size of available bandwidth. Requesting higher quality of video streams if the available bandwidth is abundant; otherwise, requesting lower quality of video streams while the available bandwidth goes down. Even the degradation of bandwidth was occurred, the users could watch the video stream contents contiguously according to this mechanism. However, there were only a few differences in the quality of video contents. It might course delay in playing video when switching between different qualities of video streams. Therefore, we proposed the seamless video streams switching mechanism to guarantee there will be no effect in playing video streams while switching between different qualities of video streams. We utilized the pre-loading approach in this issue which proceeded switching after accomplishing the pre-loading process to achieve the objective of seamless switching. It was able to effectively enhance the quality of service of IPTV video on demand system via the guaranteed quality of service mechanism we proposed and its implementation in our study.
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