Bandwidth-Scalable video Broadcasting for VBR encoded videos with High Performance

In VOD systems, allocating more bandwidths to broadcast hotter videos, the minimal average client waiting time will be achieved. But the hot degree of videos is fluctuating dynamically, and it requires the algorithm to be scalable. According to the research of broadcasting algorithms for CBR encoded video, most of the bandwidth-effective algorithms (such as greedy equal bandwidth broadcasting (GEBB) and poly-harmonic broadcasting (PHB) etc.) use narrower channel bandwidth than the video's actual playing rate and greedy downloading method. Based on this theory, some derived high-performance algorithms for VBR encoded videos were proposed, such as FSEB, BSEB-PC, VBHB and SVBR etc. But there is no one that has the capability of changing the bandwidth dynamically at running time (which was also called channel transition). This paper presents the first algorithm named bandwidth-scalable broadcasting for VBR encoded videos (SB-VBR) which is able to dynamically shift bandwidth at running time. To get the high performance, this algorithm places the possible longest segments from the last channel to previous channels by utilizing the best bandwidth-effective algorithm model. A new method of Byte_Align for B frame is put forward in this paper in order to enhance the performance. With adoption of additional channels, the process of channel transition is transparent to clients and easier to be realized. Furthermore, this paper presents a simple method to compute the limitation of performance. Using data from real videos, we compare the total bandwidth needed by our algorithm with the theoretical minimum bandwidth and other algorithms for VBR encoded videos. The experimental results demonstrated that the algorithm is high-performance and practical.