Broadcasting protocols are proved to be efficient for transmitting most of the popular videos in video-on-demand systems. We propose a generalized analytical approach to evaluate the efficiency of the broadcasting protocols and derive the theoretical lower bandwidth requirement bound for any periodic broadcasting protocols. By means of the proposed analytical tool-temporal-bandwidth map, the approach can be used to direct the design of periodic broadcasting protocols to achieve different goals, e.g., server bandwidth requirement, client waiting time, client I/O bandwidth requirement etc. As the most important performance index in a VOD system is the required server bandwidth, we give the solution to achieve the optimal bandwidth efficiency given client waiting time requirement and the length of the video. To take into account the popular compressed video with variable bit rate, the optimal approach is applied readily to the VBR videos and can achieve zero loss and best bandwidth efficiency. We give a proof why existing techniques such as smoothing and prefetching is not necessary and in some cases inefficient in broadcasting protocols. We also discuss how broadcasting schemes can be tailored to support true and interactive VOD service. An insightful comparison between broadcasting and multicasting schemes is also given.

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In order to address the scalability problems of video-on-demand systems, several periodic broadcast schemes have been proposed that partition a video into segments and repetitively broadcast each segment on a separate channel. A new scheme is presented for the bandwidth-efficient periodic broadcast of video. The proposed scheme determines the segment sizes and their corresponding channel bandwidths as a result of a non-linear optimization problem which minimizes the total required bandwidth for the broadcast. The new scheme outperforms the existing schemes in terms of bandwidth demands while it also decouples the playout latency from the number of available channels. Further analysis reveals that its asymptotic bandwidth requirements exactly match the asymptotic bandwidth requirements reported for poly-harmonic broadcasting.