Optimal server bandwidth for mobile video on demand

Multimedia services such as video-on-demand or Internet protocol television in mobile environments have established themselves in our daily lives, yet the obtained quality of service still leads to many open issues. One of them consists in minimizing the server bandwidth, and we recently proposed a novel patching scheme for transporting true video-on-demand called Hierarchical Patching, which minimizes the server bandwidth. In this paper, we present a new concept called Low Start, consisting of encoding the first part of a movie with a lower bitrate than the rest. In Hierarchical Patching, video parts at the beginning have a much higher probability to be transmitted than parts at the end. By using Low Start, we show that the overall server bandwidth can be drastically reduced. We furthermore investigate the impact of Low Start on the subjective quality of service as perceived by human observers, and show that, for mobile video, the optimal strategy is to encode a very short start time with a bandwidth as low as possible.