Using conventional broadcasting, if we want to support a 120-minute popular movie every 10 minutes, we need 12 video channels. Suppose the set-top box at client end call buffer portions of the playing video on disk. Pyramid broadcasting schemes can reduce the bandwidth. requirements to 5.7 channels. We present a new scheme which only needs 3.2 channels. For a movie with length D minutes, if we want to reduce the viewer waiting time to D/N minutes, we only need to allocate H(N) video channels to broadcast the movie periodically. Where H(N) is the harmonic number of N, H(N)=1+1/2+...+1/N. In order to support video-on-demand service for a popular movie, the new scheme greatly reduce the bandwidth requirements.
