Video on demand over ATM: constant-rate transmission and transport

We introduce a specific transport and transmission scheme for video-on-demand called constant-rate transmission and transport (CRTT). CRTT establishes a CBR virtual channel between the video provider and the viewer's set-top box, and then transmits cells from the provider into this channel at a constant rate. Since we assume that the number of cells in a frame is variable, CRTT requires that some number of cells be built up in a set-top box buffer before the commencement of playback. The build up, cell transmission rate, and the set-top memory size must be chosen so that there is no starvation or overflow at the set-top box. We develop fundamental relationships between these parameters for viable CRTT. We then apply the theory to an MPEG encoding of Star Wars and find that the minimal set-top box memory for CRTT is 23 Mbytes. We also consider varying the constant rate over a small number of intervals. We find, for example, that for Star Wars approximately 2 Mbytes of set-top memory suffices with 32 constant-rate intervals.