Video data provision

Abstract

Video clips are generated from a sequence of video data for delivery and playback on demand. Each clip () is identified by an event marker () and a pre/post event ratio (PPER). The pre/post event ratio determines the relative duration of the clip before and after the element defined by the event marker. In response to a request for video clip data, identified with reference to the event marker (), the discrete elements () of video data making up each clip are allocated to a sequence starting with the element associated with the event marker () and following in an order (, etc) determined by the pre/post event ratio. This allows clips having different durations but having the same PPER to be transmitted to different receivers dependant on channel capacity or reliability. The receiver may compile clips of a selected length by compiling the elements starting at the event marker and adding the elements in a sequence, before and after the event marker, determined by the PPER until a clip of a required length is complete. A sequence of several clips can be compiled, the event markers for different clips having different priorities such that if a short sequence is required, the low priority clips are omitted or abbreviated.