this document relates to video transport systems and in particular , though not exclusively , where several compressed or encoded video services are multiplexed into a fixed bit rate transmission stream . there is provided a method of allocating bit - rates for video services in a transport channel . the method comprises receiving user defined weighting parameters for a number of video services ; then determining an available bit - rate for a transport channel for the video services . the method then automatically allocates a proportion of the available bit - rate to each video service according to their respective weighting parameters ; and multiplexes the video services into the transport channel according to the allocated proportions of the available bit - rate .