a video compression process speeds the optimal choice of quantizers for compressing a data stream by setting up the optimization problem as a path - optimization problem in configuration space and finding the lowest cost path through the configuration space . the process begins with a starting node and propagates least - cost waves through the space until a path is completed to the end . the process may continue using uncompleted paths while their costs are less than the end state , beginning with the lowest cost incomplete path , until an improved path is found . the process may further continue , for a time constrained process , until time runs out or all useful possibilities are exhausted .