1. A method of resizing digital video, the method comprising: converting a group of first macroblocks in a first video frame having a first spatial resolution into a second macroblock in a corresponding second video frame having a second spatial resolution smaller than the first spatial resolution; ranking intra modes in an output basis set of intra modes based on intra modes used in the group of first macroblocks and on intra-mode transcoding statistics gathered from downsizing a training set of video frames from the first spatial resolution to the second spatial resolution; identifying a set of one or more candidate intra modes for the second macroblock based on the ranking, wherein the identified set is smaller than the output basis set; selecting an intra mode for intra-mode-prediction coding of the second macroblock from the identified set; applying the intra-mode-prediction coding to the second macroblock using the output basis set; and determining a transition-probability matrix from said downsizing the training set of video frames, wherein the transition-probability matrix is a representation of the intra-mode transcoding statistics for use in the step of ranking.