DCT-based CODECs such as MPEG-4 Visual and H.263 "skip" many macroblocks during encoding of typical video sequences (i.e. no coded data is transmitted for these macroblocks). This paper describes an algorithm that predicts macroblocks that are likely to be skipped by the encoder. The algorithm estimates the increase in distortion due to not coding (skipping) each macroblock. Macroblocks that can be skipped with little or no increase in distortion are not coded, resulting in substantial computational savings without significantly affecting ratedistortion performance.
Iain E. Garden Richardson, Yafan Zhao