An Alternative Scattered Pattern for Flexible Macroblock Ordering in H.264/AVC

Spatial error concealment methods in block-based video codecs use information from surrounding macroblocks to repair lost macroblocks. Using the slice group tool of H.264/AVC, it is possible to encode the macroblocks of a frame based on a scattered pattern, hereby allowing an encoder to actively help concealment methods at the decoder side. In this paper, the requirements for such a pattern are presented. Two commonly used patterns are verified against those requirements and an alternative scattered pattern is presented. Experiments show that our alternative pattern outperforms the old scattered patterns by up to 1.5 dB in case two or more slice groups are lost.