Spiral coding order of macroblocks with applications to SNR-scalable video compression

Video sequences are compressed by processing individual macroblocks within frames. Traditional macroblock order of processing is linear from the left to the right, and from the top to the bottom. In this paper, an alternative order of macroblock processing is considered. Proposed is the spiral scan beginning at the centre of an image, or more general, in the centre of interest that is often placed in the centre of an image by a person who shots the video. The paper shows that such a change of processing order does not influence compression performance but it is profitable in scalable video coding where it can be used in the enhancement layers by SNR scalability. The paper provides the respective experimental results for low-complexity efficient SNR scalability with fine granularity.