Video coding focusing on block partitioning and occlusions

Abstract—Among the existing block partitioning schemes, the pattern-based video coding (PVC) has already established its su-periority at low bit-rate. Its innovative segmentation process with regular-shaped pattern templates is very fast as it avoids handling the exact shape of the moving objects. It also judiciously encodes the pattern-uncovered background segments capturing high level of interblock temporal redundancy without any motion compen-sation, which is favoured by the rate-distortion optimizer at low bit-rates. The existing PVC technique, however, uses a number of content-sensitive thresholds and thus setting them to any prede-fined values risks ignoring some of the macroblocks that would otherwise be encoded with patterns. Furthermore, occluded back-ground can potentially degrade the performance of this technique. In this paper, a robust PVC scheme is proposed by removing all the content-sensitive thresholds, introducing a new similarity metric, considering multiple top-ranked patterns by the rate-distortion op-timizer, and refining the Lagrangian multiplier of the H.264 stan-dard for efficient embedding. A novel pattern-based residual en-coding approach is also integrated to address the occlusion issue. Once embedded into the H.264 Baseline profile, the proposed PVC scheme improves the image quality perceptually significantly by at least 0.5 dB in low bit-rate video coding applications. A similar trend is observed for moderate to high bit-rate applications when the proposed scheme replaces the bi-directional predictive mode in the H.264 High profile. Index Terms—Block partitioning, H.264, motion estimation, occlusion, pattern-based coding, rate-distortion optimisation, sub-blocking, uncovered background coding, video coding. I