An Adaptive Deblocking Filter for ROI-Based Scalable Video Coding

The Region-of-interest (ROI) based video coding within Scalable Video Coding (SVC) can be implemented by making use of Type 2 Flexible Macroblock Ordering (FMO), which marks independent rectangle regions/slices inside a frame by their top-left and bottom-right coordinates. By employing the proposed scheme, a displaying frame can be separated into several independent regions that are assigned with different Signal-Noise-Ratio (SNR), Spatial and Temporal quality. The scheme can be used to ensure the achievement of high sub-jecitve quality or to fulfill some special functionalities. Owning to the fact that the frame is separated into independent regions, and the regions are assigned with big quality differences, false edge (blockiness) may appear around the ROI boundaries, which cannot be automatically removed by the in-loop filters. The annoyance of such artifact depends on the local visual context, thus a new adaptive deblocking filter is proposed in this paper. The filter includes two steps: first, the complexity of the blocks around ROI boundaries is measured; and different filtering modes and smoothing abilities are then selected accordingly to reduce the annoyance of the blockiness. Experimental results showed that coding quality is improved by the proposed filter in low bitrate Coarse Granular Scalability (CESB) video.