JVET-R0300 Additional fix for long luma deblocking decisions [K. Andersson, J. Enhorn (Ericsson)]
The contribution proposes to fix the long deblocking decision such that all lines of respective 4 samples boundary segment are checked to avoid over filtering of lines 1 and 2 due to decision based only on line 0 and line 3. It is asserted that the proposal ensures that the deblocking filtering is robust and that the fix does not increase worst case complexity for deblocking decisions.
The BD rate impact for luma for CTC SDR:
AI: 0.00%, RA: -0.01%, LDB: -0.05%, LDP: -0.01%.
The BD rate impact for CTC HDR:
AI: DE: 0.01% PSNRL: 0.00% wPSNRY: 0.00%, PSNRY: 0.00%
RA: DE: -0.04% PSNRL: -0.03% wPSNRY: -0.02%, PSNRY: 0.00%
Similar encoding and decoding time as the anchor.
The number of operations increases, but is still less than worst case for deblocking.
The target is rather a corner case, it is reported that the effect was visible in the sequence slide editing. Other experts mentioned that deblocking for screen content is a very special case, where an encoder might want to align parameters.
It was not obvious that there is need for action on this issue.