JVET-J0050 Intra block copy improvement on top of Tencent’s CfP response [X. Xu, X. Li, G. Li, S. Liu (Tencent)]
This contribution was discussed Saturday 14 April at 1200 (chaired by JRO and GJS).
This contribution describes the technical aspects of intra block copy (IBC, a.k.a. CPR) implementation modifications on top of Tencent’s CfP response JVET-J0029. It was reported that a 0.31% luma BD rate delta relative to Tencent’s software anchor for SDR constraint set 1 (i.e., RA) was observed when IBC mode was turned off. It was also reported that a 58.49% RA luma BD rate delta was observed relative to Tencent’s software anchor for screen content test sequences in the TGM 1080p category.
The contribution has a modification that moves the signalling flag to a different position in the syntax (but does not use the reference picture list approach taken in HEVC). The IBC flag is put after the merge flag. This reportedly has some advantage for screen content (although not noticeable impact for natural content). The CfP proposal reportedly gives around 52% bit rate reduction for this type of content, whereas the modified method of signalling provides 58%. The effect is reportedly almost negligible for natural content.
See also the notes above for the related contribution JVET-J0042. Both contributions raise similar issues.