JCTVC-M0426 Non-SCE3: Cross-check of Simplified Generalized Combined Prediction Test2 (M0222, test2) [Wonkap Jang, Adeel Abbas (Vidyo??)] [late] [miss]
JCTVC-M0241 Non-SCE3: Crosscheck MTK's proposal [X. Li (Qualcomm)] [late]
JCTVC-M0275 Non-SCE3: Simplified Generalized Residual Prediction [X. Li, J. Chen, K. Rapaka, M. Karczewicz (Qualcomm)]
This document reports additional results of generalized residual prediction (GRP). To further reduce the bandwidth requirement of GRP, two variants, i.e., GRP with 3-tap up-sampling/smoothing filter and GRP with further constraint on block size, are proposed. It is reported that the computational complexity (in terms of the numbers of multiplications and additions) and memory access of GRP decoding module in the worst case is kept lower than that of motion compensation module in HEVC single layer decoding according to AHG17 template. The average luma BD-rate reduction (the average of RA cases, LD-P cases, and LD-B cases) is reported as 2.0%, 5.3%, and 3.1% for GRP with 3-tap filter and 2.0%, 5.3%, and 3.1% for GRP with additional block size constraint, respectively.
wWorst-case memory bandwidth 90-98% of SHM (if GRP is always used); same with computational complexity.
Average gain 3.4/3.5% (averaging RA,LD-P and LD-B).
Three additional modes.
Fast algorithm used for encoder speedup.
Question: Could similar simplifcations be used in refidx approach? Certainly yes for upsampling, but with high-level only changes it would not be possible to use bilinear interpolation in EL motion comp.
JCTVC-M0222 and JCTVC-M0275 to be further studied in CE: Test number of modes, GRP in chroma? various constraints that would impact computations/membandwidth vs. compression.
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