Intra prediction modes are tailored to exploit spatial redundancy. There is a tendency to increase the number of intra-prediction modes for each new video standard.
Number of intra-prediction modes per video standard:
H261 0
H264/AVC 9
H265/HEVC 35
H266/VVC ~65
I think in the context of coding efficiency the optimal number of intra modes should be in the range [30 ..60].
If the number of intra prediction modes exceeding 60 then the coding efficiency is deteriorated due to allocation of additional bits to signal the mode index.
Moreover, encoding times are increased since search area of optimal mode is inflated.
23+ years’ programming and theoretical experience in the computer science fields such as video compression, media streaming and artificial intelligence (co-author of several papers and patents).
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