Hmmm.... I'm not very versed in video encoding technology but from what I gather x264 has been adding features outside of the 'official specs' for pretty much all it's existance, and looking at the list I directly recognize things like higher bit depth and cabac from x264 settings.
So I'm wondering is there some new sercet sause in h265 which makes it really much better than say x264 or is it just a new standard created around extra features which encoders like x264 already has implemented?
H265 has some quite innovative features (over H264), for instance instead of dividing the picture into rows of macroblocks, it's divided into quadtrees, which allow the compression algorithms to make more use of spatial similarity.
As far as I can tell they just amped up similar features from h.264. Better motion estimation, more block types in B-frames, etc. Just "more" of the same. edit: from that link I posted larger block sizes, larger transform sizes, fancier interpolation filters, improved intra prediction schemes, improved motion vector prediction, increased internal bit depth, new entropy coding schemes, and so forth.
x264 does not break spec. It looks familiar because H.265 is a very incremental improvement over H.264. I suspect the biggest single difference is the larger transform sizes.
So I'm wondering is there some new sercet sause in h265 which makes it really much better than say x264 or is it just a new standard created around extra features which encoders like x264 already has implemented?