x265 quality is not improving

[Aludin]

Seriously, I have been testing every successive version of x265 since late 2013 hoping that quality will improve but it hasn't, in fact it has gotten slightly worse despite the new settings and despite the much slower encoding speed.
I have been told this isn't normal but I dare you to prove me wrong.

Actually, as of version 2.7 the quality has improved but only to match 1.0's levels, which means it just undid the deterioration and is still twice as slower as the version released 4 years ago.

My source is an anime clip that was frequently used to showcase x264's triumph at delivering watchable content at dialup speeds back in the day. Download link at bottom. I have tested it at bitrates of 67, 128 and 256. At 67 the quality sucks, at 128 it's good, at 256 it's almost flawless.

I'll get right to the point with the stats: (bold means it was encoded in 10-bit)

Method | Version | Filesize | SSIM+ score
2pass 1.2 1754 93.74
2pass 2.6 1757 93.55
2pass 2.9 1757 93.9
2pass 2.9 1754 93.83

Encoding speeds:
6.25 fps
2.88 fps
2.34 fps
0.92 fps

At 128 kb/s:

2pass 1.2 3330 97.62
2pass 2.6 3327 97.59
2pass 2.9 3327 97.67
2pass 2.9 3331 97.77

Encoding speeds:
4.42 fps
2.64 fps
2.35 fps
0.85 fps

At 256 kb/s:
2pass 1.2 6686 99.02
2pass 2.6 6685 98.98
2pass 2.9 6686 99.01

Didn't record encoding speeds for 256 kb/s.

Files attached. I BEG YOU TO PROVE ME WRONG. I had this discussion with Selur a year ago and he fell silent.

Note that if you're gonna do an encode, make sure you use the same number of --refs, bframes and lookahead as I did. This isn't about artificially limiting x265 so much as making it not take forever to get a simple test over with. I'm well aware using 16 refs will dramatically increase quality and I'd do it in a heartbeat if my CPU was 20 times faster. Thank you, potential trolls.

My commandlines:

avs4x26x --x26x-binary x265_12 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao -o "Touhou Anime1.2 2pass.hevc"
avs4x26x --x26x-binary x265_12 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao -o "Touhou Anime1.2 2pass.hevc"
avs4x26x --x26x-binary x265_13 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.3 2pass.hevc"
avs4x26x --x26x-binary x265_13 "TouhouAnime.avs" --pass 2 --bitrate 66 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.3 2pass.hevc"
avs4x26x --x26x-binary x265_14 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.4 2pass.hevc"
avs4x26x --x26x-binary x265_14 "TouhouAnime.avs" --pass 2 --bitrate 66 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.4 2pass.hevc"
avs4x26x --x26x-binary x265_15 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.5 2pass.hevc"
avs4x26x --x26x-binary x265_15 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.5 2pass.hevc"
avs4x26x --x26x-binary x265_16 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.6 2pass.hevc"
avs4x26x --x26x-binary x265_16 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.6 2pass.hevc"
avs4x26x --x26x-binary x265_17 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.7 2pass.hevc"
avs4x26x --x26x-binary x265_17 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.7 2pass.hevc"
avs4x26x --x26x-binary x265_18 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.8 2pass.hevc"
avs4x26x --x26x-binary x265_18 "TouhouAnime.avs" --pass 2 --bitrate 66 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.8 2pass 66.hevc"
avs4x26x --x26x-binary x265_19 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.9 2pass.hevc"
avs4x26x --x26x-binary x265_19 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime1.9 2pass.hevc"
avs4x26x --x26x-binary x265_20 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.0 2pass.hevc"
avs4x26x --x26x-binary x265_20 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.0 2pass.hevc"
avs4x26x --x26x-binary x265_21 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.1 2pass.hevc"
avs4x26x --x26x-binary x265_21 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.1 2pass.hevc"
avs4x26x --x26x-binary x265_22 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.2 2pass.hevc"
avs4x26x --x26x-binary x265_22 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.2 2pass.hevc"
avs4x26x --x26x-binary x265_23 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.3 2pass.hevc"
avs4x26x --x26x-binary x265_23 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.3 2pass.hevc"
avs4x26x --x26x-binary x265_24 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.4 2pass.hevc"
avs4x26x --x26x-binary x265_24 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.4 2pass.hevc"
avs4x26x --x26x-binary x265_25 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.5 2pass.hevc"
avs4x26x --x26x-binary x265_25 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.5 2pass.hevc"
avs4x26x --x26x-binary x265_26 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.6 2pass.hevc"
avs4x26x --x26x-binary x265_26 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.6 2pass.hevc"
avs4x26x --x26x-binary x265_27 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.7 2pass.hevc"
avs4x26x --x26x-binary x265_27 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.7 2pass.hevc"
avs4x26x --x26x-binary x265_28 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.8 2pass.hevc"
avs4x26x --x26x-binary x265_28 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.8 2pass.hevc"
avs4x26x --x26x-binary x265_29 "TouhouAnime.avs" --pass 1 --bitrate 67 --tune ssim --ref 1 --rd 2 --ctu 64 --no-rect --no-amp --early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 1 --me dia --subme 2 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.9 2pass.hevc"
avs4x26x --x26x-binary x265_29 "TouhouAnime.avs" --pass 2 --bitrate 67 --tune ssim --ref 5 --rd 6 --ctu 64 --rect --amp --no-early-skip --b-intra --no-tskip-fast --tu-intra-depth 3 --tu-inter-depth 3 --tskip --max-merge 4 --me star --subme 4 --merange 57 --weightp --weightb --rc-lookahead 40 --b-adapt 2 --bframes 8 --cutree --sao --no-rskip --limit-modes --rd-refine --limit-refs 1 --min-cu-size 8 --rdoq-level 2 --lookahead-slices 1 --deblock=1:1 --no-fast-intra --psy-rdoq 0 -o "Touhou Anime2.9 2pass.hevc"

Source video: https://www.sendspace.com/file/f044m0

Avisynth script for the video:

ffvideosource("M:\Touhou clip.mkv")
spline64resize(720,480)
trim(8,5007)

FYI: If you're about to complain that I'm only testing on one type of content, I tested it on a photographic music video too. Quality is not improving on that one either.

[Hoser Rob]

,.... I had this discussion with Selur a year ago and he fell silent.....

Out of boredom?

[Aludin]

Oh what a funny guy!

[Bernix]

Hi,
just trolling, but my personal opinion is you have to measure more subjective than SSIM metrics. Probably it is for you new, but i think this example will explain lot. HEVC/x265 is very aggresive in terms of compression, probably therefore is x264 much faster and more effective when encoding lossless. Main purpose of this format/codec is deliver very high subjective quality at much lower bitrate than his predecesor. And he does it. So at some point is math metric useless. If it is opposite HEVC/x265 have to shine in lossless as well, but didnt. Slow and result is bigger than x264. So all psychovisual features that are used compared with original with any math metrics will show it is wrong, but judge by your eyes!


Edit: Also give a chance CRF it is faster than 2pass and quality is constant.



Bernix

[Aludin]

Hi, just trolling

Obviously.

Probably it is for you new

Wrong. Been a Blu-ray ripper since 2007.

I also uploaded the actual encoded videos for a reason. Would you LOOK at them and tell me with a straight face that the quality is better before randomly gibbering? I spent hours of my time setting that test up, you can spend a few minutes to read a little bit more than just 3 words of my post.

Edit: Also give a chance CRF it is faster than 2pass and quality is constant.

Don't care about speed, I care about the fact that that x265 1.0 outputs the same subjective quality as x265 2.9 and I want others to try and reproduce my findings, because if it's only me that's noticing this then I really wanna know what I'm doing wrong.

Hi, just trolling

You said it, buddy.

[Bernix]

Since your settings is still same for most than 10 years and you didnt notice advantage of CRF so it is weird. With CRF and given preset you will get results that can anybody reproduce and told you about what is right or wrong in your settings. Two pass encoding is obsolete thing, last longer and quality vary very. BTW why are you using it still (now meaning format HEVC)? Leave it alone in dark corner, when is it crap without future. Apparently not good enough for you. Mouning here, using 2pass not allowing codec do they best limited him, you will get nowhere.
Also you didnt explained lossless isue with your own words. And using math metrics here is therefore misleading. Because this format push hard to get best subjective quality.
Have a nice day "ripper"


Forgot to say, so why are you waving with encoding speed if it doesnt matter? LOL

[poisondeathray]

1) Speed difference is the big thing that sticks out. Something is wrong if you're seeing 5-6x difference.

Quick test using same 2nd pass settings as above, crf mode , v1.2 is faster - I'm getting ~1.35-1.45x speed compared to v2.8




2) "quality"

Can you say with absolute certainty something like SSIMPlus 99.02 is "better" than 99.01 ? Not really .

If say 6 or 7 metrics suggest the same conclusion , then it's a somewhat stronger statement

SSIMPlus has not been validated independently, nor tested extensively. It's potentially biased because the limited research conducted is based on the people selling the product.

Measurements like VMAF, PSNR, SSIM, MS_SSIM, PSNR-HVS-M, etc.. each have various pros/cons, strengths in some situations, weaknesses in others. Strong at predicting some types of content, overscore on others etc... but at least they are verified and independently testable

People are typically more interested in a minimum level of quality , especially at lower bitrates. If the "average" is say "x" , that's meaningless if a section of encode "A" is terrible , but average is the same as encode "B" . A single aggregate score doesn't convey that type of info

at 256 it's flawless.

Some banding/blocking issues, ugly fades .

Oversharpened, halos - but that's mostly from the Spline64 resize

[Aludin]

Since your settings is still same for most than 10 years

What?

and you didnt notice advantage of CRF so it is weird.

CRF with x265 1.2 is still better quality than CRF with latest x265. There was a very good reason I used 2pass, to control the (extremely tiny) bitrate otherwise this test would be useless. A test is not scientific until you remove all variables. The only variable is the x265 version and whatever new encoding settings it may have.
And I couldn't decipher any of the garbage you wrote after. I'll have the interpreter here in a week who works with children with birth defects.

@poisondeathray

Can you say with absolute certainty something like SSIMPlus 99.02 is "better" than 99.01 ? Not really .

...not what I was implying at all. If anything, that suggests it is the SAME quality. Wow, 0.001% better quality! Maybe next year it'll be 0.002%!

This thread is not about objective quality and I don't care to get into that pointless debate. It's about whether my observations about x265's quality stagnating despite the new encoding settings is true or not.

If not, what am I doing wrong?

Can you provide an encode of this source with better quality than mine? Just keep the bitrate, the --refs, bframes and lookahead the same.

Some banding/blocking issues, ugly fades .

On all of them? Proves my point don't you think?

[poisondeathray]

If anything, that suggests it is the SAME quality. Wow, 0.001% better quality! Maybe next year it'll be 0.002%!

I agree - it looks like nothing dramatically improved on this type of content at low bitrates . Maybe it's near the limits

I don't like the metric because it's an unknown quantity. The behaviour is not well established, it' s not used often. If you had provided a bunch of other metrics that said the same thing, then you could put more weight into suggesting "similar quality" or whatever .

But the quality has improved at typical bitrates on "normal" film type content, at least with typically used settings . Much less blurring, more detail retention . If you recall those were among the main complaints earlier on, and even x264 seemed to do better than x265. Not any more . So maybe that's what they were concentrating their efforts on

If not, what am I doing wrong?

Something is wrong with your reported speeds. Maybe a pipe issue or something. I used vapoursynth/vspipe, but ffmpeg pipe was about the same too

Because : 4-5x slower, with (the assumption of) of similar quality would not a good tradeoff . Hell, even slightly slower isn't a good tradeoff, it's backwards

Also, simpler settings (maybe "slower" preset with some minor changes) , quality is similar, but 3-4x faster (or about 10-12x what you reported)

I'd have to look at your settings more closely and what switches were changed and some of the differences

Some banding/blocking issues, ugly fades .

On all of them? Proves my point don't you think?

You said 256kb/s was "perfect". I'm just reporting that it's not "perfect" - there are the typical problems that plague x265 (and x264)

I don't think you uploaded it, but 10bit @256k , those issues become significantly improved, but still not quite perfect. At very low bitrates like 67kbps, 10bit is probably worse, because the encoder precision efficiency gains do not offset the cost of higher bits





Next is to test AV1 and XVC . AV1 tends to blur a lot, like x265 earlier on , but I suspect it will do well on this type of content . XVC is supposed to be the best right now in terms of semi-usable codecs

[Bernix]

Will not laught that you need birth defect interpreter it is sad.
With 2 pass test you will achieve nothing. Arising bitrate in this case, supposing distribution of bitrate will be same.
Spline resize was mentioned, you also mess with ratio of w and h. But probably you correct it in right way. It is simply different than your original, so hardly to compare. But it is almost 20% difference in AR (mentioned it because you compare with what?). Also original AVC has 9 ref frames. You told you dont wish to be mentioned. But in anime and animation, it is one of most powerful feature. Raised bframes to 8... And that speed drop is more than significant, something can be totaly wrong and affecting result.
You simply have settings not to get best that you can. Especialy in low bitrate you need everything that can save some bits. Mentioned blurry, probably psychovisual on can help even bitrate is low but resolution is also low. I dont like anime and also VFR, but this is clear case it can save bits a lot (iam aware that codec should take care about it itself but very good oportunity test VFR). Actual framerate is something like 8fps (it means it has almost 0bits, but your setting of type and number of i, b or p frames is affected then) when camera is not moving.
Also not sure your me and subme settings, but think ME+1 (star) and subme+1 as well will improve quality. Of course encoding will last longer, but i think you are aiming for quality.
Have a nice day.
And dont worry, you cant make me angry. All are looking for problems in software everywhere, and most problems is at the end on side of user.

[Aludin]

I agree - it looks like nothing dramatically improved on this type of content at low bitrates . Maybe it's near the limits

Dramatically improved? It's not improved at all. I tested on 3 different bitrates. How can you call 256 low? Anything higher and even x264 will look the same.

I don't like the metric because it's an unknown quantity.

Then stop bringing it up. I posted the actual videos for a reason. The metric is a guide.

But the quality has improved at typical bitrates on "normal" film type content, at least with typically used settings.

Not in my experience.

Because : 4-5x slower, with (the assumption of) of similar quality would not a good tradeoff . Hell, even slightly slower isn't a good tradeoff, it's backwards

Assumption? We're getting nowhere if posting the evidence was pointless.

You said 256kb/s was "perfect". I'm just reporting that it's not "perfect" - there are the typical problems that plague x265 (and x264)

Original post edited to clear up the confusion.

Next is to test AV1 and XVC . AV1 tends to blur a lot, like x265 earlier on , but I suspect it will do well on this type of content . XVC is supposed to be the best right now in terms of semi-usable codecs

Slow down there, we are still yet to reproduce my findings on x265. I welcome your encode of the source I posted.

@Bernix, stop posting off-topic shit to my thread, at least until we get a hold of the interpreter. He was the world's first candidate to successfully translate Trigglypuff's inane retardation into legible English so your text shouldn't be too challenging.

[poisondeathray]

I agree - it looks like nothing dramatically improved on this type of content at low bitrates . Maybe it's near the limits

Dramatically improved? It's not improved at all. I tested on 3 different bitrates. How can you call 256 low? Anything higher and even x264 will look the same.

That's what "nothing" means. Nothing dramatically improved . We're saying the same thing

Are you calling 67kbps not low ?

256 for 8bit wasn't enough to make it "decent" everywhere - so I'm certainly not calling it high. There are missing objects like birds. I know a metric won't tell you that, but your eyes will

But the quality has improved at typical bitrates on "normal" film type content, at least with typically used settings.

Not in my experience.

Maybe you should revisit it later. The typical blurring of old is gone. Fine detail and grain retained now with proper settings. Much much better, it can replace x264 for that scenario now, whereas before, x264 was actually better in many cases

Because : 4-5x slower, with (the assumption of) of similar quality would not a good tradeoff . Hell, even slightly slower isn't a good tradeoff, it's backwards

Assumption? We're getting nowhere if posting the evidence was pointless.

But is it that much of a revelation that quality is similar? For example, 3 references means the same as 3 references . hex is hex and so forth . If you use the same settings, and nothing else is changed, why wouldn't you expect similar results ? So what are the changes ?

For example, in general use cases, there was a huge difference between x264 pre AQ , and after AQ was added especially on live action content at typical bitrates. That was a major change that you could actually see . If you used the same settings (no AQ) you get... no surprise - similar results

Maybe the changes are in speed. I know some defaults were tweaked, some instructions added . For example, they didn't have AVX512 back then. Maybe your settings are limiting something. If the speed is actually faster (on some systems), maybe you can now use slower settings to get the same speed , yet higher compression efficiency . Maybe you can add more ref, b etc... Maybe a more illuminating test would be set a min FPS, and use whatever settings you want. I haven't used x265 as much as x264, not as familiar with the behaviour or what was changed a few years ago