small artifact in latest commit

[shinchiro]

I'm comparing commit 99d3bf2c0c8d with 975352b2c022, I see there's quality changes from both commits. Around ~15 frame after keyframe (scenechange), small part of a frame show artifact which is not preset in 99d3bf2c0c8d. Only occur when encoding in low bitrate (--bitrate 500)

Feel free to close this issue if its not bug

[Deepthi Nandakumar]

Can you provide a commandline with link to video (dont bother if it's a freely available one)?

[shinchiro]

cli:

--bitrate 500 --preset medium --tu-intra-depth 2 --tu-inter-depth 2 --rd 6 --psy-rd 0.5 --max-merge 5 --me umh --subme 4 --no-strong-intra-smoothing --rdpenalty 1 --rc-lookahead 90 --bframes 8 --aq-mode 2 --no-sao --deblock -3:-3

screenshot: http://screenshotcomparison.com/comparison/144004 (very small artifact in hair)

clip: https://d.maxfile.ro/dbjufiyyiw.mkv (at frame 106)

[Deepthi Nandakumar]

Yes, I confirm there is a small loss of detail in the hair in your screenshot comparison.

69d55d4c53eb likely changed the slicetype for the frame you refer to. There are 2 more patches in the same series that have not been pushed yet - we can test your commandline to see if the quality does not recover.

[shinchiro]

Since 1.8 already released I re-run this test again with latest tip & with same cli. The result is still same but I somehow able to trace that setting --rd 5 or 6 will introduce this artifact problem. --rd 4 and below does not produce this problem.

Aside from that, I can see some frames showed quality improvement :)

[shinchiro]

Just testing the same clip with latest commit. Seem this bug no longer exist in e8f9a60

feel free to close this

[Deepthi Nandakumar]

Thanks for your help with the quality testing. We're looking to aggressively improve subjective quality - so all testcases and bugs welcome.