Doom9's Forum - View Single Post - x265's CRF versus low contrast HDR sources..

Boulder · 12th November 2018, 19:21

What does the "auto variance" actually mean? I've always thought that aq-mode 1 is already some kind of automatically varying mode based on qg-size.

On HDR sources, mode 2 seems to produce noticably smaller files for the same CRF than mode 1. This would somehow point to the problem with the flat, non-tonemapped image x265 seems to use while analyzing things. Using aq-strength 1.8 for mode 1 makes the bitrate shoot through the roof compared to strength 1.0. I'm going to do some visual compares as soon as I have the time, but it's difficult because a 2-pass encode is a no-no since I'm not hitting a specific size. Comparing those two strengths at the bitrate that strength 1.0 produces at CRF 15 or so is not fair because strength 1.8 would require so much more bits.

12th November 2018, 19:21	#39 \| Link
Boulder Pig on the wing Join Date: Mar 2002 Location: Finland Posts: 5,733	What does the "auto variance" actually mean? I've always thought that aq-mode 1 is already some kind of automatically varying mode based on qg-size. On HDR sources, mode 2 seems to produce noticably smaller files for the same CRF than mode 1. This would somehow point to the problem with the flat, non-tonemapped image x265 seems to use while analyzing things. Using aq-strength 1.8 for mode 1 makes the bitrate shoot through the roof compared to strength 1.0. I'm going to do some visual compares as soon as I have the time, but it's difficult because a 2-pass encode is a no-no since I'm not hitting a specific size. Comparing those two strengths at the bitrate that strength 1.0 produces at CRF 15 or so is not fair because strength 1.8 would require so much more bits. __________________ And if the band you're in starts playing different tunes I'll see you on the dark side of the Moon...