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Old 16th October 2018, 17:52   #6437  |  Link
benwaggoner
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Join Date: Jan 2006
Location: Portland, OR
Posts: 4,750
Quote:
Originally Posted by Boulder View Post
My sources are just regular movies or TV series. I'll tune CRF as the last item once I've got all the rest in place.

--merange 44, basically lowering it from the default 57 which I understand is meant for 4K. For 720p, I've used 38 all the time. I think this is remains of littlepox's set of "tune film" parameters.
It's not THAT frame size dependent, but 44 is probably fine.
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--splitrd-skip, in my old notes, I didn't find it cause any ill effects. Do you have any specific information why it's a "bad idea"?
No reason it would be a bad idea; I just haven't seen it used before. Generally parameters that have a reliable quality/speed tradeoff are in a preset. But it isn't listed as experimental...

Anyone from MultiCoreWare care to weigh in? What's the tradeoff? Is this something that should get added to the faster presets, or default to On but off in --preset placebo?
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--max-merge 2, values 3-4 tested and it caused blur. One of the things in x265 that is different from x264 - the slower presets don't mean similar quality at lower final bitrate
Yeah, with the many more tools available in HEVC, the differences between presets are greater. Odd that it causes blur; this should be a speed/quality tradeoff. You should file an issue here with repro details: https://bitbucket.org/multicoreware/...ew&status=open
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--deblock -2:-2, no need for intense deblocking according to my tests
Well, to improve compression efficiency. Did you see any issues with using 0:0?
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--rdpenalty 1, trying to favour smaller blocks.
Have you seen any experimental validation of it helping in x265 2.4+? I found places where it was helpful in older versions, but not recently.
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--qg-size 16, tested values from 64 to 8, 16 looked best (in terms of distortion in small details again) when compared frame-by-frame. Tested with a 720p encode, so I'll need to check that also with 1080p later.
I would expect it would look better, but at some cost to efficiency due to the signaling overhead. --opt-cu-delta-qp might help that some. What sorts of bitrates are you targeting/getting?
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--bframes 10, some video utilizes a lot of B-frames for some reason. Not a big slowdown so I've kept it at that all the time.
Why 10 specifically? I'd use either 8 (most tested, as it's in the slower+ presets) or 16 (maximum allowed).
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