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Old 16th October 2022, 22:02   #21  |  Link
benwaggoner
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What is the difference between tskip and tskip-fast? Why they can be used together? What will happen?
--tskip-fast doesn't do anything if --tskip isn't on. If --tskip is on, it will do a slower, more thorough job without --tskip-fast than if it is on. For most content, --tskip is only occassionally helpful, and --tskip-fast catches most of those cases. --tskip by itself has a pretty big perf hit, So I recommend trying it with --tskip-fast first, and seeing if there is any benefit. If there is benefit, try without --tskip fast and see if there is additional benefit worth the slower encoding speed.
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Old 16th October 2022, 22:03   #22  |  Link
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In retrospect, it should have been implemented as --tskip 0, 1, or 2, following the other speed/quality ordinal parameters like --me, --subme, --limit-refs, etc.
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Old 16th October 2022, 22:12   #23  |  Link
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I've made a very quick test on a 10 frames video, speed difference between with and without tskip is 0,52fps to 0,49fps, i can live with that...
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Old 18th October 2022, 19:46   #24  |  Link
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I've made a very quick test on a 10 frames video, speed difference between with and without tskip is 0,52fps to 0,49fps, i can live with that...
I suspect the gap will be larger with a more representative number of frames. You need to encode a decent multiple of --keyint to get accurate performance numbers. 10 frames is less than default --rc-lookahead, and fps is typically way higher for the --rc-lookahead duration.

--rc-lookahead is really a secret weapon for improving quality and reducing quality fluctuations with single-pass encoding.
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Old 19th October 2022, 18:52   #25  |  Link
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Seeing the speed of a big real encode i've started, I think my true drop is 0,50 average to 0,42 average. It's allmost 20%... I'll check with --tskip-fast... If it catches allmost all the cases for a speed drop less significant, it will be enough for me. rc-lookahead is set to 48.
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Old 21st October 2022, 11:16   #26  |  Link
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Yeah, tskip is too impactful on performance with my current step, not the end of the world for me, I'm pretty happy with my current detail settings. I would use rect, amp, hme and tskip if I could, But a full movie is 2 days with my settings, and 20+ days with just adding these 4 settings, so that shows you how much impact they have, and how unoptimized my pc is for encoding, LOL.

Because SolLevante is only around 4 thousand frames, I encoded that using the highest settings possible, placebo and hme / tskip and the quality is shockingly good. Took me 2 days, but I wanted to see it and it doesn't disappoint.

Unless there's anymore settings that Ben is keeping secret from us, I think its about as good as it gets. haha...

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Old 22nd October 2022, 00:35   #27  |  Link
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Wow, those four commands should NOT cause encoding time to go up 10x! I haven't seen --hme really prove its value yet. Have you?

You can get --amp and --rect with much less of a hit using --limit-refs 2 or 3
And of course, add --tskip-fast with tskip
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Old 23rd October 2022, 19:22   #28  |  Link
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What do you know (brief/quick) of the new commited option ?
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Old 24th October 2022, 02:15   #29  |  Link
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What do you know (brief/quick) of the new commited option ?
A MCTF filter essentially removes psychovisually irrelevant detail, making the video easier to encode. So better quality at a fixed bitrate, lower bitrate for a fixed quality. It can be quite helpful for moderate-low bitrates.

I've not tried this new implementation yet myself.
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Old 24th October 2022, 16:35   #30  |  Link
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@benwagonner
Sorry to bother you again...
First, thank for explanation, i read the code of the commit, and from the few i understood, it adjusts, for each frame, according the content, the aq-mode. It seems indeed interesting.
Also, if i understood properly, you just need to put --sbrc, no aq-mode is needed anymore.

--hevc-aq and aq-mode are exclusive. Do you happend to know (by any chance), if there is one "better" than the other ? Or is it just 2 differents ways, but with no one realy better than anoter ?

Don't tested yet --hevc-aq with sbrc, but from the few i understood, they should be also exclusive but see nothing about it in the commited code...
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Old 24th October 2022, 21:23   #31  |  Link
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@benwagonner
Sorry to bother you again...
First, thank for explanation, i read the code of the commit, and from the few i understood, it adjusts, for each frame, according the content, the aq-mode. It seems indeed interesting.
Also, if i understood properly, you just need to put --sbrc, no aq-mode is needed anymore.
That would be welcome! Different modes are appropriate for different kinds of content. And appropriate --aq-strength varies a lot too.

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--hevc-aq and aq-mode are exclusive. Do you happend to know (by any chance), if there is one "better" than the other ? Or is it just 2 differents ways, but with no one realy better than anoter ?
IIRC --aq-mode 4 is the final implementation of --hevc-aq.
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Old 25th October 2022, 17:13   #32  |  Link
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IIRC --aq-mode 4 is the final implementation of --hevc-aq.

Ah... Ok...
The, the choice would be between sbrc or aq-mode 5, which are both adaptative AQ modes.
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Old 25th October 2022, 21:46   #33  |  Link
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Ah... Ok...
The, the choice would be between sbrc or aq-mode 5, which are both adaptative AQ modes.
...assuming there is a build which has both --aq-mode 5 and sbrc. And that they mean the same things. That's the tricky thing with forks. I hope we can reunify everything useful back into mainline.
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Old 26th October 2022, 13:43   #34  |  Link
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Now there is...
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Old 26th October 2022, 20:10   #35  |  Link
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Now there is...
You mean this?
https://github.com/jpsdr/x265
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Old 26th October 2022, 21:57   #36  |  Link
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Yes it is.
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Old 27th October 2022, 19:39   #37  |  Link
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...assuming there is a build which has both --aq-mode 5 and sbrc.
You tried to play with 5? I am curious to read your findings about modes above 3.
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Old 28th October 2022, 20:15   #38  |  Link
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You tried to play with 5? I am curious to read your findings about modes above 3.
I've found --aq-mode 4 to be a good default for SDR content at this point, at least in the context of all the other tuning I do, and with mezzaine quality sources.

--aq-mode 2 does better for hdr still, at least in my target scenarios.
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Old 30th October 2022, 10:45   #39  |  Link
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I've found --aq-mode 4 to be a good default for SDR content at this point
What about 5?
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Old 31st October 2022, 03:44   #40  |  Link
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What about 5?
That's only in custom forks that I've not played with.
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