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Old 22nd October 2018, 04:07   #6461  |  Link
Boulder
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I ran the encodes again to produce the logs, if you want to have a look: https://drive.google.com/open?id=1Ej...nsPbY8qyl6tFMA . The flat part scene I mentioned appears several times, for example frames 0-117 contain that one.
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Old 27th October 2018, 12:30   #6462  |  Link
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This is probably a silly question, but here goes anyway: if I use --hdr-opt, do I need to feed the encoder with 10-bit data or is 16-bit data as good if the source is a standard UHD with HDR? I always process things in 16-bit domain and let the encoder dither down to 10 bits.
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Old 27th October 2018, 14:52   #6463  |  Link
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Is there a release note for v2.9?
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Old 27th October 2018, 22:01   #6464  |  Link
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I never saw any...
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Old 27th October 2018, 22:44   #6465  |  Link
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Originally Posted by iwod View Post
Is there a release note for v2.9?
https://bitbucket.org/multicoreware/...e-view-default
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Old 28th October 2018, 01:35   #6466  |  Link
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This is probably a silly question, but here goes anyway: if I use --hdr-opt, do I need to feed the encoder with 10-bit data or is 16-bit data as good if the source is a standard UHD with HDR? I always process things in 16-bit domain and let the encoder dither down to 10 bits.
The actual x265 encoder instance is going to start encoding with 10-bit 4:2:0 pixels one way or another. It gets converted somewhere upstream, perhaps even in the x265 exe. But that’s a filter that runs before the actual codec itself.

If you’re changing bit depth in x265, remember to always use —dither.
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Old 28th October 2018, 08:02   #6467  |  Link
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It is kind of weird that the v2.9 release notes is only available in the stable version, but not default or even latest.
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Old 28th October 2018, 09:25   #6468  |  Link
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It seems that even zeranoe ffmpeg stays at x265 2.8 for a long time.

By the way, I'm not a fan of hard-coded dithering. Dithering should be handled as part of creative editing before the encoding process or left to the rendering after the decoding process.
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Old 29th October 2018, 11:11   #6469  |  Link
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Quote:
Originally Posted by Boulder View Post
This is probably a silly question, but here goes anyway: if I use --hdr-opt, do I need to feed the encoder with 10-bit data or is 16-bit data as good if the source is a standard UHD with HDR? I always process things in 16-bit domain and let the encoder dither down to 10 bits.
I would let x265.exe do the dithering, 'cause other dithering options like the Floyd Steinberg error diffusion may have a nicer look, but they could increase the bitrate required by x265. The built in dithering filter in x265 is supposed to dither everything down to the target bit depth without introducing banding. Blocks and macro blocks dithered by x265 are more likely to be recognised during the motocompensation by x265 than the ones dithered using a third party dithering method, therefore compression should be better.

In a nutshell, let x265 do the dithering and always pipe to it the highest bit depth you have, unless you like a specific dithering method and you have enough bitrate.
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Old 29th October 2018, 18:31   #6470  |  Link
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I would let x265.exe do the dithering, 'cause other dithering options like the Floyd Steinberg error diffusion may have a nicer look, but they could increase the bitrate required by x265. The built in dithering filter in x265 is supposed to dither everything down to the target bit depth without introducing banding. Blocks and macro blocks dithered by x265 are more likely to be recognised during the motocompensation by x265 than the ones dithered using a third party dithering method, therefore compression should be better.

In a nutshell, let x265 do the dithering and always pipe to it the highest bit depth you have, unless you like a specific dithering method and you have enough bitrate.
Note there are two dithering modes in x265. The basic one if you don’t specify anything, and the more advanced one if you use —dither.
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Old 31st October 2018, 00:08   #6471  |  Link
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Say, does anyone have any data showing potential benefits of using some of the "beyond placebo" settings?

For example
  1. --subme 6 or 7 instead of 5
  2. --me sea instead of star
  3. --bframes 16 instead of 8
  4. --ref 6+ instead of 5
  5. --tskip
  6. --cu-lossless

I've fond some value in very low bitrates or unusual content from all but the higher subme and me, which I've not tried.
--me sea in particular cuts speed enormously.

Tskip and cu-lossless can help with anime, small text, screen captures, and other stuff with sharp detailed edges.
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Old 31st October 2018, 11:29   #6472  |  Link
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Originally Posted by benwaggoner View Post
Say, does anyone have any data showing potential benefits of using some of the "beyond placebo" settings?

For example
  1. --subme 6 or 7 instead of 5
  2. --me sea instead of star
  3. --bframes 16 instead of 8
  4. --ref 6+ instead of 5
  5. --tskip
  6. --cu-lossless

I've fond some value in very low bitrates or unusual content from all but the higher subme and me, which I've not tried.
--me sea in particular cuts speed enormously.

Tskip and cu-lossless can help with anime, small text, screen captures, and other stuff with sharp detailed edges.
Is --subme tied to RDO in the way that it is in x264?

In x264, --subme 6 upwards have increased levels of RDO. But seems that RDO is its own separate thing in x265 with RD levels 1-6 and rd-refine being a separate switch too.
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Old 31st October 2018, 17:08   #6473  |  Link
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Originally Posted by RainyDog View Post
Is --subme tied to RDO in the way that it is in x264?

In x264, --subme 6 upwards have increased levels of RDO. But seems that RDO is its own separate thing in x265 with RD levels 1-6 and rd-refine being a separate switch too.
Yeah, subme does have some impact on rate control, but --rd is where the action is at.

From x265.readthedocs.io

Quote:
Amount of subpel refinement to perform. The higher the number the more subpel iterations and steps are performed. Default 2

At –subme values larger than 2, chroma residual cost is included in all subpel refinement steps and chroma residual is included in all motion estimation decisions (selecting the best reference picture in each list, and chosing between merge, uni-directional motion and bi-directional motion). The ‘slow’ preset is the first preset to enable the use of chroma residual.
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Old 31st October 2018, 20:39   #6474  |  Link
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Originally Posted by benwaggoner View Post
Say, does anyone have any data showing potential benefits of using some of the "beyond placebo" settings?

For example
  1. --subme 6 or 7 instead of 5
  2. --me sea instead of star
  3. --bframes 16 instead of 8
  4. --ref 6+ instead of 5
  5. --tskip
  6. --cu-lossless

I've fond some value in very low bitrates or unusual content from all but the higher subme and me, which I've not tried.
--me sea in particular cuts speed enormously.

Tskip and cu-lossless can help with anime, small text, screen captures, and other stuff with sharp detailed edges.
When I was tuning x265's presets, I tried all of these options that go beyond placebo, to see what should be included in placebo. You and anyone else are welcome to try them again, but I found it was easy to massively increase encode times, but impossible to get any meaningful improvement in efficiency.
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Old 31st October 2018, 23:28   #6475  |  Link
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What idiom would you give a configuration "beyond placebo"? Possibly "insane", like LAME MP3...
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Old 1st November 2018, 02:02   #6476  |  Link
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What idiom would you give a configuration "beyond placebo"? Possibly "insane", like LAME MP3...
ultra placebo. Or very placebo since that would match with very slow.
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Old 1st November 2018, 05:10   #6477  |  Link
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When I was tuning x265's presets, I tried all of these options that go beyond placebo, to see what should be included in placebo. You and anyone else are welcome to try them again, but I found it was easy to massively increase encode times, but impossible to get any meaningful improvement in efficiency.
Indeed. “—me full —cu-lossless” will tank speed unbelievably without even trivial quality improvements for typical content and use cases.

I have seen visible and measurable value from ref 6, bframes 16, and tskip at <150 Kbps. Of course, using a lot of MIPS/pixel isn’t nearly so painful at low frame sizes and bitrates.
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Old 1st November 2018, 10:27   #6478  |  Link
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Yeah, subme does have some impact on rate control, but --rd is where the action is at.

From x265.readthedocs.io
Well yeah, that's why I asked. As --subme in the x265 docs doesn't specifically mention RDO.

But in x264 it's :-

Quote:
subme

Default: 6

Set the subpixel estimation complexity. Higher numbers are better. Levels 1-5 simply control the subpixel refinement strength. Level 6 enables RDO for mode decision, and level 8 enables RDO for motion vectors and intra prediction modes. RDO levels are significantly slower than the previous levels.

QPel SAD 1 iteration
QPel SATD 2 iterations
HPel on MB then QPel
Always QPel
Multi QPel + bime
RD on I/P frames
RD on all frames
RD refinement on I/P frames
RD refinement on all frames
QP-RD (requires --trellis=2, --aq-mode > 0)

So it seems to me that --subme in x265 is as per --subme 1-5 in x264.

And the RD stuff of x264 --subme 6-11 is branched off into it's own thing in x265 with selectable RDO levels, rd-refine as a separate option etc.
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Old 2nd November 2018, 12:59   #6479  |  Link
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x265 2.9+4-471726d3a046

fixes: rowStat computation in const-vbv; memory reset size in dynamic-refine; linking issue on non x86 platform
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Old 4th November 2018, 19:33   #6480  |  Link
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Say, does anyone have any data showing potential benefits of using some of the "beyond placebo" settings?

For example[LIST=1][*]--subme 6 or 7 instead of 5
I don't know what data you're looking for besides "yes, it looks better." I wrote the following some months back in this thread:

1) imo, if you care about things that move, (and picture quality in general), you have to use sub-motion pixel subme 7. 5 is good, and is as low as I ever set that even on files I'm trying to finish fast, but 5 is easily visually inferior to 7 imo. 7 of course takes longer to encode though.

I'm usually around CRF 22-23 (with nearly all quality settings turned on). It probably has lesser effect at CRF 18.

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