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Old 11th April 2018, 13:05   #621  |  Link
Shevach
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AV1 supports 1/8-pel motion precision (optional, specified by frame header parameter - allow_high_precision_mv). i wonder what's a gain in coding efficiency to exploit high MV precision? In HEVC and AVC the precision is 1/4-pel (for luma). In case of high-frequency video (HFR) or even for 60 fps 1/8-pel probably is redundant. Perhaps, 1/8-pel MV precision is beneficial for 4K resolution with 30 fps rate?
Unlike to HEVC development (where all was public and all discussions/contributions were located at jct-vc repository), some AV1's decisions are non-graspable to me. Who knows - under what circumstances 1/8-pel motion vector precision is beneficial vs. 1/4 pel one?
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Old 11th April 2018, 13:12   #622  |  Link
Shevach
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Maybe for low-resolutions and low frequency sub-pixel movements achieve the 1/8 granularity?
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Old 11th April 2018, 23:43   #623  |  Link
ianken
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With a current FFMPEG build I get 0.2 fps on 1080p content. And that's a single stream.

To use this for next-day TV VOD it needs to be...faster. Or, maybe the ffmpeg integration is not fully baked? The CPU certainly is not loaded in any appreciable way. It's not even clocking up.
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Old 12th April 2018, 00:31   #624  |  Link
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The bitstream is not frozen, so you should use av1 only for testing... but currently it's too slow even for that. Once it is frozen, i expect the speed optimizations will come fairly quickly. Their stated goal is around a hundred times faster encoding speed at the end of the year. Hopefully with not significant quality drop.
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Old 12th April 2018, 01:12   #625  |  Link
vidschlub
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Quote:
Originally Posted by colinhunt View Post
Could you tell me where I can find this filter on x265? I went through its documentation and found nothing applicable.
You might need to set a +film flag or disable 'nograin' I honestly can't recall, I'm really a newbie at best, others here can help.

I've done a lot of side by side comparisons and if you don't have the side by side, you can trick yourself into thinking it's better, but a lot of detail is lost and washed out.

Someone here will know for sure.
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Old 12th April 2018, 03:45   #626  |  Link
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Quote:
Originally Posted by Shevach View Post
AV1 supports 1/8-pel motion precision (optional, specified by frame header parameter - allow_high_precision_mv). i wonder what's a gain in coding efficiency to exploit high MV precision? In HEVC and AVC the precision is 1/4-pel (for luma). In case of high-frequency video (HFR) or even for 60 fps 1/8-pel probably is redundant. Perhaps, 1/8-pel MV precision is beneficial for 4K resolution with 30 fps rate?
Unlike to HEVC development (where all was public and all discussions/contributions were located at jct-vc repository), some AV1's decisions are non-graspable to me. Who knows - under what circumstances 1/8-pel motion vector precision is beneficial vs. 1/4 pel one?
Doesn't seem to have ever been discussed in public. I bet it was a test an engineer inserted and it was just never removed; I wonder if it's ever been used in real life.
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Old 12th April 2018, 06:25   #627  |  Link
nevcairiel
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VP9 already had 1/8 pel MV precision, it was probably just inherited from there.
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Old 12th April 2018, 21:23   #628  |  Link
colinhunt
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Harmonic showed a comparison demo at NAB, pitting AV1, AVC, HEVC and JVET against each other. At the equivalent bitrate of 1.9 Mbps they got the following results:

Codec -- PSNR -- VMAF

AVC -- 32.7 -- 58
HEVC -- 36.7 -- 80
AV1 -- 37.2 -- 83
JVET -- 38.5 -- 88

That's all the info I got.
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Old 12th April 2018, 22:52   #629  |  Link
LigH
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They still use PSNR? Don't we prefer SSIM/dB today? Well, VMAF is more like that.

What does it prove? ... More computational complexity is the solution? We need more supercomputers.

This statement might contain sarcasm.
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Old 14th April 2018, 12:39   #630  |  Link
iwod
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Quote:
Originally Posted by colinhunt View Post
Harmonic showed a comparison demo at NAB, pitting AV1, AVC, HEVC and JVET against each other. At the equivalent bitrate of 1.9 Mbps they got the following results:

Codec -- PSNR -- VMAF

AVC -- 32.7 -- 58
HEVC -- 36.7 -- 80
AV1 -- 37.2 -- 83
JVET -- 38.5 -- 88

That's all the info I got.
VMAF 80 vs 83......

Um.....
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Old 14th April 2018, 13:14   #631  |  Link
LigH
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For this one selected sample, maybe? Many show demos pick the one comparison with the results making the own preferred product look best. I do not even see any link to this show here (maybe colinhunt was there in person?).
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Old 15th April 2018, 19:35   #632  |  Link
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^ No, I wasn't, just happened to bump into a short video of the demo (and the scores) on Twitter.
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Old 16th April 2018, 08:48   #633  |  Link
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AV1 vs x265 / libvpx-vp9 / x264 / QSV(H.264,LA-ICQ)

Clip: Animation, 1920x1080, 335frames(13.972sec)
Metric: VMAF, SSIM


Last edited by enctac; 16th April 2018 at 12:05. Reason: upload image to imgur
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Old 16th April 2018, 10:46   #634  |  Link
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Originally Posted by enctac View Post
AV1 vs x265 / libvpx-vp9 / x264 / QSV(H.264,LA-ICQ)

Clip: Animation, 1920x1080, 335frames(13.972sec)
Metric: VMAF, SSIM

Attachment 16311
The attachment will never get approved, you need to upload it somewhere else.
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Old 16th April 2018, 12:13   #635  |  Link
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That is x265 doing surprisingly well.
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Old 16th April 2018, 17:14   #636  |  Link
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enctac for Vp9 in comparisons I recomend to disable frame-parallel as is at outdated feature and use row-mt because in my tests it don't hurt quality and inprove speed (in reality row-mt has highther metrics but the variation is so low that statistically is insignicant, it has a variance of 0.0002 for ssim scores and 0.04 for vmaf scores). Plus apart of CPU 0 is also interesting to use CPU 1 an least one time in the comparison.
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Old 16th April 2018, 23:29   #637  |  Link
dissory
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Can anyone please explain this for dummies?

How good is AV1 in comparison to HEVC in terms of quality and size right now (and will these get better over time or are they pretty much done with most major improvements)?
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Old 16th April 2018, 23:35   #638  |  Link
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As usual, it is impossible to give a guaranteed ratio of efficiency between two codecs, it always depends on the material processed with it, as well as how annoying a specific person rates the loss.

The development of both HEVC (x265) and AV1 is not yet done, and AV1 is in a much earlier stage (it has not even many speed-up techniques implemented yet). But it is already considerably more efficient than x265. Unfortunately, it also requires a lot more time to encode.
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Old 16th April 2018, 23:39   #639  |  Link
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But it is already considerably more efficient than x265.
Any rough estimate % on how much more efficient on average?
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Old 17th April 2018, 09:05   #640  |  Link
LigH
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At its current speed, I don't have the patience to run elaborate test sequences, they would probably take months without using a "render park".

And how much difference does it mean to you whether it is 10% or 15% or 20%? Where is your personal threshold for ... which action?
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