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Old 9th October 2019, 13:56   #1861  |  Link
dapperdan
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I couldn't find any x264 tune ssim encodes, but I did find some x265 tune PSNR that show basically the same pattern. Tuning for PSNR at the expense of Fast SSIM, while other metrics don't really change.

The major difference is that the PSNR tuning seems to help with CB and Cr for x265, not just the Y channel.

Fascinating. So it appears x264 and x265 have their own version of VMAF which is just the combination of PSNR and FastSSIM metrics.
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Old 9th October 2019, 15:03   #1862  |  Link
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So it appears x264 and x265 have their own version of VMAF which is just the combination of PSNR and FastSSIM metrics.
That sounds confusing to me. PSNR and SSIM are mainly frame-to-frame metrics, whereas VFAM should also consider motion, thus have a temporal window.

The main metric used in x264 and x265 is the "rate factor", if I'm not completely wrong...
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Old 9th October 2019, 15:36   #1863  |  Link
dapperdan
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I just meant in the sense that VMAF is a fusion of other metrics, including PSNR.

VMAF use fancy statistics to combine them all based how they agreed with subjective measurements but it looks like x264 just combined Fast SSIM and PSNR when they didn't move in opposite directions.
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Old 9th October 2019, 16:27   #1864  |  Link
mzso
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Will SVT-AV1 and rav1e be added to ffmpeg as encoder libraries?
Or is that not possible because of licensing?
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Old 9th October 2019, 18:55   #1865  |  Link
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AFAIK there are no licensing issues. Both rav1e and SVT-AV1 have open licences (BSD 2-Clause and BSD+patent). Some patches already seem to exist but it seems aren't fully ready yet (i.e. developers still need to do some work or want to wait a bit more for the respective projects to mature).
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Old 9th October 2019, 19:12   #1866  |  Link
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rav1e is still missing a stable C API for ffmpeg, IIRC.
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Old 10th October 2019, 01:51   #1867  |  Link
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Will SVT-AV1 and rav1e be added to ffmpeg as encoder libraries?
Or is that not possible because of licensing?
For rav1e we are waiting on releasing 0.1. We're down to one blocker bug, so it should be out soon: https://github.com/xiph/rav1e/issues/1636
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Old 10th October 2019, 01:54   #1868  |  Link
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Fascinating. So it appears x264 and x265 have their own version of VMAF which is just the combination of PSNR and FastSSIM metrics.
Unfortunately it's impossible to use VMAF directly for RDO because an encoder has to evaluate distortion on very small blocks, down to 8x8 pixels. So the best you can do is come up with something that approximates it.
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Old 10th October 2019, 07:43   #1869  |  Link
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Just that you mention rav1e ... this week they broke compilation for the x86 target, possibly in an attempt to add assembler optimizations. The developers seem to lack of a cross-compilation environment for x86 (where I am not sure if that specifically means 32 bit code) for automated testing. I discovered that issue during my usual sporadic runs of the media-autobuild suite.
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Old 12th October 2019, 13:49   #1870  |  Link
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dav1d 0.5.0 'Asiatic Cheetah'

The fast and small AV1 decoder, codename 'Asiatic Cheetah'. It supports all the AV1 features and all bitdepths.

0.5.0 brings large improvements in speed on SSSE3 CPU (up to 40% speedup), new speed improvements on AVX-2 (for 4-7%) and ARM64 (up to 10%) and ARM32. It introduces some VSX, SSE2 and SSE4 optimizations.
0.5.0 fixes some minor issues, can export ITU T.35 metadata and improves the player example.
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Old 14th October 2019, 07:42   #1871  |  Link
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Hi guys. I’m not good at English, sorry for that. Got file [Xrip][Nekopara][OVA_Extra][GB][1080P][AV1_10bit].mp4 from nyaa. Last and several dozen previous build of mpv playback it choppy. x86 and x64 version of mpv.
But mpc-hc 1.8.4.x86 playback it smooth. Only x86 build of mpc-hc 1.8.4, x64 also playback it choppy. And next builds of mpc-hc also playback it choppy. As far as I understand there were some changes in LAV Filters which led to the worst result. Maybe this information will be useful to someone.
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Old 14th October 2019, 10:18   #1872  |  Link
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MPC-HC 1.8.4 (LAV v0.73.1) uses libaom for AV1 decoding, 1.8.5 (LAV v0.74) uses dav1d. dav1d isn't optimized for 10 bit AV1 yet and it seems for this particular case and your hardware that libaom is faster (for 8 bit dav1d is much faster). Probably same problem for mpv. As dav1d matures this problem will be solved.

https://code.videolan.org/videolan/dav1d/issues/216
https://code.videolan.org/videolan/dav1d/issues/78

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Old Yesterday, 00:27   #1873  |  Link
benwaggoner
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Unfortunately it's impossible to use VMAF directly for RDO because an encoder has to evaluate distortion on very small blocks, down to 8x8 pixels. So the best you can do is come up with something that approximates it.
And VMAF isn't THAT great a metric. Many encoders will do some more sophisticated things internally. particularly around maintaining temporal coherence. VMAF does at least include a lightweight interframe comparison metric, but it doesn't do anything new to figure out how the variation of quality of individual frames impacts the overall viewer experience.
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Old Yesterday, 00:31   #1874  |  Link
benwaggoner
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Originally Posted by dapperdan View Post
I couldn't find any x264 tune ssim encodes, but I did find some x265 tune PSNR that show basically the same pattern. Tuning for PSNR at the expense of Fast SSIM, while other metrics don't really change.

The major difference is that the PSNR tuning seems to help with CB and Cr for x265, not just the Y channel.
Well, "help" in the sense that PSNR metrics would improve. --tune psnr reduces the subjective quality of the content at a given bitrate BY optimizing only for improved PSNR scores.
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