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Old 2nd October 2019, 08:19   #61  |  Link
Boulder
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Quote:
Originally Posted by benwaggoner View Post
There isn't any psychovisual tuning involved here, so looking at PSNR and SSIM differences would probably be a lot more useful than with other settings.

My gut is a smaller range with HME is probably optimal at fixed encoding time, but it'll be somewhat content dependent. HME is probably more useful to improve perf @ quality than anything else.
Do you think that just setting --ssim would be enough or is tuning needed? I did two quick tests, and at 720p (downscaled from 1080p) --no-hme with --merange 58 was better and at 1080p --hme with --merange 26 was better what comes to SSIM. I did those without changing any other parameters so the psy tunings were there.
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Old 2nd October 2019, 18:17   #62  |  Link
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I also did tests. And with HME results are worse. Video 2000 frames, 3840x1600, HDR. Additional tests a bit later.

Quote:
no-hme
encoded 2001 frames in 1364.38s (1.47 fps), 10941.58 kb/s, Avg QP:21.73, SSIM Mean Y: 0.9838777 (17.926 dB)

--hme --hme-search umh,umh,star
encoded 2001 frames in 1953.88s (1.02 fps), 10773.71 kb/s, Avg QP:21.80, SSIM Mean Y: 0.9837793 (17.899 dB)

no-hme
encoded 2001 frames in 1373.02s (1.46 fps), 10941.58 kb/s, Avg QP:21.73, Global PSNR: 48.476 (w/o --tune psnr Global PSNR: 48.511)

--hme --hme-search umh,umh,star
encoded 2001 frames in 1886.87s (1.06 fps), 10772.40 kb/s, Avg QP:21.80, Global PSNR: 48.449 (w/o --tune psnr Global PSNR: 48.481)
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Last edited by redbtn; 2nd October 2019 at 18:23.
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Old 4th October 2019, 19:28   #63  |  Link
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Quote:
Originally Posted by Boulder View Post
Do you think that just setting --ssim would be enough or is tuning needed? I did two quick tests, and at 720p (downscaled from 1080p) --no-hme with --merange 58 was better and at 1080p --hme with --merange 26 was better what comes to SSIM. I did those without changing any other parameters so the psy tunings were there.
After some rumination, I'm not sure that HME doesn't have psychovisual impact after all. I think there could be cases where it could improve handling of random noise that would have gotten low-pass filtered at the lower resolutions, allowing the encoder to spend more bits on signal than noise.

PSNR would be terrible for measuring this. Not sure about SSIM. Looking at divergence between PSNR and SSIM, or PSNR and VMAF, perhaps could be helpful?
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Old 4th October 2019, 20:41   #64  |  Link
Boulder
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Quote:
Originally Posted by benwaggoner View Post
After some rumination, I'm not sure that HME doesn't have psychovisual impact after all. I think there could be cases where it could improve handling of random noise that would have gotten low-pass filtered at the lower resolutions, allowing the encoder to spend more bits on signal than noise.

PSNR would be terrible for measuring this. Not sure about SSIM. Looking at divergence between PSNR and SSIM, or PSNR and VMAF, perhaps could be helpful?
At least it seems to cause changes in frametype decision. I didn't verify them to be exactly sure, but it looked like my frame-by-frame comparison had often P-frames compared against B and vice versa.
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