Thread: VirtualDub2
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Old 17th October 2018, 05:11   #677  |  Link
WorBry
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Quote:
Originally Posted by poisondeathray View Post
Nearest neighbor should not blur
I was saying that it's the convolution averaged 444>422 sub-sampling that introduces some blur.

Quote:
Originally Posted by poisondeathray View Post
…..It's just duplicating the chroma samples when you go 422=>444 , dropping the exact same samples when you go 444=>422
Which is how it appears on the scopes and checker pattern in the above example where I converted the 'Checker-422' clip to r210 with VDub2.

Quote:
Originally Posted by poisondeathray View Post
So it's a lossless transform if done properly, and you can do it infinite times. Any other algorithm will incur some loss each step, some rounding errors, some blurring which gets worse each successive iteration . But nearest neighbor does not necessarily look good on normal content (blocky color edges), in fact it's considered the worst usually for most types of content. But it's good for test patterns.
Based on the above test series and Shekh's interpretation of the conversion modalities it appears that that is also how Resolve up-samples 422 to 444 on import. Nothing I can do to change that. Resolve processes in 32-bit float, as I'm sure you know.

Quote:
Originally Posted by poisondeathray View Post
No .There something wrong with those last screenshots. Looks like a serious DNxHR issue somewhere in the workflow . Looks like adding some noise or dither . That' s not normal
Which is disconcerting to say the least. I had been thinking about switching to DNxHR_444 as a (Resolve) export intermediate but this has turned me off again. Unfortunately ProRes is not an export option in Resolve on Windows.

If the issue is somewhere in the workflow, then where ? Those blotchy checker board patterns also occur when FFMPEG and Media Composer DNxHR/DNxHD 444 exports (mov and MXF) of the Checker-444 clip (ProRes_4444 and v410 versions) are imported into VDub2, so it can't be something happening in Resolve.
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Last edited by WorBry; 17th October 2018 at 05:51.
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