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Old Today, 09:40   #681  |  Link
shekh
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From the screenshot it seems Sony is using bilinear downsampling for 444->422, this blends max 2 neighbor pixels as opposed to summed area.
I changed various interpolation options until I got very similar picture.
For 442->444 it is still bilinear upsampling, no changes.

Last edited by shekh; Today at 09:42.
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Old Today, 13:58   #682  |  Link
WorBry
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Thanks again Skekh,

Just to be clear about VDub2:

Quote:
Originally Posted by shekh View Post
Checked what is going on with chroma,
444 -> 422: each pixel is convolved with kernel 0.25, 0.5, 0.25
As I understand this creates some blurring.

422 -> 444: odd pixel is copied as is, even pixel is blended from two neighbor source pixels
This is simple.
So is the 422 > 444 in VDub2 (by definition) Nearest Neighbor (Point) up-sampling, which is how I first interpreted your description, or Bilinear upsampling ?

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Originally Posted by WorBry View Post
So, if I understand correctly, its 'nearest neighbour' (point) up-sampling and it's the convolution averaged chroma sub-sampling that brings about the separation of the R/B and G channel plots on the Resolve Parade scope, which manifests as blur ?



Up-sampled in that example to r210, because Resolve wont import v410
As regards Resolve; actually prior to 15.1.1 version update, the v210 'round-trip/pass-through' behavior (using the 'Checker-422' clip) was different



The change in behavior seen in 15.1.1 came in response to concern (from BMD forum members) about the quality of the export 422 sub-sampling:



Which is when it became apparent that the 'new' behavior bore a striking similarity to that seen in VDub2 for 422 > 444 > 422.

In fact, referring back to the series I posted earlier....



....when I ran quality metrics (FFMPEG) on the matched v210 exports from the Resolve and VDub2 series, the SSIM scores were 1.000000 (lossless) for Luma and UV chroma.
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Old Today, 14:50   #683  |  Link
shekh
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Quote:
Originally Posted by WorBry View Post
So is the 422 > 444 in VDub2 (by definition) Nearest Neighbor (Point) up-sampling, which is how I first interpreted your description, or Bilinear upsampling ?
Bilinear. Even sample is centered so it is not blended but odd sample is blended.
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Old Today, 15:10   #684  |  Link
WorBry
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Thank-you Shekh.
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