Quote:
Originally Posted by Sharc
This brings the quality (and artefacts) of the deiterlacer into the equation.
For temporal and temporal-spatial filters it may be preferable to
separatefields -> even/odd grouping -> filter the even and odd fields -> interleave -> weave.
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It may also degrade quality if processing will operate with some 'vertical direction' . For example MDegrain(N) try to move blocks and interpolate in both V and H directions and possibly may add more distortions.
Also some 4:2:0 interlaced processing may used 'mixed' block types - some blocks are treated as interlaced and some as progressive (to have better vertical colour resolution that degrades to 1/4 instead of 1/2 for progressive 4:2:0). When separate to fields - the 'progressive' blocks lost Nyquist limiting as being point-downsized 1/2 without pre-filtering. And later processing may cause additional distortions.
It is better to try both processing ways - with converting to progressive full frame height and with processing separated fields as progressive and pick best output.
Changing default interlaced to 'true' will degrade vertical colour resolution if processing progressive scanned frames. And as Avisynth was designed by PC programmers and not old video (moving pictures) engineers - PC (usually static) bitmaps typically progressively scanned so default interlaced was false from the initial Avisynth design I think.