As for IVTC, I haven’t tried Avisynth yet but I’ve read about it and would try it. I am aware of the change of pattern that can happen but I think that could be the case with any algorithm. As you mentioned, doing those by hand to produce progressive results is the best way to have perfect results but I don’t see how it can be fast. Shouldn’t that take forever? Please elaborate on that.
The speed of a hand-made IVTC in avisynth (using SelectEvery) is lightning fast. But I think you meant to produce the script. The script that handles the different patterns by hand can in most cases (>99%) be made in about 15-30 minutes. There are only three patterns in 99,5% of all cases, the only exceptions of this I had with Japanese NTSC-sources so far, they sometimes have a different way of pulldown, but also not often.
So, you just have to specify those three patterns, handle them with variables, and put all together with Trim’s.
A question of how exact you want to have your result. In a professional setting, where you have to do IVTC for series with >100 parts, you sure wouldn’t do this by hand, but if you do something with love - as everybody here does, I think - and willing to spend some time more to achieve the very best result, it’s no question, is it?
I can only encourage you and everyone to try avisynth. It’s the most flexible thing to handle video out there, and you have FULL control of what’s happening.
Second, I’m not sure I understand the part you talk about telecining while scanning.
If the original footage has been 24fps film/animation and telecined (3:2 pulldown) to 29.97fps which is the case with Laserdiscs, IVTC is the process to get rid of those added frames and turn it to 23.976fps. The results should have no jagged edges or as you say staircase-artefacts and no half resolution. My IVTC video has no rough edges if that’s what you mean, so please explain this.
This ugly pulldown-thing that you have with NTSC (I am lucky to live in PAL region) is produced in different ways. Sometimes while scanning as one process (older sources), or later. But this is not the point of what I meant.
The point is compressing while interlaced. Maybe this Laserdisc-source comes from an older scan. At a very early “stage” it has been copied to a - let’s say - DigiBeta-cassette that then was archived. DigiBeta-format is quite good, but compressed, not much, but lossyly compressed. If the source copied to a DigiBeta is progressive, you won’t notice the compression with your eyes, no chance. But a pulldowned source is combed… The most ugly thing with pulldown is, that in almost any case you do not simply add frames by doubling every fourth, no - it’s fields that are added - as you know of course - that results in combing. Lossy compressions - reagrdless of how good they are - do harm in these cases. Let me specify:
film --> scanned with pulldown (telecined) --> stored really uncompressed or losslessly compressed --> IVTCed
would give you 100% progressive frames back, that’s right.
film --> scanned with pulldown --> maybe once stored uncompresed --> copied to and archived as DigiBeta --> even copied to another medium via SDI or similar interfaces --> IVTCed
will result in small jagged edges (thanks for the term), that increase with sharpening, even with AI. There is no lossy compression algorithm that does not produce ANY edges when handling combed material. You won’t notice it in most cases, but you will see it, if you sharpen, and that’s what is done here.
The later the Pulldown happens, the higher are chances to get more or less artefactless original progressive frames back.
Below are the images. It’s best to download and see at 100% but you can still see the difference here.
These look damned good! One could critisize many things, but to my feeling they really look good. I only doubt that this couldn’t have been achieved also with more conventional things than AI - and I doubt that GP doesn’t take advantage of these. 😉