Inverse telecine for less common patterns

[franciscola]

I've recently run into some DVD videos that use what looks like 4:2 (4 progressive 2 interlaced) and 3:3 telecine patterns. From what I've been able to gather, these are likely PAL videos that were telecined to NTSC video 29.97 fps. All IVTC filters I've tried produce poor results on this with a lot of judder, and seemingly the only passable solution has been to just deinterlace everything and keep the framerate at 29.97. Is there a better way to handle this issue? Thanks!

[jagabo]

4 progressive : 2 interlaced is PAL to NTSC (6 video frames contain 5 film frames). Use TFM().TDecimate(Cycle=6, CycleR=1).

I think your 3 progressive : 3 interlaced is 6 video frames containing 4 film frames. That would be TFM().TDecimate(Cycle=6, CycleR=2). But that would reduce 30 fps to 20 fps, or 25 fps to 16.66... fps.

[VoodooFX]

All IVTC filters I've tried produce poor results on this with a lot of judder, and seemingly the only passable solution has been to just deinterlace everything and keep the framerate at 29.97. Is there a better way to handle this issue? Thanks!

Post a sample, and you'll get a solution on how to handle it.

[franciscola]

4 progressive : 2 interlaced is PAL to NTSC (6 video frames contain 5 film frames). Use TFM().TDecimate(Cycle=6, CycleR=1).

I think your 3 progressive : 3 interlaced is 6 video frames containing 4 film frames. That would be TFM().TDecimate(Cycle=6, CycleR=2). But that would reduce 30 fps to 20 fps, or 25 fps to 16.66... fps.

Thanks very much for the info. I need to switch to an older machine in order to use avisynth/Windows so in the meantime I gave it a shot using ffmpeg fieldmatch and decimate (which should be essentially the same thing as TFM according to the developer), and as far as I can tell it did a great job. The output framerate I got was 24.975. Is this normal and if so, is it best practice to leave it as is or is another step recommended? Is there anything missing in the fieldmatch and decimate that would necessitate trying again on avisynth/windows? I actually resorted to buying PAL copies of some of these old documentaries because this was driving me nuts and I'm super excited about how this looks already.

[franciscola]

Post a sample, and you'll get a solution on how to handle it.

Here's a one-minute sample of each type (3:3 and 4 progressive:2 interlaced) As I mentioned above, using fieldmatch and decimate cycle of 6 seems to produce a good result and ends up with a framerate of 24.975, which I'm not exactly sure how to handle.

[Alwyn]

Add:

AssumeFPS(25, 1, true)

The "true" should keep audio in sync, as per the AVISynth wiki

[VoodooFX]

Both clips OK with TFM().TDecimate(Cycle=6, CycleR=1). Leave it with 24.975, unless for some specific reason you want it 25.