3:2 pulldown

[kearlywi]

Ive recently been forced to use the "forced film" setting to fix a syncing issue with my cowboy bebop dvd. Now my anime footage runs at 24 fps instead of 30, which is no problem, so far.

I read in EADFAG that 3:2 pulldown can somehow be used to turn 24 fps into 30. My question is, how can i go about implementing this? Is there a filter available for this in Virtual dub? Or a method in AviSynth? Or even an option in Dvd2avi?

[Ashyukun]

I believe that 3:2 pulldown is something you can only really be set when encoding for playback on a TV- specifically, when encoding MPEG2s for playback on hardware dedicated to TV (30fps) output (i.e., a DVD player or some MPEG2 hardware cards). I don't think you can do anything with 3:2 pulldown in AVI files...

[burntoast]

3:2 pulldown is commonly referred as inverse telecine, or IVTC. But it turns 30 fps footage into 24 fps. Premiere should handle 24 fps fine, but I'm guessing that you wanna get the speed back to what it was in 30 fps.. This can be solved simply by typing in this line at the bottom of ur Avisynth script:

AssumeFPS(30)

I dunno whether or not this will butcher ur frames, but it should work.. You can also change the speed in Premiere, based on ur discretion, by using the Speed and Duration options under Clip. Hope this helps..

[koronoru]

3:2 pulldown is commonly referred as inverse telecine, or IVTC.

Actually, 3:2 pulldown and IVTC are opposites. People do animation at 24fps and then they apply 3:2 pulldown (also known as telecine) to turn it into 30fps. You may, depending on stuff, want to apply IVTC (inverse telecine) to get it back to 24. That's where the original poster is at... he now wants to apply 3:2 pulldown again to bring it back to 30. I hope he has a good reason, because it's usually a bad thing to do; it introduces nasty interlacing; but it's sometimes necessary, as he's probably discovered.

There is some additional complication, in that when you're encoding a 24fps source to 30fps in MPEG-2, you can actually do the 3:2 pulldown (turning it into 30fps which you then encode) or you can *not* do the 3:2 pulldown, just encode 24fps, but set flags so that the viewer (DVD player, etc.) will automatically do the 3:2 pulldown itself. That latter approach seems better to me because it's friendlier to progressive viewers, but it doesn't seem to be what most people do in practice. Generally, for other formats, you don't have that in-between option. You have to either do the pulldown, or it doesn't get done.

Note, also, that when I say "24" above I actually mean 23.976, and when I say "30" I actually mean 29.970, but the exact details of why would not be useful at this point.

[trythil]

3:2 pulldown is commonly referred as inverse telecine, or IVTC.

Actually, 3:2 pulldown and IVTC are opposites. People do animation at 24fps and then they apply 3:2 pulldown (also known as telecine) to turn it into 30fps. You may, depending on stuff, want to apply IVTC (inverse telecine) to get it back to 24. That's where the original poster is at... he now wants to apply 3:2 pulldown again to bring it back to 30. I hope he has a good reason, because it's usually a bad thing to do; it introduces nasty interlacing; but it's sometimes necessary, as he's probably discovered.

Wanting to display it on an interlace-scan device is a good enough reason

Although, yeah, if he's using MPEG-2, you might as well just set the 3:2 pulldown flag and let the player (almost all players, hardware and software, that I've seen that handle MPEG-2 can do pulldown) do the work for you. It's easier, consistent, and it saves quite a bit of space, too.

AssumeFPS(30)

I dunno whether or not this will butcher ur frames, but it should work.. You can also change the speed in Premiere, based on ur discretion, by using the Speed and Duration options under Clip. Hope this helps..

That will butcher your project. The two best things to do would be to either just let the format handle it (if it can) or apply telecine AFTER you've finished the whole thing with progressive frames.

Code: Select all

AssumeFrameBased 
SeparateFields 
SelectEvery(8, 0,1, 2,3,2, 5,4, 7,6,7) 
Weave 

That AVISynth script (thanks to AD) will do NTSC-compatible telecine on your video stream. It assumes bottom field dominance, so if your footage is top-field dominant, just stick "ComplementParity" after "AssumeFrameBased".

[burntoast]

3:2 pulldown is commonly referred as inverse telecine, or IVTC.

Actually, 3:2 pulldown and IVTC are opposites. People do animation at 24fps and then they apply 3:2 pulldown (also known as telecine) to turn it into 30fps. You may, depending on stuff, want to apply IVTC (inverse telecine) to get it back to 24. That's where the original poster is at... he now wants to apply 3:2 pulldown again to bring it back to 30. I hope he has a good reason, because it's usually a bad thing to do; it introduces nasty interlacing; but it's sometimes necessary, as he's probably discovered.

There is some additional complication, in that when you're encoding a 24fps source to 30fps in MPEG-2, you can actually do the 3:2 pulldown (turning it into 30fps which you then encode) or you can *not* do the 3:2 pulldown, just encode 24fps, but set flags so that the viewer (DVD player, etc.) will automatically do the 3:2 pulldown itself. That latter approach seems better to me because it's friendlier to progressive viewers, but it doesn't seem to be what most people do in practice. Generally, for other formats, you don't have that in-between option. You have to either do the pulldown, or it doesn't get done.

Note, also, that when I say "24" above I actually mean 23.976, and when I say "30" I actually mean 29.970, but the exact details of why would not be useful at this point.

I really screwed this up.

/me stops posting in these topics..

[kearlywi]

or apply telecine AFTER you've finished the whole thing with progressive frames.

does this mean I have to make an avi (or mpeg2 or whatever) file at ~24 fps THEN take that file and run it through AGAIN using the method you mentioned? (to make it ~30 fps)
Is there anyway to just put it all in the same avisynth code and execute it with just one run?

[klinky]

Export your AVI as 24fps.

Then use AVISource to use it in a AVISynth script.


So it'll look like :

Code: Select all

AVISource("24fpsAVI.avi")
AssumeFrameBased 
SeparateFields 
SelectEvery(8, 0,1, 2,3,2, 5,4, 7,6,7) 
Weave

Take that into VirtualDub, TMPEG and then convert it to whatever you want.

~klinky