NTSC to PAL and back

[dukey]

I live in a PAL area and theres a lot of NTSC stuff on tv which has been converted to 25fps.

I often get something like

progressive frame, progrressive frame, interlaced frame, progressive frame ... etc

Assuming the original source was progressive. Is there anyway to convert back to the original FPS ? And if so how would i do this :p

[Fizick]

original=24 ?

[dukey]

well

assuming the original was progressive 30fps
then it was converted to PAL by interlacing

I would then want to try and restore the video back to 30fps from the interlaced PAL.

[juhok]

It's safer to assume it was 29,97i or 24p telecined (http://en.wikipedia.org/wiki/Telecine).

[TheRyuu]

TIVTC? (http://avisynth.org.ru/docs/english/externalfilters/tivtc.htm)
(download here. (http://bengal.missouri.edu/~kes25c/))

For converting 29.97 NTSC material to 23.97p (original), I use this:
tfm(d2v="Sample.d2v").tdecimate()

[burfadel]

Don' they just use Pal speedup with NTSC material in a PAL area?

[Leak]

Don' they just use Pal speedup with NTSC material in a PAL area?
With film material. NTSC material would need to be slowed down to 25 FPS from 30 FPS, and that difference is no longer unnoticeable.

Ergo: blending... :(

np: Phantom Ghost - Phantoms And Ghosts (Phantom Ghost)

[dukey]

i was thinking something more along the lines of
bobbing or FPS doubling every time an interlaced frame is detected

[IanB]

@dukey,

Your 1st job should be to finish analysing your video completely. Separate the fields and determine the field order and the repeat pattern of the fields and look for any blending within individual fields.

Once you fully know what you are working with you can search for rational answers. You should be trying to intuit the history of your source. e.g. 24fps film -> slowdown to 23.976fps -> 3:2 telecine to 59.94i -> field hacking to 50i. Where "field hacking" could be any of hard switching, blending, dropping, etc.

If you have no blending (ghosting) within individual fields there are many field matching technology based plugins available. i.e. Telecide, TIVTC, DoubleWeave/Select*, etc.

If you have blending then search this forum for "Restore24". :search: If you go down this path weigh the value of the source video with how much of your life you are prepared to invest in the project. ;)

[2Bdecided]

As with so many things in life, it depends on what you value more (or have more of): time, or money.

If you have more time than money, then by all means play with NTSC>PAL>NTSC. If you have more money than time, go onto Amazon.com and buy the NTSC release (if available).

Most of the discussions on here revolve around content which isn't (easily) available in its original format. It would be silly to apply these techniques to badly converted content which is easily available in the original format.

I don't have excess of time or money, but getting the original format usually (unless it's messed up) will give the best results, so that's what I try to do. If it's modern high profile "NTSC" content it was probably originated in HD, which would be better still.

Cheers,
David.

[yukichigai]

As someone mentioned, it kind of depends on how it was converted. If you have blended frames then it's pretty damn hard to get back the original frames. (If you look at the Restore24 project you'll get an idea of how complex a procedure it is) If that's the case then there are very few tools you can use to accomplish this, and you're going to have a helluva time figuring out what values to put in once you do find the right tools.

If, however, it's non-blended fields (or even mostly non-blended fields) you should be able to use a combinations of the filters in TIVTC to restore the original frames. (or a close approximation) I suggest you start off with TFM to convert your 25i material to 50p. I use DoubleWeave().TFM(mode=3) or DoubleWeave().TFM(mode=5), depending on what looks better; both have a risk of getting very slow depending on the video, but will come out looking great. Even if you have the occasional unmatched field the cubic interpolation routines TFM uses to bob the fields are really quite good, so much so that you probably won't be able to spot the bobbed frames when you playback the video. Anyway....

After that run it through your favorite comparative decimator to get it to the target framerate. TDecimate is included in TIVTC and works well for most people. You can also try MultiDecimate if TDecimate isn't to your liking, though it takes way more setup to get working.

But that's just my opinion; I suspect someone will come up with something infintely more clever after I post this.

[dukey]

Well, the mix of interlaced/progressive material looks really bad when i encode it with a simple blend.

A straight BOB works but you lose a lot of resolution. Instead of actually restoring the original FPS perhaps could do something like just BOB when there is an interlaced frame ? So the end result would be a variable frame rate video.