IVTC of 720p material?

[minchjp]

Hi, i have a 720p60 recording (mpeg2, ts) which contains film material. I want to convert it to 720p24 without having to re-encode (kinda like what you would do with an avi file in virtual dub). Is this posible? If so, how do i do it?

Thanks

[manono]

Is this posible?

No.

[cavalierlwt]

It can be done via AVIsynth, but it's potentially a lot of work, quite a learning curve as well.
The issue is this: They broadcast 720P HDTV at around 60FPS in the US, 50fps elsewhere.
Essentially they take the 24FPS and do some weird 3:2 telecine conversion.
In theory, it would go 3 repeated frames, then 2 repeated frames, over and over.
Like this:
AAABBCCCDDEEEFFGGGHH and so on, converts 24fps into 60fps.
In order to get back to ABCDEFGH....
you need to decimate those repeated frames, leaving only unique frames, each frame displayed once at 24fps. In a perfect world they would stick to a pattern of 3-2 3-2 3-2 and it would be easy (occasionally it is). Unfortunately these patterns vary wildly which makes things very tricky. I've just started learning about it, but there are other posts that deal with it.
Do searches on 720P and AVIsynth and you'll find info. I think it's quite a pain in the butt so far, but IMHO material looks so much better, smoother at 24fps than some weird random pattern of repeating frames.

[manono]

It can be done via AVIsynth,

Of course it can:

SelectEven()
Decimate(5)

But that's not what he asked. He asked if it could be done in VDub without reencoding.

[cavalierlwt]

Oops, I missed the reencoding part, I guess I was too focused on my own problem regarding 720P60-->720P24.

As for
SelectEven()
Decimate(5)

Good luck having that work on a recording of 'Lost'
They are all over the place with nary a repeating pattern in sight.

[manono]

There are plenty of other ways to do it, if the patterns are irregular. I don't cap anything so I haven't played with it much. I've just seen a few very short clips from Lost, which seemed OK. If you need any help or suggestions, just upload a small section somewhere that shows the problem.

[cavalierlwt]

Thank, I'll write up my problems when I have bit more time, maybe upload a clip.

[cavalierlwt]

Well, I found the problem. The program I used to cut out commercials and save as mpg-II somehow messed up the timestamp of the file, causing it to have the right number of frames but listing the time length as too short--effectively changing the framerate upwards a bit (even though it still listed the framerate as 59.940).
When I attempted to used FDecimate with a rate of 23.976, it would occasionally drop a unique frame because it was reading through a file with a slight mismatch between timestamped length and actual length (fps x number of frames).