Interlacing frustration

[Mr.Herron]

I apologize in advance for ANOTHER one of these threads, but I've been searching for days trying to find an answer but each topic that discusses this doesn't seem to relate to the answers I'm looking for.

Since I've had the camera I've been shooting all my footage in 24pN and 30p, depending on what it is I'm shooting. If I'm out at the races, I shoot 30p and can pull a perfect image with no issues at all when I export. I capture in FCP with the DV-NTSC default setting, cut the project together, and then export and have no issues with interlacing lines at all. In fact, the image is perfect.

Now, I just shot some footage yesterday for a short in 24pN and when I export, it's extremely interlaced. I'm using the exact same settings I use for when I shoot 30p footage, except this time the image produced after exporting is terrible.

What did I miss? I was always under the impression that 24pN and 30p footage were both played back at 29.97fps. So wouldn't this mean there shouldn't be any difference between the two when I export them? I'm editing on a 29.97 timeline for both, which I assumed was the thing I needed to do. Is it just a matter of the way 24pN footage is? I've noticed every 4th and 5th frame are the only ones that are interlaced, so is that just part of the pulldown used to generate the 24p "look" on 29.97 footage? And if so, how exactly do I go about removing that? Do I have to bring it through cinema tools or something of that nature?

This is just extremely frustrating and it seems to be a constant hit or miss. I've shot 24pN footage and it looked great, and other times...like now, it looks extremely interlaced. I'm not entirely sure what it is that I'm doing wrong.

My settings are currently
Capture - DV/NTSC default
Sequence - DV/NTSC default

Is there another setting I need to change somewhere? My mind is just all over the place right now, and I'm not even sure where to begin.

I apreciate any and all help.
Thanks
-Josh

[Xtopher]

thats odd.... did you deinterlace in the export dialogue? sometimes that can help... but its weird that you have any interlacing at all...

[AwakenedFilms]

Mr. Herron,
I am a lttle confused. If you shot 24pn, there would be 24 discrete progressive frames per second. If you edited the 24pn footage in a 60i timeline, it is likely that you will indeed have problems.

What camera are you shooting on? DVX? HVX/HPX?

As far as I am aware, the DVX does not record 24pN. The HVX/HPX does record 24pN, but should not be capture within a 29.97 frame rate.

The DVX records 24p and 24pA, which should be captured in a 29.97 frame rate and then the pull down or duplicate frames removed.


More info may help diagnose the problem...


Jason

[ullanta]

24pN indeed has 24 discreet frames per second (23.98, to be exact). That means that, in a 29.97 timeline, the 24 frames have to be "padded" with additional frames... one extra frame of padding for every 4 "real" frames. To make this playback as smooth as possible on a 29.97 TV set, the extra padding takes the form of duplicate fields, interlaced into the stream. The addition of these extra fields is called "adidng pulldown." On a CRT TV this looks pretty smooth. On a progressive device (like computer monitors, and most modern non-CRT technologies) it looks very interlaced.

24pN (or 24pA) should be edited in a 24fps timeline. Editing in a 30fps timeline will add these interlacing artifacts.

30p, btw, is no different from 60i in the way the NLE handles it... there's no "padding"; it's just a matter of the order in which the fields are captured.

[Mr.Herron]

That's the answer I was looking for!

Thanks so much!