Using DV on a 24P timeline

[Steve Roberts]

If it was shot 60i, you should not go to a 23.976 (24p) timeline. If you want the speed of the action to stay the same (of course you do) you need to create new frames, new images.

Before you had (basically) 30 images playing per second, but in 24p you have (basically) 24 images playing per second. The images in-between have to be created. It’s like saying you have a ball rolling across the screen in 1/6 of a second. At 30fps, you’d see 5 images of the ball. But at 24 fps, you’d see 4 images of the ball — at different places in the framecompared to the 30fps footage. So you see, the actual images are different between the two frame rates.

The only way to create those intermediate frames, to my knowledge, is to use something like Twixtor to generate those frames. Alternately, Timewarp in AE might work, but I haven’t tried it. Sometimes those effects work well.

I recommend you take the interlaced footage and interpret it Lower field first so you have 29.97 fps footage, but progressive. Don’t change the frame rate to 24 (23.976) — it’s not worth it. Or you could use FieldsKit to remove the interlacing more intelligently. Then you make your new footage 29.97, no fields. Save the 23.976 stuff for all-new projects.

Anybody else?

[Brett Lewis]

Thanks, I will look into the Twixtor plugins etc.

[Brett Lewis]

No its mostly 3D animated stuff, some composited in post also. Its would be awful to crack open all the old files and re render and re comp my history.

I am looking into RE Vision’s Twixtor or Field Kit but cannot decide which is better to buy for the task. Twixtor looks like a fancy time remapping, Field kit looks like fancy de-interlacing… Both look like they can help but I may need both? I hope the company replies soon. I will post the answer once I’ve figured it out.

[Steve Roberts]

If all you want is progressive, not interlaced, why 24P? Why not 30P?

With 30P, you’d just need to use Fieldskit, and there’s no likelihood of strange little distortions when Twixtor tries to interpolate between frames when going from 30 to 24.

[Brett Lewis]

I understand. The thing is I just really want to conform. HD is 24p, Disney etc make DVDs based on 24p If I buy a progressive scan camera it will probably be 24p.
If I stayed 30p, wouldn’t I have problems later on?

Either way I don’t want to convert everything I have twice.

The fact that video professionals brought back interlacing with HD baffles me.

[Brett Lewis]

This is very optimistic talk! The 3D files are huge and over time god knows what surprises will arise.
If you thought After effects took long to render try a couple billion polygons of history.

Thanks but I’d rather stay editing in DV than re render everything from 3D.

[Kevin Camp]

as far as 24p or 30p, disney releases their dvds (hd and sd) as 24p because they were films and were filmed in 24 fps, not because hd is limited to 24 fps.

you can create 30p hd content for dvd and it should actually look slightly better due to the higher frame rate. it will also maintain it’s progressive look if displayed on set that uses fields — the 24p content will get interlaced via the addition of a pulldown to get the frame rate up to 29.97 fps. even though most hd sets are progressive, the 30p workflow would produce better results if you were also outputting for sd sets which are predominantly 30i.

if you upgrade your camera to one that shoots 24p, it will most likely shoot 30p and possibly 60p, so you won’t be limited to 24 fps if you don’t want to be.

there are reasons to work in 24p… film transfers, easy conversion to pal frame rates, and i’m sure a few others, but i don’t think you should feel locked into 24p because the film industry is using it. they are using it because it’s easier for them, not because it’s better.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Brett Lewis]

I do 3d animation. The footage I was referring to might be used for Keying or 3D camera tracking.

I toured Aardman and to my surprise they did not use still cameras. It shocked me too.

[Brett Lewis]

60p! Wow that would be great! Digital slow motion, I did not even know that was available.
I did not know about HD’s ability to do multiple frame rates. It sounds really robust! Wouldn’t the file size and rate jump up huge for 60p!

[Brett Lewis]

Guys I think you are right. 30p is it. I won’t have to re do any of my old clips other than de interlace them. and if I do film 24p in the future, after compositing I can use the pulldown to get back 30p.

At this moment all I deliver on is DVD which is 30fps. From there, MPEG, FLV and MP4 should be easy. Thank you everyone!_B