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View Full Version : Fields, framerates and general no-no's


JamesMK
06-15-2003, 12:46 AM
Just want some input here, and I figured this would be the appropriate place to ask::..

I'm going to start rendering the first shots of a rather big project in a couple of weeks, and I have started thinking about what approach would be the best for me... I did search the forums for this, but feel that I still lack a straight answer, sort of...

Anyway - the Question! I'm making this all-CG movie, and my current plan is to render full frames (no interlacing/fields) at 24 fps.

I have three reasons for this:
1) I get that 'film-feeling' which I like,
2) It will not look strange and 'fieldish' when watched on a computer screen, and
3) it saves a lot of rendering time.

Since I basically lack any kind of solid "industry experience" I would simply like to know your view on this approach. Is this a good idea, or will I live to regret it somehow? Need to know!

Chris
06-15-2003, 04:21 AM
Whats the final media? Film, vcr, DV?

Its really up to you, if you are after 'that film look' - ie stattaco looking fast action, then you are heading down the correct road. Personally I would render to 50p - that way you can introduce fields for 25fps VCR/DVD/DV , or remove every second frame to get 25p, which you could play back at 24p for transferring to film. But then again, thats going to push up your render times, which you may not want. Also if you are on NTSC, its more of a problem, as you would be rendering to 60p - which would need pulldown added when transfered to 24p film (after downconverting to 30p)

Mazer
06-15-2003, 06:51 AM
Don't now if its the kind of awser you are looking for, but in a recent job using Maya, we used this solution for the fields:

we animated at the normal pal framerate and resolution, then we doubled the sise of the animation, we divided the vertical resolution by two ( ie 640*480 go to 640*240 ) and set the pixel aspect ratio at 0.5, the result is like if you took the original frame and scaled-it to 1/2 hight in photoshop, and it renders at aprox alf the time.
Finaly we assebled the fields with a maya utility caled field assembler.

JamesMK
06-15-2003, 08:06 AM
Thanks for your answers so far!

And, well, the final media would simply be a compressed AVI :D, but it's quite likely that I may want to transfer to DVD too.
Real film is not going to happen, since this is mainly a personal project. I will make one full-length version, and one shorter to serve as a demo-reel.

Rendering to 50p (that would mean full-frames, right?) and then simply remove every second frame for the AVI-version sounds like a practical solution. The only problem would be render time. My hardware is sort of the opposite of a renderfarm - one single and really slow computer :scream:

Now, if I would go for 25p, and introduce fields for DVD/VCR by duplicating frames - would that look very horrible, or just look like any movie originally shot with standard 24p analog film?

danylyon
06-15-2003, 12:45 PM
Originally posted by JamesMK
Now, if I would go for 25p, and introduce fields for DVD/VCR by duplicating frames - would that look very horrible, or just look like any movie originally shot with standard 24p analog film?
Well you're not duplicating frames. You're just putting one frame on two fields.
And.. don't do fields.. it's so ugly!
I'd recommend rendering at 720 x 576 and 25fps (for PAL / DVD), with a decent Motion Blur.
Also.. take care of action and title safe if you're outputting for TV.

If rendertimes are an issue then you could:
- render at 16:9 (with black on top and bottom)
- render at a slightly lower resolution and blow it up in post. (3D graphics are normally anyway too sharp, and the DVD compression would eat up a lot of info aswell)
- if you're only making a VCR.. I think you only need half the PAL resolution anyway (I'm not sure here though).
- Make motion blur in Post
- Render in layers (always a good Idea)

hope that helps..

JamesMK
06-15-2003, 04:34 PM
Originally posted by danylyon
Well you're not duplicating frames. You're just putting one frame on two fields.
Yeah, sounds more reasonable... This clearly indicates my current knowledge in this particular area :D

And.. don't do fields.. it's so ugly!
That's exactly what I think too. I wasn't sure if I would paint myself into a corner by simply staying away from it...

If rendertimes are an issue then you could:
- render at 16:9 (with black on top and bottom)
Yes. That was the one thing I was already sure would be a pretty safe measure. And it looks cooler too.

- render at a slightly lower resolution and blow it up in post. (3D graphics are normally anyway too sharp, and the DVD compression would eat up a lot of info aswell)
Sounds intriguing, for sure! Expressed as a percentage - about how much enlargement could be reasonable without apparent qualityloss?

- Render in layers (always a good Idea)
Yep. That is now an official entry on my todo-list...

hope that helps..
It sure does, thanks a million!

danylyon
06-15-2003, 07:43 PM
Originally posted by JamesMK
Expressed as a percentage - about how much enlargement could be reasonable without apparent qualityloss?

Hard to say.. I've never outputted for DVD only. A broadcast job I did recently, I rendered at about 90% (can't remember exactly).
The problem with this approach is, if you've any kind of bad antialiasing.. they'll be much more visible.


Good luck!

JamesMK
06-15-2003, 08:08 PM
Originally posted by danylyon The problem with this approach is, if you've any kind of bad antialiasing.. they'll be much more visible.
Ouch! Thank you for adding that, saved me some time I think - the renderer I'm using has slightly-less-than-perfect antialiasing filters.

I'll be on my way, then. Thanks a lot for your answers, everyone! :thumbsup:

arvid
06-16-2003, 02:03 AM
I'm with you on the field-issue, I always try to stay away from field rendering, and if your final format is AVI's you don't need them at all :) At work I always render out my final sequences as PAL frames, but our stupid editing suites drop the second field if I do that (don't explicitly specify that fields are on), so I have to re-render the finished movie to fields (effectively putting 1 frame in two fields) so I don't lose all that resolution, and still get the desired 'film-strobe'. When you play something through video you cant escape the interlaced nature of how video is built, but you can work around it :) If you cant afford to render motionblur in 3D take a look at ReelSmart Motionblur, it does a pretty good job at adding motionblur to an existing sequence, and motionblur is important for the film-look :)

JamesMK
06-16-2003, 08:36 AM
I guess I'll have to stick with motionblur in 3D. This movie is a sub-shoestring budget thing, so I couldn't go with ReelSmart even if it looks like a clever solution.

Since I will be rendering in layers, I suppose I can get away with motionblurring only those layers that actually contain motion, leaving static backgrounds to render just as-is. But it sounds like I definitely need motion blur to get the desired "feel" then... Thanks, opacity!

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