View Full Version : Interlacing TV look vs Film look

01-23-2005, 06:14 PM
Sorry if this has been covered in other posts... I just can't find the right info.

Having spent quite some time rendering out a faux tv advert for my company - to be displayed on a large tv screen in the reception, I find that my full frame 25fps PAL animations are unacceptable staggered when something pans past the camera quickly (when finally viewed on an interlaced display via premiere). I've broken it all up into different passes and reassembled it in after effects.

What I want to know is can I turn my existing 25fps footage into an interlaced MPEG 2 without this "staggered" effect for fast/moderately panning items, without having to re-render everthing?

There must be a way because Feature Films source are 24fps- so how do people turn that into something that can be viewed on TV without ths"Staggered" effect (24fps source from film is not interlaced & neither is my 25fps source rendered over a month from lightwave)???

I have gone back and rendered out a small part of the sequence to interlaced output which gives it that "live" tv look which is not the effect I wanted. I wanted that "Film" look you get with full frames

I have also read about doubling the frames output to 50fps (for PAL) and setting the frames to interlace at 25fps in After effects (maximising interframe movement quality) but I really want to keep a "Film" look in this. Will it look like cheap video instead of film if I do this?

Also I am loathe to go down this 50fps route though because I have already rendered out everything at 25fps & dont want to have to trash it all.

Any suggestions gratefully received

01-23-2005, 07:07 PM
i need to ask:

are you saying that youre basing your comments on previewing the output from premiere on your monitor?

if i am wrong, please ignore me, but i wouldve suggested rendering the lot out to DV [av or qt depending on your platform] and exporting to tape.
then play the tape back on your plasma screen or whatever and look at the results.

i never trust anything on the computer monitor. period.

best is to always export, or have a tv monitor hooked up so you can see what the 'final' look will be.

but, if you can, export the lot out to tape and playback on the tvscreen.
ignore the computer monitor and certainly ignore what premiere outputs on your computer monitor!

[i could be wrong so dont stomp on me too hard!!]

i hate the field-rednering look personally, i always go for full frame render..
[and if it needs to be on tv or tape, i render out in frames and export or transfer to a suite where i can dump it all onto tape - or if i'm cheap[!!] i export onto DV and dump it out that way..]

yeah, rendering out in mpeg-2 works - but i only do that if the job requires it on a DVD [mpeg-2 format] otherwise i'd try and leave it at best quality.

01-24-2005, 03:30 AM
Ah yes, I am previewing it on an (interlaced) TV monitor, via premiere and final dvd player playback. I went ahead and did a full mpeg2 encoding & created a project in DVD studio pro on the mac. It not an upper of lower frame issue

This is where I noticed the problem with the moderate to fast pans juddering.

I'm still wondering if I need to rerender for this 50fps manual interlacing trick I've read about or whether I can put my existing 25fps footage through some process (similar to whatever they do to 24fps film footage) to get something that looks good on tv (& still like film).

What do they do with 24fps film when they convert it to PAL (or NTSC) for TV - or is it really choppy for fast pans on tv as well & I just haven't noticed???

01-24-2005, 12:52 PM
When you render with interlacing on, you're effectively rendering at 50FPS, but each 25FPS frame consists of two 50FPS frames interleaved together (it doesn't take any longer than normal because the "two 50FPS frames" are effectively only half-height, and render twice as fast).

What I'm getting at, is that since you rendered noninterlaced, there is motion information that's simply not there, and although it may be faked, it can't be recovered.

You can try to fake it by using post-processing motion-blurring techniques (I've never had much luck with this), but the easiest and most correct way to solve it is to render it out again interlaced. Was the original render that bad? :( If you're on a deadline, maybe one of those rent-a-renderfarms can help?

Good luck! -MG.

01-25-2005, 09:03 AM
You don't have to render interlaced if you activate Motion Blur. Just like film they have 24P but it comes with motion blur, without it motion looks unnatural.

02-03-2005, 09:11 AM
Well I have used motion blur, it's slightly improved things compared with none, but i have a lot of right to left motion in this (kind of like watching a train & carrages pass you at a crossing with a big white background behind them) that last a while so you see that obvious judder as there is no interframe motion.

Is there any point at rendering out 50fps & then interpreting it at 50fps (so it runs at normal speed in 25fps) in Premiere or After Effects if I'm NOT interlacing (on a test I've done it doesn't seem to be using those interframes I've rendered at all - might as well stick at rendering at 25FPS)

I just want to soften the change between frames without turning it all into a very blurry mess. Maybe if I change the background colour to something darker it will hide the stepping more (but I doubt it)

02-03-2005, 10:31 AM
I don't use Premiere or After Effects, I use Digital Fusion and it can be done what you are looking for. I have never tried but I know that you can use Lightwave to do frame rate conversion, just bring your frames as a backdrop (Effects panel Compositing tab Background Image) set your camera to same resolution and aspect ratio as you had for your scene and set frame rate at 25. It should work

Jack Tinsley
02-05-2005, 09:13 AM
An animation can look fine as long as it isn't moving quickly and be the wrong field order. Try changing your field order (odd to even or even to odd).