fields are driving me crazy

[Goran_r]

When you deal with mixed graphics/video in AFX (and not only in AFX), all "interlaced" material (video - recorded and captured in 50i - PAL, in your case) should be "interpreted" (deinterlaced). So, define interpret settings for all your video clips (be sure about fields order. For PAL - upper field first should be correct ... but check this twice). Also, don't forget to define correct aspect ratios ...
Clips which are "non interlaced" (frame graphics, 3D animations rendered in frames, 24p, 25p, 30p filmed material) - should not be field-interpreted (deinterlaced) in AFX, becaue they contain no fields (and there is nothing to be separated) ...
This way AFX look at all different materials as "all non field", and if you want fields, AFX will generate them on output.
In all other cases "motion, scale and other mathematics" between "PAL/NTSC fields","frames" etc. in same composite - would be impossible, especialy in "general compossiting package" like AFX.
So, for "deinterlacing" Adobe uses its own method which gives generaly good overal results (check "motion detect" tab), and its basic parameters you can set in "interpret footage" dialog, for each clip separately.
Deinterlace process itself can produce different results, depending on used algorythm. If you look at object which is in fast motion, you will notice its position is much different in upper and lower field of same frame. So, merging this two fields will produce full image in full resolution but with too noticable "ghosts".
On other side, using only one field, will use only half resolution, and digital "restauration" of missed lines from "eliminated" field will produce strong "steppings". So AFX deinterlacer uses some mix between this two processes. Mostly it works, but sometimes not ...
To have more controll over deinterlacing, you should try some "smart mask" deinterlace plugins like Revision FX, Tinder Defield or Magic Bullet ... They will "separate" moveing elements and "static backgound" in interlaced shots, and use different deinterlace methods on each to generating full frame. In general - fields are not easy stuff to deal with ...
For your rendering output, you will choose either to render in fields or full frames depending mostly on speed of motion and/or your personal or clients taste.
If you prefere "smooth video motion" (hard video look) - you will render in fields, and if you dont mind little "film look" strobing - you will render in full frames.
If you plan to render in frames, use Motion blur on all animated graphics, and render all your 3D animations with motion blur too. Both (frames, fields) can be played out to your recorder, if resolution, codec and/or aspect ratios are correct (720*576 D1 non-squared for PAL should work). By the way ... telecine process generate basicaly interlaced video from full film frames too, so you can get basic idea what is going on ...

[joconnell]

I'd definitely recommend a copy of reelsmart fields kit for this type of stuff - it's quite cheap and far better than after effects built in de-interlacing.

As for checking fields, I'd recommend a simple test to check which option you need for output. Make a circle about 200 pixels diameter in after effects and animate it going from the top left to the bottom right of the screen over about 200 frames. Render this at upper field first and lower field first form after effects and play it back on a broadcast monitor. The slow move should cause one of the animations to play perfectly smoothly and the other to jitter around like a bastard - Now you know what your filed order is.

As regards when to use either, it depends on what type of look you want. Frames are more flickery and look more film-like and expensive. Fields are much smoother but look a tiny bit cheap. If you are doing 3d animation, frames with motion blur looks best. If this is causing problems, then switch to fields. for motion graphics, frames look best.

[parallax]

Thanx guys,

I sorted it out today, i used the frame blending and motion detection options in AE. Works quite well.
Seems the footage that was shot, was not of the best quality.

now on to the next 10 bumpers :| (deadline in 2 1/2 weeks..)

cheers

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