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How to get 25i from 50p in AE
Hello 🙂
for reasons, that are not part of the problem I need to separate the fields of interlaced footage. But how can I get a interlaced clip again as endresult ?
Here is my workflow so far.
1. Import interlaced footage and check for correct, interlaced interpretation.
2. Make new comp twice as long as the clip.
3. place the clip in the timeline and timestretch it to double length.
4. Do my work to the clip (which now shows me all fields as “real” frames and therefore is a 50p clip in a 25 frames composition, which makes trouble soon)
5. render that out as a 25p clip.
6. Import into Premiere (interlaced 25p Project), double the speed of the clip (with no blending option) and here we have a interlaced clip again.
I would like to do step 5 and 6 also in Aftereffects.
But how ?Thanks for any ideas!
Peter
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8 Replies
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Hi 🙂
Thank You, but I am aware of interlaced video and how it is treated in Aftereffects. 🙂
Still there are several reasons that one would want to go the way I described. One example would be masking interlaced footage which is otherwise impossible in AE, as the Masks are used for both fields at once, which leads to wrong masks on fast movement.
I think I remember even, that I learned that workflow from the cow :)for mask problems.My actual problem is a complex thing with downscaling from HD 1080i.
I have to go from 25i to a doubletime 25p with interpolated fields.
My question ist:
How can I intermix that again after Work is done to the single-field-frames into a “normal” 25i ?Thanks!
Peter
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[Dave LaRonde] “It’s not as complex as you think: find the scale property and use it. As long as field order for everything is interpreted correctly, you’ll be good to go.”
Sorry – no 🙂 If you follow all the threads that are around in HD forums, downscaling interlaced HD material is not that easy. But that’s still another topic. If you simply downscale in AE the aliasing will be inacceptable. And adding a simple vertical blur will not help.
[Dave LaRonde] “An animated mask actually moves and changes its shape from field to field. If you have a keyframe on each frame, the mask will change on the intervening field. “
True – but that doesn’t help if the motion isn’t consistent over fields. That is when the field separation comes into play.
Anyway – Your idea with a 50fps comp is good. But then the timebase must also be changed to 50. I tried that. But it doesn’t give the same good results as the double time-stretch technique with re-interlacing in Premiere.
So has anyone a solution for the initial question ?
How can I make a render out of aftereffects, that makes the clip double speed and doesn’t throw away each second frame, but intermixes them to fields ? No, not frameblending 🙂 Fields.
Thanks!
Peter
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After Step 4,
drag that comp into a new comp,
make the new comp half the time of the comp in step 4,
speed up the comp (as a layer) from step 4,
and render interlaced out of after effects.in other words… reverse your workflow after step 4
cya,
Jan
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IF it is as you’ve said in the threaad title, starting with 50p assets and going out 25i, then these are the steps yo ushould take –
1) Interpret the 50p assets accordingly, ie as 50P
2) Create a new comp with the same duration as the asset but with 25fps.
3) Drop the 50p footage into this comp. Your asset should place itself into this composition without losing any time (duration) – ie it should maintain its original duration.What’s happening is that each of your full-rez frames is now being placed as an interlaced field. If you were to now output this comp with ifieled ordering (25i), you should get the same duration as the original asset and actually increase the vertical resolution of your footage since each field is now created using a full-rex (full-frame) image.
HTH
RoRKbroadcastGEMs.com – the leader in customizable royalty-free animated backdrops
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In the olden days before many 3D apps could render fields, we produced scenes that were twice as long. We would interpret the clip at twice the frame rate and, when dropped into a field-interpreted project, AE magically separated the frames and combined them into fields.
Your workflow description makes no sense to me at all. Far too many steps, way too complicated.
And I’m here to say thanks to Dave LaRonde for having the patience to try to get you to explain what you needed.
bogiesan
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I think you’re looking for reelsmart’s Re-interlacer that fixes the problems you are discussing.
< Half Frame Rate: This option takes each 2 pairs frames from the source and makes 1 frame by taking the field scanlines specified in Fields Order from the first frame of the pair, and the field to be displayed second from the second of the pair. This option assumes that your source material is at one rate (say 59.95 fps) and the destination is at half the frame rate (in this case, 29.94 fps).This option only works in After Effects, Combustion 2.1 or later and Commotion 3.1 or later. • < Keep Frame Rate: This option takes each 2 pairs frames from the source and makes 1 frame by taking the field scanlines specified in Fields Order from the first frame of the pair, and the field to be displayed second from the second of the pair. However, this option makes the destination 1/2 the duration (so 4 seconds of input becomes 2 seconds of output). • = Field Blending : Field Blending is mixing two fields from pairs of images in a sequence. This option neither creates nor destroys frames, but rahter, blends fields of adjoining pairs of frames in a way that may be less-flickery on an interlaced monitor. This is a useful filter when your source material has small animated things (like stars) or horizontal lines that move about an image. Note this is a destructive process in the sense that you will not be able to deinterlace that render to recuperate the exact original source. • = Combine: Say you have two sequences of whole frames aligned in time. One sequence if of whole frames that should represent the first field of the output and the other, the second field. Apply Reinterlacer to the sequence representing the first fields, set the source to the other sequence that is to make up the second fields of the output. • = Create motion estimated fields: This option will convert progressive material to interlaced material using motion estimation to create new fields between each original frame. This mode looks at the current frame and the next frame and estimates a new field at the inbetween position. Looking at the current frame and the next frame can create some issues at a cut point in your sequence. In applications that supports animation of menu options, you might need set a keyframe at the beginning of a cut. This mode is helpful to get a consistent look when merging material without fields and material with fields (or simply generate a field based render in a progressive project…) .
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Hello 🙂
Chris: thanks – I have the reinterlacer 🙂 Somehow I forgot about it, as I always only use the De-Interlacer.
Finally the solution is drop the 50p into 25 and render out interlaced. So simple.
Thanks for all Your ideas. They all seem to work.
And for those that don’t understand the reason for doing so:
You will understand as soon as you have problems with aliasing when downscaling 1080i footage.Again thanks to all!
Happy New Year!
Peter
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[Dave LaRonde] “Considering the many, MANY people who use (and scale) HD footage in this forum –“
Sure You’re right.
That’s why I asked here, where the specialists are 🙂[Dave LaRonde] “those who work with 2K comp sizes”
Those are mostly going back onto film and don’t get downscaled.
[Dave LaRonde] “and considering you’re very first person to report problems of this kind….”
No, but believe me, not everyone has that much experience.
If You follow some camera forums, there are big discussions about this problem. I meanwhile found the solution for me – with all the helpful replys here.So thanks again!
Peter
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