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After Effects and Twixtor 4.5 – too ambitious?
Hey everyone!
I’m calling on the collective expertise here to figure something out that has me boggled…
I’m working in AE6.5 Production bundle and Twixtor 4.5. I am creating a split screen composite of two PAL HDV shots. Each one is one take (one is about 12 minutes, the other is 14 minutes long) that need to be time remapped to sync to each other at numerous points throughout. The final length will be about 10 minutes. I’m using Twixtor to do the remap and have questions about the calulation of vectors, motion blur compensation, and render time.
I did a test at full resolution, with motion blur compensation set to .5 (as the manual recommends). I had the motion vector calculations set to full, and the frame interpret set to motion weighted to smooth out the “softening effect” – I turned on frame blend (to allow Twixtors effects to be active) and motion blur (I also did some image stabilzatin by keyframing the position of the video layers behind their mattes) in the After Effects timeline and was shocked that I was getting an estimated time of 85 hours to render a 4 minute work area – mind you – that was just rendering the two shots crudely composited! At over 55 seconds a frame thats about 275 hours to render just the twixtor effects! (about 18000 frames) On a dual 2.5 with 2.5 gigs of ram, is that ridiculous or is that just what’s it’s gonna be? One thing I feel I should mention is that right now I’m working with a demo of Twixtor 4.5 to test before a purchase – is that having any effect other than the watermark?
I guess what my question boils down to is a settings and workflow one. I recently created photo-jpeg proxies at a third res to aid but the benefits are nominal. I believe that I have some settings unneccesarily turned on both in Twixtor and in AE. Does motion blur really need to be enabled to allow twix’s motion blur compensation to work like frame blending needs to be on for twixtors’s blending to be active? How would you all approach a project like this with a daunting render time awaiting? I’m starting to think that I should do all my color treatments first and twixtor those because the render time will just be too damn long! I’m frustrated because the time remap has be perfect for the project to work but the sluggish response is killing me? Is there any way to work on the sync in one pass and then do another pass to ensure smooth blending throughout?
I apologize for the stream-of-consciousness type post but the questions are endless! Any help would be greatly appreciated!!
Thank you so much!!
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4 Replies
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Well, not considering all other issues for the moment, I’d say the rendering times are quite normal if you have the effect apllied to the clips as a whole. It’s definitely not a limitation of the demo (though I think you only get multi-thread support on full purchase).
You have to understand that it’s really a strict per-pixel evaluation (and at HD res that’s a lot of pixels to take care of). The greatest impact have the settings for the temporal evaluation – the more frames you figure in, the longer everything takes but the better usually the result is. So basically you should check across how many frames you really need to do the analysis. In addition to this, you should slice your long shot in separate sections and only apply Twixtor to the parts that need retiming – frames that Twixtor doesn’t see won’t be analyzed and render at normal speeds. You only need to take care of adding some handle frames at the start and end and make sure that the last and first frame run at the original speed. You can easily blend everything together then.
Motion Blur compensation is not necessarily a must-have. It’s a huge render hog, but does not always improve the result. If you need to use it ultimately depends on your footage.
Mylenium
[Pour Myl
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First, let me clear up a misconception: The difference between the demo and the full version is the watermark. That’s it.
Now, as to Twixtor and the calculation time you are seeing
1) You can set Twixtor’s motion blur compensation to 0.0 if you don’t need it. All that setting does is a) add motion blur if you are speeding footage up and b) remove motion blur if you are slowing footage down. If you are not changing speeds by a large amount, then setting this to 0.0 will be fine (do a comparison test on a couple of frames… if you don’t see enough of a difference, then you don’t need it and it is unnecessarily slowing you down).2) Twixtor’s motion blur is meant to *replace* the motion blur found in AE. So you’ll want to turn off AE’s frame blending for the clip/footae that has Twixtor applied to it.
3) TURN OFF AE’s Frame Blend for the comp/clip with Twixtor applied. Twixtor works independently of AE’s frame blend and having the two on at the same time is unnecessary (and will produce incorrect results).
4) 55 seconds a frame is not the standard amount of time for Twixtor to process two PAL HDV-sized frames. It should be more on the order of 3 to 10 seconds (depending on whether you use Twixtor’s motion blur compensation, and the amount of movement in the scene). Of course I don’t know if your 55 second timing takes into account all of your other filtering/editing that you are doing on the 2 clips. I just did a test on my 1.5 Ghz G4 single processor laptop and it was taking 6 seconds for 1 1440×1080 frame, with motion vectors set to “Best” and motion compensation set to 0.5 and the interpolation set to “Motion Weighted Blend)”. So for one clip on a 2.5Ghz dual proc G5 I suspect that it should take about 2 or so seconds a frame. This timing isjust for the Twixtor processing… this does not include reading the frames from disk or any other processing you are doing on the clips. ALSO, if you do not have enough memory to hold 2 HDV frames (Twixtor needs to get 2 frames for each frame it makes), plus extra memory for Twixtor, perhaps you are thrashing to disk?
5) Workflow tip for using Twixtor when interacting: set Twixtor’s Motion Vector setting to None (you’ll get something equivalent to AE’s frame blending) when keyframin the frame number of speed setting. Most definitely set motion blur compensation of Twixtor to 0.0. THen, when going to render, turn the Motion Vector Setting to “Best” and the motion blur compenation back to what you wanted (0 or 0.5 or whatever). ALSO, when interacting, I would turn the interpolation type from “Motion Weighted” to “Blend”. Again, when going to render, set it back to Motion Weighted. Doing these 3 things will improve interactivity immensely (and then setting them to their required setting for rendering will get you the high quality results you want when going to disk).
[Mylenium] “In addition to this, you should slice your long shot in separate sections and only apply Twixtor to the parts that need retiming – frames that Twixtor doesn’t see won’t be analyzed and render at normal speeds. “
You don’t really need to slice up your footage. Twixtor only does motion analysis if the speed is not 100% at a particular frame (100% speed is figured out internally, and the skipping of motion estimation step at 100% speed applies whether you are using either the Speed or Frame method of retiming inside of Twixtor).
Hopefully this answers your questions,
Pete Litwinowicz
https://www.revisionfx.com -
Argh. I said:
2) Twixtor’s motion blur is meant to *replace* the motion blur found in AE. So you’ll want to turn off AE’s frame blending for the clip/footae that has Twixtor applied to it.
and I meant
2) Twixtor’s motion blur is meant to *replace* the motion blur found in AE. So you’ll want to turn off AE’s motion blur for the clip/footae that has Twixtor applied to it.Pete
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Hey, thanks for clearing things up. Haven’t been using Twix in ages (think it was v3 at another company) so it’s quite possible I’m not up to specs on it.
Mylenium
[Pour Myl
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