speed change quality

FCP-X has optical flow speed change, previously part of Motion 4, integrated with the editing program. It is also in Motion 5.
The optical flow speed change version in Motion 4 left much to be desired quality-wise. Twixtor did a noticeably better job. Andreas Kiel demonstrated this here. Did Apple upgrade this function for FCP-X (Motion 5) or is it the same as Motion 4 had? I ask because if it is now as good as Twixtor's, FCP-X being cheaper than Twixtor could be bought for that function alone.

Twixtor has customization that doesn't exist in Motion or FCPX. The optical flow in Apple's products is based on the technology that existed in Shake. It's actually quite good. It lacks the customization of Twixtor though.

Motion 4 and Compressor 3.5 produce optical flow speed changes each with its own flavor of artifacts. I wonder if they're using the same algorithm with just a parameter being set differently. Twixtor might allow control of that parameter -- hopefully it does more than that.

Now how do Motion 5's optical flow speed changes compare with Motion 4's? And how do Compressor 4's compare with Compressor 3.5's? And what exactly is used in FXP-X?

Dennis Couzin
Berlin, Germany

Only the developers know for sure but I've heard it's all based on the technology in Shake. That doesn't mean changes weren't made in the implementation. I can't see a development team in a company implementing different methods to the same end in a symbiotic product line. I'd expect "core engines" to be the same but end user controls of such might be improved in some products.

I certainly can't speak to whether the core algorithms are better in Twixtor that in FCPX and Motion 5. Twixtor as a specialized tool, has much deeper control. I see the same fundamental issues is optical flow and I don't see Twixtor "automatically" doing it much better. It can certainly do much better with some tweaking but that has its limits based on source material.

I'm not sure there are any radical changes in the algorithm used between previous and current versions of Motion and Compressor. What has changed is that FCPX now uses it whereas FCP7 did not.

Remember, there's a trial of FCPX available so the easiest way of determining the answer would be to try FCPX, FCP7 and Twixtor on the same clip and see which comes out the best.

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Quote
Jon Chappell
Remember, there's a trial of FCPX available so the easiest way of determining the answer would be to try FCPX, FCP7 and Twixtor on the same clip and see which comes out the best.

I agree, but what must be tried are not the three programs you suggest but six: FCPX; Compressor 4; Motion 5; Compressor 3.5; Motion 4; and Twixtor. It would simplify the experiment if we knew the relation of the first five programs in the list. They might reduce to just two. (At least two -- Compressor 3.5 and Motion 4 -- are different, and at most five.)

Dennis Couzin
Berlin, Germany

I think it always depends on the footage.

With some you will get good results with every tool you're using, with some you will get bad or some how good results, with other all tools are bad.
So from my experience you should have them all; by the time you will learn which app to use with that kind of footage you got.

Optical flow can be implemented in the one or other way. In many cases all ways lead to a bad result and you have to start with a kind of visual thinking - means looking at clip and analyze what's moving how. So the first step is to make the optical flow in your head.
When I first time used (bought) Twixtor - after looking at all their demos - I was very disappointed because the results were less good as with other tools with MY material. I talked to them (they had been very responsive) and both of us learned. Based on that discussion they added some features and made me re-think how I've to look at my material.
That lead to a personal workflow which is: you sometimes have to split your footage into layers by masking, export each layer as movie, then retime with same settings and compose. The workflow also might include rotopaint and rotospline.

Again as said above it really depends on the footage, learn about how to look at it and you will find out the best solution; it might be just a drag'n drop or a tedious way.

My 2 cents

Andreas

Quote
Andreas Kiel
...you have to start with a kind of visual thinking - means looking at clip and analyze what's moving how. So the first step is to make the optical flow in your head. ...

Gaining that understanding might be more valuable than having a speed change tool. It sounds like Twixtor (even the demo version) can be a video educational tool.
It would be fun to read your whole correspondence with the Twixtor developers.

Dennis Couzin
Berlin, Germany