Frame blending: Retiming/Variable Speed/Tracking ?

Hi fox. Thanx for helping.

1) I understand that the video will play at the same apparent speed, but if I play a 30fps in a 50fps project, is there not a lack of data for it to be played in the same conditions as in 50fps? Or do you mean that Motion keeps playing each and every clip at their individual speeds regardless of the project's fps (Then a slowed down clip (which is advised to be played with frame

blending) is slowed down if and only if it is played at a ≤100% speed)?

2) Maybe I should explain better what I usually do, frame blending or not. With Variable speed activated, let's say in elementary math terms that the function is the basic identity: f(x)=x. Variable speed has two natural keyframes programed: f(start)=start and f(end)=end. If I notice that frame y is flawed (as may be the case with time-lapse clips for instance), I just type (with Keyframes): f(y-1)=y-1 f(y)=y+1 and the minute speed discrepancy that ensues is compensated for over the rest of the clip because f(end) remains equal to end. I do this with every flawed frame and may even skip more than one in a leap. It appears seamless when it plays, at least to my eyes and with the footage I've used...

3) Motion seems to refuse any kind of tracking on a clone of an optical-flow-ed clip, or even a group made of it... Don't know why, but I had to export in 50fps first.

4) In Motion 4, I have good results with Optical flow and mediocre ones with Frame blending. Maybe Motion4 predates the changes you're talking about.

My bad: my Motion version is 5.4, not 4. So, yes, Optical flow doesn't give this morphing effect anylonger (I tested it in the reproduced context of this video of yours) and I agree it's a pity. Anyway, Optical flow still provides good results in very much slowed down clips at least to my eyes (see [0'36 - 0'56"] here https://youtu.be/0GrZBO8X8fQ where the clip with the buildings is 29.97fps played at 35% speed in a 50fps project, whereas the simple frame blending option did an AWFUL job).

As to tracking, I've come across some cases in which your methods (including the bezier line) are indeed better than automatic tracking: when the movement curve is clear with no fits and starts, no incessant back and forth, and no detailed stabilizing needed. But, when the footage is unsmooth, with some stabilizing needed (which is generally not completely satisfying with the stabilize behavior), how you can manage tracking other than with automatic tracking is beyond me... (=beyond my current capabilities). I recently had to do some tracking on this video https://www.videvo.net/video/young-boy-playing-piano-in-the-street-2/5804/ and had to use Stabilize first, then Automatic tracking to obtain this wishy-washy result at [1'47 - 2'11] on here again https://youtu.be/0GrZBO8X8fQ where the superimposed standing figure wriggles a bit due to an imperfect tracking (hence, the blended organ keys help a lot...). I tried manual tracking here with no result to speak of since the movement is too random. BTW, the preceding scene [1'21 - 1'46”] is far from perfect in this regard, but in the end manual tracking a la fox-m proved indeed slightly better than automatic tracking and way more simple, so it is manual tracking for this one. As to the opening scene, the time-lapse of the sky (played in variable speed with Kfs) skips some frames (sometimes more than one at a time) and I don't think it shows. I've yet to ascertain that values you enter as Kfs should always be integer numbers (to specify exact frames) since the retiming field reads decimals due to the slowing down of the clip...

OK, so I've tried it. Absent any tracking capabilities in FCPX, I think your plug-in may be of undeniable help for FCPX users at least and I don't even understand why it didn't exist yet. I'm no fan of FCPX but when you think of it, what help do you have there for manual tracking... I'd think of creating a null object (which is what your plug consists in) but I can't remember if FCPX allows for the linking of coordinates (?) as Motion does. Zooming in on the tracked area/target enhances the advantage and helps too.

The help is theoretically the same for Motion users... but they will tend to try automatic tracking first, which may be a mistake (as was my case in this aforementioned scene with the girl in a red dress where manual tracking ended up better). That said, I realize there is a un inevitable limit: the limbo in which some footage leaves you because the flaws are too big to be solved by mere stabilization (maybe several passes though...) and too small to be efficaciously managed and organised by manual tracking. So, no magic bullet.

nb: If the user displaces their keyed footage [from (0,0)] to begin with, it seems they'll have to use the Offset coordinates (as I had to). In reality, Offset is probably inevitable in a keying scenario.

Thank you very much fox. I will try this in FCPX (I only regret you did not make it for Motion).

BTW: I sent you an email a few days ago about a different problem. I hope you received it.