Seamless loop problem

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  11 November 2012
Seamless loop problem

I've been trying to generate a sequence that is seamless and I can't figure out why it's not working.

It's running at 30 frames per second and it's two seconds long.

The obvious first question is did you account for frame 0 and finish on frame 59, which I have.

I've also checked each end frame in photoshop to see if they work in sequence, they do.

I've also double checked the sequence runs smoothly at the join by putting it in a 4 second comp in aftereffects. It's fine in the middle but still jumps at the end!

I've run out of ideas, any help would be much appreciated
 
  11 November 2012
Hi, we'd need to see the file or the 4 sec video to help you out. My guess is whatever the animation is (camera obejct etc), the keyframe tangents don't match, so speeds won't be the same.

cheers
brasc
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  11 November 2012
Thanks Brasco,

The movement was generated with a motion clip, but the blending was set to linear throughout
so that shouldn't be a problem. I've also explored all the other settings for blending and none of it made any difference.

Sorry I'm new to this site and was unsure if I could post the sequence, it's a 3MB quicktime, I thought that may be unacceptably big?
 
  11 November 2012
Okay so I've sorted a link so you can see what I mean...

Cheers,

Rob

http://www.cdp2.co.uk/cdpweb/Ants%202%20seconds.mov
 
  11 November 2012
I just tried putting it four times after each other in AE and I can't see any jumps.

In what program do you see the jump, in the Cinema scene itself?
Then I'd guess Cinema does a small recalculation for each run.

Try PLA bake it (and disable any expressions if any).

Cheers
Lennart
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  11 November 2012
Thanks Lennart,

Yeah I've done the same thats why I'm confused.

I duplicated the loop in AE and there was no jump within the sequence, but there is at the end when it loops over. It's only a slight jump but it is there.

I'll look into the PLA bake thing, but to be honest I think it's a problem with how it's viewed or maybe a frame rate issue.
 
  11 November 2012
I've not really studied the clip but just to say - if the animation is looping correctly then the first and last frames should be identical, then it's just a matter of removing that last frame from the movie (or rendering one frame less from Cinema).

Cheers,
Brian
 
  11 November 2012
If it jumps at end to start in AE, it is a playback issue.
I know that in earlier version of AE the very last frame
was not cached ("green") when doing a preview.
I then had to jump to the last frame to get it cached.
I bite me several times when I wanted to check a loop.
I don't see this issue in later versions, AE5.5/6

As it does loop butted together, likely there is nothing
wrong with the actual file.

Cheers
Lennart
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  11 November 2012
Oh, and yes, check that your footage is interpreted correctly.
So you're not playing a 30fps file in a 29.xx comp.

Cheers
Lennart
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  11 November 2012
Thanks for the input guys,

Quote: I've not really studied the clip but just to say - if the animation is looping correctly then the first and last frames should be identical,


Is that right? I was working on the assumption that the last frame was the one BEFORE the first of the of the sequence. Surely if it was the same as the first in the sequence then you would have two frames the same next to each other, or is that a schoolboy error?
 
  11 November 2012
Thanks Lennart,

I think you may be on to something with AE not caching. I'm using AE 5 and when I scroll to the last frame I am getting a green marker at the end!

Is this just a problem when you preview in AE? If so thats not the problem because this is jumping as a quicktime render.

Yeah I've checked the frame rate I am on 30fps.

Thanks,

Rob
 
  11 November 2012
No, I animate cycles all the time (walking characters and that kind of thing) and I always make sure the last frame is identical to the first one but I don't render that last one.

Say for example the cycle is 24 frames long, starting on frame 1, then frame 25 should be the same as frame 1 but I just render from frame 1 to 24. If you render the last frame too then yes, you'll have a hitch in the motion as there will be two frames that are the same, but it's the simplest way to make sure the motion will match cleanly IMO and is a very standard workflow, at least for character animation.

Regards,
Brian

Last edited by Horganovski : 11 November 2012 at 05:42 PM.
 
  11 November 2012
Originally Posted by Bob-T: Is this just a problem when you preview in AE? If so thats not the problem because this is jumping as a quicktime render.

Rob

You cannot safely check a loop in QT without editing its properties,
there is a setting in QT Player to allow some sort of cacheing/hi speed or
whatever it called.
Actually , the Cinema PictureViewer is my preferred tool for checking
files as it caches all perfectly and then plays realtime given enough RAM

Cheers
Lennart
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MSA | OSX | xfiles ...Cinema4D Tools
 
  11 November 2012
Thanks for the input Lennart and Brian, I've certainly learnt something new from you guys.

I'll implement your recommendations asap, unfortunately I'm working on some other stuff right now (pesky real work) but I'll let you know how it goes.

Cheers,

Rob.
 
  11 November 2012
linear mode in keyframes
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