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Speed up or slow down parts of clip?

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Sun, 02/10/2013 - 21:26
#1
cyberang3l
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Speed up or slow down parts of clip?

Is this possible?

All of you might have seen video clips running in a specified frame rate and suddenly when something cool happens (a good face punch if a fight for example) suddenly it slows down or speeds up for a certain amount of time and then it's back to normal.

Can I achieve this with kdenlive?

An example video using this technique a lot:
https://www.youtube.com/watch?v=kh29_SERH0Y

Look at 2:50-2:55. The snowboarder comes at a certain speed and when he does the flip the clip slows down and after a couple of seconds is back to normal.

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Mon, 02/11/2013 - 04:17
#2
ttguy
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Re: Speed up or slow down parts of clip?

Yes. An effect called speed in the motion group of effects.

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Tue, 04/09/2013 - 20:45
#3
keupoftea
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Re: Speed up or slow down parts of clip?

I don't think you can achieve this effect with kdenlive because speed effect is not keyframable and it does not recreate the missing frames when you slow down your video (the result will look choppy).

What you're looking for is a flow editor like slowmovideo (linux,MacOS and windows) or twixtor (windows only, non-free in any way).

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Tue, 04/09/2013 - 22:48
#4
ttguy
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Re: Speed up or slow down parts of clip?

@keupoftea - true that speed is not key frameable. But you can just cut your clip at the points you want to have different speeds at and apply different speed effects to the fragments.

And what missing frames do you mean? You expect it to interpolate frames that are not in the original recording? Is there any tool that can do that? Unless you record at a high frame rate you are always going to have a bit a of a choppy effect with slow mo I would have thought.

Here is an example of my use of the speed effect in kdenlive for slow mo http://youtu.be/hiBMWPo088k?t=1m52s

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Wed, 04/10/2013 - 08:00
#5
DiveO
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Re: Speed up or slow down parts of clip?

As ttguy said, you need to cut anyway ... not much of an issue. What the real problem is that the speed effect is extremely buggy. The timeline often does not match the real length so you end up, for instance, with the last real frame repeated for almost a second when you speed up a clip. Also, positioning in kdenlive doey not match what mlt things, then there are corrupted frames, and so on.

But I still have hope that this may get fixed. But at this time, kdenlive's speed effect is like gambling with low chances...

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Wed, 04/10/2013 - 08:47
#6
samoos
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Re: Speed up or slow down parts of clip?

It is possible to do speed ramping in kdenlive... just not with an effect. see attached pictures...
it's slow, it's inflexible, and it's ridiculous, but that's how they would have done it in the old film days!

speedramping01.png speedramping02.png
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Wed, 04/10/2013 - 09:20
#7
normcross
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Re: Speed up or slow down parts of clip?

I never use the speed effect any more, not now we have 'SlowmoVideo'

This is just a silly bit of fun video. It's in low rez but it does show what can be done with SlowmoVideo.
(Oh yes, it can speed up too)

The first part is normal speed:-

https://vimeo.com/57308885

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Wed, 04/10/2013 - 09:34
#8
ttguy
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Re: Speed up or slow down parts of clip?

Divo - I wonder if 0.9.6 will fix your speed issues.
It fixes
issue #1745 Speed effect modifies video size
and
issue #2963 Speed effect makes kdenlive crash

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Wed, 04/10/2013 - 10:44
#9
keupoftea
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Re: Speed up or slow down parts of clip?

As normcross pointed it out, we have now slowmovideo, an equivalent of twixtor. Slowmovideo can interpolate the frames, recreate motion blur and much much more.

I'm not sure but it seems to me that the main developer of slowmovideo has also made a lot of work on color in kdenlive.

Have a look at the vidéos on his website to see the true power of slowmovideo !

http://slowmovideo.granjow.net/index.html

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Wed, 04/10/2013 - 12:34
#10
ttguy
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Re: Speed up or slow down parts of clip?

Wow. So I stand corrected on frame interpolation. That is freaking cool man.

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Thu, 04/11/2013 - 07:16
#11
DiveO
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Re: Speed up or slow down parts of clip?

ttguy, waiting for sunab's repo to get the packages updated. There have been compilation problems lately and sunab seems to be tied up with other things so the repo is currently behind.

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