View Full Version : Breaking space time continuum

12-03-2008, 04:49 PM
First let me say, it's a shame Newtek can't get the audio portion of the clip to work with the control tree video playback speed :(

That said, to make video ping pong, forward and back at a particular portion, of the clip, use the control tree, layer properties, playback speed with key frames.
100 is normal but -100 is reverse.
This is great for doing a "Yo-Yo" effect to a person who fell down.
Also for sports to show the dunk or stretch for a touch down.

Now you need to understand something about SpeedEdit.
If you change the control tree playback speed, it does not lengthen or shorten the clip as the Selected Clips Properties does.
Also the audio will not change when use the control tree playback speed (Newtek make that happen).

This is important to know because if you have a 5 sec clip you want to make go back and forth at certain frames, key framing the playback speed will not change the clips length so by going positive and negative on your key frame values, you will run out of clip time since it stood at it's original length because control tree playback speed does not change the clips length (man I am saying that a lot in this post).

So fear not because all you need do is press the space time continuum button and bam, now you can have it ping pong back and froth as many times as you want.

What your version of SpeedEdit does not have this button?
Ohhhhh.... forgot I modified my version.
You guys need to open the Selected Clip Properties window and change the speed of the clip to extend the clip :)
So if I need a length that is four times the original length to give me the amount of time I need for my "Yo-Yo" effect of the woman who fell catching the bouquet.
But now the clip is playing at 25% :(
So all you need to do is make all forward clip key frames 400 and all reverse key frames -400.
Why, because 400% is normal speed of a clip that has been slowed down to 25% speed.

If I lost anyone, again fear not.
A Learn Alien lesson will be posted one day showing the technique.

Take care,

12-03-2008, 06:51 PM
Interesting method. Yeh, you lost me a couple times but I'll play with it tomorrow to clear things up.
Thanks for sharing!

12-03-2008, 07:25 PM
You see it better when you do it for sure.
But maybe this explains it more.
Say your clip is only 5 sec.s long.
When you use the control tree Playback Speed and you set it to 25, what you did is change the playback to 25% playback speed but the length will still be 5 sec.s long.
What you get is on a chunk of the clip, about 37.5 frames or a little over a sec of the original only.
Not the same as using Selective Clip Properties which if you change the speed to 25%, the clip length changes to 20 sec.s. and plays the whole clip at 25% speed.

So by using the Selective Clip Prop duration in conjunction with the Playback Speed control tree, you can key frame your clip to change it's speed or direction and have the clips length be long enough to achieve the effect you are striving for.
You just need to take into account the speed to compensate your key frame values to playback at normal speed (100%).

The only draw back is SpeedEdit playback speed in control panel, does not affect the audio portion of the clip :(

Hope that helps,

12-04-2008, 08:24 AM
Example using a clip with the length of 4 sec.'s.
Clip Speed = Selected Clip Properties and Playback Speed = Control Tree.

Clip Length Clip Speed Playback Speed
00:04.00 100.00% 100
00:08.00 50.00% 200
00:12.00 33.33% 300
00:16.00 25.00% 400
00:20.00 20.00% 500
00:24.00 16.66% 600
00:28.00 14.29% 700
00:32.00 12.50% 800
00:36.01 11.10% 900
00:40.00 10.00% 1000

So if I changed the clip speed to 20%, the new clip length is 20 sec.'s (original was 4 sec.'s) and to play it back at normal speed, I would have to set control tree playback speed to 500.
This is because it is 5 times slower now at 20%.

Now using key frames with values of 500 and -500 in the spline window, I can make the clip play forward and reverse at normal speed multiple times.
In theory, I can make the original 4 sec clip play forward and reverse five times since the clips duration is now five times longer (in theory but not possible since at lease one frame of the clip is lost for every speed change).

Remember that the audio track does not follow along so uncheck audio so as not to screw with your brain as you play it back.
When you watch video at normal speed but the audio is now five times slower, it messes with you :)

Another important thing to know when doing this;
Say you have a clip where the football player is diving for the touch down.
To isolate the portion of the clip where the player actually crosses the goal line, just creating a cut at this point of the original clip is not enough.
This new isolated clip is not really a clip but just a portion of the original and SpeedEdit is just pointing to it.
You need to render this isolated clip so it is it's own original clip.
After rendering, hold ALT key to drag the new rendered clip over the isolated cut portion to inherit it's space on the time line.
Or you could just delete the cut and add the new rendered clip.

Take care,

12-04-2008, 08:27 AM
If the clip is 4 seconds long, and you set the ControlTree Speed to 50%, then you can manually extend the OutPoint of the clip on the Timeline, stretching it out from 4 seconds to 8 seconds, and you will have the entire clip playing at 50% speed.

The graphic representation of the (now extended) clip on the Timeline might show some diagonal lines which usually indicates the clip is over extended, but this can be ignored.

Hope this helps.

12-04-2008, 08:42 AM
Yes it's the same thing just adding the zebra pattern.
So if you wanted to forward and reverse, you can go 100 to the 4 sec mark and then go -100 for the rest, it will do the same thing.

Either way works but I like using the Selected Clips Properties. Allows for easy calculations of the new key frame playback speed since you can calculate off the new duration time.

But yes that works just fine :)