Aftereffects we do a lot of effects on videos obviously.
And one of the very useful effect is changing time.
It means playing the movie faster or slower or mixing fast and slow and making some time in the video.
That's very fast or very slow.
And so on you know mixing all this time games we want to learn how to use the frames per second and
understand what these frames per second for the video.
And also for the composition after effects it's all the same concept and the same understanding how
to use the frames per second.
I have created a composition here this composition.
If I come to composition setting you know do this very well I hope I have used 12 80 by 720 25 frames
per second and the duration of the composition is 25 seconds.
There is a layer here which is if you click on the video here you will see that we do is A.D. by 720
It is 12 seconds and 12 frames.
And also it is 25 frames per second.
Now if you have a video that you want to put in a composition you should always try to match the frames
per second of the video and the frames per second of your composition to do that.
You don't have to come and create a compere a new camp and put the parameters that are there.
The easiest way to create it is to click on the video derogate and put it on the.
I can hear that represents the camps and letting go.
So immediately ill create a new composition for you where it places the video player and also it uses
the same parameters or the same settings as the video itself.
Fine.
I will delete this one we don't need it just to show you.
This is the best way if you have a single video within your composition.
So this is the video I'm going to play it is a simple video is around 12 seconds like we said and we
are going to decide OK I want to make that video faster.
The first option I have and there are similar options.
The first option I have is to change the frames per second for the video the original footage that I
have.
What is frames per second.
Lets look at it.
If I stretch to the maximum I notice that have zero one frame 0 2 frames 0 3 0 4 or 5 video is usually
shot through a camera and this camera settings could be 25 frames per second.
It means every second there will be 25 frames and if you put them all together and play them through
one second it will make a certain movement.
Of course I'm sure you know all already that you can shoot also.
Up to 60 frames per second in a normal camera.
So for here I have 25 frames for every second.
Now if I make it 50 frames per second what will happen is if I take this same movie and make it 50 frames
per second of course it will look like it is a bit faster.
Lets try to change the speed of our footage.
You select your footage here and come to the into Prete footage.
Just the I can hear it click on it and it will open a dialog box that it is about to beat ceiling.
Thats the name of the video of course.
So you have main option and color management.
We care about the frame rate only.
So this is 25 frames per second.
What happens if I make it 50 frames per second you know exactly that had the duration of your video
is cut by have already doubled the frame rates.
Remember it was 12.
Now it is or it is six seconds 50 frames per second.
If I click OK or press ENTER NOW THE VIDEO IS NO MORE 12 seconds is only six.
If I play it here you are.
It looks much faster and its you know quite funny is jumping fine.
So what did aftereffects do.
Let's zoom in and you notice now it has deleted or it has merged Actually it has deleted certain frames
and compressed them maybe to make it look like it's faster so I don't have any more 25 frames per second.
I have 50 frames per second.
And now the video is shortened in time.
Now that's very nice.
Let's go back to our we select our selling video.
We click on into each footage and we bring it back to let's see 12.
Now if I put 12 frames per second the duration of the video is going to become 26.
Notice I'm changing the footage here.
I'm not changing the movie on my storage device.
I'm enjoying it just yet.
So I have 12 frames per second and now it's 26 seconds.
Press Enter now the video is quite long.
It's even longer than the compositionally can star come here and adjust the time you make it for example
40 seconds and the period.
So now it's quite ok.
I can see it here if I play my footage now you got this it's quite slow of course it's almost half the
time even more.
So where did these extra frames come from.
That's a good question to ask.
OK.
I had 25 frames.
Now I have 12 per second.
Where do they come from.
Let's zoom in and see exactly what the after effects that this is my first frame.
Nothing is happening.
Another one nothing is happening.
And so on until the number five.
So four five frames it was still the same frame.
So I said if X had duplicated these frames one after the other then if I come to six nothing happens
and so on until the next frame it's almost at 8 here nine a bit more and nothing happens so actually
actually these are what after effects has done is to duplicate the frames are deflected the shots if
you want.
So now for the first five frames is the same one.
Now you get the movement here or you get the animation.
That is not very smooth.
You know it's like jumping a bit.
So now let's look exactly what happened here.
I come to this frame zoom in and look at it carefully.
That is one frame.
OK it has moved from here to here.
Then it moves in nothing.
And here and here and here you notice how the movement is jumping.
The I can't see that because now I can discern between these frames there is time enough for me to see
that it is jumping even on normal speed.
You can see how I see jumpgate fact how to remedy that.
The first option you have is enable frame blending.
It means after are going to blend two frames together to create your missing frame.
That's one way to do it to do that.
First of all you enable frame blending here.
This is for the preview to be able to preview and then you put the frame blending on this small.
I can here click just once when you click once it start blending the frames.
Now notice what's happening before I have this position of the mast.
And then one more I have like two mass here.
There is kind of shadow.
OK.
So let's come back here.
This is the first one.
This is the same one than this one and this one.
So after if they had taken this frame and this frame and blend them to have the flame in between.
So now you have like a ghost here or you know it kind of shadow we call that many ghosts.
So let's look at the movies sometimes some movies videos can be you know rendered very nicely here and
look very small.
But now in this one we see the ghost a bit.
It's not much if you're just uploading this to Facebook and so on is OK but if you're doing a professional
job there will be a really big problem.
Let's go back what other options we have.
If I click once again now this is a frame blending.
If I click once again I will be mixing boxes.
It means that let's zoom in
aftereffect is going to try to guess what is the next position of that box.
So if you come here than here over here now there is no more boasting.
What happens is after effects.
Looked at this frame and looked at the frame after for example this frame and the frame after that and
they decide OK this is where the pixels are.
And this is where the pixel will be.
So in between I'm going to invent a new you know position for the pixels.
So actually not using frames but it's using movement of boxes.
And that's why is pixel motion you are motioning or you are moving the pixels.
This is a very important concept.
The difference between blending frames creating an in-between frame that is the blend of the one that's
before and the one that's after.
And the big set motion where after effects try to guess or try to understand the frame before or the
position of the as before and the position of the pixels after and to create one in between.
To give you a smooth motion.
Now this is very important when you become a real pro you you're not is that many of these techniques
are not very conducive when you're doing commercial high quality work.
But for now it's OK.
You can start learning from that.
And then we go to maybe in this course.
I hope so to go to more advanced Plug-In that you will help you're doing you know more the better merging
and better slow motion.
Now let's play our movie put it back at 100 percent and I think this is OK.
We have stretched the time.
It has become a very slow and we have used books in motion here to be able to have its most movement.
Now there are few things you have to look at.
We have changed the footage.
So if I come here and create a new composition with the same footage.
Of course the layer here is going to use this footage which is the modified footage here.
So by changing the footage by changing the interpretation of the footage you are exactly changing the
footage in your whole project not only in the composition but sometimes you don't want to do this.
Or delete this one.
And what you want to do is just to change the layer speed or you know working only on this they are
not playing with the footage.
We see that in the next lecture.