Original subtitles

In the previous video I showed you how we could adjust the

timing of a clip using the Read node.

In this video we're going to start looking through the

nodes available to us in the Time menu,

and see how we can use them to create the same results.

There are many reasons why we might want to use these nodes

instead of using the controls inside the Read node.

Personally, I prefer to separate important operations into specific nodes,

so each step is obvious to anyone looking at the script.

There are also some extra controls in these nodes that

can produce slightly better results.

Also, these nodes can be applied at any point in a script,

so it's possible to apply these retimes to whole sections of

your work whilst keeping the script live.

This project has the same frame range as in the previous video, 1001 to 1055.

The first trick I'm going to show you is how to burn in the

frame numbers into your source footage.

This will help us see the effects of our retiming.

In the previous video I had baked the frame numbers into

the frames that we were working with.

Obviously, we don't want that burn-in in our final image.

In this video we're working with the same footage, but without the burn-in.

We can create that burn-in nondestructively with a Nuke,

so we can switch it off once we are happy with our retime.

We will create the burn-in with a Text node.

In the Text node message field add value frame in square brackets.

The brackets tell the Text node to evaluate what is inside as a TCL expression.

The word value tells Nuke to look up a value,

and the word frame tells Nuke to look up the frame number of the current frame,

and return it to the expression.

The result is that the Text node prints the frame number over the image.

This frame number is based on the Nuke timeline,

not the input frame number of the image,

so if we have already adjusted the timing if the sequence inside the Read node,

this number isn't going to match the source frames.

We can use a different expression if we want to read the

original frame number from the metadata of the original image

with metadata input/frame inside brackets.

If I display both of these together we can see how the two relate to each other.

We're going to be doing all of our retiming outside of the Read node,

so I'm going to delete the second line,

and display the value that relates to the timeline.

By placing this Text node before any retiming we are baking in

the original frame number of the sequence.

When we view this after the retime we can see where our

original frames are ending up on the timeline.

This can help us sanity check our work and troubleshoot any unexpected results.

So now we can recreate our time offsets from the previous video,

but with separate nodes.

The first node we can look at is TimeOffset.

This is a very simply node that does exactly what the name implies,

and just offsets the frames of the source a regular amount.

Oddly,

this works in the opposite direction to the offset option in the Read node.

In the Read node we used -781 to get frame 220 to line

up with frame 1001 of our timeline.

In the TimeOffset node we add 781.

There is also a reverse option,

which will reverse the frame range of the clip before applying the offset.

The TimeClip node replicates the controls that are inside the Read node,

but with a few extra features.

There is a reverse option if you want to play your clip backwards,

and there are also fade in and fade out options if you feel

the need to fade you clip in and out.

We can use this in the same way that we used the Read

node controls in the first video.

Let's set the frame range we want to work with to 222 to 274.

Then let's choose start at, and set that to 1001.

Now we have 220 starting at 1001 of our timeline.

The next node to look at is the Retime node.

This node can be used to move a clip along the timeline by changing the

input frame range relative to the output frame range,

and it also has speed controls.

These two sets of controls work together.

Changing one will affect the other,

and you can use them in different combinations.

Let's start by using the input frame range to define the

first frame that we want from our footage.

If we enable the first box in the input range and enter 220

this will now be the first frame of our clip.

If we set the timeline range to input you can see that it now starts at 220.

Notice how the number in the grayed out output range changes to match.

We can now use the output range to remap the first frame of

our clip to the first frame of our timeline.

If we enable the first frame of our output range,

and set that to 1001,

and reset the timeline to global you can see that we have map 220 of

the footage to the first frame of our timeline.

The rest of the frames are all now relative to that,

so that we have 274 as the last frame of our shot.

This is effectively giving us the same result as using a TimeOffset node,

but I find this way of working much easier.

Say, for example, I have a shot with an explosion,

and I want to add a fireball element to it.

If I know the fireball starts on frame 25 of its clip,

but the explosion starts at frame 1010 of my shot it's real easy to just set the

input first frame to 25 and the output first frame to 1010.

I don't have to do the math to work out what offset I need to apply.

We could have done the same thing by using the last frames

instead of the first frames by setting the input last frame to

274 and the output last frame to 1055.

We can use the speed slider to change the speed of the footage too.

Numbers larger than one will speed the clip up.

Numbers smaller than one will slow it down.

So if we run the first frame of the clip as 220,

but then to play the clip twice as fast,

we can set the input first frame to 220,

the output first frame to 1001, and then set the speed to 2.

Notice how the output last frame changes when we speed the clip up.

This is because the speed of the clip is going to affect the length of the clip.

The length of the input clip, the frame it starts on,

and the speed at which it's played will define the frame that it ends on.

This works with any combination.

If we define where the last frame should be,

but uncheck the first frame,

and change the speed you'll see that the frame that the clip starts on changes.

Let's reset the speed to one.

Now let's define the beginning and the end of the clip in the input range,

220 to 274, so the clip is now only 55 frames long.

You can see that the output last frame displays 1005 automatically.

Now, watch what happens when we enable the fourth variable in the frame range.

The speed settings is disabled.

This is because we are now manually defining all four

variables in the input and output,

and the speed the clip must play is defined by that relationship.

Right now the difference between the first and last frame of

the input is the same as the difference between the first and

the last frame of the output.

Both have a frame range of 55, a 1 to 1 relationship,

so the clip will play back at its normal speed,

but if we were to change one of these, so the 1 to 1 relationship is broken,

you'll see that the speed has to change to compensate.

Let's change the last frame of the output to 1027.

This halves the output frame range to the nearest whole frame,

so now there are twice as many input frames as there are output frames,

so the speed has to double, so that the whole clip fits into the new range.

If we change the last frame to 1110 we now have twice as

many frames in the output as the input,

so the clip is effectively being stretched in time or slowed down.

The same thing happens if we change the input rather than the output.

If we leave the output as it was originally,

but change the last frame of the input to 329 we now have twice

as many frames coming in as we do going out,

so we have to play the clip twice as fast to make that work.

If we've defined the input range to match the project range,

but then speed the clip up by two you can see that we are

running out of frames half way through our shot.

This is because by default the Retime node holds the first and

last frame of the range if we go beyond them.

We can use these before and after settings to choose what

Nuke displays outside the input range.

Hold will show a freeze frame, black will just show empty black frames,

loop will loop the selected frame range over and over,

bounce will ping pong the footage backwards and forwards over and over,

but the most useful option, by far, is the continue setting.

This will keep playing the rest of the frames as normal

outside the selected frame range,

so we could use the input and output first frames to line up a particular

piece of action that might be in the middle of the clip,

and the rest will continue playing before and after that point.

The filter settings define how Nuke interpolates

between frames when changing the speed.

The default setting, box, will do some basic frame blending,

whereas the other two just show whole frames,

either rounding up or down to the nearest.

The shutter setting adjusts how the box filter blends the frames together.

We will look at frame interpolation more in another video.

The next node is the FrameRange node.

This simply allows you to set the frame range of a clip,

but doesn't shift it along the timeline.

Unlike the read or TimeClip nodes,

it doesn't actually trim the frames off outside of this range,

but it does change how Nuke displays the clip.

These nodes all appear in the Dope Sheet.

The Retime node isn't editable here.

It only displays the result.

If you don't already have the nodes open in the properties pane you

can click this button to show all Read nodes and TimeClip nodes that

are in your script in the Dope Sheet.

To display the TimeOffset,

Retime or FrameRange nodes you must open them in the Properties pane.