Keyframes and curves

The model

A keyframe is a time and a value. The time is measured from the start of the clip, not from the start of the timeline, and that one decision is what makes an animation part of the clip rather than part of the sequence: move the shot, and its animation goes with it. Split it, and each half keeps the keys that fall inside it. Copy it, and the copy is animated too.

Scalars

A number: opacity, a blur radius, a rotation, a volume. The overwhelming majority of keyframes in any project.

Colours

Three channels and an alpha, keyed together under one swatch with one diamond. The curve editor plots them one channel at a time.

Points

An x and a y, keyed together, with the bezier handles that shape the trajectory between them — a position, a focus point, the centre of a lens flare.

Paths

A whole shape. It has no number to plot, so the curve editor falls back to a timing view for it and the shape itself is edited on the canvas.

Setting one

1. 01

   Park the playhead where the value should be what it is

   Keyframe times are relative to the clip, not to the timeline, so the playhead has to be over the clip you are animating.

2. 02

   Set the control

   Drag the label to scrub it, or click the field and type. Either way the whole gesture is one undo step rather than one per pointer move.

3. 03

   Press the diamond

   That is the first key. If the property is already animated you can skip this: moving the playhead and changing the value sets a key on its own.

4. 04

   Move the playhead and change it again

   The second key. There is now an animation between the two.

5. 05

   Shape it

   The tangent button beside the property opens the curve editor on it. Pick an easing from the shelf, or drag the two handles on a key for a shape the shelf doesn't have.

The gutter

Every animatable row in the rack carries the same two controls: a diamond that adds or removes a key at the playhead, and a tangent button that opens the curve editor on that property. Grouped properties — a position is an x and a y — share one gutter, so the diamond keys the whole group and the curve editor lists the other channel beside the one it opened on.

The curve editor

The Curves pane plots one property over the clip's own duration: x is clip-relative seconds, y is the value in the units its control uses. Keys drag in both axes here — this is the one view where the value is editable by dragging — and the segment leaving a selected key takes its shape from the easing shelf or from its two handles.

• A property with several channels gets a switcher and is plotted one channel at a time. Editing one writes the whole value back with that channel replaced, so dragging a colour's red leaves its blue and its alpha alone.
• A path has no channels and no axis it could be plotted against, so it falls back to keys on a ladder with the easing between them still shaped the usual way. The timing is the part of a shape morph worth editing on a curve.

Easing

Eight shapes on the shelf, and a ninth state — custom — which is what a key becomes once you drag one of its handles. Hold is worth naming separately: it does not interpolate at all, so the value stays put and then jumps, which is how you step a counter or cut a mask from one shape to another.

Where it goes, on the canvas

Position is the one property whose animation is not a number. A clip that moves has a path, and no amount of easing on an x curve and a y curve can bend one: two curves make each axis a function of time on its own, and the line traced between two of their keys is straight in space whatever shape either one has. Easing changes how fast you cross a path. It never changes where the path goes.

So position keyframes carry handles that live in space, and the curve they shape is drawn on the preview over the frame it happens in — which is the only place a spatial control can honestly be edited.

Drag a key

Moves where the path passes through that moment. Hold shift to align it to the middle of the frame, its edges, or another key. Double-click to remove it.

Drag a handle

Bends the segment. The opposite handle turns with it, which is what makes the key a smooth pass rather than a corner; hold ⌥ to move one alone.

The key under the playhead

Has no dot of its own to drag — the transform box is already its handle, and moving the clip there writes that very keyframe.

A dashed segment

HOLD easing. The clip is at one key and then at the next, so nothing travels the line between them.

Keys on the timeline

The curve editor answers "what shape is this motion". What it cannot show is an animation against the edit— where the keys sit relative to the cut, the neighbouring shot, the beat they were placed on. Twirling a track open does that: one row per animated property, laid out on the timeline's own ruler.

Drag a key

Moves it in time, and only in time. A row 32 pixels tall trying to be a value axis as well is a control where every horizontal drag is also a vertical one nobody meant.

Drag across the rows

Box-selects every key the box covers, across rows and across clips — ⇧ or ⌘ to add to what you already had. Dragging any one of them then carries the whole set by the same amount, so the shape of the animation survives being moved, and Delete takes all of them.

Double-click a row

Adds a key at that moment. Double-click a key to remove it — or a key inside a selection to remove the selection.

The strip on the clip

One diamond per moment, carrying everything keyed there. The right summary at a glance, and the wrong handle when two properties share an instant — which is what the rows are for.

Animating an effect on and off

The eye at the left of every rack row keyframes like everything else, so an effect can come on part-way through a clip and go off again. On the video side that is a switch. On the audio side it is a crossfade between the processed path and the dry one, because tearing down a reverb graph mid-clip would put a click on the switch and drop whatever was decaying.

Motion blur

A camera pointed at something moving records a smear, because its shutter is open for part of the frame rather than for an instant of it. The aperture switch in a track header turns that on for that lane: anything on it whose position, size, rotation or skew is animated is drawn several times across each frame's exposure and averaged. A clip you have simply placed somewhere is not moving, so it looks the same either way — the blur comes from the keyframes.

Per lane, and nowhere else, because that is how a timeline already groups things that should behave alike: the shot blurs, the lower third over it stays crisp, and neither of them needs a switch of its own.

Angle

How much of a frame the shutter is open for. 180° is the film convention — half the frame, and what most footage you have seen was shot at. 360° never closes it.

Phase

Where the exposure sits against the frame. The default of half the angle, negative, straddles it: the smear runs either side of where the clip actually is. Zero opens the shutter at the frame instead, so the smear trails behind.

Samples

A ceiling, not a count. How many times a clip is drawn follows how far it travels, so a slow drift costs two draws and a whip pan costs the ceiling. Clips that aren't moving cost nothing at all.

Angle, phase and samples are in project settings, because they describe the camera the whole edit was shot with — how long the shutter is open, not what it is pointed at.

The blur comes from the animation, not from the footage: a clip smears because you moved it. Motion inside the frames themselves is already in them, and the Shutter Blur effect blends recent frames if you want more of it.

Shortcuts

K

Toggle keyframe snapping

← / →

Nudge the playhead one frame — the grid keys land on

⌘/Ctrl + Z

Undo, including a whole drag as one step

What each animatable property actually is depends on the clip and its rack: see Effects & transitions, Text & captions and Audio.