Arranging Effects in Time

Effects in a composition live in time: each effect occupies its own strip on the Timeline — with a start, an end, and a duration. While the time cursor is inside the strip, the effect is rendered on the fixtures; outside it, the effect simply doesn't exist. By arranging strips along the scale and layering them on top of each other, individual effects are combined into a finished animation.

This article is about working with strips: how to move an effect, shorten it, place it exactly on the frame you need, and what happens at the boundaries of a composition. For the window itself and its panels, see Timeline; for adding effects, see Adding an Effect to a Composition.

What the Effect Strip Shows

Open a composition with a double-click in the Compositions window — its contents will appear in the Timeline window.

On the left are listed the layouts and the effects nested in them; on the right, on the time scale, are the strips of these effects. To see the effects of a layout, expand it with the arrow to the left of its name — a collapsed layout shows no strips.

An effect's strip is a light gray rectangle on the layout's dark track. Its left edge is the moment the effect begins, its right edge is when it ends, and its width is its duration at the current scale of the timeline. A strip under the mouse cursor lightens slightly; a selected one lightens noticeably and is outlined with a light border.

A few important points:

an effect only works inside its own strip and switches on and off abruptly: there is no fade-in or fade-out on the strip itself — smoothness is achieved with opacity keyframes, see Keyframes and Effect Parameters;
time inside an effect is counted from the left edge of the strip, so its whole animation travels together with the strip: move the effect 10 seconds later, and its motion also starts 10 seconds later;
a new effect added from the Effects window occupies the entire composition — from zero to its end. It is then shortened and moved manually;
the checkbox to the left of the effect's name turns it off entirely, regardless of the strip's position: with the checkbox unchecked, the effect plays nowhere and is not included in the export;
under the strip are tracks only for parameters that have keyframe mode enabled — as a flat list, without groups. Opacity keys lie on the effect's strip itself.

Selecting Strips

Click a strip with the left mouse button — the effect will be selected, and its parameters will open in the Properties window.

Ctrl + click — add an effect to the selection. Shift + click works the same way, but Shift is used for snapping while dragging, so Ctrl is more convenient for selection.
You cannot deselect a single strip by clicking it again: to leave only it selected, click it without Ctrl.
Clicking an empty area of the timeline deselects all effects.
The right mouse button does not change the selection: the context menu works with whatever is currently selected — select the strip with the left button first.
Selected strips move and are deleted together, as a single group.

Moving an Effect in Time

Select the strip (or several strips).
Press the left mouse button on the strip, in its middle, and, without releasing it, drag the mouse right or left. Dragging doesn't start immediately, but after a shift of a few pixels — a short click won't move the strip.
Release the button at the desired place. The image in the Mapping field and in the 3D View is recalculated immediately.

What happens:

the effect always lands on a frame boundary — you cannot land "between frames";
the strip's duration does not change, only its position does;
the effect does not go beyond the composition's bounds: at the zero mark and at the end of the composition, the strip stops at the boundary and goes no further;
several selected strips move together, keeping the distances between them. But at the composition's boundaries, each strip stops on its own, and the relative arrangement can shift — when moving a group, it's better not to push it right up against the edge;
the layout does not change when dragging along the scale. To move an effect to a different layout, drag it by its name row on the left side of the window — see Перемещение эффектов между лейаутами.

Changing Duration

Move the cursor to the left or right edge of the strip: right at the edge, in a strip about a dozen pixels wide, the cursor changes to a left or right arrow. Drag the edge — the strip will stretch or shrink, while its other edge stays in place.

Edge	What changes
Right	The moment the effect ends. It does not go past the end of the composition
Left	The moment the effect begins. The effect's keyframes stay in their place in time — only the reference point shifts, and the animation is "trimmed" from the front

Limitations:

an effect cannot be made shorter than one frame — the strip will hit its minimum length;
only edges of regular effects can be dragged. An imported video's strip cannot be dragged by its edges: its length is calculated automatically from the file's duration and the Loop Count value in the Properties window;
stretching an effect to the right does not stretch its animation: the keyframes stay where they were, and after the last key the values simply stop changing.

The audio track is moved and trimmed with the same techniques, but by its own rules: its right edge does not go past the end of the audio file, and its left edge trims the beginning of the sound itself.

Snapping Strips to Each Other

During normal dragging, a strip moves freely. To join effects end to end, without a gap or overlap, hold Shift — this enables snapping. While the key is held, the edges of the dragged strip stick:

to the starts and ends of all other strips visible on the timeline — including in other layouts and to audio tracks;
to the start of the composition;
to the current position of the time cursor.

The point of snapping is shown by a vertical light-blue line, and the strip it snapped to is outlined in red. Snapping works both when moving a whole strip and when dragging either of its edges. It triggers when a few pixels remain to the target on screen: the larger the scale, the more precisely you need to bring the strip. Release Shift — the strip moves freely again.

Two more things: strips of a collapsed layout do not participate in snapping, and the end of the composition is not a snap point — a strip stops there on its own anyway. When you drag several strips at once, only the outer edges of the group stick — the start of the earliest and the end of the latest.

A time-saving trick: place the time cursor at the desired moment — it's easier to aim at than an empty scale — and pull the edges of the strips to it with Shift held.

Landing Exactly on the Right Moment

There are no numeric start/end fields for a strip in version 3.3 — the Set time item in the strip's context menu remains inactive. When you need to land not "by eye" but exactly at a given moment, proceed as follows:

Place the time cursor exactly where the effect should begin: type the time into the current time field on the timeline's playback panel, or step to the needed frame with Ctrl + → and Ctrl + ←.
Zoom in on the scale with the mouse wheel so individual frames on it are distinguishable.
Pull the strip's edge to the cursor with Shift held — the edge will snap exactly to it.

It's convenient to check the result with a frame-by-frame step: stand on the frame before the effect's start and step forward — the effect should appear exactly on the next frame.

Besides Set time, the strip's context menu has Copy and Delete. Deletion works both from there and with the Delete and Backspace keys. But copying a strip — neither with this item nor with Ctrl+C and Ctrl+V — is not possible in version 3.3: a copy of an effect is made with the Duplicate command in the list on the left.

Time Cursor

The orange vertical line on the timeline is the time cursor: it shows which moment of the composition you're currently seeing in the Mapping field and in the 3D View.

Click the top ruler with the time scale — the cursor will jump to that point. Without releasing the button, you can drag it along the scale and "flip through" the animation manually, even moving the mouse outside the window; playback pauses while doing this.
The cursor always lands exactly on a frame — just like the edges of strips.
Space — play and pause, Home — go to the start of the composition, End — go to the end; the scale scrolls there as well.
Ctrl + → and Ctrl + ← — step one frame forward and back, Ctrl + Shift + → and Ctrl + Shift + ← — ten frames at once. Stepping with keys also pauses playback.

The current time and frame number are shown on the timeline's playback panel, next to the composition's duration.

Scale and Scrolling

Strips a fraction of a second long can't be made out on a minute-long scale, so the scale changes on the fly:

mouse wheel over the scale — zoom time in and out. The scale changes relative to the pointer, so aim it at the part you want to examine;
dragging with the wheel held (or the right button) — scrolling: horizontally it scrolls through time, vertically — through the list of layouts and effects. A short right-click still opens the context menu;
the preview bar at the very bottom of the window: the middle slider moves the visible time segment as a whole, the side ones set its length.

The scale does not zoom in closer than about half a second across the whole window width, and does not go beyond the composition's bounds. The scale's zoom is for viewing only: it does not affect the effects themselves or the export.

Overlapping Effects in Time

Within one layout, strips can overlap in time as much as needed. At a moment when several effects are playing at once, they are composited top to bottom: an effect that is higher in the layout's list is drawn over the ones below it, according to its blend mode and opacity. The order is changed by dragging the effect's row on the left side of the window, see Режимы смешивания.

Hence two common techniques:

image change — strips go end to end: one ends, the next begins. Easiest to set up with Shift snapping;
smooth transition — strips overlap, and the opacity of the upper effect is animated with keyframes in the overlap zone.

To repeat an effect later in the composition without configuring it again, right-click the effect's row on the left side of the window and choose Duplicate: a copy will appear in the same layout next to the original, at the same point in time, already selected — all that's left is to drag it. The neighboring Clone item sends a copy of the effect to another composition in the project.

Composition Boundaries

The length of the scale is the composition's duration. It's set by clicking the underlined duration value on the playback panel, or by right-clicking the composition in the Compositions window → Set Duration. See Настройки композиций.

Worth remembering:

effects cannot go past the end of the composition: when dragged or stretched, they stop at it;
shortening the duration of a finished composition is risky. Effects that cross the new boundary are cut off at it, and those that end up entirely past it are removed from the composition. They won't come back on their own, so it's better to set the duration before arranging effects;
in a composition with Infinite enabled, time continues past the end of the scale. At that point, only effects stretched all the way to the composition's end keep playing: the rest have already finished by then;
the cue file gets exactly what plays within the composition's duration — see Exporting Compositions.

If an Effect Plays at the Wrong Time

Check in order:

whether the time cursor is inside the effect's strip — most often the effect simply hasn't started yet or has already ended;
whether the checkbox next to the effect's name is enabled and whether it has zero opacity set;
whether the effect is covered by another one — one lying above it in this layout, or an effect in a layout positioned higher on the timeline;
whether it's the right layout: the strip may have ended up in a neighboring layout, and the effect is playing on other fixtures — see Перемещение эффектов между лейаутами;
whether the starts of the strips coincide, if several effects are supposed to start at the same time: pull their edges to each other with Shift held, otherwise a discrepancy of a frame or two will stay invisible on the scale but will show in the animation.

Keep in mind: shifting and trimming strips in time is not recorded in the undo history. Ctrl+Z will undo adding or deleting an effect, but will not return a strip to its previous place on the scale — position is restored by dragging.

Keyboard Shortcuts

Action	Keys
Play / pause	Space
Time cursor to start / end	Home / End
Step one frame forward / back	Ctrl + → / Ctrl + ←
Step 10 frames forward / back	Ctrl + Shift + → / Ctrl + Shift + ←
Snapping while dragging strips	hold Shift
Add an effect to the selection	Ctrl + click (or Shift + click)
Delete selected effects	Delete or Backspace