Trimming

Trimming is adjusting where clips start and end once they're in a sequence, and it is one of Lightworks' great strengths. Rather than dragging clip edges imprecisely, you trim a cut point and watch the result, frame by frame, with picture and sound staying in sync.

How trimming works

To trim, you select a cut point and then lengthen or shorten the clip on one or both sides of it. Hover near a cut until white brackets appear, then click to begin a trim - the edge of the clip curls to show that is unjoined from the cut and ready to move. Drag, or use the play and step keys to find the exact frame, then close the trim to rejoin the cut.

Clicking a cut point trims the clip you clicked. You don't have to set anything up first - pointing at a clip is already a statement of what you want to work on. Clip Link decides whether that means the one clip or the whole group it belongs to, and Alt gives you the opposite for that click (see Selecting and moving material).

You can also trim from a selected segment, and a set of new trim cursors gives clear visual feedback about what each trim will do.

Trimming a clip's start or end

• Trim out adjusts the end of the outgoing clip while the incoming clip's start stays put.
• Trim in adjusts the start of the incoming clip while the outgoing clip's end stays put.

Hover near the end or start of the clip until the brackets appear and drag, or use the keyboard shortcuts below.

Rolling trims (move cut)

A rolling trim (move cut) adjusts both sides of a cut at once: the outgoing clip's end and the incoming clip's start move together, so the cut point shifts without changing the sequence length. Use it to slide a cut earlier or later while keeping everything in time.

Ripple trims

A ripple trim changes a clip's length and moves everything after it to suit, so no gap is left. This is the everyday way to tighten or extend a shot while the rest of the cut ripples along.

Slip and slide

• Slip changes which part of a clip is shown - its in and out points move together - without moving the clip on the timeline or changing its length. The clip stays put; the content inside it shifts.
• Slide moves a clip along the timeline, trimming its neighbours to make room, without changing the clip's own content or length.

Trimming with the keyboard

The keyboard makes trimming fast and exact. Default shortcuts:

The Q-W-E-R row maps to the four sides of the two cuts around the playhead, so your left hand can open any trim without looking down.

You can also trim by numbers - type a frame count on the numeric keypad to trim a precise amount - and preview a trim with custom pre-roll and post-roll before committing.

What is trimmed, and what follows

A trim answers three separate questions, and each has one control:

What is trimmed depends on how you start the trim.

• Click a cut point and you trim that clip, plus the clips it is linked to when Clip Link is on. Track state has no say in a mouse trim - the click has already named its subject.
• Trim from the keyboard, the console or the Trim menu and there is nothing to point at, so track state names the subject: the trim is aimed at the tracks you have enabled with the V1 / A1 tabs in the track headers, exactly as an insert, replace, remove or delete is. Each of those tracks finds its own trim point - the related clip where there is one, otherwise whatever sits under the playhead. Black takes a cut like anything else, so a track cannot be left behind by a ripple, and subtitle and FX tracks trim like any other.

A locked track is never touched by anything, and is never brought along for sync either.

Smart trim decides whether the timeline ripples. With it on, trimming one edge of a clip ripples everything after it. With it off, nothing else moves - the change is absorbed by the black beside the trim. It applies only to one-sided trims: a rolling trim, a slip and a slide all move material without shifting anything downstream, so smart trim has no bearing on them. Toggle it with Ctrl/Cmd+T.

Track Sync decides how far sync is maintained on the tracks that aren't being trimmed - normally the disabled ones. With it on, every one of those tracks is moved too so the sequence doesn't drift out of sync, locked tracks excepted. Those tracks are only ever shifted, by absorbing the change in adjacent black; their content is never trimmed, because they are not what you aimed at. Where a track has no black to give, it is left as it is and the offset is recorded as a track sync error you can then correct. With Track Sync off, only the tracks you enabled move and everything else is deliberately left behind. Track Sync lives with the master track buttons above the track headers.

Each track header carries a slim amber Track Sync strip that lights when that track will be held in sync, so you can see what a trim will do to the rest of the timeline before you make it. It lights only when the trim will actually move the timeline: a slip, a slide, a rolling trim and any trim with smart trim off move nothing downstream, so there is nothing for the other tracks to keep up with. Turn the strips off with Show Track Sync Indicators in Timeline settings.

Because smart trim off means nothing ripples, Track Sync makes no difference to a trim in that state - there is nothing to keep in sync.

Smart trim and Track Sync can both be toggled before and after cuts are opened, so you can pick your cut points first and decide how the trim should behave afterwards. The trim brackets update as you press the buttons. Neither button changes what is being trimmed - the subject you clicked stays the subject.

While a trim is open, clicking a track's V1 / A1 tab adds that track to the trim or takes it out again. Removing the track you opened the trim on closes the trim, since that is the point everything else is measured from.

Trim material indicators show the trim movement live in seconds and frames, and warn you with "no material available" when a clip has run out of footage to trim into.

Trimming one clip on its own

Alt while clicking a cut point inverts Clip Link for that one click, so it always gives you the opposite of however the button is set:

• With Clip Link on, Alt+click trims the clip you clicked and leaves its linked clips alone - the way to take picture away from its sync sound for a single trim.
• With Clip Link off, Alt+click widens the trim to include the linked clips.

Grouped tracks always come along, because a stereo pair or a stereoscopic L/R pair is never split down the middle.

Alt is a mouse modifier. A keyboard or console trim has no clicked clip to work from, so it targets the tracks you have enabled - which is what track state is for.

Trim direction modes

You can choose how dragging maps to the trim:

• Natural - you drag the media.
• Visual - you drag the cut point.

Pick whichever matches how you think about trimming, in Timeline settings.

Trim collisions

By default a trim stops when it meets adjacent media. With trim collisions enabled, a trim can push into neighbouring material, overwriting it - useful when you deliberately want to extend a shot over what's next. Use it knowingly, since it changes adjacent clips.

Trim settings

Two settings in Timeline settings are worth knowing about:

• Click To Unjoin (Trimming), on the Behaviour tab, controls whether clicking a cut point opens a trim. It is on by default. Turn it off if you keep opening trims by accident and would rather trim only by click-and-drag. Deliberate unjoins are always honoured whatever this is set to - the keyboard, the console and the Trim menu all keep working.
• Trim Point Indicators, on the Appearance tab under Trimming, marks the cuts a trim will open. It defaults to Segments And Black, which includes the cuts on black that hold your other tracks in step - so you can see the full extent of a trim before you commit to it. Segments Only leaves the black out, and Off hides them.

Closing a trim

When the trim is right, close it to rejoin the cut: click the cut point, click the Close button under the sequence viewer, or press Tab. The clip rejoins and you're back to normal editing.

Common trimming mistakes

• Running out of material. A clip can only be extended as far as its source media allows. Watch for the "no material available" warning.
• Losing sync. With Track Sync off, only the tracks you enabled move and the rest are left behind. Leave Track Sync on unless you have a reason not to, and watch the amber strips in the track headers to see which tracks are being held in step.
• Trimming the wrong side. Check the yellow brackets show on the side you intend before you drag.
• Forgetting to close the trim. Until you close it, you're still in trim mode. Close the cut to resume normal editing.