Trimming

Taking the nearest edit, which side rolls, the keys that move it, typing a trim on the keypad, asymmetric trims for an L-cut, slip and slide, Extend to a mark, and the loop that tells you whether it works.

U takes the nearest edit on the tracks you have on. The two monitors become the two sides of it — the last frame of the outgoing shot and the first frame of the incoming one — and the keys under your hand move the join rather than the playhead.

Escape leaves. Nothing is left half-done: every nudge is already committed, so leaving is just leaving.

Which kind of trim

Two kinds, and the rollers are coloured for them the way Media Composer colours its own:

Ripple is the default. Overwrite is the one to reach for on a cut that has been timed — when the running time is the running time, a ripple is not available and this is. It also asks less of your media than a roll does: a roll pays for the outgoing's tail out of the incoming's handle, so it needs handle on both; an overwrite trim just covers the neighbour up.

Which side moves

U arms a roll, because that is the trim you do most and the only one that cannot change the length of the cut. Switch after you are in; the monitors change to match.

Moving it

J and L on their own play the loop, backwards and forwards, rather than trimming — which is what they do in Media Composer, and the reason an editor's hand stays on those three keys through a whole trim.

Typing it

When you already know the number, type it. In trim mode the numeric keypad trims rather than cueing the monitors: +20 then Enter moves the join twenty frames later, -12 Enter twelve frames earlier. The trim counter shows what you have typed until you press Enter.

+ is always later in the timeline and − always earlier, whichever side the rollers are on. On the B side, +20 shortens the incoming shot, because its first frame moves twenty frames later. That is Media Composer's rule, and it is the same direction . and / move.

A number without a sign is turned down with a message, rather than guessed at: a trim moves from where the cut is, and a plain number is a position. Backspace takes back a digit; Escape throws the entry away and leaves you in trim mode, and a second Escape leaves trim mode as usual.

Trimming on the fly

Turn on Dynamic Trim (Shift-T, or the Timeline menu) and the loop becomes the trim: play it round, press K on the frame the cut should be, and the cut is there. No counting frames, no nudging up to it.

It is off by default, because landing a cut every time somebody pressed stop would be a surprise the first ten times. On, it is the gesture people mean when they say Avid's trim is the best one.

Hearing whether it works

Space plays the loop: two seconds before the cut, two after, round and round, with your changes landing as you make them. J and L drive it too, at shuttle speeds. It is the whole point of being in trim mode rather than dragging something — you are listening to a join, not looking at a number.

Space again, or K, stops.

How much plays is yours to set: Sequence ▸ Sequence Settings… ▸ Trim loop takes seconds, one number for both sides or two for before and after (3, 1 hears three seconds into the cut and one out of it). It is kept for you on this computer and works at any frame rate.

One side on the picture, the other on the sound

This is the trim that makes an L-cut, and it is worth learning because nothing else does it in one move.

Shift-click an edit on another track to add a roller there without losing the ones you have — and the side you get is the side you clicked on: left of the cut is the A side, right of it is the B side, on it is a roll. So picture on the A side and sound on the B side, together, is two clicks.

Then trim as usual. Both rollers move the same way on screen; what they do to their own tracks is opposite, which is the point — the picture reaches further while the sound of the next shot stays where it was, or the other way round. The toolbar says Asymmetric while they are not all on one side.

Several joins at once

Shift-click as many edits as you want, on any tracks, at any points in the cut — including more than one on the same track. Then trim, and every one of them moves by the same amount. Tightening six cuts in a row is one gesture.

The joins stack, which is what you want and worth seeing once: trim three A sides by ten and the first shot is ten longer, the second is ten longer and starts ten later, and the fourth starts thirty later.

Tracks you left without a roller are not padded here either — each rollered track is moving by a different total, so there is no one amount to follow. B/side names the tracks it left.

Three things the rollers do under the mouse, once you are in trim:

That second one is a deliberate departure. Media Composer makes you pass through "both sides" on the way, which costs a click per track and lands you in a state its own designer calls meaningless — editors have been asking for it to stop since 2013. While your rollers are all on one side, flipping one track is one click here.

The tracks you did not put a roller on stay exactly where they are, and B/side says so. There is no amount of filler that keeps a third track in sync with two that are deliberately moving apart, so it does not invent one — and it tells you which tracks it left, rather than letting you find out in a mix review. That is the trade an asymmetric trim is: you are changing the relationship on purpose.

(On an ordinary trim, sync lock behaves the way you expect: tracks without a roller take filler at the edit so they hold, and a trim that would need more filler than there is room for is refused by name.)

Slip and slide: moving the shot, not the cut

Two more trims, and the ones to reach for when the cut is right and the shot is not. Both are on the Timeline menu, and both are modes: turn one on and the keys already under your hand — , . M /, J and L — move the shot instead of the join. Escape leaves.

Slip keeps the window and moves the source under it. The shot starts and ends on the frames it already started and ended on; a different part of it plays. Nothing else on the timeline moves at all, which is what makes it safe on a locked cut — nothing changes length, so sync cannot break. It needs handles at both ends: slipping forward spends the tail's.

Slide keeps the shot and moves it along the timeline. Its source and its length are untouched; the shot before it grows and the one after it shrinks by the same amount, so the cut is the same length and nothing downstream moves. The handles it needs belong to the neighbours, not to the shot you are moving — a shot with no handles of its own slides perfectly well, and a shot between two that are out of material cannot be moved at all.

Select the picture and its sound before you start. Slipping the picture on its own is how a scene goes out of sync with its own dialogue, and B/side will let you, because sometimes that is the edit.

Shift-U is slip and Option-U is slide — beside Trim mode on U, because they are the other two kinds of trim. Remap them like anything else from Help ▸ Keyboard Shortcuts.

Extend: putting the cut where you marked

Sometimes you already know where the cut should be — you are watching, you hear the line land, and you want the join there. Extend does it without entering trim mode at all.

Park where the cut should go, mark one point, and press Shift-E:

The nearest cut on each track you have on rolls to the mark. It is a roll, so the cut does not get longer or shorter and nothing downstream moves — the outgoing shot grows into the incoming one's head, or gives the frames back.

One mark, not both. The mark is what says which direction, so two of them is a question with no answer and B/side says so rather than picking one.

Three things worth knowing, because each of them is a decision you can feel:

• It reaches as far as you marked, however far that is. Mark an OUT two frames before a join and the cut that moves is still the one before your mark, not the nearer one after it — so the outgoing shot runs all the way out to where you marked. That is the point of the command: getting a cut to somewhere several seconds away without touching a trim key. If you wanted the later join pulled back, mark an IN there instead.
• It straightens a split edit. Each track finds its own nearest cut, so picture and sound both land on the mark even if they were staggered. When you want to keep the split, turn off the tracks you do not mean before you press it.
• If the handles run out, it gets as close as it can and tells you how close — naming the track and the frames, like A2 managed 14 of 20. The cut not being quite where you marked is something you need to know straight away, not something to find in a mix review.

What it does to the rest of the cut

A roll moves the join and nothing else: everything downstream stays where it was, and sync is kept without anybody thinking about it.

Trimming one side changes the length of the cut, so everything after it moves. Tracks with sync lock on move together — which is what stops a trim on the picture walking it off its sound.

A trim is an edit like any other: ⌘Z takes it back, it is in What Changed with your name on it, and somebody watching along sees it land.