Three-point editing

Dragging whole files from the bin works for rough assembly, but most editing is more precise than that: this part of a shot, there in the sequence. Three-point editing is the classic way to do it. You mark a range in the Source monitor, mark where it goes in the sequence, and press one key to cut it in — either pushing the rest of the edit along (Insert) or recording over what’s there (Overwrite).

It’s called “three-point” because three marks are enough: pick any three of the source In, source Out, sequence In, and sequence Out, and Sprocket works out the fourth. If you’ve used another professional editor, the keys and rules will feel familiar: , and . for Insert and Overwrite, source patching to choose destination tracks, and track targeting and sync lock to control what moves.

The three-point workflow

Here’s the whole loop, end to end:

Open a clip in the Source monitor. Double-click it in the Media bin. The monitor switches to its Source tab and shows the whole, untrimmed file. (Selecting a clip that’s already on the timeline loads its file too; click the Source tab to see it.)
Mark the part you want. Play or scrub to the start and set a source In, then to the end and set a source Out (see Mark the source range).
Say where it goes. Park the Program playhead where the clip should start — or set sequence marks on the timeline for more control (see Choose where the edit lands).
Check the patching. The V1 / A1 chips at the far left of the track headers show which tracks the video and audio will land on (see Patch the destination tracks).
Press , to Insert or . to Overwrite. The marked range is cut into the sequence as a new clip — linked video and audio for a file that has both.

Afterwards the sequence marks are cleared and the playhead parks at the end of the new clip, ready for the next edit. The source marks stay, so you can cut the same range in again elsewhere. The whole edit is one undo step (Ctrl+Z).

Insert and Overwrite are also on the Clip menu (Insert Edit and Overwrite Edit) and on the bar under the Source picture. They’re available whenever the Source monitor holds media, and the keys work whichever monitor you’re looking at.

Mark the source range

Source marks work just like the sequence marks described in Marks and markers, but they belong to the media file rather than the sequence:

I / O — set the source In / Out at the Source playhead
Shift+I / Shift+O — jump to the source In / Out
Alt+I / Alt+O — clear the source In / Out; Ctrl+Shift+X clears both
Ctrl+Shift+Space — play just the source range, In to Out

The keys act on the Source media when the monitor is the active pane with the Source tab showing. Double-clicking a bin item makes it active for you; otherwise click the Source picture (or press Shift+3). With the timeline active they mark the sequence instead. The Mark In and Mark Out buttons on the bar under the Source picture always mark the source, whichever pane is active.

The same bar reads out the marked range — In, Out, and Dur (duration) — and the marks are drawn on the scrubber under the picture. The Source monitor always shows the whole file; the marks only say which part an edit will use.

Source marks are saved per media item with the project. Open another file and come back, and its marks are still there. A bin tile whose media has marks shows a small badge with the marked length, such as [0:03]. Setting and clearing source marks is undoable, like any other edit.

Tip: You don’t have to mark both ends. With no source Out, the edit runs to the end of the file; with no source In, it starts at the beginning. With no source marks at all, the whole file is used.

Choose where the edit lands

Where the new clip goes is decided by the sequence marks on the timeline ruler:

No sequence marks — the edit starts at the Program playhead. This is the quickest way: park the playhead and press , or ..
A sequence In — the edit starts there.
A sequence In and Out — the edit fills exactly that range.
Only a sequence Out — the edit is backtimed: it’s placed so it ends at the Out.

Set sequence marks with I and O while the timeline is the active pane — see Marks and markers.

Patch the destination tracks

A narrow column at the far left of the track headers holds the source indicators: a V1 chip on the lane the source video will land on, and an A1 chip on the lane for its audio. They only appear while the Source monitor holds media with that stream — a video with no sound shows no A1 chip, and an audio file shows no V1 chip.

Move a chip by clicking the column on another lane of the same kind. The chip jumps to that lane.
Turn a stream off by clicking the chip itself. It stays on its lane but dims, and that stream isn’t edited in — for example, un-patch A1 to cut in only the picture. Click it again to turn it back on.

By default the video is patched to the bottom video track and the audio to the first audio track. Patching is saved with the sequence, and each change is one undo step. If you delete the track a chip is on, it falls back to the default track; undoing the delete puts it back.

Insert and Overwrite refuse to run, with a message in the status bar, if nothing is patched or a patched track is locked.

Insert or Overwrite

Both edits cut the same range to the same place. The difference is what happens to what’s already there:

Overwrite (.) records over whatever the patched tracks hold in that range, trimming or removing it. Nothing else moves, so your sequence stays the same length. Use it to drop a cutaway over existing footage.
Insert (,) splits the existing clips at the edit point and pushes everything after it to the right to make room, so the sequence gets longer. Every patched track moves, plus every other track with sync lock on, so the rest of the edit stays in sync. Sequence markers after the edit point move with it.

How the marks combine

You rarely need all four marks. This is how Sprocket resolves each combination — the standard three-point editing rules:

Source marks	Sequence marks	What happens
In and/or Out (or none)	none	The source range goes in at the playhead.
In and/or Out (or none)	In	The source range goes in at the sequence In.
In and/or Out (or none)	Out only	The source range is backtimed to end at the sequence Out.
In (or none)	In and Out	The edit fills the sequence range, starting from the source In.
Out only	In and Out	The edit fills the sequence range, backtimed so it ends at the source Out.
In and Out	In and Out	A four-point edit: the source In and the sequence range win, and the source Out is ignored. The status bar says so.

A missing source In means the start of the file; a missing source Out means its end. If the source doesn’t have enough footage to fill the range the marks ask for, the edit is shortened to the footage available, and the status bar notes it.

Tip: Want a four-point edit that uses both source marks exactly? That means changing the clip’s speed to fit — use Fit to Fill.

Fit to Fill

Fit to Fill squeezes or stretches the source range so it exactly fills the sequence In–Out. Set a sequence In and Out, mark the source (or leave it unmarked to use the whole file), then press Shift+F11 or choose Clip ▸ Fit to Fill.

The clip lands as an Overwrite on the patched tracks, played at a constant speed of source length ÷ sequence range. A 4-second source range filling a 2-second gap plays at 200%. The status bar reports the speed, for example “retimed to 200%”. The speed is an ordinary clip speed, so you can change it later in Clip ▸ Speed / Duration (see Changing a clip’s speed).

Fit to Fill needs both sequence marks. Without them it does nothing and says so in the status bar.
It refuses a fit that would need a speed outside Sprocket’s 1%–10000% range.
A still image has no fixed length, so it simply fills the range at normal speed.

Like Insert and Overwrite, it clears the sequence marks and is one undo step. The shortcut is Shift+F11.

Drag from the Source monitor

You can also drag the marked range straight onto the timeline:

Drag the Source picture onto a lane to bring in both video and audio.
Drag the Drag Video Only or Drag Audio Only handle on the bar under the picture (the film and music-note icons) to bring in just that stream.

The drop overwrites at the drop point, which snaps like any other drag. Hold Ctrl (Cmd on macOS) as you drop to insert instead. While you drag, a ghost shows the range that will be overwritten; with Ctrl held, arrows show what will be pushed right.

The stream you drag lands on the lane under the pointer. The other stream goes to its patched track. Unlike , and ., a drag brings the companion stream along even when its chip is un-patched. A drag uses the source marks but not the sequence marks, and leaves them in place.

Dragging a file from the bin works the same way — see Putting media on the timeline.

Track targeting, sync lock, and lock

Each track header has three editing-state toggles on its bottom row:

a targeting chip labelled with the track’s short name (V1, A2…),
a lock (padlock), and
a sync lock.

If the header column is narrow, sync lock is hidden first, then lock. All three are always on the track’s right-click menu too, as Target Track, Sync Lock, and Lock Track, along with Target All Tracks and Target No Tracks.

New tracks start targeted and sync-locked, and unlocked. Each toggle is one undo step and is saved with the project.

Targeting

Targeted tracks are the ones sequence commands act on:

Lift and Extract remove the marked range only from targeted tracks (see Lift and Extract).
Mark Clip (X) marks the clip under the playhead on the topmost targeted video track (or the first targeted audio track).
Paste lands on the first targeted track of each kind.
Up / Down stop at edit points on targeted tracks (see Jump between edit points).

Targeting is separate from patching: patching decides where a source edit lands, and targeting decides what the sequence commands touch.

Sync lock

Sync lock decides which tracks shift when an edit ripples — Insert, Extract, and dropping with Ctrl held. A sync-locked track shifts along even when it isn’t targeted or patched, so the music and titles under a scene stay lined up with the picture. Turn sync lock off on a track you want to stay put, such as a music bed that should keep playing under an insert.

Lock

A locked track is protected from changes: its clips can’t be selected, moved, trimmed, cut, dropped onto, or edited by an AI assistant. The lane is drawn with a hatch pattern so you can see it’s locked. If a clip on another track is linked to a clip on a locked track, the locked partner stays put.

A locked track never shifts, either. If an Insert or Extract would need to push a locked track, that track is left as it is and the status bar notes that it may now be out of sync.

Jump between edit points

To move the Program playhead from cut to cut:

Up — jump to the previous edit point (a clip’s start or end)
Down — jump to the next edit point

These stop only at edit points on targeted tracks. Hold Shift (Shift+Up / Shift+Down) to consider every track. They’re a quick way to park the playhead exactly on a cut before an Insert.

Marks and markers — sequence In and Out marks, Lift and Extract, and markers.
Preview and monitors — the Program and Source monitors.
Putting media on the timeline — dragging from the bin, with overwrite and Ctrl-drop insert.
Editing on the timeline — trimming, moving, and the track headers.