Timeline Editing and Assembly
Edit types and track targeting
Timeline assembly rewards precision about edit operations. Three-point editing sets source In and Out plus a sequence In or Out; four-point editing uses both source and sequence ranges and can trigger a fit-to-fill or overwrite depending on settings. Overwrite replaces material on targeted tracks; insert pushes downstream material later and can shift sync. Source patching and track targeting decide where video and audio land. Sync Lock protects tracks during ripple operations, but it only works when enabled on the tracks you want to move; it does not lock a clip from trimming.
Trim tools
Learn the trim family: ripple changes one edit point and shifts all later material; roll moves an edit point between two adjacent clips without changing sequence duration; slip changes a clip’s source in and out while its timeline position and duration stay fixed; slide moves a clip earlier or later while adjusting the neighboring clips. Rate Stretch changes clip speed to fill a gap, often altering audio pitch unless pitch is preserved. The Selection tool versus Track Select Forward and Backward and Razor tool behavior also appears in questions.
Worked example: A 10-second gap must disappear without moving the following interview sound. Use a ripple delete on the gap only if Sync Lock is on for the audio you want to preserve alignment with; if audio is intentionally independent, unlock it or use overwrite. To shorten a clip and leave a hole, do not ripple-trim normally. Rule of thumb: ask whether total sequence duration should change; if yes, ripple; if no, roll or regular trim.