L-Cut — effect skill for cuts & pacing

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Shot A's sound keeps playing after the picture cuts to B. Carries a line or a mood across the edit.

What it does

Picture changes to B (a reaction, B-roll, the next place) while A's voice or music continues underneath. On a timeline the audio forms an L.

When: Reactions during dialogue, narration over B-roll, letting a moment breathe as you leave a scene.

Watch out: Carrying speech too long over unrelated images makes the speaker feel disembodied.

Timing: Audio tail 0.5–2 s past the cut; fade the tail out

Also called: L cut, audio overlap, sound carry-over, split edit

In FFmpeg

Picture cuts at 3 s; A's audio runs to 4 s; B's audio joins at 4 s in sync (source 1 s):

ffmpeg -i a.mp4 -i b.mp4 -filter_complex \
"[0:v]trim=0:3,setpts=PTS-STARTPTS[va];[1:v]trim=0:3,setpts=PTS-STARTPTS[vb];\
 [va][vb]concat=n=2:v=1:a=0[v];\
 [0:a]atrim=0:4,asetpts=PTS-STARTPTS,afade=t=out:st=3.4:d=0.6[aa];\
 [1:a]atrim=1:3,asetpts=PTS-STARTPTS,afade=t=in:d=0.3,adelay=4000:all=1[ab];\
 [aa][ab]amix=inputs=2:normalize=0:duration=longest[a]" -map "[v]" -map "[a]" out.mp4

In HyperFrames

Keep A's sound as its own <audio> clip longer than A's muted picture; use data-fade-out for the tail:

<video id="a" src="a.mp4" data-start="0" data-duration="3" muted data-track-index="0"></video>
<audio id="a-snd" src="a.mp4" data-start="0" data-duration="4" data-fade-out="0.6" data-track-index="2"></audio>
<video id="b" src="b.mp4" data-start="3" data-duration="3" data-track-index="1" data-has-audio="true"></video>

In Remotion

<Sequence durationInFrames={90}><Video src={a} muted /></Sequence>
<Sequence durationInFrames={120}><Audio src={a} /></Sequence>  {/* audio runs 30 frames longer */}
<Sequence from={90}><Video src={b} /></Sequence>

Use useCurrentFrame() + interpolate() for the tail fade (the volume callback is no longer recommended).

In CapCut

Separate audio from clip A, trim A's video shorter, then extend A's audio clip under B and fade it out.

Where this comes from

Use when

Not for

Install

Example output

https://s3.varg.ai/how-to/previews/f1d2f569de6f/take-l-cut.mp4 — cut between two shots, with the timeline strip of the edit. Footage: Charge (2022), Blender Studio | studio.blender.org, CC BY 4.0; Tears of Steel (2012), (CC) Blender Foundation | mango.blender.org, CC BY 3.0. (credit: Rendered by varg · Charge (2022) + Tears of Steel (2012))

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