Audio for Video: Beds, Ducking & Beat-Synced Cuts

8 min read

Pick the right music bed, duck it under narration like a pro, and sync your cuts to the beat — the mixing craft that makes videos feel expensive.

Watch any video that feels "expensive" and mute it. Suddenly it is just... footage. The polish you sensed was mostly audio: a music bed matched to the energy, narration sitting clearly on top, and cuts landing on the beat. This finale lesson turns everything you built in this path — songs, instrumentals, voiceovers — into a finished soundtrack.

Music Beds: Supporting Actor, Not Lead

A music bed has one job: set the emotional temperature without stealing attention. Three rules. Go instrumental whenever there is narration — sung lyrics and spoken words fight for the same brain. Match energy to content, not to your taste: a calm product demo dies under epic trailer drums. Favor steady dynamics — a bed with huge builds and drops keeps yanking the viewer's attention away from your message. Generate beds with tags like steady dynamics, background music, no drastic changes.

Ducking: Make Room for the Voice

Ducking means lowering the music whenever someone speaks. The industry-standard move: drop the bed by 12 to 18 dB under narration, then ease it back up in the gaps. Editors automate this with sidechain compression — the voice track literally pushes the music down — but even manual keyframes work. Two refinements: duck *before* the first word (a 0.5-second pre-roll sounds intentional), and if you split your track into stems, duck only the drums and other stems while leaving the bass — the mix keeps its warmth.

Beat-Synced Cuts: The Math Is Easy

Cuts that land on the downbeat feel choreographed; cuts that land between beats feel sloppy. The arithmetic: one beat = 60 divided by BPM, in seconds, and a 4-beat bar is four times that. Know your track's BPM (you chose it in the style prompt, remember?) and place cuts on bar boundaries:

At 120 BPM, cutting every 2 seconds puts every single cut on a bar line — which is why editors love 120. Save the biggest visual moment for a musical hit, and if the track's chorus lands at 0:45 but your reveal is at 0:52, move the reveal, not the music.

instrumental, warm corporate pop, 120 BPM, clean electric guitar plucks, soft claps, bright airy synth pads, optimistic mood, steady dynamics, background music

Related glossary terms: BPM (Beats Per Minute), Sound Design, Stem, B-Roll

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