Music bed and sound effects

Music choice matters more than music processing: a track whose energy does not match the cut cannot be fixed with EQ. In a production this layer is on by default, unless the brief rules it out or the music IS the content; a small change adds no sound unasked.

Workflow

1. Choose the track. The user's own first. Otherwise stock (fetchStockMedia mediaType:"audio", audioPurpose:"music", one or two concrete words) or original music (generateMedia kind music with a musical brief: mood, instruments, tempo, structure; Studio). If the edit has a turn in it, pick music with a turn in it and align them.
2. Lay the bed in one command: musicBed adds the music across the picture, sets a bed level with fades and ducks it under the voice where it is actually speaking. Use autoDuck for music that is already placed. fetchStockMedia places a stock track bare, with no fades, ducking or looping, and its note reports the URL: musicBed with that URL as src and the same clipId replaces it with the finished bed.
3. Levels. volume and duckTo are linear gains, and duckTo is the ABSOLUTE volume the music drops to under speech, not a dip below the bed. musicBed sets the bed at 0.35 and ducks to the autoDuck default 0.2, a dip of only about 5 dB (20 x log10(0.2 / 0.35)). For a dip of about 10 dB under a 0.35 bed, follow musicBed with autoDuck (clipIds the music clip, voiceClipIds the speech) with duckTo about 0.11 (0.35 x 10^(-10/20)); in general duckTo = bed x 10^(-dB/20). How far the music then sits under the voice depends on how loud each source is, so judge it with the audio review, not the numbers. Exports are loudness-normalised to -14 LUFS (true peak -1.5 dBTP) by default; that moves the whole mix, never the balance between voice and music.
4. Fades. Every music track fades out rather than stopping dead; an abrupt cut to silence reads as unfinished.
5. Sound effects. Short hits from stock (audioPurpose:"sound_effect"), ONE per moment: a riser leads INTO the cut, a whoosh starts about 0.1 s before it so its peak lands on it, an impact lands ON it, a pop lands as a graphic appears. Hits go on graphics and major transitions, not every cut. Give the first a clipId and reuse the URL in its note with addClip type:"audio", so a piece has one family of sounds. Level with setAudio volume (start about 0.3 to 0.5), under the voice, and judge by listening.
6. Silence is a tool. Dropping the music for one beat before a reveal beats any transition effect.
7. Listen to the result with agentWorkspace action review mode audio before claiming the mix works.

Gotchas