Slice 11 — Video-audio ducking + per-slide audio overrides #12

Parent

#1

What to build

The Planner computes a ducking envelope: music ducks to 20% (with short attack/release ramps) wherever a video slide's own audio plays, restoring after. Per-slide audio overrides in the slice-7 popover: mute video audio / mute music / custom mix levels.

Type: AFK | Stories: 23, 24

User stories covered

• Story 23: background music ducks to ~20% while a video clip's own audio plays
• Story 24: per-slide audio overrides (mute video audio / mute music / mix levels)

Acceptance criteria

• Given a video slide between photo slides, when played, then music audibly ducks during the video and recovers after, with no pops (ramped, not stepped).
• Given "mute video audio" on a slide, when played, then music continues at full level through that slide; given "mute music", the inverse.
• Given a planned timeline, property test: ducking segments in the envelope exactly cover unmuted video-audio spans.

Technical notes

Envelope is Planner output (pure, tested); Composition applies volume curves per remotion-best-practices: audio.

Blocked by

• Blocked by Slice 10 — Folder audio + soundtrack playback #11