09 · audio

A BGM track plus four short SFX, each synced to a visual event. The BGM ducks (volume drops) while a SFX is playing and recovers afterwards — driven by ordinary volume keyframes on the audio sequence.

• Multiple type: 'audio' sequences mixed together at init time and at render time
• volume animatable via keyframes — fades, ducks, cuts
• SFX placement via at, the engine handles per-frame mixing
• Visual cues align to audio events; if you scrub the timeline, the audio scrubs too
• Re-uses _assets/bgm.mp3; SFX are tiny ffmpeg-synthesised mp3s in _assets/sfx-*.mp3