Audio Mixing

Use mixAudio to generate audio samples in JavaScript and mux them into the video. This example synthesizes the first phrase of Ode to Joy and visualizes the waveform in real time.

Notes

• mixAudio callback runs once per frame and returns a Float32Array of audio samples. The library muxes them into the video's audio track. No microphone permissions needed.
• Phase accumulators (stored in a ref) keep the oscillator phases continuous across frames. Two oscillators run per note: the fundamental and a sub-octave at 30% amplitude for warmth.
• Per-sample envelope ramps amplitude smoothly over 3 frames at each note boundary, creating clear note separation without clicks.
• Spectrum-style bars show a gaussian peak centered at the current note's frequency. As the melody plays, the peak slides across the bars. Exponential smoothing creates a trailing glow effect.