Add or replace a soundtrack

Use set_audio to attach standalone Audio to a Video or replace Audio the Video already carries.

Before you start

Create an initialized project. Add these media files:

assets/scene.mp4
assets/soundtrack.wav

The Video and Audio may have different durations. The resulting Video keeps the Video timeline. set_audio trims longer Audio and pads shorter Audio to match the Video duration.

1. Create the source file

Create soundtrack.clipasm:

clipasm 1

config {
    video {
        width = 1920
        height = 1080
        fps = 30
    }
    output = "generated/with-soundtrack.mp4"
}

video("assets/scene.mp4", contain)
audio("assets/soundtrack.wav")
set_audio

The first two calls leave one Video and one Audio value. set_audio binds each input by its exact type. It replaces the Video’s Audio and leaves one Video.

2. Validate the structure

clipasm validate soundtrack.clipasm

Validation checks the source without opening either media file. File-backed durations may remain deferred until rendering.

3. Render the video

clipasm render soundtrack.clipasm

4. Check the soundtrack

Open generated/with-soundtrack.mp4. Confirm that its picture comes from scene.mp4 and its sound comes from soundtrack.wav.

See set_audio for its exact contract and Stack binding for mixed Video and Audio inputs.