Import and call a source program

Use a source program when an operation needs a reusable callable interface. This guide creates a polish program and imports it under a local name. You will then render its result without completing the ordered learning chapters.

Before you start

Create a project so the starter image is available. Then enter the project:

clipasm init imported-video
cd imported-video

Create a programs directory inside the project.

1. Define the program

Create programs/polish.clipasm:

clipasm 1

input video: Video
param by: Number = 6%

zoom_in($video, $by)

The file accepts one Video and an optional zoom amount. Its final Video returns to the caller.

2. Create the composition

Create composition.clipasm in the project root:

clipasm 1

config {
    video {
        width = 320
        height = 180
        fps = 24
    }
    output = "generated/imported-program.mp4"
}

import "programs/polish.clipasm" as polish

image("assets/morning.png", 2s, contain)
polish(10%)

The import path is relative to composition.clipasm. polish is a local call name. The call consumes the Video on the stack. It also overrides the program’s default by parameter.

3. Validate the package

clipasm validate composition.clipasm

Validation checks both source files and reports 48 frames without opening the PNG.

4. Render the result

clipasm render composition.clipasm

5. Check the result

Open generated/imported-program.mp4. Confirm that the morning image zooms for two seconds.

See Imports for exact path, alias, isolation, and cycle rules.