3. Name and reference a clip

Your three-image sequence publishes correctly, but it exists only as values immediately consumed by concat. In this chapter you will package those statements as one clip, give it an identity, and reference it later.

Continue editing learning.clipasm from From one image to a sequence.

1. Replace concat with clip

Replace the four executable statements with:

clip {
    image("assets/morning.png", 1500ms, contain)
    image("assets/meadow.png", 1500ms, contain)
    image("assets/evening.png", 1500ms, contain)
}

A clip collects the Video values left by its body and concatenates them in order. The body therefore does not need its own concat.

2. Validate the clip

Validate this version:

clipasm validate learning.clipasm

Expect E_ENTRYPOINT_OUTPUT_COUNT again. This time the diagnostic says that zero Videos remain, not three. The clip form removes its temporary result from the outer stack, so merely creating a clip does not publish it.

3. Give the clip a name

Add as pictures after the closing brace:

clip {
    image("assets/morning.png", 1500ms, contain)
    image("assets/meadow.png", 1500ms, contain)
    image("assets/evening.png", 1500ms, contain)
} as pictures

as pictures preserves the composed Video under an immutable graph name. It still does not place a Video on the outer stack.

4. Reference the named value

Add a reference after the clip:

clip {
    image("assets/morning.png", 1500ms, contain)
    image("assets/meadow.png", 1500ms, contain)
    image("assets/evening.png", 1500ms, contain)
} as pictures

$pictures

$pictures places an occurrence of the named Video at that point in the program. It does not move or change the underlying value.

5. Validate the reference

Validate:

clipasm validate learning.clipasm

The file again leaves one 108-frame Video ready to publish.

You used clip to make one composition and as to name it. You used $pictures to place it on the stack where needed.

Next, transform one scene.