Compositions

Compositions are the core containers in After Effects — timelines that hold layers.

Schema

Property	Type	Required	Default	Description
_id	string	no		Reusable composition template id
_extends	string	no		Inherit from a composition _id in the same array
name	string	yes		Composition name
width	int	no	1920	Width in pixels
height	int	no	1080	Height in pixels
duration	number	no	10	Duration in seconds
framerate	number	no	30	Frames per second
pixelAspect	number	no	1	Pixel aspect ratio
color	string	no	000000	Background hex color
folder	string	no		Target project folder
layers	array	no		List of layers
markers	array	no		List of markers
essentialGraphics	array	no		Essential Graphics properties

Basic usage

Minimal composition (uses all defaults):

compositions:
  - name: My Comp

Creates a 1920x1080, 30fps, 10-second composition.

Custom settings

Override defaults as needed:

compositions:
  - name: Instagram Story
    width: 1080
    height: 1920
    duration: 15
    framerate: 30

  - name: 4K Master
    width: 3840
    height: 2160
    framerate: 24
    duration: 120
    color: 1a1a2e

Adding layers

Layers are defined in a layers array:

compositions:
  - name: Title Card
    layers:
      - name: title
        type: text
        text: Chapter One
      - name: background
        type: solid
        color: 000000

See Layers for complete layer documentation.

Layer stack order

Layer order in Compdown syntax maps to the AE stack with the first layer on top. Put background layers later in the list so they render behind foreground layers.

Composition nesting

Reference other compositions using the composition key on a layer:

compositions:
  - name: Lower Third
    width: 1920
    height: 200
    layers:
      - name: bar
        type: solid
        color: FF5500

  - name: Main Comp
    layers:
      - name: lower third
        composition: Lower Third  # Nests the Lower Third composition
        transform:
          position: [960, 980]

Reference behavior

Compositions are created before layers, so forward references are allowed. Use unique composition names to avoid ambiguous references.

Inheritance (_id / _extends)

Use _id to define a reusable base composition and _extends to inherit and override fields.

compositions:
  - _id: sceneBase
    name: Scene-01
    duration: 30
    framerate: 24
    color: ff8000

  - _extends: sceneBase
    name: Scene-02

Rules:

• _extends can only target _id values in the same compositions array.
• Object values are merged deeply.
• Array values are replaced (not concatenated).
• Duplicate _id, missing _extends targets, and circular inheritance fail validation.

See Inheritance for full inheritance behavior and additional examples.

Placing in folders

Organize compositions in project folders:

folders:
  - name: Comps
  - name: Precomps
    parent: Comps

compositions:
  - name: Lower Third
    folder: Precomps

  - name: Main Comp
    folder: Comps

Markers

Add composition markers for navigation and scripting:

compositions:
  - name: Main Comp
    markers:
      - time: 0
        comment: Intro
      - time: 5
        comment: Main Content
      - time: 10
        comment: Outro

See Markers for full marker documentation.

Essential Graphics

Expose properties to the Essential Graphics Panel:

compositions:
  - name: Template
    layers:
      - name: title
        type: text
        text: Edit Me
    essentialGraphics:
      - title.text
      - title.transform.position

See Essential Graphics for full documentation.