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Export renders every frame with the same renderer the CanvasKit player uses, so a video is pixel-identical to full-fidelity playback. --format is required; the output extension isn’t read.

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Formats

Animated WebP stores a run of identical frames once, and an animation that never changes becomes a still image. It is larger than WebM for long or large animations; for those, WebM or a player on the page is the better fit. An SVG is one file animated with CSS, with text drawn as outlines, and it takes none of the options below. It matches every frame exactly, so if a document has something SVG can’t draw, such as a shader effect or a camera, nothing is written and the command lists those nodes. For a single still, use render-frame instead.

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Quality

--tier picks an encoder preset: draft, review, final or master. --quality 0..100 sets the encoder quality directly (default 85). --supersample 2 renders at twice the output size and downsamples, which sharpens thin strokes and small text at the cost of four times the pixels. --alpha preserve keeps transparency in the formats that support it; --alpha flatten composites onto --flatten-color. Frames are transparent wherever nothing is drawn, so a document without a full-canvas background rect exports on black in MP4 and on nothing in MOV. Draw the background.

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Size and range

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Speed

Export cost is per layer, not per second. A flat document renders quickly on the CPU. Every node with opacity below 1, every isolated group, every drop shadow and every effect adds an offscreen pass per frame, and glass, refraction and custom shaders are evaluated per pixel. Progress with an estimate prints to stderr. Exports render on your GPU when that’s faster, in a Chrome, Edge, Brave or Chromium started headless; on effect-heavy documents that is orders of magnitude faster. Without one of those browsers or a hardware GPU, frames render on the CPU. --backend gpu or --backend cpu forces either. GPU and CPU rasterisation aren’t bit-identical, so a GPU export matches the preview rather than a CPU export. --parallelism <n> sets the worker threads for CPU rendering.

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What an export contains

  • The timeline as authored. Interaction bindings never run during export. See Interactivity for what that means for how you author.
  • A progress sheet. hero.mp4.preview.png with the first twelve frames is written beside the output. It’s a convenience, not a deliverable; --progress-preview <file> moves it and --no-progress skips it.
  • A verified file. The result is decoded after encoding to confirm it plays. --no-verify skips that.

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Options reference

Every flag is listed on the export reference page.