Fill Image

Sets a custom background image to fill the border when fit=fill or fit=fillmax is used with fill=image.

fill-image accepts an absolute URL or a path relative to the source video. The image is fetched through the same proxy as mark and is cover-scaled to fill the entire canvas without distorting — the center of the image is always visible. Use fill-darken to dim the backdrop so the foreground video stands out.

If the image fails to fetch or is not a supported format, the render falls back silently to fill-color (default black) rather than erroring.

For a Base64-encoded image URL, use fill-image64 instead.

fill-image only takes effect with fill=image. It is ignored for other fill values and other fit modes.

To animate the background with a slow pan or zoom, see fill-image-motion (Ken Burns effect).

Animating the background

Use fill-image-motion to add a slow pan or zoom (Ken Burns effect) to the background image. The motion applies only to the fill canvas — the foreground video is unaffected. This is particularly effective for audiograms, where the audio source has no inherent video motion.