Fit
fit
The fit parameter controls how a video is resized when both w and h are specified. With only one dimension, every mode preserves aspect ratio without cropping or padding.
| Value | Behavior | Distorts? | Output size |
|---|---|---|---|
scale (default) | Stretches to exactly w×h | Yes, if aspect differs | Exact |
crop | Center-crops to the target aspect, then scales | No | Exact |
clip | Fits within w×h, preserving aspect | No | ≤ requested |
max | Like clip, but never upscales past the source | No | ≤ requested and ≤ source |
fill | Fits within, then pads to exact w×h with a background | No | Exact |
fillmax | Like fill, but never upscales the foreground | No | Exact |
smart-crop | AI subject-tracking crop to fill | No | Exact |
scale
The default behavior. Stretches the video to exactly the requested dimensions. If the aspect ratio of the request differs from the source, the video is distorted. Use another fit mode to resize without distortion.
crop
Scales the video to fill the target box, then center-crops the excess. The output is exactly w×h with no distortion and no bars.
To steer the crop toward an edge or a specific point in the frame, use the crop gravity parameter (e.g. crop=top) or a focal point with crop=focalpoint and fp-x / fp-y. video-center-crop=true is a legacy alias for fit=crop.
clip
Fits the entire video within the requested box, preserving aspect ratio. No cropping or padding: one axis will be smaller than requested. Use fit=fill to pad to exact dimensions instead.
max
Like clip, but will not upscale a source smaller than the requested box. The output is always ≤ the source resolution.
fill
Fits the entire video within the box (like clip), then fills the leftover border to produce an output that is exactly w×h. The fill defaults to a solid black background; use fill=blur for the popular blurred-background look, fill=image for a branded backdrop image, or fill-color to change the solid color.
fit=fillmax is identical but never upscales the foreground past its source resolution.
smart-crop
Enabling Capability
This parameter can be disabled/enabled in the Advanced Settings of your Source.
All rendering capabilities are enabled by default.
Activates AI subject-tracking crop mode, which automatically detects the focal point of interest in the video and crops to fill the specified w×h dimensions. If a subject moves out of frame, the crop window adjusts to the next most relevant subject.