Transform

Scale, crop, trim, adjust speed, and apply geometric effects to video.

Quick example

import { ffmpeg } from "ffmpeg-kit";

await ffmpeg.transform()
  .input("video.mp4")
  .scale({ width: 1920, height: 1080 })
  .trimStart("00:00:10")
  .duration(60)
  .output("clip.mp4")
  .execute();

API

.input(path)

Input video file path. Required.

.scale(options)

Parameter	Type	Default	Description
width	number	—	Target width in pixels
height	number	—	Target height in pixels

Omit one dimension for proportional scaling.

.fit(mode)

How to handle aspect ratio mismatch when both width and height are specified.

Value	Description
"contain"	Fit within dimensions, letterbox/pillarbox as needed
"cover"	Fill dimensions, crop edges
"fill"	Stretch to exact dimensions (distorts)
"crop"	Center-crop to exact dimensions

.trimStart(t)

Start time for the output clip.

Parameter	Type	Description
t	number | string	Seconds or timecode "HH:MM:SS"

.trimEnd(t)

End time for the output clip.

.duration(seconds)

Duration of the output clip in seconds. Cannot be combined with .trimEnd().

.fps(rate)

Output frame rate.

.speed(factor)

Playback speed multiplier. 2 = double speed, 0.5 = half speed.

.rotate(degrees)

Value	Description
90	Rotate 90° clockwise
180	Rotate 180°
270	Rotate 270° clockwise (90° counter-clockwise)

.flipH() / .flipV()

Horizontal or vertical flip.

.crop(options)

Parameter	Type	Description
width	number	Crop width in pixels
height	number	Crop height in pixels
x	number	Left offset (default: center)
y	number	Top offset (default: center)

.output(path)

Output file path. Required.

Examples

Scale and crop for social media

// Instagram square crop from 16:9 video
await ffmpeg.transform()
  .input("landscape.mp4")
  .scale({ width: 1080, height: 1080 })
  .fit("cover")
  .output("square.mp4")
  .execute();

Speed up and flip

await ffmpeg.transform()
  .input("slow.mp4")
  .speed(2)
  .flipH()
  .output("fast-flipped.mp4")
  .execute();

Trim a segment

await ffmpeg.transform()
  .input("long-video.mp4")
  .trimStart("00:01:00")
  .trimEnd("00:02:30")
  .output("segment.mp4")
  .execute();

Result type

interface TransformResult {
  outputPath: string;
  width: number;
  height: number;
  duration: number;
  size: number;
  probeResult: ProbeResult;
}

Related

• Extract — extract frames
• Export — re-encode with quality presets
• Pipeline — chain multiple transforms