How to Rotate Video by Arbitrary Angle in FFmpeg

Rotating a video by non-standard angles—such as 45, 33, or 120 degrees—cannot be done with simple transpose filters in FFmpeg. Instead, you must use the powerful rotate video filter, which processes rotations using radians. This guide provides a direct, step-by-step tutorial on how to apply arbitrary rotations, prevent cropped corners by automatically resizing the output window, and customize the background fill color.

The Basic Rotation Command

To rotate a video, you must pass the angle to the rotate filter in radians. The formula to convert degrees to radians is degrees * PI / 180. FFmpeg allows you to use mathematical expressions directly in the command.

To rotate a video clockwise by 45 degrees, use the following command:

ffmpeg -i input.mp4 -vf "rotate=45*PI/180" output.mp4

Note: In this basic command, the output video dimensions remain the same as the input video, which means the corners of your rotated video will be clipped.

Rotating Without Clipping (Auto-Sizing)

To prevent the corners of the video from being cut off, you must dynamically recalculate the output width (ow) and height (oh) of the canvas. FFmpeg provides built-in functions rotw(a) and roth(a) to calculate the required bounding box size for a given angle a.

Use this command to rotate the video 45 degrees and automatically expand the canvas size so the entire video remains visible:

ffmpeg -i input.mp4 -vf "rotate=45*PI/180:ow='rotw(45*PI/180)':oh='roth(45*PI/180)'" output.mp4

Changing the Background Fill Color

When you rotate a video by an arbitrary angle, empty black areas will appear around the rotated frame. You can customize the color of this empty space using the fillcolor option (either by name or hex code).

To set the background color to blue, run:

ffmpeg -i input.mp4 -vf "rotate=45*PI/180:ow='rotw(45*PI/180)':oh='roth(45*PI/180)':fillcolor=blue" output.mp4

To use a hex color code (e.g., #FFFFFF for white), format it like this:

ffmpeg -i input.mp4 -vf "rotate=45*PI/180:ow='rotw(45*PI/180)':oh='roth(45*PI/180)':fillcolor=0xFFFFFF" output.mp4

Rotating Counter-Clockwise

To rotate the video counter-clockwise, simply add a minus sign before the angle value. For example, to rotate 45 degrees counter-clockwise:

ffmpeg -i input.mp4 -vf "rotate=-45*PI/180:ow='rotw(-45*PI/180)':oh='roth(-45*PI/180)'" output.mp4