How to Rotate Video by Custom Angle in FFmpeg

This guide demonstrates how to use the rotate filter in FFmpeg to rotate a video by any custom angle. You will learn the core command syntax, how to convert degrees to radians, and how to adjust the output frame size to prevent the edges of your rotated video from being cropped.

The Core Rotation Syntax

FFmpeg’s rotate filter (-vf "rotate=...") expects the rotation angle to be specified in radians rather than degrees.

To rotate a video by a custom angle in degrees, you must convert the degrees to radians using the formula: degrees * (PI / 180). FFmpeg conveniently provides the PI constant to use directly inside the command.

Basic Rotation (with cropping)

To rotate a video clockwise by 45 degrees using the default video dimensions:

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

Note: This basic command keeps the original video width and height. Because the video is rotated within the original boundaries, the corners of the frame will be cropped.

Rotating Without Cropping (Fit to Screen)

To prevent the corners of the video from being cut off, you must dynamically recalculate the output frame size. You can achieve this by setting the output width (ow) and output height (oh) using FFmpeg’s built-in rotw (rotated width) and roth (rotated height) functions.

Rotation with expanded frame

To rotate a video clockwise by 33 degrees and expand the frame to fit the entire rotated image:

ffmpeg -i input.mp4 -vf "rotate=33*(PI/180):ow='rotw(33*(PI/180))':oh='roth(33*(PI/180))'" output.mp4

Rotating Counter-Clockwise

To rotate the video counter-clockwise, simply use a negative angle value. For example, to rotate 15 degrees counter-clockwise:

ffmpeg -i input.mp4 -vf "rotate=-15*(PI/180):ow='rotw(-15*(PI/180))':oh='roth(-15*(PI/180))'" output.mp4

Customizing the Background Color

When you rotate a video and expand the frame, empty triangular areas are created in the corners. By default, FFmpeg fills these areas with black.

You can change this background color using the fillcolor option (or c). For example, to fill the background with red:

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

To make the background completely transparent (requires an output format that supports transparency, like VP9 or ProRes):

ffmpeg -i input.mp4 -vf "rotate=45*(PI/180):ow='rotw(45*(PI/180))':oh='roth(45*(PI/180))':fillcolor=none" output.mp4