FFmpeg: How To Crop Videos, With Examples

This article explains how to crop videos using FFmpeg (with examples) from the command line. It's especially useful for batch cropping multiple videos, but some (me included) might also prefer this over a fully fledged video editor for doing some video cropping. The article also includes screenshots that show exactly what's being cropped.

To exemplify applying the FFmpeg crop filter I'm using this 500x300 image, in which each square has a size of 100x100 pixels:

For each example command, the image is cropped using the actual FFmpeg crop command from that example, so you can see exactly what happens when using it. This is possible because the same commands can also be used to crop.

To be able to use these commands, you'll need to have FFmpeg installed on your system. FFmpeg is a free and open-source project consisting of various libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the FFmpeg command line program, which can be used for transcoding, basic editing, video scaling, and post-production effects.

FFmpeg crop filter usage

Let's start with the basics. To crop a portion of a video using FFmpeg, the command looks like this:

ffmpeg -i input.mp4 -filter:v "crop=w:h:x:y" output.mp4

What this all means:

• -i input.mp4 specifies the input video (input.mp4 being the input / original video in this case)
• -filter:v (can be abbreviated to -vf) specifies we're using a video filter
• "crop=W:H:X:Y" means we're using the "crop" video filter, with 4 values:
• w the width of the output video (so the width of the cropped region), which defaults to the input video width (input video width = iw, which is the same as in_w); out_w may also be used instead of w
• h the height of the output video (the height of the cropped region), which defaults to the input video height (input video height = ih, with in_h being another notation for the same thing); out_h may also be used instead of h
• x the horizontal position from where to begin cropping, starting from the left (with the absolute left margin being 0)
• y the vertical position from where to begin cropping, starting from the top of the video (the absolute top being 0)
• output.mp4 is the new, cropped video file

A few notes:

• The filter will automatically center the crop if x and y are omitted, so x defaults to (iw-w)/2, and y to (ih-h)/2
• There is also an optional keep_aspect option that you can set to 1 to force the output display aspect ratio to be the same of the input (example usage: "crop=100:100:0:0:keep_aspect=1"). This won't work with images, that's why you don't see a separate example with screenshot here
• FFmpeg gets the original input video width (iw) and height (ih) values automatically, so you can perform mathematical operations using those values (e.g. iw/2 for half the input video width, or ih-100 to subtract 100 pixels from the input video height).

This may sound a bit complicated, but you'll see in the examples that's not the case so much (but of course, it depends on what you want to achieve).

You can preview (play) the video cropping without waiting for its re-encoding by playing it with ffplay (useful for quickly seeing if the crop region is correct), like this:

ffplay -filter:v "crop=w:h:x:y" input.mp4

This doesn't modify the input.mp4 video in any way, and it doesn't produce a new video. It's just for preview / playback purposes.

FFmpeg video crop examples

Let's look at a basic FFmpeg crop example in which we'll crop a square of 100 pixels from the center.

To crop a square of 100 pixels (so both the width and height of the cropped region is 100 pixels) from the center of input.mp4 video, you could specify only the input area size of 100x100 (since the FFmpeg crop filter defaults to the center if the x and y values are not specified), like this:

ffmpeg -i input.mp4 -filter:v "crop=100:100" output.mp4

FFmpeg crop example: crop a section of 100x100 from the top left of the video.

To crop a section of 100x100 pixels from the top left (so the x and y are 0) of a video, use:

ffmpeg -i input.mp4 -filter:v "crop=100:100:0:0" output.mp4

FFmpeg crop example: crop the 100x100 pixels top right section of a video.

Example in which we'll use the input video width (iw) to crop the top right 100x100 pixels section of a video. Instead of manually entering the x value we'll use iw and subtract 100 pixels from it:

ffmpeg -i input.mp4 -filter:v "crop=100:100:iw-100:0" output.mp4

FFmpeg crop example: crop a rectangle of 100x200 pixels from position 0,100.

To use the FFmpeg crop video filter to crop a rectangle of 100x200 pixels from position 0,100:

ffmpeg -i input.mp4 -filter:v "crop=200:100:300:100" output.mp4

Related: FFmpeg: Extract Audio From Video In Original Format Or Converting It To MP3 Or Ogg Vorbis

A couple of more advanced examples:

Crop a 16:9 video to 4:3 aspect ratio, cutting off the edges (source; this doesn't work with images so there's no screenshot to exemplify it, but it should be obvious what it does anyway):

ffmpeg -i input.mp4 -filter:v "crop=ih/3*4:ih"

Crop 50% width and height starting from the top right of the input video.

Crop 50% of the video width and 50% of the video height (which means the output video will be a quarter - 25% - of the input video), starting from the top right of the input video:

ffmpeg -i input.mp4 -filter:v "crop=iw*(5/10):ih*(5/10):iw:0" output.mp4

In this case we're using the input width (iw) as the x coordinate (to start cropping from the right), and 0 as the y coordinate (to start from the top).

You might also like: How To Download A YouTube Playlist And Convert It To MP3 Using youtube-dl (Command Line)

Using FFmpeg to crop pixels from the video left and/or right or top and bottom borders

To crop the borders of a video using FFmpeg (top, bottom, left and right borders), use:

ffmpeg -i input.mp4 filter:v "crop=iw-n:ih-n" output.mp4

In this command you already know that iw represents the width of the input video, and ih is the height of the input video (in pixels); as for n and m:

• n is the number of pixels to crop out of iw (input video width)
• m is the number of pixels to crop out of ih (input video height)

Example.

To crop 200 pixels from the input video height (ih), meaning to crop 100 pixels from the top and 100 pixels from the bottom, and crop 100 pixels from the input video width (iw), meaning to crop 50 pixels from the left and 50 pixels from the right:

ffmpeg -i input.mp4 filter:v "crop=iw-100:ih-200" output.mp4

If you know / can specify the input video width and height (500x300 in this example), the above command can also be written as:

ffmpeg -i input.mp4 filter:v "crop=500-100:300-200" output.mp4

This is also the same:

ffmpeg -i input.mp4 filter:v "crop=400:100" output.mp4

To only crop the left and right borders (100 pixels from the left and 100 pixels from the right, so 200 pixels in total) using FFmpeg:

ffmpeg -i input.mp4 filter:v "crop=iw-200" output.mp4

Or to only crop the top and bottom borders (100 pixels from the top and 100 pixels from the bottom) using FFmpeg:

ffmpeg -i input.mp4 filter:v "crop=iw:ih-200" output.mp4