Resize A Video With FFmpeg

June 2022

TL;DR

This is the FFmpeg command I use to resize videos:

NOTE: If audio doesn't copy try adding -c:a copy

ffmpeg -i "in.mp4" -vf "scale=720:-2" "out.mp4"

It resizes the in.mp4 video to a 720 pixel wide version called out.mp4. The height is determined automatically.

Details

Resizing videos with FFmpeg by adding this to the command:

-vf "scale:WIDTH:HEIGHT"

The WIDTH and HEIGHT can be set to arbitrary values. That includes values that don't match the original aspect ratio which would result in distorted output.

Using -2 on one of the dimensions automatically resizes it to fit the aspect ratio. For example, a 3840x2160 source video resized with this:

ffmpeg -i "in.mp4" -vf "scale=1920:-2" "out.mp4"

produces a video that's 1920x1080.

Putting the -2 on the HEIGHT works as well. For example, this also produces a 1920x1080 video from a 3840x2160 source.

ffmpeg -i "in.mp4" -vf "scale=-2:1080" "out.mp4"

Notes

It's possible to use -1 instead of -2 in the examples above, but it's not recommended. Using -1 matches the aspect ratio exactly which means it could be an odd number. Some filters can't deal with odd numbers. Using -2 ensures the value is even.

TODO

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Link to cropping post - id: 2o4bcmue

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Link to image quality post - id: 2svphsuw

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Look at -c:a copy which might be for audio and might be necessary

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Link to resize with padding example -- id: 2sxx0svx

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Show examples of cropping and resizing

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References

FFmpeg