How can I use ffmpeg to change the framerate of a video file?

To change the framerate of a video file using ffmpeg, you can use the following command:

ffmpeg -i input.mp4 -r 30 output.mp4

In this command, "input.mp4" is the name of your original video file and "output.mp4" is the name you want for the new video file with the changed framerate. The "-r 30" flag specifies the new framerate you want to set, in this case, 30 frames per second.