Transrating

What? the act of changing the bit rate, or producing other renditions.

Why? people will try to watch your video in a 2G (edge) connection using a less powerful smartphone or in a fiber Internet connection on their 4K TVs therefore you should offer more than one rendition of the same video with different bit rate.

How? producing a rendition with bit rate between 3856K and 2000K.

$ ffmpeg \
-i bunny_1080p_60fps.mp4 \
-minrate 964K -maxrate 3856K -bufsize 2000K \
bunny_1080p_60fps_transrating_964_3856.mp4

Usually we’ll be using transrating with transsizing. Werner Robitza wrote another must read/execute series of posts about FFmpeg rate control.