What is encoding, and why would I want to do that to my beautiful drone video?
Drones can produce some amazing video. Even modestly priced consumer drones like the Phantom 4 Pro or Mavic 2 have high quality cameras and can produce stunning video in 4K resolution (3840 × 2160 pixels). Playing this high resoultion video on a HD TV works great, in part because the memory card or cable you use to get the video to the TV can easily handle the bandwidth. But putting it on your website is another matter. Not only is that high resolution not useful on a web page (because the resolution most people's screens is much lower than HD), many internet connections can't transfer that much data without a lot of buffering and stuttering issues.
To embed drone video on your website, you generally need to encode it. Encoding typically involves resizing and/or cropping the video, followed by recompressing it to hit a specific playback rate (measured in Mb/s).
Wait! Doesn't YouTube do that?
Yes! In fact the easiest way to share or embed your drone video is to upload it to YouTube, Vimeo, or one of a dozen other video sites. These sites typically encode multiple versions of the video, using multiple settings for size and quality, so they can send whichever version is best for a given user's device and connection speed.
However, there are numerous reasons why you may not want to put your drone video on YouTube. For example you may not like the ads it plays at the end, or would like more control over the filters and how gets encoded. Or you may just want to keep it on-premise. This is where ffmpeg comes in.