Sometimes you need to fiddle with your media before adding them to Plex. Tools to help with modifying your source material. So here is a list of the (free) things I use most frequently (In no particular order).
Use this if you want re-encode your files and you don’t like the command line. Most of what you can do with this can be done with ffmpeg.
A command line alternative to Handbrake.
Extract your Discs to MKV Files.
Does Stuff… I find it useful to clean up / remove metadata from mp4 files, simply run your files through this and your pesky metadata is gone.
Handy toolkit of mkv things. Can Join Files, can remux from mp4 to mkv. As I have mentioned before I prefer to use mkv files, so when I come across mp4 files I simply remux them to mkv with this.