This image purpose is to convert unsupported video files by Plex for Raspberry to mp4 which is supported.
Just run the container to convert all videos files to convert recursively on your media volume :
docker run --rm -t -v /path/to/your/media/folder:/media jaymoulin/rpi-plex-video-converter
This image is multiarch, which means it works either on your PC or Raspberry PI
If you don't have Docker installed yet, you can do it easily in one line using this command
curl -sSL "https://gist.githubusercontent.com/jaymoulin/e749a189511cd965f45919f2f99e45f3/raw/0e650b38fde684c4ac534b254099d6d5543375f1/ARM%2520(Raspberry%2520PI)%2520Docker%2520Install" | sudo sh && sudo usermod -aG docker $USER