Codecs - Sascha-L/WPF-MediaKit GitHub Wiki
Codecs (filters)
WPF-MediaKit requires DirectShow codecs (filters) to be installed on the computer. The most common filters are LAVFilters and ffdshow.
K-Lite codecs pack
There are several free codecs packaging available. A good option is K-Lite. Jus be careful, the installer comes with PUA – potential unwanted applications. You have to uncheck them when installing. Or use Ninite distribution https://ninite.com/klitecodecs/ without PUA.
The K-Lite comes with some helpful tools: MPC-HC player (from Standard variation) and GraphStudioNext (from Full variation).