By creating a DLNA server on your pc you can access to multimedia files like music, videos and audio using DLNA enabled devices within LAN cable or WiFi.
There are both free and commercial software you can use as a server, i list the free ones for Windows.
Serviio written in Java, as you can see has lot of features. It supports many devices and many types of multimedia files that can be played, supports plugins. The program does the streaming of these files both in their native formats or transcoded in realtime (eg. if your tv doesn’t support MKV the program will convert them on the fly in a supported format). The software can also stream online contents.
Another program easy to use is TVersity, i cited it as also available as free version with.