Adding thumbnail pictures to video files?

Hi guys,

I have a WD MyCloud and stream videos to my tv via a Roku streaming stick.

I have mkv’s, avi’s, and mp4’s which I stream, but when I view them on either my PC or the Roku, the “thumbnail” picture is a still scene from the movie. 

Is there anyway to change this so a picture of the movie poster??

You can create a JPG with the exact same name as the movie, just a different extension, such as

This is my MKV movie.mkv

This is my MKV movie.jpg

For file types that support embedded cover art (such as MP4, M4V), it’s often easiest just to embed the JPG cover as metadata inside the file.