There are so many ways to deal with this issue and one of them is:
Convert an Mp4 to MKV format and visa-versa .
VLC media player is capable enough to play all media file formats, and in case if it cannot play then it will convert it to desired or acceptable format. You can follow these simple steps to get your media files converted:
Install and launch VLC.
- Go to Media > Convert / Save.
- Click Add and find the video file you want to convert.
- Select Convert / Save in the lower portion of the interface.
- In another dialog box, click the Wrench icon, choose AVI in the Encapsulation tab, and click Save.
- Hit Browse and specify a name for the output file. Make sure the name includes the .mkv extension.
- Click Start to convert your video to MKV.