If you are looking for free multimedia player, then you might want to take a look at VLC player. This multimedia player able to play all your media file within your computer. It is free software and opensource. Developed by VideoLAN organisation.
Is it paid software? Absolutely no. This free software is real deal and able to play your most media files. It is free yet available in different platform.
Yes, as you can see there are several version which contained in different platform such as Windows, MacOSX, Linux, Android and also iOS.
From my previous experience, this multimedia player able to play such extension files as mp3, mp4, mkv, avi, m4a and much more when you discovered. The most thing I ever love for this VLC player is it is free from ads and no additional spyware.
You may start downloading the application from here.