MX Player is one of the most reliable players available for mobile platforms, and MX Player Codec is an add-on that will ensure you can play your videos smoothly and without issue. Not all video is made alike. Different formats are encoded in different ways, sometimes even video files of the same format can be encoded using different methods. A video player is simply an engine to decode that video and display it for you, but it needs to know how to decode it, and that's where codecs come in. MX Player Codec for ARMv5 is a codec specifically designed for ARM architecture, meaning you can play your video files without issue on your ARM-based Android device. If you want to play video on your ARM-based mobile device, MX Player is definitely one of the top apps out there. This codec isn't without issues, however. Many users report it failing to play AC3 audio, and that the audio it does play is quieter than other apps. Also, remember, this is a software component for MX Player, not a standalone app.