To know which platform codecs your device will support, open the MX Player Settings and navigate to the option Decoder. Here, navigate to the bottom of the page and you will find an option that says Custom Codec. You can find the type of codec you must download and use here. If you don’t want to go through all this trouble, there’s an all-in-one pack as well.
Now to install the codecs, download the respective ZIP file and copy it to the root folder of your device’s internal memory. If you are lucky, the MX Player will automatically recognize the file in your SD card the next time you run the app. The app will ask you for a confirmation if you want to use the codec. Just tap the OK button and you are all set. If the app doesn’t detect the codec pack, you can add it manually from the Decoder Settings page.
If you have selected the right codec version for your device, the app will restart automatically after making the changes. If the version is not correct, you will get an error message that says, “Can’t find custom codec for this version”. The best thing to do here would be to opt for the all-in-one file. The app will automatically load the right codec from the pack and restart.
To make sure you have the custom codecs installed on your MX Player, open the Help > About page and here you will find the custom codecs you are using against the version of the MX Player that’s installed on your device