Due to some licensing issues, many loyal users of what's arguably the best video
player for Android sooner or later find out that the sound in the movies they just loaded for that long-haul flight wouldn't play in MX Player.
We are talking AC3, MLP, DTS or Dolby here, which usually means that if you load a high-res, high-quality container with your favorite TV series, you might be unpleasantly surprised that the sound won't play mid-air, when you don't have access to the Play Store to get an alternative like VLC or KMPlayer.
Moreover, why would you have to give up the amazing MX Player for such a small nuisance? The thing is, you don't, and here is what you have to do to restore full audio codec support with MX Player on your Android device, courtesy of XDA-Dev senior member ktsamy:
1. Download the AIO 1.7.32 codec package zip, and transfer it to default Downloads folder on your Android phone or tablet. This all-in-one package contains the codec versions for hardware decoders there are - Arm v7-Neon, Arm v7-Tegra3, Arm v7-Tegra2, Arm v6 VFP, Arm v6, Arm v5TE, x86, MIPS - preventing you from trying to determine which one you have on your gear;
2. Fire up MX Player, and go to Settings>Decoder>Custom codec (scroll to the end of the list for that one);
3. Point the basic file browser to the aio.1.7.32 zip file you just placed in the Downloads or another folder of choice;
4. The MX Player will automatically pick the right codec for your device, and restart itself to finish the process;
5. If you want to check if the codec pack has definitely been set as default, go to the three context menu dots up right, choose Help>About, and you should see it reading "Custom codec 1.7.32" - this way you will know that the right codec has been installed properly for sure. If for some reason sound doesn't play, check the Settings>Decoder options, and set it to "Use H/W+ decoder" or "H/W+ audio on S/W video," if you have set software video decoding previously for some reason;
6. That's it, you can now play any video file with sound on your beloved MX Player. Enjoy