Result: AC3, DTS, MLP, and TrueHD audio will now work perfectly with hardware decoding.
Solution:
Because the Play Store blocks the download, you must manually install the APK. Warning: Do not trust random "APK download" sites that bundle malware. Follow this safe path: mx player for android 4.1.2
Fix: You downloaded a pirated or modified version. Uninstall it immediately. Get the official free version (1.10.50) which has no license checks. The free version is ad-supported but functions perfectly.
Not every MX Player version works on 4.1.2. The final stable build supporting API 16 is: Result: AC3, DTS, MLP, and TrueHD audio will
MX Player 1.10.50 (released late 2018)
For Android 4.1.2, you need the 1.10.50 armv7-neon codec pack from XDA Developers (search "MX Player custom codec 1.10.50"). Solution: Because the Play Store blocks the download,
On your Android 4.1.2 device: