When you switch to the External Codec option in nPlayer, you are essentially plugging a specialized engine into the app. On iOS, this usually leverages the system’s native capabilities or a specific, optimized library designed to handle complex decoding more efficiently.
For the absolute best experience using nPlayer's codecs, ensure these settings are active: nplayer external codec better
Out of the box, nPlayer uses for decoding. While FFmpeg is powerful, the version shipped with the standard nPlayer app (downloaded from the App Store or Play Store) is often: When you switch to the External Codec option