VLC media player is a free and open source cross-platform media player that plays most media files, as well as discs, devices, and network streaming protocols.
+ VLC for Android has a media library for audio and video files, and allows to browse folders directly.
+ VLC has support for subtitles and multitrack audio.
+ Also includes a widget for audio control, supports control of audio headphones, covers and a complete audio media library.

Supported Android
(4.1 and up)
Ice Cream Sandwich (4.0 – 4.0.4),Jelly Bean (4.1 – 4.3.1),KitKat (4.4 – 4.4.4),Lollipop (5.0 – 5.1.1),Marshmallow (6.0 – 6.0.1),Nougat (7.0 – 7.1.1),Oreo (8.0-8.1), Pie(9.0)