Libre Music is a free and open source media player that lets you simply enjoy your music by being fast, easy to navigate through, and having various other features such as:

* Support for all popular music formats (MP3, FLAC, WAV, etc...)
* Support for CUE sheets and CUE sheets embedded in audio files.
* Modern, simple material design
* Light, Dark and Black themes
* Shuffle and Repeat options
* More to come!

Link to source code: https://bitbucket.org/dannydamsky/libre-music

Libre Music was featured on Android Police "11 new and notable Android apps from the last week (8/22/17 - 8/28/17)" - https://www.androidpolice.com/2017/08/28/11-new-notable-android-apps-last-week-82217-82817/