It's a Flutter application that provides a basic audio player functionality, using Assets Audio Players plugin.
It's an example for 5 steps for building audio player in Flutter article.
The codebase cannot be treated as completed, as it's just an example. Chances are, you'll need to expand and improve it in your codebase. However, if you find something worth sharing to everyone who would make use of that code, feel free to create a Pull Request!