All examples are using uos_flat. uos_flat is a over-layer for uos that takes care about class declarations. You do not have to declare anything in your main application. All methods have a "universal procedurial" syntax. If you prefer to use uos directly, SimplePlayer_noflat shows how to do. This way all methods can be used as oop. (java flavour). Warning: to play Opus files, you should: For Windows: copy /uos/examples/lib/Windows/32bit/libopus-0.dll and paste into your windows/system directory. For Linux/FreeBSD: copy /uos/examples/lib/Linux-or-FreeBSD/64it/libopus.so and paste into /usr/local/lib directory Fre;D