How to control background music from my Android app?

Question

I want to make an in-app widget, that can pause/play and switch music forward/backward for a lockscreen app for Android. I've tried some different ways, such as working with mediaplayer or Intent, but this didn't help me. I need my app to control music from all the sources: web browser, native music app, social networking apps with music playback support and so on. Something close to that is made in Sony Xperias as a widget. The difference is, that mine won't be a widget, I want it to use inside an application, that replaces the native lockscreen. Hope that my question is clear.

Answer 1

I've found the answer for Android 4+ versions: http://forum.xda-developers.com/showthread.php?p=45288378