The [RemoteControlClient](http://developer.android.com/reference/android/media/RemoteControlClient.html "RemoteControlClient") was introduced in ICS. That's the way the lock screen seems to be integrating with various music players. See the screenshot below for an example of Spotify on the lock screen.

![enter image description here](https://i.stack.imgur.com/S5fDu.png)

Could one from another app than the lock screen integrate with said players as well?

I find the documentation lacking a bit on the subject, but I think the results, if it's possible, could be interesting.

**Edit:**

Progress so far: none. What I've found out is that **IRemoteControlDisplay** likely has some part in it, but my Android/Java skills are a bit lacking to actually understand how to implement it and achieve the same functionality as on the lock screen.