Implementing custom Android libaudio.so or "how does audio work on Android?"

I am currently discovering Android> 4.0 and have some questions that I cannot figure out myself, maybe you can help me.

I found out that some market applications like "AlsaMixer" or "MixGet with ALSA" put a library called "libaudio.so" in "/ system / lib /" (by user).

I wondered what was going on and after looking up the timing, it seems like every Android company can create libaudio.so that implemented a specific C ++ interface and put it in that path.

Then Android takes this library for audio processing (are there implementations for ALSA, TinyALSA and others)?

But: My phone doesn't have such libaudio.so - how does it work? What is accepted differently? I found out that I have "libasound.so" in this directory, is this the default?

If I tried to implement my own libaudio.so (with my little knowledge at the moment), can I reference the "default" library in it?

I think, "hey, there is a working audio implementation on the work phone in the world, and I just want to extend it, not re-install (reconfigure) the wheel?"

I mean:

AudioFlinger -> my usual libaudio.so -> default library (libasound.so?) -> speakers

What if I already have libaudio.so on my phone?

I would be very grateful for any helpful answer. Maybe someone has an address for me that a beginner can understand?

Thanks in advance and kind!