In a 16-bit PCM, MONO recording from android phone, I would like to disable AGC and High Pass filter to get pure MIC recording. Even working with JNI is fine but need direction where to start. Solution should be generic enough to accommodate all android phone and shouldn't be platform specific.
I think this isn't possible.
Even if it is, a non-rooted user surely isn't going to have access to these kinds of settings.
I have some experience with android audio. I work for a company which does VOIP to radio network bridges, we have a smart phone app called TurboVui. I've never heard of this level of control and I've done hours of research into this stuff.
Also I wrote an app called WiFi Speaker which streams audio from your PC to your phone. Again, in all my experience I've never encountered anything like what you're wanting.
Just some background to add a little weight to this opinion.