No, I'm just talking about the common case where you have some other stuff going on before or after your own audio processing code: a software instrument your f

No, I'm just talking about the common case where you have some other stuff going on before or after your own audio processing code: a software instrument your framework provides, some AudioUnits or gstreamer nodes adding other effects, the whole device chain in the DAW that's hosting you, etc. All of those things need to get done within your window so you can't use the whole thing for yourself. Most people learning audio programming aren't making a standalone audio app where they do all the processing, or at least not an interesting one. They're usually either making something like a plugin that ends up in somebody else's bus/graph, or something like a game or application that creates a bus/graph and shoves a bunch of different stuff into it.