Audio core for cross-platform player?

Question

C++ / C#

Actually, for the purpose of self-learning (and the fact that there are no players under the line that I would like), I decided to make my own player. But then the question arose with the fact that I do not know where to start.
Yes, I understand that you can take ffmpeg to read formats, as an api for accessing the audio system, it’s better to take something like portaudio in order to have a unified frontend, so to speak.
What exactly is of interest: this is the gap between ffmpeg and portaudio, what post-processing of the signal should be carried out (mandatory or optional, for example, resampling), where you need to wedge in a stack of effects and filters (equalizers, etc.). which of these is the de facto standard at the moment.
In general, it would be nice to read something more on this topic. Thank you.

Answer 1

In Qt, the sound is already wrapped qt-project.org/doc/qt-5/multimediaoverview.html , maybe it will be enough to add your plugin there?