Get the audio data sent to the soundcard / get the audio data from another application

Hello, I am programming an audio analyzer. That why, I want to retrieve all datas played from another application (for instance: windows media player, microphones (this one I know how to do it) ) in order to process the datas, then sent it to the soundcard. I tried few things with QAudioInput, QAudioOutput or QIODevice without success. I am also using FFmpeg in my program, in case it might help. Do you have any idea how to get the audio data of another software? Thank you, Matt141