Is it possible to capture the rendering audio session from another process?

Question

I am taking my first dives in to the WASAPI system of windows and I do not know if what I want is even possible with the windows API.

I am attempting to write program that will record the sound from various programs and break each in to a separate recorded track/audio file. From the reseacrch I have done I know the unit I need to record is the various audio sessions being rendered to a endpoint, and the normal way of recording is by taking the render endpoint and performing a loopback. However from what I have read so far in the MSDN the only interaction with sessions I can do is through IAudioSessionControl and that does not provide me with a way to get a copy of the stream for the session.

Am I missing something that would allow me to do this with the WASAPI (or some other windows API) and get the individual sessions (or individual streams) before they are mixed together to form the endpoint or is this a imposable goal?

Answer 1

The mixing takes place inside the API (WASAPI) and you don't have access to buffers of other audio clients, esp. that they don't exist in the context of the current process in first place. Perhaps one's best (not so good, but there are no better alternatives) way would be to hook the API calls and intercept data on its way to WASAPI, if the task in question permits dirty tricks like this.