I am using pulseaudio, but I don't really understand it.
I am recording the audio stream from a video playing in my browser. If I use module-combine-sink, I can record the monitor stream as well as hear it through my headphones. When the video ends, parec stops generating any output. This is great, since I have several multiple-hour video recordings and I don't want to hang around to wait for them to finish.
But I don't always want to send the stream through my headphones. If I use module-null-sink instead of module-combine-sink, I can just record -- but now, parec will keep generating output even after the stream stops playing. When I come back the next morning, I have an enormous output file (I'm piping it to an mp3 compressor, so it's not that big, but still.) The audio I want is at the beginning, and then hours of silence are at the end.
I could probably do it by sending the audio to my laptop speakers instead and muting them, I guess? But I guess I'd like to understand how this is working in the module-combine-sink so maybe I could come up with a more straightforward approach. And I might want to use my speakers for other things while recording, as well.