If you’re looking to detect stream up and stream down in real time, the only way to do that as far as I’m aware of is to utilize the undocumented (and unsupported) pubsub topic video-playback. This pull request here Twitch-API pull request, while declined, provides information on the pubsub topic. I just tested it using my library and it appears to be still working.
Again, because this is unsupported, Twitch can (and probably will) change it at any time without any sort of notification.