I have looked into this a few times. There is a number of potential issues with implementing this. First is that I am not sure if ExoPlayer is seeing the track during playback. I am not 100% sure ExoPlayer supports these types of tracks during progressive playback. Second, SageTV does not seem to support this with the Mini Client protocol. If I am able to get it to work, I may cheat and use the Android TV interface to turn it on and off.
I have looked into this a few times. There is a number of potential issues with implementing this. First is that I am not sure if ExoPlayer is seeing the track during playback. I am not 100% sure ExoPlayer supports these types of tracks during progressive playback. Second, SageTV does not seem to support this with the Mini Client protocol. If I am able to get it to work, I may cheat and use the Android TV interface to turn it on and off.
Reference: https://github.com/google/ExoPlayer/issues/6451