Tangentially, I remember MythTV had support for the self-scheduled variant of this. I used to have a PC with multiple HDDs hooked to the TV and antenna which wo

Tangentially, I remember MythTV had support for the self-scheduled variant of this. I used to have a PC with multiple HDDs hooked to the TV and antenna which would look at its own TV recording schedule and power off when it was idle and wouldn't be recording in the next hour or less. Before powering off, it would set an RTC alarm to wake 10 minutes before the next scheduled recording. Meanwhile, if I walked into the room and wanted to watch recordings while it was off, I would just press the power button let it boot up to use the onscreen UI with IR remote control. I never bothered to figure out if I could make the IR receiver behave in some standby mode to wake the PC. The next time we moved, I couldn't be bothered to set all this up again. Now we just use an old laptop and browser for streaming and a bluetooth keyboard with pointing device for "remote" control. It idles at low enough power to run 24/7 and not care, but we can also just open/close the lid as if it is a sleep switch for the media function.