CEC (Consumer Electronics Control) is the part of the HDMI standard that allows HDMI devices to pass control signals to each other. The most common use of CEC is to allow a video device (like an Xbox or Blu-ray player) to turn on the TV when the video device itself is powered up.
In some cases, CEC signals can have unexpected effects when an HDMI switch is used.
Power Issues
When an Apple TV is used with an HDMI switch, the Apple TV will generally put itself to sleep after several minutes after the switch has been toggled to a difference input. For example, switching from an AppleTV on Input 1 to an Xbox on Input 2 will cause the AppleTV to fall asleep after several minutes. When the AppleTV falls asleep, it will generally send a CEC signal to the TV that will cause the TV to power off, even though the Xbox is being displayed and actively used.
Solution
There are two possible solutions:
- Disable CEC on the AppleTV by turning off the setting at:
Settings → Remotes and devices → Control TVs and recievers - Disable Sleep on the AppleTV at:
Settings → General → Sleep After → Never