How to use Imac late 2012 screen as a monitor

[patmac7]

Is there a solution to use my iMAC 27" late 2012 as an external monitor to watch TV from satellite decoder( dreambox). Now I can only stream from box to vlc. I want to input the HDMI output to the screen. Thank you

 

[old-wiz]

Late 2012 is Thunderbolt, which only accepts video in from other thunderbolt Macs.