HDCP stands for High-bandwidth Digital Content Protection. In short term, this is used to protect 4K material from illegal pirating. Every device in your chain system, must support HDCP 2.2, meaning if your 4K Blue-Ray player has HDCP 2.2, then your Soundbar must support it (SB450 does) and TV as well, or else you won't see any 4K material. In case your TV do not support HDCP 2.2, then it will downscale to 1080P content, this is done by the Blue-Ray player.