One of the most common types of video connections is HDMI (High Definition Multimedia Interface). While computers may have multiple video outputs, many newer consumer video devices (streaming boxes, gaming systems, etc.) only include support for HDMI.
There are multiple versions of HDMI Specifications. Each HDMI specification (i.e., HDMI 1.4b) defines support for various video, audio, and networking (Ethernet) signal formats. Each HDMI standard includes a shopping list of different video resolutions and refresh rates and specifies the technical details for how each of these signal formats is to be supported via HDMI.
For example, a projector would need to support at least HDMI 1.4a to be compatible with consumer HD video sources like a 3D Blu-ray player or gaming system. Higher HDMI specifications offer several user enhancement features and can also support more bandwidth.
It is the higher data rates between the connected A/V devices that makes video enhancements such as higher resolution and frame rates along with greater color depth possible. HDMI 2.1 specification offers much higher bandwidth capability (up to 48Gbps) than HDMI 2.0b (18Gpbs). This higher bandwidth supports a range of higher video resolutions and refresh rates including 8K@60 and 4K@120, and resolutions up to 10K.
Newer HDMI versions are backward compatible with older standards so you can utilize an older HD Blu-ray player with a newer 4K HDR projector. The chart below outlines content type supported by each HDMI specification:
Video Formats Supported
HD (Blu-ray, Set Top Box)
4K@120fps / 8K@60fps
In addition, HDMI also has different levels of copyright protection called HDCP (High-bandwidth Digital Content Protection). Movie studios continue to demand more and more robust copy protection as the quality of available material increases (HD,4K, HDR, 8K) so the purpose of HDCP is to prevent content copying or playback on an unauthorized device. For example, payback of copyrighted 4K SDR/HDR content requires support at least HDCP 2.2. In order to playback HDCP-encrypted content, all the devices in the video signal chain (projector, video switcher, A/V receiver, etc.) must be authorized to playback that level of HDCP content.
For more information on the various HDMI standards, check out the various technical blogs we have written in the past.
Links below are to technical blogs by ART and Phil on the subject of HDMI
HDMI 2.1: The Basics. And, Who Needs It Today – A RantHDMI 2.0 and Support 4K UHD VideoBeyond HDMI 1.4HDMI Version (up to HDMI 1.4)