Issue link: https://www.e-digitaleditions.com/i/1156106
10 I ICT TODAY HDMI 2.0 and 2.1 HDMI is ubiquitous in the consumer AV market and is widely used in professional AV. It is currently the de facto standard for transporting uncompressed digital video over relatively short distances. In addition to video, HDMI transports compressed or uncompressed audio in stereo or surround sound formats, as well as several control signals that support HDCP handshaking, EDID, consumer electronics control (CEC) and hot plug detect (HPD). All this fits in a 19-pin connector made in sizes from standard to micro. HDMI 2.1, the latest revision to the HDMI standard, pushes bandwidth from the previous 18 Gb/s to 48 Gb/s to support 4K video at 120 Hz refresh rate, 8K/60, and eventually 10K/120. The enhanced refresh rates produce smooth, seamless motion and transitions when viewing fast action, making possible several new features that enhance the viewing experience: • Variable refresh rate (VRR)—Reduces lag, stutter, and frame tearing. • Quick media switching (QMS)—Source devices can switch resolution or frame rate without introducing delays that cause stutter or blank screens during switching. • Quick frame transport (QFT)—Each frame travels faster from source to sink, reducing latency and producing a smooth, no lag experience when viewing real time video content. • Auto low latency mode (ALLM)—Automatically sets the ideal latency for smooth, lag-free, and uninterrupted content for applications ranging from movies to real-time interactive virtual reality. What about audio? HDMI 2.0 already has impressive audio specifications. It allows 32 channels of uncom- pressed audio capable of supporting sound formats up to object-based sound fields like Dolby Atmos. HDMI 2.1 adds more audio capability through enhanced audio return channel (eARC). Legacy ARC allowed simplified cabling by back feeding audio from the display to a surround sound amplifier or sound bar over the same cable delivering video to the display. But, ARC's 1 Mb/s bandwidth compromised audio quality because it used audio compression and a reduced number of sound chan- nels, often only stereo. Currently, eARC at 37 Mb/s can handle uncompressed full resolution audio, supporting all surround sound formats, including 32 channel object-based audio. To take full advantage of HDMI 2.1's high bandwidth, a new ultra high speed HDMI cable is required. HDMI 2.1 cables have better fabrication quality standards, better materials and better shielding than legacy cables. Maxi- mum length for passive cables is 10 feet (3 meters). Active, hybrid optical-copper cables are an option for long runs up to 300 feet (91 meters). The legacy 19-pin connector is retained, allowing backwards compatibility. AV OVER NETWORK INFRASTRUCTURE— UNCOMPRESSED VIDEO OVER TWISTED PAIR Why Use Twisted Pair? Most AV installations require running cables over long distances inside walls and above ceilings. This can be a problem with standard digital AV cable assemblies like HDMI and DVI; the connectors are too large for conduit, and field termination really is not an option for precision connectors. Furthermore, most standard AV cables are not suited for long distances. To meet this challenge, a consor- tium of over 200 companies formed the HDBaseT Alliance to establish a standard for point-to-point transmission of uncompressed AV content over Cat 5e or above twisted- pair cable or optical fiber. HDBaseT uses active transmitter- receiver pairs employing PAM16, which is 16-level pulse amplitude modulated encoding to send digital signals over Category twisted-pair or fiber cable that can be By joining AV design and installation firms or through ICT firms taking a lead role in AV design and installation, RCDD certified personnel become integral members of an AV team.