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HDMI 2.0 vs HDMI 2.1 – the Key Differences and More on the New HDMI Spec
Jessica Hopkins

The quality of video on our devices has been increasingly significant as our uses for video have become much more embedded within our day-to-day lives for entertainment purposes, gaming, and broadcasting. With many of our devices incorporating video display capabilities, the improvement for video and audio transfer between them has never been more fundamental.

The Evolution of High Definition Multimedia Interface

HDMI, or High Definition Multimedia Interface, was introduced in 2002 as a medium for transferring high definition video and audio signals over a single cable. Throughout the years, multiple iterations of HDMI have been released, but just recently, we’ve been introduced to an all new specification of HDMI that will be widely adopted within the coming years, HMDI 2.1.

black hdmi cable against white background Photo by Srattha Nualsate via Pexels

Here, we will explore HDMI 2.1 further and see how it compares to its predecessor, HDMI 2.0.

How HDMI 2.1 Jumps ahead of HDMI 2.0

One of the major jumps from HDMI 2.0 to HDMI 2.1 is the allotted bandwidth between the two iterations. HDMI 2.0 was first introduced in 2013, delivering a bandwidth of 18 Gbps; with HDMI 2.1, we see a vast increase in bandwidth – 2.6 times greater at 48 Gbps.

This increase in bandwidth is largely due to the increased number of channels and supported bitrate on each channel. The HDMI 2.0 spec, classified as HD or high-speed, uses three data channels, each operating at 6.0 Gbps, with an additional channel supporting the TMDS clock signal. Together, the bandwidth on these three channels can reach up to 18 Gbps.

The HDMI 2.1 spec, classified as UHD or ultra-high-speed, doubles the bitrate per channel to 12 Gbps and also substitutes the 4th TMDS clock channel as an additional data channel. This is possible because the new HDMI spec now uses packet-based data transfer, which embeds a clock signal of its own. Now, with four channels signaling 12 Gbps, 48 Gbps is feasible.

The Dynamics of Improved Vision

Because of the increased bandwidth, the quality of video has greatly improved with the HDMI 2.1 spec. HDMI 2.0 introduced 4K resolution at 60 frames per second, and HDMI 2.1 went further to introduce support for 4K at 120 frames per second, 8K at 60 frames per second, as well as resolutions up to 10K. The 8K resolution quadruples that of 4K, where it now supports 7680 pixels horizontally and 4320 pixels vertically.

Another display improvement we see from HDMI 2.0 to HDMI 2.1 is the new support for Dynamics High Dynamic Range, or dynamic HDR. Dynamic HDR allows the display to alter its contrast and brightness on a frame-by-frame basis. Instead of static HDR used in HDMI 2.0 which uses HDR-10 to apply the metadata once to adjust the display of the television, Dynamic HDR applies metadata at the precise frame, allowing the shadows and brighter frames to become more accentuated.

HDMI 2.1 Cable Improves the Game

Unlike the HDMI 2.0 cable, HDMI 2.1 incorporates additional features that improve the quality of the image and video performance, specifically for gamers. HDMI 2.1 incorporates Variable Refresh Rate, or VRR, which reduces the image lag and enables a 3D graphics processor to display the image at the moment it is rendered creating a smoother image experience. Also, the new Quick Frame Transport and Auto Low Latency Mode features reduce latency, ensuring seamless video that is suitable for fast-paced games.

In terms of the audio transfers within HDMI, the Audio Return Channel, or ARC, function has been implemented within older specs of HDMI, including HDMI 2.0. Traditionally, ARC sends audio signals upstream and downstream over a single connector allowing the cable to send audio from a TV back to an AV receiver or other speaker system. Quality of audio has suffered in previous specs, as the bandwidth to transfer audio was minimal. With the Enhanced Audio Return Channel, or eARC, implemented in the newest HDMI 2.1, this is no longer an issue, as the allotted bandwidth is now 37 Mbps. With the newer spec, more audio content can pass through the cable, and because of this, we can expect higher quality audio outputs.

Upgrade Challenges

With these changes from HDMI 2.0 to HDMI 2.1, there are questions as to whether purchasing all new cables is necessary. Turns out, to get the new features of the higher resolutions or refresh rates, it would require new cables; however, because this spec is relatively new, many televisions have not yet implemented this technology into their devices, so obtaining newer cables may not be imperative at the time being.

How Advanced Cable Tester v2 Supports HDMI 2.1 Design and Production

With the new HDMI 2.1 spec being released into the market, cable manufactures that are incorporating this technology into their products might experience design or production issues. Total Phase offers a cable testing solution for HDMI cables, the Advanced Cable Tester v2.

Users can easily test HDMI cables (spec 2.1 and below) using the HDMI interchangeable connector module with the Advanced Cable Tester v2.

This tool currently supports the HDMI 2.0 spec, as well as earlier HDMI specifications. The Advanced Cable Tester v2 tests a variety of video cables including HDMI and DisplayPort through the use of interchangeable connector modules that attach to the hardware. HDMI manufacturers can expect a comprehensive testing tool that tests for pin continuity preventing shorts and opens, measures DCR, as well as performs signal integrity checks.

Manufacturers can determine whether image and audio outputs meet the relevant specification, with any discrepancies flagged for easy determination of the root cause of any failures. For more information on the Advanced Cable Tester v2 for HDMI cables, please visit our website.