HDMI Demystified: Understanding the Numbers

October 03, 2023 HDMI Demystified: Understanding the Numbers

By popular request, Kordz continues its HDMI Demystified article series to delve deeper into the breadth and depth of HDMI technology. HDMI is the ubiquitous connection that almost every AV installation requires. To help you truly get to grips with this sometimes complex subject, we’ve divided it into four distinct parts, each designed to provide you with a clear, digestible and practical understanding of HDMI technology. This is by no means exhaustive of every tiny intricacy of HDMI but it does aim to serve as a useful guide to help AV professionals make better informed choices.

Today, we’ll dive into the significance of HDMI version numbers. These numbers are not just arbitrary labels; they represent the ongoing evolution of HDMI and together we’ll explore how each version brings forth advancements in audio-visual technology. Studying the history of HDMI will not only enrich our knowledge of the technology but it will also aid our grasp of future HDMI developments.

Over the next few months, we’ll release additional instalments of the HDMI Demystified series. Stay tuned to Kordz media channels or, even better, subscribe to the Kordz newsletter to be the first to access the next part of this series.


The world of audio-visual technology has witnessed remarkable transformations over the years. In today’s era, we’re treated to the glories of crystal-clear visuals and immersive audio, thanks in no small part to HDMI, which stands for High-Definition Multimedia Interface. This ubiquitous connection has become the backbone of modern AV devices, seamlessly transmitting high-quality audio and video signals. With nearly 12 billion HDMI-ready devices shipped since the release of the first HDMI specification in December 2002, its impact and prevalence have been nothing short of extraordinary. However, with its success and evolution comes a slew of versions, numbers, and abbreviations that can bewilder even the most AV tech-savvy. In this article, we embark on another journey into the world of HDMI, specifically focusing on understanding the significance of HDMI version numbers so that you can choose the right HDMI devices for your projects with confidence.

Unravelling Cables and Electronics – Names and Numbers 

HDMI version numbers and cable version names often perplex consumers and integrators alike. In fact, HDMI technology encompasses more than just the cable or connector, it involves the entire signal journey, starting with the source device, where the signal is converted into HDMI signal data, then the transmission through the cable, and finally the conversion and processing at the display end, which is also known as the sink device.

The confusion usually arises regarding which versions can support what cables and electronic devices. When we talk about HDMI versions, we typically refer to the capabilities and features of electronic devices, like TVs, projectors, surround processors, game consoles and Blu-ray players. These devices are responsible for processing and displaying video and audio content. On the other hand, HDMI cables serve as the conduit for transmitting signals between these devices. The cable’s role is to support all HDMI versions to ensure compatibility.

The Evolution of HDMI Versions 

HDMI versions now refer solely to the capabilities of the electronics. Over time the HDMI standard has undergone several revisions, each introducing new features and capabilities that build upon the last. The initial concept behind HDMI was to build upon DVI-D by incorporating audio into the mix alongside video. The aim was to establish a direct, point-to-point link between a source and a sink device, such as a display, with a maximum cable length of approximately 3 metres. During this phase, there were no such devices known as repeaters (often AV receivers, splitters, or switches).

1. HDMI 1.x: Laying the Foundation

In the early 2000s, the world of audio-visual technology stood on the brink of a significant transformation and HDMI 1.0 emerged as a key player in ushering in this new era. Introduced in 2002, HDMI 1.0 represented a groundbreaking advancement in the transmission of high-definition video and multi-channel audio. HDMI’s development involved influential founding members, including Sony, Philips, Panasonic, Toshiba, Hitachi, Silicon Image and Thomson. HDMI served as a common technological platform, universally agreed upon by this group of complementary manufacturers. This innovative design encompassed not just the physical form of the interface, which included plugs and sockets, but also the intricate electronics and cable specifications, thus paving the way for a cohesive and unified approach to digital AV connectivity.

Crucially, HDMI 1.0 was designed with the inclusion of HDCP (High-bandwidth Digital Content Protection) 1.0 from the outset. HDCP is a vital component of digital content transmission, ensuring that copyrighted content is securely protected during its journey from the source device to the display. This security measure was necessary to prevent unauthorised copying or interception of digital content, making HDMI an essential standard for content creators and distributors. For many, the integration of HDCP was the primary impetus behind the HDMI specification, aimed at streamlining input/output processes while ensuring secure content transmission.

At its core, HDMI 1.0 aimed to simplify and streamline the complex web of component video, SCART, S-Video Composite video and audio cables that cluttered our entertainment systems. It achieved this by enabling the transmission of both high-definition video and multi-channel audio through a single cable. This marked a significant departure from the previous analogue generation connections, which created a tangled web of cables, each serving a distinct purpose.

HDMI 1.0 was a leap forward in terms of picture quality from Component Video at 720p. It could support resolutions of up to 1080p, offering viewers a new unparalleled level of clarity and detail. This heralded a surge in new AV electronics to cater for this new digital connectivity.

However, HDMI 1.0 to 1.4b (the 1.x series) wasn’t merely about video and audio transmission; it introduced a host of auxiliary features that enhanced the overall user experience. Among these features were ARC (Audio Return Channel), which simplified audio set-ups by allowing audio to be sent from the display back to the source device via the same HDMI cable. Ethernet support was also introduced but facilitating network connectivity through the HDMI cable, making it easier to connect smart TVs and other networked devices. Implementation ethernet over HDMI never really took off and was underutilised, the widespread adoption of Wi-Fi networking killing off any realistically useful application of this feature.

CEC (Consumer Electronics Control) emerged as a significant addition, empowering users to command multiple HDMI-connected devices effortlessly through a single remote control. This streamlined device management sought to declutter our coffee tables by replacing an array of remote controls. Whilst CEC brought convenience, its Initial success depended upon having all HDMI-enabled devices from a single vendor using a form of vendor-specific extended CEC control. Ultimately, in future HMDI versions hijacking the CEC stream for vendor specific commands was banned.

HDMI played a pivotal role in the adoption of HDCP (High-bandwidth Digital Content Protection) as the preferred content protection protocol. Prior to HDMI’s arrival, content protection was primarily reliant on the PAL/NTSC region system. HDMI’s inception transformed the landscape by offering a secure digital interface for transmitting high-definition content, making HDCP an essential component in safeguarding copyrighted material during its transmission, thereby reinforcing HDMI’s status as a foundational standard in the world of audio-visual technology.

HDMI 1.4b stands as a significant milestone within the HDMI 1.x series and marks the culmination of the HDMI founders’ era. With a maximum transmission rate of 10.2Gbps and support for 4K resolution at 30Hz, it signified a notable leap forward. However, it’s worth mentioning that HDMI 1.4b was the last specification entirely crafted by the founding members.

Starting from HDMI 2.0 onwards, the development process shifted to include a more extensive group of contributors within the HDMI Forum. This expansion brought together a diverse array of individuals, which, while enriching the discussion, also extended the time required to formulate new specifications. HDMI’s evolution continued to progress from this juncture. The HDMI Forum, which extended participation beyond its initial core of device manufacturers, particularly TV makers, played a pivotal role in guiding and shaping HDMI’s development. The HDMI Forum comprises professionals and experts from various domains within the audio-visual technology industry, working together to define and enhance HDMI standards. This inclusive approach ensured that HDMI remained at the forefront of technological advancements and met the diverse needs of the AV ecosystem.

2. HDMI 2.0: Catering for the 4K Revolution

Amidst the relentless march of technological progress, HDMI remained adaptable. In 2013, HDMI 2.0 emerged as a crucial response to the surging demand for 4K content, which dominated the landscape of AV marketing and TV sales. HDMI recognised the confusion surrounding version numbers and made a significant change post-HDMI 2.0. The use of version numbers for electronics and cables was abandoned and subsequently forbidden, focusing solely on features. This shift aimed to simplify understanding, yet some misconceptions lingered with many assuming that a 2.0-labelled device inherently supported 4K or multichannel audio. Clarity on specific features became essential to dispel such assumptions and provide accurate expectations for consumers.

One of the primary enhancements of HDMI 2.0 was its ability to support 4K video at a silky-smooth 60 frames per second (fps). This meant that not only could viewers enjoy the increased detail of 4K resolution, but they could also revel in the fluidity of motion that 60fps offered. Content however was scarce and divisive; over the years only been a handful of films being produced in High Frame Rate. The scarcity is likely driven by production cost and its divisive nature is mostly attributable to claims that it lacks the filmic quality of 24 frames per second and somehow looks too real.

HDMI 2.0 also included support for 3D video, adding an extra dimension to the viewing experience. 3D enabled the AV industry to maintain the momentum of sales with even more new hardware required to enable consumers to view 3D content.

Audio enthusiasts had reasons to celebrate too, as HDMI 2.0 introduced enhanced audio features. This made it even more ideal for home theatres, delivering a truly immersive audio experience to complement the visual elements. The audio enhancements included support for higher audio sample rates and up to 32 audio channels.

HDMI 2.0 was a significant step forward, ensuring that our audio-visual technology kept pace with the ever-increasing demand for higher resolutions and richer audio. However, the journey was far from over, as HDMI had its sights set on even grander horizons.

HDMI 2.1: The Leap to 8K and Beyond

In 2017, HDMI unveiled its latest and most ambitious iteration: HDMI 2.1. This marked a quantum leap in the world of audio-visual technology, ushering in an era of unprecedented resolutions and refresh rates.

The most eye-catching feature of HDMI 2.1 was its support for 8K video at 60Hz (10K for commercial applications). This was a monumental leap in resolution, delivering visuals with four times the detail of 4K. It meant that viewers could immerse themselves in the breathtaking clarity of 8K content, the main challenge then becoming the availability of 8K content. Blu-Ray simply couldn’t hold enough information and ushered a new era of even higher movie and television production costs due to the new camera technology, signal distribution and editing required. To date, 8K content is almost as scarce as high frame rate films. It’s been a great marketing strategy for the AV industry, as for the average consumer it’s obvious that 8K must be better than 4K. Although for now, most people with 8K displays are viewing 4K content displayed across four times as many pixels waiting for native content to eventually find its way to them.

HDMI 2.1 didn’t stop at 8K, it pushed the boundaries of refresh rates as well. With support for 4K at a mind boggling 120Hz, it was great for ensuring games were as smooth as silk but a moot point for the traditional movie and TV content viewer.

HDMI 1080 vs 4K vs 8K resolution

Dynamic HDR (High Dynamic Range) was another advanced feature introduced by HDMI 2.1. HDR technology that enriched the quality of visuals by enhancing the dynamic range between the darkest and brightest lightest colours on the screen simultaneously, resulting in more life-like and vibrant images. DSC (Display Stream Compression) was also introduced, a lossless compression technology that allowed for even higher resolutions and refresh rates, reaching a maximum of 8K at 120Hz.

The gaming community once again benefitted, as HDMI 2.1 brought features like Variable Refresh Rate (VRR) and Auto Low Latency Mode (ALLM) to the table. VRR synchronised the display’s refresh rate with the gaming console’s graphics card, reducing screen tearing and providing smoother gameplay. ALLM minimised input lag, ensuring that gamers could react swiftly to in-game actions.

It wasn’t all about gamers though, as audio continued to benefit from HDMI’s advancements with the introduction of enhanced Audio Return Channel (eARC). This feature offered high-quality audio, from the TV as ARC had now become digital, which allowed in-TV apps to deliver surround sound to AV receivers for the first time.

In summary, HDMI 2.1 wasn’t just an incremental improvement, it was a major leap forward into the future of audio-visual technology. It set the stage for the emergence of 8K content and elevated gaming and viewing experiences to unprecedented levels of quality and immersion. HDMI’s journey from its inception to the era of HDMI 2.1 reflects its commitment to delivering cutting-edge technology to our homes and entertainment experiences. As we continue to embrace the potential of HDMI, we can look forward to even more innovations in the world of audio-visual technology, and perhaps one day, a little more native 8K content.

In Summary

As we conclude this initial segment of our journey into HDMI technology, it’s clear that HDMI has undergone a remarkable transformation since its debut in 2002.

HDMI 1.x laid the foundation for the high-definition era by introducing the concept of transmitting both video and audio through a single cable. It marked a significant departure from the clutter of analogue connections and set the stage for the digital revolution. HDMI 1.4b, with its 4K30 support, marked the culmination of this era.

HDMI 2.0 arrived in 2013, catering to the demand for 4K content. It not only delivered 4K60 but also introduced support for 3D video and enhanced audio features, making it ideal for home theatres.

The latest major iteration, HDMI 2.1, which was introduced in 2017, propelled us into the realm of 8K and beyond. With support for 8K60 and 4K120, it brought the future of high-resolution content to our screens. Dynamic HDR, Display Stream Compression, Variable Refresh Rate, Auto Low Latency Mode, and enhanced Audio Return Channel were some of the remarkable features that catered to the diverse needs of both gamers and cinephiles.

Over this time, we’ve witnessed HDMI evolve from a simple connection to a multifaceted standard that supports the ever-increasing demand for higher resolutions, richer audio and immersive gaming experiences.

Coming up next in our HDMI Demystified series, we’ll be unravelling the complexities of HDMI cables and the crucial role they play in ensuring optimal performance of your devices to deliver the ultimate AV experience. To stay updated with Kordz’ newest articles, please follow us on social media or subscribe to our newsletter.

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