What Is HDMI? Various HDMI Versions Explained, Compared

Last Updated on May 27, 2022 by Rupesh Patil

Since the inception of HDMI (High-Definition Multimedia Interface) in 2002, the proprietary audio/video interface has been used in more than 10 billion devices. Unless you happen to be Amish, it is quite likely that you own more than one HDMI-capable device. You probably have already used an HDMI cable to connect your monitor to a desktop PC, a laptop, or a PlayStation console to your home theatre system. The more enterprising ones among you may even have used it to bring internet connectivity to your home entertainment devices.

However, HDMI is more than just a cable or a port on your consumer electronics gadget. In its 20-year history, the now ubiquitous interface has gradually evolved to mitigate the mess of cables plaguing our gadgets. But, in doing so, the various iterations of HDMI have ironically become increasingly complicated.

That’s precisely why will dive deep into the HDMI ecosystem to understand what makes HDMI tick, and how the various versions stack against each other.

Why Was HDMI Created?

The dawn of the digital era in the home entertainment space saw different brands introducing their own proprietary formats; each with their own cables, interconnects, and digital standards of communication between devices. It didn’t take long for the rear I/O panel of an AV receiver in the average home theatre setup to have nearly as much cable spaghetti as a poorly maintained data centre.

The major home theatre players soon realised that it would be impossible to make their products appeal to consumers without slaying the cable spaghetti monster their fragmented connectivity standards had created.

Their answer was yet another proprietary connectivity standard called HDMI. Fixing a mess caused by proprietary cables with another proprietary cable might sound like a bad idea, but there’s a method to this apparent madness. Unlike most exclusionary corporate affairs, HDMI is the consumer electronics equivalent of Marvel’s Avengers franchise.

The HDMI specification is the fruit of seven founding companies (Sony, Hitachi, Toshiba, Panasonic, and others) joining forces to standardise the means to connect modern digital devices with digital flatscreen displays that were rapidly replacing existing analogue CRT televisions. The standard is now maintained with inputs and engineering resources contributed by the HDMI Forum comprising 83 electronics stakeholders from various technology sectors, ranging from consumer electronics (LG) to streaming video providers (Netflix).

Additionally, it also boasts of nearly 2000 more companies that have registered as HDMI adopters. This requires them to pay licensing fees and abide by strict rules regarding quality, validation, and logo requirements.

What Is HDMI? How Does It Work?

HDMI (High-Definition Multimedia Interface) is a new interface that has enough bandwidth to carry high-resolution video, uncompressed multi-channel audio, Ethernet (for internet access), and additional digital data (including digital handshake data for anti-piracy measures) upstream and downstream. HDMI primarily serves as the single cable that interfaces with virtually every single piece of equipment in your home theatre setup, while eliminating the need for several different cables and interconnects.

While every compatible device will have an HDMI port and require an HDMI cable, High-Definition Multimedia Interface (HDMI) is more than just an audio/video interconnect. Like Wi-Fi and Bluetooth protocols, HDMI is also a standard or set of preordained rules governing video, audio, and data communication between consumer electronics.

Introduced in 2002, HDMI sets itself apart from the audio/video standards before it by being one of the first digital interconnection standards built from the ground up to support flat, widescreen displays that had begun emerging around that time.

As such, HDMI is used to connect devices as diverse as flatscreen TVs, PC monitors, home theatre receivers, Blu-ray players, video game consoles, media streaming devices, satellite/cable TV boxes, computers, smartphones, and camcorders among many other audio/video devices.

Why Did The Audio-Video Industry Move To HDMI?

The modern flatscreen LCDs displays, which everyone takes for granted, didn’t emerge in the consumer electronics space until the turn of the millennium. In fact, it wasn’t even until 2007 that LCD televisions and monitors began outselling their CRT (Cathode Ray Tube) counterparts. Your average CRT display has a genuine particle accelerator inside it. That’s an incredibly bulky high-voltage device that consumes a lot of power.

This limited the physical size of CRT displays, which also meant that there was no need for resolutions higher than 704×480 pixels found in CRT televisions and monitors that typically averaged 1,280×1,024 pixels.

Furthermore, most consumer-grade CRT televisions used the bandwidth-doubling interlacing technique to display content. Each displayed frame in an interlaced signal is rendered using only alternate lines, with the subsequent frame filling in the omitted half of the picture. However, viewers perceive the two incomplete frames, each containing half the picture information, as a full frame due to the phenomenon of persistence of vision.

In other words, older CRT displays dealt with a minuscule amount of video information thanks to lower resolutions and image rendering tricks, such as interlacing. This allowed the display and consumer electronics industry to get away with analogue video interfaces such as composite, component, S-Video, and D-SUB (VGA).

The thin-film transistor technology used in the newer LCD displays was cheap and compact enough to easily support display resolutions as high as 1920×1080 pixels. Supporting such resolutions requires everything from the cables, ports, and video processing hardware to handle six times the bandwidth required by a conventional CRT television set.

The aforementioned analogue video interfaces wouldn’t cut it anymore in the brave new world of high-resolution flatscreen displays. This prompted the leading display and video electronics companies to band together to create a universally-accepted standard that we now know as HDMI.

All HDMI Versions Explained

HDMI isn’t just a collection of cables, ports, and connectors. Just like the Bluetooth and Wi-Fi standards, it is a set of rules governing interconnectivity between different consumer audio/video electronics products. These standards are set by a consortium of consumer electronics manufacturers, and are expected to be followed by device manufacturers to ensure uniform connectivity.

However, the HDMI standard must be periodically updated to keep pace with the modern computers, video game consoles, televisions, monitors, and media playback devices that tend to evolve rapidly to meet technology advancements and changes in user behaviour. These updates are deployed as revisions to the HDMI standard and represented by alphanumeric version numbers.

Let’s take a look at how the HDMI standard has evolved in conjunction with the consumer electronics space over the 20-odd years of its existence.

HDMI Standards: Specifications Of Various Versions Compared

1. HDMI 1.0

The original HDMI 1.0 standard was codified in December 2002, but the first consumer devices didn’t arrive until the next year. Interestingly, HDMI uses the same digital encoding and signal transmission architecture as the existing Digital Visual Interface (DVI) interface used for computer monitors. However, it broke new ground by using a single cable to funnel video signals along with audio as well as auxiliary data.

HDMI 1.0 allowed a maximum TMDS clock speed of 165Hz, which amounted to a data transfer cap of 4.95Gbps. That was good enough to support 1080p displays at 60Hz, in addition to 8 channels of 192KHz/24-bit uncompressed PCM audio. The additional audio and auxiliary data transmitted along with video data, however, prevented the HDMI standard from catching up to the video resolution capability of the DVI interface until later revisions.

2. HDMI 1.1 and 1.2

The first revision to the HDMI standard was made in 2004 as HDMI 1.1. It added support for the new audio-only DVD-Audio format. A year later, HDMI 1.2 similarly introduced support for the advanced Direct Stream Digital (DSD) encoding used in the high-fidelity Super Audio CD format.

Additionally, it incorporated a few changes meant to make the standard easy to adopt for computer monitors and graphics cards. This involved support for low voltage video sources such as graphics cards and dropping the restrictions on supported video formats. The latter was important to allow the HDMI standard to deal with the dizzying variety of PC video formats.

The update also relaxed the requirement for all HDMI devices to support the YCbCr colour space, since PC graphics cards and displays usually only support the RGB colour space. Other PC-specific improvements included support for 120Hz and 100Hz refresh rates at 720p resolution.

Finally, HDMI 1.2a introduced the Consumer Electronic Control feature allowing a single remote to control multiple connected HDMI-capable home entertainment devices.

3. HDMI 1.3

The HDMI standard received the 1.3 revision in 2006. It significantly improved the bandwidth from 4.95Gbps to 10.2Gbps by bumping up the TMDS clock frequency to 340MHz. This introduced 120Hz high refresh rate mode for the 1080p resolution, in addition to support for larger monitors sporting 2560×1440 pixel screens at 60Hz.

However, the higher frequency signalling warranted stringent quality standards from cable manufacturers, because cables using thinner gauge wires and insufficient EMI shielding and grounding couldn’t reliably achieve such high data transfer speeds. The HDMI forum therefore set Category 1 and 2 cable specifications, thereby differentiating consumer HDMI cables as Standard and High Speed HDMI cables.

The improved video bandwidth could now support deep colour modes with the addition of 10-bit, 12-bit, and 16-bit colour depths. HDMI 1.3 also added compatibility with the xvYCC colour space, which is a wide gamut (deep colour) variant of the YCbCr colour space. HDMI 1.3 also heralded the Type C (Mini HDMI) connector optimised for smaller devices such as DSLRs and camcorders.

On the audio front, the new revision introduced compatibility with high bit-rate Dolby TrueHD and DTS-HD Master Audio formats popularised by Blu-ray around that time. Support for automatic audio/video synchronisation was another entertainment specific addition to the HDMI 1.3 revision.

4. HDMI 1.4

The 2009 HDMI 1.4 update introduced significant changes to the existing cable specifications, with the introduction of the HDMI Ethernet Channel (HEC) that allowed two-way internet and Ethernet communication between connected devices at 100Mbps. The addition of the Audio Return Channel (ARC) was another hardware level addition that allowed the TV to act as the sound source, as necessitated by the increasingly popular smart TVs that incorporated onboard media playback.

HDMI 1.4 was also updated to support 4K televisions, but without improving the bandwidth of existing cable standards. This limited 3840×2160 displays to 30Hz, whereas the wider 4096×2160 aspect ratio displays could only run at 24Hz. The HDMI Forum accommodated the stereoscopic 3D fad, prevalent in the TV and monitor industry at that time, by supporting several popular 3D display formats.

HDMI 1.4 also introduced and even more shrunken down connector dubbed as Type D or Micro HDMI, which was tailored for extremely small devices, such as action cameras and certain types of smartphones and tablets.

5. HDMI 2.0

Released in 2013, HDMI 2.0 was the first revision to offer proper support for 4K or UHD displays. This was achieved by specifying Category 3 cables, which were also referred to as Premium High Speed HDMI cables. These cables could achieve data transfer rates of 18Gbps. This allowed 4K displays to run at full 60Hz, while enabling significantly higher refresh rates for 1080p and 1440p resolutions needed by gaming monitors.

Additionally, it was also possible to support 5K displays at 30Hz. The HDMI 2.0 revision added support for the 21:9 ultrawide aspect ratio displays that were introduced around that time. The higher bandwidth also enabled wide gamut colour spaces, such as the Rec. 2020 colour space, in addition to increasing the audio channel count from 8 to 32, while also bumping up the sampling frequency to 1536kHz.

However, the most significant new feature addition involved support for High Dynamic Range (HDR) video, which eventually became the staple for high-end televisions and computer monitors.

6. HDMI 2.1

Released in 2017, HDMI 2.1 is the latest revision to the format as of this writing. It introduces a new variant to Category 3 cable specification called Ultra High Speed HDMI, which significantly increases bandwidth from 18Gbps to 48Gbps. This was essential to enable HFR (High Frame Rate) support to allow at least 120Hz refresh rates across all supported resolutions. And that’s a challenging prospect since HDMI 2.1 specification introduced support for 8K and 10K displays.

In fact, even the faster 48Gbps cables introduced with HDMI 2.1 cannot support 8K displays at 60Hz. The new Display Stream Compression (DSC) feature, however, allows even 8K and 10K resolutions to be displayed at 120Hz. Speaking of high refresh rate, HDMI 2.1 adds gaming-specific features, such as Variable Refresh Rate (VRR) and Quick Frame Transport (QFT).

VRR is a godsend to eliminate screen tearing and reduce frame pacing issues, such as stuttering and juddering that manifest due to the unpredictable and non-uniform rate at which PC and console GPUs render the display frames. Meanwhile, QFT is specifically aimed at reducing latency associated with image processing. It allows connected HDMI devices to recognise gaming modes and switch off certain processing blocks to reduce latency.

HDMI 2.1 further improves the existing HDR implementation by allowing dynamic metadata control over HDR on a per-scene or per-frame basis. The new Dynamic HDR mode is quickly becoming the staple for high-end televisions and computer monitors. The ARC mode is also upgraded to eARC (Enhanced ARC), which supports a greater number of audio channels necessitated by object-based audio formats such as Dolby Atmos and DTS: X.

A Note On FRL And HDMI 2.1 Backwards Compatibility

Interestingly, HDMI 2.1 has fundamentally moved from TMDS digital encoding process to a brand new FRL (Fixed Rate Link) process. This is necessary to achieve a significantly higher improvement in signal bandwidth and entails silicon level changes to supported hardware, so this cannot be implemented in existing devices with a simple firmware upgrade.

Fortunately, HDMI 2.1 compliant devices are still required to maintain backwards compatibility with the existing TMDS signalling hardware, so all existing HDMI devices will still be inter-compatible with newer HDMI 2.1 compliant devices.

Important HDMI Features: All Benefits Explained

Putting up with blurry picture quality with composite and RF coaxial cables, and the marginally better component and S-Video video interfaces was the norm before the turn of the millennium. Routing analogue video signals through these cables reliably over longer distances was an expensive and complicated affair.

The HDMI interface, however, was designed not only to reliably carry significantly large amounts of video data, but also to reduce the mess of cables in a typical home theatre setup by additionally ferrying audio data, control signals, and other metadata. HDMI also set out to solve other teething issues plaguing typical consumer audio and video devices, while embracing the future of internet-connected equipment.

Let’s take a look at what these HDMI-specific features entail.

1. HDMI Supports High Dynamic Range (HDR) Content

Regular displays lack the colour gamut coverage (a larger colour palette) required to display certain shades of red, blue, and green. This includes vibrant hues, such as the deep red of a fire engine, fluorescent green in neon signs, and the peculiar shade of an eggplant. High Dynamic Range (HDR) displays are inherently capable of rendering a wide gamut of colours, which allows them to show hues that otherwise cannot be displayed by Standard Dynamic Range (SDR) displays.

Furthermore, because human eyes are more sensitive to differences in brightness than colour, certain hues can only be created at elevated brightness levels. This is why good HDR displays need to achieve around 1000 nits of brightness to display such colours and create the sort of contrast required by HDR content. HDR capable devices can therefore naturally render images with wider colour gamut and higher contrast ratios, while achieving unusually high brightness levels required to render certain colours.

HDMI improves the HDR implementation further by enabling dynamic HDR support. This allows the dynamic range to be set on a per scene or even at a frame-by-frame basis to make optimal use of the technology. The HDR content is equipped by metadata that allows content creators to have a much finer control over how the viewer experiences HDR content, by allowing them to dynamically adjust HDR parameters on your display.

2. HDMI Signalling: Digitally Encoded, Error-Correcting

HDMI embraces its digital roots and uses some sophisticated digital signalling techniques to transmit such a large amount of data without any interference or signal degradation. On a purely electrical level, an HDMI cable carries data in twisted pairs.

Doing so not only cancels out EMI (electromagnetic interference), but each twisted cable pair consists of the original signal and an inverse copy of the same. This allows the connected device to compare the two cables in the twisted pair for any discrepancies between the inverse signals and automatically compensate for any errors.

However, the true extent of the HDMI protocol’s error mitigation and correction capabilities become apparent when you take a close look at the way it encodes the digital signal. Just like an analogue signal can degrade while traversing the length of a cable, digital signals are also prone to similar degradation. HDMI combats this by employing transition minimised differential signalling (TMDS) technique to encode data.

As the name suggests, this digital signal processing method relies on reducing the number of transitions between the binary states of data. Doing so further reduces the chances for these digital transitions to be missed on account of transmission losses. The overall data integrity is further bolstered by transmitting error correction data, which allows the receiving equipment to verify whether the data has been received intact and request retransmission if required.

3. HDMI Display Stream Compression (DSC)

As the HDMI standard evolved from its relatively humble 1080p beginnings, it eventually increased the resolution to 4K, followed now by 8K, and the latest HDMI 2.1 standard incorporates support for 10K displays as well. That’s a lot of video information.

To put this into perspective a 1080p display carries 2.1 megapixels worth of video data, whereas 4K weighs in at 8.3 megapixels. Newer 8K TVs require the HDMI cable to pump in 33.2 megapixels of video data per frame. Things get worse when you consider the fact that modern computers and video game consoles can push framerates well beyond 120Hz.

Add 10K displays to the mix and even the massive 48Gbps bandwidth of the latest HDMI 2.1 revision proves inadequate to push such high volumes of video data without some form of video data compression. HDMI already has a technique called chroma subsampling, which reduces video data by allowing neighbouring pixels to share colour data. However, this compression technique is inherently lossy and not quite effective at achieving a higher compression efficiency.

This is where Display Stream Compression (DSC) makes a case for itself by being visually lossless while achieving a high compression ratio. It allows a standard 48Gbps HDMI 2.1 cable to carry a maximum compressed bandwidth of a whopping 128Gbps. This makes it possible to not only support existing 4K and 8K content at high frame rates but it is also future-proofed to accommodate the upcoming 10K displays.

4. HDMI Audio Return Channel (ARC)

The Audio Return Channel is another HDMI feature specifically designed for modern flatscreen televisions. Older analogue televisions usually received both video and audio from a separate source such as VHS or DVD players. However, modern flatscreen televisions can play audio/video content right from the inbuilt and external storage devices, or through streaming devices connected to it.

This means the modern flatscreen TV has now gone from needing audio signals to generating the same itself. That’s fine if you use the TV’s inbuilt speaker system, but flatscreen TVs are plagued by practically unusable speaker setups. This warrants the audio signal to be routed from the TV to external speakers, soundbar, or home theatre receiver through a separate audio cable.

HDMI eliminates this problem by incorporating a separate audio return channel. This effectively eliminates the clutter of an additional cable and the need for users to rummage through settings menus on different devices to get the audio working.

The latest HDMI 2.1 revision has introduced the Enhanced Audio Return Channel (eARC). It leverages the massive 48Gbps bandwidth of the HDMI 2.1 specification to allow HDMI eARC to deliver uncompressed audio data with an impressive resolution of 24-bit/192HKz at 38Mbps. On top of that, it also extends the channel cap all the way up to 32 discrete audio channels.

The new eARC protocol has enough bandwidth to carry uncompressed digital audio formats supported by streaming video apps, but it can also transport most bandwidth-heavy formats found on 4K Blu-ray discs and current-generation video game consoles, such as the PlayStation 5 and Xbox Series X.

5. HDMI Ethernet Channel (HEC)

With a large chunk of the film and entertainment industry moving to the internet with streaming services such as Netflix, YouTube, and countless others, IP-based (internet protocol) applications have become absolutely important for flatscreen TVs. The HDMI Forum acknowledged this fact by implementing the HDMI Ethernet Channel in a later revision (HDMI 1.4) to the standard.

Certain Ethernet-capable HDMI cables can deliver bi-directional internet and Ethernet connectivity between the TV and connected devices at speeds up to 100Mbps. This eliminates the need for separate Ethernet ports and cables to hook up internet-enabled devices within your entertainment setup.

6. HDMI Consumer Electronic Control (CEC)

The modern entertainment system consists of an increasingly complicated mess consisting of a flatscreen TV hooked up to a number of audio and video sources such as Blu-ray players, soundbars, speaker systems, streaming devices, set-top TV boxes, among many others. Each device comes with its own remote controller, which makes it extremely confusing to control a specific device in the home entertainment ecosystem.

The HDMI standard solves this problem by introducing Consumer Electronic Control (CEC) protocol, which lays down the foundation for interoperability between remote controller signalling. It essentially allows the user to control up to 15 connected HDMI-capable devices using a single remote controller. In other words, the remote you use for your TV can also be used to control the basic, everyday functions of your set-top box and Blu-ray player.

Almost all modern HDMI-capable audio/video devices support CEC, but a lot of manufacturers like to use their own brand names for the technology (Samsung’s Anynet+ or Panasonic’s Viera Link). It might not be immediately apparent that your device supports HDMI CEC, so it pays to check the manual if your device implements it under a different brand name.

7. HDCP: The Real Reason Why The AV Industry Loves HDMI

The advent of the VCR or video cassette recorder radically changed the entertainment industry’s attitude towards piracy. After helplessly watching home users make pirated copies of original VHS (Video Home System) film cassettes, Intel developed HDCP (High-bandwidth Digital Content Protection) technology to eliminate piracy at the home user level.

This is achieved by encrypting the digital signals flowing through the HDMI cable in such a way that they cannot be intercepted or otherwise played back by any device that lacks the keys to decrypt the signals. The process of encryption and decryption requires the Extended Display Identification Data (EDID) chips to be present on all HDMI compliant devices, which includes televisions, computer monitors, projectors, Blu-ray/DVD players, video streaming devices, and home theatre equipment.

These chips not only house the encryption keys, but also the unique device identification data that prevents unvetted devices from working with the HDMI interface. The HDMI protocol requires the EDID chips between the source (Blu-ray player) and sink (OLED TV) to establish a digital handshake before data transmission can occur.

This involves the source device verifying the device ID and authentication keys in the EDID chip on the source device. If everything checks out, the source device generates an encryption key that can be used by the sink device to receive signals over the HDMI interface. This security setup prevents unauthorised devices from intercepting encrypted HDMI data. In fact, the HDMI encryption system periodically verifies the encryption keys to ensure link security at all time.

Although this feature adds no practical value to the end user, it sometimes causes encryption handshake errors that outright prevent displays and graphics cards from working with one another and other HDMI devices. However, strong lobbying by the film and entertainment industry and deeply embedded financial interests within the electronics industry have nevertheless ensured widespread adoption of this media encryption system.

HDMI Ports And Connectors Explained

Unlike the confusing USB standard, the HDMI interface has a relatively straightforward selection of ports and connectors. HDMI connectors and ports come in three primary forms dubbed as Type A, C, and D, with each catering to devices of varying sizes.

There’s also the Type E connector that’s beefed up to resist vibration and accidental disconnection for automotive and industrial applications, but it is never found in consumer electronics products. Let’s take a deeper look into what devices each connector is optimised for.

1. Standard HDMI (Type A)

An overwhelming majority of products will ship with the typical Type-A connector and ports. These are the largest consumer-grade HDMI connectors that are equipped with the standard 19-pin configuration and found on virtually all TVs, home theatre equipment, consoles, laptops, and PC graphics cards.

2. Dual-Link HDMI (Type B)

Despite the variation in size, all HDMI ports and connectors support the same basic functionality afforded by the HDMI standard since revision 1.4 and onwards. If you’re wondering why the HDMI forum skipped the letter B, that’s the designation reserved for Type B or dual-link HDMI. This hasn’t been implemented in any known consumer device as of this writing.

3. Mini HDMI (Type C)

The standard HDMI connector is too large for smaller electronic devices such as DSLRs, tablets, and single-board computers such as the Raspberry Pi. That necessitates the Type C or Mini HDMI connector which is significantly smaller, while still accommodating all 19 pins of the Type-A connector. This connector also incorporates the full functionality of its larger counterpart, but still plays well with devices bearing smaller printed circuit boards.

4. Micro HDMI (Type D)

However, some ultraportable devices have even smaller and busier printed circuit boards, where space is at an absolute premium. Tiny action cameras such as the GoPro range and nano-sized portable media players usually prefer the significantly smaller Type D or Micro HDMI ports and connectors. Quite remarkably, the Type D connector retains full HDMI functionality despite assuming half the footprint of a Mini HDMI connector.

5. Specialty HDMI Connectors

Each of the aforementioned types of HDMI interfaces can be further customised to suit specialised needs. This includes panel mount HDMI ports and connectors found in custom video equipment and certain computer cases. Certain device and cable manufacturers also offer right-angled HDMI connectors, which are capable of fitting in tight spaces where the standard HDMI connector is otherwise too long to accommodate.

Also uncommon are HDMI connectors with integrated locks and grips to prevent accidental disconnection ideal for mission-critical applications such as security cameras. Finally, outdoor devices that need weatherproof connectivity are manufactured with specialised water and dustproof housings, which are often rated up to IP68 level of elemental protection.

Demystifying HDMI Cable Types

What Are The Different Types Of HDMI Cables?

Not all HDMI cables are the same. There is such a thing as a slow, outdated HDMI cable that isn’t good enough to carry 4K signals at 60Hz. As of this writing, HDMI cables come in four variants ranging from Category 1 through 3. But, contrary to popular opinion, these category numbers don’t numerically correlate to the HDMI revisions, which are numbered differently as HDMI 1.4, 2.0b, and 2.1 among others.

While HDMI revisions deal with the feature set associated with the entire digital connectivity standard, the cable categories specify the data transfer speed rating of the cables in particular. As explained in our comprehensive Wi-Fi explainer, data transfer speeds are a function of the maximum frequency that the medium can achieve.

1. Standard and High Speed HDMI Cables

That explains why, Category 1 or Standard HDMI cables rated to operate at 74.25MHz are only good for resolutions up to 720p at 60Hz at a maximum bandwidth of 4.95Gbps. Being able to carry 1080p signals at 60Hz requires Category 2 or High Speed HDMI cables running at a higher frequency of 340MHz to achieve a throughput of 10.2Gbps.

Even the Category 2 cables can only support 4K televisions and monitors at 30Hz, which isn’t adequate. Not surprisingly, it is practically impossible to find Category 1 (Standard HDMI) cables out in the wild, with even Category 2 (High Speed) cables being rapidly phased out due to the prevalence of 4K displays capable of higher refresh rates.

A High Speed HDMI cable is the bare minimum required to display 3D content and deep colour signals associated with modern displays.

2. Premium High Speed HDMI Cable

More recently, the HDMI Forum had to revise the format’s specifications to keep up with the growing number of 4K displays that needed to operate at refresh rates of 60Hz. Since the 10.2Gbps bandwidth of Category 2 cables was good for 4K until 30Hz, the HDMI 2.0 specification introduced Premium High Speed (or Category 3) HDMI cables capable of pushing data transfer rates of 18Gbps.

These Category 3 HDMI cables can achieve 4K at 60Hz, while allowing 1080p displays to run at 120Hz. The latter is especially important given the new breed of consoles such as the Xbox One X, Series X, and PlayStation 5 had already brought the concept of 120Hz gaming from PC monitors to living room TVs.

3. Ultra High Speed HDMI Cable

The latest HDMI 2.1 specification, however, requires all resolutions to run at 120Hz. This refresh rate requirement not only includes the now ubiquitous 4K displays, but also extends to the newer 8K televisions and upcoming 10K ones. The existing Category 3 cables marketed as Premium High Speed HDMI cables, however, cannot meet these stringent bandwidth requirements.

This warranted the creation of a new sub-division within the Category 3 cable standard dubbed as Ultra High Speed HDMI cables, which are rated for a bandwidth of 48Gbps and capable of driving 4K, 5K, 8K, and 10K displays at 120Hz. However, the 8K and 10K displays require the HDMI DSC feature to compress video signals to fit within the 48Gbps limit.

It must be noted that all HDMI cable versions are backwards compatible with existing devices and cable standards.

4. HDMI Cable With Ethernet Capability

If all this wasn’t complicated enough, the Standard HDMI and High Speed HDMI cables can come with separate versions that incorporate Ethernet capability. This adds three twisted pairs of conductors specifically meant for bi-directional internet and Ethernet connectivity between the connected HDMI devices. Such cables are essential if you wish to use the nifty HEC (HDMI Ethernet Channel) feature.

Why Is HDMI Still Most Widely Used AV Connector?

While it might seem strange, HDMI has never been the best multimedia interface in terms of pure performance, display bandwidth, or supported resolutions and refresh rates. Even now, the open-source Display Port interface summarily beats it in terms of raw throughput and the number of resolutions supported.

Having said that, nothing else out there enjoys the industry-wide support and the seamless standardisation of essential audio and video features quite like HDMI. For the past two decades, the HDMI Forum has been at the top of introducing industry-standard features and ensuring wider adoption of the same in a timely manner.

Although HDMI might not be the best, it’s still the easiest and most reliable choice for the consumer electronics industry. Not surprisingly, there hasn’t been any comparable alternative to the HDMI standard. And that only means the industry-wide push for standardisation has genuinely worked in the case of HDMI.