What is HDMI?

HDMI stands for High-Definition Multimedia Interface. It is a standard that supports high-definition digital video and multi-channel digital audio on a single cable. The HDMI cable connection transmits both video and audio data in a digital format. HDMI connections stand in contrast to analog VGA or DVI connections, which transmit only video data.

What is an HDMI cable?

An HDMI cable is a type of cable that connects a device such as Blu-ray player, game console, or streaming device like a Roku player (and more) to a TV, monitor or projector. It then carries both audio and video signals from the device to the TV. The main difference between an HDMI cable and other cables is that it can carry both uncompressed digital audio and video signals over one cable. There are different versions of HDMI cables, such as HDMI 1.4a, HDMI 2.0a or HDMI 2.1.

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What is an HDMI adapter?

The HDMI standard defines five different connectors that are based upon a 19-pin layout. To convert between different HDMI connectors, you are going to need an HDMI adapter.

The one thing all HDMI adapters or adapter cables have in common is that there is no signal conversion taking place. The HDMI adapter simply makes sure that the 19 pins of the connectors are connected properly on each end. For example, to connect a GoPro to an HDTV requires a Micro HDMI to Standard HDMI adapter. HDMI adapters are also available as HDMI cables with different connectors on each end.

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What is an HDMI converter?

Unlike HDMI adapters, which do not convert the signal, HDMI converters are specifically designed to do just that. An HDMI converter is a device that converts an HDMI signal to another format — and vice versa — so it can be displayed on a monitor or TV. For example, if you have a computer with an HDMI output but your monitor only has VGA input, you will need an HDMI to VGA converter to connect the two. Another common scenario is to connect a DisplayPort-equipped laptop or desktop PC to an HDMI display, for which you will need a DisplayPort to HDMI cable or converter. 

These are three common types of HDMI converters: 

  • HDMI to DisplayPort converter – converters the HDMI signal to a DisplayPort signal
  • HDMI to VGA converter – converters digital HDMI to analog VGA
  • HDMI to DVI converter - changes the input signal from HDMI to DVI

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What is HDMI Alt Mode?

If your USB-C device supports it, HDMI Alt Mode is a standard that can connect an external monitor from the USB-C port without an additional converter in between. This means you can connect your laptop to an HDMI-enabled TV or display and get a clear, uncompressed video feed. However, the standard has not been widely adopted, with many more devices using the far-more popular DP Alt-Mode (which also supports USB-C to HDMI connections).

Applications for HDMI Alt Mode

Connect a USB-C equipped laptop, smartphone, tablet, or desktop PC to an HDMI display, such as a PC monitor, HDTV or projector. HDMI Alt mode is perfectly suited to display the output from your laptop on a 4K big screen TV for video playback. As far as gaming is concerned, the lack of 4K 60 fps (and HDR) may rule out its use for serious fast-paced 4K gaming. On the other hand, if you are limiting yourself to city builders and the likes, you will get great results with HDMI Alt Mode.

How to use HDMI Alt Mode

First, the USB-C device must support the HDMI Alt Mode. Not all USB-C equipped devices do, so this must be confirmed first. Second, you will need a USB Type-C to HDMI adapter cable that supports the standard. This is not a converter, but a simple adapter, and that means that no signal conversion is taking place.

Features of HDMI Alt Mode

The HDMI Alt mode provides the same functionality as HDMI 1.4b. That means you can transmit 4K@30Hz video with 3D, Consumer Electronic Control (CEC), Audio Return Channel (ARC), HDMI Ethernet Channel (HEC) and Dolby 5.1 surround sound audio.

Limitations of HDMI Alt Mode

As the HDMI Alt mode only supports HDMI 1.4b, it lacks features introduced in later HDMI 2.x standards. That includes 4K HDR video, 4k@60Hz and anything higher than that. 

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HDMI for Gaming – Considerations

High-refresh-rate gaming requires components supporting HDMI 2.0 or better, whether you want to run 4K video at 60 fps or 1440p at 144 fps. HDMI 2.0 supports transmission rates of 18.0 Gb/s and because of that, you can play the latest next-gen games in high FPS HDR glory – provided your gaming hardware supports it. 

Future-proof your HDMI gaming hardware with HDMI 2.1 components that provide 4k gaming at 120 fps.

If you are into gaming and are looking for cutting-edge fidelity, you must pay attention to the HDMI specification when shopping for HDMI converters, extenders or HDMI cables.

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Common HDMI Acronyms

Consumer Electronics Control (CEC)

Control of up to 15 connected HDMI devices by using one of their remote controls. As an example, thanks to CEC, you can use your Roku remote to control the volume of your TV, or your home theater system.

Audio Return Channel (ARC)

ARC allows HDTVs with smart apps such as Netflix to send the audio stream from the TV back to the home theater system by using the same HDMI cable that is already connecting them. Thanks to ARC, you do not need additional audio specific cables like coax or TOSLINK.

HDMI Ethernet Channel (HEC)

HDMI Ethernet Channel technology combines audio, data and video streams into a single HDMI cable. HEC enables IP-based applications over HDMI and provides a bidirectional Ethernet communication.

High-dynamic-range (HDR)

High-dynamic-range (HDR) imaging is a technique that captures a greater range of luminosity than a traditional camera, which allows for images with more depth and richer colors. HDR video is a relatively new trend that makes colors more vibrant and realistic. You can see the difference between HDR and normal video by comparing a scene shot in daylight to one shot with an overcast sky. The colors in the daylight scene are brighter and more vivid, while the colors in the overcast scene are duller.

 In PC and console gaming, HDR has become a fixture in recent years with the latest generations of consoles all supporting HDR@4K, including PlayStation 4/5 models, Xbox Series S/X and others. Note that you will need to have an HDR-capable display to take advantage of this technology.

HDR versus Standard

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HDMI Standards and Technical Specifications

The HDMI 2.1 standard is the latest update to the HDMI specification, and it offers several significant improvements over its predecessor. The first is that it supports resolutions up to 8K (7680 x 4320 pixels), which is four times the resolution of 4K (3840 x 2160 pixels). This is important for future television technologies that are being developed now. The second improvement is that the new standard can support data rates up to 42.6 Gbps, which means that HDMI 2.1 can transmit 4K video with a 120 Hz refresh rate, or 8K video at 60 Hz. 

HDMI Standards

SpecificationYearMax. Resolution @ Refresh RateMax. Transmission RateMax. Data RateHDRAudio Support
1.020021080p @ 60 Hz4.95 Gb/s3.96 Gb/snoeight audio channels
1.1/1.220051440p @ 30 Hz4.95 Gb/s8.16 Gb/snoDVD-Audio, One-Bit Audio
1.3/1.420094K @ 30 Hz10.2 Gb/s8.16 Gb/snoARC, Dolby TrueHD, DTS-HD
2.020135K @ 30 Hz18.0 Gb/s14.4 Gb/syesHE-AAC, DRA, 32 audio channels
2.120178K @ 60 Hz48.0 Gb/s42.6 Gb/syeseARC

HDMI Standards

The table below shows the video resolutions and refresh rates of the various HDMI standards. With this information you can quickly know which HDMI standard and, by extension, what kind of HDMI cable you need.

NameVideo
Resolution 
Refresh rate (Hz) Required data rateHDMI 1.3–1.4bHDMI 2.0HDMI 2.1
1080p1920 × 1080301.58 Gbit/ssupportedsupportedsupported
1080p1920 × 1080603.20 Gbit/ssupportedsupportedsupported
1080p1920 × 10801206.59 Gbit/ssupportedsupportedsupported
1080p1920 × 10801448.00 Gbit/ssupportedsupportedsupported
1080p1920 × 108024014.00 Gbit/sonly 4:2:0supportedsupported
1440p2560 × 1440302.78 Gbit/ssupportedsupportedsupported
1440p2560 × 1440605.63 Gbit/ssupportedsupportedsupported
1440p2560 × 1440757.09 Gbit/ssupportedsupportedsupported
1440p2560 × 144012011.59 Gbit/sonly 4:2:0supportedsupported
1440p2560 × 144014414.08 Gbit/sonly 4:2:0supportedsupported
1440p2560 × 144024024.62 Gbit/snoonly 4:2:0supported

HDMI Connectors

There are currently 5 different HDMI connectors: HDMI Type A, B, C, D and E. The most important connectors are the 19-pin HDMI Type A, Mini HDMI Type C and Micro HDMI Type D.

TypePinsSizeApplication
HDMI Type A19RegularDVD/Blu-ray/Ultra HD players, computers, media streaming boxes such as Roku or FireTV,
cable/satellite boxes, and video game consoles
HDMI Type B29RegularObsolete
HDMI Type C19MiniPortable devices such as laptops, tablets or cameras
HDMI Type D19MicroSmall portable devices, incl. smartphones, GoPro type action cameras, small video recording devices and portable media players
HDMI Type E19RegularAutomotive

HDMI Pinouts

While all HDMI connectors have 19 pins, the pinout is not always identical.

HDMI Type A Connector Pinout

By far the most popular HDMI connector, the HDMI Type A connector can be found in most TV sets, media players and streamers, PC graphics cards as well as gaming consoles. 

HDMI Pin NumberSignal
1TMDS Date 2+ 
2TMDS Data 2 shield 
3TMDS Data 2- 
4TMDS Data 1+ 
5TMDS Data 1 shield 
6TMDS Data 1- 
7TMDS Data 0+ 
8TMDS Data 0 shield 
9TMDS Data 0- 
10TMDS Clock+ 
11TMDS Clock shield 
12TMDS Clock- 
13CEC 
14HEC Data- 
15SCL (Serial Clock for DDC)
16SDA (Serial Data Line for DDC)
17DDC / CEC / HEC Ground 
18+5 V Power (50 mA max) 
19Hot Plug Detect (1.3) / HEC Data+ (1.4)

Mini HDMI Type C Connector Pinout

Not nearly as common as the HDMI Type A connector, the Type C connector is still widely adopted in laptops, DSLRs and full-size tablets.

HDMI Pin NumberSignal
1TMDS Data2 Shield
2TMDS Data2+ 
3TMDS Data2-
4TMDS Data1 Shield
5TMDS Data1+
6TMDS Data1-
7TMDS Data0 Shield
8TMDS Data0+
9TMDS Data0-
10TMDS Clock Shield
11TMDS Clock+
12TMDS Clock-
13DDC/CEC Ground
14CEC
15SCL (DDC lock)
16SDA (DDC data)
17HEC+
18+5 V Power (power EDID/DDC)
19Hot Plug Detect/HEC-
-Shell (Ground)

Mini HDMI Type D Connector Pinout

Bringing up the rear, the HDMI Type D connector is the least popular of the three. It can be found on GoPro action cameras and select smartphones.

HDMI Pin NumberSignal
1Hot Plug Detect/HEAC-
2Utility/HEAC+ (NC on device)
3TMDS Data2+
4TMDS Data2 Shield
5TMDS Data2-
6TMDS Data1+
7TMDS Data1 Shield
8TMDS Data1-
9TMDS Data0+
10TMDS Data0 Shield
11TMDS Data0-
12TMDS Clock+
13TMDS Clock Shield
14TMDS Clock-
15CEC (Control)
16DDC/CEC/HEAC Ground
17SCL (DDC clock)
18SDA (DDC data)
19+5 V Power (power EDID/DDC)

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