What is HDMI?

HDMI, or High-Definition Multimedia Interface, is a commonly used standard for concurrently transferring digital imagery and sound from an originating source, 

including computers or TV cable boxes, directed toward an output device such as a monitor, television, or projector. 

Initially introduced by a group of electronics giants, this interface is renowned for its ubiquity as virtually all televisions and computer monitors are compatible.

Back in 2002, the HDMI project was launched with the ambition to better the existing connectivity norms (for instance, DVI, component video) by introducing a trimmer connector, 

infusing internal audio support, and offering a higher-resolution video signal. The impact of HDMI's success was tangible when, 

by 2008, the shipment of HDMI-equipped devices outmatched that of DVI. By the end of 2009, every HDTV boasted at least one HDMI port.

HDMI cables function as the connecting medium within the HDMI interface. By employing an HDMI connector and using a unique HDMI cord, 

a port can transmit high-resolution digital video, high-quality audio, and device instructions. 

Each cord is engineered to support a specific video resolution and features listed in the HDMI specification.

HDMI Cable Types

Cable Type	Resolution	Bandwidth
Standard (Category 1)	1080i or 720p	4.95 Gb/s
Standard with Ethernet	1080i or 720p, plus a dedicated HDMI Ethernet Channel	4.95 Gb/s
High Speed (Category 2)	1080p 4K @ 30 Hz	10.2 Gb/s
High Speed with Ethernet	1080p or 4K @ 30 Hz, plus a dedicated HDMI Ethernet Channel	10.2 Gb/s
Category 3 (4K)	4K @ 60 Hz	18 Gb/s
Category 3 (8K)	8K @ 60 Hz 4K @ 120 Hz	48 Gb/s

HDMI Ports and Connectors

Nowadays, the most common HDMI connectors are Type A (Standard), Type C (Mini), and Type D (Micro), as shown below. 

Though designed for very high-resolution displays, HDMI Type B (Dual Link) was never really implemented. Moreover, 

the HDMI Type E connector, usually used in automotive and industrial settings, is not depicted here.

• Among the five HDMI connector types, the Standard HDMI connector (Type A) is the most extensively used. 

  These 19-pin connectors are found on most brands of TVs, computer monitors, game consoles, streaming devices, and desktop computers.

• Mini HDMI connectors (Type C), too, have 19 pins and provide the same functionality as the full-sized Type A connector, 

  only in a compact form. Due to their smaller size, they are mainly used on portable devices such as DSLR cameras and tablets.

• Micro HDMI connectors (Type D), being the most miniature HDMI connector and about half the width of the Mini HDMI connector, 

  retain the complete functionality of their larger counterparts and can be found on small, portable devices such as smartphones.

Cables are available in male and female versions, with space-saving right-angled connectors and gripping or locking connectors.

HDMI cables are classified as low voltage, which enables their installation within walls. HDMI faceplates offer a tidy and polished look with 

a female connector on the inner side for easy termination. DMI keystones are an available option for digital signage applications 

and large-scale conference facilities, with screens powered from a centralized point.

Grasping and Securing HDMI ConnectorsWhile HDMI connectors don't latch like DisplayPort connectors, a few come equipped with 

a spring mechanism that causes the male connector's blade to grip the socket, thereby reducing the chance of an accidental disconnect. 

If your HDMI device is prone to vibrations or unintended movements, consider using a screw lock connector.

Comparison Between In-wall HDMI Cable and Wireless HDMIA cable connection presents an affordable yet strong and trustworthy signal, 

although its installation may pose challenges. The system is restricted to a single location and to a range of 25-50 ft., contingent on resolution. 

To cover longer spans, an active cable or an HDMI extender is required. Alternatively, a wireless HDMI extender is simpler to install, portable, 

and capable of transmitting a high-resolution signal to multiple recipients.Note: In-wall HDMI cables have either a CL2 or CL3 rating, 

indicating a fire-resistant cable jacket suitable for low-voltage in-wall uses.

Differences in Functionality Among Standard, Mini, and Micro HDMI ConnectorsEach of the three connectors come with the same 19 pins, 

albeit with varying pin assignments. Functionally, they all are equipped to support HDMI 1.4-based resolutions and features.

The Possibility of Using a USB-C Port to Broadcast HDMI to a MonitorYes, it is possible. In Alt Mode, 

selected pins in a USB-C connector are dedicated to the transmission of different protocols. This enables the standard USB-C port/connector 

to serve purposes beyond mere USB data or power. To date, there are four Alternative Modes: DisplayPort, Mobile High-Definition Link (MHL), 

Thunderbolt, and HDMI. The HDMI Alt-Mode supports all features of HDMI 1.4b, including 4K video resolutions at 30 Hz and upwards.

What to Purchase for a 4K TV HDMI CableConsider purchasing a High-Speed HDMI cable that supports HDMI version 1.4 at the least, 

the first version capable of supporting 4K signals. To achieve a 4K display, every component, including the cable box 

or streaming service, HDMI cable, and TV must be 4K compliant. take note that older Standard HDMI cables bought 

before 2009 wouldn't have the required bandwidth to transmit a 4K HDR signal.

Evolution of the HDMI Standard

HDMI 1.0

• Initial release of the HDMI standard

• Audio and video interface for the transfer of video and audio over a single cable

• Data transfer up to 4.95 Gbps

• 1080p at 60 frames per second (UXGA)

• 8-channels of 192kHz/24-bit uncompressed audio (PCM)

• Playback of standard Blu-ray video and audio

HDMI 1.1/1.2

• DVD Audio

• Support for YCbCr color space

• Support for low voltages sources, such as PC video cards using PCI Express

• HDMI Standard (Type A) connector for PC applications

• Consumer Electronic Control (CEC)

HDMI 1.3/1.3a

• Increased bandwidth to 10.2 Gb/s

• Increased color depth to 10-bit, 12-bit, or 16-bit per channel ("Deep Color")

• xvYCC color space support

• HDMI Mini connector (Type C) for use with portable devices such as camcorders

• Support for Dolby TrueHD and DTS-HD Master Audio formats

HDMI 1.4/1.4a

• Support for HDMI Ethernet Channel (HEC)

• Support for 3840 x 2160 at 30Hz and 4096 x 2160 at 24Hz

• Audio Return Channel (ARC)

• HDMI Micro connector (Type D) for use with phones

HDMI 2.0

• Increased bandwidth to 18 Gb/s

• 4K at 60 Hz

• 8b/10b signal encoding

• Support for 32 audio channels

• Support for ultra-wide 21:9 cinema aspect ratio

HDMI 2.1

• Increased bandwidth to 48 Gb/s

• Resolutions up to 10K at 120 frames per second

• Dynamic HDR

• Display Stream Compression (DSC) 1.2a

• Enhanced Audio Return Channel (eARC)

HDMI Features

Transition-Minimized Differential Signaling (TMDS) is a method for encoding an HDMI signal to guard it against interference during transmission, 

particularly over long distances where digital data is vulnerable to noise and signal loss. The process is detailed below:

• the transmitting device encodes the signal, arranging the binary data to minimize the likelihood of signal degradation.

• two duplicates of the signal are sent over separate internal wires; one corresponds to an "out-of-phase" version of the actual signal.

• the receiving device reinstates the out-of-phase signal into its original phase, subsequently comparing both signal versions.

  Any discrepancies (noise) between the two are disregarded.

Consumer Electronic Control (CEC) is a feature that offers users the convenience of managing up to 15 interconnected HDMI devices with a single remote. 

While CEC is supported by a majority of TVs and streaming devices, it might be deactivated as the standard setting. 

It's important to note that manufacturers often brand this feature under different names (for instance, Anynet+ or Viera Link). 

Hence, it might not be immediately noticeable that CEC is supported by your device.

High-Bandwidth Digital Content Protection (HDCP) is an authentication protocol that enables a transmitting and receiving device to cross-check each other's credentials. 

These credentials are stored on the Extended Display Identification Data (EDID) chip of each device. If the devices' credentials match, 

they create a common key to encrypt and decrypt the data exchanged between them. This process is commonly referred to as a "handshake". 

It takes place nearly instantly at the start of a session, fortifying the data against unauthorized interception during its journey from one device to another. 

In the United States, the enforcement of HDCP support is compelled by the Federal Communications Commission (FCC).

Display Data Channel (DDC) refers to the support incorporated into the HDMI interface for VESA DDC. This is a collection of protocols that facilitate a source, 

such as a computer's graphics card, to inquire about and understand the audio and video formats a monitor can process, 

and make necessary adjustments to the monitor settings like brightness and contrast. The data exchanged between a source device and a display, 

known as Extended Display Information Data (EDID), is conveyed via the Display Data Channel.

Chroma Subsampling is a methodology used in video data condensing. Its function is to decrease the volume of color information 

in a video signal but in such a manner that the image quality remains unaffected, or experiences negligible changes.

Every pixel of a video image is composed of details about brightness, also called luma, and color, referred to as chroma. 

Leveraging the human eye's greater sensitivity to brightness variations over color, chroma subsampling lessens the quantity of data transmitted 

by allowing neighboring pixels to share color information.

The representation of chroma subsampling consists of three numbers. The first number represents the pixel count in each sample row. 

The second number signifies the quantity of pixels that carry color details in the TOP row. 

Meanwhile, the third digit reveals the number of pixels in the BOTTOM row that contain color information.

• 4:4:4 means no subsampling. Each pixel has its own color information

• 4:2:2 indicates that two adjacent pixels on each row share color information, representing a 50% reduction in color data

• 4:2:0 means the bottom row has no color information and uses the information provided for the top row. This approach reduces the color data by 75%.

Color Spaces and Deep Color refer to a specific assortment of colors that can depict an image. 

The most prominently utilized color spaces in illustrating digital videos are RGB and YCbCr. 

Color Depth and Gamut stand out as two essential features of a color space. 

Color Depth represents the bit count employed to illustrate a single pixel's color and identifies the level of shading 

or gradation possible. On the other hand, Gamut indicates the array of colors that can be accessed.

The original HDMI specification endorsed 24-bit Color Depth usage (8-bits for each color x 3 colors RGB). 

With HDMI 1.3, Deep Color was introduced, expanding support to include 30-bit, 36-bit, and 48-bit color depths. 

However, it's essential to understand that the human eye can only identify around 10 million unique colors, 

so a 24-bit color typically suffices for most scenarios.

Color Depths

Audio Return Channel, also known as ARC, is a feature that permits a television to transmit audio back to a sound bar 

or AV receiver via the same cable that initially delivered the HDMI signal to the TV. This means it enables both video and audio to be sent to 

the TV and audio to be returned to the sound bar (hence the term "return"). ARC brings about numerous benefits, such as a smaller clutter of cables, 

the convenience of using the TV remote for sound control, and the potential to send high-resolution audio like Dolby TrueHD or DTS HD Master Audio 

to your sound bar or AV receiver. This feature was introduced in Version 1.4.

HDMI Ethernet Channel, also known as HEC, was first unveiled in the HDMI 1.4b specifications. HEC allows devices enabled with Ethernet 

to share an internet connection. It merges the traits of an Ethernet cable within the HDMI cable, thus eliminating the necessity 

for a separate Ethernet cable. Notable examples of devices that can utilize HEC to hook up to the internet include Xbox 360 and Roku. 

This function was introduced in Version 1.4.

Dynamic HDR, or High Dynamic Range, is accomplished by transmitting supplementary information alongside the video signal. 

This extra information instructs the TV or monitor on how to properly showcase the content. Compared to the Standard Dynamic Range (SDR), 

HDR results in increased brightness, improved contrast, and superior color precision. The term "Dynamic" in Dynamic HDR refers to the ability 

to adjust the HDR on a scene-by-scene (or frame-by-frame for advanced TVs) basis.

Enhanced Audio Return Channel, abbreviated as eARC, emerged with the HDMI 2.1 release. It offers increased-quality audio bandwidth and speed support. 

To utilize eARC, you need an HDMI cable with a high speed and Ethernet capability or an Ultra High-Speed HDMI cable. 

eARC doesn't offer backward compatibility with ARC, however, certain products do offer support for both eARC and ARC functionalities. 

This feature was introduced in Version 2.1.

Display Stream Compression, or DSC, operates within HDMI, which uses uncompressed audio and video. 

As the resolution, color depth, and frame rate increase, an increasing number of bits must be transmitted until it hits the bandwidth capacity. 

After reaching this point, the only methods to transmit additional bits are either expanding the transmission lanes within the cable or compressing the signal itself.

With HDMI 2.1, support for Display Stream Compression (DSC) 1.2a was ushered in, enabling visually lossless compression for ultra-high definition (UHD) video. 

Utilizing DSC, an HDMI 2.1 cable can handle a maximum compressed bandwidth of up to 128 Gbps. 

This is ample for 10K resolution, though it will likely take a while before devices requiring such significant bandwidth become commercially accessible.