The Ultimate Guide to HDMI

When you want to connect a high-definition TV, whether it's to watch a movie or play a game, you must have heard of the HDMI Interface, so what exactly is HDMI? In this article, we will conduct an in-depth analysis of HDMI, so that you can understand it in many ways.

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Table of Contents

• What is HDMI?
• History of HDMI
• What is included in the latest version of the HDMI specification?
• What are the HDMI connector types?
• Types of HDMI Cables
• HDMI Alternative Mode (HDMI Alt Mode) for USB-C
• Frequently Asked Questions

What is HDMI?

HDMI is a proprietary digital audio/video interface standard for transmitting high-quality uncompressed video and compressed or uncompressed audio signals over a single cable, and it stands for High Definition Multimedia Interface. Simply put, it is nothing more than an interface description for a cable line that transmits data.

In today's rapidly developing technology, the widespread adoption of HDMI covers almost all modern display devices and media playback devices, such as TVs, computer monitors, game consoles and home theater systems, greatly simplifying the connection between audio and video devices.

History of HDMI

HDMI was originally released in December 2002 by the HDMI Consortium (which includes companies such as Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, and Toshiba.) released to replace analog audio/video cables such as DVI connectors.

Since its release in 2002, versions of the HDMI interface have gone through several revisions, including HDMI 1.0, HDMI 1.1/1.2, HDMI 1.3/1.4, HDMI 2.0 (also known as HDMI UHD), HDMI 2.1, HDMI 2.1a, etc., with the latest version, HDMI 2.1b, being released on August 10, 2023 at the HDMI Forum was released.

To date, HDMI has undergone many subtle changes over the years, but all versions maintain the same basic pinout and are compatible with today's connector types and cables.

What is included in the latest version of the HDMI specification?

The latest version of HDMI is HDMI 2.1b, which builds on HDMI 2.1a by supporting resolutions of 8K60 and 4K120, as well as resolutions up to 10K, dynamic HDR formats for uncompressed 8K video, and 48Gbps bandwidth. And HDMI 2.1b emphasizes the use of ultra high-speed HDMI cables with ultra-low electromagnetic interference (EMI) and compatibility with earlier versions of HDMI devices.

The HDMI specifications for HDMI 2.1b are listed below:
- Supports higher video refresh frequency and resolution for visual feast enjoyment.
- Dynamic HDR ensures that every frame shows detail and a wider color gamut.
- Source-Based Tone Mapping (SBTM) allows the playback device and display to work together to process HDR images, especially when displaying HDR and SDR content at the same time (such as Picture-in-Picture), for a smoother, more natural-looking picture without the need for manual adjustments.
- Enhanced Audio Return Channel (eARC) simplifies connectivity and supports the latest high bit rate audio formats for an immersive experience.
- Enhanced gaming features Variable Refresh Rate (VRR), Automatic Low Latency Mode (ALLM), and Quick Frame Transfer (QFT) make gaming interactions smoother and more immersive.
- The Quick Media Switching (QMS) feature utilizes the HDMI VRR mechanism to eliminate the interruptions that occur when an HDMI source device switches video modes. This avoids a second or two of blackout during video switching.

What are the HDMI connector types?

There are five different types of HDMI connectors. They are Type A (Standard), Type B (Dual Link), Type C (Mini), Type D (Micro), and Type E (Automotive), of which Type B does not have a single actual product that uses it. The details of other common types are as follows:

- Type A connector is the earliest and most common type, most devices including your computer can find this 19-pin connector. And it is the largest of all connectors.
- The C-type connector is also a 19-pin connector that inherits the use of the A-type in a smaller, more compact size. Portable devices like cameras and tablets can be found in them.
- D-type connectors are even more compact than C-type, but still retain the 19 pins of A and C-type, and are mostly used in cell phones and other devices. With the popularity of USB-type c, it is gradually limited to cameras and Raspberry Pi devices.
- The E-type connector focuses on automotive connections and is equipped with a locking tab that prevents the cable from vibrating and thus loosening, making it safer and equipped with a housing that helps protect against moisture and dust, thus avoiding interference with the signal.

Types of HDMI Cables

HDMI cables are categorized into different types due to HDMI certification, and can currently be divided into three main categories: standard cables (supporting 1080i/720p), high-speed cables (supporting 1080p, 4K 30Hz, 3D, etc.), and ultra-high-speed cables (48G cables, supporting 4K 4K, 5K, 8K, and 10K, up to 120Hz).

HDMI 1.3 and HDMI 1.4 define standard and high-speed cables and include Ethernet support.The Premium High-Speed Cable Certification Program, launched in October 2015, introduces EMI testing for improved bandwidth and interference immunity, while the Ultra-High-Speed Cable, released on January 4, 2017, supports the highest performance of HDMI 2.1, maintains backward compatibility, and includes Ethernet .

And the successive HDMI 2.1a added the SBTM feature to HDMI 2.1 to enhance HDR display. The latest version of HDMI 2.1b has been updated slightly to retain all the features and functionality of HDMI 2.1a.

When the HDMI cable is more than 13 meters long, and the signal attenuation due to the cable's structural quality and conductive materials, it is difficult to obtain the official HDMI certification, therefore, in addition to the need to pay attention to the above mentioned interface connector and device interface version when choosing cables, labeled "HDMI Certified" certified cables are more reliable, while the brand can be selected from a variety of options. More reliable, and the brand can choose Belkin , Greenlink, Anker, Monster, etc., the quality is more guaranteed.

HDMI Alternative Mode (HDMI Alt Mode) for USB-C

When the USB type-C interface source device supports the HDMI Alt Mode function, you can connect the device directly to a standard HDMI display device without the need of an adapter by using an HDMI Alt Mode compatible USB type-C to HDMI cable.

DisplayPort Alternate Mode, on the other hand, is less convenient when connecting to an HDMI display via USB type-C, as it requires an active adapter to convert DisplayPort signals to HDMI signals, preventing a native HDMI connection.

However, as announced at CES back in January 2023, HDMI Alternative Mode for USB Type-C is no longer being updated. displayPort Alternative Mode has become the primary video protocol on USB type-C.

Frequently Asked Questions

1. What is HDMI ARC?
HDMI ARC stands for High-Definition Multimedia Interface Audio Return Channel, a technology that enables bi-directional transmission of audio from TVs and audio devices via the HDMI interface, simplifying the connection with a single cable without additional audio cables and enhancing the audio experience.
2. Is DisplayPort better than HDMI?
Both have their own advantages. If you need to connect a TV, game console, Blu-ray player, etc., HDMI is more practical for consumer and entertainment devices, while DisplayPort has a high refresh rate, high resolution, or multi-display setup, which is more advantageous in the professional and industrial fields.
3. Does HDMI to DisplayPort support 165hz?
Yes, but you need to use a high quality active HDMI to DisplayPort converter and make sure the resolution 165Hz refresh rate is supported.
4. What version of HDMI cable is compatible with projector 4k?
Certified cables with HDMI version 2.0 or above (such as Premium High Speed or Ultra High Speed) are compatible with 4K projectors.