If you’ve bought an HDTV, a PlayStation, or an HD DVD or Blu-ray player, you’ve probably heard of HDMI. Before we get too far, you’re probably wondering, “What does HDMI stand for??” The answer is “high-definition multimedia interface,” and it is one of many connections to televisions or home theater receivers.
But HDMI is also more than just a port on the back of your TV (or a cable to connect your device to the screen). It’s a set of rules that revolutionized the way people transmit video and audio signals, providing a one-cable solution for a wide range of consumer electronics.
HDMI basics
At its core, HDMI is a proprietary audio and video interface for sending uncompressed video and audio streams between compatible devices. It serves as a digital replacement for previous analog standards, such as video graphic array (VGA) and component video.
Manufacturers debuted the first HDMI version (HDMI 1.0) in 2002. Since then, there have been nearly a dozen revisions, including the following major updates:
The HDMI interface consolidates video transmission, audio output and other data into a single cable. This not only simplifies things, but also allows for the transmission of high-quality audio, making for an overall higher quality viewing and listening experience.
A group of electronics manufacturers developed the HDMI standard as a set of guidelines for establishing high-bandwidth connections between digital devices. With the right setup, HDMI can make a significant difference in a home theater system.
HDMI and 8K
The current standard (HDMI 2.1) can transmit up to 48 gigabytes per second and easily supports 8K (7,680 x 4,320 pixels) or 4K (3,840 x 2,160 pixels) resolutions with much higher refresh rates than the original HD (1,920 x 1,080 pixels).
For example, you can watch in 8K resolution with a 60Hz refresh rate, or you can watch in 4K resolution with a 120Hz refresh rate for the perfect balance of crystal-clear video and super-smooth action.
HDMI can reduce the number of cables needed to connect components, and it can even reduce the number of remote controls you need to watch a movie.
Different types of HDMI connectors
HDMI connectors come in different types for different devices and usage scenarios. Each type is suitable for specific device categories, from basic consumer electronics to portable devices.
There are different types of HDMI cables that correspond to the different types of HDMI connectors. The five primary types of HDMI connectors are:
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HDMI Type A (standard): The standard HDMI connector, also called Type A, is the most common and widely used of the five types of HDMI connectors. Standard HDMI connections are often found in Blu-ray players and home entertainment systems.
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HDMI Type B: Intended for transferring dual-link DVD-I video, this connector became obsolete almost immediately after its release in the early 2000s due to technological advances, so no consumer products use it.
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HDMI Type C (mini): You’ll find a mini HDMI connector on portable devices, such as cameras, tablets, and other small items that require HDMI connections.
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HDMI Type D (micro): Even smaller than a mini HDMI connector, a micro HDMI connector is intended for use in very small, highly portable devices, such as cell phones.
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HDMI Type E (Automotive Connection System): You’ll find these HDMI connectors in cars. They have a unique design that allows them to better maintain audio-video quality despite the vibrations associated with driving.
What do HDMI cables do?
HDMI cables support a range of features and capabilities, such as:
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High-speed HDMI cables: handle high-definition video transmission and enhanced audio return channel.
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HDMI Ethernet Channel: Enables sharing the Internet connection between HDMI devices.
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Audio return channel (ARC): Enables bidirectional audio transmission between HDMI-connected devices, eliminating the need for separate audio cables.
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HDMI Alt Mode: Facilitates HDMI connectivity via alternative interfaces such as USB-C, expanding compatibility with modern devices.
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Enhanced Audio Return Channel (eARC): Improves audio quality and bandwidth for immersive audio experiences, especially with formats such as DTS HD master audio and DVD audio.
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Consumer Electronics Control (CEC): Enables device control via a single remote control, streamlining user interaction in interconnected setups.
You’ll find HDMI on a wide spectrum of devices and applications, including portable devices such as smartphones, tablets and laptops. Here HDMI ports make it possible to watch a video on an external display.
For example, you might want to stream a movie on your laptop, but watch it on your desktop monitor. To do this, you need to connect the two with an HDMI cable.
Likewise, a standard HDMI cable or a high-speed HDMI cable is now an integral part of most home entertainment systems, connecting Blu-ray players, streaming devices, video game consoles and ultra HD TVs.
Outdoors, you’ll find the use of HDMI in professional audiovisual environments, supporting video transmission in commercial displays, projectors and meeting rooms.
Standard definition: the precursor to high definition
HDMI technology and high-definition televisions are now ubiquitous, but that wasn’t always the case.
Before the development of HDTVs, most TVs showed images in what people call standard definition. The image was approximately square, with an aspect ratio of 4:3. The resolution, or the number of dots that make up the image on the screen, was approximately 704 x 480 pixels.
In standard definition, each piece of a moving image was essentially half a photo, but the images changed so quickly that the human brain didn’t really notice. These older TVs relied on analog signals, which travel as a constantly varying electrical current.
The rise of high definition
Unlike standard definition TVs, HDTVs are digital. They use information in the form of ones and zeros. This information travels through cables as separate electrical pulses.
HDTVs have an aspect ratio of 16:9, which makes the image more rectangular. They also have higher resolution: current HDTV standards allow resolutions up to 1920 x 1080 pixels.
HDTV signals can also be progressive, meaning that each frame of the moving image is a whole picture, rather than half of one.
Compared to standard TVs, HDTVs have a wider screen, more pixels and a faster refresh rate.
Often HDTVs can display more colors than older sets. This means that HDTVs need more data and get it much faster than standard definition TVs. If an HDTV can receive this information digitally, it also does not have to spend time or processing power converting the signal from an analog format.
The future of HDMI
Since its inception, HDMI has undergone several revisions to keep up with advancing technologies. Responsible for developing HDMI specifications, the HDMI Forum continually updates standards to support emerging trends such as 8K resolution, high dynamic range (HDR) and enhanced gaming features.
Looking ahead, this type of digital interface will remain the de facto standard for high-quality audiovisual connectivity, ensuring seamless integration between a wide range of devices and applications.
As consumer electronics continue to evolve, HDMI will undoubtedly continue to adapt so that people can continue to enjoy compatibility between their many devices and systems.
We created this article using AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.
Original article: What does HDMI stand for? Here’s how HDMI works
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