High-definition multimedia interface (HDMI) is something that almost all of us recognize. It’s the de facto cable used to play video — especially for anything involving high-definition.
HDMI has been around for more than 20 years, and almost everyone has experience with it. It’s a plug-and-play type of cable, and you probably have one or more of these cables connected to a TV (or more) in your home.
While the essentials of HDMI are easily grasped, there’s a lot more to this technology than most people realize. If you want to know the finer details to ensure you always use the right cable in the right place, then keep reading. This crash course will cover everything you need in just a few minutes.
Types of Connectors
Even though HDMI is a generalized communication method, there’s a lot of variety within the classification. We’re going to be covering a lot of that variety, and the easiest place to start is with connectors and cable types.
Right now, you have three options: types A, C, and D.
Type A is your standard HDMI cable. It has the widest connector of the three, and most computer monitors, DVD players, and smart TV attachments (like a Roku) use this connection type.
You also have Type C, which is known as HDMI mini. This connector is smaller. It shows up on a lot of tablets and other small devices, like cameras.
The third option is Type D, or HDMI micro. It’s an even smaller connector, and it’s used with the smallest devices, such as phones.
It’s worth noting that you can connect devices that mix and match these HDMI types, but you will need adapters to do it. The pin configurations are different for each type of connector, meaning you can’t have a simple cable with an A connector on one end and a D connector on the other end.
In addition to varying connectors, you have different categories for HDMI. While all of them are still decidedly HDMI, the technology has seen updates over the decades, and different categories can achieve different levels of performance.
Here’s a quick breakdown:
- Standard (Category 1): This is the original HDMI cable and it manages 1080i or 720p video. Its maximum data rate is 4.95 Gbps. For reference, this performance is below 1080p, which is the standard for high-definition video.
- Standard + Ethernet: This cable is exactly the same as standard HDMI with one difference. This type of cable has a dedicated HDMI Ethernet channel.
- High Speed (Category 2): This is the first cable that can achieve 1080p resolution (standard high definition). It can also transmit 4k resolutions at 30 frames per second (FPS), and it supports data rates of up to 10.2 Gbps. There is also a High Speed + Ethernet cable, which adds the dedicated channel.
- Category 3: This is your standard 4k cable. It runs 4k video at a normal 60 FPS, and it supports data rates up to 18 Gbps.
- Category 3 8k: This is still a Category 3 cable, but it’s rated for 8k video at 60 FPS, and it supports 4k video at 120 FPS. It’s also the fastest current cable reaching speeds of 48 Gbps. This is the best HDMI cable you can get right now.
You can use that bullet list as a guide. If you want to run video at specific resolutions or frame rates, you’ll need to get HDMI cables of the right category.
But, we’re still not done yet. While HDMI categories can help you shop for the right cables, HDMI standards are set for the IT crowd to keep track of specific metrics. The standards correspond with different categories, which you can see by comparing data rates and resolutions:
- 1.0: The first standard, 1.0 was released in 2002. It supports 1080p video at 60 FPS, handles data rates of 4.95 Gbps, and provides 8 audio channels.
- 1.1/1.2: This combined standard was released in 2005 and supports 1440p video at 30 FPS. It also caps at 4.95 Gbps, and it works with DVD Audio and One-Bit Audio.
- 1.3/1.4: Released in 2009, this standard supports 4k video at 60 FPS. It runs at 10.2 Gbps and supports Dolby TrueHD and DTS-HD.
- 2.0: Since 2013, this has supported 5k video at 30 FPS and speeds of 18 Gbps. It also provides 32 audio channels.
- 2.1: The most recent standard was released in 2017. This supports 8k video at 30 FPS and data rates of 48 Gbps.
A Few More Things You Should Know
We’ve made it through the technical bits, but there are still a few more things that are worth knowing about HDMI. In particular, there are some associated technologies and features that matter in specific scenarios, so we’re covering them now.
Among the topics in this section, HDCP is the most important from a consumer perspective. It stands for High-Bandwidth Digital Content Protection, and this bit of technology is particularly important for media streaming (such as watching Netflix).
In short, this is a protocol that allows a media source to directly communicate with your HDMI device. As an example, a Netflix server can communicate with your smart TV. HDCP allows the two to perform a handshake so they can share and verify credentials. Without this handshake, the stream won’t work.
The primary reason you need to know about this technology is that it can interrupt your ability to consume content. Most streaming services utilize HDCP, and that means you need hardware that is capable of performing an HDCP handshake. Modern devices can do this, but they also have to be connected via HDMI cables that support HDCP.
Typically, HDMI cables can only run for around 50 feet before you start to see signal problems. Transition-minimized differential signaling (TMDS) is a technology that allows HDMI to run longer without signal loss. How much extra length you get varies from one cable design to the next, but if you need extra-long HDMI cables, look for TMDS in your search filters. Then, check the length rating.
Consumer electronic control (CEC) is a convenience feature. Put simply, it allows you to control as many as 15 HDMI devices from a single remote.
Lastly, display data channel (DDC) is a feature that allows the video source to communicate with the video display. As an example, a computer’s graphics card can communicate directly with the monitor to grab information about audio and video formats for a smoother, more streamlined experience.
And with that, you’ve gone through a full course in HDMI. You know more than enough to choose the right cables for any job.