The HDMI interface appeared in 2003 as a joint development of Hitachi, Philips, Sony, Technicolor, TOSHIBA and other video companies. At that time, it seemed like an almost perfect interface to replace analog connections. After 18 years and 13 versions, starting with HDMI 1.0, there was confusion. It is difficult for an ordinary user to figure out what kind of cable he needs. Let’s take a closer look at the main features of HDMI.
What signal is transmitted and where it is applied
HDMI (High Definition Multimedia Interface) was developed as a standard for the transmission of high definition video. In addition, a digital audio signal is transmitted over the cable at the same time. It is widely used in TVs, computers and laptops, game consoles, monitors, soundbars and many other multimedia devices. Some devices, such as TV, even have 2-3 HDMI connectors: this allows you to simultaneously connect, for example, a PlayStation, a media player and something else. The length of the cable itself for connection usually reaches 10 meters, which is quite enough for a home.
Due to the high bandwidth of the interface (more on that below), an increase in length to 20-30 meters is possible only with the use of so-called signal repeaters.
HDMI cable with built-in repeater that compensates for signal losses over long distances
Active fiber optic cables are used to transmit data over long distances. They are up to 100 meters long and are suitable for large cottages, office and retail premises. There is only one drawback – a very high price in comparison with a conventional cable.
HDMI versions and their differences
There are three current versions of HDMI at the time of this writing. For clarity, we have summarized them in a table. More detailed data, including for outdated versions, can be found in the specialized material .
It is worth considering that the actual throughput of a particular cable is usually higher than stated in the table. For example, at home the author of the article has a 10-meter HDMI version 1.4 from the computer to the TV, however, it is capable of outputting 60 Hz at a resolution of 3840 × 2160, if you set the simplified digital downsampling YCbCr 4: 2: 0 in the video card drivers .
However, to have support for all 4K TV features, including high dynamic range HDR and full FullRGB 4: 4: 4 color gamut, you need cable version 2.0.
If you need to connect state-of-the-art hardware such as an Xbox Series or PlayStation 5 console, the 2.1 cable is essential. Only it can output 120Hz at 4K, and it also supports options like VRR and eARC.
Connector types and pinout
There are four kinds of HDMI slots. Type A is the most common and is used in TVs, laptops, set-top boxes, video cards and other devices. Types C and D are used in tablets or video cameras. Type E is designed for a car.
Structurally, the cable itself consists of 19 cores: four go separately, the rest are assembled in five groups of three wires. The shell is usually made of PVC or nylon, and in expensive models, ferrite beads are added to eliminate interference.
The Type A connector consists of 19 pins , respectively . The first nine transmit the signal, from 10 to 12 – cycle, from 13 to 16 – service, 17 and 18 – this is the ground and 5V power, and the last one is the connection detector.
What are the functions of HDMI
Over the years of development, High Definition Multimedia Interface has acquired many additional bells and whistles.
HDMI CEC (Consumer Electronics Control) allows you to control multiple devices. If an external tuner or set-top box is connected to the TV, you can tune them and change channels from one remote control. Many manufacturers use different names for this function: Anynet + (Samsung), BRAVIA Sync (Sony), Simplink (LG), EasyLink (Philips).
HDMI ARC (Audio Return Channel) is used in soundbars and speakers. If you connect an audio device to the TV port with the corresponding marking, then it automatically synchronizes with it: it turns on and off simultaneously with the TV, the volume can also be controlled from one remote control.
eARC can transmit 7.1 uncompressed audio (versus 5.1 compressed for conventional ARC), as well as high-sampled signal for Dolby Atmos and DTS: X technologies. Only available in HDMI 2.1.
VRR – Variable Refresh Rate, also only available in the latest version of the standard. This feature is analogous to Freesync and G-Sync technologies for monitors, which means that it allows the TV to adjust its refresh rate in real time, rather than using a fixed 60 or 120 Hz. True, only a limited number of TV models support it. Useful for fast-paced games: VRR is available for both the current and next-gen Xbox. Sony has a variable frequency only in the PlayStation 5.
HDMI and DisplayPort do the same thing – they send picture and sound to a device. The difference between the two is that HDMI is used for a wide variety of multimedia devices, while DP is used primarily for connecting monitors.
If we compare the specifications , then DisplayPort 2.0 has a clear advantage – data transfer rates up to 80 Gb / s (versus 48 Gb / s for HDMI 2.1). However, even version 1.3 allows you to connect gaming monitors with refresh rates up to 360 Hz at 1080p, and any HDMI is limited to 240 Hz. DP also supports both dynamic frequency technologies: G-Sync from NVIDIA and Freesync from AMD, HDMI only has support for the latter.