What is HDMI?
HDMI is an acronym for "High Definition Multimedia Interface". It is a standard for simultaneous transmission of image and sound over a single cable.
For example, HDMI cables carry digital signals from a Blu-ray player to a TV. A digital signal consists of a series of electronic states - namely 0 and 1. There is no "intermediate state". In addition, audio and video signals transmitted over HDMI cables are encoded using HDCP (High-bandwidth Digital Content Protection) technology. The player encrypts the signal, the TV decrypts. The encoded data is sent over the cable with some "redundancy" in case even some 0 and 1 are "lost" along the way. The signal on the TV is fully decoded and reproduced as expected. If the transmission of the HDCP signal is so poor that there is not enough information to decrypt it, then there is no "useful" signal at all. On a TV, these "gaps" will show up as audio and/or video artifacts - these are screeching sounds and/or mosaics in the image. If the interference in the signal exceeds a certain level, the picture and sound will disappear completely.
What types of HDMI cables are there?
Standard HDMI cable
- 720p at 60Hz or 1080i at 60Hz.
- Transfer Speed - From 1.782 Gb/s to 2.25 Gb/s.
- All HDMI versions up to 1.3 are supported.
High-speed HDMI cable
- 2160p (4K) resolution at 30Hz.
- 3D content is delivered in full HD.
- Deep Color technology enhances color depth.
- The transfer rate is at least 8.16 Gbps.
- All HDMI versions up to 1.4 are supported.
Premium High Speed HDMI Cable
- 4K Ultra HD resolution at 60Hz.
- 3D content is also delivered in UHD.
- HDR and 32 audio channels are supported.
- Transfer rate - 18 Gb/s.
- All HDMI versions up to 2.0 are supported.
- Up to 8K resolution at 60Hz.
- Transfer rate - 48 Gb/s.
- All HDMI versions up to 2.1 are supported.
More Features of HDMI Cables
Passive HDMI cables: Most HDMI cables are passive. This means that one end goes to the signal source, the other end goes to the home theater receiver or video display, and the signal is transmitted. The cable is also bidirectional, which means you can connect either end to the HDMI input or output connection. A passive HDMI cable should provide a stable signal up to 15 feet.
Active HDMI Cables: Longer HDMI cable lengths may require additional boost to transmit a stable signal. Active HDMI cables contain amplification circuitry within one of the connectors. In most cases, power is provided internally. However, you may find an active cable that connects to external power via a small cable that runs from the HDMI connector end to either USB power or AC adapter power.
HDMI Optical Cable: Similar to a digital optical audio connection, an optical HDMI cable transmits signals over a fiber optic cable, in this case, both video and audio. HDMI cables have the same type of connections as other HDMI cables. HDMI cables can be made very thin. It can transmit stable signals over longer distances than other HDMI cables without the need for an external power source.
What to look out for when buying an HDMI cable?
- Buy a cable with the correct connector for your device
- Purchase the appropriate cable length. Don't buy a cable that's too long, and make sure it's not so short that you can't move enough components around to provide a convenient connection.
- Too cheap HDMI cables may only transmit signals, and functions like ALLM, VRR, QMS, QFT cannot be reflected