HDMI is fast gaining ground and changing the face of digital display as we know it. Introduced into the market in 2003, HDMI has undergone tremendous development incomparable to that experienced by analog devices. Well, for those of you who are yet to clue in, a brief lesson on what HDMI is and how it works is definitely in order.
What is HDMI?
HDMI is the acronym for High Definition Media Interface and it refers to a standard set of rules which allow high bandwidth signal connections between different digital gadgets. This makes audio and video signal transmissions better, as seen with HDTVs and other digital devices. Since the high definition devices won’t have to convert the signals from analog to digital, they are protected from degradation. With a HDMI cable, you can kiss the days of using several cables goodbye because it allows you to connect several devices with a single cable—plus you can also use a single remote for all of them.
Technology behind HDMI
HDMI transmits digital data or signals through audio and video interfaces by employing a protocol known as Transmission Minimized Differential Signaling (TDMS). TDMS protects the signals being transmitted by first encoding them before sending from the source to the receiver. This encoding prevents degradation during transmission and is responsible for the high quality picture and sound experienced with HDMI. The process is simple and can be illustrated in the following steps:
- The sender or source device, e.g. a Blu-ray disc player, first reduces the frequency of signal transmission from 1 (on) to 0 (off) by encoding it. Encoding the signal reduces the chances of degradation and ensures that the quality is maintained.
- HDMI uses twisted pair cables; one of them transmits the encoded original signal while the other transmits the inverse version to the receiving device.
- On getting to the receiver, e.g. a high definition TV, the transmitted signal is then decoded. The receiving device does this by measuring the difference between the original signal and its inverse copy to make up for signal losses that occur during transmission.
In essence, HDMI cables are the conduit through which the audio and video signals, and by extension, the HDMI technology can be enjoyed. Since inception, there have been upgrades and revisions ranging from 1.1 to 1.4a, the current standard. However, the cables are no longer referred to as their version numbers; instead, they are referred to as Standard or High Speed Cables with or without Ethernet connectivity.
Standard cables support lower resolutions (such as 1080i or 720p) while High Speed cables support higher resolution displays (such as 1080p). Cables with Ethernet are useful for devices that support the HEC (HDMI Ethernet Channel) with a sending capacity of 100/mbps. In essence it means there are 4 cables viz.: Standard cable, Standard Cable with Ethernet, High Speed cable and High Speed cable with Ethernet. The last cable is the Automotive HDMI cable yet to be commercially available.