Hi Mi Fans,
Welcome back to tech class. Today we are going to learn about a new connectivity option – HDMI.
HDMI stands for High-Definition Multimedia Interface. HDMI is a digital replacement for analog video standards.
Before the development of high-definition televisions, most TVs displayed pictures in what is now known as standard definition. The picture was roughly square -- its aspect ratio was 4:3. Its resolution was about 704 x 480 pixels. The pictures changed quickly enough that the human brain didn't really notice. Finally, older TVs relied on analog signals, which travel as a constantly varying electrical current.
HDTVs, on the other hand, are digital. They use information in the form of ones and zeros. This information travels through cables as distinct electrical pulses. HDTVs have an aspect ratio of 16:9, so the picture is rectangular. They also have a higher resolution -- current HDTV standards allow for resolutions of up to 1920 x 1080 pixels.
If an HDTV can receive this information digitally, it also doesn't have to spend time or processing power converting the signal from an analog format. This leads us to HDMI.
The HDMI founders were Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, RCA, and Toshiba. Digital Content Protection, LLC provides HDCP (which was developed by Intel) for HDMI. The HDMI founders began development on HDMI 1.0 on April 16, 2002, with the goal of creating an AV connector that was backward-compatible with DVI.
The HDMI specification defines the protocols, signals, electrical interfaces and mechanical requirements of the standard.
HDMI uses transition minimized differential signalling (TMDS) to move information from one place to another. TMDS is a way of encoding the signal to protect it from degrading as it travels down the length of the cable.
Consumer Electronics Control (CEC) is an HDMI feature designed to allow the user to command and control up to 15 CEC-enabled devices, that are connected through HDMI, by using only one of their remote controls (for example by controlling a television set, set-top box, and DVD player using only the remote control of the TV). CEC also allows for individual CEC-enabled devices to command and control each other without user intervention.
HDMI is backward compatible with single-link Digital Visual Interface digital video (DVI-D or DVI-I, but not DVI-A). No signal conversion is required when an adapter or asymmetric cable is used, so there is no loss of video quality.
There are five HDMI connector types.
This was defined in HDMI 1.0 specification. The plug (male) connector outside dimensions are 13.9 mm × 4.45 mm, and the receptacle (female) connector inside dimensions are 14 mm × 4.55 mm. There are 19 pins, with bandwidth to carry all SDTV, EDTV, HDTV, UHD, and 4K modes. It is electrically compatible with single-link DVI-D.
This was also defined in HDMI 1.0 specification. This connector is 21.2 mm × 4.45 mm and has 29 pins, carrying six differential pairs instead of three, for use with very high-resolution displays such as WQUXGA (3840×2400). It is electrically compatible with dual-link DVI-D, but has not yet been used in any products.
This was defined in HDMI 1.3 specification. This Mini connector is smaller than the type A plug, measuring 10.42 mm × 2.42 mm but has the same 19-pin configuration. It is intended for portable devices.
This was defined in HDMI 1.4 specification. This Micro connector shrinks the connector size to something resembling a micro-USB connector, measuring only 5.83 mm × 2.20 mm. It keeps the standard 19 pins of types A and C, but the pin assignment is different from both.
This was also defined in HDMI 1.4 specification. The Automotive Connection System has a locking tab to keep the cable from vibrating loose and a shell to help prevent moisture and dirt from interfering with the signals. A relay connector is available for connecting standard consumer cables to the automotive type.
From the HDMI connector's pins, signals travel through twisted pairs of copper cable. Three audio and video channels travel through two pins each, for a total of six pins. The TMDS clock, which allows devices to synchronize the incoming data, travels through one pair of pins. Each of these four total pairs has a shield - another wire that protects it from interference from its neighbours. The TMDS channels, the clock and the shields make up the bulk of the cable pairs inside the HDMI cable.
The first consumer products with HDMI connections hit the market in 2003. Since then, there have been several changes to the HDMI standard.
The most recent major revision -- the jump from version 1.2 to 1.3 -- got a lot of attention. New features included a massive increase in bandwidth, support for 16-bit color and support for the xvYCC color standard, which supports additional colors. A new lip-synch feature also reduced that sound and video would fall out of synchronization during playback, making an otherwise immaculate recording look badly-dubbed. Some reports even claimed that any devices that did not have HDMI 1.3 were obsolete.
Fortunately, a lack of 1.3 capability doesn't mean your HDTV is useless. HDMI 1.3 is backwards compatible with previous versions. It's like when color TV debuted. People could watch color TV signals on their black-and-white sets -- the TV still worked, but the picture was still in black and white. If your HDTV has HDMI 1.2 but your new components have HDMI 1.3 capabilities, your TV will still work, but without the expanded 1.3 abilities. Since the bandwidth allotments of previous standards are generally enough for most high-definition applications, your picture should still have a pretty good quality.
HDMI 1.0 was released on December 9, 2002 and is a single-cable digital audio/video connector interface. The link architecture is based on DVI, using exactly the same video transmission format but sending audio and other auxiliary data during the blanking intervals of the video stream. HDMI 1.0 allows a maximum TMDS clock of 165 MHz (4.95 Gbit/sbandwidth per link), the same as DVI. It defines two connectors called Type A and Type B.
HDMI 1.1 was released on May 20, 2004 and added support for DVD-Audio.
HDMI 1.2 was released on August 8, 2005 and added the option of One Bit Audio, used on Super Audio CDs, at up to 8 channels. To make HDMI more suitable for use on PC devices, version 1.2 also removed the requirement that only explicitly supported formats be used. It added the ability for manufacturers to create vendor-specific formats, allowing any arbitrary resolution and refresh rate rather than being limited to a pre-defined list of supported formats.
HDMI 1.3 was released on June 22, 2006, and increased the maximum TMDS clock to 340 MHz (10.2 Gbit/s).
HDMI 1.4 was released on May 28, 2009, and the first HDMI 1.4 products were available in the second half of 2009. It also added an HDMI Ethernet Channel (HEC) that accommodates a 100 Mbit/s Ethernet connection between the two HDMI connected devices so they can share an Internet connection, introduced an audio return channel (ARC), 3D Over HDMI, a new Micro HDMI Connector, an expanded set of color spaces with the addition of sYCC601, Adobe RGB and Adobe YCC601, and an Automotive Connection System.
HDMI 2.0, referred to by some manufacturers as HDMI UHD, was released on September 4, 2013.
HDMI 2.0 increases the maximum bandwidth to 18.0 Gbit/s. This enables HDMI 2.0 to carry 4K video at 60 Hz with 24 bit/px color depth.
HDMI 2.1 was officially announced by the HDMI Forum on January 4, 2017, and was released on November 28, 2017. It adds support for higher resolutions and higher refresh rates, including 4K 120 Hz and 8K 120 Hz. HDMI 2.1 also introduces a new HDMI cable category called Ultra High Speed (referred to as 48G during development), which certifies cables at the new higher speeds that these formats require.
Advantages of HDMI:
The shift from analog to digital interconnectivity has been the biggest trend in home theatre since the introduction of the flat-screen, and installation pros have been leading the way. The combination of superior quality, greater utility, and wider access to content is practically irresistible, here are a few points to consider:
With the exception of a few legacy CRTs and VCRs, just about every CE component in a client’s home these days is likely to be a digital device. So why would anyone opt for an analog connection? Digital-to-analog and analog-to-digital conversions are inherently lossy, and can never match the output quality of a 100% digital system. As well, analog connections compress the video signal. Only a digital connection can fulfill the promise for the best possible video and audio quality.
Access to Content
HDCP is the entertainment industry’s choice for content protection, and it’s only supported by digital interconnects, specifically HDMI and DVI. With any other connection type, viewing premium content like HD-DVD or Blu-ray Disc movies in their full resolution will become increasingly difficult.
When you install HDMI, you can be confident that it will serve the client’s needs for many years to come. Unlike those old analog wires, it’s built for the future of CE technology, not the past.
This is truly a single cable solution as there is only a single cable that carries audio, video and control information. So, the complexity of implementing an audio video control system is lesser.
Disadvantages of HDMI:
HDMI has its own share of diadvantages apart from its benefits.
Maximum distance for HDMI Cat1 cables is up to 35 meters (approx) for full capacity and maximum distance for HDMI Cat2 cables is up to 10 meters (approx) for full capacity. Beyond this limit, they need extenders. There are extenders like UTP cable extenders for HDMI, HDMI cable extenders, Fiber extenders for HDMI and Coaxial extenders for HDMI. Even Switches, Distribution amplifiers, audio/video processors act as repeaters. But extending HDMI cables this way has its limitations.
HDMI cables are more expensive (per meter) than their analog counterparts.
HDMI devices are compatible with DVI interfaces but require a separate audio cable as DVI carries only video signals. It also needs a HDMI-DVI connector in such scenarios.
HDMI at CES 2019
CES stands for consumer Electronics Show which takes place every year and a wide range of consumer products are launched including mobile phones, TVs, etc.
Many of this year’s flagship sets are making the upgrade to HDMI 2.1, which allows far more data to pass through the HDMI cable and will someday enable 4K video at up to 120 fps or 8K at 60fps. It’s also a boost to audio, providing enough bandwidth for uncompressed, 24-bit Dolby Atmos 7.1 over HDMI through eARC.
Major manufacturers confirmed that their new 8K TVs will have HDMI 2.1 connections capable of the full 48-gigabit-per-second transfer speed necessary for the highest-bandwidth forms of 8K.
So, finally we are going to use HDMI 2.1 but the real question is, is there content that can make use of HDMI 2.1's potential?
Sources: 1,2,3Image source
In Case You Missed Previous Threads:
Thanks for reading, Stay tuned for more chapters
In order to fulfill the basic functions of our service, the user hereby agrees to allow Xiaomi to collect, process and use personal information which shall include but not be limited to written threads, pictures, comments, replies in the Mi Community, and relevant data types listed in Xiaomi's Private Policy. By selecting "Agree", you agree to Xiaomi's Private Policy and Content Policy .