HDMI - the standard audio and video connection for high-definition home theater gear. In simple words, it is single cable solution for HD video and surround sound audio.
HDMI (High Definition Multimedia Interface) is an interface standard for transmission of encrypted uncompressed digital audio/video data from one equipment to another equipment. HDMI cables connect the interfaces between the devices and are capable of carrying1080p HD video signals at 60fps, which is the most bandwidth hungry video format currently available. Also it can transmit signals in 480p format and NTSC and PAL formats. HDMI cable can carry a bandwidth of 5 Gbps (gigabits per second). HDMI connector types:
There are five types of HDMI connectors:
Type A – It is HDMI version 1.0. It has 19 pins with bandwidth to support SDTV, EDTV, and HDTV. Outside dimensions are 13.9 mm × 4.45 mm and inside dimensions are 14 mm × 4.55 mm. It is electrically compatible with single-link DVI-D.
Type B – It has 29 pins and is capable of carrying double the video bandwidth of type A as it is electrically compatible with dual-link DVI-D. Till date, no device has used the interface and is designed for use with very high-resolution future displays. HDMI Type B is targeted for the motion picture industry and other professional applications. It is also HDMI version 1.0.
Type C – It is HDMI version 1.3. It is a mini connector and is designed for portable devices. It is smaller than the Type A plug connector with the same 19-pin configuration but pin assignment is different. However, type C mini connector can be connected to a Type A connector using a Type A to Type C cable
Type D – It is HDMI version 1.4. It is a macro connector with 19 pins as that of Type A and Type C but shrink connector size, which resembles a micro-USB connector. Its dimensions are 2.8 mm × 6.4 mm (micro-USB connector - 2.94 mm × 7.8 mm).
Type E – It is automotive connection system, which is HDMI version 1.4.
Note: HDMI Type A and HDMI Type B are "Intelligent HDMI," referring to the built-in capability for HDMI-enabled components to talk to each other via the interface.
HDMI version journey:
With HDMI 1.1, it started support for DVD audio.
With HDMI 1.2 modifications, there was an increase in HDMI’s appeal for use in CE and PC industries. It gave support for One Bit Audio format, such as SuperAudio CD's DSD and offered better support for current and future PCs with HDMI outputs.
HDMI 1.3 increases its single-link bandwidth to 340 MHz (10.2 Gbps) to support the demands of future HD display devices. HDMI 1.3 supports 10-bit, 12-bit and 16-bit (RGB or YCbCr) color depths, up from the 8-bit depths in previous versions of the HDMI specification. It offered a smaller form factor connector option, which is suitable for portable devices. It adds additional support for new lossless compressed digital audio formats Dolby TrueHD and DTS-HD Master Audio.
HDMI cables:
HDMI cable is a wire with HDMI interfaces at the both end for transmission of compressed digital data. There is no fixed length for an HDMI cable. However, cable length should not run longer than 16 feet (5 meters), or degradation of the signal could occur.
There are two cable categories for HDMI 1.3 – Category 1-certified cables, tested to perform at speed of up to 74.5 MHz/2.25Gbps, which is the equivalent of a 720p60 and 1080i60 signal and Category 2-certified cable, tested to perform at speeds of up to 340Mhz /10.2Gbps, which is equivalent of a 1080p60 and 2160p30 signal.
Cables of about 5 meters (16 ft) are manufactured to Category 1 using 28 AVG. An HDMI cable can reach lengths of up to 15 meters (49ft) with better quality construction and materials, including 24 AWG conductors.
HDMI cables under 5 meters (16ft) of length that were made before the HDMI 1.3 specification can work as Category 2 cables.
Category 1 HDMI cables are marketed as ‘Standard’ and Category 2 HDMI cables as ‘High Speed’.
Note: Only Category 2-tested cables are guaranteed to work.
Advantages of HDMI over traditional analog video interfaces
Quality: With analog video interfaces such as composite, S-Video and component video, a digital source is translated into less precise analog and sent to the television, and then the content is converted back to a digital signal to display on screen. With each conversion, the digital signal loses some integrity, which results into some distortion of picture quality. HDMI preserves the source signal and delivers the sharpest, richest picture possible as it does not undergo analog conversions. Ease-of-use: Earlier video interfaces required separate audio cables. Most of the people used standard RCA L/R analog audio jacks for transmission of audio. HDMI has abundant bandwidth and speed and it carries not only video but also up to eight digital audio channels for uncompromised surround-sound.
Compactness: HDMI replaces the mesh of wires with a single cable. 19 wires are wrapped in a single cable, which resembles a USB cable. It simplifies cabling and provides high quality home theatre experience by delivering crystal-clear digital content.
HDMI supports standard video formats, enhanced video and high-definition.
Things to know
· Digital connectors such as DVI and HDMI surfaced with the advent of digital TV and introduction of HDTV services. · HDMI delivers the best image quality. It can handle HD video of up to 1080p resolution at 60 fps- highest bandwidth-intensive video format currently available. The older PC-based DVI connection offers equivalent quality, but it is rarely available on HDTVs or video components these days.
· HDMI is the king for audio quality. It supports the ability to carry eight channels of 24-bit audio at 192 kHz, which is enough to handle even the highest resolution audio soundtracks such as Dolby TrueHD and DTS-HD Master Audio. Other connection types that can deliver the same quality are multichannel analog audio cables with eight separate cables, and HDMI can do with single cable only.
· All HDMI versions are fully backward compatible with all previous versions.
· HDMI is fully backward compatible with DVI (Digital Video Interface) compliant devices. High-end graphics cards featuring a DVI port can connect to a HDMI interface via a DVI/HDMI cable (a cable with a DVI connector on one end and a HDMI connector on the other). However, some older PCs with DVI are designed only to support computer monitors, not televisions. Consumers buying a PC with DVI should make sure that it specifically includes support for television formats and not just computer monitors.
· All HDMI products are required to be certified by the manufacturer as part of the HDMI Compliance Test Specification. HDMI Licensing, LLC actively investigates these instances to ensure that the HDMI trademark is properly used in the market. About 700 companies have become the adopters of HDMI standard. Consumers should buy their cables from a reputable source and a company that is trusted.
Why VGA or Composite Cable can’t work?
VGA and Composite video can transmit analog video signals only. They work great for CRT screens and are not preferable for newer LCD screens. Even though many current LCD TVs and computer monitors accept VGA input, they deliver best result with DVI or HDMI (digital connector).
Why HDMI overcomes DVI?
DVI doesn’t support HDCP encryption by default and HDMI supports HDCP encryption for the newest HD content. So, if your hardware only includes DVI ports, you may not be able to playback full HD Blu-rays and other HD content. However, you can connect DVI to an HDMI port on a newer monitor with a small digital convertor. DVI cable doesn’t support audio, so you’ll need to use a separate cable for audio when connecting to an HDMI port while HDMI cables can stream digital video and audio simultaneously over the same cable. However, DVI is one of the most versatile newer connectors. DVI is both backward and forward compatible, undoubtedly with some inconvenience. One can connect an older monitor with a VGA port with a DVI port easily via a similar DVI to VGA converter if video output supports analog video. One can also connect the DVI compatible device with a HDMI via a DVI to HDMI converter.
HDMI is DVI with the addition of features:
a) Support for audio of up to 8-channels uncompressed
b) Smaller connector
c) Support for YUV Color Space
d) CEC -Consumer Electronics Control
e) CEA-861B InfoFrames
Conclusion: HDMI is the best standard for digital multimedia interface. It’s default connector on most devices and screens. It is compatible with HD content including HDCP protected Blu-ray, and can carry video, audio, and more all on single cable.
