HDMI stands for High-Definition Multimedia Interface.
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Here's an Overview from HDMI.org:
Comprised of Hitachi, Matsushita Electric (Panasonic), Royal Philips Electronics, Silicon Image, Sony Corporation, Thomson and Toshiba Corporation, the High-Definition Multimedia Interface (HDMI) Founders have joined together to define a next-generation digital interface specification for consumer
electronics products. HDMI is also supported by major motion picture producers, as well as satellite and cable companies.
HDMI Licensing, LLC is the licensing agent responsible for administering the licensing of the HDMI Specification, promoting the HDMI standard and providing education on the benefits of HDMI to retailers and consumers.
HDMI is an all-digital interface/connection solution that combines both audio and video (instead of separate cables/interconnects). HDMI provides an interface between audio/video sources, such as a DVD player, A/V receiver, digital television, etc. over a single cable.
HDMI was founded by industry giants, and is quickly becoming the standard interface in many audio/video components and consumer electronics (including computers).
Q. What is HDMI?
HDMI (High-Definition Multimedia Interface) is the first and only industry-supported, uncompressed, all-digital audio/video interface. By delivering crystal-clear, all-digital audio and video via a single cable, HDMI dramatically simplifies cabling and helps provide consumers with the highest-quality home theater experience. HDMI provides an interface between any audio/video source, such as a set-top box, DVD player, or A/V receiver and an audio and/or video monitor, such as a digital television (DTV), over a single cable. HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It transmits all ATSC HDTV standards and supports 8-channel, 192kHz, uncompressed digital audio and all currently-available compressed formats (such as Dolby Digital and DTS), HDMI 1.3 adds additional support for new lossless digital audio formats Dolby® TrueHD and DTS-HD Master Audio™ with bandwidth to spare to accommodate future enhancements and requirements. HDMI is the de facto standard digital interface for HD and the consumer electronics market: More than 500 companies have become adopters, and more than 130 million devices featuring HDMI are expected to ship in 2007, with an installed based of nearly one billion HDMI devices by 2010 (conservative estimates by In-Stat). Convergence – HDMI is the interface for convergence of PC and consumer electronics devices: HDMI enables PCs to deliver premium media content including high definition movies and multi-channel audio formats. HDMI is the only interface enabling connections to both HDTVs and digital PC monitors implementing the DVI and HDMI standards. Evolving standard – HDMI is continually evolving to meet the needs of the market: Products implementing new versions of the HDMI specification will continue to be fully backward compatible with earlier HDMI products.
Q. Who supports HDMI?
The HDMI Founders include leading consumer electronics manufacturers Hitachi, Matsushita Electric Industrial (Panasonic), Philips, Sony, Thomson (RCA), Toshiba, and Silicon Image. In addition, HDMI has the support of major motion picture producers Fox, Universal, Warner Bros. and Disney, and system operators DirecTV, EchoStar (Dish Network) as well as CableLabs.
Q. What are the advantages of HDMI over existing analog video interfaces such as composite, S-Video and component video?
Quality: Because HDMI is a digital interface, it provides the best quality of the video since there are no lossy analog to digital conversions as are required for all analog connections (such as component or S-video). The difference is especially noticeable at higher resolutions such as 1080p. Digital video will be sharper than component, and eliminates the softness and ghosting found with component. Small, high contrast details such as text bring this difference out the most.
Ease-of-use: HDMI combines video and multi-channel audio into a single cable, eliminating the cost, complexity, and confusion of multiple cables currently used in A/V systems. This is particularly beneficial when equipment is being upgraded or added.Intelligence: HDMI supports two-way
communication between the video source (such as a DVD player) and the DTV, enabling new functionality such as automatic configuration and one-touch play. By using HDMI, devices automatically deliver the most effective format (e.g 480p vs 720p, 16:9 vs 4:3) for the display that it is connected to - eliminating the need for the consumer to scroll through all the format options to guess what looks best. HD Content-Ready: HDMI devices supporting HDCP have the comfort of knowing they will have access to premium HD content now and in the future. HD-DVD and Blu-ray have delayed the activation of the image constraint token (a.k.a. content protection flag) with today’s HD movies to help minimize potential issues caused by the transition, but are expected to activate this in a few years, meaning future HD movies will then not be viewable at HD resolutions over unprotected interfaces such as analog component.
Q. What is the advantage of using HDMI over existing audio interfaces such as analog RCA connectors and digital SPDIF (coax and optical connectors)?
Quality: HDMI maintains the audio in its pure digital form all the way to the amplifier. Analog audio connections are more prone to losses depending on the cabling and other electronics of the audio rendering device. Compared to SPDIF connections, HDMI has significantly more bandwidth, allowing it to support the latest lossless audio formats such as Dolby TrueHD and DTS-HS Master Audio. These formats can not be supported over SPDIF connections due to their very high data rate requirements that exceed the capabilities of SPDIF.
Ease of Use: HDMI combines video and multi-channel audio into a single cable, eliminating the cost, complexity, and confusion of multiple cables currently used in A/V systems. This is particularly beneficial when equipment is being upgraded or added.
Intelligence: HDMI supports two-way communication between the audio source (such as a DVD player) and the audio rendering device (such as an A/V receiver), enabling new functionality such as automatic
configuration and one-touch play. By using HDMI, devices automatically deliver the most effective format (e.g Dolby Digital vs. 2 channel PCM) for the A/V receiver that it is connected to - eliminating the need for the consumer to scroll through all the audio format options to guess what is best and properly
supported.
Q. What is the life expectancy of HDMI?
HDMI is an evolving standard and changes to meet the needs of the market. HDMI has capacity to spare, and can incorporate new technology advancements and capabilities long into the foreseeable future.
Q. How can a consumer identify which HDMI products support a specific feature, such as DVD Audio or Deep Color?
The key for consumers to remember is that HDMI has consistently enabled a variety of the most innovative new technologies (whether they be DVD Audio, SACD, 1080p/60, etc.). However, in many cases, it is up to each manufacturer to choose which features to implement in any given product. The manufacturer can thus use its knowledge of the market to choose the mix of features that makes sense for its customers. So, customers must choose devices that have the features that they want (instead of focusing on which version of HDMI is implemented by the device.). Consumers interested in confirming whether a particular consumer electronics product supports DVD-Audio or any other feature over HDMI are urged to review users’ manuals and product reviews and check with manufacturers directly.
As technology evolves, so does HDMI via its specifications versions. From the initial Version 1.0 (released in Year 2002), Version 1.3 is the newest specifications version, as explained on HDMI.org:
Q. What’s new in the HDMI 1.3 Specification?
Higher speed: Although all previous versions of HDMI have had more than enough bandwidth to support all current HDTV formats, HDMI 1.3 increases its single-link bandwidth to 340 MHz (10.2 Gbps) to support the demands of future HD display devices, such as higher resolutions, Deep Color and high frame rates. In addition, built into the HDMI 1.3 specification is the technical foundation that will let future versions of HDMI reach significantly higher speeds.
Deep Color: 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, for stunning rendering of over one billion colors in unprecedented detail.
Broader color space: HDMI 1.3 adds support for “x.v.Color™” (which is the consumer name describing the IEC 61966-2-4 xvYCC color standard), which removes current color space limitations and enables the display of any color viewable by the human eye.
New mini connector: With small portable devices such as HD camcorders and still cameras demanding seamless connectivity to HDTVs, HDMI 1.3 offers a new, smaller form factor connector option.
Lip Sync: Because consumer electronics devices are using increasingly complex digital signal processing to enhance the clarity and detail of the content, synchronization of video and audio in user devices has become a greater challenge and could potentially require complex end-user adjustments. HDMI 1.3 incorporates automatic audio synching capabilities that allows devices to perform this synchronization automatically with total accuracy.
New HD lossless audio formats: In addition to HDMI’s current ability to support high-bandwidth uncompressed digital audio and all currently-available compressed formats (such as Dolby® Digital and DTS®), HDMI 1.3 adds additional support for new lossless compressed digital audio formats Dolby TrueHD and DTS-HD Master Audio™.