What is HDMI

Is a kind of full digital image and sound transmission of audio and video signalinterface, can send uncompressed. HDMI can be used for set top box, DVD player,personal computer, video game console, integrated amplifier, digital audio andtelevision equipment. HDMI can also send the audio and video signal, the audio and video signals using the same cable, which greatly simplifies the installation difficulty system line. HDMI was designed to replace the analog video transmission interfacesuch as SCART or RCA of the old terminal. It supports all kinds of TV and computerimage formats, including SDTV, HDTV video screen, plus multi-channel digital audio.In the transmission, various video data will be hdmi extension cable transceiver chip to "transmission minimized differential signal" (TMDS) technology is encoded into data packets. At the beginning of the formulation of specifications when the maximum pixel transmissionrate of 165Mpx/sec, enough to support the 1080p image quality of 60 frames per second picture, or the resolution of the UXGA (1600x1200); later in the HDMI 1.3 specification amplification for 340Mpx/ seconds, to meet the needs of the futurepossible. vga extension cable also supports non transmitting compressed digital audio (8 channelsampling rate of 192kHz, 24bits/sample data length), as well as any compressed audio stream such as Dolby Digital or DTS DSD signal, 1bit also support SACD by the use of 8 channel. In the HDMI 1.3 specification, adding ultra high data volume of non compressed audio stream such as Dolby TrueHD and DTS-HD support. Type Astandard HDMI connector 19 pin connector, Type B another support higher resolutionis defined, but there is still no manufacturers using the Type B connector. Type Bconnection has 29 pins, video channel to allow its transmission expansion to meet future high quality requirements, such as WQSXGA (3200x2048). Type A HDMI can be down compatible in the use of nowadays most display and graphics of Single-linkDVI-D or DVI-I interface (but does not support DVI-A), the said signal source using DVI-D interface can drive vga cable  screen by converting the line, but the conversionscheme does not support audio sending and remote control function. In addition, if there is no HDCP certification DVI screen will not be able to watch the video data withHDCP encryption to protect the output from the HDMI. (all HDMI screen all support HDCP, but most of the DVI interface display does not support HDCP.) Type B HDMI connector will also be downward compatible with Dual-link DVI interface.

The advantages of HDMI

HDMI advantages comparing with the analog video interface existing such ascomposite, S-Video and video component:

1, quality:HDMI  is a digital interface, since all of the simulated connection (such ascomponent video or S-video) requirements in the converted from analog to digitalwithout loss, so it can provide the best video quality. This difference in the higherresolution, such as 1080p is particularly evident. Digital video than component video is more clear, eliminate the discovery component video in softness and tailing phenomenon. Such as text of this kind of small, high contrast detail the difference will be developed to the extreme.

2, ease of use: HDMI in the single cable integrated video and multi-channel audio,eliminating the use of the A/V system in the multi cable cost, complexity and chaos.This is particularly useful in upgrading or add equipment.

3, Gao Zhineng:HDMI supports video source (such as a DVD player) and bidirectional communication between DTV, the realization of new functions, such as automatic configuration and a key player. By using HDMI, equipment for the connection of the automatic transmission display the most efficient format (such as 480p vs 720p, 16:9 vs 4:3)? From the consumer need to scroll all the formatting options, to guess the best viewing format trouble.

4, high definition content ready: support for HDCP HDMI devices to access highdefinition content high, we bring some comfort to me. HD-DVD and Blu-ray have for today's high definition movie delayed starting image resisting marking (also calledcontent protection mark), to help minimize the potential problems caused by the conversion, but is expected to start this tag within a few years, means that the futureof high definition movie will not pass not protected interface (such as analog element)broadcast in high definition.

The application of HDMI

HDMI is the first in 2002, in order to obtain higher quality video and digital audiosystem, in order to meet the needs of users. Many different TV, computer and electronic products manufacturers have adopted the HDMI specification. These standards were introduced in the electronic manufacturing enterprises association,with the major music and film distribution firm cooperation. HDMI uses the EIA/CEA-861 standard definition video waveform and format, the auxiliary data, transport ofcompressed and uncompressed audio, audio and LPCM.

There are two different types of lead in the market, namely the class 1 and 2. These categories only applies to version 1.3 and higher, this is in 2008. Category 1 cableunder standard HDMI cable labels, and suitable for video and audio signal transmission 720p or 1080i. In the second types of information are also consideredspeed cues, and can make video and audio signal, 720p and 1080i and 1600P.Classification of two HDMI hdmi to dvi cable is guaranteed to work with more than 16 foot cable is the only type.

Because the signal attenuation, long lead should have certain limit. Cabletransmission of digital signal is too long is very weak, resulting in image flicker on the screen. The use of HDMI extender, equalizer or repeaters, can avoid the loss of signal problems. These devices can be used for cable connected to each other, thus extending the length of the hdmi to rca cable , and not lose the signal strength. The maximum length of the cable can be used to determined the category. In five, category six cablecan increase the total cable length of 164 feet. If the extended use is based on theoptical fiber, the total length of the cable is increased to 328 feet.

The difference between the cable and the optical cable

Cable: when the unit will sound signal into electrical signal through the line after the transfer to the switch, and then by the switch by lines will signal directly to the othertelephone answering a call, the process of transmission lines is cable. The inside of the cable is mainly copper core wire. The diameter of the core wire with 0.32mm,0.4mm and 0.5mm points, the greater the diameter of communication ability is stronger; and according to the core line number, are: 5, 10, 20 of of of, 50, 100, 200of of of and so on, here refers to the maximum number of users log cable hold and press; packing, this I do not know. Cable: the volume, weight, communication ability,can only be used for short distance communication. Cable: when the unit will soundsignal into electrical signal through the line after the transfer to the switch, and thenby the switch will this electrical signal is transmitted to the photoelectric conversiondevice (converts electrical signals into light signals) to another photoelectric conversion device by lines (convert optical signals into electrical signals), then toswitching equipment, to the other telephone answering. In between the twophotoelectric conversion device is the optical cable line. With that number it only core line of the points, the core line number: 4, 6, 8, 12 and so on. Cable: its volume, small weight, low cost, large communication capacity, the advantages of good communication. Because of many factors, it is only used for long distance and from point to point (i.e. two switching) communication between. The difference between them is: inside the cable copper core wires; cables inside the glass fiber. Optical fibercommunication cable is a certain amount in a certain way to form the cable core, asheath of outsourcing, and some also covered the outer protective layer, with a line of communication to achieve the optical signal transmission. Once successively inShanghai, Beijing, Wuhan and other places to carry out field test. Soon after in thelocal telephone network as interoffice trunk trial, after 1984, gradually for the long-distance lines, and start using single-mode fiber. Communication vga to hdmi cable with a transmission capacity greater than copper wire cable, relay section of long distance,small volume, light weight, no electromagnetic interference, since the cable transmission line shaft after 1976 has developed into the trunk, intracity relay,offshore and transoceanic submarine communication and local area network, private network and so on, and began to develop the city user loop distribution network field,provide transmission lines for fiber to the home, width generation integrated service digital network. Cables are usually similar to the rope hdmi to rca cable by a few or several sets of wires [Each] and twisted by at least two mutually insulated wire, between each group,and often revolve around a central twisted, the entire outer covering layer of breadwith highly insulated submarine cable; specified first: distinguish the material. Cablewith metal material (mostly copper, aluminum) for conductors; cable with glass fiber as the conductor. Second: is there a difference transmission signal. Cable transmission is a signal. Optical fiber transmission is optical signal. Third: there is adifference between the scope of application. The cables are used for energytransmission and low data transmission of information (such as telephone). Cableused for data transmission.