High Definition Multimedia Interface [ haɪ ˌ ˌ defɪnɪʃən mʌltimi ː diə ɪntəfeɪs ] (short HDMI) is a technology developed from mid-2003 interface for full digital transmission of audio and video data in consumer electronics. Unifies existing methods, increased compared to the quality of these features and also provides a coherent concept copy protection (DRM). The latest HDMI version is 2.0, but HDMI products are no longer marked since 1 January 2012 with version numbers.
- 6.1 HDMI and resolutions above Full HD
- 7.1 HDMI standard
- 7.2 HDMI Standard with Ethernet
- 7.3 HDMI Standard Automotive
- 7.4 HDMI High Speed
- HDMI 7.5 High Speed with Ethernet
HDMI was developed by the industry for the area of privately used consumer electronics ( english home entertainment).
The HDMI Founders Hitachi, Matsushita Electric Industrial ( Panasonic, National, Quasar ), Philips, Silicon Image, Sony, Thomson and Toshiba began on 16 April 2002 together to develop the new standard AV connection HDMI. HDMI is an evolution of DVI plus backward compatible. Both use the same signal encoding TMDS. HDMI 1.0 is designed so that it has a smaller connector as DVI. It should also extend the capabilities of DVI to audio transmission, enhanced support for YCbCr, and a user-driven control function (german Consumer Electronics Control). The HDCP 1.1 (High -bandwidth Digital Content Protection), which is provided in the HDMI specification was developed by Intel. It is intended to prevent the interception of video and audio material in the connection between transmitter and receiver.
The first manufacturer who brought HDMI -enabled components to the market in late 2003, was with the Pioneer DVD players Pioneer DV- 668AV Pioneer DV and 868AVi, the DVD recorder Pioneer DVR -920 HS and the plasma TV Pioneer PDP- 434HDE and Pioneer PDP - 504HDE. Meanwhile, the HDMI standard has been expanded several times in order to meet recent demands.
Cable length and quality
From the HDMI organization more than 15 meters long cables are provided so far. Chance of lengths up to 20 meters are available that do not but work fine in all cases. There are also special cables with optical fibers that allow a length up to 100 meters. Long cables must generally better high frequency characteristics to ensure error-free data recovery in the HDMI receiver. For error-free transmission, the cable quality as well as the reception characteristics of the HDMI receiver are crucial. For cable lengths up to five meters and low-quality cables are sufficient because of the digital transmission.
A cable length of about 10 meters is expected to transmission errors, which can be reduced through high-quality cable. Whether errors, can be assessed very easy on the resulting image quality due to the TMDS encoding used in HDMI. You can see it through colored " flash " of image points (pixels) or entire rows of pixels. Noise in the traditional sense or artifacts of the analog data transmission can therefore exclude generally with HDMI, if the HDMI transmitter or the HDMI receiver, the video data resolution is not limited ( for example, 8 -bit instead of 12 -bit color component resolution in YCbCr 4:2: 2 format ).
1.3 to further increase the data rate for HDMI, two cables categories were defined with different high-frequency characteristics. A Category 1 cable can transmit pixel rates of up to 74.25 MHz, a Category 2 cable up to 340 MHz. Are HDMI 1.3, to ensure error-free transmission over longer cable, first established even the cable properties such as attenuation, signal propagation time differences, crosstalk and so on in more detail. To counteract the inevitable cable attenuation is provided in HDMI 1.3 pixel rates above 165 MHz receiver hand, a cable equalizer to boost the higher frequency signal components.
With signal repeaters (for example, in an AV receiver), the distance be doubled. For larger distances are " Extender" available that convert the signal and transmitted via fiber optic cables. With appropriate converters for a conversion to HD -SDI and back is possible, there is the advantage that HD -SDI with only one coaxial cable has BNC connectors, also can bridge long distances. The use of SDI connections has mainly for professional users, such as proven on a movie set.
Short HDMI cable to 2 meters are available for less than 7 €, and also cheap cable transmitted over the short distance, the maximum resolution ( 1080p HDMI 1.1 or 1.2) without loss. Cable for HDMI 1.2 or 1.3 must pixels frequencies to transmit up to 165 MHz and 340 MHz and need better high frequency characteristics.
By appropriate labeling of the HDMI cable to choose the right cable is facilitated by information on the type of cable.
HDMI 1.1/1.2 two connector types ( about 4.5 mm × 13/21 mm cross-section type A and type B ) are defined. For HDMI 1.3 also a small connector (type C or mini - plug, about 2.5 mm × 10.5 mm cross section) for compact devices included. In an even smaller connector HDMI 1.4 Type D (Micro -Tip) were defined. In addition, the plug - type E is defined in the HDMI 1.4 specifications, but not to use comes with 1.4 cables, but only for HDMI standard automotive cables.
Type A, C and D are based on a single-link connection, are in the three TMDS signal line pairs available, Type B permitted through a dual-link connection with six TMDS signal line pairs double the data rate.
Assignment of the most common (device ) jack Type A ( contact side ) and ( cable ) Connector type A ( soldering side ) and the usual tablet computers Micro HDMI Type D connections
Processed with its high data transfer rate HDMI all of today's digital video and audio formats for consumer electronics. HDMI 1.2 transmits audio data up to frequencies of 192 kHz with word sizes of up to 24 bits to up to eight channels. For HDMI 1.3 were classified as new audio formats Dolby Digital Plus and Dolby TrueHD included. The maximum pixel frequency for video data with single-link is for HDMI 1.2 at 165 Mpixel / s ( type A) and for HDMI 1.3 at 340 Mpixel / s (type A / C). This can not only transfer all today introduced in the consumer electronics video and audio formats including HDTV ( up to the highest resolution of 1080p ) with no loss of quality, but also other image resolutions up to 2560 × 1600p75. With HDMI 1.3 also support for higher color depths was added. So far, only 24-bit ( RGB 4:4:4, YCbCr 4:4:4, YCbCr 4:2:2 ), 30 bit and 36 bit were (YCbCr 4:2:2) possible. The higher data rate for HDMI 1.3 allows color depth of 30 bit, 36 bit and 48 bit with 10/12/16 bits per color component (RGB 4:4:4, YCbCr 4:4:4 ). HDMI 1.3 in addition to the previous formats SMPTE 170M/ITU-R BT.601 and ITU -R BT.709 -5 supports the new xvYCC color space model, which is defined in the standard IEC 61966-2-4, and thus enables a very large color space to improve the color reproduction. These special color space metadata are transferred.
Data transfer rates
HDMI 1.2 and DVI provides high data transfer rates of up to 3.96 Gbit / s ( Type A 19 -pin) or 7.92 Gbit / s ( Type B, 29 pin, not common in consumer electronics ). HDMI 1.3 and 1.4 up to 8.16 Gbit / s ( type A and C, 19 -pin) are possible.
The specification versions that are listed in the following table describing the organization of the HDMI specifications, which are placed on HDMI verified devices. New specifications are published at irregular intervals. This includes specifications of properties of the terminals, cable characteristics and submitted signals and their function.
The cables were previously in the same way as the specification numbered versions (eg 1.2 specification led to new cables with the version number 1.2 ) because a newer number meant a more efficient cables. As in the newer specifications were (from 1.4) does not define a better cable, the cable but were equipped in trade with the newer ones and this suggested a higher performance, the HDMI organization decided to define new names for the cable (see section HDMI cable types and properties).
HDMI and resolutions above Full HD
As of version 1.3, HDMI is able to control resolutions above 1920 × 1080 (HDTV 1080p60 or Full HD) and 1920 × 1200. With the advent of monitors that offer with a screen diagonal of 27 inches ( 598 mm × 336 mm ) resolutions of 2560 × 1440, the driving of these monitors with a native resolution over HDMI is possible. Both newer graphics cards and on-board graphics chipsets as well as the receiving circuits in the monitors are capable of doing.
The existing problem is that the monitors report a maximum resolution of 1920 × 1080 and therefore offer the graphics card driver no higher resolutions. Become a modified Windows driver used or graphics driver used ( modeline " 2560x1440 @ 60 " 241,500 2560 2608 2640 2720 1440 1443 1448 1481 hsync - vsync ) allow the freely programmable video timing, the use of the native resolution works fine.
This problem occurs especially in the field of notebooks ( with D -Sub and HDMI output, but no DVI dual link and DisplayPort output ), as it often is the only way to control these monitors properly and it is a pure software or firmware problem. Therefore, same is true for the much rarer 30 - inch monitors with a resolution of 2560 × 1600 pixels.
Ultra HDTV is supported by HDMI version 2.0 or higher.
HDMI cable types and properties
Since about November 2010 HDMI cables are binding divided into five classifications: same time, a ban on the sale of HDMI cables with the old HDMI version numbers with one year's notice was issued in November 2011. Since 1 January 2012, the specification of a HDMI version number is also on devices banned and all the functions that support the interface must be enumerated, as you can pull the release number, no conclusions on the functions supported, because an interface version 1.4 does not needs to support more functions as an interface of version 1.0. This happened in the wake of the transition to the new cable names to ensure a better guidance on the cable dial. Reason for the ban are those irritating numbers that are often sprung from the marketing departments of the cable manufacturer and have given the impression that only the latest version of justice to all cable requirements. However, since, for example, HDMI 1.3 cable, the same performance characteristics as 1.4 cable only without additional HEC - line, these often enough. Therefore, a direct comparison of the new labels with the old numbers is not possible.
A comparison of the new cable names with the various HDMI specification versions is not possible because the specifications also specify requirements for devices that are not necessarily dependent on cables.
The standard cable only includes the basic services, as well as the minimum requirements, 1080i or 720p to transmit at a frequency of at least 75 MHz. The transmission is possible up to a cable length of 10 meters. The data transfer rate is at least 1.782 Gb / s and a maximum of 2.25 Gbit / s
HDMI Standard with Ethernet
Properties similar to the standard cable, but with an additional HDMI Ethernet Channel ( HEC) of a network connection.
As these cables are suited for HEC, although Ethernet already reserved wires are used, but these have to be twisted in cable in order to reduce interference.
HDMI Standard Automotive
Standard HDMI cable with plug type E, which are only used in the automotive industry. These cables were developed specifically for the requirements in the automotive field, for example, to resist temperature changes and vibrations. The resolution is limited to 720p/1080i.
HDMI High Speed
These cables transfer Full HD 3D and Deep Color up to 1080p at a frequency of at least 340 MHz. The maximum transferable gross data rate is 10.2 Gb / s ( 3 x 340 MHz TMDS links x 10 bits per data word). After deduction of the overhead of 8b10b encoding used results in a net data rate of up to 8.16 Gbit / s In addition, 4K2K is possible. With high-speed HDMI cables up to a distance of 7.50 meters cable length is possible.
HDMI High Speed with Ethernet
How High Speed HDMI cable, but with an extra HDMI Ethernet Channel ( HEC) for a network connection.
Remote control functions
With HDMI it is optionally possible to use remote control functions. This base features several HDMI cables connected components can be controlled by a single remote control. The protocol used is called Consumer Electronics Control ( CEC) and was derived from the European standard analog AV Link.
HDMI is backward- compatible with DVI -D ( Digital Visual Interface) and DVI-I, the. Pending the introduction of HDMI single widespread digital interface for video in the home Professional users operate the other hand, since the late 1990s, the SDI interface. The HDCP copy protection is given if the video material manufacturers activated (eg in CSS encoded DVDs ) via control bits and then requires according to regulations at both interfaces, a hardware chip that encodes the video signal to the digital output line and then decodes the display. Without HDCP chip otherwise the screen remains blank (or only shows colored noise ), also can be used in so-called "HD ready" devices yet any detected analog output interface ( progressive component signal YPbPr) are affected (eg standard definition only ) to prevent high-quality copies. The DVI interface to HDCP -enabled newer video devices (eg DVD players ) therefore is not compatible with DVI interfaces in the computer field, unless on these components HDCP is implemented (which as of January 2009 with many PC Flat panel displays the case). In such devices that have a DVI input with HDCP support, it is possible to output with a HDMI to DVI adapter from the copy protected video signal. Also audio can be output and received via DVI, the audio signal is also transmitted digitally with the image signal as HDMI in TMDS signal.
Meanwhile graphics cards with HDMI interface on the market, which also include an HD audio chip to output directly through the HDMI output of the graphics card and audio signals can. This audio chip appears in the operating system as a second sound card and can be used as such. This makes it possible to connect suitably equipped computer directly with flat screen TV or HD projector. This makes the possibilities of a home cinema with a home theater PC even more interesting.
On 23 August 2005 HDMI 1.2 was officially adopted, which is fully backward compatible with HDMI 1.0/1.1. As an extension of a 1 -bit audio stream was taken as found for example in the SACD application. In addition, some new secondary video formats were added to support higher refresh rates, for example, to 240 Hz and above the usual PC video formats.
- A problem has arisen when connecting different brands of playback devices and screens, because the industry is the digital image level formats "DVI - PC" or " DVI video " has ( includes HDMI the same video format as Digital Visual Interface connectors) often implemented in their devices without thinking at a later Umstellmöglichkeit. The difference: While computers (DVI- PC) range, the brightness values of Y = 0 to Y = 255, Home Electronics ( DVI Video) an area reserved under or above the black and white levels ( the specification ITU- 601R defined black with Y = 16 and Y = 235 White ). Only some video projectors and flat panel displays can be made by setting menu between PC level or RGB ( "extended " / " expanded " ) and video - Level or YCbCr ("standard " / " normal") shall be reversed. Black is either too light, or lower brightness areas are swallowed (ie, dark areas are all black ), the white level is not maximal or is overridden, all depending on the unit combination. Only if by chance the same interpretation of the digital video level in both devices agrees with the contrast range of the HDMI input that can not be changed by brightness or contrast controls.
- Another problem has arisen with the new sound formats such as DTS -HD or Dolby TrueHD: Frequently grind flat screen TV, the HDMI audio signal simply via S / PDIF and make it so for sound receivers available. The data rate currently is not sufficient to transfer the new HD sound formats 1:1. DTS - HD here the DTS core is output with ≈ 1.5 Mbps. In other formats, a real-time down-mix of about 6 Mbit / s to 1.5 Mbit / s is provided, so that S / PDIF, a signal can be output. Basically, however, goes hand in hand with correspondingly lower sound quality. In multi-channel LPCM only a AC3/DTS-Live-Encoder remedy would bring.
Alternative multimedia interfaces
- DVI ( Digital Visual Interface)
- SDI (Serial Digital Interface)
- UDI (Unified Display Interface )