DIGITAL VISUAL INTERFACE

INTRODUCTION:

DVI is an acronym for Digital Visual Interface and carries uncompressed digital video date to a display. When these cables first came on the market in 1999, they were primarily used for connecting the computer monitor to the PC, but today, these cables are now used for television set connection especially flat screen TVs.

Digital Visual Interface is a video interface standard

designed to maximize the visual quality of digital display devices

such as flat panel LCD computer displays and digital projectors.

It is developed by an industry consortium, the Digital

Display Working Group (DDWG).

It is designed for carrying uncompressed digital video data

to a display.

Block Diagram of DVI system

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EXISTING SYSTEMS

HDMI is an acronym for high definition multimedia interface. This is a newer form of cable introduced in 2002 to coincide with the introduction of high definition television.

HDMI connector

The HDMI cable is an all-digital video interface cable that can transmit uncompressed streams of data. This cable carries both audio and video signals.

It's a medium-sized 19-pin connection that's becoming standard on a range of audio-visual products. For TV, DVD and game playing it takes over the function of the Europe-wide SCART socket by carrying sound and pictures simultaneously. Unlike the SCART, HDMI uses digital signals throughout. It can also replace separate digital audio connections, such as optical or coaxial leads. In theory this makes an Audio Visual system simpler to link together.

The TV will also need an HDMI input - preferably more than one to allow for additional items at a later date. If there are not enough HDMI inputs, switch-boxes are available for connecting more than one HDMI product and swapping between them. One, two or more HDMI inputs are now standard on most new flat-panel LCD and plasma TVs as well as rear-projection TVs and standalone video projectors.

HDMI Input

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DISADVANTAGES OF DVI

Requires a separate audio cable, unlike HDMI. DVI-A and DVI-D devices aren't compatible.

Low availability of models with digital interfaces.

Requires graphic board with digital output.

PROPOSED SYSTEMS

Higher spectral efficiency will be a key feature of any acceptable radio interface beyond 3G. A promising approach for the downlink, is to adaptively multiplex user data onto an OFDM transmission scheme. This will minimize interference between users within a cell and efficiently allows users to share the total bandwidth. In such a system, spectral efficiency can be improved by allocating the time-frequency resources based on throughput requirements, quality of service constraints and the channel qualities of each user.

Proposed successors

IEEE 1394 is proposed by High Definition Audio-Video Network Alliance (HANA Alliance) for all cabling needs, including video, over CoAx and/or 1394 cable as a combined data stream.

High-Definition Multimedia Interface (HDMI), a forward-compatible standard, that also includes digital audio transmission.

Unified Display Interface (UDI) was proposed by Intel to replace both DVI and HDMI, but was deprecated in favor of DisplayPort.

DisplayPort is a license-free standard proposed by VESA to succeed DVI, which also has DRM capabilities.

ADVANTAGES OF DVI

Mainly that it is digital. With VGA, the computer makes a digital video output, converts it to analogue to go down the VGA cable and then the monitor converts it back to digital. With DVI, it's digital all the way, so higher quality.

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I think DVI also support higher resolutions (up to about 1900xsomething I think) and sends other information down the cable which means that you dont have to adjust your monitor.

I think VGA is being scrapped soon, becuase almost all new monitors are DFP (LCD) and use DVI instead.

Lossless Transmission as no conversion is required.

Provides support for much higher data rates.

Requires only one cable to transfer RGB signal.

Display technology independence.

FEATURES

DVI provides high speed digital connection.DVI provides a digital interface between a personal computing device and display device.Digital and Analog support in single connector.

DVI enables content to remain in lossless digital domain from creation to

consumption.

DVI is display technology independence.

DVI features plug and play through hot plug detection

High-speed TMDS level shifting Converts four lanes of low-swing AC-coupled differential input signals to DVI and

HDMI compliant open-drain current-steering differential output signals TMDS level shifting operation up to 2.25 Gbit/s per lane (225 MHz character

clock) Integrated 50 Ohm termination resistors for self-biasing differential inputs Back-current safe outputs to disallow current when device power is off and

monitor is on Disable feature to turn off TMDS inputs and outputs and to enter low-power state

DDC level shifting Integrated DDC level shifting (3.3 V source to 5 V sink side) 0 Hz to 400 kHz clock frequency

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Back-power safe to disallow backdrive current when power is off or when DDC is not enabled

MAIN PURPOSE

1.TELEPHONE

Telephone networks have been evolving for more than a century. Traditional voice

communication is expected to be enhanced and eventually replaced by visual communication in

the future. This paper addresses two key elements in digital visual communication: video

compression and access link technology. Remarkable advances in video compression have come

about in just the past few years, especially through international standardization endeavors. For

video compression, we review existing and ongoing standards including JPEG, H.261,

MPEG1/2, H.26P, MPEG4, and North American HDTV. These standards cover a broad

spectrum of applications and are considered the main standards to be used in visual

communications. An overview of access technology for POTS, ISDN, HDSL, ADSL, and ATM

broadband networks is given. Video coding standards that can be used to transport visual

information over these networks are described. Possible future developments for access

technology are also discussed.

2.DIGITAL AUDIO TRANSMISSION

In general, a system and method for routing audio over a Digital Visual Interface (DVI) link is described herein. In one embodiment, the system comprises a Digital Audio Interface (DAI) transmitter and a DAI receiver. Coupled to a fourth channel of the DVI link that transmis a pixel-rate clock signal, the DAI transmitter modulates the pixel-rate clock signal by input digital audio. The DAI transmitter sends the modulated clock signal to the DAI receiver. The DAI receiver recovers the digital audio from the modulated pixel-rate clock signal.

LIMITATION OF DVI

Maximum length of cable can be used is 5 meters. Audio signal cannot be

sent with video signal. DVI connector is bulky. Electro-Magnetic

Interference will occur due to clock signal.

CONCLUSION

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The DVI interface has gained industry wide acceptance and is considered the industry standard digital graphics interface. It offers the right combination of versatility and functionality. DVI can be used to deliver single or dual-link digital video to a display device while supporting legacy analog devices. Leading market research firms are forecasting dramatic rises in sales of digital display devices, which will eventually surpass sales of the current analog display devices. Market surveys indicate that over 50% of the displays sold in Japan today, are digital. DVI is also spreading into the consumer market. There are plans to add the DVI connector to HDTV sets, Set-top boxes, DSS receivers and HD-DVD players. DVI is poised to replace the analog VGA connector to become the single, universal display interface.

Bibliography“Understanding Direct Digital Technology” Extron Electronicshttp://www.extron.com/download/files/appbrochure/directdigital.pdfChang, Luke and Goodart, Joe “Digital Visual Interface” Dell Computer Corporationhttp://www.dell.com/us/en/arm/topics/vectors_2000-dvi.htm“Multimedia/Panel Displays,” PC Tech Guide.comhttp://www.pctechguide.com/07pan2.htm“High-bandwidth Digital Content Protection (HDCP)” Silicon Image. Inc.http://www.siimage.com/documents/SiI-WP-002-A.pdf“PanelLink A/V: The Digital Solution for HDTV” Silicon Image, Inc.http://www.siimage.com/documents/SiI-WP-003-A.pdf“Digital Video Solutions-PanelBus” Texas Instruments Inc.http://www.ti.com/sc/docs/products/msp/intrface/panelbus/market.htm

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