Digital Visual Interface: Difference between revisions

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{{Infobox connector

|name=Digital Visual Interface (DVI)

|type=Digital computer video connector

|logo= [[File:DVIDVI_Logo.pngsvg|150pxframeless|class=skin-invert|upright=0.7]]

|image= [[File:Dvi-cable.jpg|150px]]

|caption=A [[Gender of connectors and fasteners|male]] DVI-D (single link) connector

|designer=[[Digital Display Working Group]]

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|width=

|height=

|video_signal=Digital video stream:<br />Single link: {{resx|1920&nbsp;×&nbsp;1200}} ([[WUXGA]]) &nbsp;@ 60&nbsp;Hz or {{resx|2560 × 1600}} ([[WQXGA]])&nbsp;@ 30&nbsp;Hz <br />Dual link: {{resx|2560&nbsp;×&nbsp;1600}} ([[WQXGA]]) &nbsp;@ 60&nbsp;Hz or {{resx|3840 × 2400}} ([[WQUXGA]])&nbsp;@ 30&nbsp;Hz <br />Analog video stream: {{resx|1920&nbsp;×&nbsp;1200}} ([[WUXGA]]) &nbsp;@ 60&nbsp;Hz

|data_bit_width=

|data_bandwidth=(Single link) 3.96&nbsp;Gbit/s <br />(Dual link) 7.92&nbsp;Gbit/s

|Max Distance={{convert|15|ft|m|abbr=on}} (extendible with powered amplifier).

|data_devices=1

|data_style=3 × [[Transition Minimized Differential Signaling|transition minimized differential signaling]] data and clock

|cable=

|physical_connector=

|num_pins=DVI-D Single Link: 19<br />DVI-D Dual Link: 25<br />DVI-I Single Link: 23<br />DVI-I Dual Link: 29<br />DVI-A: 11<br />DVI-M1-DA: 35

|pinout_image=[[File:DVI Connector Pinout.svg|300px]]

|pinout_caption=A female DVI-I socket from the front

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}}

'''Digital Visual Interface''' ('''DVI''') is a [[video display interface]] developed by the [[Digital Display Working Group]] (DDWG). The [[Digital data|digital]] interface is used to connect a video source, such as a [[video display controller]], to a [[display device]], such as a [[computer monitor]]. It was developed with the intention of creating an industry standard for the transfer of [[dataUncompressed compression#Losslessvideo|uncompressed]] digital video content.

DVI devices manufactured as DVI-I have support for analog connections, and are compatible with the analog [[VGA]] interface<ref name="2000 Press Release">{{cite news|url=http://www.ddwg.org/articles.asp?id=22|title=Digital Visual Interface adoption accelerates as industry prepares for next wave of DVI-compliant products|date=February 16, 2000|publisher=DDWG, copy preserved by [[Internet Archive]]|access-date=29 March 2012|url-status=bot: unknown|archive-url=https://web.archive.org/web/20070828233809/http://www.ddwg.org/articles.asp?id=22|archive-date=28 August 2007}}</ref> by including VGA pins, while DVI-D devices are digital-only. This compatibility, along with other advantages, led to its widespread acceptance over competing digital display standards [[Plug and Display]] (P&D) and [[VESA Digital Flat Panel|Digital Flat Panel]] (DFP).<ref name="Competing standards">{{cite web|url=httphttps://www.tomshardware.com/reviews/tft-guide-part-3,117.html|title=TFT Guide Part 3 - Digital Interfaces|last=Eiden|first=Hermann|date=July 7, 1999|publisher=TomsHardware.com|access-date=29 March 2012}}</ref> Although DVI is predominantly associated with computers, it is sometimes used in other consumer electronics such as [[television set]]s and [[DVD player]]s.

==History==

An earlier attempt to promulgate an updated standard to the analog [[VGA connector]] was made by the [[Video Electronics Standards Association]] (VESA) in 1994 and 1995, with the [[VESA Enhanced Video Connector|Enhanced Video Connector]] (EVC), which was intended to consolidate cables between the computer and monitor.<ref name=VESA-stds>{{cite web |url=http://www.vesa.org:80/standards.html |title=VESA Standards |publisher=Video Electronics Standards Association |archive-url=https://web.archive.org/web/19990117080256/http://www.vesa.org:80/standards.html |archive-date=January 17, 1999 |url-status=dead}}</ref><ref name=Manchester99>{{cite report |first=Gary |last=Manchester |date=1999 |archive-url=https://web.archive.org/web/20160112151649/http://www.tu-chemnitz.de/informatik/RA/news/stack/kompendium/vortraege_99/peripherie/standards/dfp/DFPwhitepap.PDF |title=The VESA Digital Flat Panel (DFP) Standard: A White Paper |publisher=VESA Marketing Committee |url=http://www.tu-chemnitz.de/informatik/RA/news/stack/kompendium/vortraege_99/peripherie/standards/dfp/DFPwhitepap.PDF |archive-date=January 12, 2016 |url-status=dead}}</ref> EVC used a 35-pin [[Molex]] MicroCross connector and carried analog video (input and output), analog stereo audio (input and output), and data (via [[USB]] and [[FireWire]]). At the same time, with the increasing availability of digital flat-panel displays, the priority shifted to digital video transmission, which would remove the extra analog/digital conversion steps required for VGA and EVC;<ref name=DVI-whitepaper/>{{rp|5–6}} the EVC connector was reused by VESA,<ref>{{cite web |url=http://www.vesa.org:80/public/Intellectual%20Property/MolexPnD.PDF |title=Molex PnD intellectual property letter |author=Manchester, Gary |date=October 7, 1996 |archive-url=https://web.archive.org/web/20030222125034/http://www.vesa.org:80/public/Intellectual%20Property/MolexPnD.PDF |archive-date=February 22, 2003 |url-status=dead}}</ref> which released the [[VESA Plug and Display| Plug & Display (P&D)]] standard in 1997.<ref name=VESA-stds/> P&D offered single-link [[Transition-minimized differential signaling|TMDS]] digital video with, as an option, analog video output and data (USB and FireWire), using a 35-pin MicroCross connector similar to EVC; the analog audio and video input lines from EVC were repurposed to carry digital video for P&D.<ref name=DVI-whitepaper/>{{rp|4}}<ref name=VESA-P&D>{{cite web |url=http://www.vesa.org/public/PnD/pnd.pdf |archive-url=https://web.archive.org/web/20030704041337/http://www.vesa.org/public/PnD/pnd.pdf |archive-date=July 4, 2003 |url-status=dead |date=June 11, 1997 |title=VESA Plug and Display (P&D) Standard, Version 1 |publisher=Video Electronics Standards Association}}</ref>{{rp|§1.3.3}}

Because P&D was a physically large, expensive connector, a consortium of companies developed the DFP standard (1999), which was focused solely on digital video transmission using a 20-pin [[micro ribbon connector]] and omitted the analog video and data capabilities of P&D.<ref name=Manchester99/>{{rp|3}}<ref name=DVI-whitepaper>{{cite report |url=https://www.fpga4fun.com/files/WP_TMDS.pdf |title=Digital Visual Interface & TMDS Extensions |date=October 2004 |publisher=Silicon Image |access-date=31 January 2023}}</ref>{{rp|4}} DVI instead chose to strip just the data functions from P&D, using a 29-pin MicroCross connector to carry digital and analog video.<ref>{{cite web |url=https://www.molex.com/mx_upload/family/microcross_dvi/082mcdvi.pdf |title=MicroCross DVI Connector System: Digital Visual Interface Standard |publisher=Molex |date=December 2000 |access-date=31 January 2023}}</ref> Critically, DVI allows dual-link TMDS signals,<ref>{{cite web |url=https://www.mouser.com/datasheet/2/276/2/molex_dvi%20technical1-1185865.pdf |title=MicroCross DVI (Digital Visual Interface) Connector System |publisher=Molex |date=November 1999 |access-date=31 January 2023}}</ref> meaning it supports higher resolutions than the single-link P&D and DFP connectors, which led to its successful adoption as an industry standard. Compatibility of DVI with P&D and DFP is accomplished typically through passive adapters that provide appropriate physical interfaces, as all three standards use the same DDC/EDID handshaking protocols and TMDS digital video signals.<ref name=DVI1.0 >{{cite web |url=httphttps://glenwing.github.io/docs/DVI-1.0.pdf |title=Digital Visual Interface Revision 1.0 |date=2 April 1999 |publisher=Digital Display Working Group |access-date=31 January 2023}}</ref>{{rp|§1.3.7}}

DVI made its way into products starting in 1999. One of the first DVI monitors was [[Apple Inc.|Apple's]] original [[Apple Cinema Display|Cinema Display]], which launched in 1999.

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==Connector==

{{see also|Mini-DVI|Micro-DVI}}

{{Multiple image

{{Stack|[[File:DVI Connector Types.svg|thumb|181px|Female DVI connector pins (view of plug)]]|[[File:M1-DA.svg|thumb|181px|Female M1-DA connector pins (view of plug)]]}}

| image1 = DVI Connector Types.svg

[[File:Digital Visual Interface - DVI.jpg|right|thumb]]

| direction = vertical

[[File:Dvi eia- 861.jpg|thumb|right|DVI port on a Sony HD CRT TV that complies with EIA-861]]

| total_width =

[[File:Computer DVI connector.jpg|right|thumb|DVI output connector on a computer]]

| image2 = M1-DA.svg

| caption2 = Female DVI connector pins (view of plug)

}}

The DVI connector on a device is given one of three names, depending on which signals it implements:

*''DVI-I'' (integrated, combines digital and analog in the same connector; digital may be single or dual link)

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*''DVI-A'' (analog only)

Most DVI connector types—the exception is DVI-A—have pins that pass digital video signals. These come in two varieties: single link and dual link. Single link DVI employs a single transmitter with a TMDS clock up to 165&nbsp;MHz that supports resolutions up to 1920&nbsp;×&nbsp;1200 at 60&nbsp;Hz. Dual link DVI adds six pins, at the center of the connector, for a second transmitter increasing the bandwidth and supporting resolutions up to 2560&nbsp;×&nbsp;1600 at 60&nbsp;Hz.<ref>{{cite web|url=http://www.anandtech.com/show/2184/2|archive-url=https://web.archive.org/web/20100520033457/http://www.anandtech.com/show/2184/2|url-status=dead|archive-date=May 20, 2010|title=Dell 2407WFP and 3007WFP LCD Comparison|last=Walton|first=Jarred|date=March 2, 2007|publisher=AnandTech|access-date=November 7, 2013}}</ref> A connector with these additional pins is sometimes referred to as DVI-DL (dual link). Dual link should not be confused with ''[[Multi-monitor|dual display]]'' (also known as ''dual head''), which is a configuration consisting of a single computer connected to two monitors, sometimes using a [[DMS-59]] connector for two single link DVI connections.

In addition to digital, some DVI connectors also have pins that pass an analog signal, which can be used to connect an analog monitor. The analog pins are the four that surround the flat blade on a DVI-I or DVI-A connector. A [[Video Graphics Array|VGA]] monitor, for example, can be connected to a video source with DVI-I through the use of a passive adapter. Since the analog pins are directly compatible with VGA signaling, passive adapters are simple and cheap to produce, providing a cost-effective solution to support VGA on DVI. The long flat pin on a DVI-I connector is wider than the same pin on a DVI-D connector, so even if the four analog pins were manually removed, it still wouldn't be possible to connect a male DVI-I to a female DVI-D. It is possible, however, to join a male DVI-D connector with a female DVI-I connector.<ref name="A+ Study Guide book">{{cite book|last1=Docter|first1=Quentin|last2=Dulaney|first2=Emmett|last3=Skandier|first3=Toby|title=CompTIA A+ Complete Deluxe Study Guide: Exams 220-801 and 220-802|year=2012|publisher=John Wiley & Sons, Inc.|___location=Indianapolis, Indiana|isbn=978-1118324066}}</ref>

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** [[WQUXGA]] ({{resx|3840|2400}}) @ 30&nbsp;Hz with CVT-RB blanking (2 pixels per 146&nbsp;MHz TMDS clock)

[[Generalized Timing Formula]] (GTF) is a [[VESA]] standard which can easily be calculated with the [[Linux]] gtf utility. [[Coordinated Video Timings]]-Reduced Blanking (CVT-RB) is a [[VESA]] standard which offers reduced horizontal and vertical blanking for non-CRT based displays.<ref>{{cite news |url=httphttps://www.nvidia.com/object/advanced_timings.html |title=Advanced Timing and CEA/EIA-861B Timings |publisher=NVIDIA |access-date=2008-06-18}}</ref>

====Digital data encoding====

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Like other ways of transmitting video, there are two different regions: the active region, where pixel data is sent, and the control region, where synchronization signals are sent. The active region is encoded using [[transition-minimized differential signaling]], where the control region is encoded with a fixed [[8b/10b encoding]]. As the two schemes yield different 10-bit symbols, a receiver can fully differentiate between active and control regions.

When DVI was designed, most computer monitors were still of the [[cathode -ray tube]] type that require analog video synchronization signals. The timing of the digital synchronization signals matches the equivalent analog ones, so the process of transforming DVI to and from an analog signal does not require extra (high-speed) memory, expensive at the time.

[[High-bandwidth Digital Content Protection|HDCP]] is an extra layer that transforms the 10-bit symbols before transmitting. Only after correct authorization can the receiver undo the HDCP encryption. Control regions are not encrypted in order to let the receiver know when the active region starts.

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* HDMI sources differentiate between legacy DVI displays and HDMI-capable displays by reading the display's [[EDID]] block.

To promote interoperability between DVI-D and HDMI devices, HDMI source components and displays support DVI-D signallingsignaling. For example, an HDMI display can be driven by a DVI-D source because HDMI and DVI-D both define an overlapping minimum set of supported resolutions and frame buffer formats.

Some DVI-D sources use non-standard extensions to output HDMI signals including audio (e.g. [[Radeon R600|ATI 3000-series]] and [[GeForce 200 Seriesseries|NVIDIA GTX 200-series]]).<ref name="HDMI2006SpecsAppC">{{cite news |title=HDMI Specification 1.3a Appendix C |publisher=HDMI Licensing, LLC. |url=httphttps://www.hdmi.org |format=PDF |date=2006-11-10 |access-date=2009-11-18}}</ref> Some multimedia displays use a DVI to HDMI adapter to input the HDMI signal with audio. Exact capabilities vary by video card specifications.

In the reverse scenario, a DVI display that lacks optional support for [[High-bandwidth Digital Content Protection|HDCP]] might be unable to display protected content even though it is otherwise compatible with the HDMI source. Features specific to HDMI such as remote control, audio transport, xvYCC and deep color are not usable in devices that support only DVI signals. HDCP compatibility between source and destination devices is subject to manufacturer specifications for each device.