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First there was VGA, Video (or Component), S-VHS and Scart connectors. All of which use analog signals. Analog signals means that we don’t need any kind of computer to process images (and sound). All we need is old-fashioned electronics or even just a piece of paper and a needle. Today when “everything” has gone digital we have got two new standards called DVI and HDMI.
Though HDMI is the new all-round standard of connecting Computers and TV (and soon every gadget and appliance ) you will still come across DVI. Especially when connecting your computer to your flat screen monitor, TV or Projector.
DVI comes in several flavours, DVI-A, DVI-D, DVI-I and M1-DA. But which is what ?
The short story is that DVI is the predecessor of HDMI, and the main difference is that the HDMI signal carries Audio as well as Video, where as the DVI signal is mute.
The Letters A, D and I denotes different technologies. DVI-I is a connector that is compatible with both DVI-A and DVI-D (which are not compatible). DVI-A is largely a computer format. DVI-D is commonly used on all other home electronics.
- DVI-A = Analog
- DVI-D = Digital
- DVI-I = Integrated (Both A and D)
- M1-DA = Integrated (A, D, I and USB)
Another term that comes into play is Dual Link, which is what makes DVI support high-resolution displays. This is sometimes called DVI-DL. To give you an idea of the differences, here is the short story:
A Single Link DVI signal is somewhat equal to the analog video signal. The signal quality is only limited by the transmission rate in the copper (transfer rate of maximum 165 MHz). Single Link Signal gives you a maximum resolution of 2098 × 1311 pixels (16:10) and 1915 × 1436 pixels (4:3). Which for most products are more than enough. For components requiring larger bandwidth (exceeding 165 MHz) a second set of cables are provided to send twice the information. Much like Progressive vs Interlaced singals (Read About that here)
Differences in the connectors
As mentioned earlier the different DVI technologies are not directly compatible. To avoid user errors, the connectors are slightly different, making the incompatible devices impossible to connect. Some connectors can only be connected one way (DVI-D Male to DVI-I Female, not DVI-I Male to a DVI-D Female). Idiot-Proof as we say over here.
High-bandwidth Digital Content Protection (HDCP)
In the old days there were analog copy protection capabilities in VHS recorders, making it (almost) impossible to copy a commercial VHS to a private one. Same thing today. Some Equipment have extra HDCP connectors; that send an encrypted signal using the HDCP protocol for copy protection.
Computers with DVI video connectors can use many DVI-equipped HDTV sets as a display, but only computers whose graphics systems support High-bandwidth Digital Content Protection are able to play content that requires digital rights management unless of course the DRM scheme is broken and the DRM break is implemented.
Short story over
I realize that there are much more to this topic than the above, and I welcome your input in the Comment section below.
About Thomas
Computer geek from the age of 7, which amounts to 30 years of computer experience. From the early days (when every computer company had their own OS) of DOS, Windows 1.0 through Seven...
It’s ok… DVI is dying and being replaced by Displayport (don’t worry, it’s backward compatible to DVI with a simple, small, inexpensive adapter)
Displayport (DP for short), is essentially DVI, with audio support (can be optional). the plug was designed to support more plug-in and outs, easier to plug-in, snap/clip system for a better hold (an issue with HDMi) and smaller. This is makes it ideal for laptops as well.
Displayport can also be very easily converted with a simple, inexpensive adapter to HDMI (HDMi is based on displayport)
HDMi is essentially Displayport (pin layout different), with carrying audio set to be non-optional, and scarp any important on maintaining color accuracy (designed for TV’s, and not computer monitors, where you are up-close to the screen), and add a large royalty fee to it. Today, HDMi has additional feature separating itself to DVI and Displayport, such as networking.
As for Displayport, the new standard (DP 1.2, currently nothing uses it), supports daisy chaining, and carries USB. This means, that USB is carried on the same wire, and you can attach up to 6 monitor with 1 plug on your computer. DP 1.2 cables and ports are identical to the older versions and is perfectly backward compatible.
Often the safest choice for a DVI Cable for a new DVI video card connecting to a DVI Monitor is a DVI-D to DVI-D “Single Link” cable. If the card and monitor are closer to “state of the art” a “Dual Link” cable may be needed. In most cases both will work. If a connection is DVI-D, and properly designed, you will not be able to plug in a DVI-I cable but should use a DVI-D cable, even if one of the devices you are connecting is DVI-I. If your monitor is older and you want to ensure that you are using the digital connection, a DVI-D cable would usually be a better choice. Those with monitors with DFP connectors would need a DVI-D to DFP cable. You cannot directly connect DVI-D or DFP to VGA, since you need an analog to digital conversion.