The Evolution of Display Connectors
Display connections are evolving to keep up with new video technology and data rates. See what lies ahead for the future.
Chances are, you have a shoebox filled with a bunch of obsolete connectors collecting dust in your garage, or worse, your parents’ house. Each of these cables and display connectors can only fulfill one specific connection. You can’t mix a VGA cable with a tri-colored composite cord and expect it to work; the connections look and act differently from each other. This was the norm for years.
Today, the trend is moving toward fewer display connectors that handle more. This will be great news for your parents, who will bug you a little less about clearing out those ratty shoeboxes. They’ll still bug you, just about other stuff.
Connectors now are able to handle multiple signal formats, so they can carry video, audio, and data information while often being able to charge the connected device. This’ll be familiar to anyone who’s got a smartphone, and in fact, this connectivity trend is being driven by consumer devices like advanced phones and tablets. Compare this to a decade ago, where connections were driven by advances and needs of professional equipment.
The interfaces through which we connect our devices are getting smaller, denser, and faster, much like the phones themselves, now sporting fewer ports. The interfaces can make decisions about display resolutions, audio formats, Ethernet connectivity, and can receive and send control signals, so you don’t have to sweat the details. All of these interfaces use Extended Display Identification Data which allows your video card to configure itself automatically. This is what makes your display rotate to landscape mode when you plug in your phone to display content on a TV. What’s more, wireless connections are also right around the corner.
Thunderbolt is a great example of this technology, as is Mobile High-Definition Link (MHL) and DockPort, a USB connection over DisplayPort. MHL, a smaller version of HDMI carrying signal over Micro USB, can be used for a wide variety of applications, including using the phone as a game controller to replace standard hand-held ones. MHL can also be used in a phone-docking scenario to operate as a full-fledged computer. Other models that turn phones into tablets exist as well.
Certain types of DisplayPort utilizing USB 3.0 have built-in chips that enable the interface to configure automatically to the connected system. The cables are also symmetrical so it doesn’t matter which way you plug it in. You’ve seen this on more modern iPhone chargers and Apple’s display connector.
A Look Into The Future
All this shouldn’t come as a shock to anyone who owns one or more of these devices. The problem is the looming inevitability of 4k and later, 8k footage, which will put an intense strain on these interfaces.
4k video will become standard on the next generations of smart phones, so this issue is about to come to a head. Models released by LG, Sony and Samsung will all utilize playback through MHL and will come equipped with 13 megapixel cameras. It’s not just about servicing a greater array of pixels, though. Any developments in refresh rates, dynamic range, and color gamut will affect how much information needs to be pushed through these multi-purpose connectors.
Let’s take a look at the two most common connectors, HDMI and DisplayPort, to see how they fare. HDMI can carry 4k video at 60p but is limited to 8-bit color only, according to the HDMI 1.4 and 2.0 specs. At higher formats, we’ll encounter speed problems in the actual connector portion of the signal chain.
DisplayPort 1.2 is robust enough to handle 10-bit color with a 4k signal at 60p, running at a data rate of 21.6 Gb/s. DisplayPort 1.3, announced in September this year, will carry a maximum data rate of 32.4 Gb/s, utilizing the device’s four separate lanes running at 8.1 Gb/s each. It’s almost twice as fast as HDMI.
Helping DisplayPort achieve this is something called Display Stream Compression. As the name suggests, the technology condenses information packets coming to the monitor from the video card. The standard would support an 8k stream, although at a lower color space of 4:2:0. Once the video signal itself is taken care of, there would still be a fair amount of room to pass other devices such as Thunderbolt, USB and Ethernet connectivity through the connection.
This gives us some ammunition when confronted with claims that a manufacturer’s products are “UltraHD ready.” Be sure to ask which interface is making the connection happen, as there are large differences between the current states of HDMI and DisplayPort technology. Many TVs contain HDMI but they may be an older specification that cannot carry as robust a signal.
High dynamic range is something we’ll be looking for aside from just having large image support. As more entertainment gets streamed from what are essentially computers tuned to RGB color spaces, the throughput to display these images also demands more. It’s increasingly important to develop the specs properly to accommodate the highest quality possible.