So last week I mentioned that HDMI was not the latest format, it was just the latest craze. So the latest type of port and connector (as of this writing) is the DisplayPort.
So, here I am at a show in Augusta, Georgia and I came across my first DisplayPort compatibility issue. Our client’s HP laptop had a DisplayPort output and the monitor had an HDMI input. Well you should have seen me running around town looking for the adapter having no clue what the port was even called. I showed them a photo or just told the sales people it looked like HDMI but one side was chopped off or 90 degrees. After my 5th store, one savvy tech person finally said “oh – you’re talking about a DisplayPort.”
Well, then I learned that Mac users are quite familiar with this term as they use a mini DisplayPort connection all the time. So once he knew what I was looking for, he easily showed me a passive DisplayPort to HDMI adapter cable which took care of the connection problem. I did get lucky though, as the DisplayPort graphics card in the laptop could recognize the monitor connection as HDMI and could output an HDMI signal. Note that I said that the cable was a passive adapter cable. It is very important to understand when a passive adapter will work and when an active adapter is needed. Hold on till next week and we will go over passive adapters and active adapters (active adapters are also referred to as converters).
So in all this confusion you’re possibly asking, “why did we need another type of port and cable?” Well, I asked the same question when the Phillips screwdriver tip was invented ─ now look at how many different types of screwdriver tips there are! But I digress, so let’s get back to the DisplayPort. In my research, one of the biggest reason I’ve found for the premiere of the DisplayPort is that it’s royalty free, whereas HDMI charges 4 cents per device. That doesn’t seem like much, but I guess if you are a manufacturer that could add up. That’s not the only reason, however.
About three years after HDMI was introduced came the DisplayPort. It was designed specifically to go from a graphics card to a monitor in the computer world where HDMI’s roots started in TVs and DVD players. Basically HDMI came from the consumer electronics world. In other words, the DisplayPort is a computer interface whereas the HDMI port is a home electronics interface. The DisplayPort was designed to replace the DVI connection while HDMI was designed to replace the Composite, RGB and S-VHS connections once TVs went digital.
These two ports have different standards and capabilities, with the DisplayPort reaching new heights in bandwidth and long distance cabling. The DisplayPort uses a packet based transmission system while HDMI and DVI use a system called TMDS, meaning Transmission Minimized Differential Signaling. The DisplayPort packet system provides a more flexible use of bandwidth. It comes in one, two, and four link versions, with increased data capacity in each version. The 1.2, or middle version, is good enough for most applications, as it easily surpasses HDMI at 17 Gigabits per second (Gbit/s); HDMI’s maximum rate is around 10.4 Gbit/s. Either way, you only need about 750 Megabytes per second for 1080P video. The DisplayPort has many other features, but that’s a much longer article than what’s practical for this blog!