If you are an Integrator distributing audio and video across a facility, you may be overwhelmed by all the choices you are presented with out there in the marketplace. Whether you are doing one source to one display, one source to many displays with a distribution amp (DA) or many sources to many displays with a matrix switcher, at the end of the day you still need to get video signal from point A to point B.

For the uninitiated, the choices can be confusing, so I thought I’d give a quick breakdown of what we have found works and what is usually problematic.

HD over USB
You may have seen these devices on the market. It is a converter and software that turns your USB port into an HD video output. Please, I beg you to avoid these at all costs. Specifying one into a job will cost you time and money, and you will inevitably end up using another solution in the end.

The problem starts with throughput, and depending on the version of USB on the PC outputting the signal it may be way too low for streaming high-res imagery. The second problem is that the bus is shared by other devices like mice, etc., which don’t take a lot of bandwidth, but get assigned priority over other devices for routing through the bus.

However, the major headaches come in here: there is no HDCP; there is no EDID, so you have to define output size and resolution manually; and software is required, so hosting someone else’s laptop in this system means that they have to install the software first.

HD over IP
There are a couple of flavors of this technology. The nice thing is that they can leverage Ethernet switches to do the distribution across a network, meaning that expensive, dedicated DAS or matrix switches are not required. If doing point-to-point, you can “ditch the switch” (HD over IP companies, call me if you want to use my newly coined phrase!) and use a receiver and transmitter pair with no issues. HDCP and EDID data are transmitted.

The major plus is you gain distance over traditional baluns as you get HD to 300 feet on copper. The main drawback to most of the HD over IP solutions is that the encoding adds some compression to the signal. Most of the installations I have seen will not really suffer too much from some compression; however, for purists this is a compromise that will not be made lightly. one such HDMI over IP company relates prominently in their specification data: “1080p compatible with reduced quality.”

HD Extenders
Some call these baluns, but as to avoid arguments - as I know balun stand for “balanced/unbalanced” and digital does not conform - I will just call them extenders. HDCP and EDID are transmitted and 1080p is supported, although depending on the brand 1080p range varies from 100 to 220 feet on copper. The problem with the copper versions of these is that they are very inconsistent in our experience depending on the environment. electrical and RF interference can wreak havoc on them, even within distances specified as OK by the manufacturer.

EDID causes many problems as it seems to be the signal most difficult to handshake consistently, and if you have a power down on a unit it may not re-identify with the display, causing a reboot of the system to be necessary to get back up and running. We typically add EDID emulators into these systems to maintain the EDID connection and mitigate these restarts.

Some companies like PureLink and Intelix allow you to store EDID information in the extenders on flash memory, which also mitigates the problem. at the end of the day, if you have the budget, fiber versions are also available and not only extend range but they avoid electrical interference as well on short runs.

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About the author

Mark Coxon - Sales, Mark

Mark started his technology career at IBM in 2000 before migrating into AV integration in early 2002. He currently works at Horizon Display, an interactive multitouch hardware and software provider. Mark lives in Orange County with Lesley, his wife of 11 years and his 3 children.

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