But nowhere do you find any standards referenced to Cat 5 568A or B for HDMI. In fact, HDMI does not even have a compliance test for Cat 5 or Cat 6.
By using a 568A or B standard for HDMI, ADTs can be detrimental. These channels are balanced line, so polarity is critical. An input of a channel is typically carried right through to the opposite side with no bends or breaks.
However, when used with a 568A or 568B standard we have to consider that the two center pins 4 and 5 are wired out of phase, swapping the polarity. In addition, the pair that occupies 3 and 6 knocks the configuration out of sequential order. This little detail raises many problems with HDMI, since HDMI requires matched balance lines cabling.
So how does using 568A or B work? What happens behind the scene in the chassis can get ugly.
The only way this can be corrected is to break the sequential order from the chip set to follow pins 3 and 6 and reverse the phase on pins 3 and 4. The only way to do this is to route each of these four traces under the printed circuit board, criss-crossing them to match the pins for 568A or B wiring. At high resolutions this technique can produce over a dB of loss per channel, plus timing errors.
I imagine that because this wiring configuration has been fused in the minds of CE pros for so long, the manufacturers justify the loss in integrity for the ease of installation.
But pay particular attention to the integrity when terminating your connectors, while following whatever wire scheme a device recommends.