One approach to distributing AV around the house is to use HDMI.  HDMI cables however have a length limit.  15m for the higher quality cables (according to Wikipedia), but I have heard others saying more like 5m.  There are different HDMI distribution technologies like splitters and matrixes that I might write up separately, but my first goal was just to try and get the Foxtel pay TV HDMI output sent off to the bedroom.

I had heard about HDMI extenders which convert HDMI signals to something that is sent over Cat-5, Cat-5e, or Cat-6 network cables (these are different cable qualities, where I believe Cat-6 has less signal loss so can go farther and at higher speeds).  So I went to my local Jaycar electronics store and got a unit (with a 7 day return policy) for $169 (catalog item AC1698).

The unit I got has an IR return (necessary to control the Foxtel pay TV to change channels etc) and so needed two cable runs.  The labels on the box indicated one was for the AV signals, the other was for controls.  I already have cables in the walls when the house was built running back to a patch panel.  So I wanted to run it through the existing cables to keep things neat and tidy.

Unfortunately I will be using the return policy.  After trying many combinations of cables etc, the best I can get is pretty good (can control the Foxtel, can view its HDMI output), but the picture goes black once every minute or two.  Just drops out completely.  Its only for half a second or so, but not acceptable.

I suspect its not the extender at fault, but my wiring set up.  Changing cables etc did make a significant improvement.  I have Cat-6 cables in the walls, but there are lots of connectors in the cable: short cable from back of extender to plate on wall, cable in wall off to patch panel, jumper cable between two patch panel ports, cable in wall off to bedroom, jumper cable from plate on wall to HDMI extender receiver box.

I have not tried to wire the device up with a direct cable.  I don’t have the cable (or the time and inclination) to mess around with it much further.  After changing cables etc and noticing a real difference, I truly believe the concept is sound, but you really want a direct cable without too many connectors.  I believe each connector degrades the signal quality.

If I am correct, then HDMI extenders are best suited for direct runs from the source to the destination.  This is not ideal for me.  It means I need to know where all the equipment is going to reside and be viewed from up front, and put enough cables in place.  So I am off to look a bit closer at DLNA to see if it offers an alternative solution.

UPDATE 8 Nov 2010: HDCP and the Foxtel HDMI port

Just learnt some more today.  First, my brother suggested that part of my trouble might be because the cable runs I am using are not the same length.  I just used whatever cables I had around for jumper leads.  The signal on the two cables could become out of sync due to the length distances.  (He actually went into a whole lot of stuff about impedance levels, reflections introduced by lower quality connectors, and so on – but I cannot say it all sunk in!)

However I also discovered the Foxtel HDMI port uses HDCP (High-bandwidth Digital Content Protection) to protect the digital content from being copied (pirated).  When the HDMI extender is plugged into the HDMI port but the TV in the master bedroom is not viewing the HDMI port, the Foxtel puts up banners about HDCP errors.  My plasma is a bit old and does not have a HDMI input port, so I use the component output ports of the Foxtel to connect up to the plasma in the living room.

There are HDMI matrixes that claim to be HDCP compliant (such as this one), so a combination of a HDMI matrix or splitter, a HDMI extender for the bedroom run, and both TVs supporting HDMI might all work together.  Using a mix of HDMI and non-HDMI video ports on the Foxtel IQ box however seems doomed to failure (having to turn the bedroom TV on to watch in living area is not a serious option).