Tuesday, August 22, 2006

How do the audio/Video over CAT5 Baluns work?

Q) How do the audio/Video over CAT5 Baluns work? Do these allow me to run audio/video over an Ethernet Network? Does the Audio/Video pass through network Hubs, Routers, Switches etc?

A) The A/V signals are not converted to Ethernet, they are converted to "balanced" audio or video signals
for transmission over twisted pair wiring. The cables should be dedicated to A/V signals, and should NOT be connected to your Ethernet network, Ethernet hubs, routers, etc. Here are the basics:
The Balun converts the audio or video signal into a "balanced" audio or video signal which will allow any picked up noise to be canceled out at the receiving balun. It is very important that the "halves" of a balanced run be as similar as possible in length and other attributes. Otherwise the ability to cancel out noise is effected. Using CAT6 or high quality CAT5e cable with tight tolerances will give the best possible results.
Each CAT5 balanced signal run has to be separate - you can't do splices or "Y" cables with balanced signals.You have to split the signals with distribution amplifiers before the baluns, which means you would need a separate balun for each and every sent and received audio/video signal. There are some baluns that combine audio and video or multiple separate video components (like separate RGB signals or Y-Pr-Pb) into one box, but these boxes actually contain multiple baluns in one box and will require more and more twisted pairs to be used within the CAT5 cable. If more signals are needed than there are twisted pairs in a CAT5 cable, then multiple CAT5 cables would be necessary.

Thursday, August 03, 2006

How to connect HDMI to VGA/Component Video?

(Q) I have a HDMI male cable but my projector has only a VGA female input.
So, what i need is an adapter for the HDMI male with a HDMI female which can then connect to a 15 point VGA female. The problem is that it is all wired and the basement is finished.

(A) The first question that needs answering in these scenarios is what will be connected at the other end? Is it a DVD player with HDMI, a set top box with HDMI or DVI, or is it a computer with DVI?
Virtually all components with HDMI output, and most devices (other than computers) with DVI output have copy protection scheme built-in called "HDCP". When connecting video source devices like DVD players or Cable/Satellite Set Top Boxes that have HDCP, you must use a display with a digital input (DVI or HDMI) that supports HDCP as well. If the source has HDCP and the display does not - you will not get a picture.
All right, but you don't want to connect a digital device, you just want to connect your analog display with Component Video or VGA. Why can't you do this? Well, first you would need to convert the Digital video to analog video, and this is possible, although these converters do cost several hundred dollars. If there was no HDCP involved this would do it. It is not legal to make devices that will take an HDCP encrypted digital signal in and output that signal as analog video. The "rules" are actually a good deal more complicated than this, and there have been devices made that broke the rules, but they are very hard to find and not cheap in any case.
So what are your options?
1) Use a Source device (DVD player/Computer) that does not have HDCP and then use a Digital video to analog video converter to convert the digital video to the VGA signal you need. Be careful when selecting a DVD player, since most with digital outputs have HDCP. A DVI/HDMI adapter is generally not going to cause any problems.

Some Digital to analog video converter examples:
Gefen converters
Calrad converter

2) Replace the Projector with one that has a HDMI or DVI input with HDCP.

3) Run a "temporary" cable until you can do #1 or #2.