In the last 12 months, sales of HDTVs have skyrocketed. Today’s next-generation HDTVs and high-definition sources demand data transfers at a much higher data rate than previous generations of audio/video components. They place incredible bandwidth/performance demands on HDMI cables. In fact, today’s most advanced components operate very close to the limits of current HDMI technology.

Online forums have been inundated with questions about HDMI cables. As a member of the industry, I have been answering several of these questions. Here are five of the most frequently asked questions.

1. Is there really a difference between an expensive HDMI cable and a cheap cable?

There is a difference between cheap and expensive HDMI cables. It revolves around the quality of the cable’s construction and the materials used. The question is whether this will affect my setup. First you need to determine the length between your source and your screen. If this is less than 15 feet, a “standard” cable will be fine.

If it’s longer than 15 feet, it’s best to consider a “high-speed” cable. Make sure you buy from a reputable source and that the cable is marked with the HDMI logo and says it’s version 1.3 (don’t worry about a, boc, as these are just test protocols) If you live in a coastal area or high humidity, it is worth considering getting a cable with gold-plated connectors. While this won’t improve your signal, it will prevent corrosion from degrading the signal over time.

Some people assume that since the signals are digital, the cable either works or it doesn’t. Sometimes, however, the 1’s and 0’s aren’t all there due to signal degradation due to inferior cable construction. That can be especially true with audio and video sources like CDs and DVDs. The signal will gracefully degrade, up to a point, and then break. Music and video are not like data. Digital signal processors can work with a degraded signal and deliver less than perfect picture and sound.

You will never be able to improve a digital signal using expensive cable, but you can certainly degrade a signal using inferior cable.

2. Is it okay to bend HDMI cables?

It’s best to avoid bending an HDMI cable, certainly don’t bend it. What this does is change the distance between the cables, the shield and the insulation internally within the cable.

The cable manufacturing process can have a dramatic effect on how information transmitted from one side of the cable to the other looks. This means that a cable with better shielding and a more precise distance between the “intelligence” and “ground” wires will produce a better connection with less interference. Many things can affect your signal. The electrons will create a standing wave in the wire; this will create a small magnetic field around the wire. Any imperfections or splices in the cable will disrupt these waves and reflect/refract them. Magnetic information can also leak from one cable to another.

3. Should I buy HDMI 1.3a cables or HDMI 1.3b cables or what?

There is a bit of confusion in the market about all the versions. What is meant here is the specification version, not to be confused with the connector type.

As long as you choose version 1.3, you’ll be fine. The suffixes a, boc simply refer to the test protocols and do not really have an impact on the consumer, although manufacturers are using them in the market. (bigger numbers/letters are better…)

4. Will I be able to get the same video/audio quality with an HDMI to DVI-D cable?

“DVI-I” stands for “DVI-Integrated” and supports both digital and analog transfers, so it works with both digital and analog display units. “DVI-D” stands for “DVI-Digital” and only supports digital transfers. DVI also includes provision for a second data link for high resolution displays, although many devices do not implement this. On those that do, the connector is sometimes called DVI-DL (Dual Link).

When you convert HDMI to DVI, you lose the audio as DVI doesn’t support any audio signal. You will need to take a separate cable link between your source and the sound system for this to work.

You’ll also need to check the software settings on your source so they know you’re not outputting audio from the HDMI but from a separate output.

Some newer DVD players, televisions (including HDTVs), and video projectors have DVI/HDCP connectors; these are physically the same as DVI connectors but transmit an encrypted signal using the HDCP protocol for copy protection. Computers with DVI video connectors can use many DVI-equipped HDTVs as their display; however, due to digital rights management, it is unclear whether such systems will be able to play protected content, as the link is not encrypted.

5. When I connect the Blu-ray from my laptop to my HDTV, I get an error about copyright infringement. What I can do?

You are facing HDCP (high definition copy protection) issue here.

HDCP is a form of digital copy protection developed by Intel Corporation to prevent copying of digital video and audio content as it travels through various cables and connections, even if such copying is permitted under fair use laws. Each device communicates with the other and then passes an encryption key to say it’s okay to display or play the signal. It does this for every frame, typically 30 times per second. If you are having issues with blank audio or video, it is very likely that one of your devices does not support HDCP.

Generally, if you connect with HDMI throughout the connection chain, you shouldn’t have this problem.