Making the HDMI Connection: All Versions of HDMI Explained

HDMI is a consumer friendly connection that simplifies and improves the home theatre. One cable, that carries both audio and video signals, can do the job that previously required up to eleven separate cables. The high bandwidth of HDMI allows for transmission of up to 1080p content (component cables top out at 1080i). Since the HDMI signal is purely digital, it eliminates the quality degradation in the digital to analogue (and back again) conversion process. There is also no interference within the cable itself. Two-way communication (of device command controls) is supported, which can greatly ease the configuration and operation of multiple HDMI devices.

Although component cables do have the bandwidth to carry high definition video (up to 1080i), content providers like movie studios, didn't want to give consumers (or pirates) an easy route for copying high definition movies. With High-bandwidth Digital Content Protection (HDCP) as part of the HDMI specification, consumers could now enjoy up-conversion of standard DVDs and the high-def content of HD DVD and Blu-ray without easily being able to duplicate high definition copyrighted material, and thus keeping the movie studios happy.

Another benefit is that HDMI has been accepted as a worldwide standard. This means that new consumer electronics will all have the same connector regardless of what country or region they are manufactured for.

The HDMI format is a great advancement for the home theatre, however its implementation has been somewhat messy. Currently, four different versions of HDMI can be found in various audio and video components.

There have been incremental improvements to the initial release of HDMI 1.0. DVD-Audio support was a major feature added to version 1.1. But it wasn't until HDMI 1.2 that SACD support was introduced. Hence, high resolution multi-channel music lovers had to wait until the release of HDMI 1.2 to fully enjoy their music collections via a single cable. It also became abundantly clear that PCs were becoming more integrated into the home theatre and so HDMI included better support for PC connectivity.

Finally, there is HDMI 1.3. Released in June of 2006, this is currently the latest version. Push for the upgrade from version 1.2 came from the imminent arrival of HD DVD and Blu-ray. One of the first products to support HDMI 1.3 was Sony's PS3. Expect an abundance of consumer electronics to be released this year with support for HDMI 1.3.

This new version doubles the bandwidth from 165 MHz to 340 MHz. This translates into an increase in bitrate from 4.9 Gbps to 10.2 Gbps, allowing the maximum bit depth of colour to go from 8 bits per channel to 16 bits per channel. While previous versions of HDMI allowed for a maximum of 17 million colours, HDMI 1.3 allows for 2800 Trillion colours, or Deep Color as the marketing gurus have dubbed it.

Video refresh rate capability of up to 120 Hz is also an upgrade over the 60 Hz of previous HDMI versions. And even though it's way in the distance, HDMI 1.3 also supports the 1440p resolution.

Finally, there's also support for the much anticipated lossless audio formats Dolby True HD and DTS HD Master Audio.

There are no current plans for any newer versions of HDMI. Hopefully version 1.3 will be the standard for at least the new several years. Otherwise, no one will be able to keep up.

Do you need HDMI 1.3 to enjoy high definition video and audio? No.

Even though Deep Color capable displays are starting to trickle out, high-def movies encoded with Deep Color aren't on the market. And even if they were, you'd still be able to enjoy HD DVD and Blu-ray movies in their current high definition glory through any version of HDMI.

What about lossless audio? You also don't need HDMI 1.3 for high resolution sound. If your HD DVD or Blu-ray player (eventually) decodes the lossless formats internally, then the uncompressed sound can be sent from any player equipped with any version of HDMI to any receiver equipped with any version of HDMI. The only circumstance where HDMI 1.3 is necessary for sound is if you want your receiver to do the decoding of the lossless audio. Sure, many of us prefer to use the (generally) better decoders built into receivers rather than use the DVD player's decoder and Digital to Analogue Converters, but it's not necessary.

But, there have been problems. The first problem with HDMI was the connector itself. You would think that any HDMI plug would fit into any HDMI input. Alas, this is not the case. Sometimes the plastic surrounding the plug is too big to properly insert it into the input jack. And when it does fit, it sometimes falls out. Although to be fair, this is more of an issue for reviewers who need to constantly swap devices in and out of their equipment racks.

The second problem is HDCP. No, we're not going to get into the consumer rights debate. We're talking about compatibility issues. We alluded to DVI incompatibility earlier. The problem is not all DVI equipped displays had HDCP compliance. If this is the case with your display, you will not be able to connect, a DVD player say, using the HDMI output with an HDMI to DVI cable.

The biggest headache with HDCP is the "handshake." Sounds friendly enough, doesn't it? Unfortunately the "hand shake" hasn't always worked properly and it has lead to interoperability problems between HDMI devices.

Some components will work fine with each other, but some won't. The most maddening situation is when you're watching a movie and at some point he DVD player and TV need to shake again but this time they get it wrong and you lose the picture.

The HDCP "handshake" has become enough of an issue that the creators of HDMI, Silicon Image, have recently established Simplay Labs. Their aim is to test and certify HDMI products so that compatibility is ensured. Certified products (including cables) carry the SimplayHD logo.

Shopping for HDMI cables

Buying HDMI cables should be much simpler than analogue cables. Any HDMI cable will work with every audio video component, regardless of what version of HDMI the component offers.

With HDMI cables, there is no need for shielding since there is no interference within the cable. A thicker copper core will however allow a longer cable run. For runs longer than 5 meters, a thicker cable is recommended because of inevitable signal attenuation. Signal boosters are available for transmitting a signal over longer distances.

Pay attention to the build quality of HDMI cables. Look for cables that have the HDMI logo on them. This means that the product has been tested at one of the HDMI authorized testing centres and meets the HDMI specification.

One other aspect to consider is the plug itself. While gold plated plugs are generally believed to be better, you should be careful. Although silver is a better conductor, gold platting reduces the likelihood of corrosion. The problem is that poorly made, inexpensive cables use poorly applied, thin coats of gold platting. The platting is susceptible to flaking or scratching off and in the end may provide a poor conduit for the signal.

HDMI is a really great format that offers many benefits over analogue cables. Hopefully 2007 will be the year that HD home theatre truly breaks out.

To learn how to properly connect your home theatre, please read our Connecting your Home Theatre with the proper cables article.

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