HDMI 101

How important is HDMI 1.3 anyway?

The HDMI standard was developed with noble intentions. Most people in the home theater hobby know the hazards of cable clutter. When you have a lot of equipment connected this way and that by separate audio and video cables, you wind up with a tangled mess of wires behind your equipment rack or entertainment center. The problem is compounded by component video (three cables just for picture) and multichannel analog audio (six to eight more cables!). Now factor in a DVR, a couple of DVD players, a Blu-ray player, a video processor, and an A/V receiver all interconnected in one theater room. If you want to add or remove any piece of equipment, you’ll have to squat behind the rack with a flashlight and trying to trace each cable from end to end. Which unit did this blue one come from? If I plug that red cable into here, will I get my picture back, or will my speakers start blaring obnoxious noises?

HDMI was supposed to help with all that. One cable carries both video and audio. Better yet, it carries high-definition video and high- resolution multichannel audio, plus it has all the latest copy-protection protocols that the Hollywood studios demand. In theory, it’s the perfect connection standard for Blu-ray. One HDMI cable out from the Blu-ray player to an A/V receiver, and another HDMI cable out from the receiver to an HDTV should be all it takes to get stunning 1080p picture and lossless audio, all fully encrypted with a minimum of cable clutter. So why are there so many different versions of HDMI? And which ones do you need to be concerned with?

HDMI is an evolving standard that first came to market before all of its features were finalized. The original HDMI version 1.0 established the basic parameters for transmitting high- definition video and uncompressed audio. This was followed by several revisions that added, among other features, support for the DVD-Audio format and some PC applications. For home theater purposes, any HDMI connection type from 1.0 to 1.2a will transmit 1080p picture and multichannel PCM sound equally well. However, at the very least, they will not carry the native digital bitstreams for the advanced Dolby TrueHD or DTS-HD Master Audio lossless audio formats.

The most significant revision to the HDMI spec came with version 1.3, which added support for a few new features that are useful for home theater applications. (Later versions such as 1.3a, 1.3b, and 1.3c add more remote control options and other improvements to their functionality, but they add nothing directly related to additional core audio or video.) In order to benefit from these new features, both ends of the signal chain—as well as any switches, splitters, or other intermediary devices—must be compliant with HDMI 1.3. As a result, HDMI 1.3 has become a marketing tool for many manufacturers to encourage consumers to upgrade their Blu-ray players, A/V receivers, and even all of their cables. You wouldn’t want to be noncompliant with all of the latest features, would you? Of course, this begs the question: Does a Blu-ray viewer really need HDMI 1.3 to get the most out of the format? The answer is a resounding maybe. To delve a little deeper, let’s take a look at what HDMI 1.3 offers that you can’t get in previous versions.

On the video side of things, HDMI 1.3 increases signal bandwidth and allows for the transmission of more color detail. Only HDMI 1.3+ can carry the Deep Color or x.v.YCC formats that promise billions of possible colors, smoother color gradients, and the elimination of banding artifacts. (Naturally, these will only work if both the source and the display are compatible.) That certainly sounds great, but there’s just one problem. The Blu-ray spec doesn’t support either Deep Color or x.v.YCC. Even if a Blu-ray player claims compatibility with these formats (and several do), no Blu-ray Discs are actually encoded with an extended color gamut. Those billions of new colors don’t exist in the Blu-ray source. Any standard HDMI connection can transmit the full video quality that’s available on a Blu-ray Disc.


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