Crestron HD-DA-2-QUAD Specifications download pdf (Page 6)

Crestron DigitialMedia

™

Design Guide

Quality: Because HDMI is a digital interface, it has lossless transmission and provides the best video quality, unlike analog

video. The difference is especially noticeable in low brightness scenes and at higher resolutions, such as 1080p. Digital video

is sharper than component, and eliminates the softness and ghosting found with component. Small high contrast details, such

as text, especially bring out this difference.

Ease of use: HDMI combines video and multi-channel audio in a single cable, eliminating the cost, complexity, and confusion

of multiple cables currently used in AV systems. This is particularly beneficial when equipment is upgraded or added.

Intelligence: HDMI supports two-way communication between the video source (such as a DVD player) and the DTV, enabling

new functionality such as automatic configuration. By using HDMI, devices automatically deliver the most effective formats

(e.g., 480p vs. 720p, 16:9 vs. 4:3) for the displays to which it is connected, eliminating the need for external intervention

to identify the best resolutions and audio formats.

It’s Not Just Cable Length

The promise of HDMI is great. One cable carrying uncompressed digital HD video and audio; what’s not to like? But mention

HDMI to an AV integrator and you’re likely to get an expletive in response. A quick search of online forums and industry trade

publications uncovers a slew of HDMI related complaints, ranging from annoying switching delays and screen flashing to

complete audio and video failure.

There are two primary reasons for HDMI problems: bandwidth and complexity. Uncompressed HD video requires enormous

digital bandwidth, which is notoriously difficult to push through copper wire. Add popular features such as 1080p resolution

and the potential offered by Deep Color, and the problem worsens.

There are a number of products appearing on the market that attempt to address this issue, some of which actually work

quite well. But the under-discussed issue is the sheer complexity of HDMI.

HDMI is a full-duplex digital communications interface. The creators of HDMI took advantage of its digital nature, and added

several communications mechanisms to automatically control and encrypt content. Unfortunately, the custom installation

industry wasn’t considered in the design process, and HDMI doesn’t scale well. Compounding the problem is the fact that

digital control is relatively new to most of the major AV distribution players, so the learning curve has been very steep.

Though much more complex than analog, HDMI isn’t nearly as complicated as home automation, Ethernet, or any of the

myriad wireless protocols. Companies with experience in these fields are in a position to implement HDMI in environments

that the designers hadn’t anticipated.

This portion of the guide addresses the need for the move to HDMI and explains the new features that HDMI supports. We’ll

demystify the “handshaking” that occurs between HDMI sources, repeaters, and displays, and explore the cause of some

common problems experienced in the field.

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Crestron HD-DA-2-QUAD Specifications Page 6