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Avoiding HDMI Headaches

The shift from analog to digital is a hot-button issue in our industry.

The shift from analog to digital is a hot-button issue in our industry. The combination of superior quality, greater utility, and wider access to content makes HDMI connectivity the obvious choice in helping to make this transition. The compact audio/video interface for transmitting uncompressed digital data is one of two options for reading HDCP, the entertainment industry’s choice for content protection developed to protect digital video formats. With any other connection type, viewing premium content using a PC, Mac, iPad, or Blu-ray Disc player in full resolution is increasingly difficult.

Rainbow Fish Fiber Optic HDMI cable claims to support HDMI High Speed with no loss at distances up to 1,000 feet.

The HDCP Handshake. With HDMI, connected devices can read each others’ EDID data, a VESA standard data format that contains basic information about a monitor and its capabilities, and auto-configure for optimal performance, or may even control each others’ actions via the CEC channel, enabling “onetouch” command of multiple components in a system. Another important HDMI connector pin includes KSV (Keys), part of the HDCP handshake to validate that the device is authorized to receive content.

HDMI’s Limits. HDMI is a connector, so both the signals and the type of transportation used are what sets the distance limits of the technology. What signal you send also will dictate the optimal distance for a given run. For example, 640×480 resolution video may go 300 feet but on the same cable 1920×1080 will only go 50 feet. What happens when you exceed the distance? It just does not work. Unlike the old analog days when we could get some image, with digital it either works or doesn’t.

Test and Know the Specs. When working with HDMI, it’s most important to have the right tools. Test equipment will allow installers to see if the cable is pinned out correctly, and to check to see if there is too much loss on the cable. Most important is to get educated on what the new technology is and how it works. We now have to think in new ways to get the job done.

Avoiding HDMI headaches in the first place requires installers to read a product’s specs and to test products in house first, instead of on the job site. It is important to understand what the specs say. It might be an HDMI cable, but does it support 3D? What resolutions will be sent over this cable?

Extender Options. As for HDBaseT, yes it is a useful technology but if it is not installed correctly, it will fail just the same. Be aware of the manufactures that use HDBaseT and provide the tool sets, meaning ways to troubleshoot issues.

As for baluns and extenders, we recommend installers look for products that use their own power supply, instead of one that steals it from the five volts on the HDMI connector. This can, in some cases, cause issues such as a lack of picture, incomplete HDCP handshake, or system failure when higher resolutions are sent. When using extenders, installers should not add a long cable after the extender. Most extenders do not boost the signal at their output.

With manufacturers adopting for the latest HDMI formats, and residential customers wanting the latest devices to plug in, it’s often up to custom integrators to make it all work. Customers will not understand HDCP, EDID, KVS, or hot plug. They just know that if you plug in an HDMI cable, it should work. The benefit to installers is less time in the field. Happier customers equal return business. But for that to happen, installers need to get educated on the changes our industry is experiencing.

With more than 25 years in the AV industry, Kirk Holder is the senior technical curriculum developer at Crestron.