HDMI Common Issues to Avoid to Make the Installation Easier
Posted on Thursday, April 22, 2010
HDMI Extenders
When using CAT extenders keep in mind the higher the resolution the less distance you will get. 1080p will not go nearly as far as 480p so always get the distance specification for the resolution you will be using. Most extenders list their best distance at the lower resolution.
Use CAT6 unshielded solid core for new installs as it will give you the greatest distance. Only use shielded if the environment calls for it due to interference and remember to only ground one end of the shield.
Try to use dual cable CAT extenders as it can be powered from one end. It is also a much lower cost to run the extra cable verse a single cable version which usually costs 50% more.
HDMI Matrix, Switchers, Distribution Amps
If an output has a DVI destination device make certain to use an HDMI to DVI/audio converter between the HDMI output and the destination. Since the HDMI source device will output HDMI if it learns the EDID of one of the other outputs that may be HDMI, the DVI device will not get an image. If the EDID is learned from the DVI device then the HDMI outputs will not get audio although the DVI will now get video
Make certain the matrix can support HDCP on all outputs simultaneously. Some devices on the market can only support one HDCP output per input source.
If you are using a Dolby receiver on one of the outputs it may not work if the other destinations do not support surround sound. You may have to deal with the audio on a separate matrix and use the S/PDIF or optical of the source devices to get the 5.1 or better so that the HDMI output can be at 2 channel to keep compatibility with the display devices.
Always try to pick out display devices which can all handle the highest resolution and frame rate desired. Even if a display does not have a native resolution of the best display device being fed, it is important it has the ability to downscale the higher resolutions. Failure to do so will result in having to learn the EDID of a common denominator of the output devices so the 1080p 60 frame device would have to settle for 720p if this is not done. This applies to color depth as well.
Make certain the HDMI matrix, switcher, or DA can learn the EDID of any of the output devices otherwise you may be limited to the EDID built into the device.
Always read the specifications of the source and destination HDMI device for its actual capabilities. Just because it states 1.3c compliant does not require the device to support every capability of 1.3c. For example, an HDMI 1.3c DVD that can output 1080p 60 frames with 36 bit color depth, however the HDMI 1.3c LCD may only do 1080p 24 frames with 24 bit color depth. Usually the source in this case can reduce its output to the lower frame rate and color depth but you will not achieve the desired intent of the DVD capabilities due to the limitation of the LCD.