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User Guide
EDID Setup and its Importance
One of the most forgotten setup procedures in AV systems is the EDID. The EDID comes from the
destination (display, VTC, recorder, etc.) and must be saved into the encoder and decoder HDMI input
ports. This allows the source (Blu-ray, computers, etc.) to know the capabilities of the destination. This
includes the audio type if any, video resolution and timing, color space, color depth, and more. If no EDID
is present an HDMI device will revert to lowest resolution in DVI mode which also means no audio. If the
wrong EDID is used, the image may look pink, green, or have no image at all. To make matters more
complex, if different destinations/displays are in use in a matrix configuration, then it is important to use
an EDID with a common denominator or only one or the other destination may work. In an ideal
installation, all the destinations should have the same capabilities for optimal performance. I this is not
possible a scaler may have to be implemented to assist in the compatibility.
For example, there are 2 displays one 1080p the other 4k UHD. If the EDID of the 4K display is used, the
1080p will not see an image if the source is capable of 4K. If the 1080p EDID is used, then both will see
the image but the 4K will never benefit from 4K content. In a situation where this is unacceptable, a 4K
scaler can be used on the 1080p screen to down scale the 4K content so the 4K EDID can be used and
the better screen can have a benefit. Note scalers do add frame latency and can affect image quality
based on the quality of the scaler. This is why it is always ideal to use destinations with similar
capabilities for optimal performance.
Audio can be impacted just as easily. If a destination is 6-channel surround sound capable and the other
destination is not, then the EDID from the 5.1 destination cannot be used, or there will be no audio on the
other destination. In most commercial installations, it should not be an issue to choose the lowest
common denominator, which is 2-channel audio, but in cases where you must have surround sound then
a down-mixer for the 2-channel destination must be used.
In some cases, a custom EDID could be created, as the audio and video are mismatched between the
destinations. This can occur for example, when one destination has 4K 2-channel audio and the other
1080p with multichannel surround sound. If the EDID of the 1080p destination is used, audio will not be
present on the 4K destination. If the 4K EDID is used, there will be no video present on the 1080p
destination. The only way to solve this issue, is a new EDID combining the common features. In this case
an EDID which is set at 1080p with 2-channel audio is the solution.
