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USERS GUIDE
www.auroramm.com
UNDERSTANDING EDID
EDID 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.