Understanding EDID Management in Distributed Video Systems

For years AV Technology has been plug and play, things just worked....

In today's world of HDMI distribution, things are different. Variables between displays and sources have continued to increase in complexity. Each product has their own detailed specifications that are slightly different than other, similar products. These specifications rely on something called EDID (Extended Display Identification Data). Contained within the EDID information is metadata sending preferred resolution, audio, timing, and a host of other information pertaining to the capabilities of the display.

When a source is connected to the display the EDID information is sent back to the source, which will then generate the correct signal. Most displays have a setting that must be enabled to do HDR formats, these settings can change the EDID information.

EDID Flow

The largest problem in distributed systems is the mismatch of EDIDs from different models and manufacturers. AV manufacturers handle these issues in two different ways, unmanaged and managed. In the example below we compare two matrix switchers, a 4x2 with unmanaged EDIDs and a 4x2 with managed EDIDs. 

Unmanaged EDID

• Unmanaged switches present no EDID configuration options. It is picked by the switch and presented to sources via the HDMI Input.
• An unmanaged switch may only take the lowest common denominator between the two displays (1080p60Hz on both).
• Another possibility is that the EDID is read from one output causing an older, legacy display to not display the image.
• Sure everything may work, but are you providing the picture the customer pays for?

Managed EDID

• Managed switches present EDID configuration options. Most commonly these EDIDs can be configured on each individual input.
• Managed switches can contain default EDIDs and may have the capability to copy from the display.
• Each source reads an EDID on each input (for this example four individual EDIDs are used). As long as the EDIDs used are not greater than the capabilities of your highest quality display, the image will be shown on the display.

• Some displays are picky with their EDIDs and require a signal that meets their specific request for EDID information. This is when an EDID may be required to copy to an input.
• While this may mean legacy displays do not provide an image, a scaler can be used to generate the correct image. A good 4K60 4:4:4 matrix switch should include at least one scalable port, like the AC-MX42-AUHD from AVPro Edge.
• This provides the quality your customers pay for, and with a scalable port, an all-in-one solution.

​Once you have an understanding of managing EDID, that knowledge can be used to tackle all kinds of problems both in the field and in design. From shortening sync times, fixing color space, or just getting the best quality audio and video, EDID management can change the whole system.
 
AVPro Edge has made a huge leap forward in EDID Management. Using the AC-DA12-AUHD-GEN2, AVPro has created an EDID Compiler mode which uses the video capabilities of a display or projector and combines it with the audio capabilities of an AVR or soundbar. The DA12 also includes a 1080p downscale port allowing support for a legacy AVR. This can bring Dolby Atmos to your home theater while avoiding AVR limitations and shortening sync times. AVPro Edge continues to push the edge of innovation.

This tech tip is written by Sam Metivier (AVPro & Murideo's Tech Team)