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Compatibility troubleshooting for HDMI Cables

by Stuart Berry June 10, 2020

When it comes to starting using an HDMI cable, compatibility is one of the main concerns. Nowadays, there are many types of HDMI cables on the market: Passive Copper HDMI Cable, Active Copper HDMI Cable, and Active Optical Fiber HDMI cable. Regardless of the types you choose, most of us have a hard time trying to solve the compatibility issues.

Compatibility problems originate from having two systems that are not able to properly operate together. Simply, a cable working with an HDMI device may not function with another device of the same kind.

In this article, we will give you some advice on how to solve HDMI cables compatibility issues by giving you more information about DDC, EDID and HDMI AOC cables.


About DDC

Before talking about how to solve HDMI cables compatibility issues, let’s understand the difference between DDC and EDID. In most cases, when HDMI cables have compatibility problems during data transmission, it happens because of DDC.

The Display Data Channel (DDC) is a defined standard by VESA (Video Electronics Standards Association). It describes a physical connection between a display and a video card. The DDC is a channel that sends information such as resolution, gamma values, and scanning frame to the monitor.

According to the HDMI definition, all receivers must support the enhanced DDC defined by VESA ENHANCED DISPLAY DATA CHANNEL STANDARD Version 1. This version complies with the I2C standard, which means that data must be synchronized with SCL. The HDMI source side uses the I2C interface to read and receive E-EDID.

The standard HDMI interface has hot plug detection, where the pin19 is the HPD signal. The hot plug detection allows the HDMI transmitter to judge whether the interface is connected to the HDMI display device.


HDMI devices use the signal Voltage to trigger the E-EDID reading. The signal drive low-level voltage should be of 100ms, and low-level output voltage within 0.4V.


About E-EDID

To solve HDMI cables compatibility issues, we also need to know more about E-EDID. The real data that is exchanged between the screen and the graphic adapter is called EDID. The enhanced version, the E-EDID (Enhanced Extended Display Identification Data) is a VESA standard data format.

E-EDID must follow VESA E-EDID Standard Release A, Revision 1,and supports both EDID 1.3 and EIA/CEA-861B.

The E-EDID includes basic information about a monitor and its capabilities: the display size, manufacturer, native resolution, color characteristics, frequency range limits, and more. Once this information is received, it can generate the necessary video characteristics to match the screen requirements.

E-EDID is a VESA standard data format used to communicate with the system via a DDC. Put simply, DDC is a road, while EDID is the information going through this road.

HDMI AOC Solution

one recommendation that would solve many HDMI cables compatibility issues would be using HDMI AOC. HDMI Active Optical Cable (AOC) is also a type of HDMI cable. It follows the HDMI standards and has the same requirements on the signal transmission system.

An example that has recently received high praise for its reliability is Smartavlink HDMI AOC cables. With its advanced optical engine, this new type of HDMI cables can provide full HDMI signal integrity without signal loss, delivering crystal clear digital images instantly. Extending up to 100m maximum length, this solution is already being applied in TV broadcast stations, conference room video equipment, airplane on/board video systems, security systems, and many more.



Smartavlink started with HDMI AOC development over seven years ago. They have a rich DDC/EDID/I2C application experience in designing HDMI AOC. Smartavlink HDMI AOC is among the most competitive long reach HDMI interconnection solution on the market. For more information, contact our Technical Sales Team here at ITM.

Stuart Berry
Stuart Berry


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