HDMI In Consumer Electronics

By Subhabrata Chatterjee


Electrical/physical protocols

Audio and video is transmitted from the source to sink device by electrical transition minimised differential signaling mechanism. The source device must ensure electrical characteristics during transition minimised differential signaling as shown in Fig. 2.
In a typical product, the following factors may affect the electrical characteristics of HDMI transition minimised differential signaling. You must be careful about the points given below:

• Length of HDMI cable; very long cable can affect transition minimised differential signaling
• Type of cable; you should always use high-speed HDMI cable (typically 22AWG) to see jitter-free/distortion-free high-quality high-definition video
• Whether HDMI logo is present on the source device
The different kinds of issues that you may face are:
• Audio and video loss from TV
• High level of jittering in the video
• Noise in video and audio
• Audio hiss noise


CEC is a protocol whereby using only a single TV remote you can control many devices that are connected to the CEC network. A CEC network is shown in Fig. 4. All devices in the figure support CEC. This allows you to use all devices in a network with ease.

TVs and other devices talk to each other using CEC protocol, and these understand what to do and how to react and, hence, make it easy for you to control all those devices with a single remote control.

Response from each connected device also depends on CEC features that individual source devices support. For example, if a TV supports certain CEC features that the source device does not support, the source device will not react, or you may not find any affect or specific control related to that feature. So you must know which features are supported by the source device and the TV.

The latest trends show that consumers are now inclined towards higher-resolution displays (especially OLED displays) that support 4K HDMI as inputs. The next challenge for HDMI world is to enable 8K4K resolutions, so you can see more video content with super qualities in true-colour videos.

Subhabrata Chatterjee is senior technical specialist at TP Vision India Pvt Ltd



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