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HDMI (High-Definition Multimedia Interface) has been a part of our entertainment systems for nearly two decades now. Though the look of the cable has remained the same over the years, the input has undergone many improvements since its release in 2002.

With each iteration of HDMI, we have been blessed with higher bandwidths, faster data rates, richer colors and better audio quality. HDMI 2.1 eARC (Enhanced Audio Return Channel) is the next evolution of the connection and has greatly improved upon its e-less predecessor. The biggest improvement over ARC is the whopping 37x boost in bandwidth and speed. With this huge jump, full resolution audio formats like Dolby TrueHD, Atmos and DTS: HD are all compatible.

eARC is designed to provide full backward-compatibility with the Audio Return Channel (ARC) so that an HDMI device with eARC can function in ARC mode if used with an ARC-only device.

eARC promises the following improvements over HDMI ARC:

• Increased Audio Payload Bandwidth to 36.8 M Mbits/second (24bits * 2(L/R) *192KHz * 4channels)
• Support for all HDMI-supported codes, sampling rates and frequencies up to 36.8 Mbits/second
• Enables additional codecs, including DTS-HD Master Audio, and Dolby TrueHD, among others (MPEG-H, AC-4, 266 DTS:X can also be supported, pending publication of the relevant standards documentation)
• Lip Sync correction protocol which ensures that picture and audio are always aligned and in sync

Technicalities of eARC

eARC does not rely on HDMI CEC (Consumer Electronics Control) protocol for connection or disconnection. eARC also has its own dedicated data channel which allows devices to exchange information about which audio formats are supported. The eARC data channel is a bi-directional, half-duplex Common Mode Data Channel. It functions as a virtual DDC channel with the eARC TX (e.g.TV) as the primary. It can be used simultaneously with the differential audio bit-stream. There is no dependency on the audio bit-stream. eARC and legacy ARC functions may co-exist in a device.

A device which supports the eARC function is required to implement both differential mode audio transport and the Common Mode Data Channel. Common mode bi-directional data transfer is supported simultaneously with the eARC differential audio bit-stream by mixing common mode for data transfers with differential mode for audio transfers.

A device that supports eARC will support the following functions over the eARC Common Mode Data Channel:

• eARC discovery
• Content protection related operations
• Heart-beat
• Status bits
• eARC capability discovery (E-EDID reading)

eARC is a new technology and takes time to become widely available in the market. So far only a few companies like Samsung and Sony have manufactured TV¡¯s with support for eARC.

Recent blogs on display technologies:

• Understanding HDMI ARC
• Connecting DisplayPort to Multiple Devices
• HDMI 2.1: Channeling the GenX Audio Video Experience
• Industry¡¯s First DisplayPort 1.4 with DSC 1.2 VIP and Test Suite

For more information on Synopsys¡¯ Display and other VIP, please visit www.synopsys.com/vip