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The Power Of HDMI ARC

HDMI ARC, What is it and Why You Should Care?

HDMI has been introduced during 2002 for delivering high quality digital video and audio to and from consumer electronic devices. HDMI 2.0 supports only 4K video but with the arrival of HDMI 2.1, CEA introduced many remarkable features including the support of up to 8k resolutions at 60fps.

HDMI ARC (Audio Return Channel) is a protocol which sits within HDMI standard and it was introduced to simplify and reduce the number of cables required for a set up. HDMI ARC is based on IEC 60958-1 Specification. The Audio Return Channel is controlled using CEC messages. CEC channel is optionally used for functions such as automatic set up tasks or tasks related to remote control usage.

What Is ARC?

If user wants to use set top box/Blu-ray player/gaming console plugged into TV via HDMI, user would not intend to use TV’s speakers for audio but would rather want to enjoy the sound system played through an amplifier. For this setup, user would connect an optical cable (SPDIF-Sony/Philips Digital interface to transmit digital audio) from TV to audio device. However, this set up seems to be complicated and chaotic. To overcome this problem, ARC was introduced.

HDMI ARC removes the need of an optical cable and allows to send audio via HDMI as explained diagrammatically below. ARC sends audio signals in and out of a device over a single HDMI port.

Due to the flexibility that HDMI standard offers, various audio formats (such as Dolby Digital, DTS and PCM audio) can be transmitted via HDMI ARC when compared to optical cable.

HDMI ARC was introduced to replace SPDIF as shown in the above diagram, but it has limitations too. The bandwidth is limited to only 1 Mbps and one may end up with lower sound quality. Many audio formats such as Dolby Atmos and DTS are not supported.

To overcome above limitations, HDMI 2.1 introduced much improved audio technology called Enhanced Audio Return Channel (eARC).

Let’s understand in next blog what is eARC and its advantages over HDMI ARC.

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