Technology

More and more manufacturers unlock HDMI audio return channel

More and more manufacturers unlock HDMI audio return channel

Thanks to TV apps, you can use video streaming services on today’s smart TVs without an external player and additional remote control. But there is currently one drawback: If the service streams 3D sound, you usually do not get it from the TV app to the AV receiver. An enhanced audio return channel (eARC) in the HDMI cable will help in the future.

Although many older TVs do not support HDMI eARC (a positive exception are Sony’s current models of the A9F and Z9F series), at least with modern AV receivers, however, a firmware update is often enough: the chip manufacturer Lattice Semiconductor (took over HDMI co-developer Silicon in 2015) Image) has delivered suitable HDMI chips since last year, which are already being used by Denon, Marantz, Pioneer and Yamaha.

Owners of an Onkyo TX-RZ830 can look forward to a free eARC update in mid-October. Also Sony is currently upgrading its AV receivers and soundbars with the necessary firmware. According to US reports, eARC updates for Denon and Marantz devices from 2017 and 2018 will follow on October 31. And also Yamaha wants to retrofit its AV receivers and preamplifiers with eARC for free via firmware update – until the end of the year.

eARC is part of the HDMI 2.1 specification released late last year. The associated eARC test specification followed in August 2018. For other parts of HDMI 2.1, including those around 8K, the release of test specifications is not expected until spring 2019.

Where is the problem?
The HDMI 1.4 specified audio return channel is one of the truly practical features of the digital interface. Thanks to ARC, a TV can not only receive audio and video data on at least one of its HDMI inputs, but can also return digital audio to an AV receiver or soundbar – for example, from its built-in TV receiver, TV app or player connected to one of its other HDMI inputs. This saves separate connections and stripping for the transmission of digital audio.

But the technical development has now overtaken ARC: Video streaming services are increasingly offering films and series with 3D sound including height channels in Dolby Atmos format, the codec “Dolby Digital Plus” forms the basis. From a technical point of view, however, ARC only complies with a digital audio output integrated in HDMI, as found on many devices under the name SPDIF. And this interface was developed only for the transmission of PCM sound with two channels and Dolby Digital and DTS, each with up to 5.1 channels. The transfer of additional height information is not specified at ARC.

The range is sufficient for the use of Dolby Digital Plus in itself – as LG for years and Samsung since this year prove by the companies off the specification of their 4K TVs successfully send Atmos information via ARC to AV receivers , Most built-in TV HDMI transmitter chips dominate this trick but not today.

What does eARC bring?
eARC transmits up to eight-channel uncompressed PCM sound with 24-bit resolution and a sampling frequency of 192 kHz. As compressed codecs, it supports the Lossy variants Dolby Digital Pl…

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