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ARC, eARC and getting sound out of a television

Getting sound from a television to a soundbar looks like it should be one cable and one decision. There are four routes, they carry different things, and only one of them handles modern audio formats intact.

MobilizedTV Editorial TeamPublished
Four audio routes out of a television — optical, ARC, eARC and direct source connection — compared by the audio formats each can carry.

Modern televisions have poor speakers for a good physical reason: there is no room behind the panel for anything better. So sound has to leave the set, and the route it takes decides which audio formats survive the journey.

The four routes

How audio can leave a television
RouteCarriesLimitation
Optical (S/PDIF)Stereo and compressed 5.1Fixed bandwidth; cannot carry newer formats at all
HDMI ARCStereo and compressed 5.1Enough for most broadcast and older streaming audio
HDMI eARCCompressed and uncompressed multichannel, object-based audioBoth devices must support it
Source direct to amplifierWhatever the source and amplifier shareThe television becomes a display only

What ARC was for

Audio Return Channel solved a specific problem. HDMI carries audio and video from a source to a display. But a television with its own built-in apps is a source, and its audio needs to travel back down the same cable to an amplifier.

ARC added that reverse path. Its bandwidth, however, was roughly that of the optical connection it was replacing — enough for stereo and compressed surround, and no more.

What eARC changed

Enhanced Audio Return Channel raised the available bandwidth substantially. That is the whole point of it, and it has one practical consequence: object-based and uncompressed multichannel audio can now travel from the television to the amplifier intact.

Without eARC, a television running a streaming app that offers object-based audio must either discard it or fold it down to something ARC can carry. The app may still say the format is playing. What arrives at the speakers is not it.

When routing around the television is better

If your sources are external — a streaming device, a console, a disc player — connecting them to an amplifier or soundbar first, and passing video onward to the television, avoids the return path entirely. The audio never has to survive the set's processing.

The trade is that every device in that chain must handle the video passing through it, including its resolution, frame rate, HDR format and content protection. An older receiver in the middle can become the limit on the whole system, and it is a common cause of a picture that will not reach the quality the television and source both support.

A short diagnostic

  1. No sound at all over ARC or eARC. Check that HDMI-CEC is enabled on both devices — it usually has a manufacturer-specific name — and that the cable is in the labelled ARC/eARC port at the television end.
  2. Sound works but object-based audio never appears. Either the connection is falling back to ARC, or the television's app cannot pass that format through. Check the television's audio output setting for a pass-through option rather than a re-encode.
  3. Sound drops when switching apps or inputs. Usually a CEC negotiation problem. It is often resolved by power-cycling the whole chain in order, starting with the amplifier.
  4. Sound is present but late. That is a separate problem with its own causes — see fixing audio that is out of sync.

More hardware coverage is in the Devices hub. Terms are defined in the glossary.

Sources and further reading

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MobilizedTV Editorial Team

MobilizedTV is written and edited as a single publication rather than by named individual contributors. How we research, source and correct our work is set out in the editorial policy.

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