HDMI and its cables have been around for years now. Initially released in 2002, HDMI became the gold standard for audio-video connections over the years.
One of the reasons HDMI has had so much longevity or continues to be relevant are the periodic updates HDMI releases or its keeping up with the times.
As the industry’s AV requirements and setups change, HDMI upgrades its offerings to accommodate those new developments, such as ARC and eARC.
ARC (audio return channel) is one of the functionalities HDMI introduced in 2009, rendering the optical audio cable used in previous HDMI setups irrelevant.
So, what is HDMI ARC? How is it different from traditional HDMI? How does it cut out a cable from a multi-device HDMI setup?
Read on for the answers to the questions and more.
What is HDMI?
HDMI (High-Definition Multimedia Interface) is an audio-video standard for transmitting uncompressed video information and uncompressed/compressed digital audio data between HDMI-compatible devices.
The HDMI Forum governs the standard. It is a group comprising more than 80 entities that collectively determine how HDMI must function and how the standard’s new extensions shall work going forward.
Due to how convenient HDMI makes sending high-quality sound information and digital images to TVs, amplifiers, soundbars, etc., from a source device using a single cable, it is currently the de facto audio-video connection.
The first HDMI standard (HDMI 1.0) came out in December 2002. The original version had uncompressed digital audio provision for a maximum of eight channels and supported up to 4.95 Gbps of data transfer.
HDMI 1.4 was released in May 2009 and was a significant update from a usability standpoint. One new and helpful feature it introduced was ARC. The latest widely available HDMI is v2.1, which ushered in eARC.
One big plus of HDMI is that it uses the 19-pin connector across all its backward-compatible versions. To learn more about HDMI, read our article HDMI vs. MHL: Understanding the Difference Between Them.
What is HDMI ARC/eARC?
ARC (Audio Return Channel) is a feature added to the HDMI standard with v1.4 or above. An HDMI ARC port is labeled “ARC” for easy identification.
An HDMI ARC port or cable appears and functions the same as a regular HDMI cable but has a “return channel,” which allows audio information to travel both ways and eliminates the requirement for a discrete audio connection.
Note that traditional HDMI supports only one-lane transmission of audio-video signals between a source and a display device.
HDMI ARC can transmit different audio formats, such as uncompressed stereo, DTS, Dolby Digital.
Note that ARC works if all connected devices (audio, TV, etc.) support the feature. The same is the case with eARC.
HDMI eARC is “enhanced” HDMI ARC. It supports advanced audio formats and higher bandwidth. ARC doesn’t support Dolby Atmos natively, but eARC does.
Besides, there are many other ways HDMI eARC improves upon ARC. More on that later.
HDMI vs. HDMI ARC: Breaking Them Down
HDMI ARC’s foundation is in HDMI. But ARC is so extremely handy; anything before it is now obsolete. From simplified audio setups to HD video transmission, the following are ways in which HDMI ARC betters HDMI.
Less Number of Cables in AV Setup
HDMI ARC uses fewer cables in an AV setup than traditional HDMI since ARC doesn’t require an extra audio cable.
AV setup before and after the advent of HDMI ARC:
(a) before the introduction of HDMI ARC; (b) after the introduction of HDMI ARC
|Before the introduction of HDMI ARC (HDMI 1.3 or below)||After the introduction of HDMI ARC (HDMI 1.4 or above)|
|AV source connection: Hook the first HDMI cord to the soundbar and gaming console. It will transmit audio-video signals.||AV source connection: Use an HDMI cable to connect the soundbar and gaming console to transmit audio and video signals.|
|Video connection: Incorporate another HDMI cord, connecting the TV and soundbar. As non-ARC HDMI cannot demarcate audio-video signals and sends them together, you’ll need an audio return cord to transmit audio signals to the soundbar.||Audio return connection: Use another HDMI cord to the TV and soundbar. The cable shall send AV information to the TV from the gaming console and transmit back audio signals to the soundbar.
|Audio return connection: Connect a 3.5mm or optical audio cable to the soundbar and TV to transmit only audio signals from the TV back to the soundbar.|
Although HDMI cables, ports, and connectors haven’t changed much externally, their specifications differ. The HDMI 1.4 or above version that ARC requires to work is not the same as the immediately preceding and now obsolete HDMI 1.3 or below version.
Here is a table listing all HDMI versions and their key specifications:
|HDMI Versions||Maximum Resolution at Refresh Rate||Bandwidth (Gbit/s)||HDR|
|HDMI 1.0||1080p @ 60 Hz||4.95||No|
|HDMI 1.1||1080p @ 60 Hz||4.95||No|
|HDMI 1.2||1440p @ 30 Hz||4.95||No|
|HDMI 1.2a||1440p @ 30 Hz||4.95||No|
|HDMI 1.3||5K @ 30 Hz (1)||10.2||No|
|HDMI 1.4 (ARC starts to be included)||5K @ 30 Hz (1)||10.2||No|
|HDMI 1.4a||5K @ 30 Hz (1)||10.2||No|
|HDMI 1.4b||5K @ 30 Hz (1)||10.2||No|
|HDMI 2.0||8K @ 30 Hz (1)||18.0||No|
|HDMI 2.0a||8K @ 30 Hz (1)||18.0||Yes|
|HDMI 2.0b||8K @ 30 Hz (1)||18.0||Yes|
|HDMI 2.1 (eARC starts to be included)||10K @ 120 Hz (2)||48.0||Yes|
|HDMI 2.1a||10K @ 120 Hz (2)||48.0||Yes|
(1): Possible by using Y′CBCR with 4:2:0 subsampling; (2): Possible by using Display Stream Compression (DSC)
Are There HDMI ARC Cables?
Yes, there are HDMI ARC cables. Technically speaking, all cables supporting HDMI 1.4 standards or greater are HDMI ARC cords.
Cables that support up to HDMI 1.3 are not HDMI ARC cables since the ARC feature is only added to HDMI cables v1.4 or higher.
And HDMI 1.3 is now obsolete, so all HDMI cables available on the market belong to v1.4 and subsequent standards.
That means even if you’re shopping for an HDMI ARC cable unaware of the minimum HDMI 1.4 base standard requirement, you’d still buy the suitable HDMI cable.
HDMI ARC vs. HDMI eARC: How is HDMI eARC More Enhanced Than HDMI ARC?
HDMI ARC was undoubtedly a significant improvement over non-ARC HDMI or optical audio connections. But it wasn’t perfect.
For instance, it needed more resources to handle lossy Dolby Atmos. ARC instead supports Dolby Digital Plus, Atmos’ lossy version.
The table below showcases other aspects in which eARC is better than ARC.
|HDMI ARC||HDMI eARC|
|HDMI Standard||HDMI 1.4 (or higher)||HDMI 2.1 (or later)|
|Cable||High-Speed HDMI||High-Speed HDMI with Ethernet|
|Maximum Audio Bandwidth||1 Mbps||37 Mbps|
|Maximum Audio Channels||8||32|
- High-Speed HDMI and High-Speed HDMI with Ethernet are actual HDMI cable certifications. To learn more about the different HDMI cable classes, click here.
- eARC’s 37 Mbps bandwidth capability enables it to pass various high-resolution audio formats, such as Dolby True HD, DTS:X, Dolby Atmos (uncompressed), or DTS-HD Master Audio.
- The High-Speed HDMI with Ethernet cable will enable the eARC feature. However, to benefit from all HDMI 2.1 features, such as 48 Gbps bandwidth support and support for video resolutions of more than 4K and up to 10K at 120 Hz, an Ultra High-Speed HDMI cord will be needed.
- eARC offers the automatic lip-sync correction feature, ensuring that audio always aligns with the video. The feature can be found in ARC but is mandatory with eARC.
- Both HDMI ARC and eARC support stereo and compressed 5.1 audio, but the experience is the best with eARC. eARC supports uncompressed 5.1 and 7.1 audio formats.
ARC and eARC are not essential features. However, with TV manufacturers equipping their devices with serious features such as variable refresh rate, quick frame transport, 4K at 120 Hz, etc., it’s hard to use the TV without ARC/eARC.
HDMI ARC becomes superfluous if you only use your TV for video and audio and don’t use a soundbar or AV receiver.
But because most TVs don’t sound as good as dedicated external speakers, especially when watching movies, ARC and eARC that seamlessly connect TVs to soundbars and AV receivers become almost mandatory.
HDMI ARC added increased convenience and capabilities to audio transmission. eARC took that further with more bandwidth, higher-quality audio format support, broadened audio channel capacities, etc., catering to home theater enthusiasts and audiophiles seeking immersive audio experiences and lossless audio formats.
Long story short, ARC is a feature of HDMI. It is among the best features to come up in the home theater space in recent years, with the eARC raising the bar.
Catherine Tramell has been covering technology as a freelance writer for over a decade. She has been writing for Pointer Clicker for over a year, further expanding her expertise as a tech columnist. Catherine likes spending time with her family and friends and her pastimes are reading books and news articles.