Audio Return Channel (ARC vs eARC)
 

Good info to have when shopping for a new TV set. Most TV sets will have the ARC but not all have the EARC right now. If that is important of course, for implementation of Dolby Atmos content as it becomes more widely available.

https://youtu.be/tgxwDSbixYs

HDMI® Enhanced Audio Return Channel (eARC)
HDMI 2.1 features Enhanced Audio Return Channel (eARC) which is an advancement over the previous Audio Return Channel (ARC).

eARC simplifies connectivity and provides greater ease of use for multiple components discovery and audio optimization. It supports the latest high-bitrate audio formats up to192kHz, 24-bit, and uncompressed 5.1 and 7.1, and 32-channel uncompressed audio. It also supports DTS-HD Master Audio™, DTS:X®, Dolby® TrueHD, Dolby Atmos®.

Now it’s easier than ever to experience movie theater quality sound in a living room for an immersive multi-dimensional experience and enhanced audio detail and depth.

eARC enables the audio to a TV that originates from cable, satellite, streaming or source devices to be sent to an AVR or sound bar through a single HDMI cable. This ensures the simplicity of connectivity and that the original audio can be experienced.


Further reading. https://hdmi.org/spec21sub/enhanceda...20HDMI%20cable.

HDMI ARC does not have enough data capacity to support the transmission of Dolby Atmos content that is encoded using Dolby TrueHD, which is the format used on Blu-ray Disc and UHD Blu-ray Disc. ... Today, this feature is only supported in televisions that have native Dolby Atmos decoding