Enhanced Audio Return Channel (also known as eARC) is the next generation of ARC. It’s a feature being implemented in the upcoming HDMI 2.1 specification.
Is eARC backwards compatible with ARC?
"If your TV is HDMI eARC enabled, but your AV amp or soundbar is only compatible with HDMI ARC, it’s likely you’ll get a sound - but the bandwidth restrictions of ARC will mean you won’t be able to experience the high bitrate audio that eARC can provide. So no, it's not backwards-compatible.
Some AV receivers and soundbars that don’t have HDMI 2.1 chipsets can be upgraded to support eARC, but it varies between manufacturers and models. It depends if they are using compatible hardware that can accept the necessary firmware update.
Time will tell how well integrated eARC will be, but we're hoping adoption becomes as ubiquitous as HDMI ARC seems to be now."
I never used that feature myself because it has been problematic since the very beginning of its introduction and to the present day. It is best to program ypur own universal remote control for all your devices and activities operations (eg.; Harmony), so that you have s much solider interface between all your components.
True, you need your computer and the time to program it all, but it beats CEC hundred miles per hour plus. It's better to take charge ourselves and be in control of our gear communicating to each other in perfect synch and harmony than all the flaws from CEC.
CEC, in one word is a nightmare.
True too, many people don't have the time and patience to do all the programming when they have several audio/video components in their system(s). ...Like me with (@ this moment in my main system) eight devices and ten different programmed activities. To perfectly custom all those activities takes time, a lot of time, and experimentation...trials and errors and corrections and delay values between some operations.
But when all finished only the press of a single button does everything in sync between say four devices from turning them on, adjusting the volume, selecting the proper audio, HDMI input, etc., etc., etc. No more nightmares from CEC and only one remote to rule them all (illuminated).
* I visit friends and family members where four or six remote controls cluster their tables.
It's a pain in the brain.
But they are not the type to take the time once and for all, so each time they want to perform a task of watching TV, listening to music, selecting the proper input on the receiver and TV, satellite cable box TV, powering the movie player/PC-Mac movie/music server, dropping the needle ( ;-) ) ... they need to use few remotes. No thank you very much, not for Bob. Life is enough complicated already to not complicate my entertainment on top of it.
[I want a smart car or a private chauffeur.]
And before I buy an 8K TV I'll wait for the next 3D one in 4K. Lol, I might wait a while.
ARC is more or less a moving target. For some it works, and for ...
It's much simpler than CEC though; if you introduit CEC in the ARC equation, everything goes...snowflakes from heaven or hell..for many it's hell.
eARC (new HDMI 2.1) has much more advanced features, but we are not there yet, not enough penetration as it is just starting.
We have been living with HDMI for many many years now, and it is still a problem between different manufacturers to handshake friendly. CEC is even more uncooperative.
ARC I don't use it either, but I know many who can benefit from it, same for CEC.
I'm looking forward to rollable OLED 4K TVs. They look stylish for modern people like me.