What is HDMI-eARC/HDMI 2.1 and How Does it Differ from HDMI-ARC?

HDMI-ARC

• HDMI (High Definition Multimedia Interface) has gone through many different iterations/versions since its debut in 2004. HDMI version 1.4 brought the advent of HDMI-ARC (Audio Return Channel). Prior to the invention of ARC, HDMI could only transmit audio/video "one way". "One way" meaning, think of the audio and video signal as a one way street. It can only go one way. With the addition of HDMI-ARC, the audio/video now works as a two way street. It can transmit video, while also simultaneously outputting audio to the sound bar (or whatever external sound device the customer may have) via the TV's HDMI-ARC functionality/port. 
  
  
  • For Example: Picture this - connected to your TV, you have an Xbox, an Apple TV and a Fire TV stick. All devices are plugged into separate HDMI ports on the TV. Before ARC, you would need all of these devices plugged into the TV and then have a separate cable (optical, RCA component etc.) supplying audio to the sound bar or A/V receiver.
     
    Now, with ARC, the devices can be plugged into the sound bar's or A/V receiver's HDMI ports. Then, a single HDMI cable (plugged into an HDMI-ARC port) will carry the video to the TV, and the TV will then return the audio back to the sound bar or A/V receiver via ARC. There is no longer any need for a separate audio cable. A single HDMI cable (plugged into ARC compatible TV's/devices) will carry the video to the TV and then return the audio to the system the customer is using.
    
    
    
    Here is another image, for additional clarification, that shows the "Before" and "After" of HDMI-ARC:
    
    

HDMI-eARC

• Now, the most current version of HDMI is HDMI 2.1. This version has brought the addition of 'eARC'. To put it as simply as possible, this new eARC function has built on the foundation of what ARC already created and has now made it stronger and more robust. It essentially raises the bandwidth and speed of the signal transmission.

• This increase in speed and bandwidth allows HDMI to carry higher qualities of audio, which includes the new object-based surround technologies, such as Dolby Atmos and/or DTS:X.
• It also allows for higher video qualities; 4K and 8K videos will be able to transmit a higher frame rate and overall resolution through HDMI 2.1. However, we do not need to focus on the video aspect, we obviously will just focus on the audio benefits of HDMI 2.1/eARC.