HDMI ARC is the audio return channel of HDMI - "Audio Return Channel". This is typically used to operate a soundbar on the TV's HDMI input labeled "HDMI ARC". Only the audio signal is transmitted and no image. In the opposite direction, however, image and sound can be transmitted, for example if players are connected to the soundbar. In addition, control commands can be transmitted. For example, you can change the volume of the soundbar with the TV remote control.
The normal HDMI signal carries audio and video from an HDMI source to an HDMI sink. For example from a media player to a TV. The signal is transmitted from HDMI output to HDMI input. The TV only has HDMI inputs. One of these inputs often supports ARC. The audio signal from the television is then output via this - i.e. in the opposite direction - e.g. from the TV receiver or TV apps. This then supplies the AV receiver or a soundbar. The audio signal can also be converted for non-HDMI devices via the HDMI-ARC adapter.
On the one hand, HDMI-ARC simplifies the cabling between the sound system and the television. On the other hand, higher audio formats can be transmitted than via the other interfaces of a television: Modern televisions can also output Dolby Digital Plus or Dolby Atmos from streaming services.
Both designate the HDMI audio return channel or Audio Return Channel (ARC). The "e" in eARC stands for enhanced and is the newer standard. Higher multi-channel audio formats such as Dolby True-HD / Atmos or uncompressed sound such as Dolby MAT, PCM5.1 / PCM7.1 can also be transmitted via eARC. Only stereo and Dolby Digital / DTS Bitstream works via ARC. Some TVs from LG and Samsung also manage Dolby Digital Plus via ARC. That's enough for TV-internal streaming apps. But eARC also offers improved audio quality when playing Blu-ray discs, computer games and external media players. Because players such as Apple TV or Xbox only deliver Dolby Atmos uncompressed, which is why it cannot be transmitted via ARC. So if such players are connected directly to a TV with a soundbar, the TV must have eARC. If the TV only has ARC or a video projector/monitor without ARC function is used, our VAX04101 will help.