What is HDMI ARC and eARC (how TV sound reaches a soundbar)?
In one sentence: A lane in an HDMI cable that carries sound back from the TV to a soundbar or receiver; the enhanced version is wide enough for full-quality surround sound.
A little more
HDMI cables normally carry picture and sound one way: from the console or player into the TV. ARC (Audio Return Channel) lets the TV send sound back the other way down the same cable to a soundbar or AV receiver, so a TV's own apps can play through the soundbar without a separate audio cable. It only works on the HDMI port labelled ARC or eARC, on both ends.
Plain ARC is narrow, about enough for compressed surround sound. eARC (enhanced ARC, from HDMI 2.1) has a much wider lane, so it can pass full-quality, uncompressed surround and Dolby Atmos formats from films and streaming apps. If the soundbar is silent, check both ends use the ARC/eARC port, HDMI-CEC (the TV maker may call it Anynet+, Bravia Sync, SimpLink or similar) is on, and the TV's sound output is set to the HDMI device. A soundbar plugged in between a console and the TV also edits the screen's EDID list, which can hide 4K 120 Hz or HDR modes.
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