eARC vs ARC Enhanced Audio Return Channel vs Audio Return Channel

What ARC and eARC do

The Audio Return Channel arrived in HDMI 1.4. HDMI.org describes it as letting a TV, over a single HDMI cable, send audio "upstream" to an A/V receiver, which removes the separate S/PDIF cable. eARC extends the idea in HDMI 2.1: audio that originates from cable, satellite, streaming or source devices connected to the TV is sent to an AVR or soundbar through one HDMI cable. DPL Laboratories adds the mechanics. ARC reuses the HEAC pair on pins 14 and 19, its signaling derives from the IEC 60958 standard that governs S/PDIF, and it is switched on through CEC. eARC handles discovery and capability reporting on its own data channel, so it can work even where CEC is disabled.

Bandwidth: about 3 Mbps vs 37 Mbps

DPL puts ARC at a data rate of approximately 3 Mbps, enough for up to 5.1 channels of encoded sound, with timing built around 44.1 kHz and 48 kHz sampling. HDMI.org says eARC supports up to 192 kHz sampling and 24-bit depth with a maximum audio bandwidth of 37 Mbit/s. DPL specifies a unit interval of 27 ns for the eARC link and a control subchannel running typically under 1 Mbps.

The arithmetic shows why the gap matters. Raw PCM payload is channels x sample rate x bit depth. Stereo at 48 kHz and 24 bits is 2.304 Mbps and just fits ARC's budget. A 5.1 mix (6 channels) at 48 kHz is 6.912 Mbps, over twice what ARC carries. Eight channels at 192 kHz is 36.864 Mbps, and so is 32 channels at 48 kHz, both within a hair of eARC's 37 Mbit/s ceiling before framing overhead. Compressed Dolby Digital Plus at 768 kbps is 26% of ARC's 3 Mbps and 2.1% of eARC's 37 Mbps. These are my calculations from the published figures, not measured link rates.

The two channels also share copper. The HEAC pair on pins 14 and 19 is normally reserved for the optional HDMI Ethernet Channel, which HDMI.org rates at up to 100 Mb/sec, and ARC reassigns that pair to carry audio instead. DPL says the eARC pair is held to a controlled impedance normally centered around 100 ohms, in the same cable as the FRL video lanes.

eARC vs ARC head to head

Formats are the headline difference. ARC carries compressed multichannel audio such as Dolby Digital, DTS and MPEG-2 AAC and does not support uncompressed high-bitrate audio such as Dolby TrueHD or DTS-HD Master Audio (DPL). HDMI.org lists eARC support for uncompressed 5.1 and 7.1, 32-channel uncompressed audio, DTS-HD Master Audio, DTS:X, Dolby TrueHD and Dolby Atmos. Control differs too: ARC is switched on through CEC, while eARC manages discovery on its own. An eARC device plugged into a non-eARC partner falls back to ARC through its discovery sequence (DPL).

Cables are less strict than the marketing suggests. HDMI.org says all HDMI cables support Audio Return Channel when both ends are ARC-enabled. For eARC, HDMI.org says either a Premium High Speed cable (up to 18 Gbps) or an Ultra High Speed cable (up to 48 Gbps) can provide the best audio performance, so choose the cable by the video your system needs. Length adds a wrinkle. In hybrid active optical cables the eARC pair remains copper while the video pairs convert to optical, and DPL says power irregularities on the +5 V rail in long active cables can prevent eARC mode from engaging. See Ultra High Speed HDMI cable.

Atmos over ARC: the usual confusion

Atmos does work over plain ARC when it rides inside Dolby Digital Plus. Sonos says its Arc, Arc SL, Arc Ultra and Beam (Gen 2) play Atmos via Dolby Digital Plus or Dolby TrueHD, and that they must be connected to HDMI ARC or HDMI eARC to play any Atmos content. Netflix says its tests found the point where extra quality is imperceptible is 640 kbps for Dolby Digital Plus and 768 kbps for Atmos, which fits inside ARC's budget (Engadget). Lossless TrueHD Atmos does not: Sonos lists Dolby TrueHD and Atmos via TrueHD on the Arc Ultra with an eARC connection required. So a TV's built-in streaming apps can reach a soundbar over ARC, while a UHD Blu-ray player routed through the TV needs eARC. See DD+ JOC, Dolby TrueHD and ARC.

Which products support it

LG's 2026 C6 lists four HDMI inputs that support 4K 120Hz, eARC, VRR, ALLM, QMS and QFT, but its HDMI Audio Return Channel entry names one port: eARC on HDMI 2. Plug the soundbar into the wrong input and you lose the return path. Sonos says the Arc Ultra connects to the TV's HDMI eARC/ARC port with the included HDMI cable. A source plugged straight into the receiver, such as an Apple TV 4K, bypasses the return channel entirely.

Common confusions

An HDMI 2.1 TV is not guaranteed to have eARC on every port, as the C6 shows, and an ARC label on a port does not mean eARC. A mismatch at either end drops the link to ARC. Lip-sync is a separate feature: HDMI.org says LipSync, introduced in HDMI 1.3, keeps audio matched to video whether it travels upstream or downstream. For the cable tier, see our HDMI cable guide, and for the receiver side see Dolby Digital Plus vs TrueHD streaming and the receiver match tool.