Latency Indication Protocol HDMI 2.2 Latency Indication Protocol (LIP)

What the Latency Indication Protocol is

LIP is the audio and video synchronization feature added in HDMI 2.2, the specification the HDMI Forum released on June 25, 2025. HDMI.org describes it as a way for source devices to determine latency adjustments and mitigate the differences between audio and video. The problem it addresses is lip sync: speech that trails or leads the actor's mouth. HDMI.org notes the effect gets worse when a system has several audio and video paths, and it names an AV receiver or soundbar as the usual extra hop. The HDMI Forum's release frames it the same way, as an improvement for multi-hop setups.

The feature is licensed. The HDMI 2.2 specification is available through HDMI Licensing Administrator, and the public pages give no message format, resolution, or timing ranges for LIP. This entry therefore describes what LIP is for and what the surrounding standards say, not how its messages are encoded. Anyone who claims to know the byte layout is working from the licensed document.

Why sync drifts in the first place

Every device in an HDMI chain adds delay. A TV spends time on scaling, tone mapping, and motion processing. A soundbar or AVR spends time decoding Dolby Digital Plus or TrueHD and applying room correction. heise's report on HDMI 2.2 points out that different players use different audio and video codecs with different latencies, and that those differences have not always been compensated. It names two layouts LIP is aimed at: a soundbar connected to the TV over (e)ARC while players also feed the TV, and a mix where some players go straight to the TV while others go through an AVR.

In the first layout the picture is delayed by the TV's video pipeline and the sound is delayed by the soundbar's decoder. Nothing guarantees those two delays are equal, and a source box has no way to know either one. LIP gives the source the missing information so it can shift audio or video before sending.

LIP vs the sync tools you have today

Lip-sync correction is not new. Wikipedia's HDMI feature list credits HDMI 1.3 with Auto Lip-Sync Correction, so the idea of devices reporting delay to each other predates HDMI 2.2. A technical write-up from DPL Labs describes eARC as adding automatic lip-sync compensation through metadata exchange: the sink reports its video latency, and the source adjusts audio delay to match. The differences between the two return channels are covered in eARC vs ARC.

Where those tools fall short is the multi-hop chain. A latency report between two neighbors says nothing about a third device two hops away. HDMI 2.2 places LIP at the system level, which is why the HDMI Forum calls out receivers and soundbars by name. Until LIP hardware exists, the fix is a manual audio delay setting on the AVR or soundbar (see lip-sync audio delay).

How much error is too much

ITU-R Recommendation BT.1359-1 supplies the numbers. Subjective tests put the detectability threshold at about +45 ms to -125 ms, where a positive value means sound arrives early, and the acceptability threshold at about +90 ms to -185 ms. The window between the two detectable limits is about 170 ms, and it is lopsided because viewers tolerate late sound better than early sound. For broadcast, the Recommendation holds the path from the final source to the transmitter to +22.5 ms and -30 ms, and any single digital codec to within 2 ms.

Convert that to frames. At 60 frames per second a frame lasts 16.7 ms, so 45 ms of early sound is about 2.7 frames. At 24 fps a frame lasts 41.7 ms, and the ITU's cinema reference of half a frame is about 22 ms.

A worked example, with illustrative numbers rather than measurements: a TV with its picture processing on adds 80 ms of video delay, and a soundbar adds 20 ms of audio delay. Sound is early by 60 ms, past the +45 ms detectability line. Delaying audio by 60 ms zeroes the error. Flip it, with 30 ms of video delay and 150 ms of soundbar delay, and sound is late by 120 ms, at the edge of the -125 ms line. A source that knows both numbers can fix either case without a menu.

Where LIP lives

Nowhere you can buy yet. A hwbusters report dated September 15, 2026 says no shipping GPU, console, or television speaks HDMI 2.2 and that devices are expected in 2027. ChannelNews reports the same window and says chip vendors are already sampling parts. None of the sources I fetched names a soundbar, AVR, or TV with LIP support, so this entry names none. The HDMI 2.2 bandwidth tiers and cable requirements are covered in Ultra96 HDMI cable; the sources do not say whether a product can ship LIP without the 96 Gbps tier.

Common confusions

LIP is not a lag fix. It reports and balances delay; it does not remove it. A TV's picture processing still costs milliseconds, and a console that needs the lowest input lag still wants Game Mode on. LIP's job is to keep the sound matched to whatever delay remains.

LIP is also not what you have today. If your soundbar or receiver is out of sync now, the working tools are the audio delay setting on the AVR or soundbar, the TV's own audio-sync menu, and an eARC link where both ends support it. The wider HDMI 2.2 picture, including cable tiers, is in the HDMI 2.2 entry and the HDMI cable guide.