LHDC (codec)

Low Latency High-Definition Audio Codec (LHDC) is an audio codec technology developed by Savitech. LHDC allows high-resolution audio streaming over Bluetooth. It is a high-quality Bluetooth codec based on the A2DP Bluetooth protocol and allows a bit-rate of up to 900 kbit/s compared to SBC's bit rate of 345 kbit/s.

LHDC is an alternative to Bluetooth SIG's SBC and LC3 codecs. Its main competitors are Qualcomm's aptX-HD/aptX Adaptive, Huawei 's L2HC and Sony's LDAC codec.

Starting from Android 10, enumeration constant symbols for LHDC and LLAC are part of the Android Open Source Project, enabling every OEM to integrate this standard into their own Android devices freely. Older versions of Android require LHDC/LLAC enumeration constant symbols to be implemented by the smartphone manufacturers or Android app. Android apps with this type of LHDC support include Savitech's Hi-Res BT Player, FiiO Music, HIFIMAN Music and DA&T Audio.

LHDC
LHDC supports bitrates of 400/560/900 kbit/s, bit-depth of up to 24 bit and sample rate of up to 96 kHz.

The first Smartphone to support LHDC was the Huawei Mate 10.

On 17 September 2019, the Japan Audio Society (JAS) certified LHDC with their Hi-Res Audio Wireless certification. As of June 2024, the codecs certified by the JAS to bear the Hi-Res Audio Wireless logo are LHDC, LDAC, SCL6, LC3plus, SHDC, and aptX Adaptive.

LLAC
Low Latency Audio Codec (LLAC) is also called LHDC LL. It is based on the high definition wireless audio technology from LHDC, but designed for low latency and features an auto-detect gaming mode. Savitech claims LLAC has end-to-end latency of around ~30ms. LLAC supports bitrates of 400/600 kbit/s, bit-depth of up to 24 bit and sample rate of up to 48 kHz. LLAC has no hardware requirement for the transmitter.

The first Smartphone to support LLAC was the Huawei P30.

Hi-Res Wireless Audio (HWA) Union
On 2 September 2018 the Hi-Res Wireless Audio (HWA) Union was formed to promote LHDC adoption. Also known as the HWA Alliance. The HWA Union Board of Directors includes:


 * AKM
 * China Electronics Technology Group Corporation
 * Cirrus Logic
 * Edifier
 * Guoguang Electric
 * HiFiMAN
 * HiVi
 * Huawei
 * Institute of Acoustics of the Chinese Academy of Sciences
 * Savitech
 * iriver
 * Sennheiser
 * Taihe Music Group

Other HWA Union members include:


 * ams AG
 * Astell & Kern
 * Audio-Technica
 * Aukey
 * Cayin
 * Cozoy
 * Coolhere
 * Colorfly
 * DA&T
 * DA-ART
 * DUNU
 * FiiO
 * Fostex
 * Haylou
 * HiBy
 * infly
 * iEAST
 * Liesheng
 * Musiland
 * NFJ FX-AUDIO
 * OC Studio
 * Onkyo
 * Pioneer
 * ProStereo
 * QCY
 * Questyle Audio
 * Quloos (QLS HiFi)
 * Radius
 * Shanling
 * S.M.S.L
 * TASCAM
 * TEAC
 * TempTec
 * Tecsun
 * TiinLab
 * Topping
 * Tube Fan Audio
 * VMN
 * xDuoo
 * YULONG Audio
 * 1MORE

HWA Certification
On March 27, 2018, Huawei and Savitech announced the Hi-Res Wireless Audio (HWA) Certification. Platinum HWA Certification requires frequency response over 40 kHz, THD+N<-90 dB, SNR>110 dB, and playback using the at least 24bit/96 kHz. Gold HWA Certification requires frequency response over 20 kHz, THD+N<-80 dB, SNR>100 dB, and playback using the at least 24bit/48 kHz.