Over an exclusive media communication at the end of September with Low Latency High-Definition Audio Codec (LHDC) technology developer, Savitech. Porta-Fi was greeted with a new logo for LHDC. The team reinforces the technology’s goal to greatly reduce the audio quality difference between wireless and wired audio devices and provide the most realistic and ultra-high sound quality.
For those of you who are new to LHDC, it is a high-quality Bluetooth codec based on the A2DP Bluetooth protocol and allows a bit-rate of up to 900 kbps compared to SBC’s bit rate of 345 kbps.
LHDC was first introduced slightly more than two years ago with the establishment of the Hi-Res Wireless Audio (HWA) Union at the Guangzhou Baiyun International Convention Center on the 1st of September 2018. HWA is the certification programme for high-sound quality Bluetooth audio products lead by smartphone manufacturer, Huawei. HWA requires manufacturers to implement LHDC as a Bluetooth codec on the Bluetooth audio product before applying for certification.
German audio manufacturer, Sennheiser introduced the IE 80S BT, its first audiophile Bluetooth In-Ear headphone during the Hong Kong High-End Audio Visual Show in August 2019 with LHDC implemented to allow the IE 80S BT to process high bit rates found in lossless music formats to achieve a performance that is on par with its wired counterpart. The IE 80S BT is HWA certified.
The Bluetooth codec was also certified by the Japanese Audio Society (JAS) in September 2019 as one of the two audio codecs for its “Hi-Res Audio Wireless” certification. The other being LDAC. Only hardware devices that implement LDAC or LHDC can apply for the “Hi-Res Audio Wireless” certification.
Most recently, China smartphone giants OPPO, Xiaomi, and vivo announced the formation of the Audio Quality Society (AQS) with the China Audio Industry Association (CAIA), the China Electronics Standardization Institute (CESI), and leading audio manufacturers Bestechnic, Edifier, HiBy, HiVi, HIFIMAN, Knowles, MediaTek, and Savitech. In alignment with the alliance’s focus on improving the audio quality of portable devices and delivering higher quality audio experiences to users, LHDC is named one of the six areas in which the alliance’s technical standards will be based.
Following the formation of AQS, LHDC is the standard that three audio bodies have based their certification upon. Since Android 10, enumeration constant symbols for LHDC, and its low-latency variant LLAC are part of the Android Open Source Project, enabling every OEM to freely integrate them into their own Android devices.
Savitech’s LHDC technology can now be differentiated into three offerings: Savitech Adaptive, LLAC, and LARC.
Savitech Adaptive is a bit rate adjustable codec, instead of being locked at a fixed bit rate, the codec dynamically adjusts the bit rate between 300 to 900 kbps according to its environment, avoiding signal dropout in environments with crowded frequency spectrums.
Low Latency Audio Codec (LLAC) is LHDC’s low-latency variant with an end-to-end latency of as low as 30ms and supports bit rates of 400 or 600 kbps. The codec also features adaptive low latency dynamically adjust the latency to ensure signal stability.
When implementing LLAC, Savitech was able to understand the impact different transmitters have on the codec. Low Latency Audio Re-Construction (LARC) is developed to address the shortcoming of low-latency lag, compensating for up to 120ms of silent shuttering. Coupled with LLAC codec, users can enjoy both the low-latency and stability that LLAC & LARC brings.
The last two years have been a difficult one for LHDC. HWA has failed to gain widespread market acceptance outside China, while Huawei’s removal of LHDC from its smartphones cannot be left unnoticed. All eyes are now on AQS, led by OPPO, Xiaomi, and vivo to chart the fledgling codec’s acceptance.