BlueTooth Audio Codecs Explained

True wireless earphones have been around for quite some years now, and you may have seen all the buzzwords including A2DP, SBC, AAC, aptX, LDAC, Hi-Res Audio Wireless. The abundance of technical terms may be confusing when you are trying to read the specs. To help you make better decisions, we are putting up a glossary to go through the terminologies quickly.

A2DP – Advanced Audio Distribution Profile
All codecs including LDAC, aptX HD are compressed and decoded under the A2DP profile. The profile also includes mandatory support for the simpler SBC codec. Since bandwidth and bitrate are limited over wireless transmission, different manufacturers come up with different codecs to transfer higher bit rate and sampling rate.

CVC – Clear Voice Capture
A microphone filtering technology that could filter away ambient noise up to 30 decibels. Simply saying, your voice will be picked up much clearer and the other end of the call will hear your voice much cleaner.

ANC – Active Noise Canceling
ANC is a technology that actively cancels the background noise by generating an inverted signal captured by a microphone. It is more commonly seen on headphones and will let you hear sound much clear eliminating the sound from the surrounding that interferes. The Apple Air Pods Pro cancels out around 20 decibels from the ambient and you will be able to hear more details in the music.

Codecs kbps ranked:
LDAC(Sound Quality Mode/Normal Mode)>aptX HD>aptX>LDAC(connection)=SBC

LDAC
Transmit High Resolution (Hi-Res) Audio at the maximum bitrate of 990kbps over Bluetooth connection. This is one of the strongest codecs up to date that allows a great leap of transmission volume over the traditional SBC codec and is supported by serious digital audio players such as the Astell & Kern KANN Ultra.

aptX
Developed by the tech marvel Qualcomm, aptX is the most popular higher resolution codecs that have a proven track record in providing stable high-quality streaming in a crowded RF environment. The series includes aptX Adaptive that can adjust its performance based on the environment, aptX HD with 576kbps max audio playback power, aptX Low Latency for gaming and more features tech-savvy would love to hear. Over 7 billion devices are estimated to be aptX capable and if you are a gamer looking for low latency headphones, you shall take a good look at aptX Low Latency tech.

aptX HD
aptX HD is an enhanced version of the well-known aptX codec, operating at a higher bitrate of 576 kbps and supporting 24-bit/48 kHz audio. This results in noticeably richer detail compared to standard aptX, making it a popular choice for compatible devices.

aptX Adaptive
aptX Adaptive, on the other hand, dynamically adjusts the bitrate between 279 and 420 kbps, offering flexibility depending on connection quality and application. With its reduced latency, it is particularly well-suited for gaming and video playback, and serves as the successor to aptX LL (Low Latency).

SBC
SBC, or subband codec, is specified by the Bluetooth Special Interest Group for the A2DP Profile. Supporting up to 345kb/s transfer (Stereo), you can use this as a reference for the minimum sample rate that is enough to simple lossy files such as MP3 (at 320kbps).

AAC
Apple’s own codec pleases the ears of many discerning audiophiles. The solution is powered by DOLBY and is widely used in Apple’s products, and is the default codec between iPhone and AirPods.

Hi-Res Audio Wireless

The certification is based on the original Hi-Res Audio standard with a special test added for TWS wireless audio devices. Wireless earphones are required to have the L/R channel’s tolerance controlled within +/-50μs, which is the equivalence of the threshold frequency human ears can pick up (20kHz).

While the specs and bitrates may look very appealing, it does not necessarily reflect the actual performance on wireless headsets or earphones. The quality of a product depends on many areas that needs sophisticated engineering inputs for example the antenna design, quality of the drivers as well as circuitry. "Hi-Res Audio Wireless" do not suggest lossless quality being transferred, but the use of higher standard codecs for superior transfer and decoding quality.