What does the "code" marked on the wireless headset mean?

What does the "code" marked on the wireless headset mean? There will be fewer pits if you understand it.

Bluetooth headsets now also refer to wireless headsets in general. With the popularity of various wireless devices in the past two years, Bluetooth technology has received a new improvement. When a hundred flowers bloom, it is destined to be uneven. Various manufacturers are everywhere in the publicity. For example, they will always indicate that they support xxx encoding, such as common aptX, AAC, SBC, etc. What do these encodings mean? What is the use of supporting these codes? Manufacturers are so loud, but as a user, the sound quality and delay actually experienced are the real feelings. The following will give you a detailed introduction to what these encoding formats are. After understanding it in minutes, you can avoid being trapped.
SBC
SBC is the most basic encoding format, which is a mandatory encoding format stipulated by the A2DP (Bluetooth Audio Transmission Protocol) protocol. The bit rate of SBC is extremely low, similar to that of high-quality MP3. However, because the Bluetooth transmission intermediate device needs to be transcoded, the details will be lost every time it is transcoded, resulting in SBC's hearing experience will be worse than the original MP3. This kind of encoding not only has poor sound quality and high latency, but all Bluetooth will support this protocol.

ACC
ACC is a technology provided by Dolby Laboratories for the music community. It is a coding algorithm with a high compression ratio. In actual experience, it is believed that at the same bit rate, ACC has a better listening experience than MP3, and there are many ACC audio on Apple. Therefore, the current iPhone audio transmission format is also acc format, the bit rate is equivalent to SBC, but it should be noted that the Bluetooth AAC codec does not directly transmit the AAC raw data stream, so the use of Bluetooth AAC cannot get the complete AAC format. Sound quality, but it is still much better than SBC.
aptX
aptX is a patent of CSR company. After CSR was acquired by Qualcomm, aptX was quickly promoted in Android phones. There are three types of aptX: traditional aptX, high-quality aptX-HD and low-latency aptX-LL. Thanks to the efficient encoding, aptX can retain more sound details. The actual listening experience is better than SBC and AAC, and it can almost reach the CD-level listening experience, and no matter which aptX is used, the delay is much lower. .
LDAC
LDAC is a dedicated encoding format for Sony, which increases the channel very simply and rudely. On devices that support LDAC, the Bluetooth communication bit rate is close to 1M. This also allows it to have a very high transmission rate, which makes it possible to transmit lossless music. Of course, the transmission format of this kind of almost proprietary protocol also leads to almost only Sony's own equipment compatible. But there is no doubt that LDAC has achieved a great improvement in the transmission rate, making the transmitted audio quality higher, and the listening experience is naturally the best, but the delay problem still exists.

LHDC
LHDC is owned by Taiwanese manufacturer SAVITECH. This technology allows the transmission of 24bit/96kHz streaming audio (also known as high-resolution audio) through a Bluetooth connection up to 900kbit/s. Following Sony’s LDAC agreement, LHDC has become the second Bluetooth high-quality standard certified by the Japan Audio Association to reach the Hi-Res Audio Wireless standard. The HWA used by Huawei is based on this encoding format.

Although LDAC and LHDC have good sound quality, they are still used less. Only some Huawei phones support HWA, Xiaomi Mi 9 Pro supports LHDC, and there are fewer headsets supported. At the same time, the delay problem is still not solved very well.
At present, the most widely used high-quality encoding is the aptX series encoding. The sound quality and LDAC brought by aptX-HD are at the same level, and it has better performance in terms of stability. And aptX-LL has not yet been popularized. Although there is headset support, there is no mobile phone support. However, the price of earphone devices that can be supported by these two encodings is relatively high, so there is a balanced performance in terms of delay and sound quality, and the more stable aptX has become the most popular choice.

SBC, AAC and aptX are the three most common audio codecs, and the supported audio devices are relatively affordable compared to the above. As the most basic encoding format, SBC should be supported by all Bluetooth headsets. AAC is relatively better, but still not much improved. aptX not only has better audio resolution, but also the delay is greatly reduced, so when buying a Bluetooth headset, it is best to choose the one that supports aptX.​​​