In fact, as early as the Bluetooth 2.0 / 2.1 era, the Bluetooth transmission rate has reached 2.1 Mbps, enough to meet the transmission of high-quality audio. However, in the Bluetooth audio transmission, whether it is the early Bluetooth 2.0 / 2.1, or the now popular Bluetooth 4.0, the same A2DP protocol is used
Because the A2DP protocol greatly limits the transmission bandwidth, the audio signal needs to be effectively compressed to ensure real-time playback at the receiving end, which has a variety of different codec solutions in Bluetooth audio equipment.
There are three main Bluetooth audio codec solutions: SBC, AAC and apt-X. Among them, SBC is an ancient, but still the most common Bluetooth audio codec scheme, AAC and apt-X are relatively new, and some improvements have been made in the SBC scheme. In theory, the sound quality is better than the SBC scheme. It should be noted that although apt-X claims to be a "CD-level" audio codec solution, in actual use, apt-X is certainly much better than the ancient SBC, but there is still a certain distance from the "CD-level" transmission. distance. In addition, apt-X needs to support both the transmitting device and the playback device. If you want to use apt-X, in addition to needing a mobile phone that supports apt-X, you should also check whether the speaker itself supports it before buying a Bluetooth speaker.
If you want to name these three codec schemes, under normal circumstances, apt-X is better than AAC and better than SBC, and there is still a clear gap compared to traditional wired audio transmission. However, if this gap is placed in a small Bluetooth speaker, the impact on sound quality is far less than theoretically.