People always believe the sound quality of wired headphones is always better than that of Bluetooth headphones. Actually, after Bluetooth 3.0, the transmission bandwidth has been increased to more than 24Mbps, which is much higher than the CD lossless music (1.41Mbps). So we have already had opportunities to have better listening experience with TWS earphones/earbuds.
Many people are asking me what are SBC, ACC, aptX, LDAC and LHDC. They completely have no idea about them. What are them and are they the key features for us to choose TWS earbuds/earphones? This time, I will reveal and tell more about them.
1. SBC(Sub-band coding)
The earliest transmission format should be SBC. SBC is an encoding format mandated by the A2DP (Advanced Audio Distribution Profile) protocol. All Bluetooth devices should support this protocol. So all Bluetooth audio chips support this protocol. I couldn’t find the specific parameters of the bit rate of the SBC code during transmission. According to the information given on the official website of Sony, it is 328Kbps, 44.1KHZ.
2. ACC(Advanced Audio Coding)
ACC is a technology provided by Dolby Laboratories for the music community. It is an encoding algorithm with a high compression ratio. In actual experience, it is believed that under the same code rate, music with .acc listens better than with .mp3. You can find a lot of ACC musics from Apple Music.
Therefore, the current iPhone audio transmission format is also acc format. Although the bit rate of ACC is equivalent to SBC, the actual experience is much better than SBC.
APTX is CSR’s patented coding algorithm. After being acquired by Qualcomm, APTX has been promoted in Android devices. The official website is http://www.aptx.com/. There are a lot of supported devices on the official website.
According to the official website, there are three child types: aptX, aptX HD and aptX Low Latency. According to the names, it can be considered that they are traditional aptX, high-quality aptX (estimated to increase the bit rate) and low-time delay aptX (mainly for gaming).
The Qualcomm® aptX™ audio coding algorithm originated in the late 1980s at Queen’s University Belfast. This innovative work was focused on bit rate reduction and achieved significant bit rate efficiencies while preserving audio quality.Quoted from www.aptx.com
aptX has been the best kept secret of the professional audio industry, used by major public broadcasters and film studios around the world. Now available on leading consumer devices, aptX enables music lovers to enjoy the rich listening experience that aptX delivers.Quoted from www.aptx.com
aptX algorithm has high bit rate efficiency while maintaining high audio quality. As a professional wireless audio transmission solution, aptX is widely used in public broadcasting and movie audio, and now it is finally put in consumer products.
Therefore, aptX’s transmission code rate is not estimated to be high, which may be similar to SBC and ACC. But due to efficient encoding, the sound remains more details and the actual listening experience is better than SBC and ACC.
LDAC is a disruptive wireless audio coding technology developed by Sony. It shows firstly at the 2015 CES. Compared with the traditional standard Bluetooth encoding and compression system with a transmission rate of 328kbps, LDAC technology can reach a maximum of 990 kbps, which is more than three times higher than the standard Bluetooth using A2DP protocol and SBC encoding (328Kbps, 44.1KHz).
The biggest feature of LDAC is that it guarantees the wireless audio transmission speed. When this is implemented into the actual music listening experience, the sound is fuller. Due to the lack of speed, the traditional SBC Bluetooth transmission appears lacking, just like listening to a voice without emotion. With the development of LDAC technology, sound density and strength appear higher. The music details are much richer, and the low frequencies also appear deeper.
The earliest version of LHDC is a private Bluetooth audio encoding protocol developed by Savitech.
The basic idea and the actual experience of LHDC are actually very similar to Sony’s LDAC. Huawei is a pioneer of its application, and they already involved LHDC encoding into HWA standard, facing the future.