[Home Theater Network HDAV.com.cn] 2016-2017, the audio industry ushered in the era of rapid change under the promotion of smart phones. With the elimination of 3.5mm headphone jacks and the popularity of streaming music, mobile phone manufacturers have become increasingly popular. The rise of Bluetooth wireless audio products has brought us a more convenient and easy listening experience. At the same time, as everyone's pursuit of sound quality is getting higher and higher, higher-level Bluetooth wireless transmission technology is also coming.
First of all, it is clear that the Bluetooth transmission protocol and the Bluetooth codec technology are two relationships. Bluetooth transmission audio mainly relies on the A2DP protocol, which was established in the early days of the Bluetooth standard. At that time, the current situation was not taken into account, and the amount of data during transmission was limited, so that the audio data could only reach about 328 kbps.
Although the higher Bluetooth 4.X transmission protocol can theoretically bring more stable transmission and low power consumption, the sound quality related is its Bluetooth codec technology. Therefore, since the A2DP protocol cannot be changed, if you want to improve the sound quality of Bluetooth, you can only start from the optimization of compression and encoding. Based on this, the SBC, AAC, and APT-X codec specifications are generated.
Among the three specifications, SBC is the most common, and basically all smartphones, Bluetooth headsets and speakers are supported. The maximum allowable rate of SBC is mono 320kbit/s, dual channel 512kbit/s audio transmission, the algorithm is not good enough, so the sound quality performance is not ideal.
AAC is currently mainly used by Apple. iPhone, iPad and other devices support AAC. Although the supported rate is not much better than SBC, the algorithm is better, the sound quality is much better than SBC, and the difference is heard by ordinary people. .
Then there is APTX: it is a lossless format for Bluetooth transmission. It is promoted by CSR. Now, after being taken over by Qualcomm, APTX is very popular in Android mobile phones.
Finally, Sony introduced the LDAC codec technology in 2015. LDAC technology maintains its maximum bit depth and frequency response range, enabling high-quality transmission even at 96 kHz/24 bit audio.
LDAC's codec technology Compared with the traditional Bluetooth audio transmission technology, before transmitting LPCM audio, the first thing to do is to compress the high resolution audio to 44.1 kHz/16 bit CD quality, and then transfer it through 328 kbps. In the case of two large loss of information, the final quality is far from the quality of the CD.
Of course, it should be noted that the LDAC transmits the same kind of lossy audio, not lossless, so Sony does not deny this. Sony said that the audio after transmission is no longer "high resolution", but it is called "high quality" audio. However, the official claims that even the loss of information caused by the transmission of LDAC is still much less than the traditional Bluetooth transmission.
So if you buy a Bluetooth audio product such as a Bluetooth speaker, please forget the word "Bluetooth Protocol". First of all, look at the support for ATP-X coding specification or LDAC specification. Since you have decided to buy Bluetooth audio products, you can upgrade it. feel the ear, why buy the wrong ears so that suffers it? (B rice transferred from the author: air coins)
More fresh and fun home theater information, please pay attention to home theater network http:// (WeChat: cnhifi), the country's most influential home theater audio player interactive media website.
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