Bluetooth problems Part 2
As a result, SBC starts to sound even worse in the context of more “advanced” codecs.
However, there is an interesting point: it can sound even better than AptX HD with a bit rate of 576 kbps. How is that? It’s simple: as I wrote earlier, this codec can be scaled within a very wide range, and its theoretical maximum is just over 1.5 Mbit / s, that is, it can even pass CD Audio without compression! Of course, in fact, in our noisy 2.4 GHz band, that speed is only possible in dreams, and not all headphones support it. However, the vast majority of solutions on the market are capable of working with SBC at a bit rate of 400 to 600 Kbps.
As a result, this is enough for psychoacoustics to stop cutting off frequencies, and in theory SBC starts to introduce even less distortion into the sound than Qualcomm’s newer codecs (yes, AptX belongs to them). But here everything was spoiled by the drivers: neither in Windows, nor macOS, nor iOS, you can in any way change the standard bitrate of 328 kbps upwards. The so-called SBC HD with a higher bit rate is available only for Android with LineageOS custom firmware. So, as I said initially, SBC wasn’t “killed” by a bad implementation – it was killed by bad drivers, and this codec itself is very good.
In 2020, we still cannot hear stereo sound through Bluetooth when we use the headset microphone
I think many users have found that when answering a call with wireless headphones, the sound quality drops significantly. What happens is that the headphones go into headphone mode (HFP, Hands-Free Profile). In this mode, they can transmit sound from the microphone of the headphones to the smartphone, but the sound of the smartphone is output only in mono. Of course, this is enough for a conversation – you don’t need stereo for clear speech understanding. But in 2020, we are often used to talking and listening to music or playing at the same time, and in this case, obviously, flat mono sound with low quality spoils everything.
Therefore, if you want to listen to music in stereo and chat at the same time, you will have to use an external microphone (for example, a smartphone). In this case, the standard profile A2DP (Advanced Audio Distribution Profile) will be used with at least SBC (or other “full” codec). But, of course, you will not have freedom of movement. This limitation was logical in the early 2000s, when Bluetooth sound was in its infancy – headphones were used only for communication, and the weak processors in the headphones were simply not enough to simultaneously work with stereo sound and a microphone.
But in the modern world, where headphones support complex mathematical codecs, such as AAC or LDAC, with noise cancellation and other chips, it was quite possible to expand the A2DP profile to the ability to receive and transmit sound in stereo.
