This article is also available in Russian / Эта статья также доступна на русском языке
The mass market of smartphones without the 3.5 mm audio jack changed headphones industry, wireless Bluetooth headphones have become the main way to listen to music and communicate in headset mode for many users.
Bluetooth device manufacturers rarely disclose detailed product specifications, and Bluetooth audio articles on the Internet are contradictory and sometimes incorrect. They do not tell about all the features, and often publish the same false information.
Let's try to understand the protocol, the capabilities of Bluetooth stacks, headphones and speakers, Bluetooth codecs for music and speech, find out what affects the quality of the transmitted audio and the delay, learn how to capture and decode information about supported codecs and other device features.
- SBC codec is OK
- Headphones have their own per-codec equalizer and post processing configuration
- aptX is not as good as the advertisements say
- LDAC is a marketing fluff
- Voice audio quality is still low
- Browsers are able to execute audio encoders compiled to WebAssembly from C using emscripten, and they won't even lag.