
One of the devices transmits in even numbers of slots, the other-in odd numbers.

The time is divided into 625 microsecond intervals, called slots.

You may wonder why we need a codec in the first place, if Bluetooth has EDR, which allows you to transfer data at 2 or 3 Mb/s while uncompressed two-channel 16-bit PCM requires only 1.4 Mb/s? Bluetooth Data TransferThere are two types of data transfer in Bluetooth: Asynchronous Connection Less (ACL) for asynchronous transfer without establishing a connection, and Synchronous Connection Oriented (SCO), for synchronous transfer with connection establishment.ĭata transmission uses time-division scheme and changes frequency channel for each transmitted data packet (Frequency-Hop/Time-Division-Duplex, FH/TDD).


Browsers are able to execute audio encoders compiled to WebAssembly from C using emscripten, and they won't even lag.aptX is not as good as the advertisements say.Headphones have their own per-codec equalizer and post processing configuration.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. They do not tell about all the features, and often publish the same false information. 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.īluetooth device manufacturers rarely disclose detailed product specifications, and Bluetooth audio articles on the Internet are contradictory and sometimes incorrect.
