Codec stands for encode/decode. Because raw audio data is too large to transmit and stream in real-time, audio must be compressed (encoded) using a codec before it's streamed over Bluetooth A2DP (Advanced Audio Distribution Profile). Once the encoded audio is recevied by the output device, it is decoded before it can be played. Each source and output device supports its own combination of codecs and generally the highest performing common codec between the source and output device will be used.
Codecs can vary in sound quality, processing power, and latency, so they're an important consideration when choosing a set of bluetooth audio devices. Below are a list of commonly used codecs for Bluetooth A2DP streaming audio.
|Name||Max Bitrate||Bit Depth||Max Frequency||Introduced||# of devices supported||# of accessories supported|
|aptX LL||352 kbps||16 bit||44.1 kHz||2016||0||3|
|aptX HD||576 kbps||24 bit||48.0 kHz||2016||645||15|
|LDAC||990 kbps||24 bit||96.0 kHz||2015||500||6|
|AAC||264 kbps||16 bit||44.1 kHz||2015||542||37|
|UHQ||-||32 bit||384.0 kHz||2015||2||2|
|aptX||352 kbps||16 bit||48.0 kHz||2009||1001||29|
|SBC||320 kbps||16 bit||48.0 kHz||2003||6718||66|