The Bluetooth Special Interest Group (SIG) has specified the low-complexity, subband codec (SBC) in the Advanced Audio Distribution Profile (A2DP).[1] SBC is an audio encoder and decoder to connect Bluetooth high quality audio devices like headphones or loudspeakers. It can be also used on the Internet.[2] It uses 4 or 8 subbands, an adaptive bit allocation algorithm in combination with an adaptive block PCM quantizers. Frans de Bont has based the SBC audio codec on his earlier work,[3] and – in parts – on the MPEG-1 Audio Layer II standard. In addition, the SBC is based on the algorithms described in the EP-0400755B1.[4]. The patent owners wrote that they allow the free usage of SBC in Bluetooth application, with the view to boost the use of this technology. All applications outside Bluetooth are however not free. The patent expired June 2, 2010.
The A2DP test specification (V1.0) contains a reference implementation of the encoder and decoder for the SBC codec. A Linux implementation is available at BlueZ - The linux Bluetooth Stack.