What is BSAC?
BSAC stands for bit sliced arithmetic coding that provides one of the forms of scalability in MPEG-4 audio. In order to make the bitstream scalable, BSAC uses an alternative to AAC noiseless coding module, although the other coding modules are identical to AAC. A bitstream encoded by AAC can be transcoded to an BSAC bitstream noiselessly. BSAC is capable of generating a bitstream with a precise bit rate control in the range of 16kbps to 64kbps per channel. This bit rate enables the decoder to stop anywhere between 16kbps and the encoded bit rate with a 1kbps stepsize. Through use of this scalablity, the user can experience nearly transparent sound quality at 64kbps and graceful degradation at lower bit rates. BSAC is best performed in the range of 40kbps to 64kbps, though its operating range is 16kbps and 64kbps.
