Super Bit Mapping (SBM) is a noise shaping process, developed by Sony for CD mastering.1
Sony claims that the Super Bit Mapping process converts a 20-bit signal from master recording into a 16-bit signal nearly without sound quality loss, using noise shaping to improve signal-to-noise ratio over the frequency bands most acutely perceived by human hearing.2
Audible quantization error is reduced by noise shaping the error according to an equal-loudness contour.3
This processing takes place in dedicated hardware inside the recording device. A similar process is used in Sony's DSD to PCM conversion and is called SBM Direct.
References
References
- Maes, Jan; Vercammen, Marc; Baert, Luc (2001). Digital audio technology: a guide to CD, MiniDisc, SACD, DVD(A), MP3 and DAT (4th ed.). Focal Press. pp. 60–63. ISBN 978-0-240-51654-7.
- "Super Bit Mapping Technical Overview" (PDF). Sony. Retrieved 15 January 2013.
- US 5204677, "Quantizing error reducer for audio signal"