 Conversely, if a conventional CD is placed into an SACD player, the laser will read the disc as a CD since there is no SACD layer.SACD audio is stored in Direct Stream Digital (DSD) format using pulse-density modulation (PDM) where audio amplitude is determined by the varying proportion of 1s and 0s.This contrasts with compact disc and conventional computer audio systems using pulse-code modulation (PCM) where audio amplitude is determined by numbers encoded in the bit stream.