Continuously Variable Slope Delta modulation is a voice coding method. It is a delta modulation with variable step size (adaptive delta modulation), first proposed by Greefkes and Riemens in 1970
SDII (Sound Designer II, sometimes seen abbreviated as SD2) is a monophonic/stereophonic audio file format, originally developed by Digidesign for their Macintosh -based recording/editing products. It is the successor to the original monophonic Sound Designer I audio file format.