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
A file with the CDDA file extension is a CD Digital Audio file that stores audio in the AIFF format. CDDA files are normally seen only when audio files have been ripped from an audio CD that uses the CD Digital Audio specification. This is most often done through the Apple iTunes program with the Audio CD burn option.