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
WMA is a proprietary audio container format of Microsoft. There are 4 codec used in WMA – WMA, WMA Professional, WMA Lossless and WMA Voice. It uses one of the four WMA codec to encode audio. WMA contains the audio file in Advanced Systems Format (ASF) format. The ASF file decides how the metadata will be encoded.