Difference between delta modulation and differential PCM Delta modulation encodes the difference between a sample and the previous sample in only one bit.
Differential PCM encodes the difference between a sample and its predicted value. Is this difference encoded in one bit or more than one bit? If encoding is done in more than one bit, what is the advantage of differential PCM over delta modulation?
Since the encoded values are differences between original values, the values are relatively small values and they are in general distributed as small positive and negative values around zero. This helps to further compress the data by using some algorithm that can use shorter codes to represent smaller values that appear frequently in the data, and longer codes for larger values that appear less often.