1. A computer system for coding and decoding digital signals by vector quantization at variable rate defining a variable resolution, comprising: a computer readable medium storing a dictionary comprising: codevectors of variable dimension; and inter-embedded sub-dictionaries of increasing resolution of a given dimension, wherein each sub-dictionary comprises a union of a) a first set consisting of codevectors constructed by inserting, into codevectors of dictionaries of lower dimension, elements taken from a finite set of real numbers according to a finite collection of predetermined insertion rules, and of b) a second set consisting of codevectors that may not be obtained by insertion into codevectors of lower dimension of the elements of said finite set according to said collection of insertion rules.