VDVI is a variable-rate version of DVI4, yielding speech bit rates of between 10 and 25 kb/s. It is specified for single-channel operation only. It uses the following encoding:
DVI4 codeword VDVI bit pattern __________________________________ 0 00 1 010 2 1100 3 11100 4 111100 5 1111100 6 11111100 7 11111110 8 10 9 011 10 1101 11 11101 12 111101 13 1111101 14 11111101 15 11111111