In this paper, a G.729EV codec is implemented, in real-time, using ARM9E-J?core. The assembly code for G.729EV is developed through the serial process of C code optimization, cross compile, and assembly code optimization. C code is trimmed on Visual C++ platform. Cross compile and assembly code optimization are performed on CodeWarrior with ARM compiler. The implemented S/W is evaluated, using 30 test vectors given by ITU-T, to prove the bit-exactness.