Companding is a contraction of Compression and Expansion. It may be applied to an analogue signal; it does not necessarily have to be quantised and may remain analogue and continuous-time.
Thats what i was referring to-compression,followed by quantization(uniform) and finally expansion to get the digital signal from the analog signal....So in this case the step size is unaltered while the signal undergoes non-linear distortion....And in case of non-uniform quantization the signal is unaltered while the step size varies as the signal amplitude varies....Right????Did i miss anything????