ActiveX to Convert Audio to and from AMR and VOX

I need to have an ActiveX OCX or DLL developed that will convert from AMR and VOX to WAV and from WAV to AMR and VOX, with parameters to define the settings for the output (in the case of AMR and VOX). I'm really looking for someone that has already developed these capabilities and has it implemented somewhere. That is, something that can just be ported into an ActiveX for a quick turn-around and an already tested/reliable solution. Please attach information on your already developed solution when posting, or an EXE example that performs the task. Thanks.