PCM Audio interface


Hi guys, I am wanting to develop a handsfree audio kit to be used with the WMP100. I see that I can go with either the analogue or digital interface. Digital is the route that I am wanting to go, but there is not much information on the PCM audio interface and what types of devices can interface to the module.
Does anyone have some information for me that will lead me in the right direction for selection of an audio codec chip.
Your assistance is appreciated in advance.