Wrapping a bidirectional stream in NodeJS

I would like to wrap a socket into another object which:

transforms output - e.g. turning strings into Base64 transforms input - e.g. turning Base64 into strings

(Note: my use case is not Base64 but is isomorphic to that and would significantly complicate the question.)

It is trivial to do this in the two direction separately - e.g. pipe socket into a Base64 decoder and write into a Base64 encoder which pipes into the socket.

I would like to generate a single new object from a socket, which could be written to and read from (via data events), yet perform the required transformations for both directions.

The solution needs to support Node 0.8.X and 0.10.X.