Fix audio packets wrapping

* Add return wrapping status enum :
    * success,
    * error,
    * waiting for data.
* Feed the wrapper with data when needed to complete the writing.
* Fix the audio output frame size problem when transcoding.
the name is incorrect if I understood correctly.
I hink you need to name it something like: lastProcessDataSize
Are you agreed ?
And you need to re-init frames when it changes (the case on the last packet).