* This function looks at the first \p WAV_HEADER_SIZE bytes of the input queue
* of the btrn of \a cwc. If they look like a wav header, the function extracts
* the information of interest and swallows this part of the stream. Otherwise
* This function looks at the first \p WAV_HEADER_SIZE bytes of the input queue
* of the btrn of \a cwc. If they look like a wav header, the function extracts
* the information of interest and swallows this part of the stream. Otherwise
*
* Once the first part has been processed this way, the state of the instance
* changes from \p CWS_NEED_HEADER to \p CWS_HAVE_HEADER or \p CWS_NO_HEADER.
*
* Once the first part has been processed this way, the state of the instance
* changes from \p CWS_NEED_HEADER to \p CWS_HAVE_HEADER or \p CWS_NO_HEADER.