Returns a new tshark process with previously-set parameters.

async def _get_tshark_process(self, packet_count=None, stdin=None):
        """
        Returns a new tshark process with previously-set parameters.
        """
        if self.use_json:
            output_type = 'json'
            if not tshark_supports_json(self.tshark_path):
                raise TSharkVersionException("JSON only supported on Wireshark >= 2.2.0")
        else:
            output_type = 'psml' if self._only_summaries else 'pdml'
        parameters = [self._get_tshark_path(), '-l', '-n', '-T', output_type] + \
            self.get_parameters(packet_count=packet_count)

        self._log.debug('Creating TShark subprocess with parameters: ' + ' '.join(parameters))
        self._log.debug('Executable: %s' % parameters[0])
        tshark_process = await asyncio.create_subprocess_exec(*parameters,
                                                              stdout=subprocess.PIPE,
                                                              stderr=self._stderr_output(),
                                                              stdin=stdin)
        self._created_new_process(parameters, tshark_process)
        return tshark_process