Switched metadata IO to greenlet

        # Stream for buffering capture data

        self.stream = io.BytesIO()

        # Event to notify when the stream has finished writing to disk

        #self.file_ready = Event()

        self.file_ready = gevent.event.Event()

        # Access lock for the disk file

        self.lock = gevent.lock.BoundedSemaphore()

        # Store a nice ID

        self.id = uuid.uuid4()  #: str: Unique capture ID

        self.stream.write(s)

    def _stream_to_file(self):

        with self.lock:

            logging.info(f"Writing to disk {self.file}")

            with FileObjectThread(open(self.file, "wb"), 'wb')  as outfile:

                outfile.write(self.stream.getbuffer())

        self.save_metadata()

    def save_metadata(self) -> None:

        gevent.get_hub().threadpool.spawn(self.synchronous_save_metadata)

        gevent.spawn(self.synchronous_save_metadata)

    def synchronous_save_metadata(self) -> None:

        """

        global EXIF_FORMATS

        if self.format.upper() in EXIF_FORMATS and self.exists:

            self.file_ready.wait()

            with self.lock:

                logging.debug("Writing exif data to capture file")

                # Extract current Exif data

                exif_dict = piexif.load(self.file)