          """ Run the job to remove faces from an alignments file that do not exist within a faces
          folder. """
          logger.info("[REMOVE FACES FROM ALIGNMENTS]")  # Tidy up cli output
  
          face_hashes = self._items.items
          if not face_hashes:
              logger.error("No matching faces found in your faces folder. This would remove all "
                           "faces from your alignments file. Process aborted.")
              return
  
          pre_face_count = self._alignments.faces_count
 
</s> remove         self._items = Faces(arguments.faces_dir)
 </s> add         kwargs = dict()
        if alignments.version < 2.1:
            # Update headers of faces generated with hash based alignments
            kwargs["alignments"] = alignments
        self._items = Faces(arguments.faces_dir, **kwargs) </s> remove         self._alignments.filter_hashes(face_hashes, filter_out=False)
 </s> add         self._alignments.filter_faces(frame_face_indices, filter_out=False) </s> remove                  "\nL|'leftover-faces': Identify faces in the faces folder that do not exist in "
                 "the alignments file.{2}{3}"
 </s> add  </s> remove class Merge():  # pylint:disable=too-few-public-methods
    """ Merge multiple alignments files into one.

    Parameters
    ----------
    alignments: :class:`tools.lib_alignments.media.AlignmentData`
        The alignments data loaded from an alignments file for this rename job
    arguments: :class:`argparse.Namespace`
        The :mod:`argparse` arguments as passed in from :mod:`tools.py`
    """
    def __init__(self, alignments, arguments):
        self._alignments = alignments
        self._check_versions()
        self._faces = self._get_faces(arguments)
        self._final_alignments = alignments[0]
        self._process_alignments = alignments[1:]
        self._hashes_to_frame = None

    def _check_versions(self):
        """ Ensure all alignments files are compatible versions. If not, exit with error. """
        versions = [al.version for al in self._alignments]
        logger.debug(versions)
        if any(vers < 2.0 for vers in versions) and any(vers >= 2.0 for vers in versions):
            logger.error("You have selected incompatible alignments files for merging. You cannot "
                         "merge alignments files for legacy extracted faces with aligments files "
                         "for full-head extracted faces.")
            logger.info("You can update legacy alignments files by using the Extract job in the "
                        "Alignments tool to re-extract the faces in full-head format.")
            sys.exit(0)

    @staticmethod
    def _get_faces(arguments):
        """ If faces argument is specified, load the faces folder otherwise return ``None``.

        Parameters
        ----------
        arguments: :class:`argparse.Namespace`
            The :mod:`argparse` arguments as passed in from :mod:`tools.py`

        Returns
        -------
        :class:`tools.alignments.media.Faces` or ``None``
            The faces object or ``None`` if not faces folder specified
        """
        if not hasattr(arguments, "faces_dir") or not arguments.faces_dir:
            return None
        return Faces(arguments.faces_dir)

    def process(self):
        """Run the alignments file merging process. """
        logger.info("[MERGE ALIGNMENTS]")  # Tidy up cli output
        if self._faces is not None:
            self._remove_faces()
        self._hashes_to_frame = self._final_alignments.hashes_to_frame
        skip_count = 0
        merge_count = 0
        total_count = sum([alignments.frames_count for alignments in self._process_alignments])

        with tqdm(desc="Merging Alignments", total=total_count) as pbar:
            for alignments in self._process_alignments:
                for _, src_alignments, _, frame in alignments.yield_faces():
                    for idx, alignment in enumerate(src_alignments):
                        if not alignment.get("hash", None):
                            logger.warning("Alignment '%s':%s has no Hash! Skipping", frame, idx)
                            skip_count += 1
                            continue
                        if self._check_exists(frame, alignment, idx):
                            skip_count += 1
                            continue
                        self._merge_alignment(frame, alignment, idx)
                        merge_count += 1
                    pbar.update(1)
        logger.info("Alignments Merged: %s", merge_count)
        logger.info("Alignments Skipped: %s", skip_count)
        if merge_count != 0:
            self._set_destination_filename()
            self._final_alignments.save()

    def _remove_faces(self):
        """ Removes faces from the alignments file if a faces folder has been provided and the
        faces do not exist within each alignments file. """
        face_hashes = list(self._faces.items.keys())
        del_faces_count = 0
        del_frames_count = 0
        if not face_hashes:
            logger.error("No face hashes. This would remove all faces from your alignments file.")
            return
        for alignments in tqdm(self._alignments, desc="Filtering out faces"):
            pre_face_count = alignments.faces_count
            pre_frames_count = alignments.frames_count
            alignments.filter_hashes(face_hashes, filter_out=False)
            # Remove frames with no faces
            frames = list(alignments.data.keys())
            for frame in frames:
                if not alignments.frame_has_faces(frame):
                    del alignments.data[frame]
            post_face_count = alignments.faces_count
            post_frames_count = alignments.frames_count
            removed_faces = pre_face_count - post_face_count
            removed_frames = pre_frames_count - post_frames_count
            del_faces_count += removed_faces
            del_frames_count += removed_frames
            logger.verbose("Removed %s faces and %s frames from %s",
                           removed_faces, removed_frames, os.path.basename(alignments.file))
        logger.info("Total removed - faces: %s, frames: %s", del_faces_count, del_frames_count)

    def _check_exists(self, frame, alignment, index):
        """ Remove duplicate faces from the alignments file when an instance of the face already
        exists.

        Parameters
        ----------
        frame: str
            The frame name for the current frame being processed
        alignment: dict
            The alignment dictionary for the current face in the frame
        index: int
            The face index for the current face in the frame

        Returns
        -------
        bool
            ``True`` if the face has been already been seen, otherwise ``False``
        """
        existing_frame = self._hashes_to_frame.get(alignment["hash"], None)
        if not existing_frame:
            return False
        if frame in existing_frame.keys():
            logger.verbose("Face '%s': %s already exists in destination at position %s. "
                           "Skipping", frame, index, existing_frame[frame])
        elif frame not in existing_frame.keys():
            logger.verbose("Face '%s': %s exists in destination as: %s. "
                           "Skipping", frame, index, existing_frame)
        return True

    def _merge_alignment(self, frame, alignment, idx):
        """ Merge the source alignment into the destination final alignments dictionary

        Parameters
        ----------
        frame: str
            The frame name for the current frame being processed
        alignment: dict
            The alignment dictionary for the current face in the frame
        index: int
            The face index for the current face in the frame
        """
        logger.debug("Merging alignment: (frame: %s, src_idx: %s, hash: %s)",
                     frame, idx, alignment["hash"])
        self._hashes_to_frame.setdefault(alignment["hash"], dict())[frame] = idx
        self._final_alignments.data.setdefault(frame,
                                               dict()).setdefault("faces", []).append(alignment)

    def _set_destination_filename(self):
        """ Set the destination filename """
        folder = os.path.split(self._final_alignments.file)[0]
        ext = os.path.splitext(self._final_alignments.file)[1]
        now = datetime.now().strftime("%Y%m%d_%H%M%S")
        filename = os.path.join(folder, "alignments_merged_{}{}".format(now, ext))
        logger.debug("Output set to: '%s'", filename)
        self._final_alignments.set_filename(filename)


 </s> add  </s> remove     def _build_rename_list(self):
        """ Build a list of source and destination filenames for renaming.

        Validates that all files in the faces folder have a corresponding match in the alignments
        file. Orders the rename list by destination filename to avoid potential for filename clash.

        Returns
        -------
        list
            List of tuples of (`source filename`, `destination filename`) ordered by destination
            filename
        """
        source_filenames = []
        dest_filenames = []
        errors = []
        pbar = tqdm(desc="Building Rename Lists", total=self._faces.count)
        for disk_hash, disk_faces in self._faces.items.items():
            align_faces = self._alignments.hashes_to_frame.get(disk_hash, None)
            face_error = self._validate_hash_match(disk_faces, align_faces)
            if face_error is not None:
                errors.extend(face_error)
                pbar.update(len(disk_faces))
                continue
            src_faces, dst_faces = self._get_filename_mapping(disk_faces, align_faces)
            source_filenames.extend(src_faces)
            dest_filenames.extend(dst_faces)
            pbar.update(len(src_faces))
        pbar.close()
        if errors:
            logger.error("There are faces in the given folder that do not correspond to entries "
                         "in the alignments file. Please check your data, and if neccesarry run "
                         "the `remove-faces` job. To get a list of faces missing alignments "
                         "entries, run with VERBOSE logging")
            logger.verbose("Files in faces folder not in alignments file: %s", errors)
            sys.exit(1)
        return self._sort_mappings(source_filenames, dest_filenames)

    @staticmethod
    def _validate_hash_match(disk_faces, align_faces):
        """ Validate that the hash has returned corresponding faces from disk and alignments file.

        Parameters
        ----------
        disk_faces: list
            List of tuples of (`file name`, `file extension`) for all faces that exist for the
            current hash
        align_faces: dict
            `frame filename`: `index` for all faces that exist in the alignments file for the
            current hash

        Returns
        -------
        list
            List of disk_faces that do not correspond to a matching entry in the alignments file.
            Returns `None` if there is a valid match
        """
        if align_faces is None:
            logger.debug("No matching hash found for faces: %s", disk_faces)
            return [face[0] + face[1] for face in disk_faces]
        if len(disk_faces) != len(align_faces):
            logger.debug("Number of faces mismatch for hash: (disk_faces: %s, align_faces: %s)",
                         disk_faces, align_faces)
            return [face[0] + face[1] for face in disk_faces[: len(align_faces)]]
        return None

    @staticmethod
    def _get_filename_mapping(disk_faces, align_faces):
        """ Map the source filenames for this hash to the destination filenames.

        Parameters
        ----------
        disk_faces: list
            List of tuples of (`file name`, `file extension`) for all faces that exist for the
            current hash
        align_faces: dict
            `frame filename`: `index` for all faces that exist in the alignments file for the
            current hash

        Returns
        -------
        source_filenames: list
            List of source filenames to be renamed for this hash
        dest_filenames: list
            List of destination filenames that faces for this hash are to be renamed to
            List of disk_faces that do not correspond to a matching entry in the alignments file.
            Returns `None` if there is a valid match
        """
        source_filenames = []
        dest_filenames = []
        # Force deterministic order on alignments dict for multi hash faces
        sorted_aligned = sorted(list(align_faces.items()))
        for disk_face, align_face in zip(disk_faces, sorted_aligned):
            extension = disk_face[1]
            src_fname = disk_face[0] + extension

            dst_frame = os.path.splitext(align_face[0])[0]
            dst_fname = "{}_{}{}".format(dst_frame, align_face[1], extension)
            logger.debug("Mapping rename from '%s' to '%s'", src_fname, dst_fname)
            source_filenames.append(src_fname)
            dest_filenames.append(dst_fname)
        return source_filenames, dest_filenames

    @staticmethod
    def _sort_mappings(sources, destinations):
        """ Sort the mapping lists by destinations to avoid filename clash.

        Parameters
        ----------
        sources: list
            List of source filenames in the same order as :attr:`destinations`
        destinations: dict
            List of destination filenames in the same order as :attr:`sources`

        Returns
        -------
        list
            List of tuples of (`source filename`, `destination filename`) ordered by destination
            filename
        """
        sorted_indices = [idx for idx, _ in sorted(enumerate(destinations), key=lambda x: x[1])]
        mappings = [(sources[idx], destinations[idx]) for idx in sorted_indices]
        logger.trace("filename mappings: %s", mappings)
        return mappings

 </s> add 
        frame_face_indices = self._items.items
        if not frame_face_indices:
          """ Run the job to remove faces from an alignments file that do not exist within a faces
          folder. """
          logger.info("[REMOVE FACES FROM ALIGNMENTS]")  # Tidy up cli output
  
        frame_face_indices = self._items.items
        if not frame_face_indices:
        frame_face_indices = self._items.items
        if not frame_face_indices:
              logger.error("No matching faces found in your faces folder. This would remove all "
                           "faces from your alignments file. Process aborted.")
              return
  
          pre_face_count = self._alignments.faces_count
keep keep keep keep replace replace keep keep keep keep keep
 Update extracted faces to use PNG EXIF data (#1123)

Documentation
  - Update Usage.md, align.rst and image.rst
lib.image.py
  - read_image - Remove hash return, add metadata return
  - Remove read_image_hash functions
  - Add read_image_meta functios
  - Replace encode_image_with_hash with encode_image (to store metadata)
  - Add png meta reading and writing functions
  - Update Image Loaders/Savers to handle metadata rather than hashes
lib.training_data
  - Naming updates to remove references to hashes
lib.align.Alignments
  - Add versioning notes
  - Increment alignments version to 2.1
  - Deprecate hashing lookup functions
  - Replace filter_hashes with filter_faces
lib.align.detected_face
  - DetectedFace
    - Remove hash property
    - Add png header data serializing/deserializing functions
  - Mask
    - Add png header data serializing/deserializing functions
  - add update_legacy_png_header function to update png meta data
lib.cli.args - Deprecate alignments files for training
- plugins.train.trainer
  - Update alignments/mask code to read png header data
- scripts.convert
  - Aligned images folder - read data from png headers
- scripts.extract
  - Write png header information and no longer store hash of face
- tools.alignments
  - remove leftover-faces, merge and update-hashes jobs
  - Update jobs to use png meta data rather than hashes
- tools.manual
  - Update extract code to output png meta data and don't store hashes
  - Perform check on launch that tool is not pointing at a faces folder
tools.mask
  - Update to use png meta data
tools.sort
  - Update to use png meta data 
tools/alignments/jobs.py