in dataset/mocap.py [0:0]
    def _index_dir(self, path):
        """Recursively add paths to the set of
        indexed files
        Arguments:
            path {str} -- folder path
        Returns:
            dict -- indexed files per root dir
        """
        indexed_paths = dict()
        sub_dirs, _ = io.get_subdirs(path)
        if set(self.ROOT_DIRS) <= set(sub_dirs):
            # get files from subdirs
            n_frames = -1
            # let's extract the rgba and json data per frame
            for sub_dir in self.ROOT_DIRS:
                d_path = os.path.join(path, sub_dir)
                _, paths = io.get_files(d_path)
                if n_frames < 0:
                    n_frames = len(paths)
                else:
                    if len(paths) != n_frames:
                        self.logger.error(
                            'Frames info in {} not matching other passes'.format(d_path))
                encoded = [p.encode('utf8') for p in paths]
                indexed_paths.update({sub_dir: encoded})
            return indexed_paths
        # initialize indexed_paths
        for sub_dir in self.ROOT_DIRS:
            indexed_paths.update({sub_dir: []})
        # check subdirs of path and merge info
        for sub_dir in sub_dirs:
            indexed = self._index_dir(os.path.join(path, sub_dir))
            for r_dir in self.ROOT_DIRS:
                indexed_paths[r_dir].extend(indexed[r_dir])
        return indexed_paths