def __update_tfhd(self, fileobj, atom, delta, offset):
     if atom.offset > offset:
         atom.offset += delta
     fileobj.seek(atom.offset + 9)
     data = fileobj.read(atom.length - 9)
     flags = cdata.uint_be(b"\x00" + data[:3])
     if flags & 1:
         o = cdata.ulonglong_be(data[7:15])
         if o > offset:
             o += delta
         fileobj.seek(atom.offset + 16)
         fileobj.write(cdata.to_ulonglong_be(o))

 def __update_parents(self, fileobj, path, delta):
     """Update all parent atoms with the new size."""
     for atom in path:
         fileobj.seek(atom.offset)
         size = cdata.uint_be(fileobj.read(4))
         if size == 1: # 64bit
             # skip name (4B) and read size (8B)
             size = cdata.ulonglong_be(fileobj.read(12)[4:])
             fileobj.seek(atom.offset + 8)
             fileobj.write(cdata.to_ulonglong_be(size + delta))
         else: # 32bit
             fileobj.seek(atom.offset)
             fileobj.write(cdata.to_uint_be(size + delta))