@classmethod<EOL><INDENT>def parse(cls, fptr, offset, length):<DEDENT>
num_bytes = offset + length - fptr.tell()<EOL>read_buffer = fptr.read(num_bytes)<EOL>num_components, = struct.unpack_from('<STR_LIT>', read_buffer)<EOL>data = struct.unpack_from('<STR_LIT:>>' + '<STR_LIT>' * num_components, read_buffer,<EOL>offset=<NUM_LIT:2>)<EOL>index = data[<NUM_LIT:0>:num_components * <NUM_LIT:6>:<NUM_LIT:3>]<EOL>channel_type = data[<NUM_LIT:1>:num_components * <NUM_LIT:6>:<NUM_LIT:3>]<EOL>association = data[<NUM_LIT:2>:num_components * <NUM_LIT:6>:<NUM_LIT:3>]<EOL>return cls(index=tuple(index),<EOL>channel_type=tuple(channel_type),<EOL>association=tuple(association),<EOL>length=length, offset=offset)<EOL>
Parse component definition box.

        Parameters
        ----------
        fptr : file
            Open file object.
        offset : int
            Start position of box in bytes.
        length : int
            Length of the box in bytes.

        Returns
        -------
        ComponentDefinitionBox
            Instance of the current component definition box.