def add_rnn_encoder_arguments(group):
    """Define arguments for RNN encoder."""
    group.add_argument(
        "--elayers",
        default=4,
        type=int,
        help="Number of encoder layers (for shared recognition part "
        "in multi-speaker asr mode)",
    )
    group.add_argument(
        "--eunits",
        "-u",
        default=300,
        type=int,
        help="Number of encoder hidden units",
    )
    group.add_argument(
        "--eprojs", default=320, type=int, help="Number of encoder projection units"
    )
    group.add_argument(
        "--subsample",
        default="1",
        type=str,
        help="Subsample input frames x_y_z means subsample every x frame "
        "at 1st layer, every y frame at 2nd layer etc.",
    )

    return group