def get_normalized_string_from_dict(d):
    """ Normalized string representation with sorted keys.

    >>> get_normalized_string_from_dict({"max_buffer_sec": 5.0, "bitrate_kbps": 45, })
    'bitrate_kbps_45_max_buffer_sec_5.0'
    """
    return '_'.join(map(lambda k: '{k}_{v}'.format(k=k,v=d[k]), sorted(d.keys())))