'Read a single buffer with raw data.
Parameters
nchan : int
The number of channels (info[\'nchan\']).
Returns
raw_buffer : float array, shape=(nchan, n_times)
The raw data.'

def read_raw_buffer(self, nchan):

    (tag, this_buff) = _recv_tag_raw(self._data_sock)
    while (tag.kind != FIFF.FIFF_DATA_BUFFER):
        (tag, this_buff) = _recv_tag_raw(self._data_sock)
    buff = StringIO(this_buff)
    tag = read_tag(buff)
    raw_buffer = tag.data.reshape((-1), nchan).T
    return raw_buffer
