'Return the blobs to be used for the next minibatch.
If cfg.TRAIN.USE_PREFETCH is True, then blobs will be computed in a
separate process and made available through self._blob_queue.'

def _get_next_minibatch(self):

    if cfg.TRAIN.USE_PREFETCH:
        return self._blob_queue.get()
    else:
        db_inds = self._get_next_minibatch_inds()
        minibatch_db = [self._roidb[i] for i in db_inds]
        return get_minibatch(minibatch_db, self._num_classes)
