Comments on "Optimal Erasure Protection for Scalably Compressed Video Streams With Limited Retransmission

In order to prove a key result for their development (Lemma 2), Taubman and Thie need the assumption that the upper boundary of the convex hull of the channel coding probability-redundancy characteristic is sufficiently dense. Since a floor value for the density level for which the claim to hold is not specified, it is not clear whether their lemma applies to practical situations. In this correspondence, we show that the constraint of sufficient density can be removed, and, thus, we validate the conclusion of the lemma for any scenario encountered in practice.