Visual communications over wireless networks require the efficient and robust coding of video signals for transmission over wireless links having time-varying channel capacity.We compare several schemes for encoding video data into two priority streams, thereby enabling the transmission of video data over wireless links to be switched between two bit rates. An H.261 (p x 64) a1 orithm is modified to implement each candidate scheme. h e algorithms are evaluated for a microcellular wireless environment and a clearchannel bit rate of 65 kb/s. Our results show that by combining layering with automatic-repeat request (wireless-)link control, almost-wireline visual quality can be achieved.