Methods, apparatuses, and computer-readable media for determining a source block size are presented. A sender transmits received media as source blocks. The sender receives a value N, a target number of packets from which a receiver can recover a source block with high fidelity; a value P′, a target packet payload size; a value O, a symbol reception overhead value; and a value R, a target upper bound on data reception overhead. The sender determines a value K, a number of symbols to be used per source block, based on the values N, P′, O and R. The source symbols of the source blocks are encoded into encoded symbols. In some cases, the encoded symbols include the source symbol, and in other cases the encoded symbols do not include the source symbols. The encoded symbols are packetized into at least N packets for transmission to the receiver.