Media is partitioned into k recurring frames or packets. Recurring frames of the same position 1 to k collectively define k media substreams which may be communicated from sending computers to a receiving computer over a computer network pursuant to a substream mask. The substream mask is defined by the receiving computer. Received substreams may be communicated to subsequent computers, and/or buffered for reassembly and playback at the receiving computer. Network node lists for substream and packet mask negotiation may be communicated to the receiving computer by sending computers or a rendezvous host.