Video coding has been investigated for the novel application of video transmission over packet-switched networks. The underlying design goals are presented, together with a software implementation of a coding scheme based on the technique of subband coding. The coding scheme, which divides the input signal into frequency bands in all three dimensions, seems promising in that it lends itself to parallel implementation, is robust enough to handle errors due to lost packets, and yields high compression with sustained good quality. Moreover, it may be well integrated with the network to handle issues such as congestion control and error handling. A discussion of these issues is given, together with the results obtained from the simulated system.