An Interframe Coding Scheme for Packet Video

Interframe coding schemes though sensitive to the propagative affects of channel-errors, are much more efficient than intraframe coding schemes, when using similar data-compression techniques. Moreover, since in interframe coding, the instantaneous data-rate may vary drastically, it can benefit from the bits-on-demand property of packet-networks. We propose a layered coding-structure that contains a self-contained basic inter-frame codec as the core, and supplementary additive extended-codecs. The inter-frame codec uses a slightly modified version of motion-compensated DCT coding scheme proposed by the CCITT in reference model 8 for pX64kbit/ s videophone. It encodes the lower spatial resolution image sequence, with an adequate temporal resolution. The encoded-data it produces is assigned the highest priority. The extended-codecs allow enhancement of temporal and spatial resolutions, at the cost of increase in the data-rate. They encode the interpolative differences between the upsampled local decoded output of the basic-codec and the higher resolution input. The encoded-data of the extended codecs is assigned lower priority.