A means for delivering video frames from one point to another; a sequence of frames submitted to the channel input results in a similar (not necessarily identical) sequence of frames at the channel output. Note: The visual channel may be comprised of the following components: video format conversion devices, encoders (compressors) and decoders (decompressors,) rate smoothing buffers, multiplexors and demultiplexors, modulators and demodulators, transmission facilities, switches, multi-point conference units, and other components necessary to achieve the desired channel characteristics.