US Patent 7082221 Bandwidth determination for multiple layer digital video

In an encoding process, video data are represented as a bitstream of quantized base data and enhancement data, which capture the difference between a quantized base video picture and an original unquantized input video picture. Due to bandwidth constraints on a communication channel, it may be unfeasible to transmit all enhancement data. During the encoding process, the enhancement data may be divided into “layers” based upon bandwidth restrictions. Following transmission, the layers are recombined and are added to the base data by a decoder, producing a viewable video sequence.