H.264-based stream morphing with scalable motion coding

Stream morphing is a technique that allows for two or more video bitstreams coded from the same original material with different quality settings to be simulcast in an efficient way. This paper describes our second generation stream morphing system that is based on the H.264 standard rather than MPEG-4 as used in our original implementation. While the basic operation of stream morphing remains largely unchanged for H.264, a number of enhancements have been made. Firstly, enhancement layers are coded using the same low-complexity, adaptive arithmetic coder utilized by H.264 itself. Furthermore, a scalable motion model has been added which allows for the use of very low bit rates in the base layer compared to the previous approach that used the same motion vectors and macroblock partitioning modes in all layers.