Motion vector size-compensation based method for very low bit-rate video coding

In this paper, a new method to achieve better compression efficiency in low bit-rate video coding is proposed. It is based on a global bit-rate reduct ion at a macroblock level, optimizing the number of bits to code each macro block as a whole by means of motion vector and headers size compensation. T he selection of the best motion vector and different coding modes for each block of the current picture will be made depending not only on trying to c hoose the best prediction for the block, but also on the number of bits to code the associate headers, introducing some kind of penalization in the co st function. This method improves efficiency on video compression for all q ualities, but especially for low-quality video coding, whose efficiency imp rovement can reach 17%, Its implementation is simple, and compatible with m ost video-compression standards (H.263, MPEG, etc.). Results of the algorit hm in a state-of-the-art H.263+ codec are presented, and demonstrate that t he efficiency enhancement is achieved with minimal time-processing increase , and even decrease, in some conditions.