With the rapid development of information technology

compress coding has become a heated topic in the field of multimedia storage and transmission. Aiming at the coding efficiency of video compression

ITU T and ISO/IEC jointly developed a new video coding standard named H.264/AVC in 2003. In order to transmit video efficiently on certain bandwidth

the rate fluctuation should be controlled to make it as close to the target bandwidth as possible. Although rate control is not a part of the standard

it has been playing an important role in the standard all the time. For this purpose

on the basis of JVT G012 algorithm

a new rate control algorithm based on Spatial Temporal Gradient Scale (STGS) image is presented for H.264/AVC coding to select the size of basic unit adaptively. The rate fluctuation resulted from the proposed algorithm is always close to the best case of JVT G012 algorithm. Moreover

for the low computational complexity

the proposed algorithm is easy to implement in real time applications.