This paper presents a method that, by using a tree splay, dynamically modifies the fixed table of a VLC used in the standards and thus improves the performance of a video encoder. The previous standards, which drew up tables by using a limited number of images, were not able to accommodate the characteristics of new image input. The new method proposed in this paper employs the probabilistic characteristics of an image input, thus making encoding more effective. Furthermore, the present study also proposes a method to regulate the weight in order that the accumulated probabilities can make a dominant symbol emerge, while keeping the probability adequate and thus maximally accommodating the characteristics of the image input. The results from applying the proposed method to a variety of image sequences showed that, while various types of images yielded slightly different results, it improved the performance up to a maximum of 0.23㏈, compared to MPEG-4 standard.