Adaptive intra-frame assignment and bit-rate estimation for variable GOP length in H.264

Abstract

Video sequences usually, have many scene changes and contain rapid motion. The coding efficiency of such sequences is generally low, and the image quality fluctuates. If the rapid motion and scene changes are taken into consideration for video compression, the compression performance can be improved and the fluctuation of image quality can be reduced. An adaptive group of picture (GOP)-length structure is proposed here to consider the scene changes and rapid motion in video sequences. Our proposed algorithm for this adaptive GOP-length structure is composed of three steps. First, a correlation measure is proposed to estimate the scene changes. Second, a new intra-frame assignment method is proposed. Third, an intra-quantization parameter rule for avoiding buffer overflow and image quality fluctuation is also suggested. Our proposed algorithm has an initial delay of one-GOP length, which makes it difficult to apply for real-time communication, but this type of short initial delay is acceptable in a streaming service.