A novel MPEG-4 rate control method with spatial resolution conversion for low bit-rate coding

MPEG-4 is very powerful encoding algorithm for a wide range of image sequences. The scalable rate control (SRC) used in MPEG-4 causes frequent frame skipping. The frequent frame skipping results in jerky degradation. In order to prevent frequent frame skipping in highly active scenes, reduced resolution VOP (RRV) is introduced in MPEG-4. In RRV, the encoding is performed with low spatial resolution when the input signal belongs to a highly active scene. However, SRC and RRV are controlled independently. Thus, RRV cannot work well for avoiding frequent frame skipping. The paper presents a novel rate control method for MPEG-4. In the proposed method, reduced resolution VOP is included in the SRC. Thus, it can avoid frequent frame skipping effectively. Consequently, the encoded stream has high temporal resolution while preserving high image quality.