In this paper, we investigate the issues over the smooth quality and the smooth bit rate during rate control (RC) in H.264/AVC. An adaptive quantization-parameter (Q p clip scheme is proposed to optimize the quality smoothness while keeping the bit-rate fluctuation at an acceptable level. First, the frame complexity variation is studied by defining a complexity ratio between two nearby frames. Second, the range of the generated bits is analyzed to prevent the encoder buffer from overflow and underflow. Third, based on the safe range of the generated bits, an optimal Q p clip range is developed to reduce the quality fluctuation. Experimental results demonstrate that the proposed Q p clip scheme can achieve excellent performance in quality smoothness and buffer regulation. © 2011 IEEE.
Bibliographical noteThis work was supported in part by the Hong Kong Research Grants Council General Research Fund under Project 9041495 (CityU 115109), by the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, by the Program for New Century Excellent Talents in University of China under Grant NCET-10-0634, by the Shanghai Pujiang Program under Grant 11PJ1409400, by the National Natural Science Foundation of China under Grant 61102059, and by the National Basic Research Program (973 Program) of China under Grant 2010CB328101.
- Encoder buffer
- quantization-parameter clip
- rate control (RC)
- smooth quality