A robust and adaptive rate control algorithm for object-based video coding

This paper proposes a rate control algorithm for single and multiple objects video coding. The algorithm exploits prediction and feedback control to achieve accurate bit rate while maximizing the picture quality and simultaneously effectively handling buffer fullness. The algorithm estimates the bit budget of a frame based on its global coding complexity, and dynamically distributes the target bits for each object within a frame according to the object's coding complexity. Exploiting a novel buffer controller based on the proportional-integral-derivative (PID) technique used in automatic control systems, the algorithm effectively reduces the deviation between the current buffer fullness and the target buffer fullness, and minimizes the buffer overflow or underflow. The algorithm dynamically adjusts several parameters to further improve the system performance. A scene-change handling method is used to deal with scene changes. The combination of prediction and feedback control improves the adaptability of the rate controller under complicated environments; it also decreases the effect of random disturbance and the deviation caused by the variance between the real system and its statistical model. Overall, the proposed algorithm successfully achieves accurate target bit rate, provides promising coding quality, decreases buffer overflow/underflow and lowers the impact of a scene change.