Fuzzy-based rate control for real-time MPEG video

| In this paper, we propose a fuzzy logic based control scheme for real time MPEG video to avoid long delay or excessive loss at the user-network interface (UNI) in an ATM network. The system consists of a shaper whose role is to smooth the MPEG output traac to reduce the burstiness of the video stream. The input and output rates of the shaper buuer are controlled by two fuzzy logic based controllers. To avoid a long delay at the shaper, the rst controller aims to tune the output rate of the shaper based on the number of available transmission credits at the UNI and the occupancy of the shaper's buuer in the video frame timescale. Based on the average occupancy of the shaper's buuer and its variance, the second controller tunes the input rate to the shaper over a much larger timescale by applying a closed loop MPEG encoding scheme. With this approach, the traac enters the network at an almost constant bit rate (with a very small variation) allowing simple network management functions such as admission control and bandwidth allocation, while guaranteeing a relatively constant video quality since the encoding rate is changed only in critical periods when the shaper buuer \threaten-s" to overrow. The performance of the proposed scheme is evaluated through numerical tests on real video sequences.