QUALITY-OPTIMIZED MPEG2 VIDEO DATA RATE CONTROL USING FUZZY-LOGIC TECHNIQUES

Fuzzy logic control has been employed to improve the rate control mech anism for a MPEG2 video encoder. The data rate of compressed video is controlled by video encoders for either variable bit rate (VBR) or con stant bit rate (CBR) applications. In VER video transmission, it is co nsidered to be more efficient to regulate the video rate by the video coder than by network management in order to avoid network congestion and maintain stable video quality. This rationale can also be applied to CBR transmission. Two fuzzy-logic-based rate control techniques are proposed which maintain the buffer occupancy within a specified range . In the proposed technique for VER applications, a video quality meas ure is taken as the crucial control parameter. In CBR rate control, th e video data rate or the buffer occupancy is also considered as a fuzz y logic variable. The proposed techniques are designed to control eith er data rate or video quality, depending on the mode of transmission, i.e. CBR or VER for the MPEG2 encoder. The performance is compared to a typical VER MPEG video coder with fixed quantiser step sizes for VER and also to the CBR video coder with MPEG2 TM5 at typical channel rat es. Simulation results are presented with peak signal-to-noise ratio, data rate variation and buffer occupancy as the performance measures.