Joint rate control for VBR MPEG video on PVC ATM links

Abstract

A joint rate control algorithm for variable bit rate(VBR) MPEG-compressed digital video on point-to-point permanent virtual circuit (PVC) ATM links is proposed.The algorithm controls the encoding mode of a numberof video encoders that operate either on VBR or constantbit rate (CBR) mode. The algorithm selects the encodingmode based on the buffer occupancy of a multiplexer co-located with the encoders that interfaces them to the PVClink. VBR encoding is the predominant encoding mode usedduring congestion-free periods. CBR mode is used only during congested periods. When CBR is selected, new bit ratesare jointly assigned to the encoders based on their relativeencoding complexities. The bit rate assigned to the encodersare enforced by a CBR rate control local to each encoder.The performance of the joint rate control algorithm is evaluated through simulation of a packet multiplexer, where anumber of connections are multiplexed onto a fixed-capacity channel. The performance is compared to that of multiplexing conventional CBR and open-loop VBR from the videoquality and bandwidth efficiency points of view. Simulation results show that the proposed algorithm improves performance over multiplexed conventional CBR or open-loop VBR MPEG video, without significantly increasing implementation complexity. The application of the algorithm, tovideo-on-demand over ATM is discussed.