Constraints on Variable Bit-Rate Video for

We consider constraints on the encoded bit rate of a video signal that are imposed by a channel and encoder and decoder buffers. We present conditions that ensure that the video encoder and decoder buffers do not overflow or underflow when the channel can transmit a variable bit rate. Using these conditions and a commonly proposed network-user contract, we examine the effect of a network policing function on the allow- able variability in the encoded video bit rate. We describe how these ideas might be implemented in a system that controls both the encoded and transmitted bit rates. Finally, we present the performance of video that has been encoded using the derived constraints for the leaky bucket channel.