VBR MPEG video coding with dynamic bandwidth renegotiation

A scheme for VBR video coding is proposed where encoding bandwidth can be renegotiated between the encoder and the network during the duration of a call. Renegotiation can be initiated by either the encoder or the network. The encoder's bandwidth requirement is characterized by a usage parameter control (UPC) set consisting of peak rate, burst length and sustained rate. An adaptive encoder rate-control algorithm at the network interface card (NIC) computes the necessary UPC parameters to maintain the user specified quality-of-service (QoS). The network may, optionally, set a lower UPC value to deal with congestion. Simulation results are given for a rate-controlled VBR video encoder operating through an ATM network interface which supports dynamic UPC. These results suggest that dynamic band-width renegotiation could provide significant quality gains and/or bandwidth savings with graceful degradation during renegotiation transients, even in the presence of relatively large feedback delay.