This paper introduces a new concept called lossless aggregation for the transmission of video information. It is a scheme for the delivery of variable bit-rate (VBR) video streams from a video server to a group of users over a shared channel. No data are dropped at the source during the adaptation process that reshapes the VBR video traffic to conform to the channel bit-rate characteristics. The transmission schedules of individual video streams evolve in a dynamic way that depends on their relative traffic characteristics. Receiver buffer underflow and overflow are prevented. Therefore, the data delivery process does not cause any loss of image quality. We show that very significant receiver-buffer reduction can be achieved with aggregation compared with the independent transmission of individual video streams over separate channels. Several bandwidth allocation methods for aggregation are studied extensively. The frame equalization algorithm stands out in terms of its simplicity and optimality.

Video information can be transmitted using a variable bit rate (VBR) or a constant bit rate (CBR) virtual channel in a broadband network (e.g., an ATM network). CBR transmission has many advantages from the networking standpoint: multiplexing, bandwidth allocation, user/network contractual agreement, and network-usage tariff are all simpler under the CBR transmission framework. This paper considers how to deliver video over a CBR channel. It introduces a new concept called lossless aggregation for the transmission of a bundle of stored videos over a common channel. No data is dropped during the adaptation process and hence it does not cause any image degradation. We show that significant receiver buffer reduction can be achieved using lossless aggregation.