Method and apparatus for dynamically controlling encoding parameters of

Abstract

A method and apparatus for dynamically allocating the available bandwidth of a common transmission channel of a multiplexed system among multiple encoders in such a manner as to maximize and equalize the quality of the encoded data output by all of the encoders, while also preventing underflow or overflow of encoder or decoder buffers at each end of the common transmission channel, and moreover, while also ensuring compliance with (i.e., without violating) the data encoding and transmission protocol utilized by the system. Further, the bandwidth of the common transmission channel is preferably allocated using an algorithm that does not impose any constraints on the size of the encoder or decoder buffers, other than any constraints specified by the data transmission protocol employed in transmitting the encoded data over the common transmission channel. In a presently preferred embodiment, in which video signals from multiple sources are encoded, both the output channel rate ('bit rate') of each of the encoders and the target number of bits for each picture that is encoded by each encoder are controlled by a controller in accordance with a control algorithm which ensures that the quality of the encoded pictures output by all of the encoders is equalized and maximized, that no underflow or overflow of the encoder or decoder buffers occurs, and that the data encoding and transmission protocol utilized by the system is not violated. Further, the control algorithm employed by the controller preferably does not impose any constraints on the sizes or relative sizes of the encoder or decoder buffers. Moreover, the control algorithm employed by the controller preferably maintains all of the encoder buffers as empty as possible in order to provide increased flexibility to the rate allocation procedure.