Patent ID: 6366614
Filing Date: 2002-04-02
Classification: H04N

Abstract:
In an image compression system, a sub-system for adaptively controlling the encoded bit rate of a video signal, comprising:encoder means for receiving a segment of the video signal and generating a plurality of encoded streams of data bits in accordance with a predetermined set of quantization settings chosen based on a model of quantization index versus rate; and rate controller means for receiving said plurality of encoded streams and generating a selected encoded stream in accordance with a predetermined selection algorithm, said rate controller means further comprising: selector means for receiving said plurality of encoded streams and said corresponding bit rates, and for generating said selected encoded stream in accordance with said predetermined selection criterion, said predetermined selection criterion being based on said bit rates; buffer means for receiving said selected encoded stream in preparation for transmission, said buffer having a buffer status as a result of having received said selected encoded stream; and update means for generating an updated set of said quantization settings in accordance with said buffer status, wherein said update means further receives parameters of said updated model and generates said updated set of said quantization settings in accordance with said parameters; wherein said encoder means further comprises rate measurer means for receiving said plurality of encoded streams and for determining a bit rate corresponding to each of said plurality of encoded streams, said bit rates being dependent on said quantization settings; wherein each of said quantization settings comprises: a weighting mask function generated in accordance with a quantization index; and a model element for receiving said quantization indices and said bit rates, and for deriving said updated model of quantization index versus rate in accordance with said quantization indices and said bit rates.