Patent ID: 7349474

Claim:
A method for controlling a bit-rate of a bitstream of encoded video signals at a variable bit-rate, the bitstream being generated by compressing a video sequence of moving pictures, wherein each picture has a plurality of macroblocks of pixels compressed by any of transform coding, temporal prediction, bi-dimensional motion-compensated interpolation or combinations thereof to produce any of I and/or P and/or B frames, the method involving quantization of said macroblocks as a function of a quantization parameter, the method comprising: defining a target bit-rate as well as maximum positive and negative error values between said target bit-rate and an average value of a current bit-rate of said bitstream; controlling said current bit-rate in order to constrain it between said maximum positive and negative error values; and defining at least one reference parameter representative of an average value of said quantization parameter over each picture and updating said at least one reference parameter within an allowed range of variation, wherein said allowed range is determined as a function of said target bit-rate and said maximum positive and negative error values, wherein said allowed range is determined as a function of at least one of: a first set of thresholds determined as a function of said target bit-rate; a second set of thresholds defined as a function of said maximum positive and negative error values; and a third set of thresholds determined experimentally.