| 摘要 |
<p>A method for controlling the bit-rate of a bitstream (OS) of encoded video signals at a variable bitrate (VBR), the bitstream being generated by compressing a video sequence of moving pictures (IS), wherein each picture comprises a plurality of macroblocks of pixels compressed by any of transform coding (DCT), 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 effected as a function of a quantization parameter (mquant). The method includes the steps of: defining a target bit-rate (target_bitrate) as well as maximum positive (max_err_pos) and negative (max_err_neg) error values between the target bit-rate and an average value of the current bit-rate of the bitstream (OS), controlling the current bit-rate in order to constrain it between said maximum positive and negative error values, and defining an allowed range of variation for updating at least one reference parameter (Qbase) representative of the average value of the quantization parameter (mquant) over each picture, wherein said allowed range is determined as a function of the target bit-rate (target_bitrate) and the maximum positive and negative error values (max_err_pos, max_err_neg). <IMAGE></p> |
