Patent ID: 7496142

Claim:
A method for use in a moving pictures encoder for encoding a sequence of segments each having a plurality of pictures, each picture including a plurality of macroblocks, the method comprising the steps of: a) defining an overall target bit rate for encoding the sequence of segments; b) determining a bit allocation and target quantization step size for encoding a first segment of the sequence of segments based on a segment target bit rate calculated using said overall target bit rate; c) encoding said first segment using a variable bit rate encoding method according to the target quantization step size; d) determining a difference between the number of bits used to encode said first segment and said first segment bit allocation; e) distributing said difference for use in encoding at least one subsequent segment to determine a subsequent segment bit allocation; f) determining a new target quantization step size for encoding said subsequent segment on the basis of a new target segment bit rate calculated using said segment target bit rate and the distributed difference; and g) encoding said subsequent segment using a variable bit rate encoding method according to the new target quantization step size, wherein variable bit rate encoding is employed for encoding pictures within a segment whilst maintaining a substantially constant bit rate over said sequence.