Patent ID: 8774275

Claim:
A method of video coding comprising a) dividing a sequence to be encoded into a plurality of temporal portions; b) analyzing the sequence to determine for each portion, in accordance with a plurality of encoding quality settings, data establishing the relationship between the quality settings and (i) a quality metric for the portion and (ii) the number of bits generated by encoding the portion at that quality setting; c) analyzing the data along with a target quality and target bit rate to choose a set of quality settings, one per portion, that tends to minimize a combined quality cost for the sequence within the constraint that transmission of encoded video at the target bit rate via transmitting and receiving buffers of specified size and initial receiver buffer fullness shall not cause underflow nor overflow; wherein the combined quality cost is the sum of individual quality costs each of which is a function of the amount of deviation of the quality metric of the respective encoded portion from the target quality, the function being such that the cost generally increases as the absolute value of the deviation increases; and d) encoding the sequence using the chosen quality settings; wherein: the target bit rate is specified and the method further includes the step of determining the target quality that corresponds to this bit rate; the target quality is determined by iteratively performing a plurality of trial analyses in accordance with step (c) with the specified target bit rate and a plurality of target quality values chosen to progressively reduce a measure of variation of actual quality during the iteration; and the target quality is determined by (i) defining a first target quality; (ii) measuring the average quality and standard deviation of quality obtained using this target; and (iii) if the standard deviation exceeds a threshold, setting the target quality to the average quality obtained and repeating steps (i) and (ii) at least once.