Patent ID: 9179165
Filing Date: 2015-11-03
Classification: H04N

Abstract:
1. A video encoding control method performed by a microprocessor operating on executable program steps stored in memory to generate a bit rate and to control the overflow and underflow in a decoder hypothetical buffer and to encode an input video signal, the method comprising the steps of: sequentially encoding each picture in an encoding-order picture group according to a predetermined encoding parameter, the encoding-order picture group including a predetermined number of pictures and being a collection of pictures successive in an encoding order; checking if underflow has occurred in the hypothetical buffer based on bit rate information generated in encoding of each picture; when the underflow has occurred in the hypothetical buffer, changing the encoding parameter in such a manner that a generated bit rate resulting from encoding is reduced and re-encoding the encoding-order picture group that is being encoded from its first picture using the changed encoding parameter, setting the retry point indicating a position of the picture from which the re-encoding starts based on a maximum inter-picture distance that is a maximum number of pictures capable of being traced back as re-encoding target pictures at the time of re-encoding; and when encoding of the encoding-order picture group is completed, checking a residual bit rate of the hypothetical buffer, setting the retry point to a first picture in a next encoding-order picture group when the residual bit rate is equal to or greater than a predetermined residual bit rate threshold value, retaining unchanged the retry point when the residual bit rate of the hypothetical buffer is smaller than the predetermined residual bit rate threshold value, and setting the retry point to the first picture in the encoding-order picture group after encoding of the first picture of the next encoding-order picture group is completed without occurrence of the underflow of the hypothetical buffer, wherein: the step of sequentially encoding includes sequentially encoding each picture in the encoding-order picture group according to an encoding parameter set according to a retry count indicating the number of times of re-encoding, the step of re-encoding includes incrementing the retry count when the underflow has occurred in the hypothetical buffer and changing the encoding parameter into an encoding parameter with which the generated bit rate resulting from encoding is reduced as a value of the retry count increases.