Reduced worst-case context-coded bins in video compression with parity hiding

摘要

Methods and devices for reconstructing coefficient levels from a bitstream of encoded video data for a coefficient group in a transform unit. Parity hiding is used to signal the parity of the upper left coefficient of the coefficient group. Based on the parity, either the significant coefficient flag or the greater-than-one flag is encoded/decoded for that coefficient, but not both. The greater-than-one flag is encoded/decoded irrespective of whether a maximum number of greater-than-one flags have been encoded/decoded with respect to the other coefficients in the coefficient group.

主权项

1. A method of decoding a bitstream of encoded video to reconstruct coefficients of a coefficient group in a video decoder, the coefficient group including an upper left coefficient, the method comprising:
decoding flags for reconstructing the coefficients of the coefficient group other than the upper left coefficient, wherein decoding includes, for each non-zero coefficient, decoding a greater-than-one flag if the number of previously decoded greater-than-one flags for the coefficient group is less than a predetermined threshold number; determining a parity of the upper left coefficient; decoding a significant-coefficient flag for the upper left coefficient only if the parity is even; and decoding a greater-than-one flag for the upper left coefficient only if the parity is odd and irrespective of the predetermined threshold number.