utive in decoding order and contain exactly one primary coded picture. In addition to the primary coded picture, an access unit may also contain one or more redundant coded pictures, one auxiliary coded picture, or other NAL units not containing slices or slice data partitions of a coded picture. The decoding of an access unit always results in a decoded picture. AC transform coefficient: Any transform coefficient for which the frequency index in one or both dimensions is non-zero. adaptive binary arithmetic decoding process: An entropy decoding process that derives the values of bins from a bitstream produced by an adaptive binary arithmetic encoding process. Rec. ITU-T H.264 (01/2012) adaptive binary arithmetic encoding process: An entropy encoding process, not normatively specified in this Recommendation | International Standard, that codes a sequence of bins and produces a bitstream that can be decoded using the adaptive binary arithmetic decoding process. alpha blending: A process not specified by this Recommendation I International Standard, in which an auxiliary coded picture is used in combination with a primary coded picture and with other data not specified by this Recommendation International Standard in the display process. In an alpha blending process, the samples of an auxiliary coded picture are interpreted as indications of the degree of opacity (or, equivalently, the degrees of transparency) associated with the corresponding luma samples of the primary coded picture. arbitrary slice order (ASO): A decoding order of slices in which the macroblock address of the first macroblock of some slice of a slice group may be less than the macroblock address of the first macroblock of some other preceding slice of the same slice group or, in the case of a picture that is coded using three separate colour planes, some other preceding slice of the same slice group within the same colour plane, or in which the slices of a slice group of a picture may be interleaved with the slices of one or more other slice gro