US Patent 9270989 Method and apparatus for video coding

A method, apparatus and computer program product are provided that permit values of certain parameters or syntax elements, such as the HRD parameters and/or a level indicator, to be taken from a syntax structure, such as a sequence parameter set. In this regard, values of certain parameters or syntax elements, such as the HRD parameters and/or a level indicator, may be taken from a syntax structure of a certain other layer, such as the highest layer, present in an access unit, coded video sequence and/or bitstream even if the other layer, such as the highest layer, were not decoded. The syntax element values from the other layer, such as the highest layer, may be semantically valid and may be used for conformance checking, while the values of the respective syntax elements from other respective syntax structures, such as sequence parameter sets, may be active or valid otherwise.