nits - RawMbBits * PicSizeInMbs 1024) - NumBytesInVcINALunits) ) / 3). Depending on the variable k the following applies: If k is less than or equal to 0, no cabac_zero_word is appended to the NAL unit. Otherwise (k is greater than 0), the 3-byte sequence 0x000003 is appended k times to the NAL unit after encapsulation, where the first two bytes 0x0000 represent a cabac_zero_word and the third byte 0x03 represents an mulation_prevention_three_byte. Rec. ITU-T H.264 (01/2012) Annex A Profiles and levels (This annex forms an integral part of this Recommendation | International Standard.) Profiles and levels specify restrictions on bitstreams and hence limits on the capabilities needed to decode the bitstreams. Profiles and levels may also be used to indicate interoperability points between individual decoder implementations. NOTE 1 - This Recommendation | International Standard does not include individually selectable "options" at the decoder, as this would increase interoperability difficulties. Each profile specifies a subset of algorithmic features and limits that shall be supported by all decoders conforming to that profile. NOTE 2 - Encoders are not required to make use of any particular subset of features supported in a profile. Each level specifies a set of limits on the values that may be taken by the syntax elements of this Recommendation | International Standard. The same set of level definitions is used with all profiles, but individual implementations may support a different level for each supported profile. For any given profile, levels generally correspond to decoder processing load and memory capability. The profiles that are specified in clause A.2 are also referred to as the profiles specified in Annex A. Requirements on video decoder capability Capabilities of video decoders conforming to this Recommendation | International Standard are specified in terms of the ability to decode video streams conforming to the constraints of profiles and levels specified in this annex. For each such profile, the 