e 7-2 shall be used to derive the picture-level scaling list for index i. Otherwise (seq_scaling_matrix_present_flag is equal to 1), the scaling list fall-back rule set B as specified in Table 7-2 shall be used to derive the picture-level scaling list for index i. Rec. ITU-T H.264 (01/2012) second_chroma_qp_index_offset specifies the offset that shall be added to QPy and QSy for addressing the table of QPc values for the Cr chroma component. The value of second_chroma_qp_index_offset shall be in the range of -12 +12, inclusive. When second_chroma_qp_index_offset is not present, it shall be inferred to be equal to chroma_qp_index_offset. NOTE - When ChromaArrayType is equal to 0, the values of bit_depth_chroma_minust chroma_qp_index_offset and second_chroma_qp_index_offset are not used in the decoding process. In particular, when separate_colour_plane_ is equal to 1, each colour plane is decoded as a distinct monochrome picture using the luma component decoding process (except for the selection of scaling matrices), including the application of the luma quantisation parameter derivation process without application of an offset for the decoding of the pictures having colour_plane_id not equal to 0. 7.4.2.3 Supplemental enhancement information RBSP semantics Supplemental Enhancement Information (SEI) contains information that is not necessary to decode the samples of coded pictures from VCL NAL units. 7.4.2.3.1 Supplemental enhancement information message semantics An SEI RBSP contains one or more SEI messages. Each SEI message consists of the variables specifying the type payloadType and size payloadSize of the SEI payload. SEI payloads are specified in Annex D. The derived SEI payload size payloadSize is specified in bytes and shall be equal to the number of RBSP bytes in the SEI payload. NOTE - The NAL unit byte sequence containing the SEI message might include one or more emulation prevention bytes (represented by emulation prevention_three_b syntax elements). Since the payload size of an SEI message is specifie