1. A method for video coding, the method comprising: processing a Supplemental Enhancement Information (SEI) Network Abstraction Layer (NAL) unit, comprising a raw byte sequence payload (RBSP) that comprises one or more SEI message structures, wherein the one or more SEI message structures comprise at least one nesting SEI message structure having one or more SEI messages; and coding a syntax element indicative of a number of SEI messages comprised within the at least one nesting SEI message structure.