A method of decoding video data, the method comprising: decoding , from a bitstream, a plurality of syntax elements representative of which of a plurality of video coding scalabilities are enabled for the bitstream, wherein the plurality of video coding scalabilities comprise one or more of: spatial scalability, temporal scalability, SNR scalability, quality scalability, and color-bit-depth scalability, and wherein the syntax elements indicate that at least one of the plurality of video coding scalabilities is not enabled for the bitstream; determining , based on further syntax elements decoded from the bitstream, for each of the enabled video coding scalabilities, a respective number of bits to decode one or more values for one or more syntax elements representative of the respective enabled video coding scalability; and decoding , from a NAL unit header of a NAL unit of the bitstream, values for syntax elements representative of the video coding scalabilities that are enabled for the bitstream based on the determined respective numbers of bits, without decoding values for syntax elements representative of the at least one video coding scalabilities that are not enabled for the bitstream, wherein values for syntax elements representative of the at least one video coding scalabilities that are not enabled for the bitstream are not present in the NAL unit header, the NAL unit header having a size in bits that varies according to which particular video coding scalabilities are enabled for the bitstream and the numbers of bits indicated by the further syntax elements for each of the enabled video coding scalabilities. decoding , from a bitstream, a plurality of syntax elements representative of which of a plurality of video coding scalabilities are enabled for the bitstream, wherein the plurality of video coding scalabilities comprise one or more of: spatial scalability, temporal scalability, SNR scalability, quality scalability, and color-bit-depth scalability, and wherein the syntax elements indicate that at least one of the plurality of video coding scalabilities is not enabled for the bitstream; determining , based on further syntax elements decoded from the bitstream, for each of the enabled video coding scalabilities, a respective number of bits to decode one or more values for one or more syntax elements representative of the respective enabled video coding scalability; and decoding , from a NAL unit header of a NAL unit of the bitstream, values for syntax elements representative of the video coding scalabilities that are enabled for the bitstream based on the determined respective numbers of bits, without decoding values for syntax elements representative of the at least one video coding scalabilities that are not enabled for the bitstream, wherein values for syntax elements representative of the at least one video coding scalabilities that are not enabled for the bitstream are not present in the NAL unit header, the NAL unit header having a size in bits that varies according to which particular video coding scalabilities are enabled for the bitstream and the numbers of bits indicated by the further syntax elements for each of the enabled video coding scalabilities. <EOS>