The network abstraction layer (NAL) defines the encapsulation of the coded video data for transportation and
storage. The encoded information is organized in NAL units, which contain either data of the video coding layer (VCL) or non-VCL data.
A NAL unit consists of a two-byte NAL unit header and the raw byte sequence payload (RBSP). The NAL unit header includes the syntax element for the NAL unit type (NUT), which indicates the content of the NAL unit. The last byte of the RBSP containing coded data includes the RBSP stop bit (‘1’) followed by ‘0’ bits such that byte alignment is achieved. The concatenation of the bits of the RBSP bytes before the RBSP stop bit constitutes the string of data bits (SODB). The SODB contains all coded data that is needed for the decoding process. Within the SODB, the bits of the bytes are concatenated from the most to the least significant bit.