NAL unit containing a buffering period SEI message is present, the following applies: If the buffering period SEI message is the only buffering period SEI message in the access unit and it is not included in a scalable nesting SEI message, the buffering period SEI message shall be the first SEI message payload of the first SEI NAL unit in the access unit. Otherwise (the buffering period SEI message is not the only buffering period SEI message in the access unit or it is included in a scalable nesting SEI message), the following constraints are specified: When a buffering period SEI message that is not included in a scalable nesting SEI message is present, this buffering period SEI message shall be the only SEI message payload of the first SEI NAL unit in the access unit. A scalable nesting SEI message that includes a buffering period SEI message shall not include any other SEI messages and the scalable nesting SEI message that includes a buffering period SEI message shall be the only SEI message inside an SEI NAL unit. All SEI NAL units that precede an SEI NAL unit that contains a scalable nesting SEI message with buffering period SEI message as payload in an access unit shall only contain buffering period SEI messages or scalable nesting SEI messages with a buffering period SEI message as payload. When present, a scalable nesting SEI message with ll_layer_representations in au flag equal to 1 and buffering period SEI message as payload shall be the first scalable nesting SEI message in an access unit. Any scalable nesting SEI message with a buffering period SEI message as payload that immediately precedes another scalable nesting SEI message with a buffering period SEI message as payload shall have values of 128 * sei_dependency_id[ i ]) + 8 * sei_quality temporal_i for all present i, that are less than any of the values of 128 * sei_dependency_id[ i_quality_i sei_temporal_i Rec. ITU-T H.264 (01/2012) in the immediately following scalable nesting SEI message with a buffering period SEI message as payload. The fo