A method comprising: - encoding a scalable nesting supplemental enhancement information message; - associating the scalable nesting SEI message with a bitstream comprising at least two layers and with a first intra random access point (IRAP) picture within the bitstream; - including a buffering period SEI message in the scalable nesting SEI message; - indicating, in the scalable nesting SEI message, that the buffering period SEI message applies to more than one layer of the associated bitstream; - indicating, in a bitstream a start of a layer-wise start-up process by a predefined variable for one or more of the following: ∘ when a current picture is an IRAP picture that is the first picture in the bitstream; ∘ when a current picture is a broken link access picture that is the first picture in a coded video sequence; ∘ when a current picture is an instantaneous decoding refresh picture that is the first picture in a coded video sequence; - indicating in the buffering period SEI message, buffering parameters for the following types of bitstreams: a bitstream where cross-layer random access skipped (CL-RAS) pictures of IRAP pictures are present, and bitstreams where cross-layer random access skipped (CL-RAS) pictures of IRAP pictures are not present, where CL-RAS picture in a particular layer is a picture preceding, in decoding order, the first IRAP picture in said particular layer from which the decoding of said particular layer can be initialized. - encoding a scalable nesting supplemental enhancement information message; - associating the scalable nesting SEI message with a bitstream comprising at least two layers and with a first intra random access point (IRAP) picture within the bitstream; - including a buffering period SEI message in the scalable nesting SEI message; - indicating, in the scalable nesting SEI message, that the buffering period SEI message applies to more than one layer of the associated bitstream; - indicating, in a bitstream a start of a layer-wise start-up process by a predefined variable for one or more of the following: ∘ when a current picture is an IRAP picture that is the first picture in the bitstream; ∘ when a current picture is a broken link access picture that is the first picture in a coded video sequence; ∘ when a current picture is an instantaneous decoding refresh picture that is the first picture in a coded video sequence; ∘ when a current picture is an IRAP picture that is the first picture in the bitstream; ∘ when a current picture is a broken link access picture that is the first picture in a coded video sequence; ∘ when a current picture is an instantaneous decoding refresh picture that is the first picture in a coded video sequence; - indicating in the buffering period SEI message, buffering parameters for the following types of bitstreams: a bitstream where cross-layer random access skipped (CL-RAS) pictures of IRAP pictures are present, and bitstreams where cross-layer random access skipped (CL-RAS) pictures of IRAP pictures are not present, where CL-RAS picture in a particular layer is a picture preceding, in decoding order, the first IRAP picture in said particular layer from which the decoding of said particular layer can be initialized.