A method, comprising: receiving at least part of a bitstream, the at least part of the bitstream comprising an encoded picture and one or more leading pictures associated with the encoded picture, the encoded picture being capable of being used as a random access point, RAP, picture, wherein the one or more associated leading pictures are decodable or non-decodable leading pictures, wherein a network abstraction layer, NAL, unit type associated with each of the one or more associated leading pictures identifies the associated leading picture as: a picture that is to be decoded when decoding starts at the encoded picture in bitstream order, or a picture that is not to be decoded when decoding starts at the encoded picture in bitstream order; beginning decoding at the encoded picture as a random access point, including decoding the encoded picture; and decoding the one or more leading pictures associated with the encoded picture, comprising: decoding the leading picture if the NAL, unit type of the leading picture identifies the associated leading picture as a picture that is to be decoded when decoding starts at the encoded picture in bitstream order, and skipping the decoding of the leading picture if the NAL, unit type of the leading picture identifies the the associated leading picture as a picture that is not to be decoded when decoding starts at the encoded picture in bitstream order, wherein a leading picture is a picture that follows the encoded picture in bitstream order but precedes the encoded picture in display order and wherein whether or not a leading picture can be decoded is based on whether a decoding of the leading picture depends on some pictures that appear prior to the encoded picture in bitstream order. receiving at least part of a bitstream, the at least part of the bitstream comprising an encoded picture and one or more leading pictures associated with the encoded picture, the encoded picture being capable of being used as a random access point, RAP, picture, wherein the one or more associated leading pictures are decodable or non-decodable leading pictures, wherein a network abstraction layer, NAL, unit type associated with each of the one or more associated leading pictures identifies the associated leading picture as: a picture that is to be decoded when decoding starts at the encoded picture in bitstream order, or a picture that is not to be decoded when decoding starts at the encoded picture in bitstream order; a picture that is to be decoded when decoding starts at the encoded picture in bitstream order, or a picture that is not to be decoded when decoding starts at the encoded picture in bitstream order; beginning decoding at the encoded picture as a random access point, including decoding the encoded picture; and decoding the one or more leading pictures associated with the encoded picture, comprising: decoding the leading picture if the NAL, unit type of the leading picture identifies the associated leading picture as a picture that is to be decoded when decoding starts at the encoded picture in bitstream order, and skipping the decoding of the leading picture if the NAL, unit type of the leading picture identifies the the associated leading picture as a picture that is not to be decoded when decoding starts at the encoded picture in bitstream order, decoding the leading picture if the NAL, unit type of the leading picture identifies the associated leading picture as a picture that is to be decoded when decoding starts at the encoded picture in bitstream order, and skipping the decoding of the leading picture if the NAL, unit type of the leading picture identifies the the associated leading picture as a picture that is not to be decoded when decoding starts at the encoded picture in bitstream order, wherein a leading picture is a picture that follows the encoded picture in bitstream order but precedes the encoded picture in display order and wherein whether or not a leading picture can be decoded is based on whether a decoding of the leading picture depends on some pictures that appear prior to the encoded picture in bitstream order.