An apparatus, a method and a computer program for image sequence coding and decoding

A method for signaling reference pictures of a picture sequence encoded in a bitstream, the method comprising

• classifying pictures of the picture sequence into reference pictures and non- reference pictures;
• providing each reference picture with a unique picture identifier;
• determining, at least for inter-coded pictures of the picture sequence, all unique combinations of the picture identifier and at least one reference picture identifier, where the at least one reference picture identifier for a particular picture identifies all pictures that may be used as a reference for predicting said particular picture;
• assigning intra-coded reference pictures at least with their unique picture identifier and the inter-coded pictures with their corresponding unique combination of the picture identifier and the at least one reference picture identifier.

An apparatus comprising

• at least one processor and at least one memory, said at least one memory stored with code thereon, which when executed by said at least one processor, causes the apparatus to perform at least
• classifying pictures of a picture sequence into reference pictures and non-reference pictures;
• providing each reference picture with a unique picture identifier;
• determining, at least for inter-coded pictures of the picture sequence, all unique combinations of the picture identifier and at least one reference picture identifier, where the at least one reference picture identifier for a particular picture identifies all pictures that may be used as a reference for predicting said particular picture;
• assigning intra-coded reference pictures at least with their unique picture identifier and the inter-coded pictures with their corresponding unique combination of the picture identifier and the at least one reference picture identifier.

A computer readable storage medium stored with code thereon for use by an apparatus, which when executed by a processor, causes the apparatus to perform:

• classifying pictures of a picture sequence into reference pictures and non-reference pictures;
• providing each reference picture with a unique picture identifier;
• determining, at least for inter-coded pictures of the picture sequence, all unique combinations of the picture identifier and at least one reference picture identifier, where the at least one reference picture identifier for a particular picture identifies all pictures that may be used as a reference for predicting said particular picture;
• assigning intra-coded reference pictures at least with their unique picture identifier and the inter-coded pictures with their corresponding unique combination of the picture identifier and the at least one reference picture identifier.

A method comprising:

• receiving signaling comprising indications for reference pictures required for decoding a picture of a picture sequence;
• determining an indication for at least a unique picture identifier for an intra-coded reference picture and a unique combination of a picture identifier and at least one reference picture identifier for an inter-coded picture;
• and
• determining from the at least one reference picture identifier for a particular inter-coded picture all pictures referred to by said particular inter-coded picture.

An apparatus comprising

• at least one processor and at least one memory, said at least one memory stored with code thereon, which when executed by said at least one processor, causes the apparatus to perform at least
• receiving signaling comprising indications for reference pictures required for decoding a picture of a picture sequence;
• determining an indication for at least a unique picture identifier for an intra-coded reference picture and a unique combination of a picture identifier and at least one reference picture identifier for an inter-coded picture;
• and
• determining from the at least one reference picture identifier for a particular inter-coded picture all samples referred to by said particular inter-coded picture.

A computer readable storage medium stored with code thereon for use by an apparatus, which when executed by a processor, causes the apparatus to perform:

• receiving signaling comprising indications for reference pictures required for decoding a picture of a picture sequence;
• determining an indication for at least a unique picture identifier for an intra-coded reference picture and a unique combination of a picture identifier and at least one reference picture identifier for an inter-coded picture;
• and
• determining from the at least one reference picture identifier for a particular inter-coded picture all pictures referred to by said particular inter-coded picture.