Reference picture signaling

A method of decoding an encoded representation of a picture in a video stream of multiple pictures, the method comprising:

• retrieving, from the encoded representation of the picture, buffer description information defining a plurality of reference pictures;
• determining, based on the buffer description information, a reference picture identifier that identifies a reference picture among the plurality of reference pictures that comprises a decoding reference for the picture;
• determining whether the reference picture identified by the reference picture identifier is one of missing or non-existing;
• responsive to determining the reference picture identified by the reference picture identifier is one of missing or non-existing, generating a non-existing picture with parameters set to parameters of the reference picture identified by the reference picture identifier;
• and
• updating a decoded picture buffer based on the reference picture identifier.

A decoder configured to decode an encoded representation of a picture in a video stream of multiple pictures, the decoder comprising:

• at least one processor;
• and
• a memory storing instructions which, when executed by the at least one processor causes the decoder to:
• retrieve buffer description information defining a plurality of reference pictures, wherein the buffer description information is retrieved from the encoded representation of the picture;
• determine, based on the buffer description information, a reference picture identifier that identifies a respective reference picture among the plurality of reference pictures, the respective reference picture comprising a decoding reference for the picture, wherein the decoder is configured to i) retrieve, based on the buffer description information, a respective delta identifier comprising a difference between the reference picture identifier and a picture identifier identifying the picture, and ii) calculate the reference picture identifier based on the picture identifier and the respective delta identifier;
• and
• update a decoded picture buffer based on the reference picture identifier.

A decoder configured to decode an encoded representation of a picture in a video stream of multiple pictures, the decoder comprising:

• a data retriever circuit configured to retrieve buffer description information defining a plurality of reference pictures, wherein the buffer description information is retrieved from the encoded representation of the picture;
• a picture identifier determiner circuit configured to:
• determine, based on the buffer description information, a reference picture identifier that identifies a respective reference picture among the plurality of reference pictures, the respective reference picture comprising a decoding reference for the picture;
• determine whether the reference picture identified by the reference picture identifier is one of missing or non-existing;
• responsive to determining the reference picture identified by the reference picture identifier is one of missing or non-existing, generate a non-existing picture with parameters set to parameters of the reference picture identified by the reference picture identifier;
• and
• a buffer manager circuit configured to update a decoded picture buffer based on the reference picture identifier.

A receiver comprising:

• an input section circuit configured to receive encoded representations of multiple pictures in a video stream;
• a decoder circuit configured to decode the encoded representations of the multiple pictures;
• and
• an output section circuit configured to output decoded pictures of the video stream, wherein the decoder circuit comprises:
• a data retriever circuit configured to retrieve buffer description information defining a plurality of reference pictures, wherein the buffer description information is retrieved from the encoded representation of a picture;
• a picture identifier determiner circuit configured to determine, based on the buffer description information, a reference picture identifier that identifies a respective reference picture among the plurality of reference pictures, the respective reference picture comprising a decoding reference for the picture, wherein the picture identifier determiner is configured to i) retrieve, based on the buffer description information, a respective delta identifier comprising a difference between the reference picture identifier and a picture identifier identifying the picture, and ii) calculate the reference picture identifier based on the picture identifier and the respective delta identifier;
• and
• a buffer manager circuit configured to update a decoded picture buffer based on the reference picture identifier.

A computer program product comprising a non-transitory computer-readable medium storing program instructions for decoding an encoded representation of a picture in a video stream of multiple pictures, the program instructions when executed by a processor of a node in an access network cause the node to perform operations comprising:

• retrieving, from the encoded representation of the picture, buffer description information defining a plurality of reference pictures;
• determining, based on the buffer description information, a reference picture identifier that identifies a respective reference picture among the plurality of reference pictures, the respective reference picture comprising a decoding reference for the picture, wherein determining the reference picture identifier comprises:
• (i) retrieving, based on the buffer description information, a delta identifier comprising a difference between the reference picture identifier and a picture identifier identifying the picture;
• and
• (ii) calculating the reference picture identifier based on the picture identifier and the delta identifier;
• and
• updating a decoded picture buffer based on the reference picture identifier.