Encoder and decoder, encoding method and decoding method for versatile spatial partitioning of coded pictures

An apparatus for encoding a picture, wherein the picture includes a plurality of coding tree units (CTUs) and a plurality of coding areas, with each coding area having one or more CTUs, the apparatus comprising:

• at least one processor configured to:
• set, for each coding area, a horizontal coding area boundary and a vertical coding area boundary, wherein:
• at least one of the horizontal coding area boundary or the vertical coding area boundary of a first coding area of the plurality of coding areas extends from a picture boundary of the picture to an opposing picture boundary of the picture;
• and
• the plurality of coding areas includes the first coding area and a second coding area, wherein the first coding area encloses the second coding area within the first coding area;
• transmit coding area indication data, wherein the coding area indication data includes at least one of:
• a coding area width that specifies a number of CTUs that are arranged in a horizontal direction within the second coding area;
• or
• a coding area height that specifies a number of CTUs that are arranged in a vertical direction within the second coding area;
• and
• wherein the coding area indication data further includes at least one of:
• one or more area column stop flags for the second coding area, wherein, if the area column stop flag is set to a stop value, then the area column stop flag indicates a width of the second coding area;
• or
• one or more area line stop flags for the second coding area, wherein, if the area line stop flag is set to a stop value, then the area line stop flag indicates a height of the second coding area.

A method for decoding a picture, wherein the picture includes a plurality of coding tree units (CTUs) and a plurality of coding areas, with each coding area having one or more CTUs, the method comprising:

• deriving, for each coding area, a horizontal coding area boundary and a vertical coding area boundary, wherein:
• at least one of the horizontal coding area boundary or the vertical coding area boundary of a first coding area of the plurality of coding areas extends from a picture boundary of the picture to an opposing picture boundary of the picture;
• the plurality of coding areas includes the first coding area and a second coding area, wherein the first coding area encloses the second coding area within the first coding area;
• receiving coding area indication data, wherein the coding area indication data includes at least one of:
• a coding area width that specifies a number of CTUs that are arranged in a horizontal direction within the second coding area;
• or
• a coding area height that specifies a number of CTUs that are arranged in a vertical direction within the second coding area;
• and
• wherein the coding area indication data further includes at least one of:
• one or more area column stop flags for the second coding area, wherein, if the area column stop flag is set to a stop value, then the area column stop flag indicates the width of the second coding area;
• or
• one or more area line stop flags for the second coding area, wherein, if the area line stop flag is set to a stop value, then the area line stop flag indicates the height of the second coding area.

A method for encoding a picture, where the picture includes a plurality of coding tree units (CTUs) and a plurality of coding areas, with each coding area including one or more CTUs, the method comprising:

• setting, for each coding area, a horizontal coding area boundary and a vertical coding area boundary, wherein:
• at least one of the horizontal coding area boundary or the vertical coding area boundary of a first coding area of the plurality of coding areas extends from a picture boundary of the picture to an opposing picture boundary of the picture;
• and
• the plurality of coding areas includes the first coding area and a second coding area, wherein the first coding area encloses the second coding area within the first coding area;
• transmitting coding area indication data, wherein the coding area indication data includes at least one of:
• a coding area width that specifies a number of CTUs that are arranged in a horizontal direction within the second coding area;
• or
• a coding area height that specifies a number of CTUs that are arranged in a vertical direction within the second coding area;
• and
• wherein the coding area indication data further includes at least one of:
• one or more area column stop flags for the second coding area, wherein, if the area column stop flag is set to a stop value, then the area column stop flag indicates a width of the second coding area;
• or
• one or more area line stop flags for the second coding area, wherein, if the area line stop flag is set to a stop value, then the area line stop flag indicates a height of the second coding area.