Mixed NAL unit type based-video encoding/decoding method and apparatus, and method for transmitting bitstream

An image encoding method performed by an image encoding apparatus, the image encoding method comprising:

• partitioning a current picture into one or more subpictures;
• determining a network abstraction layer (NAL) unit type of each of a plurality of slices included in the one or more subpictures;
• and
• encoding the plurality of slices based on the determined NAL unit type,
• wherein the current picture includes a first subpicture and a second subpicture having different NAL unit types, based on at least some of the plurality of slices having different NAL unit types, and
• wherein a NAL unit type of the second subpicture is determined based on a NAL unit type of the first subpicture.

A non-transitory computer-readable recording medium storing a bitstream generated by an image encoding method, the image encoding method comprising:

• partitioning a current picture into one or more subpictures;
• determining a network abstraction layer (NAL) unit type of each of a plurality of slices included in the one or more subpictures;
• and
• encoding the plurality of slices based on the determined NAL unit type,
• wherein the current picture includes a first subpicture and a second subpicture having different NAL unit types, based on at least some of the plurality of slices having different NAL unit types, and
• wherein a NAL unit type of the second subpicture is determined based on a NAL unit type of the first subpicture.

A method of transmitting a bitstream generated by an image encoding method, the image encoding method comprising:

• partitioning a current picture into one or more subpictures;
• determining a network abstraction layer (NAL) unit type of each of a plurality of slices included in the one or more subpictures;
• and
• encoding the plurality of slices based on the determined NAL unit type,
• wherein the current picture includes a first subpicture and a second subpicture having different NAL unit types, based on at least some of the plurality of slices having different NAL unit types, and
• wherein a NAL unit type of the second subpicture is determined based on a NAL unit type of the first subpicture.