Image decoding method for coding DPB parameter, and device therefor
A method by which a decoding device decodes an image, according to the present document, comprises the steps of: acquiring image information including decoded picture buffer (DPB) parameter information and an output layer set (OLS) DPB parameter index for a target OLS; deriving the DPB parameter information about the target OLS on the basis of the OLS DPB parameter index; updating a DPB on the basis of the DPB parameter information about the target OLS; and decoding the current picture on the basis of the updated DPB.
1 . An image decoding apparatus comprising:
a memory; and
at least one processor connected to the memory, the at least one processor configured to:
obtain image information including Decoded Picture Buffer (DPB) parameter information and an Output Layer Set (OLS) DPB parameter index for a target OLS, the OLS DPB parameter index being obtained from a Video Parameter Set (VPS);
derive DPB parameter information for the target OLS based on the OLS DPB parameter index;
update a DPB based on the DPB parameter information for the target OLS; and
decode a current picture based on the updated DPB,
wherein the OLS DPB parameter index specifies the DPB parameter information applied to a multi-layer OLS,
wherein the obtaining of the OLS DPB parameter index is performed for the multi-layer OLS that includes two or more layers, and
wherein the obtaining of the OLS DPB parameter index from the VPS is skipped for an OLS that includes only one layer.
2 . The apparatus of claim 1 , wherein the DPB parameter information is included in the VPS.
3 . The apparatus of claim 1 , wherein the DPB parameter information for the target OLS includes information on DPB size, information on maximum picture reorder number of the DPB for the target OLS and information on maximum latency of the DPB.
4 . An image encoding apparatus comprising:
a memory; and
at least one processor connected to the memory, the at least one processor configured to:
generate Decoded Picture Buffer (DPB) parameter information;
generate an Output Layer Set (OLS) DPB parameter index for DPB parameter information of a target OLS; and
encode image information including the OLS DPB parameter index and the DPB parameter information, the OLS DPB parameter index being encoded into a Video Parameter Set (VPS),
wherein the OLS DPB parameter index specifies the DPB parameter information applied to a multi-layer OLS,
wherein the generating of the OLS DPB parameter index is performed for the multi-layer OLS that includes two or more layers, and
wherein the encoding of the OLS DPB parameter index into the VPS is skipped for an OLS that includes only one layer.
5 . The apparatus of claim 4 , wherein the DPB parameter information is included in the VPS.
6 . An apparatus for transmitting a bitstream for an image, the apparatus comprising:
at least one processor configured to obtain the bitstream generated by an encoding apparatus; and
a transmitter configured to transmit the bitstream;
the bitstream is generated by:
generating Decoded Picture Buffer (DPB) parameter information;
generating an Output Layer Set (OLS) DPB parameter index for DPB parameter information of a target OLS; and
encoding image information including the OLS DPB parameter index and the DPB parameter information, the OLS DPB parameter index being encoded into a Video Parameter Set (VPS),
wherein the OLS DPB parameter index specifies the DPB parameter information applied to a multi-layer OLS,
wherein the generating of the OLS DPB parameter index is performed for the multi-layer OLS that includes two or more layers, and
wherein the encoding of the OLS DPB parameter index into the VPS is skipped for an OLS that includes only one layer.