Method and apparatus for decoded picture buffer management in video coding system using intra block copy

An apparatus for managing a DPB (decoded picture buffer) in a video coding system, wherein the video coding system uses coding modes including an Inter prediction mode and an IntraBC (Intra Block Copy) mode, comprising one or more electronic circuits or processors arranged to:

• determine whether the IntraBC mode is used for a current picture, wherein decoded data of the current picture is used as reference data for the current picture if the current picture is coded using the IntraBC mode;
• allocate a maximum allowed number of decoded pictures in the DPB based on whether the IntraBC mode is used for the current picture;
• and
• encode or decode the current picture using decoded pictures stored in the DPB as reference data, wherein a total number of decoded pictures in the DPB is equal to or less than the maximum allowed number of decoded pictures in the DPB.

A method of managing a DPB (decoded picture buffer) for a video coding system allowing multiple colour formats, comprising:

• determining a target total memory size for storing a target maximum number of decoded pictures in the DPB at a target resolution in a target colour format;
• determining a scaling factor for current pictures having the same target resolution, but in a second colour format different from the target colour format;
• allocating a second maximum number of second decoded pictures in the DPB for the current pictures according to the target maximum number of decoded pictures scaled by the scaling factor, wherein the scaling factor is smaller than 1 for at least one second colour format;
• and
• encoding or decoding the current picture using second decoded pictures stored in the DPB as reference data, wherein a total number of second decoded pictures in the DPB is equal to or less than the second maximum number of second decoded pictures in the DPB.

An apparatus for managing a DPB (decoded picture buffer) in a video coding system allowing multiple colour formats, comprising one or more electronic circuits or processors arranged to:

• determine a target total memory size for storing a target maximum number of decoded pictures in the DPB at a target resolution in a target colour format;
• determine a scaling factor for current pictures having the same target resolution, but in a second colour format different from the target colour format;
• allocate a second maximum number of second decoded pictures in the DPB for the current pictures according to the target maximum number of decoded pictures scaled by the scaling factor, wherein the scaling factor is smaller than 1 for at least one second colour format;
• and
• encode or decode the current picture using second decoded pictures stored in the DPB as reference data, wherein a total number of second decoded pictures in the DPB is equal to or less than the second maximum number of second decoded pictures in the DPB.

A method of managing a DPB (decoded picture buffer) for a video coding system, wherein the video coding system uses coding modes including an Inter prediction mode and an IntraBC (Intra Block Copy) mode, comprising:

• determining whether the IntraBC mode is used for a current picture, wherein decoded data of the current picture is used as reference data for the current picture if the current picture is coded using the IntraBC mode;
• determining a maximum number of reordered pictures in the DPB, wherein the maximum number of reordered pictures indicates a maximum allowed number of pictures with an output-picture flag equal to 1 that can precede any selected picture with the output-picture flag equal to 1 in a CVS (coded video sequence) in a decoding order and follow said any selected picture with the output-picture flag equal to 1 in an output order;
• emptying one or more decoded pictures stored in the DPB if one or more conditions are true, wherein said one or more conditions include a first condition corresponding to a number of decoded pictures in the DPB marked as “needed for output” being greater than the maximum number of reordered picture modified according to whether the IntraBC mode is used for the current picture;
• and
• encoding or decoding the current picture using decoded pictures stored in the DPB as reference data, wherein a total number of decoded pictures in the DPB is equal to or less than a maximum allowed number of decoded pictures in the DPB.

An apparatus for managing a DPB (decoded picture buffer) in a video coding system, wherein the video coding system uses coding modes including an Inter prediction mode and an IntraBC (Intra Block Copy) mode, comprising one or more electronic circuits or processors arranged to:

• determine whether the IntraBC mode is used for a current picture, wherein decoded data of the current picture is used as reference data for the current picture if the current picture is coded using the IntraBC mode;
• determine a maximum number of reordered pictures in the DPB, wherein the maximum number of reordered pictures indicates a maximum allowed number of pictures with an output-picture flag equal to 1 that can precede any selected picture with the output-picture flag equal to 1 in a CVS (coded video sequence) in a decoding order and follow said any selected picture with the output-picture flag equal to 1 in an output order;
• empty one or more decoded pictures stored in the DPB if one or more conditions are true, wherein said one or more conditions include a first condition corresponding to a number of decoded pictures in the DPB marked as “needed for output” being greater than the maximum number of reordered picture modified according to whether the IntraBC mode is used for the current picture;
• and
• encode or decode the current picture using decoded pictures stored in the DPB as reference data, wherein a total number of decoded pictures in the DPB is equal to or less than a maximum allowed number of decoded pictures in the DPB.