Granted Patent B2

US 12,519,957 · App. 18/767,755 · Granted Jan 6, 2026

Inventors: Christopher James Rosewarne (Concord, AU); Iftekhar Ahmed (Lane Cove North, AU)

Assignee: Canon Kabushiki Kaisha

H04N19/174H04N19/124H04N19/46H04N19/70H04N19/96

Abstract

Claims (58)

1 . A method of decoding an image including a plurality of coding tree units each comprising one or more coding units from a bitstream using a predetermined manner, the method comprising:

determining a subdivision value for determining a quantisation group in which one quantisation parameter delta is shared, the one quantisation parameter delta representing difference between a quantisation parameter for the quantisation group and a predicted quantisation parameter of the quantisation parameter for the quantisation group, the subdivision value being a value that increases as a number of times a coding tree unit is split into coding units increases, a quad split being capable of being used for splitting into coding units, and the quantisation group being capable of including a plurality of coding units;

decoding a predetermined syntax element from the bitstream;

determining a maximum subdivision value for determining the quantisation group according to the predetermined syntax element;

determining the quantisation group by comparing the subdivision value and the maximum subdivision value;

decoding the one quantisation parameter delta for the quantisation group;

deriving the quantisation parameter for the quantisation group according to the one quantisation parameter delta and the predicted quantisation parameter of the quantisation parameter for the quantisation group; and

decoding one or more coding units included in the quantisation group using the quantisation parameter for the quantisation group,

wherein the maximum subdivision value is limited to a range depending on a first syntax element included in a sequence parameter set of the bitstream, in a case where a slice type is an intra slice and a value of a partition constraint override flag is a first value,

wherein the maximum subdivision value is limited to a range depending on a second syntax element included in the sequence parameter set of the bitstream, in a case where a slice type is a P slice or a B slice which is capable of using inter prediction and the value of the partition constraint override flag is the first value,

wherein the maximum subdivision value is limited to a range depending on a syntax element which is different from the first and second syntax elements and is capable of being included in a slice header of the bitstream in the predetermined manner, in a case where the value of the partition constraint override flag is a second value different from the first value, and

wherein the predetermined syntax element for determining the maximum subdivision value is capable of being included in the slice header of the bitstream in the predetermined manner regardless of the value of the partition constraint override flag.

2 . The method according to claim 1 , wherein the first syntax element is a syntax element of a max_mtt_hierarchy_depth for the intra slice and the second syntax element is a syntax element of a max_mtt_hierarchy_depth for the P slice and the B slice.

3 . The method according to claim 1 ,

wherein the predetermined syntax element is a syntax element of a cu_qp_delta_subdiv.

4 . The method according to claim 1 , wherein the partition constraint override flag indicates whether partition constraint parameters signaled in the sequence parameter set are to be overridden, and the partition constraint override flag, having the second value, indicates that the partition constraint parameters signaled in the sequence parameter set are to be overridden.

5 . The method according to claim 4 , the partition constraint parameters signaled in the sequence parameter set includes the first syntax element and the second syntax element.

6 . A method of encoding an image including a plurality of coding tree units each comprising one or more coding units into a bitstream using a predetermined manner, the method comprising:

determining a subdivision value for determining a quantisation group in which one quantisation parameter delta is shared, the one quantisation parameter delta representing difference between a quantisation parameter for the quantisation group and a predicted quantisation parameter of the quantisation parameter for the quantisation group, the subdivision value being a value that increases as a number of times a coding tree unit is split into coding units increases, a quad split being capable of being used for splitting into coding units, and the quantisation group being capable of including a plurality of coding units;

determining a maximum subdivision value for determining the quantisation group;

encoding, into the bitstream, a predetermined syntax element for determining the maximum subdivision value in a method of decoding which decodes the bitstream;

determining the quantisation group by comparing the subdivision value and the maximum subdivision value;

encoding the one quantisation parameter delta for the quantisation group into the bitstream; and

encoding one or more coding units included in the quantisation group using the quantisation parameter for the quantisation group,

wherein the maximum subdivision value is limited to a range depending on a first syntax element included in a sequence parameter set of the bitstream, in a case where a slice type is an intra slice and a value of a partition constraint override flag is a first value,

wherein the maximum subdivision value is limited to a range depending on a second syntax element included in the sequence parameter set of the bitstream, in a case where a slice type is a P slice or a B slice which is capable of using inter prediction and the value of the partition constraint override flag is the first value,

wherein the maximum subdivision value is limited to a range depending on a syntax element which is different from the first and second syntax elements and is capable of being included in a slice header of the bitstream in the predetermined manner, in a case where the value of the partition constraint override flag is a second value different from the first value, and

wherein the predetermined syntax element for determining the maximum subdivision value is capable of being included in the slice header of the bitstream in the predetermined manner regardless of the value of the partition constraint override flag.

7 . The method according to claim 6 ,

wherein the first syntax element is a syntax element of a max_mtt_hierarchy_depth for the intra slice and the second syntax element is a syntax element of a max_mtt_hierarchy_depth for the P slice and the B slice.

8 . The method according to claim 6 ,

wherein, the predetermined syntax element is a syntax element of a cu_qp_delta_subdiv.

9 . The method according to claim 6 , wherein the partition constraint override flag indicates whether partition constraint parameters signaled in the sequence parameter set are to be overridden, and the partition constraint override flag, having the second value, indicates that the partition constraint parameters signaled in the sequence parameter set are to be overridden.

10 . The method according to claim 9 , the partition constraint parameters signaled in the sequence parameter set includes the first syntax element and the second syntax element.

11 . An apparatus for decoding an image including a plurality of coding tree units each comprising one or more coding units from a bitstream using a predetermined manner, the apparatus comprising:

a first determining unit configured to determine a subdivision value for determining a quantisation group in which one quantisation parameter delta is shared, the one quantisation parameter delta representing difference between a quantisation parameter for the quantisation group and a predicted quantisation parameter of the quantisation parameter for the quantisation group, the subdivision value being a value that increases as a number of times a coding tree unit is split into coding units increases, a quad split being capable of being used for splitting into coding units, and the quantisation group being capable of including a plurality of coding units;

a first decoding unit configured to decode a predetermined syntax element from the bitstream;

a second determining unit configured to determine a maximum subdivision value for determining the quantisation group according to the predetermined syntax element;

a third determining unit configured to determine the quantisation group by comparing the subdivision value and the maximum subdivision value;

a second decoding unit configured to decode the one quantisation parameter delta for the quantisation group; and

a deriving unit configured to derive the quantisation parameter for the quantisation group according to the one quantisation parameter delta and the predicted quantisation parameter of the quantisation parameter for the quantisation group,

wherein the decoding unit is configured to decode one or more coding units included in the quantisation group using the quantisation parameter for the quantisation group,

wherein the maximum subdivision value is limited to a range depending on a first syntax element included in a sequence parameter set of the bitstream, in a case where a slice type is an intra slice and a value of a partition constraint override flag is a first value,

wherein the maximum subdivision value is limited to a range depending on a second syntax element included in the sequence parameter set of the bitstream, in a case where a slice type is a P slice or a B slice which is capable of using inter prediction and the value of the partition constraint override flag is the first value,

wherein the maximum subdivision value is limited to a range depending on a syntax element which is different from the first and second syntax elements and is capable of being included in a slice header of the bitstream in the predetermined manner, in a case where the value of the partition constraint override flag is a second value different from the first value, and

wherein the predetermined syntax element for the maximum subdivision value is capable of being included in the slice header of the bitstream in the predetermined manner regardless of the value of the partition constraint override flag.

12 . An apparatus for encoding an image including a plurality of coding tree units each comprising one or more coding units into a bitstream using a predetermined manner, the apparatus comprising:

a first determining unit configured to determine a subdivision value for determining a quantisation group in which one quantisation parameter delta is shared, the one quantisation parameter delta representing difference between a quantisation parameter for the quantisation group and a predicted quantisation parameter of the quantisation parameter for the quantisation group, the subdivision value being a value that increases as a number of times a coding tree unit is split into coding units increases, a quad split being capable of being used for splitting into coding units, and the quantisation group being capable of including a plurality of coding units;

a second determining unit configured to determine a maximum subdivision value for determining the quantisation group;

an encoding unit configured to encode, into the bitstream, a predetermined syntax element for determining the maximum subdivision value in a method of decoding which decodes the bitstream; and

a third determining unit configured to determine the quantisation group by comparing the subdivision value and the maximum subdivision value, wherein the encoding unit is configured to encode the one quantisation parameter delta for the quantisation group,

wherein the encoding unit is configured to encode one or more coding units included in the quantisation group using the quantisation parameter for the quantisation group,

wherein the maximum subdivision value is limited to a range depending on a first syntax element included in a sequence parameter set of the bitstream, in a case where a slice type is an intra slice and a value of a partition constraint override flag is a first value,

wherein the maximum subdivision value is limited to a range depending on a second syntax element included in the sequence parameter set of the bitstream, in a case where a slice type is a P slice or a B slice which is capable of using inter prediction and the value of the partition constraint override flag is the first value,

wherein the maximum subdivision value is limited to a range depending on a syntax element which is different from the first and second syntax elements and is capable of being included in a slice header of the bitstream in the predetermined manner, in a case where the value of the partition constraint override flag is a second value different from the first value, and

wherein the predetermined syntax element for determining the maximum subdivision value is capable of being included in the slice header of the bitstream in the predetermined manner regardless of the value of the partition constraint override flag.

13 . The method according to claim 4 , wherein the syntax element which is different from the first and second syntax elements is included in a data structure which is different from the sequence parameter set, in a case where the syntax element which is different from the first and second syntax elements is not included in the slice header.

14 . The method according to claim 9 , wherein, the syntax element which is different from the first and second syntax elements is included in a data structure which is different from the sequence parameter set, in a case where the syntax element which is different from the first and second syntax elements is not included in the slice header.

Priority Claims (1)

Continuity (2)

References Cited (14)