Method, apparatus and system for encoding and decoding a transformed block of video samples

A method for encoding a coding unit according to a predetermined manner, comprising:

• determining the coding unit in a coding tree unit,
• determining a transform unit in the coding unit, and
• encoding the coding unit using the transform unit,
• wherein in the predetermined manner, a length of a side of the coding unit can be 128 samples,
• wherein, when a first constraint regarding a size of the transform unit is used to determine the transform unit, a maximum size selectable for luminance component of the transform unit in the coding unit is 32 samples which is one-fourth of 128 samples even if at least one side of the coding unit is 128 samples, wherein, a shape in which one side of a horizontal side and a vertical side is longer than other side is capable of being used as a shape of a transform unit in the predetermined manner,
• wherein the coding unit can be determined by dividing the coding tree unit using a ternary split,
• wherein a size of the coding tree unit is 128 samples by 128 samples, and
• wherein, when the coding unit spans a plurality of regions of 64 samples by 64 samples in the coding tree unit:
• a first transform unit of a plurality of transform units in the coding unit is included in a first region of the plurality of regions of 64 samples by 64 samples;
• a second transform unit, different from the first transform unit, of the plurality of transform units in the coding unit is included in a second region, different from the first region, of the plurality of regions of 64 samples by 64 samples;
• and
• the plurality of transform units are determined so that each transform unit of the plurality of transform units is included in any of the plurality of regions of 64 samples by 64 samples,
• wherein, the method further comprises:
• performing first and second tests to determine whether a cu_skip_flag is to be encoded,
• the first test including determining whether a current slice type is an intra slice, and
• the second test including comparison between a fixed threshold and at least one of a width and a height of the coding unit;
• and
• determining that the cu_skip_flag is to be encoded in a case where the current slice type is not the intra slice, a predetermined prediction mode is enabled, and the width and the height of the coding unit are equal to or less than the fixed threshold,
• wherein, the second test is performed after the first test in a case where it is determined, in the first test, that the current slice type is not the intra slice.

An apparatus for decoding a coding unit from a bitstream according to a predetermined manner, comprising:

• first decoding means for decoding information from the bitstream for determining the coding unit in a coding tree unit,
• first determining means for determining the coding unit based on the information,
• second determining means for determining a transform unit in the coding unit, and
• second decoding means for decoding the coding unit using the transform unit,
• wherein in the predetermined manner, a length of a side of the coding unit can be 128 samples,
• wherein, when a first constraint regarding a size of the transform unit is used to determine the transform unit, a maximum size selectable for luminance component of the transform unit in the coding unit is 32 samples which is one-fourth of 128 samples even if at least one side of the coding unit is 128 samples,
• wherein, a shape in which one side of a horizontal side and a vertical side is longer than other side is capable of being used as a shape of a transform unit in the predetermined manner,
• wherein the coding unit can be determined by dividing the coding tree unit using a ternary split,
• wherein a size of the coding tree unit is 128 samples by 128 samples, and
• wherein, when the coding unit spans a plurality of regions of 64 samples by 64 samples in the coding tree unit:
• a first transform unit of a plurality of transform units in the coding unit is included in a first region of the plurality of regions of 64 samples by 64 samples;
• a second transform unit, different from the first transform unit, of the plurality of transform units in the coding unit is included in a second region, different from the first region, of the plurality of regions of 64 samples by 64 samples;
• and
• the plurality of transform units are determined so that each transform unit of the plurality of transform units is included in any of the plurality of regions of 64 samples by 64 samples,
• performing means for performing first and second tests to determine whether a cu_skip_flag is to be decoded, the first test including determining whether a current slice type is an intra slice, and the second test including comparison between a fixed threshold and at least one of a width and a height of the coding unit;
• and
• determining means for determining that the cu_skip_flag is to be decoded in a case where the current slice type is not the intra slice, a predetermined prediction mode is enabled, and the width and the height of the coding unit are equal to or less than the fixed threshold,
• wherein, the second test is performed after the first test in a case where it is determined, in the first test, that the current slice type is not the intra slice.

An apparatus for encoding a coding unit according to a predetermined manner, comprising:

• first determining means for determining the coding unit in a coding tree unit,
• second determining means for determining a transform unit in the coding unit, and
• encoding means for encoding the coding unit using the transform unit, wherein in the predetermined manner, a length of a side of the coding unit can be 128 samples,
• wherein, when a first constraint regarding a size of the transform unit is used to determine the transform unit, a maximum size selectable for luminance component of the transform unit in the coding unit is 32 samples which is one-fourth of 128 samples even if at least one side of the coding unit is 128 samples,
• wherein, a shape in which one side of a horizontal side and a vertical side is longer than other side is capable of being used as a shape of a transform unit in the predetermined manner,
• wherein the coding unit can be determined by dividing the coding tree unit using a ternary split,
• wherein a size of the coding tree unit is 128 samples by 128 samples, and
• wherein, when the coding unit spans a plurality of regions of 64 samples by 64 samples in the coding tree unit:
• a first transform unit of a plurality of transform units in the coding unit is included in a first region of the plurality of regions of 64 samples by 64 samples;
• a second transform unit, different from the first transform unit, of the plurality of transform units in the coding unit is included in a second region, different from the first region, of the plurality of regions of 64 samples by 64 samples;
• and
• the plurality of transform units are determined so that each transform unit of the plurality of transform units is included in any of the plurality of regions of 64 samples by 64 samples,
• performing means for performing first and second tests to determine whether a cu_skip_flag is to be encoded, the first test including determining whether a current slice type is an intra slice, and the second test including comparison between a fixed threshold and at least one of a width and a height of the coding unit;
• and
• determining means for determining that the cu_skip_flag is to be encoded in a case where the current slice type is not the intra slice, a predetermined prediction mode is enabled, and the width and the height of the coding unit are equal to or less than the fixed threshold,
• wherein, the second test is performed after the first test in a case where it is determined, in the first test, that the current slice type is not the intra slice.

A non-transitory computer-readable storage medium storing a program for causing a computer to execute an image decoding method for decoding a coding unit from a bitstream according to a predetermined manner, the method comprising:

• decoding information from the bitstream for determining the coding unit in a coding tree unit,
• determining the coding unit based on the information,
• determining a transform unit in the coding unit, and
• decoding the coding unit using the transform unit,
• wherein in the predetermined manner, a length of a side of the coding unit can be 128 samples,
• wherein, when a first constraint regarding a size of the transform unit is used to determine the transform unit, a maximum size selectable for luminance component of the transform unit in the coding unit is 32 samples which is one-fourth of 128 samples even if at least one side of the coding unit is 128 samples,
• wherein, a shape in which one side of a horizontal side and a vertical side is longer than other side is capable of being used as a shape of a transform unit in the predetermined manner,
• wherein the coding unit can be determined by dividing the coding tree unit using a ternary split,
• wherein a size of the coding tree unit is 128 samples by 128 samples, and
• wherein, when the coding unit spans a plurality of regions of 64 samples by 64 samples in the coding tree unit:
• a first transform unit of a plurality of transform units in the coding unit is included in a first region of the plurality of regions of 64 samples by 64 samples;
• a second transform unit, different from the first transform unit, of the plurality of transform units in the coding unit is included in a second region, different from the first region, of the plurality of regions of 64 samples by 64 samples;
• and
• the plurality of transform units are determined so that each transform unit of the plurality of transform units is included in any of the plurality of regions of 64 samples by 64 samples,
• wherein, the method further comprises:
• performing first and second tests to determine whether a cu_skip_flag is to be decoded, the first test including determining whether a current slice type is an intra slice, and the second test including comparison between a fixed threshold and at least one of a width and a height of the coding unit;
• and
• determining that the cu_skip_flag is to be decoded in a case where the current slice type is not the intra slice, a predetermined prediction mode is enabled, and the width and the height of the coding unit are equal to or less than the fixed threshold,
• wherein, the second test is performed after the first test in a case where it is determined, in the first test, that the current slice type is not the intra slice.

A non-transitory computer-readable storage medium storing a program for causing a computer to execute a method for encoding a coding unit according to a predetermined manner, the method comprising:

• determining the coding unit in a coding tree unit,
• determining a transform unit in the coding unit, and
• encoding the coding unit using the transform unit,
• wherein in the predetermined manner, a length of a side of the coding unit can be 128 samples,
• wherein, when a first constraint regarding a size of the transform unit is used to determine the transform unit, a maximum size selectable for luminance component of the transform unit in the coding unit is 32 samples which is one-fourth of 128 samples even if at least one side of the coding unit is 128 samples,
• wherein, a shape in which one side of a horizontal side and a vertical side is longer than other side is capable of being used as a shape of a transform unit in the predetermined manner,
• wherein the coding unit can be determined by dividing the coding tree unit using a ternary split,
• wherein a size of the coding tree unit is 128 samples by 128 samples, and
• wherein, when the coding unit spans a plurality of regions of 64 samples by 64 samples in the coding tree unit:
• a first transform unit of a plurality of transform units in the coding unit is included in a first region of the plurality of regions of 64 samples by 64 samples;
• a second transform unit, different from the first transform unit, of the plurality of transform units in the coding unit is included in a second region, different from the first region, of the plurality of regions of 64 samples by 64 samples;
• and
• the plurality of transform units are determined so that each transform unit of the plurality of transform units is included in any of the plurality of regions of 64 samples by 64 samples,
• wherein, the method further comprises:
• performing first and second tests to determine whether a cu_skip_flag is to be encoded, the first test including determining whether a current slice type is an intra slice, and the second test including comparison between a fixed threshold and at least one of a width and a height of the coding unit;
• and
• determining that the cu_skip_flag is to be encoded in a case where the current slice type is not the intra slice, a predetermined prediction mode is enabled, and the width and the height of the coding unit are equal to or less than the fixed threshold,
• wherein, the second test is performed after the first test in a case where it is determined, in the first test, that the current slice type is not the intra slice.