| CPC H04N 19/186 (2014.11) [H04N 19/176 (2014.11); H04N 19/44 (2014.11); H04N 19/60 (2014.11); H04N 19/70 (2014.11)] | 20 Claims |

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1. A method comprising:
obtaining a current transform unit or a current sub-transform unit within the current transform unit, wherein a first chroma transform block and a second chroma transform block relate to the current transform unit or the current sub-transform unit;
performing a first determination to determine whether the first chroma transform block includes at least one transform coefficient levels not equal to 0;
obtaining a first value of a first flag based on a first result of the first determination, wherein the first flag specifies whether the first chroma transform block includes at least one transform coefficient levels not equal to 0;
performing a second determination to determine whether the second chroma transform block includes at least one transform coefficient levels not equal to 0;
obtaining a second value of a second flag based on a second result of the second determination, wherein the second flag specifies whether the second chroma transform block includes at least one transform coefficient levels not equal to 0;
signalling the first value of the first flag and the second value of the second flag in a transform unit syntax;
obtaining a third value of a third flag that specifies whether a transform tree structure is present or not; and
signalling the third value of the third flag in a coding unit syntax, wherein the first value of the first flag, the second value of the second flag and the third value of the third flag are used to derive a fourth value of a fourth flag that specifies whether a luma transform block includes at least one transform coefficient levels not equal to 0.
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