| CPC H04N 19/124 (2014.11) [H04N 19/105 (2014.11); H04N 19/117 (2014.11); H04N 19/122 (2014.11); H04N 19/13 (2014.11); H04N 19/15 (2014.11); H04N 19/157 (2014.11); H04N 19/159 (2014.11); H04N 19/186 (2014.11); H04N 19/43 (2014.11); H04N 19/46 (2014.11); H04N 19/463 (2014.11); H04N 19/61 (2014.11); H04N 19/174 (2014.11); H04N 19/176 (2014.11)] | 4 Claims |

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1. A video decoding apparatus comprising:
an inverse-quantizer configured to identify a quantization group, the quantization group being a group of a plurality of transform blocks to which a same chrominance component quantization parameter is applied, configured to calculate the chrominance component quantization parameter to be applied to the quantization group, configured to inverse-quantize transform coefficients of a transform block included in the quantization group by using the calculated chrominance component quantization parameter;
an inverse-transformer configured to generate a residual block of a current block by inverse-transforming the inverse-quantized transform coefficients;
a predictor configured to generate a prediction block of the current block by predicting the current block; and
an adder configured to reconstruct the current block based on the residual block and the prediction block,
wherein the quantization group comprises transform blocks of a first size and transform blocks of a second size,
wherein the inverse-quantizer comprises:
a chrominance component quantization parameter index calculator configured to calculate a chrominance component quantization parameter index by using a chrominance component quantization parameter offset, wherein the chrominance component quantization parameter offset is derived from encoding information of a level of a sequence; and
a chrominance component quantization parameter calculator configured to calculate the chrominance component quantization parameter based on the chrominance component quantization parameter index.
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