Method for encoding and decoding quantized matrix and apparatus using same

A video encoding method in an encoder, comprising:

• determining a quantization matrix to be used in a quantization and performing the quantization;
• determining a prediction method of the quantization matrix;
• encoding information about the quantization matrix in accordance with the prediction method of the quantization matrix;
• and
• outputting an encoded bitstream including the information about the quantization matrix,
• wherein the information about the quantization matrix is encoded in accordance with the prediction method of the quantization matrix, the prediction method of the quantization matrix being any one of a first prediction method or a second prediction method,
• wherein the information about the quantization matrix includes a prediction mode flag indicating one of the first prediction method or the second prediction method, the first prediction method specifying a method of deriving the quantization matrix by using information on a difference between the coefficient values of the quantization matrix and the second prediction method specifying a method of using a reference quantization matrix in the encoder,
• wherein in the encoding of the information about the quantization matrix in accordance with the first prediction method, the information about the quantization matrix is encoded to include the information on the difference between the coefficient values of the quantization matrix, whereby the coefficient values of the quantization matrix are derived based on the information on the difference between the coefficient values of the quantization matrix and an initial constant value,
• wherein in the encoding of the information about the quantization matrix in accordance with the second prediction method, the information about the quantization matrix is encoded to include identifying information indicating whether, as the quantization matrix, the reference quantization matrix is used or a default quantization matrix is used, and
• wherein the identifying information is used for
• a first function, as a value indicator, for indicating a difference value between a value for specifying a decoding target quantization matrix and a value for specifying the reference quantization matrix, and
• a second function, as a flag, for indicating that the quantization matrix is decoded from a default quantization matrix if a value of the identifying information is 0.

A non-transitory computer-readable storage medium storing a bitstream, the bitstream comprising:

• information about a quantization matrix, the quantization matrix being for reconstructing an encoded video,
• wherein the information about the quantization matrix is encoded in accordance with a prediction method of the quantization matrix, the prediction method of the quantization matrix being any one of a first prediction method or a second prediction method,
• wherein the information about the quantization matrix includes a prediction mode flag indicating one of the first prediction method or the second prediction method, the first prediction method specifying a method of deriving the quantization matrix by using information on a difference between the coefficient values of the quantization matrix and the second prediction method specifying a method of using a reference quantization matrix in a decoder,
• wherein in the encoding of the information about the quantization matrix in accordance with the first prediction method, the information about the quantization matrix is encoded to include the information on the difference between the coefficient values of the quantization matrix, whereby the coefficient values of the quantization matrix are derived based on the information on the difference between the coefficient values of the quantization matrix and an initial constant value,
• wherein in the encoding of the information about the quantization matrix in accordance with the second prediction method, the information about the quantization matrix is encoded to include identifying information indicating whether as the quantization matrix, the reference quantization matrix is used or a default quantization matrix is used, and
• wherein the identifying information is used for
• a first function, as a value indicator, for indicating a difference value between a value for specifying a decoding target quantization matrix and a value for specifying the reference quantization matrix, and
• a second function, as a flag, for indicating that the quantization matrix is decoded from a default quantization matrix if a value of the identifying information is 0.