Image decoding method associated with transform skip residual coding, and device therefor
An image decoding method carried out by a decoding device, according to the present document, comprises the steps of: acquiring prediction-related information for a current block; acquiring a dependent quantization enable flag related to whether dependent quantization is available; acquiring, on the basis of the dependent quantization enable flag, a transform skip residual coding (TSRC) enable flag related to whether TSRC is available; acquiring residual information of residual coding syntax for the current block, which has been derived on the basis of the TSRC enable flag; deriving motion information of the current block on the basis of the prediction-related information; deriving a prediction sample of the current block on the basis of the motion information; deriving a residual sample of the current block on the basis of the residual information; and generating a reconstructed picture on the basis of the prediction sample and the residual sample.
1. An image decoding method performed by a decoding apparatus, the image decoding method comprising:
obtaining prediction related information for a current block;
obtaining a dependent quantization enabled flag,
wherein the dependent quantization enabled flag having a value of 1 represents that dependent quantization is enabled, and the dependent quantization enabled flag having a value of 0 represents that dependent quantization is not enabled;
obtaining a Transform Skip (TS) residual coding disabled flag,
wherein the TS residual coding disabled flag having a value of 1 represents that TS residual coding is not enabled, and the TS residual coding disabled flag having the value of 0 represents that the TS residual coding is enabled;
obtaining residual information for the current block based on the TS residual coding disabled flag;
deriving motion information of the current block based on the prediction related information;
deriving a prediction sample of the current block based on the motion information;
deriving a residual sample of the current block based on the residual information; and
generating a reconstructed picture based on the prediction sample and the residual sample,
wherein each of the dependent quantization enabled flag and the TS residual coding disabled flag is signaled based on a picture header syntax or a slice header syntax,
wherein, based on a value of the obtained dependent quantization enabled flag and a value of the obtained TS residual coding disabled flag, whether a state of the dependent quantization is derived or not is determined,
wherein, in response to the value of the obtained dependent quantization enabled flag being 1 and the value of the obtained TS residual coding disabled flag being 0, the state of the dependent quantization is derived and a value of a transform coefficient is derived based on the state of the dependent quantization, and
wherein, in response to the value of the obtained TS residual coding disabled flag being 1, the state of the dependent quantization is not derived and a value of a transform coefficient is derived without the state of the dependent quantization.
2. An image encoding method performed by an encoding apparatus, the image encoding method comprising:
deriving a prediction sample of a current block based on an inter prediction;
encoding prediction related information for the current block;
encoding a dependent quantization enabled flag,
wherein the dependent quantization enabled flag having a value of 1 represents that dependent quantization is enabled, and the dependent quantization enabled flag having a value of 0 represents that dependent quantization is not enabled;
encoding a Transform Skip (TS) residual coding disabled flag,
wherein the TS residual coding disabled flag having a value of 1 represents that TS residual coding is not enabled, and the TS residual coding disabled flag having the value of 0 represents that the TS residual coding is enabled;
encoding residual information for the current block; and
generating a bitstream including the prediction related information, the dependent quantization enabled flag, the TS residual coding disabled flag and the residual information,
wherein each of the dependent quantization enabled flag and the TS residual coding disabled flag is signaled based on a picture header syntax or a slice header syntax,
wherein, based on a value of the obtained dependent quantization enabled flag and a value of the obtained TS residual coding disabled flag, whether a state of the dependent quantization is derived or not is determined,
wherein, in response to the value of the obtained dependent quantization enabled flag being 1 and the value of the obtained TS residual coding disabled flag being 0, the state of the dependent quantization is derived and a value of a transform coefficient is derived based on the state of the dependent quantization, and
wherein, in response to the value of the obtained TS residual coding disabled flag being 1, the state of the dependent quantization is not derived and a value of a transform coefficient is derived without the state of the dependent quantization.
3. A transmission method for data comprising a bitstream of image information, the transmission method comprising:
obtaining the bitstream of the image information including residual information, wherein the bitstream is generated by deriving a prediction sample of a current block based on an inter prediction, encoding prediction related information for the current block, encoding a dependent quantization enabled flag, encoding a Transform Skip (TS) residual coding disabled flag, encoding the residual information for the current block and generating the bitstream including the prediction related information, the dependent quantization enabled flag, the TS residual coding disabled flag and the residual information; and
transmitting the data comprising the bitstream of the image information including the residual information,
wherein the dependent quantization enabled flag having a value of 1 represents that dependent quantization is enabled, and the dependent quantization enabled flag having a value of 0 represents that dependent quantization is not enabled,
wherein the TS residual coding disabled flag having a value of 1 represents that TS residual coding is not enabled, and the TS residual coding disabled flag having the value of 0 represents that the TS residual coding is enabled,
wherein each of the dependent quantization enabled flag and the TS residual coding disabled flag is signaled based on a picture header syntax or a slice header syntax,
wherein, based on a value of the obtained dependent quantization enabled flag and a value of the obtained TS residual coding disabled flag, whether a state of the dependent quantization is derived or not is determined,
wherein, in response to the value of the obtained dependent quantization enabled flag being 1 and the value of the obtained TS residual coding disabled flag being 0, the state of the dependent quantization is derived and a value of a transform coefficient is derived based on the state of the dependent quantization, and
wherein, in response to the value of the obtained TS residual coding disabled flag being 1, the state of the dependent quantization is not derived and a value of a transform coefficient is derived without the state of the dependent quantization.