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US 2026/0313147 A1Published application
Method and apparatus for video encoding/decoding using ibc mode, and method for transmitting bitstream
AssigneeNokia Technologies Oy
InventorHyeong Moon JANG
Life of this patent
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Abstract
An image decoding method is disclosed. The image decoding method includes determining a prediction mode of a current block based on prediction mode information of the current block obtained from a bitstream, obtaining a transform coefficient block of the current block from the bitstream, dequantizing the transform coefficient to generate a dequantized transform coefficient block, determining a transform kernel for the dequantized transform coefficient block, and generating a residual block of the current block by performing inverse transform on the dequantized transform coefficient block using the transform kernel.
Claims65
An image decoding method performed by an image decoding apparatus, the image decoding method comprising:
- determining a prediction mode of a current block based on prediction mode information of the current block obtained from a bitstream;
- obtaining a transform coefficient block of the current block from the bitstream;
- dequantizing the transform coefficient block to generate a dequantized transform coefficient block;
- determining a transform kernel for the dequantized transform coefficient block;
- and
- generating a residual block of the current block by performing inverse transform on the dequantized transform coefficient block using the transform kernel,
- wherein the transform kernel is determined based on transform kernel index information,
- wherein, the transform kernel index information specifies a combination of a horizontal transform kernel for the transform coefficient block and a vertical transform kernel for the transform coefficient block,
- wherein, in an instance in which the prediction mode of the current block is determined to be an intra block copy (IBC) mode which refers to a block located in a same picture as the current block and decoded before the current block, a value of the transform kernel index information is derived as a predetermined value rather than the transform kernel index information being obtained from the bitstream, and
- wherein, in an instance in which the prediction mode of the current block is an inter prediction mode or an intra prediction mode, the transform kernel index information is selectively obtained from the bitstream based on predetermined flag information in the bitstream.
7 more elements
An image decoding method performed by an image decoding apparatus, the image decoding method comprising:
- determining a prediction mode of a current block, based on prediction mode information of the current block obtained from a bitstream;
- obtaining a transform coefficient block of the current block from the bitstream;
- dequantizing the transform coefficient block to generate a dequantized transform coefficient block;
- determining a transform kernel for the dequantized transform coefficient block;
- and
- generating a residual block of the current block by performing inverse transform on the dequantized transform coefficient block based on the transform kernel,
- wherein the transform kernel is determined based on transform kernel index information,
- wherein the transform kernel index information specifies a combination of a horizontal transform kernel for the transform coefficient block and a vertical transform kernel for the transform coefficient block,
- wherein, in an instance in which the prediction mode of the current block is determined to be an intra block copy (IBC) mode which refers to a block located in a same picture as the current block and decoded before the current block, a value of the transform kernel index information is derived as a predetermined value rather than the transform kernel index information being obtained from the bitstream, regardless of predetermined flag information in the bitstream specifying whether explicit signaling of transform kernel index information is performed in the bitstream, and
- wherein, in an instance in which the prediction mode of the current block is a prediction mode other than the IBC mode, the transform kernel index information is obtained from the bitstream based on the predetermined flag information in the bitstream.
7 more elements
An image encoding method performed by an image encoding apparatus, the image encoding method comprising:
- selecting a prediction mode of a current block;
- generating a prediction block for the current block based on the selected prediction mode;
- generating a residual block for the current block based on the prediction block;
- selecting a transform kernel for transforming the residual block based on the prediction mode;
- transforming the residual block based on the transform kernel to generate a transform coefficient block;
- quantizing the transform coefficient block to generate a quantized transform coefficient block;
- and
- encoding the quantized transform coefficient block to generate a bitstream,
- wherein, in an instance in which the prediction mode of the current block is an intra block copy (IBC) mode which refers to a block located in a same picture as the current block and the block located in the same picture is encoded before the current block is encoded, the bitstream is encoded without including therein transform kernel index information of the transform kernel, regardless of whether predetermined flag information is encoded in the bitstream,
- wherein the predetermined flag information is configured to specify whether explicit signaling of transform kernel index information is performed via the bitstream,
- wherein the transform kernel index information is configured to specify a combination of a horizontal transform kernel for the transform coefficient block and a vertical transform kernel for the transform coefficient block,
- wherein a value of the transform kernel index information is derivable as a predetermined value, and
- wherein, in an instance in which the prediction mode of the current block is a prediction mode other than the IBC mode, the transform kernel index information of the transform kernel is encoded into the bitstream based on the predetermined flag information.
10 more elements
A method of transmitting a bitstream, the method comprising:
- obtaining the bitstream generated by performing at least:
- selecting a prediction mode of a current block;
- generating a prediction block for the current block based on the selected prediction mode;
- generating a residual block for the current block based on the prediction block;
- selecting a transform kernel for transforming the residual block based on the prediction mode;
- transforming the residual block based on the transform kernel to generate a transform coefficient block;
- quantizing the transform coefficient block to generate a quantized transform coefficient block;
- and
- encoding the quantized transform coefficient block to generate the bitstream,
- wherein, in an instance in which the prediction mode of the current block is an intra block copy (IBC) mode which refers to a block located in a same picture as the current block and the block located in the same picture is encoded before the current block is encoded, the bitstream is encoded without including therein transform kernel index information of the transform kernel, regardless of predetermined flag information being encoded in the bitstream,
- wherein the predetermined flag information is configured to specify whether explicit signaling of transform kernel index information is performed via the bitstream,
- wherein the transform kernel index information is configured to specify a combination of a horizontal transform kernel for the transform coefficient block and a vertical transform kernel for the transform coefficient block,
- wherein a value of the transform kernel index information is derivable as a predetermined value, and
- wherein, in an instance in which the prediction mode of the current block is a prediction mode other than the IBC mode, the transform kernel index information of the transform kernel is encoded into the bitstream based on the predetermined flag information;
- and
- transmitting the bitstream towards at least one image decoding apparatus.
13 more elements
A method of receiving and transmitting a bitstream, the method comprising:
- receiving, by an apparatus comprising a receiver and a transmitter, the bitstream via a network, the bitstream being generated by performing at least:
- selecting a prediction mode of a current block;
- generating a prediction block for the current block based on the selected prediction mode;
- generating a residual block for the current block based on the prediction block;
- selecting a transform kernel for transforming the residual block based on the prediction mode;
- transforming the residual block based on the transform kernel to generate a transform coefficient block;
- quantizing the transform coefficient block to generate a quantized transform coefficient block;
- and
- encoding the quantized transform coefficient block to generate the bitstream,
- wherein, in an instance in which the prediction mode of the current block is an intra block copy (IBC) mode which refers to a block located in a same picture as the current block and the block located in the same picture is encoded before the current block is encoded, the bitstream is encoded without including therein transform kernel index information of the transform kernel, regardless of predetermined flag information being encoded in the bitstream,
- wherein the predetermined flag information is configured to specify whether explicit signaling of transform kernel index information is performed via the bitstream,
- wherein the transform kernel index information is configured to specify a combination of a horizontal transform kernel for the transform coefficient block and a vertical transform kernel for the transform coefficient block,
- wherein a value of the transform kernel index information is derivable as a predetermined value, and
- wherein, in an instance in which the prediction mode of the current block is a prediction mode other than the IBC mode, the transform kernel index information of the transform kernel is encoded into the bitstream based on the predetermined flag information;
- storing, by the apparatus, the bitstream;
- and
- transmitting, by the apparatus, the bitstream towards at least one image decoding apparatus via the network.
14 more elements
A non-transitory computer-readable storage medium comprising program instructions stored therein that, when executed by at least one processor of an apparatus comprising a receiver and a transmitter, cause the apparatus to perform at least:
- receiving the bitstream via a network, the bitstream being generated by performing at least:
- selecting a prediction mode of a current block;
- generating a prediction block for the current block based on the selected prediction mode;
- generating a residual block for the current block based on the prediction block;
- selecting a transform kernel for transforming the residual block based on the prediction mode;
- transforming the residual block based on the transform kernel to generate a transform coefficient block;
- quantizing the transform coefficient block to generate a quantized transform coefficient block;
- and
- encoding the quantized transform coefficient block to generate the bitstream,
- wherein, in an instance in which the prediction mode of the current block is an intra block copy (IBC) mode which refers to a block located in a same picture as the current block and the block located in the same picture is encoded before the current block is encoded, the bitstream is encoded without including therein transform kernel index information of the transform kernel, regardless of predetermined flag information being encoded in the bitstream,
- wherein the predetermined flag information is configured to specify whether explicit signaling of transform kernel index information is performed via the bitstream,
- wherein the transform kernel index information is configured to specify a combination of a horizontal transform kernel for the transform coefficient block and a vertical transform kernel for the transform coefficient block,
- wherein a value of the transform kernel index information is derivable as a predetermined value, and
- wherein, in an instance in which the prediction mode of the current block is a prediction mode other than the IBC mode, the transform kernel index information of the transform kernel is encoded into the bitstream based on the predetermined flag information;
- storing the bitstream;
- and
- transmitting the bitstream towards at least one image decoding apparatus via the network.
14 more elements
An apparatus comprising:
- a receiver;
- a transmitter;
- at least one memory;
- and
- at least one processor,
- wherein the at least one processor is configured to cause the apparatus to:
- receive a bitstream via a network, the bitstream being generated by performing at least:
- selecting a prediction mode of a current block;
- generating a prediction block for the current block based on the selected prediction mode;
- generating a residual block for the current block based on the prediction block;
- selecting a transform kernel for transforming the residual block based on the prediction mode;
- transforming the residual block based on the transform kernel to generate a transform coefficient block;
- quantizing the transform coefficient block to generate a quantized transform coefficient block;
- and
- encoding the quantized transform coefficient block to generate the bitstream,
- wherein, in an instance in which the prediction mode of the current block is an intra block copy (IBC) mode which refers to a block located in a same picture as the current block and the block located in the same picture is encoded before the current block is encoded, the bitstream is encoded without including therein transform kernel index information of the transform kernel, regardless of predetermined flag information being encoded in the bitstream,
- wherein the predetermined flag information is configured to specify whether explicit signaling of transform kernel index information is performed via the bitstream,
- wherein the transform kernel index information is configured to specify a combination of a horizontal transform kernel for the transform coefficient block and a vertical transform kernel for the transform coefficient block,
- wherein a value of the transform kernel index information is derivable as a predetermined value, and
- wherein, in an instance in which the prediction mode of the current block is a prediction mode other than the IBC mode, the transform kernel index information of the transform kernel is encoded into the bitstream based on the predetermined flag information;
- store the bitstream;
- and
- transmit the bitstream towards at least one image decoding apparatus via the network.
20 more elements
Dependencies are inferred from the claim text.