In-loop filtering method and apparatus for same

1. A video decoding method, by a decoding apparatus, comprising:

receiving video information;

identifying that an intra pulse code modulation (I_PCM) mode is not applied to a current block in a current picture based on the video information;

generating a reconstructed picture including a reconstructed block of the current block based on the video information;

determining that a deblocking filter is to be applied to the reconstructed block based on a result of the identification;

determining that a sample adaptive offset (SAO) is to be applied to the reconstructed block based on the result of the identification; and

generating a modified reconstructed picture based on the reconstructed picture and results of the determinations,

wherein the modified reconstructed picture is generated based on the deblocking filter and the SAO on the reconstructed picture,

wherein the SAO is used after the deblocking filter on the reconstructed picture,

wherein a first clipping is applied to a first output of the deblocking filter,

wherein a second clipping is applied to a second output of the SAO, and

wherein the clipped first output is used as an input of the SAO.

2. A video encoding method, by an encoding apparatus, comprising:

identifying that an intra pulse code modulation (I_PCM) mode is not applied to a current block in a current picture;

generating a reconstructed picture including a reconstructed block of the current block based on a result of the identification;

determining that a deblocking filter is to be applied to the reconstructed block based on the result of the identification;

determining that a sample adaptive offset (SAO) is to be applied to the reconstructed block based on the result of the identification;

generating a modified reconstructed picture based on the reconstructed picture and results of the determinations; and

outputting video information including information indicating whether the intra pulse code modulation mode is applied to the current block

wherein the modified reconstructed picture is generated based on the deblocking filter and the SAO on the reconstructed picture,

wherein the SAO is used after the deblocking filter on the reconstructed picture,

wherein a first clipping is applied to a first output of the deblocking filter,

wherein a second clipping is applied to a second output of the SAO, and

wherein the clipped first output is used as an input of the SAO.

3. A non-transitory decoder-readable storage medium storing encoded data comprising information on instructions causing a decoding apparatus to perform a video decoding method comprising:

obtaining video information;

identifying whether an intra pulse code modulation (I_PCM) mode is applied to a current block in a current picture based on the video information;

generating a reconstructed picture including a reconstructed block of the current block based on the video information;

determining whether a deblocking filter is to be applied to the reconstructed block based on a result of the identification;

determining whether a sample adaptive offset (SAO) is to be applied to the reconstructed block based on the result of the identification; and

generating a modified reconstructed picture based on the reconstructed picture and results of the determinations,

wherein when the I_PCM mode is applied to the current block, the deblocking filter is not applied to the reconstructed block,

wherein when the I_PCM mode is applied to the current block, the SAO is not applied to the reconstructed block,

wherein when the I_PCM mode is not applied to the current block:

the modified reconstructed picture is generated based on the deblocking filter and the SAO on the reconstructed picture,

the SAO is used after the deblocking filter on the reconstructed picture,

a first clipping is applied to a first output of the deblocking filter,

a second clipping is applied to a second output of the SAO, and

the clipped first output is used as an input of the SAO.

4. The non-transitory decoder-readable storage medium of claim 3 , wherein the deblocking filter comprises determining a boundary strength (bS) of a block edge located within or on a boundary of the reconstructed block and determining whether to apply a deblocking filter to the block edge based on the bS, and

wherein a pixel value which is not subjected to the deblocking filter within the reconstructed block is determined, based on a determination that the deblocking filter is not applied to the reconstructed block, as a final pixel value.

5. The non-transitory decoder-readable storage medium of claim 4 , wherein, based on a determination that the deblocking filter is not applied to the reconstructed block, the deblocking filter is not applied to the block edge.

6. The non-transitory decoder-readable storage medium of claim 3 , wherein the SAO comprises determining whether a band offset type is to be applied, deriving a band group including multiple bands among 32 bands, applying an offset corresponding a band in the band group to a value of a pixel in the reconstructed block, and

wherein the value of the pixel in the reconstructed block is determined, based on a determination that the SAO is not applied to the reconstructed block, as a final pixel value.

7. The non-transitory decoder-readable storage medium of claim 3 , wherein the video information comprises PCM flag information to instruct whether the current block is coded in the I_PCM mode.

8. The non-transitory decoder-readable storage medium of claim 7 , wherein the video information further comprises PCM loop filter flag information to instruct whether an in-loop filter is disabled to a block coded in the I_PCM mode, and

Wherein, based on the PCM loop filter flag information including value 1 and the PCM flag information including value 1, both the deblocking filter and the SAO are not applied to the reconstructed block.