TECHNICAL FIELD

This patent document relates to video coding and decoding techniques, devices and systems.

BACKGROUND

In spite of the advances in video compression, digital video still accounts for the largest bandwidth use on the internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, it is expected that the bandwidth demand for digital video usage will continue to grow.

SUMMARY

The present document describes various embodiments and techniques for buffer management and block vector coding for intra block copy mode for decoding or encoding video or images.

In one example aspect, a method of video or image (visual data) processing is disclosed. The method includes determining a size of a buffer to store reference samples for prediction in an intra block copy mode; and performing a conversion between a current video block of visual media data and a bitstream representation of the current video block, using the reference samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.

In another example aspect, another method of visual data processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reconstructed samples for prediction in an intra block copy mode, wherein the buffer is used for storing the reconstructed samples before a loop filtering step; and performing the conversion using the reconstructed samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.

In yet another example aspect, another method of visual data processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reconstructed samples for prediction in an intra block copy mode, wherein the buffer is used for storing the reconstructed samples after a loop filtering step; and performing the conversion using the reconstructed samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in a same video region with the current video block without referring to a reference picture.

In yet another example aspect, another method of video processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reconstructed samples for prediction in an intra block copy mode, wherein the buffer is used for storing the reconstructed samples both before a loop filtering step and after the loop filtering step; and performing the conversion using the reconstructed samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.

In another example aspect, another method of video processing is disclosed. The method includes using a buffer to store reference samples for prediction in an intra block copy mode, wherein a first bit-depth of the buffer is different than a second bit-depth used to represent visual media data in the bitstream representation; and performing a conversion between a current video block of the visual media data and a bitstream representation of the current video block, using the reference samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.

In yet another example aspect, another method of video processing is disclosed. The method includes initializing a buffer to store reference samples for prediction in an intra block copy mode, wherein the buffer is initialized with a first value; and performing a conversion between a current video block of visual media data and a bitstream representation of the current video block using the reference samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.

In yet another example aspect, another method of video processing is disclosed. The method includes initializing a buffer to store reference samples for prediction in an intra block copy mode, wherein, based on availability of one or more video blocks in visual media data, the buffer is initialized with pixel values of the one or more video blocks in the visual media data; and performing a conversion between a current video block that does not belong to the one or more video blocks of the visual media data and a bitstream representation of the current video block, using the reference samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.

In yet another example aspect, another method of video processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reference samples for prediction in an intra block copy mode; performing the conversion using the reference samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture; and for a pixel spatially located at location (x0, y0) and having a block vector (BVx, BVy) included in the motion information, computing a corresponding reference in the buffer based on a reference location (P mod M, Q mod N) where “mod” is modulo operation and M and N are integers representing x and y dimensions of the buffer, wherein the reference location (P, Q) is determined using the block vector (BVx, BVy) and the location (x0, y0).

In yet another example aspect, another method of video processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reference samples for prediction in an intra block copy mode; performing the conversion using the reference samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture; and for a pixel spatially located at location (x0, y0) and having a block vector (BVx, BVy) included in the motion information, computing a corresponding reference in the buffer based on a reference location (P, Q), wherein the reference location (P, Q) is determined using the block vector (BVx, BVy) and the location (x0, y0).

In yet another example aspect, another method of video processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reference samples for prediction in an intra block copy mode, wherein pixel locations within the buffer are addressed using x and y numbers; and performing, based on the x and y numbers, the conversion using the reference samples stored in the buffer, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture.

In yet another example aspect, another method of video processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reference samples for prediction in an intra block copy mode, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture; for a pixel spatially located at location (x0, y0) of the current video block and having a block vector (BVx, BVy), computing a corresponding reference in the buffer at a reference location (P, Q), wherein the reference location (P, Q) is determined using the block vector (BVx, BVy) and the location (x0, y0); and upon determining that the reference location (P, Q) lies outside the buffer, re-computing the reference location using a sample in the buffer.

In yet another example aspect, another method of video processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reference samples for prediction in an intra block copy mode, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture; for a pixel spatially located at location (x0, y0) of the current video block relative to an upper-left position of a coding tree unit including the current video block and having a block vector (BVx, BVy), computing a corresponding reference in the buffer at a reference location (P, Q), wherein the reference location (P, Q) is determined using the block vector (BVx, BVy) and the location (x0, y0); and upon determining that the reference location (P, Q) lies outside the buffer, constraining at least a portion of the reference location to lie within a pre-defined range.

In yet another example aspect, another method of video processing is disclosed. The method includes determining, for a conversion between a current video block of visual media data and a bitstream representation of the current video block, a buffer that stores reference samples for prediction in an intra block copy mode, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture; for a pixel spatially located at location (x0, y0) of the current video block relative to an upper-left position of a coding tree unit including the current video block and having a block vector (BVx, BVy), computing a corresponding reference in the buffer at a reference location (P, Q), wherein the reference location (P, Q) is determined using the block vector (BVx, BVy) and the location (x0, y0); and upon determining that the block vector (BVx, BVy) lies outside the buffer, padding the block vector (BVx, BVy) according to a block vector of a sample value inside the buffer.

In yet another example aspect, another method of video processing is disclosed. The method includes resetting, during a conversion between a video and a bitstream representation of the video, a buffer that stores reference samples for prediction in an intra block copy mode at a video boundary; and performing the conversion using the reference samples stored in the buffer, wherein the conversion of a video block of the video is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the video block without referring to a reference picture.

In yet another example aspect, another method of video processing is disclosed. The method includes performing a conversion between a current video block and a bitstream representation of the current video block; and updating a buffer which is used to store reference samples for prediction in an intra-block copy mode, wherein the buffer is used for a conversion between a subsequent video block and a bitstream representation of the subsequent video block, wherein the conversion between the subsequent video block and a bitstream representation of the subsequent video block is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the subsequent video block without referring to a reference picture.

In yet another example aspect, another method of video processing is disclosed. The method includes determining, for a conversion between a current video block and a bitstream representation of the current video block, a buffer that is used to store reconstructed samples for prediction in an intra block copy mode, wherein the conversion is performed in the intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the current video block without referring to a reference picture; and applying a pre-processing operation to the reconstructed samples stored in the buffer, in response to determining that the reconstructed samples stored in the buffer are to be used for predicting sample values during the conversation.

In yet another example aspect, another method of video processing is disclosed. The method includes determining, selectively for a conversion between a current video block of a current virtual pipeline data unit (VPDU) of a video region and a bitstream representation of the current video block, whether to use K1 previously processed VPDUs from an even-numbered row of the video region and/or K2 previously processed VPDUs from an odd-numbered row of the video region; and performing the conversion, wherein the conversion excludes using remaining of the current VPDU, wherein the conversion is performed in an intra block copy mode which is based on motion information related to a reconstructed block located in same video region with the video block without referring to a reference picture.

In yet another example aspect, a video encoder or decoder apparatus comprising a processor configured to implement an above described method is disclosed.

In another example aspect, a computer readable program medium is disclosed. The medium stores code that embodies processor executable instructions for implementing one of the disclosed methods.

These, and other, aspects are described in greater details in the present document.

