Embodiments of the present disclosure relates generally to video coding techniques, and more particularly, to refinement in image or video coding.
In nowadays, digital video capabilities are being applied in various aspects of peoples' lives. Multiple types of video compression technologies, such as MPEG-2, MPEG-4, ITU-TH.263, ITU-TH.264/MPEG-4 Part 10 Advanced Video Coding (AVC), ITU-TH.265 high efficiency video coding (HEVC) standard, versatile video coding (VVC) standard, have been proposed for video encoding/decoding. However, coding efficiency of conventional video coding techniques is generally very low, which is undesirable.
Embodiments of the present disclosure provide a solution for video processing.
In a first aspect, a method for video processing is proposed. The method comprises: determining, during a conversion between a current video block of a video and a bitstream of the video, a refinement process applied to a current video unit associated with the current video block based on at least one of dimension information of the current video unit or coding tools applied to the current video unit; and performing the conversion based on the refinement process. The method in accordance with the first aspect of the present disclosure refines motion data of coding blocks before or after motion compensation. Additionally, the refinement process can be conducted flexibly based on the type of the coding technique and requirements on video processing. Compared with the conventional solution, the proposed method can advantageously improve the coding efficiency and enable a more precise prediction.
In a second aspect, an apparatus for video processing is proposed. The apparatus comprises a processor and a non-transitory memory coupled to the processor and having instructions stored thereon, wherein the instructions upon execution by the processor, cause the processor to: determine, during a conversion between a current video block of a video and a bitstream of the video, a refinement process applied to a current video unit associated with the current video block based on at least one of dimension information of the current video unit or coding tools applied to the current video unit; and generate the bitstream based on the determining.
In a third aspect, a non-transitory computer-readable storage medium is proposed. The non-transitory computer-readable storage medium storing instructions that cause a processor to perform a method in accordance with the first aspect of the present disclosure.
In a fourth aspect, a non-transitory computer-readable recording medium is proposed. The non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by an apparatus for video processing, wherein the method comprises: determining a refinement process applied to a current video unit associated with the current video block based on at least one of dimension information of the current video unit or coding tools applied to the current video unit; and generating the bitstream based on the second coding data.
In a fifth aspect, a method for storing a bitstream of a video is proposed. The method comprises: determining a refinement process applied to a current video unit associated with the current video block based on at least one of dimension information of the current video unit or coding tools applied to the current video unit; generating the bitstream based on the second coding data; and storing the bitstream in a non-transitory computer-readable recording medium.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
Through the following detailed description with reference to the accompanying drawings, the above and other objectives, features, and advantages of example embodiments of the present disclosure will become more apparent. In the example embodiments of the present disclosure, the same reference numerals usually refer to the same components.
Throughout the drawings, the same or similar reference numerals usually refer to the same or similar elements.
Principle of the present disclosure will now be described with reference to some embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.
In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.
References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an example embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and/or “including”, when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.
The video source 112 may include a source such as a video capture device. Examples of the video capture device include, but are not limited to, an interface to receive video data from a video content provider, a computer graphics system for generating video data, and/or a combination thereof.
The video data may comprise one or more pictures. The video encoder 114 encodes the video data from the video source 112 to generate a bitstream. The bitstream may include a sequence of bits that form a coded representation of the video data. The bitstream may include coded pictures and associated data. The coded picture is a coded representation of a picture. The associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. The I/O interface 116 may include a modulator/demodulator and/or a transmitter. The encoded video data may be transmitted directly to the destination device 120 via the I/O interface 116 through a network 130A. The encoded video data may also be stored onto a storage medium/server 130B for access by destination device 120.
The destination device 120 may include an I/O interface 126, a video decoder 124, and a display device 122. The I/O interface 126 may include a receiver and/or a modem. The I/O interface 126 may acquire encoded video data from the source device 110 or the storage medium/server 130B. The video decoder 124 may decode the encoded video data. The display device 122 may display the decoded video data to a user. The display device 122 may be integrated with the destination device 120, or may be external to the destination device 120 which is configured to interface with an external display device.
The video encoder 114 and the video decoder 124 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, Versatile Video Coding (VVC) standard and other current and/or future standards.
The video encoder 200 may be configured to implement any or all of the techniques of this disclosure. In the example of
In some embodiments, the video encoder 200 may include a partition unit 201, a predication unit 202 which may include a mode selection unit 203, a motion estimation unit 204, a motion compensation unit 205 and an intra prediction unit 206, a residual generation unit 207, a transform unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transform unit 211, a reconstruction unit 212, a buffer 213, and an entropy encoding unit 214.
In other examples, the video encoder 200 may include more, fewer, or different functional components. In an example, the predication unit 202 may include an intra block copy (IBC) unit. The IBC unit may perform predication in an IBC mode in which at least one reference picture is a picture where the current video block is located.
Furthermore, although some components, such as the motion estimation unit 204 and the motion compensation unit 205, may be integrated, but are represented in the example of
The partition unit 201 may partition a picture into one or more video blocks. The video encoder 200 and a video decoder 300 (which will be discussed in detail below) may support various video block sizes.
The mode selection unit 203 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra-coded or inter-coded block to the residual generation unit 207 to generate residual block data and to the reconstruction unit 212 to reconstruct the encoded block for use as a reference picture. In some examples, the mode selection unit 203 may select a combination of intra and inter predication (CIIP) mode in which the predication is based on an inter predication signal and an intra predication signal. The mode selection unit 203 may also select a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter-predication.
To perform inter prediction on a current video block, the motion estimation unit 204 may generate motion information for the current video block by comparing one or more reference frames from buffer 213 to the current video block. The motion compensation unit 205 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from the buffer 213 other than the picture associated with the current video block.
The motion estimation unit 204 and the motion compensation unit 205 may perform different operations for a current video block, for example, depending on whether the current video block is in an I-slice, a P-slice, or a B-slice. As used herein, an “I-slice” may refer to a portion of a picture composed of macroblocks, all of which are based upon macroblocks within the same picture. Further, as used herein, in some aspects, “P-slices” and “B-slices” may refer to portions of a picture composed of macroblocks that are not dependent on macroblocks in the same picture.
In some examples, the motion estimation unit 204 may perform uni-directional prediction for the current video block, and the motion estimation unit 204 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. The motion estimation unit 204 may then generate a reference index that indicates the reference picture in list 0 or list 1 that contains the reference video block and a motion vector that indicates a spatial displacement between the current video block and the reference video block. The motion estimation unit 204 may output the reference index, a prediction direction indicator, and the motion vector as the motion information of the current video block. The motion compensation unit 205 may generate the predicted video block of the current video block based on the reference video block indicated by the motion information of the current video block.
Alternatively, in other examples, the motion estimation unit 204 may perform bi-directional prediction for the current video block. The motion estimation unit 204 may search the reference pictures in list 0 for a reference video block for the current video block and may also search the reference pictures in list 1 for another reference video block for the current video block. The motion estimation unit 204 may then generate reference indexes that indicate the reference pictures in list 0 and list 1 containing the reference video blocks and motion vectors that indicate spatial displacements between the reference video blocks and the current video block. The motion estimation unit 204 may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. The motion compensation unit 205 may generate the predicted video block of the current video block based on the reference video blocks indicated by the motion information of the current video block.
In some examples, the motion estimation unit 204 may output a full set of motion information for decoding processing of a decoder. Alternatively, in some embodiments, the motion estimation unit 204 may signal the motion information of the current video block with reference to the motion information of another video block. For example, the motion estimation unit 204 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block.
In one example, the motion estimation unit 204 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 300 that the current video block has the same motion information as the another video block.
In another example, the motion estimation unit 204 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD). The motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 300 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.
As discussed above, the video encoder 200 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by the video encoder 200 include advanced motion vector predication (AMVP) and merge mode signaling.
The intra prediction unit 206 may perform intra prediction on the current video block. When performing intra prediction on the current video block, the intra prediction unit 206 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture. The prediction data for the current video block may include a predicted video block and various syntax elements.
The residual generation unit 207 may generate residual data for the current video block by subtracting (e.g., indicated by the minus sign) the predicted video block (s) of the current video block from the current video block. The residual data of the current video block may include residual video blocks that correspond to different sample components of the samples in the current video block.
In other examples, there may be no residual data for the current video block for the current video block, for example in a skip mode, and the residual generation unit 207 may not perform the subtracting operation.
The transform unit 208 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.
After the transform unit 208 generates a transform coefficient video block associated with the current video block, the quantization unit 209 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.
The inverse quantization unit 210 and the inverse transform unit 211 may apply inverse quantization and inverse transforms to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block. The reconstruction unit 212 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the predication unit 202 to produce a reconstructed video block associated with the current video block for storage in the buffer 213.
After the reconstruction unit 212 reconstructs the video block, a loop filtering operation may be performed to reduce video blocking artifacts in the video block.
The entropy encoding unit 214 may receive data from other functional components of the video encoder 200. When the data is received, the entropy encoding unit 214 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.
The video decoder 300 may be configured to perform any or all of the techniques of this disclosure. In the example of
In the example of
The entropy decoding unit 301 may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data). The entropy decoding unit 301 may decode the entropy coded video data, and from the entropy decoded video data, the motion compensation unit 302 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. The motion compensation unit 302 may, for example, determine such information by performing the AMVP and merge mode. AMVP is used, including derivation of several most probable candidates based on data from adjacent PBs and the reference picture. Motion information typically includes the horizontal and vertical motion vector displacement values, one or two reference picture indices, and, in the case of prediction regions in B slices, an identification of which reference picture list is associated with each index. As used herein, in some aspects, a “merge mode” may refer to deriving the motion information from spatially or temporally neighboring blocks.
The motion compensation unit 302 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.
The motion compensation unit 302 may use the interpolation filters as used by the video encoder 200 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. The motion compensation unit 302 may determine the interpolation filters used by the video encoder 200 according to the received syntax information and use the interpolation filters to produce predictive blocks.
The motion compensation unit 302 may use at least part of the syntax information to determine sizes of blocks used to encode frame(s) and/or slice(s) of the encoded video sequence, partition information that describes how each macroblock of a picture of the encoded video sequence is partitioned, modes indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter-encoded block, and other information to decode the encoded video sequence. As used herein, in some aspects, a “slice” may refer to a data structure that can be decoded independently from other slices of the same picture, in terms of entropy coding, signal prediction, and residual signal reconstruction. A slice can either be an entire picture or a region of a picture.
The intra prediction unit 303 may use intra prediction modes, which, for example, are received in the bitstream, to form a prediction block from spatially adjacent blocks. The inverse quantization unit 304 inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by the entropy decoding unit 301. The inverse transform unit 305 applies an inverse transform.
The reconstruction unit 306 may obtain the decoded blocks, e.g., by summing the residual blocks with the corresponding prediction blocks generated by the motion compensation unit 302 or intra-prediction unit 303. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts. The decoded video blocks are then stored in the buffer 307, which provides reference blocks for subsequent motion compensation/intra predication and also produces decoded video for presentation on a display device.
Some example embodiments of the present disclosure will be described in detailed hereinafter. It should be understood that section headings are used in the present document to facilitate ease of understanding and do not limit the embodiments disclosed in a section to only that section. Furthermore, while certain embodiments are described with reference to Versatile Video Coding or other specific video codecs, the disclosed techniques are applicable to other video coding technologies also. Furthermore, while some embodiments describe video coding steps in detail, it will be understood that corresponding steps decoding that undo the coding will be implemented by a decoder. Furthermore, the term video processing encompasses video coding or compression, video decoding or decompression and video transcoding in which video pixels are represented from one compressed format into another compressed format or at a different compressed bitrate.
This disclosure is related to video coding technologies. Specifically, it is about prediction mode refinement, motion information refinement, prediction samples refinement related techniques in video coding. It may be applied to the existing video coding standard like HEVC, VVC, and etc. It may be also applicable to future video coding standards or video codec.
Video coding standards have evolved primarily through the development of the well-known ITU-T and ISO/IEC standards. The ITU-T produced H.261 and H.263, ISO/IEC produced MPEG-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4 Advanced Video Coding (AVC) and H.265/HEVC standards (ITU-T and ISO/IEC, “High efficiency video coding”, Rec. ITU-T H.265| ISO/IEC 23008-2 (in force edition)). Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized. To explore the future video coding technologies beyond HEVC, the Joint Video Exploration Team (JVET) was founded by VCEG and MPEG jointly in 2015. The JVET meeting is concurrently held once every quarter, and the new video coding standard was officially named as Versatile Video Coding (VVC) in the April 2018 JVET meeting, and the first version of VVC test model (VTM) was released at that time. The VVC working draft and test model VTM are then updated after every meeting. The VVC project achieved technical completion (FDIS) at the July 2020 meeting.
2.1. Existing Coding Tools (Extracted from JVET-R2002)
In VVC, the merge candidate list is constructed by including the following five types of candidates in order:
The size of merge list is signalled in sequence parameter set header and the maximum allowed size of merge list is 6. For each CU code in merge mode, an index of best merge candidate is encoded using truncated unary binarization (TU). The first bin of the merge index is coded with context and bypass coding is used for other bins.
The derivation process of each category of merge candidates is provided in this session. As done in HEVC, VVC also supports parallel derivation of the merging candidate lists for all CUs within a certain size of area.
2.1.1.1. Spatial candidates derivation The derivation of spatial merge candidates in VVC is same to that in HEVC except the positions of first two merge candidates are swapped. A maximum of four merge candidates are selected among candidates located in the positions depicted in
In this step, only one candidate is added to the list. Particularly, in the derivation of this temporal merge candidate, a scaled motion vector is derived based on co-located CU belonging to the collocated referenncee picture. The reference picture list to be used for derivation of the co-located CU is explicitly signalled in the slice header. The scaled motion vector for temporal merge candidate is obtained as illustrated by the dotted line in
The position for the temporal candidate is selected between candidates C0 and C1, as depicted in
The history-based MVP (HMVP) merge candidates are added to merge list after the spatial MVP and TMVP. In this method, the motion information of a previously coded block is stored in a table and used as MVP for the current CU. The table with multiple HMVP candidates is maintained during the encoding/decoding process. The table is reset (emptied) when a new CTU row is encountered. Whenever there is a non-subblock inter-coded CU, the associated motion information is added to the last entry of the table as a new HMVP candidate.
The HMVP table size S is set to be 6, which indicates up to 6 History-based MVP (HMVP) candidates may be added to the table. When inserting a new motion candidate to the table, a constrained first-in-first-out (FIFO) rule is utilized wherein redundancy check is firstly applied to find whether there is an identical HMVP in the table. If found, the identical HMVP is removed from the table and all the HMVP candidates afterwards are moved forward, HMVP candidates could be used in the merge candidate list construction process. The latest several HMVP candidates in the table are checked in order and inserted to the candidate list after the TMVP candidate. Redundancy check is applied on the HMVP candidates to the spatial or temporal merge candidate.
To reduce the number of redundancy check operations, the following simplifications are introduced:
Pairwise average candidates are generated by averaging predefined pairs of candidates in the existing merge candidate list, and the predefined pairs are defined as {(0, 1), (0, 2), (1, 2), (0, 3), (1, 3), (2, 3)}, where the numbers denote the merge indices to the merge candidate list. The averaged motion vectors are calculated separately for each reference list. If both motion vectors are available in one list, these two motion vectors are averaged even when they point to different reference pictures; if only one motion vector is available, use the one directly; if no motion vector is available, keep this list invalid. When the merge list is not full after pair-wise average merge candidates are added, the zero MVPs are inserted in the end until the maximum merge candidate number is encountered.
Merge estimation region (MER) allows independent derivation of merge candidate list for the CUs in the same merge estimation region (MER). A candidate block that is within the same MER to the current CU is not included for the generation of the merge candidate list of the current CU. In addition, the updating process for the history-based motion vector predictor candidate list is updated only if (xCb+cbWidth)>>Log 2ParMrgLevel is greater than xCb>>Log 2ParMrgLevel and (yCb+cbHeight)>>Log 2ParMrgLevel is great than (yCb>>Log 2ParMrgLevel) and where (xCb, yCb) is the top-left luma sample position of the current CU in the picture and (cbWidth, cbHeight) is the CU size. The MER size is selected at encoder side and signalled as log 2_parallel_merge_level_minus2 in the sequence parameter set.
2.1.2. Merge Mode with MVD (MMVD)
In addition to merge mode, where the implicitly derived motion information is directly used for prediction samples generation of the current CU, the merge mode with motion vector differences (MMVD) is introduced in VVC. A MMVD flag is signalled right after sending a skip flag and merge flag to specify whether MMVD mode is used for a CU.
In MMVD, after a merge candidate is selected, it is further refined by the signalled MVDs information. The further information includes a merge candidate flag, an index to specify motion magnitude, and an index for indication of motion direction. In MMVD mode, one for the first two candidates in the merge list is selected to be used as MV basis. The merge candidate flag is signalled to specify which one is used.
Distance index specifies motion magnitude information and indicate the pre-defined offset from the starting point. As shown in
Direction index represents the direction of the MVD relative to the starting point. The direction index can represent of the four directions as shown in Table 2. It's noted that the meaning of MVD sign could be variant according to the information of starting MVs. When the starting MVs is an un-prediction MV or bi-prediction MVs with both lists point to the same side of the current picture (i.e. POCs of two references are both larger than the POC of the current picture, or are both smaller than the POC of the current picture), the sign in Table 2 specifies the sign of MV offset added to the starting MV. When the starting MVs is bi-prediction MVs with the two MVs point to the different sides of the current picture (i.e. the POC of one reference is larger than the POC of the current picture, and the POC of the other reference is smaller than the POC of the current picture), the sign in Table 2 specifies the sign of MV offset added to the list0 MV component of starting MV and the sign for the list1 MV has opposite value.
In order to increase the accuracy of the MVs of the merge mode, a bilateral-matching based decoder side motion vector refinement is applied in VVC. In bi-prediction operation, a refined MV is searched around the initial MVs in the reference picture list L0 and reference picture list L1. The BM method calculates the distortion between the two candidate blocks in the reference picture list L0 and list L1. As illustrated in
In VVC, the DMVR can be applied for the CUs which are coded with following modes and features:
The refined MV derived by DMVR process is used to generate the inter prediction samples and also used in temporal motion vector prediction for future pictures coding. While the original MV is used in deblocking process and also used in spatial motion vector prediction for future CU coding. The additional features of DMVR are mentioned in the following sub-clauses.
In DVMR, the search points are surrounding the initial MV and the MV offset obey the MV difference mirroring rule. In other words, any points that are checked by DMVR, denoted by candidate MV pair (MV0, MV1) obey the following two equations:
Where MV_offset represents the refinement offset between the initial MV and the refined MV in one of the reference pictures. The refinement search range is two integer luma samples from the initial MV. The searching includes the integer sample offset search stage and fractional sample refinement stage. 25 points full search is applied for integer sample offset searching. The SAD of the initial MV pair is first calculated. If the SAD of the initial MV pair is smaller than a threshold, the integer sample stage of DMVR is terminated. Otherwise SADs of the remaining 24 points are calculated and checked in raster scanning order. The point with the smallest SAD is selected as the output of integer sample offset searching stage. To reduce the penalty of the uncertainty of DMVR refinement, it is proposed to favor the original MV during the DMVR process. The SAD between the reference blocks referred by the initial MV candidates is decreased by ¼ of the SAD value.
The integer sample search is followed by fractional sample refinement. To save the calculational complexity, the fractional sample refinement is derived by using parametric error surface equation, instead of additional search with SAD comparison. The fractional sample refinement is conditionally invoked based on the output of the integer sample search stage. When the integer sample search stage is terminated with center having the smallest SAD in either the first iteration or the second iteration search, the fractional sample refinement is further applied.
In parametric error surface based sub-pixel offsets estimation, the center position cost and the costs at four neighboring positions from the center are used to fit a 2-D parabolic error surface equation of the following form
where (xmin, Ymin) corresponds to the fractional position with the least cost and C corresponds to the minimum cost value. By solving the above equations by using the cost value of the five search points, the (xmin, ymin) is computed as:
The value of xmin and ymin are automatically constrained to be between −8 and 8 since all cost values are positive and the smallest value is E(0,0). This corresponds to half peal offset with 1/16th-pel MV accuracy in VVC. The computed fractional (xmin, ymin) are added to the integer distance refinement MV to get the sub-pixel accurate refinement delta MV.
In VVC, the resolution of the MVs is 1/16 luma samples. The samples at the fractional position are interpolated using a 8-tap interpolation filter. In DMVR, the search points are surrounding the initial fractional-pel MV with integer sample offset, therefore the samples of those fractional position need to be interpolated for DMVR search process. To reduce the calculation complexity, the bi-linear interpolation filter is used to generate the fractional samples for the searching process in DMVR. Another important effect is that by using bi-linear filter is that with 2-sample search range, the DVMR does not access more reference samples compared to the normal motion compensation process. After the refined MV is attained with DMVR search process, the normal 8-tap interpolation filter is applied to generate the final prediction. In order to not access more reference samples to normal MC process, the samples, which is not needed for the interpolation process based on the original MV but is needed for the interpolation process based on the refined MV, will be padded from those available samples.
When the width and/or height of a CU are larger than 16 luma samples, it will be further split into subblocks with width and/or height equal to 16 luma samples. The maximum unit size for DMVR searching process is limit to 16×16.
2.1.4. Geometric partitioning mode (GPM) for Inter Prediction In VVC, a geometric partitioning mode is supported for inter prediction. The geometric partitioning mode is signalled using a CU-level flag as one kind of merge mode, with other merge modes including the regular merge mode, the MMVD mode, the CIIP mode and the subblock merge mode. In total 64 partitions are supported by geometric partitioning mode for each possible CU size w×h=2m×2n with m,n ∈{3 . . . 6} excluding 8×64 and 64×8.
When this mode is used, a CU is split into two parts by a geometrically located straight line (
If geometric partitioning mode is used for the current CU, then a geometric partition index indicating the partition mode of the geometric partition (angle and offset), and two merge indices (one for each partition) are further signalled. The number of maximum GPM candidate size is signalled explicitly in SPS and specifies syntax binarization for GPM merge indices. After predicting each of part of the geometric partition, the sample values along the geometric partition edge are adjusted using a blending processing with adaptive weights as in 3.4.2. This is the prediction signal for the whole CU, and transform and quantization process will be applied to the whole CU as in other prediction modes. Finally, the motion field of a CU predicted using the geometric partition modes is stored as in 2.1.4.3.
The uni-prediction candidate list is derived directly from the merge candidate list constructed according to the extended merge prediction process in 2.1.1. Denote n as the index of the uni-prediction motion in the geometric uni-prediction candidate list. The LX motion vector of the n-th extended merge candidate, with X equal to the parity of n, is used as the n-th uni-prediction motion vector for geometric partitioning mode. These motion vectors are marked with “x” in
After predicting each part of a geometric partition using its own motion, blending is applied to the two prediction signals to derive samples around geometric partition edge. The blending weight for each position of the CU are derived based on the distance between individual position and the partition edge. The distance for a position (x, y) to the partition edge are derived as:
where i,j are the indices for angle and offset of a geometric partition, which depend on the signaled geometric partition index. The sign of px,j and py,j depend on angle index i.
The weights for each part of a geometric partition are derived as following:
The partIdx depends on the angle index i. One example of weigh w0 is illustrated in
Mv1 from the first part of the geometric partition, Mv2 from the second part of the geometric partition and a combined My of Mv1 and Mv2 are stored in the motion filed of a geometric partitioning mode coded CU.
The stored motion vector type for each individual position in the motion filed are determined as:
where motionIdx is equal to d(4x+2, 4y+2). The partIdx depends on the angle index i. If sType is equal to 0 or 1, Mv0 or Mv1 are stored in the corresponding motion field, otherwise if sType is equal to 2, a combined My from Mv0 and Mv2 are stored. The combined Mv are generated using the following process:
In the contribution JVET-R0357, Geometric prediction mode with Motion Vector Difference (GMVD) is proposed. With GMVD, each geometric partition in GPM can decide to use GMVD or not. If GMVD is chosen for a geometric region, the MV of the region is calculated as a sum of the MV of a merge candidate and an MVD. All other processing is kept the same as in GPM.
With GMVD, an MVD is signaled as a pair of direction and distance, following the current design of MMVD. That is, there are eight candidate distances (¼-pel, ½-pel, 1-pel, 2-pel, 4-pel, 8-pel, 16-pel, 32-pel), and four candidate directions (toward-left, toward-right, toward-above, and toward-below). In addition, when pic_fpel_mmvd_enabled flag is equal to 1, the MVD in GMVD is also left shifted by 2 as in MMVD.
In VVC, when a CU is coded in merge mode, if the CU contains at least 64 luma samples (that is, CU width times CU height is equal to or larger than 64), and if both CU width and CU height are less than 128 luma samples, an additional flag is signalled to indicate if the combined inter/intra prediction (CIIP) mode is applied to the current CU. As its name indicates, the CIIP prediction combines an inter prediction signal with an intra prediction signal. The inter prediction signal in the CIIP mode Pinter is derived using the same inter prediction process applied to regular merge mode; and the intra prediction signal Pintra is derived following the regular intra prediction process with the planar mode. Then, the intra and inter prediction signals are combined using weighted averaging, where the weight value is calculated depending on the coding modes of the top and left neighbouring blocks (depicted in
The CIIP prediction is formed as follows:
The multi-hypothesis prediction previously proposed in JVET-M0425 is adopted in this contribution. Up to two additional predictors are signalled on top of inter AMVP mode, regular merge mode, and MMVD mode. The resulting overall prediction signal is accumulated iteratively with each additional prediction signal.
The weighting factor α is specified according to the following table:
For inter AMVP mode, MHP is only applied if non-equal weight in BCW is selected in bi-prediction mode.
Template matching (TM) is a decoder-side MV derivation method to refine the motion information of the current CU by finding the closest match between a template (i.e., top and/or left neighbouring blocks of the current CU) in the current picture and a block (i.e., same size to the template) in a reference picture. As illustrated in
In AMVP mode, an MVP candidate is determined based on template matching error to pick up the one which reaches the minimum difference between current block template and reference block template, and then TM performs only for this particular MVP candidate for MV refinement. TM refines this MVP candidate, starting from full-pel MVD precision (or 4-pel for 4-pel AMVR mode) within a [−8, +8]-pel search range by using iterative diamond search. The AMVP candidate may be further refined by using cross search with full-pel MVD precision (or 4-pel for 4-pel AMVR mode), followed sequentially by half-pel and quarter-pel ones depending on AMVR mode as specified in Table 3. This search process ensures that the MVP candidate still keeps the same MV precision as indicated by AMVR mode after TM process.
In merge mode, similar search method is applied to the merge candidate indicated by the merge index. As Table 3 shows, TM may perform all the way down to ⅛-pel MVD precision or skipping those beyond half-pel MVD precision, depending on whether the alternative interpolation filter (that is used when AMVR is of half-pel mode) is used according to merged motion information. Besides, when TM mode is enabled, template matching may work as an independent process or an extra MV refinement process between block-based and subblock-based bilateral matching (BM) methods, depending on whether BM can be enabled or not according to its enabling condition check.
In this contribution, a multi-pass decoder-side motion vector refinement is applied. In the first pass, bilateral matching (BM) is applied to the coding block. In the second pass, BM is applied to each 16×16 subblock within the coding block. In the third pass, MV in each 8×8 subblock is refined by applying bi-directional optical flow (BDOF). The refined MVs are stored for both spatial and temporal motion vector prediction.
In the first pass, a refined MV is derived by applying BM to a coding block. Similar to decoder-side motion vector refinement (DMVR), in bi-prediction operation, a refined MV is searched around the two initial MVs (MV0 and MV1) in the reference picture lists L0 and L1. The refined MVs (MV0_pass1 and MV1_pass1) are derived around the initiate MVs based on the minimum bilateral matching cost between the two reference blocks in L0 and L1.
BM performs local search to derive integer sample precision intDeltaMV. The local search applies a 3×3 square search pattern to loop through the search range [−sHor, sHor] in horizontal direction and [˜sVer, sVer] in vertical direction, wherein, the values of sHor and sVer are determined by the block dimension, and the maximum value of sHor and sVer is 8.
The bilateral matching cost is calculated as: bilCost=mvDistanceCost+sadCost. When the block size cbW*cbH is greater than 64, MRSAD cost function is applied to remove the DC effect of distortion between reference blocks. When the bilCost at the center point of the 3×3 search pattern has the minimum cost, the intDeltaMV local search is terminated. Otherwise, the current minimum cost search point becomes the new center point of the 3×3 search pattern and continue to search for the minimum cost, until it reaches the end of the search range.11
The existing fractional sample refinement is further applied to derive the final deltaMV. The refined MVs after the first pass is then derived as:
In the second pass, a refined MV is derived by applying BM to a 16×16 grid subblock. For each subblock, a refined MV is searched around the two MVs (MV0_pass1 and MV1_pass1), obtained on the first pass, in the reference picture list L0 and L1. The refined MVs (MV0_pass2(sbIdx2) and MV1_pass2(sbIdx2)) are derived based on the minimum bilateral matching cost between the two reference subblocks in L0 and L1.
For each subblock, BM performs full search to derive integer sample precision intDeltaMV. The full search has a search range [˜sHor, sHor] in horizontal direction and [−sVer, sVer] in vertical direction, wherein, the values of sHor and sVer are determined by the block dimension, and the maximum value of sHor and sVer is 8.
The bilateral matching cost is calculated by applying a cost factor to the SATD cost between two reference subblocks, as: bilCost=satdCost*costFactor. The search area (2*sHor+1)*(2*sVer+1) is divided up to 5 diamond shape search regions shown on
The existing VVC DMVR fractional sample refinement is further applied to derive the final deltaMV(sbIdx2). The refined MVs at second pass is then derived as:
In the third pass, a refined MV is derived by applying BDOF to an 8×8 grid subblock. For each 8×8 subblock, BDOF refinement is applied to derive scaled Vx and Vy without clipping starting from the refined MV of the parent subblock of the second pass. The derived bioMv(Vx, Vy) is rounded to 1/16sample precision and clipped between −32 and 32.
The refined MVs (MV0_pass3(sbIdx3) and MV1_pass3(sbIdx3)) at third pass are derived as:
The non-adjacent spatial merge candidates as in JVET-L0399 are inserted after the TMVP in the regular merge candidate list. The pattern of spatial merge candidates is shown in
The detailed embodiments below should be considered as examples to explain general concepts. These embodiments should not be interpreted in a narrow way. Furthermore, these embodiments can be combined in any manner.
The term ‘GPM’ may represent a coding method that split one block into two or more sub-regions wherein at least one sub-region is non-rectangular, or non-square, or it couldn't be generated by any of existing partitioning structure (e.g., QT/BT/TT) which splits one block into multiple rectangular sub-regions. In one example, for the GPM coded blocks, one or more weighting masks are derived for a coding block based on how the sub-regions are split, and the final prediction signal of the coding block is generated by a weighted-sum of two or more auxiliary prediction signals associated with the sub-regions.
The term ‘GPM’ may indicate the geometric merge mode (GEO), and/or geometric partition mode (GPM), and/or wedge prediction mode, and/or triangular prediction mode (TPM), and/or a GPM block with motion vector difference (GMVD), and/or a GPM block with motion refinement, and/or any variant based on GPM.
The term ‘block’ may represent a coding block (CB), a CU, a PU, a TU, a PB, a TB.
The phrase “normal/regular merge candidate” may represent the merge candidates generated by the extended merge prediction process (as illustrated in section 3.1). It may also represent any other advanced merge candidates except GEO merge candidates and subblock based merge candidates.
Note that a part/partition of a GPM/GMVD block means a part of a geometric partition in the CU, e.g., the two parts of a GPM block in
It should also be noticed that GPM/GMVD applied to other modes (e.g., AMVP mode) may also use the following methods wherein the motion for merge mode may be replaced by motion for AMVP mode. It is noticed that in the following descriptions, the term ‘GPM merge list’ is given as an example. However, the proposed solutions could also be extended to other GPM candidate list, such as GPM AMVP candidate list.
In the disclosure, a merge candidate is called to be “refined” if the motion information of the merge candidate is modified according to information signaled from the encoder or derived at the decoder. For example, a merge candidate may be refined by DVMR, FRUC, TM, MMVD, BDOF and so on. 1. In one example, during the GPM merge list construction process, the GPM motion information may be generated from a refined regular merge candidate.
The detailed embodiments below should be considered as examples to explain general concepts. These embodiments should not be interpreted in a narrow way. Furthermore, these embodiments can be combined in any manner.
The term ‘GPM’ may represent a coding method that split one block into two or more sub-regions wherein at least one sub-region is non-rectangular, or non-square, or it couldn't be generated by any of existing partitioning structure (e.g., QT/BT/TT) which splits one block into multiple rectangular sub-regions. In one example, for the GPM coded blocks, one or more weighting masks are derived for a coding block based on how the sub-regions are split, and the final prediction signal of the coding block is generated by a weighted-sum of two or more auxiliary prediction signals associated with the sub-regions.
The term ‘GPM’ may indicate the geometric merge mode (GEO), and/or geometric partition mode (GPM), and/or wedge prediction mode, and/or triangular prediction mode (TPM), and/or a GPM block with motion vector difference (GMVD), and/or a GPM block with motion refinement, and/or any variant based on GPM.
The term ‘block’ may represent a coding block (CB), a CU, a PU, a TU, a PB, a TB.
The phrase “normal/regular merge candidate” may represent the merge candidates generated by the extended merge prediction process (as illustrated in section 3.1). It may also represent any other advanced merge candidates except GEO merge candidates and subblock based merge candidates.
Note that a part/partition of a GPM/GMVD block means a part of a geometric partition in the CU, e.g., the two parts of a GPM block in
It should also be noticed that GPM/GMVD applied to other modes (e.g., AMVP mode) may also use the following methods wherein the motion for merge mode may be replaced by motion for AMVP mode.
1. In one example, motion-compensated prediction sample refinement process may be applied to a GPM block.
2. In one example, OBMC may be performed for all subblocks of a block coded with GPM.
3. In one example, when performing OBMC to a GPM block, the OBMC is applied based on the stored subblock (e.g., 4×4) based motion data of the current and neighboring GPM coded blocks.
4. In one example, whether to apply a feature/tool on top of GPM block may be dependent on the temporal layer identifier (e.g., layer ID) of the current picture among the group of pictures (GOP) structure.
5. In one example, in case motion vector difference is allowed to be used to a GPM block (named as GMVD), suppose M merge candidates are allowed for GPM without motion vector difference (named as GPM), and N merge candidates are allowed for GMVD, the following approaches are disclosed:
There are several flaws in the VVC v1 standard, which would be further improved for higher coding gain.
The detailed embodiments below should be considered as examples to explain general concepts. These embodiments should not be interpreted in a narrow way. Furthermore, these embodiments can be combined in any manner.
The terms ‘video unit’ or ‘coding unit’ or ‘block’ may represent a coding tree block (CTB), a coding tree unit (CTU), a coding block (CB), a CU, a PU, a TU, a PB, a TB.
A block may be rectangular or non-rectangular.
In the disclosure, the phrase “regular motion candidate” may represent a merge motion candidate in a regular/extended merge list indicated by a merge candidate index, or an AMVP motion vector, or an AMVP motion candidate in regular/extended AMVP list indicated by an AMVP candidate index.
In the disclosure, a motion candidate is called to be “refined” if the motion information of the candidate is modified according to information signaled from the encoder or derived at the decoder. For example, a motion vector may be refined by DMVR, FRUC, TM merge, TM AMVP, MMVD, GMVD, affine MMVD BDOF and so on.
In the disclosure, the phrase “coding data refinement” may represent a refinement process in order to refine the signalled/decoded/derived prediction modes, prediction directions, or signalled/decoded/derived motion information, prediction and/or reconstruction samples for a video unit. In one example, the refinement process may include motion candidate reordering.
1. In one example, the coding data Z of a video unit coded by a particular coding technique X may be further refined by another process Y.
2. For one video unit, multiple refinement processes may be applied.
3. In one example, the refinement process may be applied to one or more parts within a video unit.
4. In one example, whether or not apply the refinement process to a video unit and/or how to apply the refinement process may be controlled by one or multiple syntax elements (e.g., a flag).
5. In one example, whether to use refined coding data or original coding data (before being refined) for processing the current video unit and/or proceeding video units, may be dependent on what coding technique X is applied to the video unit.
6. In one example, whether to and/or how to apply a refinement process may depend on color format and/or color component.
7. In one example, whether to and/or how to apply a refinement process may depend on dimensions W×H of a block.
8. Whether to and/or how to apply a refinement process may depend on the coding tools applied to the current video unit.
9. In one example, how many blocks (or sub-blocks) or how many samples/pixels or which blocks/sub-blocks of a video unit would be processed through methods of refinement (e.g., via template matching, or bilateral matching) may be dependent on the dimensions W×H of the video unit and/or the coding tools applied to the video unit.
10. It is proposed that the refinement process (e.g., via template matching) may use the reconstruction samples in a different picture/samples generated from pictures excluding the current picture/samples generated from the current picture but not adjacent to current video unit.
11. In one example, bilateral matching may be dependent on multiple prediction blocks from the same reference picture list.
12. In one example, bilateral matching may be used to reorder the motion candidates.
13. In one example, how to apply bilateral matching, may be dependent on the prediction direction of the current block.
14. In one example, the refinement process may be dependent on the coding information (e.g., GPM coded information).
15. In one example, prediction samples of a neighbouring block instead of reconstruction samples of a neighbouring block may be used in a template matching method for an inter-coded block.
16. In one example, whether samples (such as prediction samples or reconstruction samples) of a neighbouring block can be used in a template matching method for an inter-coded block may depend on the coding information of the neighboring block.
17. For video units coded with the multiple-hypothesis prediction mode (wherein more than one prediction blocks for a given reference picture list is utilized), the refinement process may be applied. 1) In one example, the above-mentioned methods (e.g., bullet 1 to 16) may be applied.
According to the method 1700, multiple refinement processes may be applied to refine motion information of a video. Moreover, whether to apply the refinement process or how to apply the refinement process may depend on the type of coding technique for coding the motion data and requirements of video processing. Therefore, the prediction derived based on the proposed solution is more precise. Compared with the conventional solution, the method 1700 in accordance with some embodiments of the present disclosure can advantageously improve the coding performance and efficiency.
In some embodiments, determining the refinement process may comprise determining at least one of blocks or the sub-blocks in the current video unit to be applied with the refinement process, or samples or pixels in the current video unit to be applied with the refinement process. For example, based on the dimensions W×H of the video unit and/or the coding tools applied to the video unit, it is to be determined that how many blocks or sub-blocks or how many samples/pixels or which blocks/sub-blocks of a video unit are to be processed through methods of refinement. For example, the methods of refinement may refer to a template matching method or a bilateral matching method.
In some embodiments, if the current video unit satisfies a predefined dimension condition, surrounding blocks or surrounding sub-blocks within the current video unit are to be refined in the refinement process. In these embodiments, surrounding blocks or surrounding sub-blocks within the current video unit may be considered as blocks or subblocks located at boundaries of the current video unit.
In some embodiments, if the current video unit satisfies a predefined dimension condition, at least one block or at least one sub-block, which is not located at boundaries of the current video unit, is to be refined in the refinement process.
In some embodiments, if the current video unit satisfies a predefined dimension condition, blocks or sub-blocks located at at least one of a top first number of rows or a top second number of columns are to be refined in the refinement process, wherein at least one of the first and number is unequal to one. For example, for a current video unit with dimension satisfied certain conditions, the blocks/sub-blocks located at the top N rows and/or M columns may be refined, wherein at least one of N and M is unequal to 1.
In some embodiments, if a width of the current video unit is larger than or equal to a threshold width, and/or if a height of the current video unit is larger than or equal to a threshold height, at least one portion of blocks within the current video unit or at least one portion of sub-blocks within the current video unit are to be refined in the refinement process.
In some embodiments, if a width of the current video unit is less than or equal to a threshold width, and/or if a height of the current video unit is less than or equal to a threshold height, at least one portion of blocks within the current video unit or at least one portion of sub-blocks within the current video unit are to be refined in the refinement process.
For example, assuming that the current video unit has a dimension with W×H, at least part of blocks in the current video unit and/or at least part of blocks sub-blocks in the current video unit may perform refinement process if the dimensions W×H conform to one or more rules, such as if W>=T1 and/or H>=T2, if W<=T1 and/or H<=T2, if W>T1 and/or H>T2 or if W<T1 and/or H<T2.
In some embodiments, if a product of a width and a height of the current video unit is greater than or equal to a threshold product, at least one portion of blocks within the current video unit or at least one portion of sub-blocks within the current video unit are to be refined in the refinement process.
In some embodiments, if a product of a width and a height of the current video unit is less than a threshold product, at least one portion of blocks within the current video unit or at least one portion of sub-blocks within the current video unit are to be refined in the refinement process.
For example, assuming that the current video unit has a dimension with W×H, at least part of blocks in the current video unit and/or at least part of blocks sub-blocks in the current video unit may perform refinement process if the dimensions W×H conform to one or more rules, such as if W×H>=T, if W×H>T, if W×H<=T or if W×H<T.
In some embodiments, at least one of blocks, sub-blocks, samples or pixels of the current video unit to be applied with the refinement process is determined dependent on dimensions of the current video unit. That is, assuming that the current video unit has a dimension with W×H, which blocks (or sub-blocks) or samples/pixels of a video unit would be processed through methods of refinement may be dependent on the dimensions W×H of the video unit.
In some embodiments, positions of the blocks or the sub-blocks within the current video unit is determined dependent on dimensions of the current video unit. That is, assuming that the current video unit has a dimension with W×H, the positions of blocks (or sub-blocks) that are being processed may be determined based on the dimensions W×H of the video unit.
In some embodiments, whether the refinement process is applied to at least one of blocks, sub-blocks, samples or pixels within the current video unit is determined on-the-fly.
In some embodiments, the refinement process may use the reconstruction samples in a different picture, samples generated from pictures excluding the current picture and/or samples generated from the current picture but not adjacent to current video unit. For example, in these embodiments, the refinement process may refer to a template matching process.
In some embodiments, the template matching process is applied by using reconstruction or prediction samples in reference pictures other than reconstruction or prediction samples in a current picture associated with the current video unit. For example, in these embodiments, the template matching process may be applied to an INTER coded block or for motion refinement.
In some embodiments, the refinement process for an inter coded block or motion is applied without using reconstruction or prediction samples in a current picture associated with the current video unit. For example, in these embodiments, the refinement process may refer to a template matching process or a bilateral matching process.
In some embodiments, the refinement process for an inter coded block or motion is applied without using the intra coded reconstruction or prediction samples in a current picture associated with the current video unit. For example, in these embodiments, the refinement process may refer to a template matching process or a bilateral matching process.
In some embodiments, in a case where the refinement process refers to a bilateral matching process, the bilateral matching process may be applied dependent on one or more prediction blocks from a same reference picture list.
In some embodiments, the bilateral matching process is invoked by comparing a first number of prediction blocks in a second number of reference pictures from a same prediction direction. For example, the process may be invoked by comparing M (such as M>1) prediction blocks in N (such as N>1) reference pictures from the same prediction direction.
In some embodiments, the bilateral matching process may be used to refine/process the motion of an uni-prediction coded block.
In some embodiments, the bilateral matching process may be used to refine/process the LX (such as L0 or L1) motion of a bi-prediction coded block. In these embodiments, the bilateral matching process is applied by using a first prediction block from a first reference picture in a L0 reference list and second prediction block from a second reference picture in the L0 reference list. As another option, the bilateral matching process is applied by using a first prediction block from a first reference picture in a L1 reference list and second prediction block from a second reference picture in the L1 reference list.
In some embodiments, the current video unit may be coded with multiple-hypothesis prediction mode.
In some embodiments, the bilateral matching process may be used to reorder the motion candidates. In these embodiments, whether to and/or how to reorder the motion candidates with the bilateral matching process may depend on the coding mode. For example, the coding mode may refer to at least one of an affine merge, an affine advanced motion vector prediction (AMVP), a regular merge, a regular AMVP, a geometric partition mode (GPM), a triangular prediction mode (TPM), a merge mode with motion vector differences (MMVD), a template matching merge, a combined inter/intra prediction (CIIP), a geometric prediction mode with motion vector difference (GMVD) or an affine MMVD.
In some embodiments, the bilateral matching process may only be used to reorder the bi-directional motion candidates.
In some embodiments, for uni-directional motion candidates, the uni-directional motion candidates are arranged in a motion candidate list according to an initial order. In these embodiments, as an option, the uni-directional motion candidates may be put behind the bi-directional motion candidates. As another option, the uni-directional motion candidates may be put before the bi-directional motion candidates.
In some embodiments, for calculating the bilateral matching cost, the uni-directional motion candidates may be converted to the bi-directional motion candidates.
In some embodiments, the motion candidates may be reordered ascendingly according to cost values based on the bilateral matching process.
In some embodiments, the bilateral matching process is applied dependent on a prediction direction of a current block associated with the current video unit. That is, how to apply the bilateral matching process may be dependent on the prediction direction of the current block.
In some embodiments, whether the bilateral matching process is performed from motion-compensated prediction blocks in the same prediction direction, may be dependent on the prediction direction of the current block.
In these embodiments, if when an L0 predicted inter block is processed, the bilateral matching process is applied to the current block by using information of a first number of templates in a second number reference pictures in the L0 prediction direction. For example, when processing an L0 predicted INTER block, the bilateral matching process may be applied to this block by using information of M (such as M>1) templates in N (such as N>1) reference pictures in the L0 prediction direction.
As another option, if an L1 predicted inter block is processed, the bilateral matching process is applied to the current block by using information of a first number of templates in a second number reference pictures in the L1 prediction direction. For example, when processing an L1 predicted INTER block, the bilateral matching process may be applied to this block by using information of M (such as M>1) templates in N (such as N>1) reference pictures in the L1 prediction direction.
It is also possible that if a bi-directional predicted inter block is processed, the bilateral matching process is applied to the current block by using information of a first template in a L0 reference picture and a second template in a L1 reference picture. For example, when processing a bi-directional predicted INTER block, the bilateral matching process may be applied to this block by using information of a first template in a L0 reference picture and a second template in a L1 reference picture.
In some embodiments, the above-mentioned templates may be motion-compensated prediction blocks.
In some embodiments, the above-mentioned templated may be prediction/reconstruction samples neighboring to the motion-compensated prediction blocks.
In some embodiments, the conversion at 1704 may comprise decoding the target picture from the bitstream of the video
In some embodiments, the conversion at 1704 may comprise encoding the target picture into the bitstream of the video.
Implementations of the present disclosure can be described in view of the following clauses, the features of which can be combined in any reasonable manner.
Clause 1. A method for video processing, comprising: determining, during a conversion between a current video block of a video and a bitstream of the video, a refinement process applied to a current video unit associated with the current video block based on at least one of dimension information of the current video unit or coding tools applied to the current video unit; and performing the conversion based on the refinement process.
Clause 2. The method of clause 1, wherein determining the refinement process comprises determining at least one of the following: blocks or the sub-blocks in the current video unit to be applied with the refinement process, or samples or pixels in the current video unit to be applied with the refinement process.
Clause 3. The method of clause 1 or 2, wherein if the current video unit satisfies a predefined dimension condition, surrounding blocks or surrounding sub-blocks within the current video unit are to be refined in the refinement process.
Clause 4. The method of clause 3, wherein the surrounding blocks or the surrounding sub-blocks are located at boundaries of the current video unit.
Clause 5. The method of clause 1 or 2, wherein if the current video unit satisfies a predefined dimension condition, at least one block or at least one sub-block, which is not located at boundaries of the current video unit, is to be refined in the refinement process.
Clause 6. The method of clause 1 or 2, wherein if the current video unit satisfies a predefined dimension condition, blocks or sub-blocks located at at least one of a top first number of rows or a top second number of columns are to be refined in the refinement process, wherein at least one of the first and number is unequal to one.
Clause 7. The method of clause 1 or 2, wherein if a width of the current video unit is larger than or equal to a threshold width, and/or if a height of the current video unit is larger than or equal to a threshold height, at least one portion of blocks within the current video unit or at least one portion of sub-blocks within the current video unit are to be refined in the refinement process.
Clause 8. The method of clause 1 or 2, wherein if a width of the current video unit is less than or equal to a threshold width, and/or if a height of the current video unit is less than or equal to a threshold height, at least one portion of blocks within the current video unit or at least one portion of sub-blocks within the current video unit are to be refined in the refinement process.
Clause 9. The method of clause 1 or 2, wherein if a product of a width and a height of the current video unit is greater than or equal to a threshold product, at least one portion of blocks within the current video unit or at least one portion of sub-blocks within the current video unit are to be refined in the refinement process.
Clause 10. The method of clause 1 or 2, wherein if a product of a width and a height of the current video unit is greater than or equal to a threshold product, at least one portion of blocks within the current video unit or at least one portion of sub-blocks within the current video unit are to be refined in the refinement process.
Clause 11. The method of clause 1 or 2, wherein at least one of blocks, sub-blocks, samples or pixels of the current video unit to be applied with the refinement process is determined dependent on dimensions of the current video unit.
Clause 12. The method of clause 11, wherein positions of the blocks or the sub-blocks within the current video unit is determined dependent on dimensions of the current video unit.
Clause 13. The method of clause 1 or 2, wherein whether the refinement process is applied to at least one of blocks, sub-blocks, samples or pixels within the current video unit is determined on-the-fly.
Clause 14. The method of clause 1 or 2, wherein the refinement process is applied by using at least one of: reconstruction samples in a reference picture other than a current picture associated with the current video unit, samples generated from generated from pictures excluding the current picture, or samples generated from the current picture but not adjacent to the current video unit.
Clause 15. The method of clause 1 or 2, wherein a template matching process is applied by using reconstruction or prediction samples in reference pictures other than reconstruction or prediction samples in a current picture associated with the current video unit.
Clause 16. The method of clause 1 or 2, wherein the refinement process for an inter coded block or motion is applied without using reconstruction or prediction samples in a current picture associated with the current video unit.
Clause 17. The method of clause 1 or 2, wherein the refinement process for an inter coded block or motion is applied without using the intra coded reconstruction or prediction samples in a current picture associated with the current video unit.
Clause 18. The method of clause 1 or 2, wherein a bilateral matching process is applied dependent on one or more prediction blocks from a same reference picture list.
Clause 19. The method of clause 18, wherein the bilateral matching process is invoked by comparing a first number of prediction blocks in a second number of reference pictures from a same prediction direction.
Clause 20. The method of clause 18, wherein the bilateral matching process is used to refine or process a motion of a uni-prediction coded block.
Clause 21. The method of clause 18, wherein the bilateral matching process is used to refine or process a L0 or L1 motion of a bi-prediction coded block.
Clause 22. The method of clause 21, wherein the bilateral matching process is applied by using a first prediction block from a first reference picture in a L0 reference list and second prediction block from a second reference picture in the L0 reference list.
Clause 23. The method of clause 21, wherein the bilateral matching process is applied by using a first prediction block from a first reference picture in a L1 reference list and second prediction block from a second reference picture in the L1 reference list.
Clause 24. The method of any of clauses 1-23, wherein the current video unit is coded with a multiple-hypothesis prediction mode.
Clause 25. The method of clause 1 or 2, wherein a bilateral matching process is used to reorder motion candidates.
Clause 26. The method of clause 25, wherein whether to reorder the motion candidates with the bilateral matching process is determined dependent on a coding mode comprising at least one of the following: an affine merge, an affine advanced motion vector prediction (AMVP), a regular merge, a regular AMVP, a geometric partition mode (GPM), a triangular prediction mode (TPM), a merge mode with motion vector differences (MMVD), a template matching merge, a combined inter/intra prediction (CIIP), a geometric prediction mode with motion vector difference (GMVD) or an affine MMVD.
Clause 27. The method of clause 25, wherein the ordering of the motion candidates with the bilateral matching process is performed based on a coding mode comprising at least one of the following: an affine merge, an affine advanced motion vector prediction (AMVP), a regular merge, a regular AMVP, a geometric partition mode (GPM), a triangular prediction mode (TPM), a merge mode with motion vector differences (MMVD), a template matching merge, a combined inter/intra prediction (CIIP), a geometric prediction mode with motion vector difference (GMVD) or an affine MMVD.
Clause 28. The method of clause 25, wherein the bilateral matching process is used to reorder bi-directional motion candidates.
Clause 29. The method of clause 25, wherein if the bilateral matching process is used to reorder uni-directional motion candidates, the uni-directional motion candidates are arranged in a motion candidate list according to an initial order.
Clause 30. The method of clause 25, wherein if the bilateral matching process is used to reorder uni-directional motion candidates, the uni-directional motion candidates are put behind the bi-directional motion candidates.
Clause 31. The method of clause 25, wherein if the bilateral matching process is used to reorder uni-directional motion candidates, the uni-directional motion candidates are put before the bi-directional motion candidates.
Clause 32. The method of clause 29-31, wherein the uni-directional motion candidates are converted to bi-directional motion candidates for calculating a bilateral matching cost.
Clause 33. The method of clause 25, wherein the motion candidates are reordered ascendingly according to cost values based on the bilateral matching process.
Clause 34. The method of clause 1 or 2, wherein a bilateral matching process is applied dependent on a prediction direction of a current block associated with the current video unit.
Clause 35. The method of clause 34, wherein whether the bilateral matching process is performed from motion-compensated prediction blocks in a same prediction direction is determined dependent on the prediction direction of the current block.
Clause 36. The method of clause 34, wherein if when an L0 predicted inter block is processed, the bilateral matching process is applied to the current block by using information of a first number of templates in a second number reference pictures in the L0 prediction direction.
Clause 37. The method of clause 34, wherein if an L1 predicted inter block is processed, the bilateral matching process is applied to the current block by using information of a first number of templates in a second number reference pictures in the L1 prediction direction.
Clause 38. The method of clause 34, wherein if a bi-directional predicted inter block is processed, the bilateral matching process is applied to the current block by using information of a first template in a L0 reference picture and a second template in a L1 reference picture.
Clause 39. The method of any of clauses 36-38, wherein the templates are motion-compensated prediction blocks.
Clause 40. The method of any of clauses 36-38, wherein the templates are prediction or reconstruction samples neighboring to motion-compensated prediction blocks.
Clause 41. The method of any of clauses 1-40, wherein the refinement process comprises at least one of a template matching process or a bilateral matching process.
Clause 42. The method of any of clauses 1-41, wherein the conversion comprises decoding the current video block from the bitstream of the video.
Clause 43. The method of any of clauses 1-41, wherein the conversion comprises encoding the current video block into the bitstream of the video.
Clause 44. An apparatus for video processing, comprising a processor and a non-transitory memory coupled to the processor and having instructions stored thereon, wherein the instructions upon execution by the processor, cause the processor to: determine, during a conversion between a current video block of a video and a bitstream of the video, a refinement process applied to a current video unit associated with the current video block based on at least one of dimension information of the current video unit or coding tools applied to the current video unit; and perform the conversion based on the refinement process.
Clause 45. A non-transitory computer-readable storage medium storing instructions that cause a processor to perform a method in accordance with any of clauses 1 to 43.
Clause 46. Anon-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by an apparatus for video processing, wherein the method comprises: determining a refinement process applied to a current video unit associated with the current video block based on at least one of dimension information of the current video unit or coding tools applied to the current video unit; and generating the bitstream based on the determining.
Clause 47. A method for storing a bitstream of a video, comprising: determining a refinement process applied to a current video unit associated with the current video block based on at least one of dimension information of the current video unit or coding tools applied to the current video unit; generating the bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.
It would be appreciated that the computing device 1800 shown in
As shown in
In some embodiments, the computing device 1800 may be implemented as any user terminal or server terminal having the computing capability. The server terminal may be a server, a large-scale computing device or the like that is provided by a service provider. The user terminal may for example be any type of mobile terminal, fixed terminal, or portable terminal, including a mobile phone, station, unit, device, multimedia computer, multimedia tablet, Internet node, communicator, desktop computer, laptop computer, notebook computer, netbook computer, tablet computer, personal communication system (PCS) device, personal navigation device, personal digital assistant (PDA), audio/video player, digital camera/video camera, positioning device, television receiver, radio broadcast receiver, E-book device, gaming device, or any combination thereof, including the accessories and peripherals of these devices, or any combination thereof. It would be contemplated that the computing device 1800 can support any type of interface to a user (such as “wearable” circuitry and the like).
The processing unit 1810 may be a physical or virtual processor and can implement various processes based on programs stored in the memory 1820. In a multi-processor system, multiple processing units execute computer executable instructions in parallel so as to improve the parallel processing capability of the computing device 1800. The processing unit 1810 may also be referred to as a central processing unit (CPU), a microprocessor, a controller or a microcontroller.
The computing device 1800 typically includes various computer storage medium. Such medium can be any medium accessible by the computing device 1800, including, but not limited to, volatile and non-volatile medium, or detachable and non-detachable medium. The memory 1820 can be a volatile memory (for example, a register, cache, Random Access Memory (RAM)), a non-volatile memory (such as a Read-Only Memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), or a flash memory), or any combination thereof. The storage unit 1830 may be any detachable or non-detachable medium and may include a machine-readable medium such as a memory, flash memory drive, magnetic disk or another other media, which can be used for storing information and/or data and can be accessed in the computing device 1800.
The computing device 1800 may further include additional detachable/non-detachable, volatile/non-volatile memory medium. Although not shown in
The communication unit 1840 communicates with a further computing device via the communication medium. In addition, the functions of the components in the computing device 1800 can be implemented by a single computing cluster or multiple computing machines that can communicate via communication connections. Therefore, the computing device 1800 can operate in a networked environment using a logical connection with one or more other servers, networked personal computers (PCs) or further general network nodes.
The input device 1850 may be one or more of a variety of input devices, such as a mouse, keyboard, tracking ball, voice-input device, and the like. The output device 1860 may be one or more of a variety of output devices, such as a display, loudspeaker, printer, and the like. By means of the communication unit 1840, the computing device 1800 can further communicate with one or more external devices (not shown) such as the storage devices and display device, with one or more devices enabling the user to interact with the computing device 1800, or any devices (such as a network card, a modem and the like) enabling the computing device 1800 to communicate with one or more other computing devices, if required. Such communication can be performed via input/output (I/O) interfaces (not shown).
In some embodiments, instead of being integrated in a single device, some or all components of the computing device 1800 may also be arranged in cloud computing architecture. In the cloud computing architecture, the components may be provided remotely and work together to implement the functionalities described in the present disclosure. In some embodiments, cloud computing provides computing, software, data access and storage service, which will not require end users to be aware of the physical locations or configurations of the systems or hardware providing these services. In various embodiments, the cloud computing provides the services via a wide area network (such as Internet) using suitable protocols. For example, a cloud computing provider provides applications over the wide area network, which can be accessed through a web browser or any other computing components. The software or components of the cloud computing architecture and corresponding data may be stored on a server at a remote position. The computing resources in the cloud computing environment may be merged or distributed at locations in a remote data center. Cloud computing infrastructures may provide the services through a shared data center, though they behave as a single access point for the users. Therefore, the cloud computing architectures may be used to provide the components and functionalities described herein from a service provider at a remote location. Alternatively, they may be provided from a conventional server or installed directly or otherwise on a client device.
The computing device 1800 may be used to implement video encoding/decoding in embodiments of the present disclosure. The memory 1820 may include one or more video coding modules 1825 having one or more program instructions. These modules are accessible and executable by the processing unit 1810 to perform the functionalities of the various embodiments described herein.
In the example embodiments of performing video encoding, the input device 1850 may receive video data as an input 1870 to be encoded. The video data may be processed, for example, by the video coding module 1825, to generate an encoded bitstream. The encoded bitstream may be provided via the output device 1860 as an output 1880.
In the example embodiments of performing video decoding, the input device 1850 may receive an encoded bitstream as the input 1870. The encoded bitstream may be processed, for example, by the video coding module 1825, to generate decoded video data. The decoded video data may be provided via the output device 1860 as the output 1880.
While this disclosure has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present application as defined by the appended claims. Such variations are intended to be covered by the scope of this present application. As such, the foregoing description of embodiments of the present application is not intended to be limiting.
Number | Date | Country | Kind |
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PCT/CN2021/090315 | Apr 2021 | WO | international |
Filing Document | Filing Date | Country | Kind |
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PCT/CN2022/089288 | 4/26/2022 | WO |