Patent Application
20240107038
The present disclosure relates to video coding techniques, devices and systems.
Currently, efforts are underway to improve the performance of current video codec technologies to provide better compression ratios or provide video coding and decoding schemes that allow for lower complexity or parallelized implementations. Industry experts have recently proposed several new video coding tools and tests are currently underway for determining their effectivity.
Devices, systems and methods related to digital video coding, and specifically, to management of motion vectors are described. The described methods may be applied to existing video coding standards (e.g., High Efficiency Video Coding (HEVC) or Versatile Video Coding (VVC)) and future video coding standards or video codecs.
In one representative aspect, the disclosed technology may be used to provide a method for video processing. This method includes determining, for a conversion between a chroma block of a video and a bitstream representation of the video, applicability of a deblocking filter process to at least some samples at an edge of the chroma block based on a mode of joint coding of chroma residuals for the chroma block. The method also includes performing the conversion based on the determining.
In another representative aspect, the disclosed technology may be used to provide a method for video processing. This method includes determining, for a conversion between a current block of a video and a bitstream representation of the video, a chroma quantization parameter used in a deblocking filtering process applied to at least some samples at an edge of the current block based on information of a corresponding transform block of the current block. The method also includes performing the conversion based on the determining.
In another representative aspect, the disclosed technology may be used to provide a method for video processing. This method includes performing a conversion between a current block of a video and a bitstream representation of the video. During the conversion, a first chroma quantization parameter used in a deblocking filtering process applied to at least some samples along an edge of the current block is based on a second chroma quantization parameter used in a scaling process and a quantization parameter offset associated with a bit depth.
In another representative aspect, the disclosed technology may be used to provide a method for video processing. This method includes performing a conversion between a video comprising one or more coding units and a bitstream representation of the video. The bitstream representation conforms to a format rule that specifies that chroma quantization parameters are included in the bitstream representation at a coding unit level or a transform unit level according to the format rule.
In another representative aspect, the disclosed technology may be used to provide a method for video processing. This method includes performing a conversion between a block of a video and a bitstream representation of the video. The bitstream representation conforms to a format rule specifying that whether a joint coding of chroma residuals mode is applicable to the block is indicated at a coding unit level in the bitstream representation.
In another representative aspect, the disclosed technology may be used to provide a method for video processing. This method includes performing a conversion between a video unit and a coded representation of the video unit, wherein, during the conversion, a deblocking filter is used on boundaries of the video unit such that when a chroma quantization parameter (QP) table is used to derive parameters of the deblocking filter, processing by the chroma QP table is performed on individual chroma QP values.
In another representative aspect, the disclosed technology may be used to provide another method for video processing. This method includes performing a conversion between a video unit and a bitstream representation of the video unit, wherein, during the conversion, a deblocking filter is used on boundaries of the video unit such that chroma QP offsets are used in the deblocking filter, wherein the chroma QP offsets are at picture/slice/tile/brick/subpicture level.
In another representative aspect, the disclosed technology may be used to provide another method for video processing. This method includes performing a conversion between a video unit and a bitstream representation of the video unit, wherein, during the conversion, a deblocking filter is used on boundaries of the video unit such that chroma QP offsets are used in the deblocking filter, wherein information pertaining to a same luma coding unit is used in the deblocking filter and for deriving a chroma QP offset.
In another representative aspect, the disclosed technology may be used to provide another method for video processing. This method includes performing a conversion between a video unit and a bitstream representation of the video unit, wherein, during the conversion, a deblocking filter is used on boundaries of the video unit such that chroma QP offsets are used in the deblocking filter, wherein an indication of enabling usage of the chroma QP offsets is signaled in the bitstream representation.
In another representative aspect, the disclosed technology may be used to provide another method for video processing. This method includes performing a conversion between a video unit and a bitstream representation of the video unit, wherein, during the conversion, a deblocking filter is used on boundaries of the video unit such that chroma QP offsets are used in the deblocking filter, wherein the chroma QP offsets used in the deblocking filter are identical of whether joint coding of chroma residuals (JCCR) coding method is applied on a boundary of the video unit or a method different from the JCCR coding method is applied on the boundary of the video unit.
In another representative aspect, the disclosed technology may be used to provide another method for video processing. This method includes performing a conversion between a video unit and a bitstream representation of the video unit, wherein, during the conversion, a deblocking filter is used on boundaries of the video unit such that chroma QP offsets are used in the deblocking filter, wherein a boundary strength (BS) of the deblocking filter is calculated without comparing reference pictures and/or a number of motion vectors (MVs) associated with the video unit at a P side boundary with reference pictures of the video unit at a Q side boundary.
Further, in a representative aspect, an apparatus in a video system comprising a processor and a non-transitory memory with instructions thereon is disclosed. The instructions upon execution by the processor, cause the processor to implement any one or more of the disclosed methods.
Additionally, in a representative aspect, a video decoding apparatus comprising a processor configured to implement any one or more of the disclosed methods.
In another representative aspect, a video encoding apparatus comprising a processor configured to implement any one or more of the disclosed methods.
Also, a computer program product stored on a non-transitory computer readable media, the computer program product including program code for carrying out any one or more of the disclosed methods is disclosed.
The above and other aspects and features of the disclosed technology are described in greater detail in the drawings, the description and the claims.
Video coding standards have evolved primarily through the development of the well-known International Telecommunication Union—Telecommunication Standardization Sector (ITU-T) and International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) standards. The ITU-T produced H.261 and H.263, ISO/IEC produced Moving Picture Experts Group (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. 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, Joint Video Exploration Team (JVET) was founded by Video Coding Experts Group (VCEG) and MPEG jointly in 2015. Since then, many new methods have been adopted by JVET and put into the reference software named Joint Exploration Model (JEM). In April 2018, the Joint Video Expert Team (JVET) between VCEG (Q6/16) and ISO/IEC Joint Technical Committee (JTC1) SC29/WG11 (MPEG) was created to work on the VVC standard targeting at 50% bitrate reduction compared to HEVC.
A deblocking filter process is performed for each coding unit (CU) in the same order as the decoding process. First, vertical edges are filtered (horizontal filtering), then horizontal edges are filtered (vertical filtering). Filtering is applied to 8×8 block boundaries which are determined to be filtered, for both luma and chroma components. 4×4 block boundaries are not processed in order to reduce the complexity.
Three kinds of boundaries may be involved in the filtering process: CU boundary, transform unit (TU) boundary and PU boundary. CU boundaries, which are outer edges of CU, are always involved in the filtering since CU boundaries are always also TU boundary or PU boundary. When PU shape is 2N×N (N>4) and RQT depth is equal to 1, TU boundary at 8x8 block grid and PU boundary between each PU inside CU are involved in the filtering. One exception is that when the PU boundary is inside the TU, the boundary is not filtered.
Generally speaking, boundary strength (Bs) reflects how strong filtering is needed for the boundary. If Bs is large, strong filtering should be considered.
Let P and Q be defined as blocks which are involved in the filtering, where P represents the block located in left (vertical edge case) or above (horizontal edge case) side of the boundary and Q represents the block located in right (vertical edge case) or above (horizontal edge case) side of the boundary.
Bs is calculated on a 4×4 block basis, but it is re-mapped to an 8×8 grid. The maximum of the two values of Bs which correspond to 8 pixels consisting of a line in the 4×4 grid is selected as the Bs for boundaries in the 8×8 grid.
In order to reduce line buffer memory requirement, only for CTU boundary, information in every second block (4x4 grid) in left or above side is re-used as depicted in
2.1.2. β and tC decision
Threshold values β and tC which involving in filter on/off decision, strong and weak filter selection and weak filtering process are derived based on luma quantization parameter of P and Q blocks, QPP and QPQ, respectively. Q used to derive β and tC is calculated as follows.
Q=((QPP+QPQ+1)>>1).
A variable β is derived as shown in Table 1, based on Q. If Bs is greater than 1, the variable tC is specified as Table 1 with Clip3 (0, 55, Q+2) as input. Otherwise (BS is equal or less than 1), the variable tC is specified as Table 1 with 0 as input.
Filter on/off decision is done for four lines as a unit.
If dp0+dq0+dp3+dq3<β, filtering for the first four lines is turned on and strong/weak filter selection process is applied. Each variable is derived as follows.
If the condition is not met, no filtering is done for the first 4 lines. Additionally, if the condition is met, dE, dEp 1 and dEp2 are derived for weak filtering process. The variable dE is set equal to 1. If dp0+dp3<(β+(β>>1))>>3, the variable dEp 1 is set equal to 1. If dq0+dq3<(β+(β>>1))>>>3, the variable dEq1 is set equal to 1.
For the second four lines, decision is made in a same fashion with above.
After the first four lines are determined to filtering on in filter on/off decision, if following two conditions are met, strong filter is used for filtering of the first four lines. Otherwise, weak filter is used for filtering. Involving pixels are same with those used for filter on/off decision as depicted in
2*(dp0+dq0)<(β>>2),|p30−p00|+|q00−q30|<(β>>3) and |p00−q00|<(5*tC+1)>>1 1)
2*(dp3+dq3)<(β>>2), |p33−p03|+|q03−q33|<(β>>3) and |p03−q03|<(5*tC+1)>>1 2)
As a same fashion, if following two conditions are met, strong filter is used for filtering of the second 4 lines. Otherwise, weak filter is used for filtering.
2*(dp4+dq4)<(β>>2), |p34−p04|+|q04−q34|<(β>>3) and |p04−q04|<(5*tC+1)>>1 1)
2*(dp7+dq7)<(β>>2), |p37−p07|+|q07−q37|<(β>>3) and |p07−q07|<(5*tC+1)>>1 2)
For strong filtering, filtered pixel values are obtained by following equations. It is worth to note that three pixels are modified using four pixels as an input for each P and Q block, respectively.
p
0′=(p2+2*p1+2*p0+2*q0+q1+4)>>3
q
0′=(p1+2*p0+2*q0+2*q1+q2+4)>>3
p
1′=(p2+p1+p0+q0+2)>>2
q
1′=(p0+q0+q1+q2+2)>>2
p
2′=(2*p3+3*p2+p1+p0+q0+4)>>3
q
2′=(p0+q0+q1+3*q2+2*q3+4)>>3
Let's define Δ as follows.
Δ=(9*(q0−p0)−3*(q1−p1)+8)>>4
When abs(Δ) is less than tC*10,
Δ=Clip3(−tC,C,Δ)
p0′=Clip1Y(p0+Δ)
q0′=Clip1Y(q0−Δ)
If dEp1 is equal to 1,
Δp=Clip3(−(tC>>1),tC>>1,(((p2+p0+1)>>1)−p1+Δ)>>1)
p1′=Clip1Y(p1+Δp)
If dEq1 is equal to 1,
66
q=Clip3(−(tC>>1),tC>>1,(((q2+q0+1)>>1)−q1−Δ)>>1)
q1′=Clip1Y(q1+Δq)
It is worth to note that maximum two pixels are modified using three pixels as an input for each P and Q block, respectively.
Bs of chroma filtering is inherited from luma. If Bs>1 or if coded chroma coefficient existing case, chroma filtering is performed. No other filtering decision is there. And only one filter is applied for chroma. No filter selection process for chroma is used. The filtered sample values p0′ and q0′ are derived as follows.
Δ=Clip3(−tC,tC, ((((q0−p0)<<2)+p1−q1+4)>>3))
p0′=Clip1C(p0+Δ)
q0′=Clip1C(q0−Δ)
In the VVC test model (VTM)6, deblocking filtering process is mostly the same to those in HEVC. However, the following modifications are added.
In HEVC, the filter strength of the deblocking filter is controlled by the variables β and tC which are derived from the averaged quantization parameters qPL. In the VTM6, deblocking filter controls the strength of the deblocking filter by adding offset to qPL according to the luma level of the reconstructed samples if the SPS flag of this method is true. The reconstructed luma level LL is derived as follow:
LL=((p0,0+p0,3+q0,0+q0,3)>>1)/(1<<bitDepth) (3-1)
where, the sample values pi,k and qi,k with i=0 . . . 3 and k=0 and 3 can be derived. Then LL is used to decide the offset qpOffset based on the threshold signaled in SPS. After that, the qPL, which is derived as follows, is employed to derive the β and tC.
qPL=((QpQ+QpP+1)>>1)+qpOffset (3-2)
where QpQ and QpP denote the quantization parameters of the coding units containing the sample q0,0 and p0,0, respectively. In the current VVC, this method is only applied on the luma deblocking process.
HEVC uses an 8×8 deblocking grid for both luma and chroma. In VTM6, deblocking on a 4×4 grid for luma boundaries was introduced to handle blocking artifacts from rectangular transform shapes. Parallel friendly luma deblocking on a 4×4 grid is achieved by restricting the number of samples to be deblocked to 1 sample on each side of a vertical luma boundary where one side has a width of 4 or less or to 1 sample on each side of a horizontal luma boundary where one side has a height of 4 or less.
The detailed boundary strength derivation could be found in Table 2. The conditions in Table 2 are checked sequentially.
The proposal uses a bilinear filter when samples at either one side of a boundary belong to a large block. A sample belonging to a large block is defined as when the width>=32 for a vertical edge, and when height>=32 for a horizontal edge.
The bilinear filter is listed below.
Block boundary samples pi for i=0 to Sp−1 and qi for j=0 to Sq−1 (pi and qi follow the definitions in HEVC deblocking described above) are then replaced by linear interpolation as follows:
pi′=(fi*Middles,t+(64−fi)*Ps+32)>>6), clipped to pi±tcPDi
qj′=(gj*Middles,t+(64−gj)*Qs+32)>>6), clipped to qj±tcPDj
where tcPDi and tcPDj term is a position dependent clipping described in Section 2.2.5 and gj, fi, Middles,t, Ps and Qs are given below:
The deblocking decision process is described in this sub-section.
Wider-stronger luma filter is filters are used only if all of the Condition1, Condition2 and Condition 3 are TRUE.
The condition 1 is the “large block condition”. This condition detects whether the samples at P-side and Q-side belong to large blocks, which are represented by the variable bSidePisLargeBlk and bSideQisLargeBlk respectively. The bSidePisLargeBlk and bSideQisLargeBlk are defined as follows.
Based on bSidePisLargeBlk and bSideQisLargeBlk, the condition 1 is defined as follows. Condition1=(bSidePisLargeBlk∥bSidePisLargeBlk)?TRUE:FALSE
Next, if Condition 1 is true, the condition 2 will be further checked. First, the following variables are derived:
dp0, dp3, dq0, dq3 are first derived as in HEVC
if (p side is greater than or equal to 32)
dp0=(dp0+Abs(p5,0−2*p4,0+p3,0)+1)>>1
dp3=(dp3+Abs(p5,3−2*p4,3+p3,3)+1) >>1
if (q side is greater than or equal to 32)
dq0=(dq0+Abs(q5,0−2*q4,13+q3,13)+1)>>1
dq3=(dq3+Abs(q5,3−2*q4,3+q3,3)+1)>>1
dpq0, dpq3, dp, dq, d are then derived as in HEVC.
Then the condition 2 is defined as follows.
Condition2=(d<β)?TRUE:FALSE
Where d=dp0+dq0+dp3+dq3, as shown in section 2.1.4.
If Condition1 and Condition2 are valid it is checked if any of the blocks uses sub-blocks:
Finally, if both the Condition 1 and Condition 2 are valid, the proposed deblocking method will check the condition 3 (the large block Strong filter condition), which is defined as follows. In the Condition3 StrongFilterCondition, the following variables are derived:
As in HEVC derive, StrongFilterCondition=(dpq is less than (β>>2), sp3+sq3 is less than (3*β>>5), and Abs(p0−q0) is less than (5*tC+1)>>1)?TRUE:FALSE
The following strong deblocking filter for chroma is defined:
p
2′=(3*p3+2*p2+p1+p0+q0+4)>>3
p
1′=(2*p3+p2+2*p1+p0+q0+q1+4)>>3
p
0′=(p3+p2+p1+2*p0+q0+q1+q2+4)>>3
The proposed chroma filter performs deblocking on a 4×4 chroma sample grid.
The above chroma filter performs deblocking on a 8×8 chroma sample grid. The chroma strong filters are used on both sides of the block boundary. Here, the chroma filter is selected when both sides of the chroma edge are greater than or equal to 8 (in unit of chroma sample), and the following decision with three conditions are satisfied. The first one is for decision of boundary strength as well as large block. The second and third one are basically the same as for HEVC luma decision, which are on/off decision and strong filter decision, respectively.
The proposal also introduces a position dependent clipping tcPD which is applied to the output samples of the luma filtering process involving strong and long filters that are modifying 7, 5 and 3 samples at the boundary. Assuming quantization error distribution, it is proposed to increase clipping value for samples which are expected to have higher quantization noise, thus expected to have higher deviation of the reconstructed sample value from the true sample value.
For each P or Q boundary filtered with proposed asymmetrical filter, depending on the result of decision making process described in Section 2.2, position dependent threshold table is selected from Tc7 and Tc3 tables that are provided to decoder as a side information:
Tc7={6, 5, 4, 3, 2, 1, 1};
Tc3={ 6, 4, 2};
tcPD=(SP==3)?Tc3:Tc7;
tcQD=(SQ==3)?Tc3:Tc7;
For the P or Q boundaries being filtered with a short symmetrical filter, position dependent threshold of lower magnitude is applied:
Tc3={3, 2, 1};
Following defining the threshold, filtered p′i and q′i sample values are clipped according to tcP and tcQ clipping values:
p″
i=clip3(p′i+tcPi,p′i−tcPi,p′i);
q″
j=clip3(q′j+tcQi,q′j−tcQj,q′j);
where p′i and q′i are filtered sample values, p″i and q″j are output sample value after the clipping and tcPi tcPi are clipping thresholds that are derived from the VVC tc parameter and tcPD and tcQD. Term clip3 is a clipping function as it is specified in VVC.
To enable parallel friendly deblocking using both long filters and sub-block deblocking the long filters is restricted to modify at most 5 samples on a side that uses sub-block deblocking (AFFINE or ATMVP) as shown in the luma control for long filters. Additionally, the sub-block deblocking is adjusted such that that sub-block boundaries on an 8×8 grid that are close to a CU or an implicit TU boundary is restricted to modify at most two samples on each side. Following applies to sub-block boundaries that not are aligned with the CU boundary.
Where edge equal to 0 corresponds to CU boundary, edge equal to 2 or equal to orthogonalLength-2 corresponds to sub-block boundary 8 samples from a CU boundary etc. Where implicit TU is true if implicit split of TU is used.
Filtering of horizontal boundary is limiting Sp=3 for luma, Sp=1 and Sq=1 for chroma, when the horizontal boundary is aligned with the CTU boundary.
HEVC enables deblocking of a prediction unit boundary when the difference in at least one motion vector component between blocks on respective side of the boundary is equal to or larger than a threshold of 1 sample. In VTM6, a threshold of a half luma sample is introduced to also enable removal of blocking artifacts originating from boundaries between inter prediction units that have a small difference in motion vectors.
In VTM6, 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 as follows:
The CIIP prediction is formed as follows:
P
CIIP=((4−wt)*Pinter+wt*Pintra+2)>>2
In some embodiments, a chroma QP table is used. In some embodiments, a signalling mechanism is used for chroma QP tables, which enables that it is flexible to provide encoders the opportunity to optimize the table for standard definition resolution (SDR) and high definition resolution (HDR) content. It supports for signalling the tables separately for blue difference chroma (Cb) and red difference chroma (Cr) components. The proposed mechanism signals the chroma QP table as a piece-wise linear function.
As in HEVC, the residual of a block can be coded with transform skip mode. To avoid the redundancy of syntax coding, the transform skip flag is not signalled when the CU level MTS_CU_flag is not equal to zero. The block size limitation for transform skip is the same to that for MPEG Transport Stream (MTS) in JEM4, which indicate that transform skip is applicable for a CU when both block width and height are equal to or less than 32. Note that implicit MTS transform is set to discrete cosine transform (DCT)2 when Low Frequency Non-Separable Transform (LFNST) or Matrix-Based Intra Prediction (MIP) is activated for the current CU. Also the implicit MTS can be still enabled when MTS is enabled for inter coded blocks.
In addition, for transform skip block, minimum allowed Quantization Parameter (QP) is defined as 6*(internalBitDepth−inputBitDepth)+4.
In some embodiments, the chroma residuals are coded jointly. The usage (activation) of a joint chroma coding mode is indicated by a TU-level flag tu_joint_cbcr_residual_flag and the selected mode is implicitly indicated by the chroma CBFs. The flag tu_joint_cbcr_residual_flag is present if either or both chroma coding block flags (CBFs) for a TU are equal to 1. In the picture parameter set (PPS) and slice header, chroma QP offset values are signalled for the joint chroma residual coding mode to differentiate from the usual chroma QP offset values signalled for regular chroma residual coding mode. These chroma QP offset values are used to derive the chroma QP values for those blocks coded using the joint chroma residual coding mode. When a corresponding joint chroma coding mode (modes 2 in Table 3) is active in a TU, this chroma QP offset is added to the applied luma-derived chroma QP during quantization and decoding of that TU. For the other modes (modes 1 and 3 in Table 3Table 3 Reconstruction of chroma residuals. The value CSign is a sign value (+1 or −1), which is specified in the slice header, resJointC[ ][ ] is the transmitted residual.), the chroma QPs are derived in the same way as for conventional Cb or Cr blocks. The reconstruction process of the chroma residuals (resCb and resCr) from the transmitted transform blocks is depicted in Table 3. When this mode is activated, one single joint chroma residual block (resJointC[x][y] in Table 3) is signalled, and residual block for Cb (resCb) and residual block for Cr (resCr) are derived considering information such as tu_cbf cb, tu_cbf_cr, and CSign, which is a sign value specified in the slice header.
At the encoder side, the joint chroma components are derived as explained in the following. Depending on the mode (listed in the tables above), resJointC{1,2} are generated by the encoder as follows:
resJointC[x][y]=(resCb[x][y]+CSign*resCr[x][y])/2.
resJointC[x][y]=(4*resCb[x][y]+2*CSign*resCr[x][y])/5.
resJointC[x][y]=(4*resCr[x][y]+2*CSign*resCb[x][y])/5.
Different QPs are utilized are the above three modes. For mode 2, the QP offset signaled in PPS for JCCR coded block is applied, while for other two modes, it is not applied, instead, the QP offset signaled in PPS for non-JCCR coded block is applied.
The corresponding specification is as follows:
The variable QpY is derived as follows:
QpY=((qPY_PRED+CuQpDeltaVal+64+2*QpBdOffsetY)%(64+QpBdOffsetY))−QpBdOffsetY (8-933)
The luma quantization parameter Qp′Y is derived as follows:
Qp′Y=QpY+QpBdOffsetY (8-934)
When ChromaArrayType is not equal to 0 and treeType is equal to SINGLE_TREE or DUAL_TREE_CHROMA, the following applies:
qPiChroma=Clip3(−QpBdOffsetC,63,QpY) (8-935)
qPiCb=ChromaQpTable[0][qPiChroma] (8-936)
qPiCr=ChromaQpTable[1][qPiChroma] (8-937)
qPiCbCr=ChromaQpTable[2][qPiChroma] (8-938)
Qp′Cb=Clip3(−QpBdOffsetC,63,qPCb+pps_cb_qp_offset+slice_cb_qp_offset+CuQpOffsetCb)+QpBdOffsetC (8-939)
Qp′Cr=Clip3(−QpBdOffsetC,63,qPCr+pps_cr_qp_offset+slice_cr_qp_offset+CuQpOffsetCr)+QpBdOffsetC (8-940)
Qp′CbCr=Clip3(−QpBdOffsetC,63,qPCbCr+pps_cbcr_qp_offset+slice_cbcr_qp_offset+CuQpOffsetCbCr)+QpBdOffsetC (8-941)
Inputs to this process are:
Output of this process is the (nTbW)×(nTbH) array d of scaled transform coefficients with elements d[x][y]. The quantization parameter qP is derived as follows:
If cIdx is equal to 0 and transform_skip_flag[xTbY][yTbY] is equal to 0, the following applies:
qP=Qp′Y (8-950)
qP=Max(QpPrimeTsMin,Qp′Y) (8-951)
qP=QP′CbCr (8-952)
Otherwise, if cIdx is equal to 1, the following applies:
qP=Qp′Cb (8-953)
qP=Qp′Cr (8-954)
where
(x, y) is chroma component i location being refined
(xc, yc) is the luma location based on (x, y)
Si is filter support in luma for chroma component i
ci (x0, y0) represents the filter coefficients
Key features characteristics of the CC-ALF process include:
DMVR and BIO do not involve the original signal during refining the motion vectors, which may result in coding blocks with inaccurate motion information. Also, Decoder-Side Motion Vector Refinement (DMVR) and Bi-directional Optical Flow (BDOF) sometimes employ the fractional motion vectors after the motion refinements while screen videos usually have integer motion vectors, which makes the current motion information more inaccurate and make the coding performance worse.
1. The interaction between chroma QP table and chroma deblocking may have problems, e.g., chroma QP table should be applied to individual QP but not weighted sum of QPs.
2. The logic of luma deblocking filtering process is complicated for hardware design.
3. The logic of boundary strength derivation is too complicated for both software and hardware design.
4. In the BS decision process, JCCR is treated separately from those blocks coded without JCCT applied. However, JCCR is only a special way to code the residual. Therefore, such design may bring additional complexity without no clear benefits.
5. In chroma edge decision, QpQ and QpP are set equal to the QpY values of the coding units which include the coding blocks containing the sample q0,0 and p0,0, respectively. However, in the quantization/de-quantization process, the QP for a chroma sample is derived from the QP of luma block covering the corresponding luma sample of the center position of current chroma CU. When dual tree is enabled, the different locations of luma blocks may result in different QPs. Therefore, in the chroma deblocking process, wrong QPs may be used for filter decision. Such a misalignment may result in visual artifacts. An example is shown in
6. A different picture level QP offset (i.e., pps_joint_cbcr_qp_offset) is applied to JCCR coded blocks which is different from the picture level offsets for Cb/Cr (e.g., pps_cb_qp_offset and pps_cr_qp_offset) applied to non-JCCR coded blocks. However, in the chroma deblocking filter decision process, only those offsets for non-JCCR coded blocks are utilized. The missing of consideration of coded modes may result in wrong filter decision.
7. The transform skip (TS) and non-TS coded blocks employ different QPs in the de-quantization process, which may be also considered in the deblocking process.
8. Different QPs are used in the scaling process (quantization/dequantization) for JCCR coded blocks with different modes. Such a design is not consistent.
9. The chroma deblocking for Cb/Cr could be unified for parallel design.
The detailed embodiments described below should be considered as examples to explain general concepts. These embodiments should not be interpreted narrowly way. Furthermore, these embodiments can be combined in any manner.
The methods described below may be also applicable to other decoder motion information derivation technologies in addition to the DMVR and BIO mentioned below.
In the following examples, MVM[i].x and MVM[i].y denote the horizontal and vertical component of the motion vector in reference picture list i (i being 0 or 1) of the block at M (M being P or Q) side. Abs denotes the operation to get the absolute value of an input, and “&&” and “∥” denotes the logical operation AND and OR. Referring to
1. When chroma QP table is used to derive parameters to control chroma deblocking (e.g., in the decision process for chroma block edges), chroma QP offsets may be applied after applying chroma QP table.
2. QP clipping may be not applied to the input of a chroma QP table.
3. It is proposed that deblocking process for chroma components may be based on the mapped chroma QP (by the chroma QP table) on each side.
4. It is proposed that deblocking process for chroma components may be based on the QP applied to quantization/dequantization for the chroma block.
5. It is proposed to consider the picture/slice/tile/brick/subpicture level quantization parameter offsets used for different coding methods in the deblocking filter decision process.
6. The chroma filtering process (e.g., the chroma edge decision process) which requires to access the decoded information of a luma block may utilize the information associated with the same luma coding block that is used to derive the chroma QP in the dequantization/quantization process.
7. The chroma filtering process (e.g., the chroma edge decision process) may depend on the quantization parameter applied to the scaling process of the chroma block (e.g., quantization/dequantization).
8. Whether to invoke above bullets may depend on the sample to be filtered is in the block at P or Q side.
9. Chroma QP used in deblocking may depend on information of the corresponding transform block.
10. Signaling of chroma QPs may be in coding unit.
11. Whether a block is of joint_cb_cr mode may be indicated at coding unit level.
12. Chroma QP used in deblocking may depend on chroma QP used in scaling process minus QP offset due to bit depth.
13. In one example, Chroma QP used in deblocking at Q-side is set to the Cr chroma QP used in scaling process, i.e., Qp′Cr, minus QpBdOffsetC when TuCResMode[xTb][yTb] is equal to 2 where (xTb, yTb) denotes the transform blocking containing the last sample at Q-side, i.e., q0,0.
14. It is proposed to signal the indication of enabling block-level chroma QP offset (e.g., slice_cu_chroma_qp_offset_enabled_flag) at the slice/tile/brick/subpicture level.
15. Same QP derivation method is used in the scaling process (quantization/dequantization) for JCCR coded blocks with different modes.
16. Deblocking for all color components excepts for the first color component may follow the deblocking process for the first color component.
17. How to calculate gradient used in the deblocking filter process may depend on the coded mode information and/or quantization parameters.
18. It is proposed to treat JCCR coded blocks as those non-JCCR coded blocks in the boundary strength decision process.
19. It is proposed to derive the boundary strength (BS) without comparing the reference pictures and/or number of MVs associated with the block at P side with the reference pictures of the block at Q side.
20. The deblocking may use different QPs for TS coded blocks and non-TS coded blocks.
21. The luma filtering process (e.g., the luma edge decision process) may depend on the quantization parameter applied to the scaling process of the luma block.
22. It is proposed to use an identical gradient computation for large block boundaries and smaller block boundaries.
23. The values for specific positions of quantization matrices may be set to constant.
24. A constrain may be set that the average/weighted average of some positions of quantization matrices may be a constant.
25. One or multiple indications may be signaled in the picture header to inform the scaling matrix to be selected in the picture associated with the picture header.
26. CCALF may be applied before some loop filtering process at the decoder
27. Signaling and/or selection of chroma QP offset lists may be dependent on the coded prediction modes/picture types/slice or tile or brick types.
28. How to select the QPs (e.g., using corresponding luma or chroma dequantized QP) utilized in the deblocking filter process may be dependent on the position of samples relative to the CTU/CTB/VPDU boundaries.
29. How to select the QPs (e.g., using corresponding luma or chroma dequantized QP) utilized in the deblocking filter process may depend on color formats (such as RGB and YCbCr) and/or color sampling format (such as 4:2:0, 4:2:2 and 4:4:4), and/or color down-sampling positions or phases).
30. For edges at CTU boundary, the deblocking may be based on luma QP of the corresponding blocks.
31. For horizontal edges at CTU boundary, the deblocking may be based on a function of chroma QPs at P-side.
32. It may be constrained that QP for chroma component may be the same for a chroma row segment with length 4*m starting from (4*m*x, 2y) relative to top-left of the picture, where x and y are non-negative integers; and m is a positive integer.
33. It may be constrained that QP for chroma component may be the same for a chroma column segment with length 4*n starting from (2*x, 4*n*y) relative to top-left of the picture, where x and y are non-negative integers; and n is a positive integer.
34. A first syntax element controlling the usage of coding tool X may be signalled in a first video unit (such as picture header), depending on a second syntax element signalled in a second video unit (such as SPS or PPS, or VPS).
35. Deblocking filter decision processes for two chroma blocks may be unified to be only invoked once and the decision is applied to two chroma blocks.
36. The above proposed methods may be applied under certain conditions.
The newly added texts are shown in underlined bold italicized font. The deleted texts are marked by [[]].
cQpPicOffset=cIdx==1?pps_cb_qp_offset:pps_cr_qp_offset (8-1065)
. . .
The variables QpQ and QpP are set equal to the QpY values of the coding units which include the coding blocks containing the sample q0,0 and p0,0, respectively.
The variable QpC is derived as follows:
[[qPi=Clip3(0,63,((QpQ+QpP+1)>>1)+cQpPicOffset) (8-1132)
QpC=ChromaQpTable[cIdx−1][qPi] (8-1133)]]
qPi=(QpQ+QpP+1)>>1 (8-1132)
QpC=ChromaQpTable[cIdx−1][qPi]+cQpPicOffset (8-1133)
NOTE—The variable cQpPicOffset provides an adjustment for the value of pps_cb_qp_offset or pps_cr_qp_offset, according to whether the filtered chroma component is the Cb or Cr component. However, to avoid the need to vary the amount of the adjustment within the picture, the filtering process does not include an adjustment for the value of slice_cb_qp_offset or slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is equal to 1) for the value of CuQpOffsetCb, CuQpOffsetCr, or CuQpOffsetCbCr.
The value of the variable β′ is determined as specified in Table 8-18 based on the quantization parameter Q derived as follows:
Q=Clip3(0,63,QpC+(slice_beta_offset_div2<<1)) (8-1134)
where slice_beta_offset_div2 is the value of the syntax element slice_beta_offset_div2 for the slice that contains sample q0,0.
The variable is derived as follows:
β=β′*(1<<(BitDepthC−8)) (8-1135)
The value of the variable tC′ is determined as specified in Table 8-18 based on the chroma quantization parameter Q derived as follows:
Q=Clip3(0,65,QpC+2*(bS−1)+(slice_tc_offset_div2<<1)) (8-1136)
where slice_tc_offset_div2 is the value of the syntax element slice_tc_offset_div2 for the slice that contains sample q0,0.
The variable tC is derived as follows:
t
C=(BitDepthC<10)?(tC′+2)>>(10−BitDepthC):tC* (1<<(BitDepthC−8)) (8-1137)
Inputs to this process are:
Output of this process is a two-dimensional (nCbW)×(nCbH) array bS specifying the boundary filtering strength.
. . .
For xDi with i=0 . . . xN and yDj with j=0 . . . yN, the following applies:
Inputs to this process are:
Output of this process is a two-dimensional (nCbW)×(nCbH) array bS specifying the boundary filtering strength.
. . .
For xDi with i=0 . . . xN and yDj with j=0 . . . yN, the following applies:
Inputs to this process are:
Outputs of this process are:
. . .
The following ordered steps apply:
. . .
1. When sidePisLargeBlk or sideQisLargeBlk is greater than 0, the following applies:
dp0L=(dp0+Abs(p5,0−2*p4,0+p3,0)+1)>>1 (8-1087)
dp3L=(dp3+Abs(p5,3−2*p4,3+p3,3)+1)>>1 (8-1088)
dp0L=dp0 (8-1089)
dp3L=dp3 (8-1090)
[[maxFilterLengthP=3 (8-1091)]]
dq0L=(dq0+Abs(q5,0−2*q4,0+q3,0)+1)>>1 (8-1092)
dq3L=(dq3+Abs(q5,3−2*q4,3+q3,3)+1)>>1 (8-1093)
dq0L=dq0 (8-1094)
dq3L=dq3 (8-1095)
2. The variables dE, dEp and dEq are derived as follows:
This process is only invoked when ChromaArrayType is not equal to 0.
Inputs to this process are:
Outputs of this process are
The variable maxK is derived as follows:
maxK=(SubHeightC==1)?3:1 (8-1124)
maxK=(SubWidthC==1)?3:1 (8-1125)
The values pi and qi with i=0 . . . maxFilterLengthCbCr and k=0 . . . maxK are derived as follows:
q
i,k=recPicture[xCb+xB1+i][yCb+yB1+k] (8-1126)
p
i,k=recPicture[xCb+xB1−−i−1][yCb+yB1+k] (8-1127)
subSampleC=SubHeightC (8-1128)
q
i,k=recPicture[xCb+xB1+k][yCb+yB1+i] (8-1129)
p
i,k=recPicture[xCb+xB1+k][yCb+yB1−i−1] (8-1130)
subSampleC=SubWidthC (8-1131)
The value of the variable β is determined as specified in Table t-18 based on the quantization parameter Q derived as follows:
Q=Clip3(0, 63,QpC+(slice_beta_offset_div2<<1)) (8-1134)
where slice_beta_offset_div2 is the value of the syntax element slice_beta_offset_div2 for the slice that contains sample q0,0.
The variable β is derived as follows:
β=β′*(1<<(BitDepthC−8)) (8-1135)
The value of the variable tC′ is determined as specified in Table 8-18 based on the chroma quantization parameter Q derived as follows:
Q=Clip3(0,65,QpC+2*(bS−1)+(slice_tc_offset_div2<<1)) (8-1136)
where slice_tc_offset_div2 is the value of the syntax element slice_tc_offset_div2 for the slice that contains sample q0,0.
The variable tC is derived as follows:
t
C=(BitDepthC<10)?(tC′+2)>>(10−BitDepthC):tC′*(1<<(BitDepthC−8)) (8-1137)
When maxFilterLengthCbCr is equal to 1 and bS is not equal to 2, maxFilterLengthCbCr is set equal to 0.
This process is only invoked when ChromaArrayType is not equal to 0.
Inputs to this process are:
Outputs of this process are
The variable maxK is derived as follows:
maxK=(SubHeightC==1)?3:1 (8-1124)
maxK=(SubWidthC==1)?3:1 (8-1125)
The values pi and qi with i=0 . . . maxFilterLengthCbCr and k=0 . . . maxK are derived as follows:
q
i,k=recPicture[xCb+xB1+i][yCb+yB1+k] (8-1126)
p
i,k=recPicture[xCb+xB1−i−1][yCb+yB1+k] (8-1127)
subSampleC=SubHeightC (8-1128)
q
i,k=recPicture[xCb+xB1+k][yCb+yB1+i] (8-1129)
p
i,k=recPicture[xCb+xB1+k][yCb+yB1−i−1] (8-1130)
subSampleC=SubWidthC (8-1131)
The variables QpQ and QpP are set equal to the QpY values of the coding units which include the coding blocks containing the sample q0,0 and p0,0 respectively.
The variable QpC is derived as follows:
[[qPi=Clip3(0,63,((QpQ+QpP+1)>>1)+cQpPicOffset) (8-1132)]]
QpC=ChromaQpTable[cIdx−1][qPi] (8-1133)
NOTE—The variable cQpPicOffset provides an adjustment for the value of pps_cb_qp_offset or pps_cr_qp_offset, according to whether the filtered chroma component is the Cb or Cr component. However, to avoid the need to vary the amount of the adjustment within the picture, the filtering process does not include an adjustment for the value of slice_cb_qp_offset or slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is equal to 1) for the value of CuQpOffsetCb, CuQpOffsetCr, or CuQpOffsetCbCr.
This process is only invoked when ChromaArrayType is not equal to 0.
Inputs to this process are:
Outputs of this process are
The variable maxK is derived as follows:
maxK=(SubHeightC==1)?3:1 (8-1124)
maxK=(SubWidthC==1)?3:1 (8-1125)
The values pi and qi with i=0 . . . maxFilterLengthCbCr and k=0 . . . maxK are derived as follows:
q
i,k=recPicture[xCb+xB1+i][yCb+yB1+k] (8-1126)
p
i,k=recPicture[xCb+xB1−i−1][yCb+yB1+k] (8-1127)
subSampleC=SubHeightC (8-1128)
q
i,k=recPicture[xCb+xB1+k][yCb+yB1+i] (8-1129)
p
i,k=recPicture[xCb+xB1+k][yCb+yB1−i−1] (8-1130)
subSampleC=SubWidthC (8-1131)
[[The variables QpQ and QpP are set equal to the QpY values of the coding units which include the coding blocks containing the sample q0,0 and p0,0, respectively.]]
The variable QpC is derived as follows:
qPi=Clip3(0,63,((QpQ+QpP+1)>>1)+cQpPicOffset) (8-1132)
QpC=ChromaQpTable[cIdx−1][qPi] (8-1133)
NOTE—The variable cQpPicOffset provides an adjustment for the value of pps_cb_qp_offset or pps_cr_qp_offset, according to whether the filtered chroma component is the Cb or Cr component. However, to avoid the need to vary the amount of the adjustment within the picture, the filtering process does not include an adjustment for the value of slice_cb_qp_offset or slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is equal to 1) for the value of CuQpOffsetCb, CuQpOffsetCr, or CuQpOffsetCbCr.
The value of the variable β′ is determined as specified in Table 8-18 based on the quantization parameter Q derived as follows:
Q=Clip3(0,63,QpC+(slice_beta_offset_div2<<1)) (8-1134)
where slice_beta_offset_div2 is the value of the syntax element slice_beta_offset_div2 for the slice that contains sample q0,0.
The variable β is derived as follows:
β=β′*(BitDepthC−8)) (8-1135)
The value of the variable tC′ is determined as specified in Table 8-18 based on the chroma quantization parameter Q derived as follows:
Q=Clip3(0,65,QpC+2*(bS−1)+(slice_tc_offset_div2<<1)) (8-1136)
where slice_tc_offset_div2 is the value of the syntax element slice_tc_offset_div2 for the slice that contains sample q 0 , 0 .
When making filter decisions for the depicted three samples (with solid circles), the QPs of the luma CU that covers the center position of the chroma CU including the three samples is selected. Therefore, for the 1st, 2nd and 3rd chroma sample (depicted in
In this way, how to select luma CU for chroma quantization/dequantization process is aligned with that for chroma filter decision process.
Inputs to this process are:
Output of this process is the (nTbW)×(nTbH) array d of scaled transform coefficients with elements d[x][y].
The quantization parameter qP is derived as follows:
qP=Qp′Y (8-950)
qP=Max(QpPrimeTsMin, Qp′Y) (8-951)
qP=Qp′CbCr (8-952)
qP=Qp′Cb (8-953)
qP=Qp′Cr (8-954)
Inputs to this process are:
Outputs of this process are the modified reconstructed picture after deblocking, i.e:
The variables firstCompldx and lastCompIdx are derived as follows:
firstCompIdx=(treeType==DUAL_TREE_CHROMA)?1:0 (8-1022)
lastCompIdx=(treeType==DUAL_TREE_LUMA∥ChromaArrayType==0)?0:2 (8-1023)
For each coding unit and each coding block per colour component of a coding unit indicated by the colour component index cIdx ranging from firstCompldx to lastCompIdx, inclusive, with coding block width nCbW, coding block height nCbH and location of top-left sample of the coding block (xCb, yCb), when cIdx is equal to 0, or when cIdx is not equal to 0 and edgeType is equal to EDGE_VER and xCb % 8 is equal 0, or when cIdx is not equal to 0 and edgeType is equal to EDGE_HOR and yCb % 8 is equal to 0, the edges are filtered by the following ordered steps:
. . .
[[5. The picture sample array recPicture is derived as follows:
. . .
The edge filtering process for one direction is invoked for a coding block as specified in clause 8.8.3.6 with the variable edgeType, the variable cIdx, the reconstructed picture prior to deblocking recPicture, the location (xCb, yCb), the coding block width nCbW, the coding block height nCbH, and the arrays bS, maxFilterLengthPs, and maxFilterLengthQs, as inputs, and the modified reconstructed picture recPicture as output.
Inputs to this process are:
Output of this process is a two-dimensional (nCbW)×(nCbH) array bS specifying the boundary filtering strength. The variables xDi, yDj, xN and yN are derived as follows:
. . .
For xD with i=0 . . . xN and yD, with j=0 . . . yN, the following applies:
. . .
Inputs to this process are:
Output of this process is the modified reconstructed picture after deblocking recPicture1.
. . .
1. The variable cQpPicOffset is derived as follows:
2.
3. The decision process for chroma block edges as specified in clause 8.8.3.6.3 is invoked with the chroma picture sample array recPicture, the location of the chroma coding block (xCb, yCb), the location of the chroma block (xB1, yB1) set equal to (xDk, yDm), the edge direction edgeType, the variable cQpPicOffset, the boundary filtering strength bS[xDk][yDm], and the variable maxFilterLengthCbCr set equal to maxFilterLengthPs[xDk][yDm] as inputs, and the modified variable maxFilterLengthCbCr, and the variable tC as outputs.
4. When maxFilterLengthCbCr is greater than 0, the filtering process for chroma block edges as specified in clause 8.8.3.6.4 is invoked with the chroma picture sample array recPicture, the location of the chroma coding block (xCb, yCb), the chroma location of the block (xB1, yB1) set equal to (xDk, yDm), the edge direction edgeType, the variable maxFilterLengthCbCr and the variable tC as inputs, and the modified chroma picture sample array recPicture as output.
This process is only invoked when ChromaArrayType is not equal to 0.
Inputs to this process are:
Outputs of this process are
The variable maxK is derived as follows:
maxK=(SubHeightC==1)?3:1 (8-1124)
maxK=(SubWidthC==1)?3:1 (8-1125)
The values pi and qi with =0 . . . maxFilterLengthCbCr and k=0 . . . maxK are derived as follows:
qk=recPicture
xCb+xB1+i][yCb+yB1+k] (8-1126)
pk=recPicture
xCb+xB1−i−1][yCb+yB1+k] (8-1127)
subSampleC=SubHeightC (8-1128)
ck=recPicture
xCb+xB1+k][yCb+yB1+i] (8-1129)
pk=recPicture
xCb+xB1+k][yCb+yB1−i−1] (8-1130)
subSampleC=SubWidthC (8-1131)
The variables QpQ and QpP are set equal to the QpY values of the coding units which include the coding blocks containing the sample q0,0 and p0,0, respectively.
The variable QpC is derived as follows:
qPi=(QpQ+QpP+1)>>1
(8-1132)
NOTE—The variable cQpPicOffset provides an adjustment for the value of pps_cb_qp_offset or pps_cr_qp_offset, according to whether the filtered chroma component is the Cb or Cr component. However, to avoid the need to vary the amount of the adjustment within the picture, the filtering process does not include an adjustment for the value of slice_cb_qp_offset or slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is equal to 1) for the value of CuQpOffsetCb, CuQpOffsetCr, or CuQpOffsetCbCr.
The value of the variable β′ is determined as specified in Table 8-18 based on the quantization parameter Q derived as follows:
Q=Clip3(0,63,QpC+(slice_beta_offset_div2<<1)) (8-1134)
where slice_beta_offset_div2 is the value of the syntax element slice_beta_offset_div2 for the slice that contains sample q0,0.
The variable β is derived as follows:
β=β′*(1<<(BitDepthC−8)) (8-1135)
The value of the variable tC′ is determined as specified in Table 8-18 based on the chroma quantization parameter Q derived as follows:
Q=Clip3(0,65,QpC+2*(bS−1)+(slice_tc_offset_div2<<1)) (9-1136)
where slice_tc_offset_div2 is the value of the syntax element slice_tc_offset_div2 for the slice that contains sample q0,0.
The variable tC is derived as follows:
t
C=(BitDepthC<10)?(tC′+2)>>(10−BitDepthC):tC′*(1<<(BitDepthC−8)) (8-1137)
When maxFilterLengthCbCr is equal to 1 and bS is not equal to 2, maxFilterLengthCbCr is set equal to 0.
When maxFilterLengthCbCr is equal to 3, the following ordered steps apply:
1. The variables n1, dpq0, dpq1
, dp
, dq
and
are derived as follows:
n1=(subSampleC==2)?1:3 (8-1138)
dp0=Abs(p
2,0−2*p
1,0+p
0,0) (8-1139)
dp1=Abs(p
2,n1−2*p
1,n1+p
0,n1) (8-1140)
dq0=Abs(q
2,0−2*q
1,0+q
0,0) (8-1141)
dq1=Abs(q
2,n1−2*q
1,a1+q
0,n1) (8-1142)
dpq0=dp0
+dq0
(8-1143)
dpq1=dp1
+dq1
(8-1144)
dp=dp0
+dp1
(8-1145)
dq=dq0
+dq1
(8-1146)
d=dpq0
+dpq1
(8-1147)
2.
3. The variables dSam0 and dSam1 are both set equal to 0.
4. When d is less than 0, the following ordered steps apply:
5. The variable maxFilterLengthCbCr is modified as follows:
This process is only invoked when ChromaArrayType is not equal to 0.
Inputs to this process are:
6.
Output of this process is the modified chroma picture sample array recPicture.
. . .
The values pi and qi with i=0 . . . maxFilterLengthCbCr and k=0 . . . maxK are derived as follows:
q
i,k=recPicturexCb+xB1+i][yCb+yB1+k] (8-1150)
p
i,k=recPicturexCb+xB1−i−1][yCb+yB1+k] (8-1151)
q
i,k=recPicturexCb+xB1+k][yCb+yB1+i] (8-1152)
p
i,k=recPicturexCb+xB1+k][yCb+yB1−i−1] (8-1153)
Depending on the value of edgeType, the following applies:
1. The filtering process for a chroma sample as specified in clause 8.8.3.6.9 is invoked with the variable maxFilterLengthCbCr, the sample values pi,k, qi,kwith i=0 . . . maxFilterLengthCbCr, the locations (xCb+xB1−i−1, yCb+yB1+k) and (xCb+xB1+i, yCb+yB1+k) with i =0 . . . maxFilterLengthCbCr−1, and the variable t c as inputs, and the filtered sample values pi′ and qi′ with i=0 . . . maxFilterLengthCbCr−1 as outputs.
2. The filtered sample values pi′ and qi′ with i=0 . . . maxFilterLengthCbCr−1 replace the corresponding samples inside the sample array recPicture as follows:
recPicturexCb+xB1+i][yCb+yB1+k]=qi′ (8-1154)
recPicturexCb+xB1−i−1][yCb+yB1+k=pi′ (8-1155)
1. The filtering process for a chroma sample as specified in clause 8.8.3.6.9 is invoked with the variable maxFilterLengthCbCr, the sample values pi,k, qi,k, with i=0 . . . maxFilterLengthCbCr, the locations (xCb+xB1+k, yCb+yB1−i−1) and (xCb+xB1+k, yCb+yB1+i), and the variable tC as inputs, and the filtered sample values pi′ and qi′ as outputs.
2. The filtered sample values pi′ and qi′ replace the corresponding samples inside the sample array recPicture as follows:
recPicture[xCb+xB1+k][yCb+yB1+i]=qi′ (8-1156)
recPicture[xCb+xB1+k][yCb+yB1−i−1]=pi′
. . .
[[The variables QpQ and QpP are set equal to the QpY values of the coding units which include the coding blocks containing the sample q0,0 and p0,0, respectively.
The variable QpC is derived as follows:
qPi=Clip3(0,63,((QpQ+QpP+1)>>1)+cQpPicOffset) (8-1132)
QpC=ChromaQpTable[cIdx−1][qPi] (8-1133)]]
. . .
[[The variables QpQ and QpP are set equal to the QpY values of the coding units which include the coding blocks containing the sample q0,0 and p0,0, respectively.
The variable QpC is derived as follows:
qPi=Clip3(0,63,((QpQ+QpP+1)>>1)+cQpPicOffset) (8-1132)
QpC=ChromaQpTable[cIdx−1][qPi] (8-1133)
NOTE—The variable cQpPicOffset provides an adjustment for the value of pps_cb_qp_offset or pps_cr_qp_offset, according to whether the filtered chroma component is the Cb or Cr component. However, to avoid the need to vary the amount of the adjustment within the picture, the filtering process does not include an adjustment for the value of slice_cb_qp_offset or slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is equal to 1) for the value of CuQpOffsetCb, CuQpOffsetCr, or CuQpOffsetCbCr.]]
In the present disclosure, the term “video processing” may refer to video encoding, video decoding, video compression or video decompression. For example, video compression algorithms may be applied during conversion from pixel representation of a video to a corresponding bitstream representation or vice versa. The bitstream representation of a current video block may, for example, correspond to bits that are either co-located or spread in different places within the bitstream, as is defined by the syntax. For example, a macroblock may be encoded in terms of transformed and coded error residual values and also using bits in headers and other fields in the bitstream.
It will be appreciated that the disclosed methods and techniques will benefit video encoder and/or decoder embodiments incorporated within video processing devices such as smartphones, laptops, desktops, and similar devices by allowing the use of the techniques disclosed in the present disclosure.
Some embodiments may be described using the following clause-based format.
1. A method of video processing, comprising:
performing a conversion between a video unit and a bitstream representation of the video unit, wherein, during the conversion, a deblocking filter is used on boundaries of the video unit such that when a chroma quantization parameter (QP) table is used to derive parameters of the deblocking filter, processing by the chroma QP table is performed on individual chroma QP values.
2. The method of clause 1, wherein chroma QP offsets are added to the individual chroma QP values subsequent to the processing by the chroma QP table.
3. The method of any of clauses 1-2, wherein the chroma QP offsets are added to values outputted by the chroma QP table.
4. The method of any of clauses 1-2, wherein the chroma QP offsets are not considered as input to the chroma QP table.
5. The method of clause 2, wherein the chroma QP offsets are at a picture-level or at a video unit-level.
6. A method of video processing, comprising:
7. The method of clause 6, wherein the chroma QP offsets used in the deblocking filter are associated with a coding method applied on a boundary of the video unit.
8. The method of clause 7, wherein the coding method is a joint coding of chrominance residuals (JCCR) method.
9. A method of video processing, comprising:
10. The method of clause 9, wherein the same luma coding unit covers a corresponding luma sample of a center position of the video unit, wherein the video unit is a chroma coding unit.
11. The method of clause 9, wherein a scaling process is applied to the video unit, and wherein one or more parameters of the deblocking filter depend at least in part on quantization/dequantization parameters of the scaling process.
12. The method of clause 11, wherein the quantization/dequantization parameters of the scaling process include the chroma QP offset.
13. The method of any of clauses 9-12, wherein the luma sample in the video unit is in the P side or Q side.
14. The method of clause 13, wherein the information pertaining to the same luma coding unit depends on a relative position of the coding unit with respect to the same luma coding unit.
15. A method of video processing, comprising:
16. The method of clause 15, wherein the indication is signaled conditionally in response to detecting one or more flags.
17. The method of clause 16, wherein the one or more flags are related to a JCCR enabling flag or a chroma QP offset enabling flag.
18. The method of clause 15, wherein the indication is signaled based on a derivation.
19. A method of video processing, comprising:
20. A method of video processing, comprising: performing a conversion between a video unit and a bitstream representation of the video unit, wherein, during the conversion, a deblocking filter is used on boundaries of the video unit such that chroma QP offsets are used in the deblocking filter, wherein a boundary strength (BS) of the deblocking filter is calculated without comparing reference pictures and/or a number of motion vectors (MVs) associated with the video unit at a P side boundary with reference pictures and/or a number of motion vectors (MVs) associated with the video unit at a Q side.
21. The method of clause 20, wherein the deblocking filter is disabled under one or more conditions.
22. The method of clause 21, wherein the one or more conditions are associated with: a magnitude of the motion vectors (MVs) or a threshold value.
23. The method of clause 22, wherein the threshold value is associated with at least one of: i. contents of the video unit, ii. a message signaled in DPS/SPS/VPS/PPS/APS/picture header/slice header/tile group header/Largest coding unit (LCU)/Coding unit (CU)/LCU row/group of LCUs/TU/PU block/Video coding unit, iii. a position of CU/PU/TU/block/Video coding unit, iv. a coded mode of blocks with samples along the boundaries, v. a transform matrix applied to the video units with samples along the boundaries, vi. a shape or dimension of the video unit, vii. an indication of a color format, viii. a coding tree structure, ix. a slice/tile group type and/or picture type, x. a color component, xi. a temporal layer ID, or xii. a profile/level/tier of a standard.
24. The method of clause 20, wherein different QP offsets are used for TS coded video units and non-TS coded video units.
25. The method of clause 20, wherein a QP used in a luma filtering step is related to a QP used in a scaling process of a luma block.
26. A video decoding apparatus comprising a processor configured to implement a method recited in one or more of clauses 1 to 25.
27. A video encoding apparatus comprising a processor configured to implement a method recited in one or more of clauses 1 to 25.
28. A computer program product having computer code stored thereon, the code, when executed by a processor, causes the processor to implement a method recited in any of clauses 1 to 25.
29. A method, apparatus or system described in the present disclosure.
As shown in
Source device 110 may include a video source 112, a video encoder 114, and an input/output (I/O) interface 116.
Video source 112 may include a source such as a video capture device, an interface to receive video data from a video content provider, and/or a computer graphics system for generating video data, or a combination of such sources. The video data may comprise one or more pictures. Video encoder 114 encodes the video data from 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. I/O interface 116 may include a modulator/demodulator (modem) and/or a transmitter. The encoded video data may be transmitted directly to destination device 120 via I/O interface 116 through network 130a. The encoded video data may also be stored onto a storage medium/server 130b for access by destination device 120.
Destination device 120 may include an I/O interface 126, a video decoder 124, and a display device 122.
I/O interface 126 may include a receiver and/or a modem. I/O interface 126 may acquire encoded video data from the source device 110 or the storage medium/server 130b. Video decoder 124 may decode the encoded video data. Display device 122 may display the decoded video data to a user. Display device 122 may be integrated with the destination device 120, or may be external to destination device 120 which be configured to interface with an external display device.
Video encoder 114 and 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 further standards.
Video encoder 200 may be configured to perform any or all of the techniques of this disclosure. In the example of
The functional components of video encoder 200 may include a partition unit 201, a prediction unit 202 which may include a mode select 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, video encoder 200 may include more, fewer, or different functional components. In an example, prediction unit 202 may include an intra block copy (IBC) unit. The IBC unit may perform prediction in an IBC mode in which at least one reference picture is a picture where the current video block is located.
Furthermore, some components, such as motion estimation unit 204 and motion compensation unit 205 may be highly integrated, but are represented in the example of
Partition unit 201 may partition a picture into one or more video blocks. Video encoder 200 and video decoder 300 may support various video block sizes.
Mode select unit 203 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra- or inter-coded block to a residual generation unit 207 to generate residual block data and to a reconstruction unit 212 to reconstruct the encoded block for use as a reference picture. In some example, Mode select unit 203 may select a combination of intra and inter prediction (CIIP) mode in which the prediction is based on an inter prediction signal and an intra prediction signal. Mode select 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-prediction.
To perform inter prediction on a current video block, 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. 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 buffer 213 other than the picture associated with the current video block.
Motion estimation unit 204 and 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.
In some examples, motion estimation unit 204 may perform uni-directional prediction for the current video block, and motion estimation unit 204 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. 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. 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. Motion compensation unit 205 may generate the predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.
In other examples, motion estimation unit 204 may perform bi-directional prediction for the current video block, 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. 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. 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. 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, motion estimation unit 204 may output a full set of motion information for decoding processing of a decoder.
In some examples, motion estimation unit 204 may not output a full set of motion information for the current video. Rather, 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, 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, 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 another video block.
In another example, 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, video encoder 200 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder 200 include advanced motion vector prediction (AMVP) and merge mode signaling.
Intra prediction unit 206 may perform intra prediction on the current video block. When intra prediction unit 206 performs intra prediction on the current video block, 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.
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 residual generation unit 207 may not perform the subtracting operation.
Transform processing 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 transform processing unit 208 generates a transform coefficient video block associated with the current video block, 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.
Inverse quantization unit 210 and 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. Reconstruction unit 212 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the prediction unit 202 to produce a reconstructed video block associated with the current block for storage in the buffer 213.
After reconstruction unit 212 reconstructs the video block, loop filtering operation may be performed reduce video blocking artifacts in the video block.
Entropy encoding unit 214 may receive data from other functional components of the video encoder 200. When entropy encoding unit 214 receives the data, 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
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). Entropy decoding unit 301 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 302 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 302 may, for example, determine such information by performing the AMVP and merge mode.
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.
Motion compensation unit 302 may use interpolation filters as used by video encoder 20 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 302 may determine the interpolation filters used by video encoder 200 according to received syntax information and use the interpolation filters to produce predictive blocks.
Motion compensation unit 302 may use some 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.
Intra prediction unit 303 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit 303 inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 301. Inverse transform unit 303 applies an inverse transform.
Reconstruction unit 306 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 302 or intra-prediction unit 303 to form decoded blocks. 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 buffer 307, which provides reference blocks for subsequent motion compensation.
The system 1800 may include a coding component 1804 that may implement the various coding or encoding methods described in the present disclosure. The coding component 1804 may reduce the average bitrate of video from the input 1802 to the output of the coding component 1804 to produce a coded representation of the video. The coding techniques are therefore sometimes called video compression or video transcoding techniques. The output of the coding component 1804 may be either stored, or transmitted via a communication connected, as represented by the component 1806. The stored or communicated bitstream (or coded) representation of the video received at the input 1802 may be used by the component 1808 for generating pixel values or displayable video that is sent to a display interface 1810. The process of generating user-viewable video from the bitstream representation is sometimes called video decompression. Furthermore, while certain video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by a decoder.
Examples of a peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HDMI) or Displayport, and so on. Examples of storage interfaces include serial advanced technology attachment (SATA), peripheral component interconnect (PCI), integrated drive electronics (IDE) interface, and the like. The techniques described in the present disclosure may be embodied in various electronic devices such as mobile phones, laptops, smartphones or other devices that are capable of performing digital data processing and/or video display.
In some embodiments, a value indicating the mode of the joint coding of chroma residuals is equal to 2. In some embodiments, the deblocking filter process further uses one or more quantization parameter offsets at a video unit level, the video unit comprising a picture, a slice, a tile, a brick, or a subpicture.
In some embodiments, the chroma quantization parameter is used for deblocking samples along a first side of the edge of the current block, and the chroma quantization parameter is based on a mode of the transform block that are on the first side. In some embodiments, the first side is referred to as P-side, the P-side comprising samples located above the edge in case the edge is a horizontal boundary or to the left of the edge in case the edge is a vertical boundary. In some embodiments, the chroma quantization parameter is used for deblocking samples along a second side of the edge of the current block, and the chroma quantization parameter is based on a mode of the transform block that are on the second side. In some embodiments, the second side is referred to as Q-side, the Q-side comprising samples located below the edge in case the edge is a horizontal boundary or to the right of the edge in case the edge is a vertical boundary.
In some embodiments, the chroma quantization parameter is determined based on whether a mode of joint coding of chroma residuals is applied. In some embodiments, the chroma quantization parameter is determined based on whether a mode of the joint coding of chroma residuals is equal to 2.
In some embodiments, the first chroma quantization parameter is equal to the second quantization parameter used in the scaling process minus the quantization parameter offset associated with the bit depth. In some embodiments, the first chroma quantization parameter used for deblocking samples along a first side of the edge of the current block. In some embodiments, the first side is referred to as P-side, the P-side comprising samples located above the edge in case the edge is a horizontal boundary or to the left of the edge in case the edge is a vertical boundary. In some embodiments, the first chroma quantization parameter used for deblocking samples along a second side of the edge of the current block. In some embodiments, the second side is referred to as Q-side, the Q- side comprising samples located below the edge in case the edge is a horizontal boundary or to the right of the edge in case the edge is a vertical boundary.
In some embodiments, the first chroma quantization parameter is equal to the second quantization parameter for a joint coding of chroma residuals used in the scaling process minus quantization parameter offset associated with the bit depth. In some embodiments, the first chroma quantization parameter is equal to the second quantization parameter for a chroma Cb component used in the scaling process minus quantization parameter offset associated with the bit depth. In some embodiments, the first chroma quantization parameter is equal to the second quantization parameter for a chroma Cr component used in the scaling process minus quantization parameter offset associated with the bit depth.
In some embodiments, the format rule specifies that the chroma quantization parameter is included at a coding unit level in case a size of the coding unit is larger than a virtual pipeline data unit. In some embodiments, the format rule specifies that the chroma quantization parameter is included at a transform unit level in case a size of the coding unit is larger than or equal to a virtual pipeline data unit. In some embodiments, the format rule specifies that the chroma quantization parameter is included at a coding unit level in case a size of the coding unit is larger than a maximum transform block size. In some embodiments, the format rule specifies that the chroma quantization parameter is included at a transform unit level in case a size of the coding unit is larger than or equal to a maximum transform block size. In some embodiments, the format rule further specifies that whether a joint coding of chroma residuals mode is applicable to a first coding unit of the one or more coding units is indicated at a coding unit level. In some embodiments, a transform block within the first coding unit inherits information about whether the joint coding of chroma residuals mode is applicable at the first coding unit level.
In some embodiments, during the conversion, a transform block within a coding unit inherits information about whether the joint coding of chroma residuals mode is applicable at the coding unit level.
In some embodiments, the conversion includes encoding the video into the bitstream representation. In some embodiments, the conversion includes decoding the bitstream representation into the video.
Some embodiments of the disclosed technology include making a decision or determination to enable a video processing tool or mode. In an example, when the video processing tool or mode is enabled, the encoder will use or implement the tool or mode in the processing of a block of video, but may not necessarily modify the resulting bitstream based on the usage of the tool or mode. That is, a conversion from the block of video to the bitstream representation of the video will use the video processing tool or mode when it is enabled based on the decision or determination. In another example, when the video processing tool or mode is enabled, the decoder will process the bitstream with the knowledge that the bitstream has been modified based on the video processing tool or mode. That is, a conversion from the bitstream representation of the video to the block of video will be performed using the video processing tool or mode that was enabled based on the decision or determination.
Some embodiments of the disclosed technology include making a decision or determination to disable a video processing tool or mode. In an example, when the video processing tool or mode is disabled, the encoder will not use the tool or mode in the conversion of the block of video to the bitstream representation of the video. In another example, when the video processing tool or mode is disabled, the decoder will process the bitstream with the knowledge that the bitstream has not been modified using the video processing tool or mode that was enabled based on the decision or determination.
The disclosed and other solutions, examples, embodiments, modules and the functional operations described in this disclosure can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this disclosure and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.
A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
The processes and logic flows described in this disclosure can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).
Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and compact disc, read-only memory (CD ROM) and digital versatile disc read-only memory (DVD-ROM) disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.
While the present disclosure contains many specifics, these should not be construed as limitations on the scope of any subject matter or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular techniques. Certain features that are described in the present disclosure in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in the present disclosure should not be understood as requiring such separation in all embodiments.
Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/CN2019/111115 | Oct 2019 | WO | international |
This application is a continuation of U.S. application Ser. No. 17/720,582, filed on Apr. 14, 2022, which is a continuation of International Patent Application No. PCT/US2020/055329, filed on Oct. 13, 2020, which claims the priority to and benefits of International Patent Application No. PCT/CN2019/111115, filed on Oct. 14, 2019. All the aforementioned patent applications are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17720582 | Apr 2022 | US |
| Child | 18519994 | US | |
| Parent | PCT/US2020/055329 | Oct 2020 | US |
| Child | 17720582 | US |
