WO2026012002A1

WO2026012002A1 - Motion vector coding improvements in dynamic mesh coding

Info

Publication number: WO2026012002A1
Application number: PCT/CN2025/098306
Authority: WO
Inventors: Jizheng Xu; Danying WANG
Original assignee: Douyin Vision Co Ltd; ByteDance Inc
Current assignee: Douyin Vision Co Ltd; ByteDance Inc
Priority date: 2024-07-08
Filing date: 2025-05-30
Publication date: 2026-01-15
Anticipated expiration: 2027-01-08

Abstract

A mechanism for processing video data is disclosed. The mechanism includes determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag). A conversion is performed between a visual media data and a bitstream based on the default operator.

Description

Motion Vector Coding Improvements In Dynamic Mesh Coding

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority to and benefits of International Patent Application No. PCT/CN2024/104124, filed on July 8, 2024, and International Patent Application No. PCT/CN2024/105432, filed on July 15, 2024. All of these applications are herein incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to generation, storage, and consumption of digital audio video media information in a file format.

BACKGROUND

Digital video accounts for the largest bandwidth used on the Internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, the bandwidth demand for digital video usage is likely to continue to grow.

SUMMARY

A first aspect relates to a method for processing video data comprising: determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) ; and performing a conversion between a visual media data and a bitstream based on the default operator.

A second aspect relates to an apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform any of the preceding aspects.

A third aspect relates to non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of the preceding aspects.

A fourth aspect relates to a non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) ; and generating a bitstream based on the determining.

A fifth aspect relates to a method for storing bitstream of a video comprising: determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) ; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

A sixth aspect relates to a method, apparatus, or system described in the present disclosure.

For the purpose of clarity, any one of the foregoing embodiments may be combined with any one or more of the other foregoing embodiments to create a new embodiment within the scope of the present disclosure.

These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

FIG. 1 is a block diagram illustrating a decoder design of dynamic mesh coding.

FIG. 2 is a block diagram illustrating a structure of a dynamic mesh coding test model.

FIG. 3 is a block diagram showing an example video processing system.

FIG. 4 is a block diagram of an example video processing apparatus.

FIG. 5 is a flowchart for an example method of video processing.

FIG. 6 is a block diagram that illustrates an example video coding system.

FIG. 7 is a block diagram that illustrates an example encoder.

FIG. 8 is a block diagram that illustrates an example decoder.

FIG. 9 is a schematic diagram of an example encoder.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or yet to be developed. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.
1. Initial discussion

This disclosure is related to improvements to motion picture experts group immersive (MPEG-I) video-based dynamic mesh coding. Specifically, it is related to the motion vector coding for basemesh sub-bitstream. It may be also applicable to other immersive video coding standards or codecs.
2. Further discussion

In computer graphics, a three-dimensional (3D) /immersive content can usually be represented by a 3D mesh and a texture map. Those mesh and texture data can be generated by a machine or can be converted from images captured by multiple cameras from different angles. Similar to two-dimensional (2D) video, when those 3D contents change with time, the mesh and texture data also change and comprises a sequence of dynamic mesh. The data volume of dynamic mesh are usually huge and make it difficult to store and transmit. To meet the requirement of applications that use dynamic mesh, Motion Picture Expert Group (MPEG) in short, issued a call for proposal [1] . To efficiently use the 2D codecs that are already available, one of the key requirements is to use the current 2D video coding standard to compress most data and keep other parts simple and of low complexity. Such a requirement can guarantee that the representation can take advantages of the 2D video hardware/software systems, without many efforts to redesign a specific system just for dynamic mesh.

MPEG received 5 responses to the call for proposal. So based on the tested technologies, a test model was built for the development of the planned dynamic mesh coding standard.

The latest test model of dynamic mesh coding (V-DMC) until this document is drafted can be found via this link http: //mpegx. int-evry. fr/software/MPEG/dmc/mpeg-vmesh-tm/-/tags/v5.0; and the latest working draft document is WD 6.0 [2] .
2.1 Data representation in dynamic mesh coding

FIG. 1 is a block diagram illustrating a decoder design of dynamic mesh coding. FIG. 1 shows a decoder design as described in WD 6.0 [2] . It can be seen that a dynamic mesh decoder receives 4 bitstreams and performs decoding to reconstruct the dynamic mesh plus texture signals. The first bitstream is to represent the base mesh, which is a decimated version of the original mesh. The second bitstream is to represent displacement vectors between the reconstructed base mesh and the original mesh. The displacement vectors are arranged as a 2D video and compressed with an 2D video coding standard compliant codec, or the displacement can also be coded using an arithmetic codec. The third bitstream is to represent the texture (or attribute map) . The attribute map is also arranged as a 2D video and compressed with an 2D video coding standard compliant codec. The design philosophy is to make the base mesh part small enough so that the module to process base mesh can be implemented simply. On the other hand, the displacement vectors and the attribute map accounts for most volume of the whole dynamic mesh data, which can be processed with the current dedicated highly efficient 2D video coding systems. Such a design can reduce the extra efforts to implement the dynamic mesh coding system and guarantee the high throughout and coding efficiency for the dynamic mesh data.
2.2 Test model of dynamic mesh coding

FIG. 2 is a block diagram illustrating a structure of a dynamic mesh coding test model. FIG. 2 shows the structure of an example dynamic mesh coding model. In the model, Draco is used to compress base mesh and the HEVC test model, e.g., HM, is used to compress displacement vectors and attribute map. However, it should be noted that other mesh or video coding systems can also be used in dynamic mesh coding.

The base mesh m is generated from the original mesh with a down-sampling scheme. Its quantized version m’ is then coded using Draco. The reconstrused base mesh m” can be obtained by inverse quantization of m’. Displacement vectors d’a re generated by making the difference between the original mesh and the subdivided version of m” using a subdivision scheme.
2.3 Basemesh coding

For a certain frame, the basemesh can be coded in three types: intra, inter and skip. For inter and skip basemesh, a reference basemesh frame is used to reconstruct the current basemesh.
2.4 Inter basemesh coding

In V-DMC, all vertices of a basemesh will be first ordered. A duplicated vertex is a vertex that has the same position as a previous vertex, called reference vertex, in the current basemesh. The motion vector of a duplicated vertex can be either derived to the same of that of the reference vertex or signalled in the bitstream. A flag, bmidu_mv_signalled_flag is used to control how the motion vector for a duplicated vertex is obtained. For a duplicated vertex, when bmidu_mv_signalled_flag is equal to 1, the motion vector is signalled in the bitstream; when bmidu_mv_signalled_flag is equal to 0, the motion vector is derived to be the same of that of the reference vertex.

The following text in [3] shows the syntax table of inter basemesh:
H.8.1.3.8 Basemesh inter submesh unit syntax

bm_inter_submesh_data_unit (submeshID, vertexCount) contains a portion of motion data of size unitSize as an ordered stream of bytes or bits within which the locations of unit boundaries are identifiable from patterns in the data. The format of such basemesh data is identified by bmptl_profile_codec_group_idc or by a component codec mapping SEI message.
H.8.1.3.9 Basemesh inter submesh data unit syntax

H.8.3.8.1 Basemesh inter submesh data unit default semantics

bmidu_derived_mv_present_flag [submeshID] indicates bmidu_mv_signalled_flag is present in the bitstream. If bmidu_derived_mv_present_flag [submeshID] is 0, bmidu_mv_signalled_flag [submeshID] [v] is always inferred as 1.

It is a requirement of bitstream conformance that if bmidu_derived_mv_present_flag [submeshID] is equal to 1 for a submesh with submesh ID equal to submeshID, mesh_deduplicate_method, if present in the corresponding intra submesh data unit, shall be equal to MESH_POSITION_DEDUP_NONE.

bmidu_mv_signalled_flag_count [submeshID] specifies the number of bmidu_mv_signalled_flag in the current submesh, with submesh ID equal to submeshID.

bmidu_mv_signalled_flag [submeshID] [d] indicates a motion vector for the vertex with index d, whose output of findIndexInArray () is not -1, is present in the bitstream. When bmidu_mv_signalled_flag [submeshID] [d] is not present in the bitstream, bmidu_mv_signalled_flag [submeshID] [d] is inferred as 1. bmidu_mv_signalled_flag [submeshID] [d] is used to derive BmiduMvFlag [submeshID] [v] variable, which indicates that a motion vector for the vertex with index v is present in the bitstream.

The BmiduMvFlag [submeshID] [v] variable is derived as follows:

where findIndexInArray () function is defined in subclause H. 5.

bmidu_skip_group_flag [submeshID] [g] equal to 1 specifies a motion vector associated with vertices in the group with index g of the current submesh, with submesh ID equal to submeshID, is skipped. bmidu_skip_group_flag [submeshID] [g] equal to 0 specifies a motion vector associated with vertices in the group with index g of the current submesh, with submesh ID equal to submeshID, is not skipped. When not present, bmidu_skip_group_flag [submeshID] [g] is inferred to be equal to 0.

bmidu_skip_group_component_flag [subMeshID] [g] [k] equal to 1 specifies decoding of k-th motion vector component, associated with vertices in the group with index g of the current submesh, with submesh ID equal to subMeshID, is skipped and the value of k-th motion vector component is inferred to be equal to 0. bmidu_skip_group_component_flag [subMeshID] [g] [k] equal to 0 specifies decoding of k-th motion vector component, associated with vertices in the group with index g of the current submesh, with submesh ID equal to subMeshID, is not skipped.

When bmidu_skip_group_flag [submeshID] [g] is equal to 0 and when the value of k is equal to 2 and bmidu_skip_group_component_flag [subMeshID] [g] [0] and bmidu_skip_group_component_flag [subMeshID] [g] [1] are both equal to 1, bmidu_skip_group_component_flag [subMeshID] [g] [2] shall take the default value equal to 0.

bmidu_mv_pred_mode_group [subMeshID] [g] [k] specifies whether an offset term is applied for the derivation of motion vector prediction. When bmidu_mv_pred_mode_group [subMeshID] [g] [k] is greater than 1 it specifies that an offset is applied to the derivation of the prediction of k-th component of motion vector with submesh ID equal to subMeshID, associated with groupindex, g. When bmidu_mv_pred_mode_group [subMeshID] [g] [k] is less or equal to 1 no offset is applied to the derivation of prediction of k-th component of motion vector with submesh ID submesh ID equal to subMeshID, associated with groupindex, g. The value of bmidu_mv_pred_mode_group [subMeshID] [g] [k] shall be in the range of 0 to 2

bmidu_mv_residual_abs_gt0 [submeshID] [v] [k] equal to 1 specifies the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID has a value higher than 0. bmidu_mv_residual_abs_gt0 [subMeshID] [v] [k] equal to 0 indicates the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to subMeshID, has a value equal to 0.

bmidu_mv_residual_sign [submeshID] [v] [k] equal to 1 specifies indicates whether the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID has a value greater or equal to 0. bmidu_mv_residual_sign [submeshID] [v] [k] equal to 0 indicates the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID has a value less than 0, When bmidu_mv_residual_sign [v] [k] is not present it shall be inferred to be equal to 1.

bmidu_mv_residual_abs_gt1 [submeshID] [v] [k] indicates whether the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID has an absolute value higher than one (when 1) , or not (when 0) . If bmidu_mv_residual_abs_gt1 [v] [k] is not present it shall be inferred to be equal to 0.

bmidu_mv_residual_abs_rem [submeshID] [v] [k] indicates the absolute value of the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID. When bmidu_mv_residual_abs_rem [v] [k] is not present it shall be inferred to be equal to 0.

The k-th component of the motion vector prediction residual VertexMotionVectorResiduals [v] [k] associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID is computed as follows:
VertexMotionVectorResiduals [v] [k] = bmidu_mv_residual_sign [v] [k] ? 1 : -1) *
(bmidu_mv_residual_abs_gt0 [v] [k] + bmidu_mv_residual_abs_gt1 [v] [k] +bmidu_mv_residual_abs_rem [v] [k] )
2.5 Basemesh motion vector coding in V-DMC TMM 7.0

In the V-DMC TMM 7.0 [4] , however, the motion vector coding is different from what is described in [2]. In TMM 7.0, duplicated vertices with motion vector derived are not included in a motion group. Only non-duplicated vertices and duplicated vertices with motion vector signalled are taken into account in motion groups.
2.6 Basemesh motion vector coding in V-DMC CD

In the V-DMC CD text [5] , the following syntax and semantics are described for motion vector coding,
H.8.3.3.9 Basemesh inter submesh unit syntax

H.8.5.8.1 Basemesh inter submesh data unit default semantics

bm_vertex_count [submeshID] indicates the number of vertices of submesh with submesh Id, submeshID.

It is a requirement of bitstream conformance that if bmidu_mv_signalled flag_count [submeshID] is larger than 0 for a submesh with submesh ID equal to submeshID, mesh_deduplicate_method, if present in the corresponding intra submesh data unit, shall be equal to MESH_POSITION_DEDUP_NONE.

The BmiduMvFlag [submeshID] [v] variable is derived as follows:

where findIndexInArray () function is defined in subclause H. 5.

bmidu_skip_group_comp_flag [subMeshID] [g] [k] equal to 1 specifies the k-th motion vector component, associated with vertices in the group with index g of the current submesh, with submesh ID equal to subMeshID, is inferred to be equal to 0. When bmidu_skip_group_comp_flag [subMeshID] [g] [k] is not present, bmidu_skip_group_comp_flag [subMeshID] [g] [k] is inferred to be equal to 0..

When bmidu_skip_group_flag [submeshID] [g] is equal to 0 and when the value of k is equal to 2 and bmidu_skip_group_comp_flag [subMeshID] [g] [0] and bmidu_skip_group_comp_flag [subMeshID] [g] [1] are both equal to 1, bmidu_skip_group_comp_flag [subMeshID] [g] [2] shall be equal to 0.

bmidu_mv_pred_mode_group [subMeshID] [g] [k] specifies the method used to predict the motion vector of the k-th motion vector component, associated with vertices in the group with index g of the current submesh, with submesh ID equal to subMeshID. The value of bmidu_mv_pred_mode_group [subMeshID] [g] [k] shall be in the range of 0 to 2
Table H-5 -Name association to bmidu_mv_pred_mode_group

bmidu_mv_residual_sign [submeshID] [v] [k] equal to 1 specifies whether the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID has a value greater or equal to 0. bmidu_mv_residual_sign [submeshID] [v] [k] equal to 0 specifies the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID has a value less than 0, When bmidu_mv_residual_sign [v] [k] is not present it shall be inferred to be equal to 1.

bmidu_mv_residual_abs_gt1 [submeshID] [v] [k] specifies whether the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID has an absolute value higher than one (when 1) , or not (when 0) . If bmidu_mv_residual_abs_gt1 [v] [k] is not present it shall be inferred to be equal to 0.

bmidu_mv_residual_abs_rem [submeshID] [v] [k] specifies the absolute value of the k-th component of the motion vector prediction residual associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID. When bmidu_mv_residual_abs_rem [v] [k] is not present it shall be inferred to be equal to 0.

The k-th component of the motion vector prediction residual VertexMotionVectorResiduals [v] [k] associated with the vertex with index v of the current submesh, with submesh ID equal to submeshID is computed as follows:
VertexMotionVectorResiduals [v] [k] = bmidu_mv_residual_sign [v] [k] ? 1 : -1) *
(bmidu_mv_residual_abs_gt0 [v] [k] + bmidu_mv_residual_abs_gt1 [v] [k] +bmidu_mv_residual_abs_rem [v] [k] )
H.9.4.5.3.2 Default Decoding process for inter submesh data units

Inputs to this process is current submesh ID, submeshID.

An output of this process is a struct, DecSubmesh, indicating the decoded submesh. The members of DecSubmesh are as follows:
submeshId, indicating the submeshId of the current submesh;
verCoordCount, indicating the number of vertex coordinates;
a one-dimensional (1D) array vertexNeighboursCounts, of size verCoordCount × 1, indicating the number of
neighbours for each vertex;
a 2D array vertexNeighbours, of size of size
verCoordCount × (bmsps_inter_mesh_max_num_neighbours_minus1 + 1) indicating the indices of its neighbours of each vertex;
a 1D array vDuplicated of size verCoordCount × 1, each element indicating the index of vertex with identical
coordinates as current vertex or -1 or -2, faceCount, indicating the number of faces;
a 2D array verCoords, indicating vertex coordinate values, of size verCoordCount × 3;
decVerCoordBitDepth, indicating the bit depth of the vertex coordinates;
a 2D array verCoordFaces, indicating vertex coordinates connectivity, of size faceCount × 3;
attributeCount, indicating the number of attributes; and
an array of structs of attributeCount, strAttributes, indicating the decoded attributes. The attrIdx-th element of the
strAttributes has the following members:
– attrType, indicating the type of the attribute;
– attrValueCount, indicating the number of values of the attribute;
– attrFaceCount, indicating the number of faces of the attribute;
– attrValueDimension, indicating the dimension of values of the attribute;
– attrValueBitDepth, indicating the bit depth of values of the attribute;
– attrValuePerVertex, indicating the attributes is per vertex;
– a 2D array attrValues, indicating values of the attribute, where the first dimension range is
0..attrValueCount -1, and the second dimension range is 0.. attrValueDimension; and
– a 2D array attrFacesArray, indicating the connectivity of the attribute, of size attrFaceCount × 3.

It is a requirement that any element of 2D array, verCoordFaces shall have values less than verCoordCount and that any elements of 2D array, attrValues [attIdx] shall have values less than attrValueCount [attIdx] .

It is a requirement that number of the reconstructed vertices verCoordCount shall be the same as the vertex count of the prediction frame.

First, refIdx is set to 0. the reference mesh, refSubmesh is derived as described in subclause H. 9.4.5.3.4. is invoked using the variables refIdx.

Then, DecSubmesh is initialized as follows:

The vertex neighbour table calculation in H. 9.4.5.3.3 with the variable refSubmesh. faceCount and the 2D array refSubmesh. verCoordFaces as inputs. A 1D array vertexNeighboursCounts of size refSubmesh. verCoordCount and a 2D array vertexNeighbours are outputs of the process. The size of the first dimension of the i-th element vertexNeighbours is refSubmesh. verCoordCount and the size of the second dimension of the i-th element vertexNeighbours is vertexNeighboursCounts [i] .
vN = 0

For v = 0.. bm_vertex_count [submeshID] -1, the following applies to update the v-th vertex coordinate

The group index g is derived as follows:
vB = v -vN
g = vB / (bmsps_inter_mesh_motion_group_size_minus1 + 1)

If bmidu_skip_group_flag [submeshID] [g] is equal to 1, then
currentSubmeshMotionVectors [v] [k] = 0, where k = 0.. 2

Otherwise, the prediction mode, mvPredMode [submeshID] [v] [k] where k = 0.. 2, is derived as follows:
mvPredMode [submeshID] [v] [k] = BmiduMvFlag [submeshID] [v] ? MV_DERIVED
:bmidu_mv_pred_mode_group [submeshID] [g] [k]
– if the prediction mode, mvPredMode [submeshID] [v] [k] is equal to MV_DERIVED, then
vN++
– vRef is derived as follow:

– if vRef = -1, then
currentSubmeshMotionVectors [v] [k] is set as 0
– else
currentSubmeshMotionVectors [v] [k] = currentSubmeshMotionVectors [vRef] [k]
– else if the prediction mode, mvPredMode [submeshID] [v] [k] is equal to MV_PRED_NONE, then
currentSubmeshMotionVectors [v] [k] = VertexMotionVectorResiduals [submeshID] [vB] [k]
– else (when bmidu_mv_pred_mode_group [submeshID] [v] is equal to MV_PRED_NEIGHBOUR) ,
currentSubmeshMotionVectors [v] [k] = VertexMotionVectorResiduals [submeshID] [vB] [k] +currentSubmeshPredictedMotionVectors [v] [k]

The predicted motion vector, currentSubmeshPredictedMotionVectors [v] [k] where k = 0.. 2 is derived by applying the following process:

– If the prediction mode, MvPredMode [submeshID] [v] is equal to MV_PRED_NONE, then
currentSubmeshMotionVectors [v] [k] =
VertexMotionVectorResiduals [submeshID] [v] [k]
– Otherwise (when bmidu_mv_pred_mode_group [submeshID] [v] is equal to
MV_PRED_NEIGHBOUR) ,
currentSubmeshMotionVectors [v] [k] =
VertexMotionVectorResiduals [submeshID] [vB] [k] +
currentSubmeshPredictedMotionVectors [v] [k]

The v-th vertex coordinate of the output struct, DecSubmesh is updated as follows:
– If v is less than or equal to refSubmesh. verCoordCount
DecSubmesh. verCoords [v] [k] =
currentSubmeshMotionVectors [v] [k] +
refSubmesh. verCoords [v] [k] , where k = 0.. 2
3. Technical problems solved by disclosed embodiments

An example design for dynamic mesh coding has the following problems:

First, when the number of bmidu_mv_signalled_flag in the current submesh, i.e. bmidu_mv_signalled_flag_count [submeshID] is smaller than the number of duplicated vertices, for the duplicated vertices without a corresponding bmidu_mv_signalled_flag, whether to signal or derive the motion vector is undefined.

Two, the parsing of current basemesh depends on the reference basemesh. Specifically, the number of vertices with motion vector signalled determines the number of motion groups and how many of the motion vector related syntax elements are parsed. Such a parsing dependency is not desirable.

Third, the MV coding efficiency can be further improved.

Fourth, bmidu_mv_signalled_flag_count does not have a range, which may lead to a negative number of vertices.

Fifth, the meaning of bmidu_mv_signalled_flag_count is vague.
4. A listing of solutions and embodiments

To address at least some of the above problems, methods as summarized below are disclosed. The items should be considered as examples to explain the general concepts and should not be interpreted in a narrow way. Furthermore, these designs can be applied individually or combined in any manner.
1. To address drawbacks of problem 1, for duplicated vertices that do not have a corresponding
bmidu_mv_signalled_flag, a default operator may be used to obtain the motion vector.
a. In one example, the default operator is to derive the motion vector from the reference vertex, which
corresponds to bmidu_mv_signalled_flag being 0.
b. Alternately, in one example, the default operator is to signal the motion vector in the current basemesh
bitstream, which corresponds to bmidu_mv_signalled_flag being 1.
2. To address drawbacks of problem 2, the number of duplicated vertices with motion vector derived may be
indicated in the bitstream of the current basemesh.
a. In one example, for inter basemesh, the number of duplicated vertices with motion vector derived shall
be able to be derived based on the information signalled in the bitstream of the current basemesh.
b. In one example, the number of duplicated vertices and the number of duplicated vertices with motion
vector signalled are indicated in the bitstream of the current basemesh.
i. In one example, the number of duplicated vertices with motion vector derived is equal to be
the number of duplicated vertices minus the number of duplicated vertices with motion vector signalled.
3. To address drawbacks of problem 3, for a series of vertices with a flag signalled if the corresponding motion
vector is signalled in the bitstream, a first part of the series of flags may be signalled and all the following flags are inferred to be equal to 0.
a. Alternatively, in one example, a first part of the series of flags may be signalled and all the following
flags are inferred to be equal to 1.
b. In one example, a syntax element is signalled to indicate the number of trailing zero of the series of
flags.
4. To address drawbacks of problem 3, for a series of vertices with a flag signalled if the corresponding motion
vector is signalled in the bitstream, zero-run numbers, which indicate how many consecutive 0 are present form the current position, may be used in coding the flag series.
a. Alternatively, in one example, one-run numbers, which indicate how many consecutive 1 are present
from the current position, may be used in coding the flag series.
b. In one example, one syntax element may be signalled to indicate the number of zero-runs for the whole
series of flags.
i. In one example, the number of zero-runs minus 1 may be signalled.
c. In one example, the flag immediately after a zero-run, except for the last zero-run, is decoded to be 1.
5. To address drawbacks of problem 3, a median operator may be used to derive the predictor for the current
vertex's motion vector.
a. In one example, when a vertex has 3 neighboring vertices with motion vector being MV0, MV1, MV2,
each component of the MV predictor for the current vertex is the median of the corresponding component of those 3 motion vectors.
b. In one example, when a vertex has less than 3 neighboring vertices, one vector's motion vector may be
repeated to increase the number of motion vectors to 3.
i. Alternatively, a zero-motion vector may be added to increase the number of motion vectors to
3.
c. In one example, when a vertex has more than 3 neighboring vertices, only three neighboring vertices
are considered.
i. In one example, furthermore, when a vertex has more than 3 neighboring vertices, only the
first three neighboring vertices are considered.
d. In one example, the median operator may be added as a new prediction mode for motion vector coding.
i. Alternatively, the median operator may replace an existing prediction mode for motion
vector coding.
1. In one example, the median operator may replace an existing prediction mode for
motion vector coding for vertices that have 3 or more neighboring vertices.
6. To address drawbacks of problem 1, it is specified that when absent, the value of bmidu_mv_signalled_flag is
inferred to be 0.
7. To address drawbacks of problem 4, a range constraint is set for bmidu_mv_signalled_flag_count
a. In one example, it is specified that bmidu_mv_signalled_flag_count shall be less than the number of
vertices in the current submesh.
8. To address drawbacks of problem 5, it is specified that the number of duplicated vertices may be indicated in
the bitstream.
a. Additionally, in one example, the number of non-duplicated vertices may be indicated in the bitstream.
i. In one example, a syntax element may be signalled to indicate the number of non-duplicated
vertices minus 1.
9. To address drawbacks of problem 3, a syntax element may be used to indicate if all bmidu_mv_signalled_flag
are 0 or not.
a. In one example, when there are vertices with derived motion vectors, the syntax element may be
signalled.
b. In one example, when the number of duplicate vertices is greater than 0, the syntax element may be
signalled.
c. In one example, a flag may be sent in the bitstream to specify if all bmidu_mv_signalled_flag of the
duplicated vertices are 0 or not.
10. The following constraint may be specified to avoid de-duplication and duplicate search happen together.
a. In one example, it is a requirement of bitstream conformance that if number of duplicate vertices is
larger than 0 for a submesh with submesh ID equal to submeshID, mesh_deduplicate_method, if present in the corresponding intra submesh data unit, shall be equal to MESH_POSITION_DEDUP_NONE.
b. In one example, it is a requirement of bitstream conformance that if
bmidu_mv_signalled_flag_count [submeshID] plus bmidu_mv_signalled_flag_trailing0 [submeshID] is larger than 0 for a submesh with submesh ID equal to submeshID, mesh_deduplicate_method, if present in the corresponding intra submesh data unit, shall be equal to MESH_POSITION_DEDUP_NONE.
5. Embodiments

Below are some example embodiments for the aspects summarized above in Section 4.

Most relevant parts that have been added or modified are in bold, and some of the deleted parts are in bold and italic fonts. There may be some other changes that are editorial in nature and thus not indicated.

The following text changes are based on WD 6.0 of V-DMC [3] .
5.1 Embodiment 1

This embodiment is for items 1 and 1. aas summarized above in Section 4.
H.8.3.8.1 Basemesh inter submesh data unit default semantics
...

The BmiduMvFlag [submeshID] [v] variable is derived as follows:

where findIndexInArray () function is defined in subclause H. 5.
5.2 Embodiment 2

This embodiment is for items 2, 2. a, 3, and 3. b as summarized above in Section 4.

5.3 Embodiment 3

This embodiment is for item 4 as summarized above in Section 4.

5.4 Embodiment 4

This embodiment is for items 4, 4. b, and 4. c summarized above in Section 4.

5.5 Embodiment 5

This embodiment is for item 6 summarized above in Section 4. The changes are based on the V-DMC CD text [5] .

bmidu_mv_signalled_flag [submeshID] [d] indicates a motion vector for the vertex with index d, whose output of findIndexInArray () is not -1, is present in the bitstream. When bmidu_mv_signalled_flag [submeshID] [d] is not present in the bitstream, bmidu_mv_signalled_flag [submeshID] [d] is inferred as 1 to be equal to 0. bmidu_mv_signalled_flag [submeshID] [d] is used to derive BmiduMvFlag [submeshID] [v] variable, which indicates that a motion vector for the vertex with index v is present in the bitstream.
5.6 Embodiment 6

This embodiment is for the items 7 and 7. asummarized above in Section 4. The changes are based on the V-DMC CD text [5] .

bmidu_mv_signalled_flag_count [submeshID] specifies the number of bmidu_mv_signalled_flag in the current submesh, with submesh ID equal to submeshID. The value of bmidu_mv_signalled_flag_count [submeshID] shall be less than bm_vertex_count [submeshID] .

It is a requirement of bitstream conformance that if bmidu_mv_signalled flag_count [submeshID] is larger than 0 for a submesh with submesh ID equal to submeshID, mesh_deduplicate_method, if present in the corresponding intra submesh data unit, shall be equal to MESH_POSITION_DEDUP_NONE.
5.7 Embodiment 7

This embodiment is for the items 8, 8. a, and 8. a. i summarized above in Section 4. The changes are based on the V-DMC CD text [5] .
H.8.3.3.9 Basemesh inter submesh unit syntax

H.8.5.8.1 Basemesh inter submesh data unit default semantics

bmidu_nondup_vertex_count_minus1 [submeshID] plus 1 specifies the number of non-duplicated vertices in the current submesh, with submesh ID equal to submeshID.

bmidu_dup_vertex_count [subMeshID] specifies the number of duplicated vertices in the current submesh, with submesh ID equal to submeshID.
...
H.9.4.5.3.2 Default Decoding process for inter submesh data units
...

For vB = 0.. bm_vertex_countbmidu_nondup_vertex_count_minus1 [submeshID] -1, the following applies to update the v-th vertex coordinate

The group index g is derived as follows:
vB = v -vN
v = vB + vN
g = vB / (bmsps_inter_mesh_motion_group_size_minus1 + 1)
...
5.8 Embodiment 8

This embodiment is for the items 9, 9. b, and 9. c summarized above in Section 4. The changes are based on the V-DMC CD text [5] .
H.8.3.3.9 Basemesh inter submesh unit syntax

H.8.5.8.1 Basemesh inter submesh data unit default semantics
...

bmidu_mv_signalled_flag_all0_flag [subMeshID] specifies if all the

The BmiduMvFlag [submeshID] [v] variable is derived as follows:

where findIndexInArray () function is defined in subclause H. 5.
...
5.9 Embodiment 9

This embodiment is for the items 10 and 10b summarized above in Section 4. The changes are based on the V-DMC CD text [5] .
H.8.3.3.9 Basemesh inter submesh unit syntax

H.8.5.8.1 Basemesh inter submesh data unit default semantics
...

It is a requirement of bitstream conformance that if bmidu_mv_signalled_flag_count [submeshID] plus bmidu_mv_signalled_flag_trailing0 [submeshID] is larger than 0 for a submesh with submesh ID equal to submeshID, mesh_deduplicate_method, if present in the corresponding intra submesh data unit, shall be equal to MESH_POSITION_DEDUP_NONE.

bmidu_mv_signalled_flag_trailing0 [submeshID] plus bmidu_mv_signalled_flag_count [submeshID] specifies the number of duplicated vertices in the current submesh, with submesh ID equal to submeshID.

The BmiduMvFlag [submeshID] [v] variable is derived as follows:

where findIndexInArray () function is defined in subclause H. 5.
6. References
[1] MPEG technical requirements, “CfP for. Dynamic Mesh Coding, ” ISO/IEC JTC 1/SC 29/WG 2 doc. no. N145,
in Oct. 2021.
[2] MPEG output document, “WD 6.0 of V-DMC, ” ISO/IEC JTC 1/SC 29/WG 7 doc. no. N00822, in Jan. 2024.
[3] MPEG output document, “Text of ISO/IEC FDIS 23090-5 2nd Edition Visual volumetric video-based coding
(V3C) and video-based point cloud compression (V-PCC) , ” ISO/IEC JTC 1/SC 29/WG 7 doc. no. N00553, in Jan. 2024.
[4] MPEG output document, “V-DMC TMM 7.0, ” ISO/IEC JTC 1/SC 29/WG 7 doc. no. N00811, in Jan. 2024.
[5] MPEG output document, “Text of ISO/IEC CD 23090-29 Video-based mesh coding, ” ISO/IEC JTC 1/SC 29/WG
7 doc. no. N00885, in Apr. 2024.

FIG. 3 is a block diagram showing an example video processing system 4000 in which various embodiments disclosed herein may be implemented. Various implementations may include some or all of the components of the system 4000. The system 4000 may include input 4002 for receiving video content. The video content may be received in a raw or uncompressed format, e.g., 8-or 10-bit multi-component pixel values, or may be in a compressed or encoded format. The input 4002 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON) , etc. and wireless interfaces such as Wi-Fi or cellular interfaces.

The system 4000 may include a coding component 4004 that may implement the various coding or encoding methods described in the present disclosure. The coding component 4004 may reduce the average bitrate of video from the input 4002 to the output of the coding component 4004 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 4004 may be either stored, or transmitted via a communication connected, as represented by the component 4006. The stored or communicated bitstream (or coded) representation of the video received at the input 4002 may be used by a component 4008 for generating pixel values or displayable video that is sent to a display interface 4010. 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 embodiments 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.

FIG. 4 is a block diagram of an example video processing apparatus 4100. The apparatus 4100 may be used to implement one or more of the methods described herein. The apparatus 4100 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on. The apparatus 4100 may include one or more processors 4102, one or more memories 4104 and video processing circuitry 4106. The processor (s) 4102 may be configured to implement one or more methods described in the present disclosure. The memory (memories) 4104 may be used for storing data and code used for implementing the methods and embodiments described herein. The video processing circuitry 4106 may be used to implement, in hardware circuitry, some embodiments described in the present disclosure. In some embodiments, the video processing circuitry 4106 may be at least partly included in the processor 4102, e.g., a graphics co-processor.

FIG. 5 is a flowchart for an example method 4200 of video processing. The method 4200 determines to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) at step 4202. A conversion between a visual media data and a bitstream based on the default operator at step 4204. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

It should be noted that the method 4200 can be implemented in an apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, such as video encoder 4400, video decoder 4500, and/or encoder 4600. In such a case, the instructions upon execution by the processor, cause the processor to perform the method 4200. Further, the method 4200 can be performed by a non-transitory computer readable medium comprising a computer program product for use by a video coding device. The computer program product comprises computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method 4200.

FIG. 6 is a block diagram that illustrates an example video coding system 4300 that may utilize the embodiments of this disclosure. The video coding system 4300 may include a source device 4310 and a destination device 4320. Source device 4310 generates encoded video data which may be referred to as a video encoding device. Destination device 4320 may decode the encoded video data generated by source device 4310 which may be referred to as a video decoding device.

Source device 4310 may include a video source 4312, a video encoder 4314, and an input/output (I/O) interface 4316. Video source 4312 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 4314 encodes the video data from video source 4312 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 4316 may include a modulator/demodulator (modem) and/or a transmitter. The encoded video data may be transmitted directly to destination device 4320 via I/O interface 4316 through network 4330. The encoded video data may also be stored onto a storage medium/server 4340 for access by destination device 4320.

Destination device 4320 may include an I/O interface 4326, a video decoder 4324, and a display device 4322. I/O interface 4326 may include a receiver and/or a modem. I/O interface 4326 may acquire encoded video data from the source device 4310 or the storage medium/server 4340. Video decoder 4324 may decode the encoded video data. Display device 4322 may display the decoded video data to a user. Display device 4322 may be integrated with the destination device 4320, or may be external to destination device 4320, which can be configured to interface with an external display device.

Video encoder 4314 and video decoder 4324 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.

FIG. 7 is a block diagram illustrating an example of video encoder 4400, which may be video encoder 4314 in the system 4300 illustrated in FIG. 6. Video encoder 4400 may be configured to perform any or all of the embodiments of this disclosure. The video encoder 4400 includes a plurality of functional components. The embodiments described in this disclosure may be shared among the various components of video encoder 4400. In some examples, a processor may be configured to perform any or all of the embodiments described in this disclosure.

The functional components of video encoder 4400 may include a partition unit 4401; a prediction unit 4402, which may include a mode select unit 4403, a motion estimation unit 4404, a motion compensation unit 4405, and an intra prediction unit 4406; a residual generation unit 4407; a transform processing unit 4408; a quantization unit 4409; an inverse quantization unit 4410; an inverse transform unit 4411; a reconstruction unit 4412; a buffer 4413; and an entropy encoding unit 4414.

In other examples, video encoder 4400 may include more, fewer, or different functional components. In an example, prediction unit 4402 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 4404 and motion compensation unit 4405 may be highly integrated, but are represented in the example of video encoder 4400 separately for purposes of explanation.

Partition unit 4401 may partition a picture into one or more video blocks. Video encoder 4400 and video decoder 4500 may support various video block sizes.

Mode select unit 4403 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 4407 to generate residual block data and to a reconstruction unit 4412 to reconstruct the encoded block for use as a reference picture. In some examples, mode select unit 4403 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 4403 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 4404 may generate motion information for the current video block by comparing one or more reference frames from buffer 4413 to the current video block. Motion compensation unit 4405 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 4413 other than the picture associated with the current video block.

Motion estimation unit 4404 and motion compensation unit 4405 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 4404 may perform uni-directional prediction for the current video block, and motion estimation unit 4404 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. Motion estimation unit 4404 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 4404 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 4405 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 4404 may perform bi-directional prediction for the current video block, motion estimation unit 4404 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 4404 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 4404 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 4405 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 4404 may output a full set of motion information for decoding processing of a decoder. In some examples, motion estimation unit 4404 may not output a full set of motion information for the current video. Rather, motion estimation unit 4404 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 4404 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 4404 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 4500 that the current video block has the same motion information as another video block.

In another example, motion estimation unit 4404 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 4500 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 4400 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder 4400 include advanced motion vector prediction (AMVP) and merge mode signaling.

Intra prediction unit 4406 may perform intra prediction on the current video block. When intra prediction unit 4406 performs intra prediction on the current video block, intra prediction unit 4406 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 4407 may generate residual data for the current video block by subtracting 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 4407 may not perform the subtracting operation.

Transform processing unit 4408 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 4408 generates a transform coefficient video block associated with the current video block, quantization unit 4409 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 4410 and inverse transform unit 4411 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 4412 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the prediction unit 4402 to produce a reconstructed video block associated with the current block for storage in the buffer 4413.

After reconstruction unit 4412 reconstructs the video block, the loop filtering operation may be performed to reduce video blocking artifacts in the video block.

Entropy encoding unit 4414 may receive data from other functional components of the video encoder 4400. When entropy encoding unit 4414 receives the data, entropy encoding unit 4414 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.

FIG. 8 is a block diagram illustrating an example of video decoder 4500 which may be video decoder 4324 in the system 4300 illustrated in FIG. 6. The video decoder 4500 may be configured to perform any or all of the embodiments of this disclosure. In the example shown, the video decoder 4500 includes a plurality of functional components. The embodiments described in this disclosure may be shared among the various components of the video decoder 4500. In some examples, a processor may be configured to perform any or all of the embodiments described in this disclosure.

In the example shown, video decoder 4500 includes an entropy decoding unit 4501, a motion compensation unit 4502, an intra prediction unit 4503, an inverse quantization unit 4504, an inverse transformation unit 4505, a reconstruction unit 4506, and a buffer 4507. Video decoder 4500 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 4400.

Entropy decoding unit 4501 may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data) . Entropy decoding unit 4501 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 4502 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 4502 may, for example, determine such information by performing the AMVP and merge mode.

Motion compensation unit 4502 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 4502 may use interpolation filters as used by video encoder 4400 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 4502 may determine the interpolation filters used by video encoder 4400 according to received syntax information and use the interpolation filters to produce predictive blocks.

Motion compensation unit 4502 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 coded block, and other information to decode the encoded video sequence.

Intra prediction unit 4503 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit 4504 inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 4501. Inverse transform unit 4505 applies an inverse transform.

Reconstruction unit 4506 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 4502 or intra prediction unit 4503 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 4507, which provides reference blocks for subsequent motion compensation/intra prediction and also produces decoded video for presentation on a display device.

FIG. 9 is a schematic diagram of an example encoder 4600. The encoder 4600 is suitable for implementing the techniques of VVC. The encoder 4600 includes three in-loop filters, namely a deblocking filter (DF) 4602, a sample adaptive offset (SAO) 4604, and an adaptive loop filter (ALF) 4606. Unlike the DF 4602, which uses predefined filters, the SAO 4604 and the ALF 4606 utilize the original samples of the current picture to reduce the mean square errors between the original samples and the reconstructed samples by adding an offset and by applying a finite impulse response (FIR) filter, respectively, with coded side information signaling the offsets and filter coefficients. The ALF 4606 is located at the last processing stage of each picture and can be regarded as a tool trying to catch and fix artifacts created by the previous stages.

The encoder 4600 further includes an intra prediction component 4608 and a motion estimation/compensation (ME/MC) component 4610 configured to receive input video. The intra prediction component 4608 is configured to perform intra prediction, while the ME/MC component 4610 is configured to utilize reference pictures obtained from a reference picture buffer 4612 to perform inter prediction. Residual blocks from inter prediction or intra prediction are fed into a transform (T) component 4614 and a quantization (Q) component 4616 to generate quantized residual transform coefficients, which are fed into an entropy coding component 4618. The entropy coding component 4618 entropy codes the prediction results and the quantized transform coefficients and transmits the same toward a video decoder (not shown) . Quantization components output from the quantization component 4616 may be fed into an inverse quantization (IQ) components 4620, an inverse transform component 4622, and a reconstruction (REC) component 4624. The REC component 4624 is able to output images to the DF 4602, the SAO 4604, and the ALF 4606 for filtering prior to those images being stored in the reference picture buffer 4612.

A listing of solutions preferred by some examples is provided next.

The following solutions show examples of embodiments discussed herein.

1. A method for processing media data comprising: determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) ; and performing a conversion between a visual media data and a bitstream based on the default operator.

2. The method of claim 1, wherein the default operator is used to derive the motion vector from a reference vertex, which corresponds to bmidu_mv_signalled_flag being 0.

3. The method of any of claims 1-2, wherein the default operator is used to signal the motion vector in a current basemesh bitstream, which corresponds to bmidu_mv_signalled_flag being 1.

4. The method of any of claims 1-3, wherein the number of duplicated vertices with motion vector derived are indicated in the bitstream of a current basemesh.

5. The method of any of claims 1-4, wherein the number of duplicated vertices with motion vectors derived for inter basemesh is determined based on information signalled in the bitstream of the current basemesh.

6. The method of any of claims 1-5, wherein the bitstream of the current basemesh indicates the number of duplicated vertices and the number of duplicated vertices with signalled motion vector.

7. The method of any of claims 1-6, wherein the number of duplicated vertices with derived motion vectors is equal to be the number of duplicated vertices minus the number of duplicated vertices with signalled motion vector.

8. The method of any of claims 1-7, wherein for a series of vertices with a signalled flag when the corresponding motion vector is signalled in the bitstream, a first part of the series of flags is signalled and all following flags are inferred to be equal to 0.

9. The method of any of claims 1-8, wherein a first part of the series of flags are signalled and all the following flags are inferred to be equal to 1, or wherein a syntax element is signalled to indicate the number of trailing zeros of the series of flags.

10. The method of any of claims 1-9, wherein for a series of vertices with a signalled flag when the corresponding motion vector is signalled in the bitstream, zero-run numbers, which indicate how many consecutive 0 are present form the current position, are used in coding the flag series.

11. The method of any of claims 1-10, wherein one-run numbers, which indicate how many consecutive 1 are present from the current position, are used in coding the flag series.

12. The method of any of claims 1-11, wherein a median operator is used to derive the predictor for the current vertex's motion vector.

13. The method of any of claims 1-12, wherein when a vertex has 3 neighboring vertices with motion vector being motion vector (MV) zero (MV0) , MV one (MV1) , and MV two (MV2) , each component of a MV predictor for the current vertex is the median of the corresponding component of those 3 motion vectors.

14. The method of any of claims 1-13, wherein one vector's motion vector is repeated to increase the number of motion vectors to 3 when a vertex has less than 3 neighboring vertices, or wherein a zero-motion vector is added to increase the number of motion vectors to 3.

15. The method of any of claims 1-14, wherein only three neighboring vertices are considered when a vertex has more than 3 neighboring vertices, or wherein only the first three neighboring vertices are considered when a vertex has more than 3 neighboring vertices.

16. The method of any of claims 1-15, wherein a median operator is added as a prediction mode for motion vector coding, or wherein a median operator replaces a prediction mode for motion vector coding.

17. An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of claims 1-16.

18. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of claims 1-16.

19. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) ; and generating a bitstream based on the determining.

20. A method for storing bitstream of a video comprising: determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) ; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

21. A method, apparatus, or system described in the present disclosure.

In the solutions described herein, an encoder may conform to the format rule by producing a coded representation according to the format rule. In the solutions described herein, a decoder may use the format rule to parse syntax elements in the coded representation with the knowledge of presence and absence of syntax elements according to the format rule to produce decoded video.

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. Furthermore, during conversion, a decoder may parse a bitstream with the knowledge that some fields may be present, or absent, based on the determination, as is described in the above solutions. Similarly, an encoder may determine that certain syntax fields are or are not to be included and generate the coded representation accordingly by including or excluding the syntax fields from the coded representation.

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 the present disclosure. 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.

A first component is directly coupled to a second component when there are no intervening components, except for a line, a trace, or another medium between the first component and the second component. The first component is indirectly coupled to the second component when there are intervening components other than a line, a trace, or another medium between the first component and the second component. The term “coupled” and its variants include both directly coupled and indirectly coupled. The use of the term “about” means a range including ±10%of the subsequent number unless otherwise stated.

While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled may be directly connected or may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

A method for processing media data, comprising:

performing a conversion between media data and a media data file according to a rule,

wherein the rule specifies to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) .
The method of claim 1, wherein a median operator is added as a prediction mode for motion vector coding, and wherein the median operator replaces a prediction mode for motion vector coding for vertices that have three or more neighboring vertices.
The method of any of claims 1-2, wherein the rule specifies that, when absent, a value of bmidu_mv_signalled_flag is inferred to be 0.
The method of any of claims 1-3, wherein the rule specifies that a range constraint is set for bmidu_mv_signalled_flag_count.
The method of any of claims 1-4, wherein bmidu_mv_signalled_flag_count shall be less than a number of vertices in a current submesh.
The method of any of claims 1-5, wherein the rule specifies that a number of duplicated vertices is indicated in a bitstream.
The method of any of claims 1-6, wherein the rule specifies that a number of non-duplicated vertices is indicated in the bitstream.
The method of any of claims 1-7, wherein a first syntax element is signalled in the bitstream to indicate the number of non-duplicated vertices minus 1.
The method of any of claims 1-8, wherein a second syntax element indicates whether or not all bmidu_mv_signalled_flag are equal to 0.
The method of any of claims 1-9, wherein the second syntax element is signalled when vertices with derived motion vectors are present, or wherein the second syntax element is signalled when the number of duplicated vertices is greater than 0.
The method of any of claims 1-10, wherein a flag in the bitstream specifies whether or not all bmidu_mv_signalled_flag of the duplicated vertices are equal to 0.
The method of any of claims 1-11, wherein the rule specifies a constraint to avoid de-duplication such that duplicate searches happen together.
The method of any of claims 1-12, wherein the rule specifies that if the number of duplicate vertices is greater than 0 for a submesh with submesh ID equal to submeshID, mesh_deduplicate_method, if present in a corresponding intra submesh data unit, shall be equal to MESH_POSITION_DEDUP_NONE.
The method of any of claims 1-13, wherein the rule specifies that if bmidu_mv_signalled_flag_count [submeshID] plus bmidu_mv_signalled_flag_trailing0 [submeshID] is greater than 0 for a submesh with submesh ID equal to submeshID, mesh_deduplicate_method, if present in the corresponding intra submesh data unit, shall be equal to MESH_POSITION_DEDUP_NONE.
The method of any of claims 1-14, wherein the conversion includes encoding the media data into the media data file.
The method of any of claims 1-14, wherein the conversion includes decoding the media data from the media data file.
An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of claims 1-16.
A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of claims 1-16.
A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:

determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) ; and

generating a bitstream based on the determining.
A method for storing bitstream of a video, comprising:

determining to use a default operator to obtain a motion vector for duplicated vertices that do not have a corresponding basemesh inter submesh data unit motion vector signalled flag (bmidu_mv_signalled_flag) ;

generating a bitstream based on the determining; and

storing the bitstream in a non-transitory computer-readable recording medium.