Carriage of dynamic system stream unit header size precision information for volumetric video

Abstract

Point cloud encoding and decoding systems and methods. In an example encoding method, at least a first track comprising a plurality of samples including point cloud information is encoded in a container file, such as an ISOBMFF file. A first sample group description box associated with the first track is encoded where the first sample group description box including at least a first sample group description entry and a second sample group description entry. The first sample group description entry stores first unit header size precision information and the second sample group description entry stores second unit header size precision information different from the first unit header size precision information. A first sample-to-group box is encoded, and it associates a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

Description

CARRIAGE OF DYNAMIC SYSTEM STREAM UNIT HEADER SIZE PRECISION INFORMATION FOR VOLUMETRIC VIDEOCROSS-REFERENCE

[0001] This application claims the priority of European Patent Application No. 23306718.0, filed 6 October 2023, entitled “Carriage of Dynamic System Stream Unit Header Size Precision Information for Volumetric Video,” which is incorporated herein by reference in its entirety.BACKGROUND

[0002] High-quality 3D point clouds have recently emerged as an advanced representation of immersive media. A point cloud consists of a set of points represented in the 3D space using coordinates indicating the location of each point along with one or more attributes, such as the color associated with each point, transparency, time of acquisition, reflectance of laser or material property, etc. Point clouds can be captured in several ways. For example, one technique for capturing point clouds is using multiple cameras and depth sensors. Light Detection and Ranging (LiDAR) laser scanners are also commonly used for capturing point clouds. The number of points required to realistically reconstruct objects and scenes using point clouds can be on the order of millions (or even billions). Therefore, efficient representation and compression is desirable for storing and transmitting point cloud data.

[0003] In their uncompressed form, volumetric videos are represented by a large amount of data. The ISO / IEC 23090-5 Visual Volumetric Video-based Coding (V3C) specification leverages the compression efficiency of existing 2D video codecs to reduce the amount of data needed for storage and transmission of volumetric videos. A V3C encoder converts volumetric frames into a collection of 2D image sequences and associated metadata that enable the reconstruction of the volumetric frames, known as atlas data. The resulting 2D image sequences are subsequently coded using traditional video or image encoders, e.g., the ISO / IEC 14496-10 (H.264 / AVC), ISO / IEC 23008-2 (HEVC), or ISO / IEC 23090-3 (WC) international standards. The atlas data is coded with mechanisms specified in the ISO / IEC 23090-5 specification. V3C is a generic mechanism for volumetric video coding, and it can be used by different applications targeting volumetric content compression, such as point clouds, immersive videos, and meshrepresentations of visual volumetric frames. Examples of such applications include Video-based Point Cloud Compression (V-PCC), and MPEG Immersive Video (MIV).

[0004] The V3C specification utilizes a high-level syntax (HLS) syntax design known from traditional 2D video codecs to represent the coded atlas data. Coded atlas data are represented by a sequence of Network Abstraction Layer (NAL) units.

[0005] Recent advances in technologies in capturing and rendering 3D points have enabled novel applications in the areas of tele-presence, virtual reality, and large-scale dynamic 3D maps. The 3D Graphics subgroup of ISO / IEC JTC1 / SC29 / WG7 is currently working on the development of two 3D point cloud compression (PCC) standards: a geometry-based compression standard for static point clouds and LiDAR captured time-varying sparse point clouds, and a video-based compression standard for dynamic point clouds. The goal of these standards is to support efficient and interoperable storage and transmission of 3D point clouds. One of the goals of these standards is to provide support for lossy and / or lossless coding of point cloud geometry coordinates and attributes. The WG7 has published the FDIS version of the ISO / IEC 23090-5 standard for video-based compression of dynamic point clouds. The MPEG Systems workgroup (ISO / IEC / SC29 / WG3) has developed a standard for carriage of V3C data (ISO / IEC 23090-10) and has published the FDIS version.SUMMARY

[0006] An example point cloud encoding method comprises: encoding, in a container file (such as an ISOBMFF file), at least a first track comprising a plurality of samples including point cloud information; encoding, in the container file, a first sample group description box associated with the first track, the first sample group description box including at least a first sample group description entry and a second sample group description entry; wherein the first sample group description entry stores first unit header size precision information and the second sample group description entry stores second unit header size precision information different from the first unit header size precision information; and encoding, in the container file, a first sample-to-group box associating a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

[0007] The first track may be, for example, an atlas track, a V3C bitstream track, or an atlas tile track.

[0008] In some embodiments, the unit header size precision information is system stream network abstraction layer (NAL) unit header size precision information.

[0009] In some embodiments, the unit header size precision information is system stream V3C unit header size precision information.

[0010] Some embodiments further include: encoding, in the container file, at least a second track comprising a plurality of samples including point cloud information; encoding, in the container file, a second sample group description box associated with the second track, the second sample group description box including at least a third sample group description entry and a fourth sample group description entry; wherein the third sample group description entry stores third unit header size precision information and the fourth sample group description entry stores fourth unit header size precision information different from the third unit header size precision information; and encoding, in the container file, a second sample-to-group box associating a third plurality of the samples with the third sample group description entry and the fourth plurality of samples with the fourth sample group description entry.

[0011] A decoding method according to some embodiments includes: decoding, from a container file, at least a first track comprising a plurality of samples including point cloud information; decoding, from the container file, a first sample group description box associated with the first track, the first sample group description box including at least a first sample group description entry and a second sample group description entry; wherein the first sample group description entry stores first unit header size precision information and the second sample group description entry stores second unit header size precision information different from the first unit header size precision information; and decoding, from the container file, a first sample-to-group box associating a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

[0012] Example embodiments further include the following: corresponding decoding techniques, apparatus comprising one or more processors configured to perform the methods herein, apparatus comprising at least one processor and a computer-readable medium storing instructions for performing the methods described herein, a computer-readable medium storing a point cloud encoded according to the methods herein, and a signal conveying a point cloud encoded according to the methods herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 illustrates a V3C bitstream structure as a sequence of V3C units.

[0014] FIG. 2 illustrates an atlas frame partitioned into 24 tiles and 9 tile groups.

[0015] FIG. 3 illustrates a multi-track V3C Container Structure.

[0016] FIG. 4 illustrates an example of using a ‘vsuh’ sample group in a multi-track V3C file according to an example embodiment.

[0017] FIG. 5 illustrates an example of using a ‘vsuh’ sample group in a single-track V3C file according to an example embodiment.

[0018] FIG. 6 illustrates an example of using ‘vsuh’ sample group in a V3C file with atlas track and multiple atlas tile tracks according to an example embodiment.

[0019] FIG. 7 is a block diagram of an example of a system in which various aspects and embodiments are implemented.DETAILED DESCRIPTIONOverview of video-based point cloud compression.

[0020] FIG. 1 illustrates the structure of the bitstream for the video-based point cloud compression (V-PCC). In ISO / IEC 23090-5, the V3C bitstream is composed of a sequence of V3C units, as shown in FIG. 1. Each V3C unit has a V3C unit header and a V3C unit payload. The V3C unit header describes the V3C unit type. Supported V3C unit types are given in Table 1 . The Attribute Video Data V3C unit header specifies the attribute type and its index, allowing multiple instances of the same attribute type to be supported. Table 2 specifies the supported V3C attribute types. The occupancy, geometry, and attribute Video Data unit payloads correspond to video data units (e.g., HEVC NAL unit) that are capable of being decoded by an appropriate video decoder. The video decoder corresponding to each video-coded component sub-bitstream (i.e., occupancy, geometry, or attribute sub-stream) is signaled in the V3C parameter set.Table 1. V3C unit types.Table 2. V3C attribute types.

[0021] The V3C bitstream high-level syntax (HLS) supports the use of data arranging tiles into tile groups in atlas frames. An atlas frame is divided into one or more tile rows and one or more tile columns. A tile is a rectangular region of an atlas frame. A tile group contains a number of tiles of an atlas frame that may be independently decodable. FIG. 2 shows a tile group partitioning example for an atlas frame (specifically, an atlas frame partitioned into 24 tiles and 9 tile groups). In current implementations, only rectangular tile groups are supported. Therefore, a tile group contains a number of tiles of an atlas frame that collectively form a rectangular region of the atlas frame.

[0022] The ISO / IEC DIS 23090-5 specification also includes several supplemental enhancement information (SEI) messages that can be signaled in a V3C bitstream to associate patches or volumetric rectangles within the atlas frame to objects within the scene represented by the point cloud. These SEI messages also enable annotating, labeling, and adding properties to these objects. Objects may correspond to "real" objects (physical objects within a scene) or conceptual objects that may relate to physical or other properties. Objects may be associated with different parameters, or properties, which may also correspond to information provided during the creation or editing process of the point cloud or scene graph. The specification supports the use of information defining dependency relationships between the different objects (e.g., one object may be part of another object).

[0023] Objects within a point cloud may be persistent in time or can be updated at any time / frame while the associated information may persist from that point onward. Multiple patches or 2D volumetric rectangles, which can contain themselves multiple patches, could be associated with a single object or multiple objects.Overview of the ISO Base Media File Format.

[0024] Within the ISO / IEC 14496 (MPEG-4) standard there are several parts that define file formats for the storage of time-based media. These are all based on and derived from the ISO Base Media File Format (ISOBMFF), which is a structural, media-independent definition. ISOBMFF contains structural and media data information mainly for timed presentations of media data such as audio, video, etc. There is also support for un-timed data, such as meta-data at different levels within the file structure. The logical structure of the file is of a movie that in turn contains a set of time-parallel tracks. The time structure of the file is that the tracks contain sequences of samples in time, and those sequences are mapped into the timeline of the overall movie. ISOBMFF is based on the concept of box-structured files. A box-structured file consists of a series of boxes (sometimes called atoms), which have a size and a type. The types are 32-bit values and usually chosen to be four printable characters, also known a four-character code(4CC). Un-timed data may be contained in a metadata box, at the file level, or attached to the movie box or one of the streams of timed data, called tracks, within the movie.

[0025] Among the top-level boxes within an ISOBMFF container is the MovieBox ('moov') which contains metadata for the continues media streams present in the file. These metadata are signaled within the hierarchy of boxes in the Movie box, e.g., within the TrackBox ('trak'). A track represents a continuous media stream that is present in the file. The media stream itself consists of a sequence of samples, such as audio or video access units of an elementary media stream. The samples are enclosed within a MediaDataBox ('mdat') that is present at the top-level of the container. The metadata for each track includes a list of sample description entries, each providing the coding or encapsulation format used in the track and the initialization data for processing that format. Each sample is associated with one of the sample description entries of the track. ISO / IEC 14496-12 provides a tool for defining an explicit timeline map for each track. This is known as an edit list and is signalled using an EditListBox with the following syntax, where each entry defines part of the track time-line: by mapping part of the composition timeline, or by indicating ‘empty’ time (portions of the presentation timeline that map to no media, an ‘empty’ edit). aligned ( 8 ) clas s EditL is tBox extends Ful lBox ( ' e ls t ' , vers ion, f lags ) { uns igned int ( 32 ) entry_count ; for ( i=l ; i <= entry_count ; i++ ) { i f (vers ion==l ) { uns igned int ( 64 ) edit_durat ion; int ( 64 ) media_t ime ; } e ls e { / / vers ion==0 uns igned int ( 32 ) edit_durat ion; int ( 32 ) media_time ; } int ( 16 ) media_rate_integer ; int ( 16 ) media_rate_f ract ion = 0 ; } }

[0026] ISOBMFF provides a mechanism to handle situations where the file author requires certain actions such as post-processing activities on the player or the Tenderer. In the case of video streams, this is done through the use of restricted video scheme tracks. When a video track is a restricted video scheme track, as defined in subclause 8.15 of the ISO / IEC 14496-12 standard, this signals post-decoder requirements on the track. A track is transformed into a restricted video scheme track by setting its sample entry code to the four-character code (4CC) ‘resv’ and adding a RestrictedSchemelnfoBox to its sample description, while leaving all other boxes unmodified. The original sample entry type, which is based on the video codec used for encoding the stream, is then stored within an OriginalFormatBox within the RestrictedSchemelnfoBox. The RestrictedSchemelnfoBox contains three boxes: OriginalFormatBox, SchemeTypeBox, and SchemelnformationBox. The OriginalFormatBoxstores the original sample entry type, which is based on the video codec used for encoding the component stream. The nature of the restriction is defined in the SchemeTypeBox.Overview of the V3C Container File Format.

[0027] FIG. 3 shows the structure of a multi-track ISOBMFF V3C container as defined by the MPEG-I Part 10 (ISO / IEC 23090-10) standard. The boxes in the figure map correspond to the ISOBMFF boxes in ISO / IEC 14496-12. Based on this structure, a multi-track V3C ISOBMFF container includes the following:• A V3C track which contains a V3C parameter set and atlas parameter sets (in the sample entry) and samples carrying atlas sub-bitstream NAL units. This track also includes track references to other tracks carrying the payloads of video compressed V3C units (e.g., unit types V3C_OVD, V3C_GVD, and V3C_AVD).• A restricted video scheme track where the samples contain access units of a video-coded elementary stream for occupancy map data (e.g., payloads of V3C units of type V3C_OVD).• One or more restricted video scheme tracks where the samples contain access units of video-coded elementary streams for geometry data (e.g., payloads of V3C units of type V3C_GVD).• Zero or more restricted video scheme tracks where the samples contain access units of video-coded elementary streams for attribute data (e.g., payloads of V3C units of type V3C_AVD).

[0028] The mechanism of “restricted video track” is used to store the V3C bitstream indicating that a process to be implemented by the receiver on the corresponding track.Issues addressed in some embodiments.

[0029] The V3C codec specification (ISO / IEC 23090-5) specifies the syntax and semantics of V3C sample stream format and NAL sample stream format. The V3C carriage specification (ISO / IEC 23090-10) specifies the storage of system stream NAL unit (SSNU) header size precision information and system stream V3C unit (SSVU) header size precision information in V3CDecoderConfigurationRecord. The specification assumes that this data is not changing over time in the V3C bitstream.

[0030] The V3C codec specification (ISO / IEC 23005) specifies the syntax and semantics of a sample stream format specified for use by applications that deliver some or all of the V3C unit stream as an ordered stream of bytes or bits.

[0031] The V3C sample stream format starts with a sample stream header that is followed by a sequence of sample stream V3C unit syntax structures. Each sample stream V3C unit syntax structure contains an element, named ssvu_v3c_unit_size, that specifies a size, followed by a v3c_unit( ssvu_v3c_unit_size ) syntax structure. This v3c_unit is essentially of size ssvu_v3c_unit_size. The number of bits used to encode the element ssvu_v3c_unit_size is specified in the sample stream header. A sample stream V3C header syntax is shown as follows: i

[0032] A sample stream V3C unit syntax is shown as follows:

[0033] The syntax elements shown above may have the following semantics: ssvh_unit_size_precision_bytes_minus1 plus 1 specifies the precision, in bytes, of the ssvu_v3c_unit_size element in all sample stream V3C units. ssvh_unit_size_precision_bytes_minus1 shall be in the range of 0 to 7. ssvu_v3c_unit_size specifies the size, in bytes, of the subsequent v3c_unit. The number of bits used to represent ssvu_v3c_unit_size is equal to ( ssvh_unit_size_precision_bytes_minus1 + 1 ) * 8.

[0034] The V3C codec specification (ISO / IEC 23005) specifies syntax and semantics of a sample stream format specified for use by applications that deliver some or all of the atlas NAL unit stream as an ordered stream of bytes or bits.

[0035] The NAL unit sample stream format starts with a sample stream header and followed by a sequence of sample stream NAL unit syntax structures. Each sample stream NAL unit syntax structure contains an element, named ssnu_nal_unit_size, that specifies a size, followed by a nal_unit( ssnu_nal_unit_size ) syntax structure. This nal_unit is essentially of size ssnu_nal_unit_size. The number of bits used to encode the element ssnu_nal_unit_size is specified in the sample stream header. A sample stream NAL header syntax is shown as follows:

[0036] A sample stream NAL unit syntax is shown as follows:

[0037] The syntax elements shown above may have the following semantics: ssnh_unit_size_precision_bytes_minus1 plus 1 specifies the precision, in bytes, of the ssnu_nal_unit_size element in all sample stream NAL units. ssnh_unit_size_precision_bytes_minus1 shall be in the range of 0 to 7.The ssnu_nal_unit_size specifies the size, in bytes, of the subsequent NAL_unit. The number of bits used to represent ssnu_nal_unit_size is equal to ( ssnh_unit_size_precision_bytes_minus1 + 1 ) * 8.

[0038] Currently, the existing specification does not discuss how to store the system stream NAL unit header size precision bytes minus one information orthe system stream V3C unit header size precision bytes minus one information when they are changing over time in the V3C bitstream. Some embodiments of this disclosure aim to address this shortcoming. Example embodiments provide details on how to store the system stream NALA / 3C unit header size precision bytes information in an ISOBMFF file when it is changing over time. Example embodiments further describe an association between each sample present in a track and its associated system stream NALA / 3C unit header size precision bytes information.Overview of some example embodiments.

[0039] The present disclosure provides systems and methods for storage of the system stream NALA / 3C unit header size precision information when this information is dynamically changing over time in the V3C bitstream. Example embodiments further provide systems and methods relating to providing a mapping between a sample and its associated NAL / V3C unit header size precision information, e.g. in an ISOBMFF file.

[0040] In some embodiments, a V3C sample stream Unit header (SSUH) information sample group with a grouping_type equal to 'vsuh' is defined in V3C atlas track, V3C atlas tile track or the V3C bit stream track.

[0041] In some embodiments, a SampleGroupDecsriptionEntry with type equal to 'vsuh' is defined in V3C atlas track, V3C atlas tile track or V3C bitstream track to store the dynamically changing NAL or V3C unit header size precision bytes information.

[0042] In some embodiments, mapping is performed of a sample and its associated NAL or V3C unit header size precision bytes information present in a V3C atlas track, V3C atlas tile track or V3C bitstream track using SampleToGroupBox

[0043] Some embodiments allow multiple instances of SampleEntry in a V3C bitstream track, atlas track or atlas tile track to store the dynamically changing system stream V3C or NAL unit header size precision bytes information.Example signaling of dynamic precision information.

[0044] In an example embodiment, when the V3C data is carried using single track and the SSVU header size precision information is changing over time, the SSVU header size precision bytes information related to the samples present in that V3C bitstream track is signaled using a V3C SSUH information sample group with a grouping_type equal to 'vsuh'.

[0045] In an example embodiment, when the V3C data is carried using multiple tracks, and the SSNU header size precision information is changing over time, the SSNU header size precision bytes information related to the samples present in that atlas track or the atlas tile track is signaled using the V3C SSUH information sample group with a grouping_type equal to 'vsuh'.

[0046] In some embodiments, the V3C SSUH information sample group with grouping type 'vsuh' is used to group the V3C atlas samples that use the same SSNU header size precision bytes information in a V3C atlas track or V3C atlas tile track.

[0047] In some embodiments, the V3C SSUH information sample group with grouping type 'vsuh' is used to group the V3C bitstream samples that use the same SSVU header size precision bytes information in a V3C bitstream track.

[0048] The use of 'vsuh' for the grouping_type in sample grouping represents the assignment of samples in a V3C track to the corresponding SSNU or SSVU header size precision bytes information carried in the SampleGroupDescriptionEntryBox. When a SampleToGroupBox with grouping_type equal to 'vsuh' is present, an accompanying SampleGroupDescriptionBox with the same grouping type shall be present and SampleToGroupBox contains the index of the sample group description entry that the sample belongs to.

[0049] In an example embodiment, the grouping type ‘vsuh’ may have the following characteristics:Group Types: ' vsuh 'Container: Sample Group Description Box ( ' sgpd ' ) Mandatory: No Quantity: Zero or one

[0050] In an example embodiment, a V3C sample stream unit header (SSUH) information sample group entry defines the NAL unit header size precision information for all the atlas samples that use the same precision bytes information. A V3C SSUH information sample group entry defines the V3C unit header size precision information for all the V3C bitstream samples in a V3C bitstream track that use the same precision bytes information.

[0051] In some embodiments, sample grouping type 'vsuh' may only be used with tracks with the sample entries 'v3e1', 'v3eg', 'v3c1', 'v3cg', 'v3cb', 'v3t1','v3a1' or 'v3ag'. This sample group and the sample group description entries may be absent from V3C video component tracks. This sample group and the associated sample group description entries may be present in a V3C atlas track or V3C atlas tile track when the SSNU header size precision information changes over time. This sample group and the associated sample group description entries may be present in a V3C bitstream track when the SSVU header size precision information changes over time. When the sample stream NAL unit header precision size or the sample stream V3C unit header precision size is not changing over time, this information may be present in V3CDecoderConfigurationRecord and this sample group and the associated sample group description entries may be absent in any V3C track.

[0052] In some embodiments, the ‘vsuh’ sample grouping type has the following syntax: aligned ( 8 ) clas s V3CSSUHeaderSizePrecis ionInf oEntry ( ) extends VolumetricVi sualSampleGroupEntry ( ' vsuh ' ) { unsigned int ( 3 ) unit size precision bytes minus l ; unsigned int ( 5 ) reserved = 0 ;}

[0053] In some embodiments, the value unit_size_precision_bytes_minus1 plus 1 specifies the precision, in bytes, of the sample stream NAL unit size. In V3C atlas tracks or V3C atlas tile tracks, unit_size_precision_bytes_minus1 may be constrained to be equal to ssnh_unit_size_precision_bytes_minus1 in sample_stream_nal_header(). For V3C bitstream tracks, unit_size_precision_bytes_minus1 may be constrained to be equal to ssvh_unit_size_precision_bytes_minus1 in sample_stream_v3c_header(). In some embodiments, the bits in the value “reserved” are set to zero.

[0054] FIG. 4 illustrates an example of a V3C ISOBMFF file structure with an atlas track. In this example, T rack 1 is an atlas track containing a sample group description box ‘sgpd’ and a sampleto group box ‘sbgp’. The sample to group box ‘sbgp’ has grouping type ‘vsuh’. The sample group description box with grouping_type equal to ‘vsuh’ present in T rack 1 contains the different entries for SSNU header size precision bytes minus one values used in different samples of that track. The sample to group box with grouping_type equal to ‘vsuh’ contains associated sample group description entry index for each sample present in that track.

[0055] When the SSNU header size precision bytes information changes over time, the new SSNU header size precision bytes value is carried in a sample group description entry. The samples using the new SSNU header size precision bytes value are indicated in the sample to group box with grouping_type equal to ‘vsuh’. In the example shown in FIG. 4, samples from 1 to 100 in track 1 use SSNU header size precision bytes minus one value information from the sample group entry description at index 1 . Samples 101 to 300 use the SSNU header size precision bytes minus one value information from the sample group entry description at index 2 in the sample group description box.

[0056] FIG. 5 illustrates an example of a V3C ISOBMFF file structure with a single track. Track 1 is a V3C bitstream track containing sample group description box ‘sgpd’ and a sample to group box ‘sbgp’ with grouping type ‘vsuh’. The sample group description box with grouping_type equal to ‘vsuh’ present in Track 1 contains the different entries for SSVU header size precision bytes minus one values used in different samples of that track. The sample to group box with grouping_type equal to ‘vsuh’ contains associated sample group description entry index for each sample present in that track.

[0057] When the SSVU header size precision bytes information changes over time, the new SSVU header size precision bytes value is carried in a sample group description entry. The samples using the new SSVU header size precision bytes value are indicated in the sample to group box with grouping_type equal to ‘vsuh’. In the example shown in FIG. 5, samples from 1 to 100 in track 1 use SSVU header size precision bytes minus one value information from sample group entry description at index 1 . Samples 101 to 300 use the SSVU header size precision bytes minus one value information from sample group entry description at index 2 in the sample group description box.

[0058] FIG. 6 illustrates an example of a V3C ISOBMFF file structure with one atlas track and two atlas tile tracks. Track 1 is an atlas track containing sample group description box ‘sgpd’ and sample to group box ‘sbgp’ with grouping type equal to ‘vsuh’. The sample group description box with grouping_type equal to ‘vsuh’ present in Track 1 contains the different entries for SSNU header size precision bytes minus one values used in different samples of that track. The sample to group box with grouping_type equal to ‘vsuh’ contains an associated sample group description entry index for each sample present in that track. Similarly Track 2 and Track 3 (the atlas tile tracks) also contain the sample group description box and sample to group box with grouping type equal to ‘vsuh’.

[0059] When the SSNU header size precision bytes information changes over time, the new SSNU header size precision bytes value is carried in a sample group description entry and the samples using the new SSNU header size precision bytes value are indicated in the sample to group box with grouping_type equal to ‘vsuh’. In the example shown in FIG. 6, samples from 1 to 100 in Track 1 use SSNU header size precision bytes minus one value information from the sample group entry description at index 1. Samples 101 to 300 use the SSNU header size precision bytes minus one value information from sample group entry description at index 2 present in the sample group description box. Similarly, samples from 1 to 200 in Track 2 and Track 3 use SSNU header size precision bytes minus one value information from sample group entry description at index 1 . Samples 201 to 300 use the SSNU header size precision bytes minus one value from sample group entry description at index 2.

[0060] With reference to FIG. 6, an example point cloud encoding method comprises encoding, in a container file (such as an ISOBMFF file), at least a first track 602 comprising a plurality of samples including point cloud information. A first sample group description box 604 associated with the first track is encoded in the container file. The first sample group description box includes at least a first sample group description entry 606 and a second sample group description entry 608. Some embodiments may include more such sample group description entries. The first sample group description entry stores first unit header size precision information and the second sample group description entry stores second unit header size precision information different from the first unit header size precision information. A first sample-to-group box 610 is also encoded in the container file. The first sample-to-group box associates a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

[0061] Some embodiments further include encoding, in the container file, at least a second track 612 comprising a plurality of samples including point cloud information, A second sample group description box 614 associated with the second track is also encoded in the container file. The second sample group description box includes at least a third sample group description entry 616 and a fourth sample group description entry 618. The third sample group description entry stores third unit header size precision information and the fourth sample group description entry stores fourth unit header size precision information different from the third unit header size precision information. A second sample-to-group box 620 is also encoded in the container file. The second sample-to-group box associates a third plurality of the samples with the third sample group description entry and the fourth plurality of samples with the fourth sample group description entry. As seen in FIG. 6, additional tracks (e.g. “Track 3”) with additional unit header size precision information may also be provide in some embodiments.

[0062] In other embodiments, when the V3C data is carried using single track and the SSVU header size precision information changes over time, this information may be stored usingmultiple sample entries. An SSVU header size precision information associated to a group of samples in that V3C bitstream track is stored inside the V3CConfigurationBox of a sample entry instance. When the V3C data is carried using multiple tracks and the SSNU header size precision information is changing over time, this information may be stored using multiple sample entries. An SSNU header size precision information associated to a group of samples in that V3C atlas track is stored inside the V3CConfigurationBox of a sample entry instance. An SSNU header size precision information associated to a group of samples in that V3C atlas tile track is stored inside the V3CAtlasTileConfigurationBox of a sample entry instance.Example system hardware.

[0063] Example embodiments of encoders and / or decoders (collectively coders) configured to implement embodiments described herein may be implemented using systems such as the system of FIG. 7. FIG. 7 is a block diagram of an example of a system in which various aspects and embodiments are implemented. System 1000 can be embodied as a device including the various components described below and is configured to perform one or more of the aspects described in this document. Examples of such devices, include, but are not limited to, various electronic devices such as personal computers, laptop computers, smartphones, tablet computers, digital multimedia set top boxes, digital television receivers, personal video recording systems, connected home appliances, and servers. Elements of system 1000, singly or in combination, can be embodied in a single integrated circuit (IC), multiple ICs, and / or discrete components. For example, in at least one embodiment, the processing and encoder / decoder elements of system 1000 are distributed across multiple ICs and / or discrete components. In various embodiments, the system 1000 is communicatively coupled to one or more other systems, or other electronic devices, via, for example, a communications bus or through dedicated input and / or output ports. In various embodiments, the system 1000 is configured to implement one or more of the aspects described in this document.

[0064] The system 1000 includes at least one processor 1010 configured to execute instructions loaded therein for implementing, for example, the various aspects described in this document. Processor 1010 can include embedded memory, input output interface, and various other circuitries as known in the art. The system 1000 includes at least one memory 1020 (e.g., a volatile memory device, and / or a non-volatile memory device). System 1000 includes a storage device 1040, which can include non-volatile memory and / or volatile memory, including, but not limited to, Electrically Erasable Programmable Read-Only Memory (EEPROM), Read-Only Memory (ROM), Programmable Read-Only Memory (PROM), Random Access Memory (RAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), flash, magnetic disk drive, and / or optical disk drive. The storage device 1040 can include an internalstorage device, an attached storage device (including detachable and non-detachable storage devices), and / or a network accessible storage device, as non-limiting examples.

[0065] System 1000 includes an encoder / decoder module 1030 configured, for example, to process data to provide an encoded or decoded point cloud, and the encoder / decoder module 1030 can include its own processor and memory. The encoder / decoder module 1030 represents module(s) that can be included in a device to perform the encoding and / or decoding functions. As is known, a device can include one or both of the encoding and decoding modules. Additionally, encoder / decoder module 1030 can be implemented as a separate element of system 1000 or can be incorporated within processor 1010 as a combination of hardware and software as known to those skilled in the art.

[0066] Program code to be loaded onto processor 1010 or encoder / decoder 1030 to perform the various aspects described in this document can be stored in storage device 1040 and subsequently loaded onto memory 1020 for execution by processor 1010. In accordance with various embodiments, one or more of processor 1010, memory 1020, storage device 1040, and encoder / decoder module 1030 can store one or more of various items during the performance of the processes described in this document. Such stored items can include, but are not limited to, an input point cloud, the decoded point cloud or portions of the decoded point cloud, the bitstream, matrices, variables, and intermediate or final results from the processing of equations, formulas, operations, and operational logic.

[0067] In some embodiments, memory inside of the processor 1010 and / or the encoder / decoder module 1030 is used to store instructions and to provide working memory for processing that is needed during encoding or decoding. In other embodiments, however, a memory external to the processing device (for example, the processing device can be either the processor 1010 or the encoder / decoder module 1030) is used for one or more of these functions. The external memory can be the memory 1020 and / or the storage device 1040, for example, a dynamic volatile memory and / or a non-volatile flash memory. In several embodiments, an external non-volatile flash memory is used to store the operating system of, for example, a television. In at least one embodiment, a fast external dynamic volatile memory such as a RAM is used as working memory for video coding and decoding operations, such as for MPEG-2 (MPEG refers to the Moving Picture Experts Group, MPEG-2 is also referred to as ISO / IEC 13818, and 13818- 1 is also known as H.222, and 13818-2 is also known as H.262), HEVC (HEVC refers to High Efficiency Video Coding, also known as H.265 and MPEG-H Part 2), or WC (Versatile Video Coding, a new standard being developed by JVET, the Joint Video Experts Team).

[0068] The input to the elements of system 1000 can be provided through various input devices as indicated in block 1130. Such input devices include, but are not limited to, (i) a radio frequency (RF) portion that receives an RF signal transmitted, for example, over the air by a broadcaster,(ii) a Component (COMP) input terminal (or a set of COMP input terminals), (iii) a Universal Serial Bus (USB) input terminal, and / or (iv) a High Definition Multimedia Interface (HDMI) input terminal.

[0069] In various embodiments, the input devices of block 1130 have associated respective input processing elements as known in the art. For example, the RF portion can be associated with elements suitable for (i) selecting a desired frequency (also referred to as selecting a signal, or band-limiting a signal to a band of frequencies), (ii) downconverting the selected signal, (iii) band-limiting again to a narrower band of frequencies to select (for example) a signal frequency band which can be referred to as a channel in certain embodiments, (iv) demodulating the downconverted and band-limited signal, (v) performing error correction, and (vi) demultiplexing to select the desired stream of data packets. The RF portion of various embodiments includes one or more elements to perform these functions, for example, frequency selectors, signal selectors, band-limiters, channel selectors, filters, downconverters, demodulators, error correctors, and demultiplexers. The RF portion can include a tuner that performs various of these functions, including, for example, downconverting the received signal to a lower frequency (for example, an intermediate frequency or a near-baseband frequency) or to baseband. In one set-top box embodiment, the RF portion and its associated input processing element receives an RF signal transmitted over a wired (for example, cable) medium, and performs frequency selection by filtering, downconverting, and filtering again to a desired frequency band. Various embodiments rearrange the order of the above-described (and other) elements, remove some of these elements, and / or add other elements performing similar or different functions. Adding elements can include inserting elements in between existing elements, such as, for example, inserting amplifiers and an analog-to-digital converter. In various embodiments, the RF portion includes an antenna.

[0070] Additionally, the USB and / or HDMI terminals can include respective interface processors for connecting system 1000 to other electronic devices across USB and / or HDMI connections. It is to be understood that various aspects of input processing, for example, Reed-Solomon error correction, can be implemented, for example, within a separate input processing IC or within processor 1010 as necessary. Similarly, aspects of USB or HDMI interface processing can be implemented within separate interface ICs or within processor 1010 as necessary. The demodulated, error corrected, and demultiplexed stream is provided to various processing elements, including, for example, processor 1010, and encoder / decoder 1030 operating in combination with the memory and storage elements to process the datastream as necessary for presentation on an output device.

[0071] Various elements of system 1000 can be provided within an integrated housing, Within the integrated housing, the various elements can be interconnected and transmit data therebetween using suitable connection arrangement 1140, for example, an internal bus as known in the art, including the Inter-IC (I2C) bus, wiring, and printed circuit boards.

[0072] The system 1000 includes communication interface 1050 that enables communication with other devices via communication channel 1060. The communication interface 1050 can include, but is not limited to, a transceiver configured to transmit and to receive data over communication channel 1060. The communication interface 1050 can include, but is not limited to, a modem or network card and the communication channel 1060 can be implemented, for example, within a wired and / or a wireless medium.

[0073] Data is streamed, or otherwise provided, to the system 1000, in various embodiments, using a wireless network such as a Wi-Fi network, for example IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signal of these embodiments is received over the communications channel 1060 and the communications interface 1050 which are adapted for Wi-Fi communications. The communications channel 1060 of these embodiments is typically connected to an access point or router that provides access to external networks including the Internet for allowing streaming applications and other over-the-top communications. Other embodiments provide streamed data to the system 1000 using a set-top box that delivers the data over the HDMI connection of the input block 1130. Still other embodiments provide streamed data to the system 1000 using the RF connection of the input block 1130. As indicated above, various embodiments provide data in a non-streaming manner. Additionally, various embodiments use wireless networks other than Wi-Fi, for example a cellular network or a Bluetooth network.

[0074] The system 1000 can provide an output signal to various output devices, including a display 1100, speakers 1110, and other peripheral devices 1120. The display 1100 of various embodiments includes one or more of, for example, a touchscreen display, an organic lightemitting diode (OLED) display, a curved display, and / or a foldable display. The display 1100 can be for a television, a tablet, a laptop, a cell phone (mobile phone), or other device. The display 1100 can also be integrated with other components (for example, as in a smart phone), or separate (for example, an external monitor for a laptop). The other peripheral devices 1120 include, in various examples of embodiments, one or more of a stand-alone digital video disc (or digital versatile disc) (DVR, for both terms), a disk player, a stereo system, and / or a lighting system. Various embodiments use one or more peripheral devices 1120 that provide a function based on the output of the system 1000. For example, a disk player performs the function of playing the output of the system 1000.

[0075] In various embodiments, control signals are communicated between the system 1000 and the display 1100, speakers 1110, or other peripheral devices 1120 using signaling such as AV.Link, Consumer Electronics Control (CEC), or other communications protocols that enable device-to-device control with or without user intervention. The output devices can be communicatively coupled to system 1000 via dedicated connections through respective interfaces 1070, 1080, and 1090. Alternatively, the output devices can be connected to system 1000 usingthe communications channel 1060 via the communications interface 1050. The display 1100 and speakers 1110 can be integrated in a single unit with the other components of system 1000 in an electronic device such as, for example, a television. In various embodiments, the display interface 1070 includes a display driver, such as, for example, a timing controller (T Con) chip.

[0076] The display 1100 and speaker 1110 can alternatively be separate from one or more of the other components, for example, if the RF portion of input 1130 is part of a separate set-top box. In various embodiments in which the display 1100 and speakers 1110 are external components, the output signal can be provided via dedicated output connections, including, for example, HDMI ports, USB ports, or COMP outputs.

[0077] The embodiments can be carried out by computer software implemented by the processor 1010 or by hardware, or by a combination of hardware and software. As a non-limiting example, the embodiments can be implemented by one or more integrated circuits. The memory 1020 can be of any type appropriate to the technical environment and can be implemented using any appropriate data storage technology, such as optical memory devices, magnetic memory devices, semiconductor-based memory devices, fixed memory, and removable memory, as nonlimiting examples. The processor 1010 can be of any type appropriate to the technical environment, and can encompass one or more of microprocessors, general purpose computers, special purpose computers, and processors based on a multi-core architecture, as non-limiting examples.Additional embodiments.

[0078] An example point cloud encoding method comprises: encoding, in a container file (such as an ISOBMFF file), at least a first track comprising a plurality of samples including point cloud information; encoding, in the container file, a first sample group description box associated with the first track, the first sample group description box including at least a first sample group description entry and a second sample group description entry; wherein the first sample group description entry stores first unit header size precision information and the second sample group description entry stores second unit header size precision information different from the first unit header size precision information; and encoding, in the container file, a first sample-to-group box associating a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

[0079] The first track may be, for example, an atlas track, a V3C bitstream track, or an atlas tile track.

[0080] In some embodiments, the unit header size precision information is system stream network abstraction layer (NAL) unit header size precision information.

[0081] In some embodiments, the unit header size precision information is system stream V3C unit header size precision information.

[0082] Some embodiments further include: encoding, in the container file, at least a second track comprising a plurality of samples including point cloud information; encoding, in the container file, a second sample group description box associated with the second track, the second sample group description box including at least a third sample group description entry and a fourth sample group description entry; wherein the third sample group description entry stores third unit header size precision information and the fourth sample group description entry stores fourth unit header size precision information different from the third unit header size precision information; and encoding, in the container file, a second sample-to-group box associating a third plurality of the samples with the third sample group description entry and the fourth plurality of samples with the fourth sample group description entry.

[0083] A decoding method according to some embodiments includes: decoding, from a container file, at least a first track comprising a plurality of samples including point cloud information; decoding, from the container file, a first sample group description box associated with the first track, the first sample group description box including at least a first sample group description entry and a second sample group description entry; wherein the first sample group description entry stores first unit header size precision information and the second sample group description entry stores second unit header size precision information different from the first unit header size precision information; and decoding, from the container file, a first sample-to-group box associating a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

[0084] Example embodiments further include the following: corresponding decoding techniques, apparatus comprising one or more processors configured to perform the methods herein, apparatus comprising at least one processor and a computer-readable medium storing instructions for performing the methods described herein, a computer-readable medium storing a point cloud encoded according to the methods herein, and a signal conveying a point cloud encoded according to the methods herein.

[0085] Note that various hardware elements of one or more of the described embodiments are referred to as “modules” that carry out (i.e., perform, execute, and the like) various functions that are described herein in connection with the respective modules. As used herein, a module includes hardware (e.g., one or more processors, one or more microprocessors, one or more microcontrollers, one or more microchips, one or more application-specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more memory devices) deemed suitable by those of skill in the relevant art for a given implementation. Each described module may also include instructions executable for carrying out the one or more functions described as being carried out by the respective module, and it is noted that those instructions could take the form of or include hardware (i.e., hardwired) instructions, firmware instructions,software instructions, and / or the like, and may be stored in any suitable non-transitory computer- readable medium or media, such as commonly referred to as RAM, ROM, etc.

[0086] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer- readable medium for execution by a computer or processor. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such asCD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

CLAIMS1. An encoding method comprising: encoding, in a container file, at least a first track comprising a plurality of samples including point cloud information; encoding, in the container file, a first sample group description box associated with the first track, the first sample group description box including at least a first sample group description entry and a second sample group description entry; wherein the first sample group description entry stores first unit header size precision information and the second sample group description entry stores second unit header size precision information different from the first unit header size precision information; and encoding, in the container file, a first sample-to-group box associating a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

2. An encoding apparatus comprising one or more processors configured to perform at least: encoding, in a container file, at least a first track comprising a plurality of samples including point cloud information; encoding, in the container file, a first sample group description box associated with the first track, the first sample group description box including at least a first sample group description entry and a second sample group description entry; wherein the first sample group description entry stores first unit header size precision information and the second sample group description entry stores second unit header size precision information different from the first unit header size precision information; and encoding, in the container file, a first sample-to-group box associating a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

3. The method of claim 1 or the apparatus of claim 2, wherein the first track is an atlas track, a V3C bitstream track, or an atlas tile track.

4. The method of claim 1 or claim 3 as it depends from claim 1 , or the apparatus of claim 2 or claim 3 as it depends from claim 2, wherein unit header size precision information is system stream network abstraction layer (NAL) unit header size precision information.

5. The method of claim 1 or claim 3 as it depends from claim 1 , or the apparatus of claim 2 or claim 3 as it depends from claim 2, wherein unit header size precision information is system stream V3C unit header size precision information.

6. The method of claim 1 or claims 3-5 as they depend from claim 1 , or the apparatus of claim 2 or claims 3-5 as they depend from claim 2, further comprising: encoding, in the container file, at least a second track comprising a plurality of samples including point cloud information; encoding, in the container file, a second sample group description box associated with the second track, the second sample group description box including at least a third sample group description entry and a fourth sample group description entry; wherein the third sample group description entry stores third unit header size precision information and the fourth sample group description entry stores fourth unit header size precision information different from the third unit header size precision information; and encoding, in the container file, a second sample-to-group box associating a third plurality of the samples with the third sample group description entry and the fourth plurality of samples with the fourth sample group description entry.

7. The method of claim 1 or claims 3-6 as they depend from claim 1 , or the apparatus of claim 2 or claims 3-6 as they depend from claim 2, wherein the container file is an ISOBMFF file.

8. A decoding method comprising: decoding, from a container file, at least a first track comprising a plurality of samples including point cloud information; decoding, from the container file, a first sample group description box associated with the first track, the first sample group description box including at least a first sample group description entry and a second sample group description entry; wherein the first sample group description entry provides first unit header size precision information and the second sample group description entry provides second unit header size precision information different from the first unit header size precision information; and decoding, from the container file, a first sample-to-group box associating a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

9. A decoding apparatus comprising one or more processors configured to perform at least: decoding, from a container file, at least a first track comprising a plurality of samples including point cloud information; decoding, from the container file, a first sample group description box associated with the first track, the first sample group description box including at least a first sample group description entry and a second sample group description entry;wherein the first sample group description entry provides first unit header size precision information and the second sample group description entry provides second unit header size precision information different from the first unit header size precision information; and decoding, from the container file, a first sample-to-group box associating a first plurality of the samples with the first sample group description entry and the second plurality of samples with the second sample group description entry.

10. The method of claim 8 or the apparatus of claim 9, further comprising processing the point cloud information based on the unit header size precision information.11 . The method of claim 8, or claim 10 as it depends from claim 8, or the apparatus of claim 9, or claim 10 as it depends from claim 9, wherein the first track is an atlas track, a V3C bitstream track, or an atlas tile track.

12. The method of claim 8, or claims 10-11 as they depend from claim 8, or the apparatus of claim 9, or claims 10-11 as they depend from claim 9, wherein unit header size precision information is system stream network abstraction layer (NAL) unit header size precision information.

13. The method of claim 8, or claims 10-11 as they depend from claim 8, or the apparatus of claim 9, or claims 10-11 as they depend from claim 9, wherein unit header size precision information is system stream V3C unit header size precision information.

14. The method of claim 8, or claims 10-13 as they depend from claim 8, or the apparatus of claim 9, or claims 10-13 as they depend from claim 9, further comprising: decoding, from the container file, at least a second track comprising a plurality of samples including point cloud information; decoding, from the container file, a second sample group description box associated with the second track, the second sample group description box including at least a third sample group description entry and a fourth sample group description entry; wherein the third sample group description entry stores third unit header size precision information and the fourth sample group description entry stores fourth unit header size precision information different from the third unit header size precision information; and decoding, from the container file, a second sample-to-group box associating a third plurality of the samples with the third sample group description entry and the fourth plurality of samples with the fourth sample group description entry.

15. The method of claim 8, or claims 10-14 as they depend from claim 8, or the apparatus of claim9, or claims 10-14 as they depend from claim 9, wherein the container file is an ISOBMFF file.

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