SCALABILITY DIMENSION INFORMATION IN VIDEO CODING

A method of processing video data includes using a scalability dimension information (SDI) supplemental enhancement information (SEI) message to indicate an SDI view identifier length minus L syntax element; and converting between a video media file and the bitstream based on the SDI SEI message. A corresponding video coding apparatus and non-transitory computer readable medium are also disclosed.

TECHNICAL FIELD

The present disclosure is generally related to video coding and, in particular, to supplemental enhancement information (SEI) messages used in image/video coding.

BACKGROUND

SUMMARY

The disclosed aspects/embodiments provide techniques that use a scalability dimension information (SDI) view identifier length minus L syntax element to prevent a length of an SDI view ID value syntax element, which specifies a view identifier of an i-th layer in a bitstream, from being zero. The disclosed aspects/embodiments further provide techniques that prevent a bitstream from having a multiview acquisition information supplemental enhancement information (SEI) message or an auxiliary information SEI message when an SDI message is not present in the bitstream. The disclosed aspects/embodiments also provide techniques that prevent the multiview acquisition information SEI message from being scalable-nested.

A first aspect relates to a method of processing video data. The method includes using a scalability dimension information (SDI) supplemental enhancement information (SEI) message to indicate an SDI view identifier length minus L syntax element; and performing a conversion between a video media file and the bitstream based on the SDI SEI message.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the SDI view identifier length minus L syntax element is configured to prevent a length of an SDI view identifier value syntax element, which specifies a view identifier of an i-th layer in a bitstream, from being zero.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that L is equal to 1.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the SDI view identifier length minus L syntax element is designated sdi_view_id_len_minus1.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the SDI view identifier value syntax element is designated sdi_view_id_val[i].

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the SDI view identifier length minus L syntax element, plus one, specifies the length of the SDI view identifier value syntax element.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the SDI view identifier length minus L syntax element is coded as an unsigned integer using N bits.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that N is equal to 4.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the SDI view identifier length minus L syntax element is coded as a fixed-pattern bitstring using N bits, a signed integer using N bits, a truncated binary, a signed integer K-th order Exp-Golomb-coded syntax element where K is equal to 0, or an unsigned integer M-th order Exp-Golomb-coded syntax element where M is equal to 0.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the bitstream is a bitstream in scope.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that a multiview information SEI message and an auxiliary information SEI message are not present in a coded video sequence (CVS) unless the SDI SEI message is present in the CVS.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the multiview information SEI message comprises a multiview acquisition information SEI message.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the auxiliary information SEI message comprises a depth representation information SEI message.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the auxiliary information SEI message comprises an alpha channel information SEI message.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that one or more of an SDI multiview information flag and an SDI auxiliary information flag are equal to 1 when the multiview information SEI message or the auxiliary information SEI message are present in the bitstream.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that the multiview information SEI message comprises a multiview acquisition information SEI message, and wherein the multiview acquisition information SEI message is not scalable-nested.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that an SEI message in the bitstream and having a payload type equal to 179 is constrained from being included in a scalable nesting SEI message.

Optionally, in any of the preceding aspects, another implementation of the aspect provides that an SEI message in the bitstream and having a payload type equal to 3, 133, 179, 180, or 205 is constrained from being included in a scalable nesting SEI message.

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: use a scalability dimension information (SDI) supplemental enhancement information (SEI) message to indicate an SDI view identifier length minus L syntax element; and convert between a video media file and the bitstream based on the SDI SEI message.

A third aspect relates to a non-transitory computer readable medium comprising a computer program product for use by a coding apparatus, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium that, when executed by one or more processors, cause the coding apparatus to: use a scalability dimension information (SDI) supplemental enhancement information (SEI) message to indicate an SDI view identifier length minus L syntax element; and convert between a video media file and the bitstream based on the SDI SEI message.

A fourth aspect relates to a non-transitory computer-readable storage medium storing instructions that cause a processor to: use a scalability dimension information (SDI) supplemental enhancement information (SEI) message to indicate an SDI view identifier length minus L syntax element; and convert between a video media file and the bitstream based on the SDI SEI message.

A fifth 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: use a scalability dimension information (SDI) supplemental enhancement information (SEI) message to indicate an SDI view identifier length minus L syntax element; and convert between a video media file and the bitstream based on the SDI SEI message.

A sixth aspect relates to a method for storing bitstream of a video, comprising: using a scalability dimension information (SDI) supplemental enhancement information (SEI) message to indicate an SDI view identifier length minus L syntax element; generating the bitstream based on the SDI SEI message; and storing the bitstream in a non-transitory computer-readable recording medium.

DETAILED DESCRIPTION

Video coding standards have evolved primarily through the development of the well-known International Telecommunication Union-Telecommunication (ITU-T) and International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) standards. The ITU-T produced H.261 and H.263, ISO/IEC produced Moving Picture Experts Group (MPEG)-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4 Advanced Video Coding (AVC) and H.265/High Efficiency Video Coding (HEVC) standards. See ITU-T and ISO/IEC, “High efficiency video coding”, Rec. ITU-T H.265|ISO/IEC 23008-2 (in force edition). Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized. To explore the future video coding technologies beyond HEVC, the Joint Video Exploration Team (JVET) was founded by Video Coding Experts Group (VCEG) and MPEG jointly in 2015. Since then, many new methods have been adopted by JVET and put into the reference software named Joint Exploration Model (JEM). See J. Chen, E. Alshina, G. J. Sullivan, J.-R. Ohm, J. Boyce, “Algorithm description of Joint Exploration Test Model 7 (JEM7),” JVET-G1001, August 2017. The JVET was later renamed to be the Joint Video Experts Team (JVET) when the Versatile Video Coding (VVC) project officially started. VVC is the new coding standard, targeting at 50% bitrate reduction as compared to HEVC, that has been finalized by the JVET at its 19th meeting ended at Jul. 1, 2020. See Rec. ITU-T H.266|ISO/IEC 23090-3, “Versatile Video Coding”, 2020.

The VVC standard (ITU-T H.266|ISO/IEC 23090-3) and the associated Versatile Supplemental Enhancement Information (VSEI) standard (ITU-T H.274|ISO/IEC 23002-7) have been designed for use in a maximally broad range of applications, including both the traditional uses such as television broadcast, video conferencing, or playback from storage media, and also newer and more advanced use cases such as adaptive bit rate streaming, video region extraction, composition and merging of content from multiple coded video bitstreams, multiview video, scalable layered coding, and viewport-adaptive 360° immersive media. See B. Bross, J. Chen, S. Liu, Y.-K. Wang (editors), “Versatile Video Coding (Draft 10),” JVET-S2001, Rec. ITU-T Rec. H.274|ISO/IEC 23002-7, “Versatile Supplemental Enhancement Information Messages for Coded Video Bitstreams”, 2020, and J. Boyce, V. Drugeon, G. Sullivan, Y.-K. Wang (editors), “Versatile supplemental enhancement information messages for coded video bitstreams (Draft 5),” JVET-S2007.

The Essential Video Coding (EVC) standard (ISO/IEC 23094-1) is another video coding standard that has recently been developed by MPEG.

FIG.1is a schematic diagram illustrating an example of layer based prediction100. Layer based prediction100is compatible with unidirectional inter-prediction and/or bidirectional inter-prediction, but is also performed between pictures in different layers.

Layer based prediction100is applied between pictures111,112,113, and114and pictures115,116,117, and118in different layers. In the example shown, pictures111,112,113, and114are part of layer N+1132and pictures115,116,117, and118are part of layer N131. A layer, such as layer N131and/or layer N+1132, is a group of pictures that are all associated with a similar value of a characteristic, such as a similar size, quality, resolution, signal to noise ratio, capability, etc. In the example shown, layer N+1132is associated with a larger image size than layer N131. Accordingly, pictures111,112,113, and114in layer N+1132have a larger picture size (e.g., larger height and width and hence more samples) than pictures115,116,117, and118in layer N131in this example. However, such pictures can be separated between layer N+1132and layer N131by other characteristics. While only two layers, layer N+1132and layer N131, are shown, a set of pictures can be separated into any number of layers based on associated characteristics. Layer N+1132and layer N131may also be denoted by a layer ID. A layer ID is an item of data that is associated with a picture and denotes the picture is part of an indicated layer. Accordingly, each picture111-118may be associated with a corresponding layer ID to indicate which layer N+1132or layer N131includes the corresponding picture.

Pictures111-118in different layers131-132are configured to be displayed in the alternative. As such, pictures111-118in different layers131-132can share the same temporal identifier (ID) and can be included in the same access unit (AU)106. As used herein, an AU is a set of one or more coded pictures associated with the same display time for output from a decoded picture buffer (DPB). For example, a decoder may decode and display picture115at a current display time if a smaller picture is desired or the decoder may decode and display picture111at the current display time if a larger picture is desired. As such, pictures111-114at higher layer N+1132contain substantially the same image data as corresponding pictures115-118at lower layer N131(notwithstanding the difference in picture size). Specifically, picture111contains substantially the same image data as picture115, picture112contains substantially the same image data as picture116, etc.

Pictures111-118can be coded by reference to other pictures111-118in the same layer N131or N+1132. Coding a picture in reference to another picture in the same layer results in inter-prediction123, which is compatible unidirectional inter-prediction and/or bidirectional inter-prediction. Inter-prediction123is depicted by solid line arrows. For example, picture113may be coded by employing inter-prediction123using one or two of pictures111,112, and/or114in layer N+1132as a reference, where one picture is referenced for unidirectional inter-prediction and/or two pictures are referenced for bidirectional inter-prediction. Further, picture117may be coded by employing inter-prediction123using one or two of pictures115,116, and/or118in layer N131as a reference, where one picture is referenced for unidirectional inter-prediction and/or two pictures are referenced for bidirectional inter-prediction. When a picture is used as a reference for another picture in the same layer when performing inter-prediction123, the picture may be referred to as a reference picture. For example, picture112may be a reference picture used to code picture113according to inter-prediction123. Inter-prediction123can also be referred to as intra-layer prediction in a multi-layer context. As such, inter-prediction123is a mechanism of coding samples of a current picture by reference to indicated samples in a reference picture that are different from the current picture where the reference picture and the current picture are in the same layer.

Pictures111-118can also be coded by reference to other pictures111-118in different layers. This process is known as inter-layer prediction121, and is depicted by dashed arrows. Inter-layer prediction121is a mechanism of coding samples of a current picture by reference to indicated samples in a reference picture where the current picture and the reference picture are in different layers and hence have different layer IDs. For example, a picture in a lower layer N131can be used as a reference picture to code a corresponding picture at a higher layer N+1132. As a specific example, picture111can be coded by reference to picture115according to inter-layer prediction121. In such a case, the picture115is used as an inter-layer reference picture. An inter-layer reference picture is a reference picture used for inter-layer prediction121. In most cases, inter-layer prediction121is constrained such that a current picture, such as picture111, can only use inter-layer reference picture(s) that are included in the same AU106and that are at a lower layer, such as picture115. When multiple layers (e.g., more than two) are available, inter-layer prediction121can encode/decode a current picture based on multiple inter-layer reference picture(s) at lower levels than the current picture.

A video encoder can employ layer based prediction100to encode pictures111-118via many different combinations and/or permutations of inter-prediction123and inter-layer prediction121. For example, picture115may be coded according to intra-prediction. Pictures116-118can then be coded according to inter-prediction123by using picture115as a reference picture. Further, picture111may be coded according to inter-layer prediction121by using picture115as an inter-layer reference picture. Pictures112-114can then be coded according to inter-prediction123by using picture111as a reference picture. As such, a reference picture can serve as both a single layer reference picture and an inter-layer reference picture for different coding mechanisms. By coding higher layer N+1132pictures based on lower layer N131pictures, the higher layer N+1132can avoid employing intra-prediction, which has much lower coding efficiency than inter-prediction123and inter-layer prediction121. As such, the poor coding efficiency of intra-prediction can be limited to the smallest/lowest quality pictures, and hence limited to coding the smallest amount of video data. The pictures used as reference pictures and/or inter-layer reference pictures can be indicated in entries of reference picture list(s) contained in a reference picture list structure.

Each AU106inFIG.1may contain several pictures. For example, one AU106may contain pictures111and115. Another AU106may contain pictures112and116. Indeed, each AU106is a set of one or more coded pictures associated with the same display time (e.g., the same temporal ID) for output from a decoded picture buffer (DPB) (e.g., for display to a user). Each access unit delimiter (AUD)108is an indicator or data structure used to indicate the start of an AU (e.g., AU108) or the boundary between AUs.

Previous H.26x video coding families have provided support for scalability in separate profile(s) from the profile(s) for single-layer coding. Scalable video coding (SVC) is the scalable extension of the AVC/H.264 that provides support for spatial, temporal, and quality scalabilities. For SVC, a flag is signaled in each macroblock (MB) in enhancement layer (EL) pictures to indicate whether the EL MB is predicted using the collocated block from a lower layer. The prediction from the collocated block may include texture, motion vectors, and/or coding modes. Implementations of SVC cannot directly reuse unmodified H.264/AVC implementations in their design. The SVC EL macroblock syntax and decoding process differs from H.264/AVC syntax and decoding process.

Scalable HEVC (SHVC) is the extension of the HEVC/H.265 standard that provides support for spatial and quality scalabilities, multiview HEVC (MV-HEVC) is the extension of the HEVC/H.265 that provides support for multi-view scalability, and 3D HEVC (3D-HEVC) is the extension of the HEVC/H.264 that provides support for three dimensional (3D) video coding that is more advanced and more efficient than MV-HEVC. Note that the temporal scalability is included as an integral part of the single-layer HEVC codec. The design of the multi-layer extension of HEVC employs the idea where the decoded pictures used for inter-layer prediction come only from the same AU and are treated as long-term reference pictures (LTRPs), and are assigned reference indices in the reference picture list(s) along with other temporal reference pictures in the current layer. Inter-layer prediction (ILP) is achieved at the prediction unit (PU) level by setting the value of the reference index to refer to the inter-layer reference picture(s) in the reference picture list(s).

Notably, both reference picture resampling and spatial scalability features call for resampling of a reference picture or part thereof. Reference picture resampling (RPR) can be realized at either the picture level or coding block level. However, when RPR is referred to as a coding feature, it is a feature for single-layer coding. Even so, it is possible or even preferable from a codec design point of view to use the same resampling filter for both the RPR feature of single-layer coding and the spatial scalability feature for multi-layer coding.

FIG.2illustrates an example of layer based prediction200utilizing output layer sets (OLSs). Layer based prediction100is compatible with unidirectional inter-prediction and/or bidirectional inter-prediction, but is also performed between pictures in different layers. The layer based prediction ofFIG.2is similar to that ofFIG.1. Therefore, for the sake of brevity, a full description of layer based prediction is not repeated.

Some of the layers in the coded video sequence (CVS)290ofFIG.2are included in an OLS. An OLS is a set of layers for which one or more layers are specified as the output layers. An output layer is a layer of an OLS that is output.FIG.2depicts three different OLSs, namely OLS1, OLS2, and OLS3. As shown, OLS1includes Layer N231and Layer N+1232. Layer N231includes pictures215,216,217and218, and Layer N+1232includes pictures211,212,213, and214. OLS2includes Layer N231, Layer N+1232, Layer N+2233, and Layer N+3234. Layer N+2233includes pictures241,242,243, and244, and Layer N+3234includes pictures251,252,253, and254. OLS3includes Layer N231, Layer N+1232, and Layer N+2233. Despite three OLSs being shown, a different number of OLSs may be used in practical applications. In the illustrated embodiment, none of the OLSs include Layer N+4235, which contains pictures261,262,263, and264.

Each of the different OLSs may contain any number of layers. The different OLSs are generated in an effort to accommodate the coding capabilities of a variety of different devices having varying coding capabilities. For example, OLS1, which contains only two layers, may be generated to accommodate a mobile phone with relatively limited coding capabilities. On the other hand, OLS2, which contains four layers, may be generated to accommodate a big screen television, which is able to decode higher layers than the mobile phone. OLS3, which contains three layers, may be generated to accommodate a personal computer, laptop computer, or a tablet computer, which may be able to decode higher layers than the mobile phone but cannot decode the highest layers like the big screen television.

The layers inFIG.2can be all independent from each other. That is, each layer can be coded without using inter-layer prediction (ILP). In this case, the layers are referred to as simulcast layers. One or more of the layers inFIG.2may also be coded using ILP. Whether the layers are simulcast layers or whether some of the layers are coded using ILP may be signaled by a flag in a video parameter set (VPS). When some layers use ILP, the layer dependency relationship among layers is also signaled in the VPS.

In an embodiment, when the layers are simulcast layers, only one layer is selected for decoding and output. In an embodiment, when some layers use ILP, all of the layers (e.g., the entire bitstream) are specified to be decoded, and certain layers among the layers are specified to be output layers. The output layer or layers may be, for example, 1) only the highest layer, 2) all the layers, or 3) the highest layer plus a set of indicated lower layers. For example, when the highest layer plus a set of indicated lower layers are designated for output by a flag in the VPS, Layer N+3234(which is the highest layer) and Layers N231and N+1232(which are lower layers) from OLS2are output.

Some layers inFIG.2may be referred to as primary layers, while other layers may be referred to as auxiliary layers. For example, Layer N231and Layer N+1232may be referred to as primary layers, and Layer N+2233and Layer N+3234may be referred to as auxiliary layers. The auxiliary layers may be referred to as an alpha auxiliary layer or a depth auxiliary layer. A primary layer may be associated with an auxiliary layer when auxiliary information is present in the bitstream.

Unfortunately, existing standards have drawbacks.1. Currently, the syntax element sdi_view_id_len is coded as u(4), and the value is required to be in the range of 0 to 15, inclusive. This value specifies the length in bits of the sdi_view_id_val[i] syntax element, specifying the view ID of the i-th layer in the bitstream. However, the length of sdi_view_id_val[i] shall not be equal to 0, while this is currently allowed.2. When some auxiliary information is present in the bitstream, e.g., as indicated by the SDI SEI message (a.k.a., the scalability dimension SEI message), and the depth representation information SEI message or the alpha channel information SEI message, it is unknown which non-auxiliary or primary layers the auxiliary information applies to.3. It does not make sense to have a multiview acquisition information SEI message, depth representation information SEI message, or alpha channel information SEI message present in the bitstream if the scalability dimension information SEI message is not present in the bitstream.4. The multiview acquisition information SEI message contains information for all views present in the bitstream. Therefore, it's meaningless for it to be scalable-nested while this is currently allowed.

Disclosed herein are techniques that solve one or more of the foregoing problems. For example, the present disclosure provides techniques that use a scalability dimension information (SDI) view identifier length minus L syntax element to prevent a length of an SDI view ID value syntax element, which specifies a view identifier of an i-th layer in a bitstream, from being zero. The disclosed aspects/embodiments further provide techniques that prevent a bitstream from having a multiview acquisition information supplemental enhancement information (SEI) message or an auxiliary information SEI message when an SDI message is not present in the bitstream. The disclosed aspects/embodiments also provide techniques that prevent the multiview acquisition information SEI message from being scalable-nested.

FIG.3illustrates an embodiment of a video bitstream300. As used herein the video bitstream300may also be referred to as a coded video bitstream, a bitstream, or variations thereof. As shown inFIG.3, the bitstream300comprises one or more of the following: decoding capability information (DCI)302, a video parameter set (VPS)304, a sequence parameter set (SPS)306, a picture parameter set (PPS)308, a picture header (PH)312, a picture314, and an SEI message322. Each of the DCI302, the VPS304, the SPS306, and the PPS308may be generically referred to as a parameter set. In an embodiment, other parameter sets not shown inFIG.3may also be included in the bitstream300such as, for example, an adaption parameter set (APS), which is a syntax structure containing syntax elements that apply to zero or more slices as determined by zero or more syntax elements found in slice headers.

The DCI302, which may also be referred to a decoding parameter set (DPS) or decoder parameter set, is a syntax structure containing syntax elements that apply to the entire bitstream. The DCI302includes parameters that stay constant for the lifetime of the video bitstream (e.g., bitstream300), which can translate to the lifetime of a session. The DCI302can include profile, level, and sub-profile information to determine a maximum complexity interop point that is guaranteed to be never exceeded, even if splicing of video sequences occurs within a session. It further optionally includes constraint flags, which indicate that the video bitstream will be constraint of the use of certain features as indicated by the values of those flags. With this, a bitstream can be labelled as not using certain tools, which allows among other things for resource allocation in a decoder implementation Like all parameter sets, the DCI302is present when first referenced, and referenced by the very first picture in a video sequence, implying that it has to be sent among the first network abstraction layer (NAL) units in the bitstream. While multiple DCIs302can be in the bitstream, the value of the syntax elements therein cannot be inconsistent when being referenced.

The VPS304includes decoding dependency or information for reference picture set construction of enhancement layers. The VPS304provides an overall perspective or view of a scalable sequence, including what types of operation points are provided, the profile, tier, and level of the operation points, and some other high-level properties of the bitstream that can be used as the basis for session negotiation and content selection, etc.

In an embodiment, when it is indicated that some of the layers use ILP, the VPS304indicates that a total number of OLSs specified by the VPS is equal to the number of layers, indicates that the i-th OLS includes the layers with layer indices from 0 to i, inclusive, and indicates that for each OLS only the highest layer in the OLS is output.

The SPS306contains data that is common to all the pictures in a sequence of pictures (SOP). The SPS306is a syntax structure containing syntax elements that apply to zero or more entire CLVSs as determined by the content of a syntax element found in the PPS referred to by a syntax element found in each picture header. In contrast, the PPS308contains data that is common to the entire picture. The PPS308is a syntax structure containing syntax elements that apply to zero or more entire coded pictures as determined by a syntax element found in each picture header (e.g., PH312).

The DCI302, the VPS304, the SPS306, and the PPS308are contained in different types of Network Abstraction Layer (NAL) units. A NAL unit is a syntax structure containing an indication of the type of data to follow (e.g., coded video data). NAL units are classified into video coding layer (VCL) and non-VCL NAL units. The VCL NAL units contain the data that represents the values of the samples in the video pictures, and the non-VCL NAL units contain any associated additional information such as parameter sets (important data that can apply to a number of VCL NAL units) and supplemental enhancement information (timing information and other supplemental data that may enhance usability of the decoded video signal but are not necessary for decoding the values of the samples in the video pictures).

In an embodiment, the DCI302is contained in a non-VCL NAL unit designated as a DCI NAL unit or a DPS NAL unit. That is, the DCI NAL unit has a DCI NAL unit type (NUT) and the DPS NAL unit has a DPS NUT. In an embodiment, the VPS304is contained in a non-VCL NAL unit designated as a VPS NAL unit. Therefore, the VPS NAL unit has a VPS NUT. In an embodiment, the SPS306is a non-VCL NAL unit designated as a SPS NAL unit. Therefore, the SPS NAL unit has an SPS NUT. In an embodiment, the PPS308is contained in a non-VCL NAL unit designated as a PPS NAL unit. Therefore, the PPS NAL unit has a PPS NUT.

The PH312is a syntax structure containing syntax elements that apply to all slices (e.g., slices318) of a coded picture (e.g., picture314). In an embodiment, the PH312is in a type of non-VCL NAL unit designated a PH NAL unit. Therefore, the PH NAL unit has a PH NUT (e.g., PH_NUT).

In an embodiment, the PH NAL unit associated with the PH312has a temporal ID and a layer ID. The temporal ID identifier indicates the position of the PH NAL unit, in time, relative to the other PH NAL units in the bitstream (e.g., bitstream300). The layer ID indicates the layer (e.g., layer131or layer132) that contains the PH NAL unit. In an embodiment, the temporal ID is similar to, but different from, the picture order count (POC). The POC uniquely identifies each picture in order. In a single layer bitstream, temporal ID and POC would be the same. In a multi-layer bitstream (e.g., seeFIG.1), pictures in the same AU would have different POCs, but the same temporal ID.

In an embodiment, the PH NAL unit precedes the VCL NAL unit containing the first slice318of the associated picture314. This establishes the association between the PH312and the slices318of the picture314associated with the PH312without the need to have a picture header ID signaled in the PH312and referred to from the slice header320. Consequently, it can be inferred that all VCL NAL units between two PHs312belong to the same picture314and that the picture314is associated with the first PH312between the two PHs312. In an embodiment, the first VCL NAL unit that follows a PH312contains the first slice318of the picture314associated with the PH312.

In one alternative, the PH NAL unit follows picture level parameter sets and prefix supplemental enhancement information (SEI) messages, or higher level parameter sets such as the DCI (a.k.a., the DPS), the VPS, the SPS, the PPS, the APS, the SEI message, etc.

The picture314is an array of luma samples in monochrome format or an array of luma samples and two corresponding arrays of chroma samples in 4:2:0, 4:2:2, and 4:4:4 color format.

The picture314may be either a frame or a field. However, in one CVS316, either all pictures314are frames or all pictures314are fields. The CVS316is a coded video sequence for every coded layer video sequence (CLVS) in the video bitstream300. Notably, the CVS316and the CLVS are the same when the video bitstream300includes a single layer. The CVS316and the CLVS are only different when the video bitstream300includes multiple layers (e.g., as shown inFIGS.1and2).

Each picture314contains one or more slices318. A slice318is an integer number of complete tiles or an integer number of consecutive complete coding tree unit (CTU) rows within a tile of a picture (e.g., picture314). Each slice318is exclusively contained in a single NAL unit (e.g., a VCL NAL unit). A tile (not shown) is a rectangular region of CTUs within a particular tile column and a particular tile row in a picture (e.g., picture314). A CTU (not shown) is a coding tree block (CTB) of luma samples, two corresponding CTBs of chroma samples of a picture that has three sample arrays, or a CTB of samples of a monochrome picture or a picture that is coded using three separate color planes and syntax structures used to code the samples. A CTB (not shown) is an N×N block of samples for some value of N such that the division of a component into CTBs is a partitioning. A block (not shown) is an M×N (M-column by N-row) array of samples (e.g., pixels), or an M×N array of transform coefficients.

In an embodiment, each slice318contains a slice header320. A slice header320is the part of the coded slice318containing the data elements pertaining to all tiles or CTU rows within a tile represented in the slice318. That is, the slice header320contains information about the slice318such as, for example, the slice type, which of the reference pictures will be used, and so on.

The pictures314and their slices318comprise data associated with the images or video being encoded or decoded. Thus, the pictures314and their slices318may be simply referred to as the payload or data being carried in the bitstream300.

The bitstream300also contains one or more SEI messages, such as SEI message322, SEI message326, and SEI message328. The SEI messages contain supplemental enhancement information. SEI messages can contain various types of data that indicate the timing of the video pictures or describe various properties of the coded video or how the coded video can be used or enhanced. SEI messages are also defined that can contain arbitrary user-defined data. SEI messages do not affect the core decoding process, but can indicate how the video is recommended to be post-processed or displayed. Some other high-level properties of the video content are conveyed in video usability information (VUI), such as the indication of the color space for interpretation of the video content. As new color spaces have been developed, such as for high dynamic range and wide color gamut video, additional VUI identifiers have been added to indicate them.

In an embodiment, the SEI message322may be an SDI SEI message. The SDI SEI message may be used to indicate which primary layers are associated with an auxiliary layer when auxiliary information is present in a bitstream. For example, the SDI SEI message may include one or more syntax elements324to indicate which primary layers are associated with the auxiliary layer when the auxiliary information is present in the bitstream. A discussion of various SEI messages and the syntax elements included in those SEI messages is provided below.

In an embodiment, the SEI message326is a multiview information SEI message, such as a multiview acquisition information SEI message. When present in the bitstream300, the multiview information SEI message includes one or more syntax elements324that specify various parameters of the acquisition environment, e.g., intrinsic and extrinsic camera parameters. These parameters are useful for view warping and interpolation.

In an embodiment, the SEI message328may be an auxiliary information SEI message, such as a depth representation information SEI message or an alpha channel information SEI message. When present in the bitstream300, the depth representation information SEI message includes one or more syntax elements324that specify various depth representation for depth views for the purpose of processing decoded texture and depth view components prior to rendering on a three dimensional (3D) display, such as view synthesis. The SEI message may be associated with an instantaneous decoder refresh (IDR) access unit for the purpose of random access. When present in the bitstream300, the alpha channel information SEI message includes one or more syntax elements324that provide information about alpha channel sample values and post-processing applied to the decoded alpha plane auxiliary pictures, and one or more associated primary pictures. Blending is the process of combining two images into a single image. An image to be blended is associated with an auxiliary image identified as an alpha plane. The alpha channel information SEI message may be used to specify how the pixel values of the image to be blended are converted to another image comprising interpretation values.

Those skilled in the art will appreciate that the bitstream300may contain other parameters and information in practical applications.

To solve the above problems, methods as summarized below are disclosed. The techniques should be considered as examples to explain the general concepts and should not be interpreted in a narrow way. Furthermore, these techniques can be applied individually or combined in any manner.

1) To solve problem 1, in one example, instead of signaling the length of view ID syntax elements, e.g., via the syntax element sdi_view_id_len, the value of the length minus L (e.g., L=1) is signaled, e.g., via the syntax element sdi_view_id_len_minusL.a. In one example, furthermore, the syntax element may be coded as an unsigned integer using N bits.i. In one example, N may be equal to 4.ii. Alternatively, the syntax may be coded as a fixed-pattern bit string using N bits, or signed integer using N bits, or truncated binary, or a signed integer K-th (e.g., K=0) order Exp-Golomb-coded syntax element, or an unsigned integer M-th (e.g., M=0) order Exp-Golomb-coded syntax element.b. In one example, alternatively, still signal the length, e.g., via the syntax element sdi_view_id_len, but it is constrained that the value of syntax element shall not be equal to 0.

2) To solve problem 2, it is proposed that an auxiliary layer (i.e., a layer having the corresponding sdi_aux_id[i] equal to 1 or 2) may be applied to one or more associated layers.a. In one example, one or more syntax elements indicating the associated layers for each auxiliary layer may be signaled in the scalability dimension information SEI message.i. In one example, the associated layers are specified by layer IDs.ii. In another example, the associated layers are specified by layer indices.iii. In another example, the indication whether the auxiliary layer is applied to one or more associated layers may be specified by one or more syntax elements for the associated layers.1. In one example, a syntax element may be used to indicate whether the auxiliary layer is applied to all the associated layers.2. In one example, a syntax element may be used to indicate whether the auxiliary layer is applied to a specific associated layer.a. In one example, one or more primary layers are indicated by the syntax elements.i. In one example, all the primary layers may be indicated by the syntax elements.ii. In one example, only the primary layers of which the layer index is smaller than the layer index of the auxiliary layer may be indicated by the syntax elements.iii. In one example, only the primary layers of which the layer index is larger than the layer index of the auxiliary layer may be indicated by the syntax elements.b. In one example, the syntax element is coded as a flag.b. Alternatively, it is proposed that the associated one or more layers for each auxiliary layer may be derived without being explicitly signaled.i. In one example, the associated layers for each auxiliary layer may be the layer having nuh_layer_id equal to the nuh_layer_id of the auxiliary layer plus N1, N2, . . . , and Nk, respectively, where k is an integer and Ni !=Nj for any i, j (i !=j) in the range of 1 to k, inclusive.1. In one example, k is equal to 1 and N1 may be equal to 1, or 2, or −1, or −2.2. In one example, k is greater than 1.a. In one example, k is equal to 2 and N1=1, N2=2.ii. In one example, the associated layers for each auxiliary layer may be the layer having layer index equal to the layer index of the auxiliary layer plus N1, N2, . . . , and Nk, respectively, where k is an integer and Ni !=Nj for any i, j (i !=j) in the range of 1 to k, inclusive.1. In one example, k is equal to 1 and N1 may be equal to 1, or 2, or −1, or −2.2. In one example, k is greater than 1.a. In one example, k is equal to 2 and N1=1, N2=2.c. Alternatively, indications of the associated layers of each auxiliary layer may be explicitly signaled as one or a group of syntax elements in the scalability dimension information SEI message.d. Alternatively, indications of the associated layers of an auxiliary information SEI message (e.g., depth representation information or alpha channel information) may be explicitly signaled by one or more syntax elements in the auxiliary information SEI message.i. In one example, the auxiliary information SEI message may refer to the depth representation information SEI message or the alpha channel information SEI message.ii. In one example, the one or more syntax elements may indicate layer ID values of the associated layers.1. In one example, the layer IDs indicated by the syntax elements may be required to be less than or equal to the maximum layer ID value, i.e., vps_layer_id[vps_max_layers_minus1] or vps_layer_id[sdi_max_layers_minus1].iii. In one example, the one or more syntax elements may indicate layer index values of the associated layers.1. In one example, the layer indices indicated by the syntax elements may be required to be less than the maximum number of layers in the bitstream (e.g., sdi_max_layers_minus1 plus 1 or vps_max_layers_minus1 plus 1).iv. In one example, indication of whether one or multiple layers are associated with auxiliary layers may be signaled.1. In one example, one syntax element may be used to specify whether an auxiliary information SEI message applies to all layers.a. In one example, auxiliary_all_layer_flag equal to X (X being 1 or 0) may specify that the auxiliary information SEI message is applied to all associated primary layers.2. In one example, one or more syntax elements may be used to specify whether the auxiliary information SEI message is applied to one or more layers.a. In one example, N syntax element may be used to specify whether the auxiliary information SEI message is applied to N layers, wherein each syntax element is used for each layer.i. In one example, the syntax element may be coded as a flag using 1 bit.b. In one example, one syntax element may be used to specify whether the auxiliary information SEI message is applied to one or more layers.i. In one example, the syntax element may be K-th (e.g., K=0) Exp-Golomb coded.ii. In one example, the syntax element equal to 5 specifies that the auxiliary information SEI message is applied to 0-th and 2nd layer but not applied to 1st layer.1. Alternatively, denote N as the number of the layers. The syntax element equal to 5 specifies that the auxiliary information SEI message is applied to (N−1)-th and (N−3)-nd layer but not applied to (N−2)-th layer.c. The above syntax elements may be conditionally signaled, e.g., only when the auxiliary information SEI message is not applied to all layers,e. In one example, indication of number of associated layers of auxiliary pictures for one layer may be signaled in the bitstream.f. In one example, the above syntax elements may be signaled using unsigned integer using N bits, or, fixed-pattern bit string using N bits, or signed integer using N bits, or truncated binary, or signed integer K-th (e.g., K=0) order Exp-Golomb-coded syntax element, or unsigned integer M-th (e.g., M=0) order Exp-Golomb-coded syntax element.g. In one example, indications of number of associated layers of auxiliary pictures and/or associated layers of auxiliary pictures may be conditionally signaled, e.g., only when the i-th layer in bitstreamInScope contains auxiliary pictures (e.g., sdi_aux_id[i]>0). The bitstreamInScope (a.k.a., bitstream in scope) is defined as a sequence of AUs that consists, in decoding order, of an initial AU containing an SDI SEI message followed by zero or more subsequent AUs up to, but not including, any subsequent AU that contains another SDI SEI message.

3) To solve problem 3, a requirement of bitstream conformance is added that multiview or auxiliary information SEI message shall not be present in a CVS that does not have a scalability dimension information SEI message.a. Furthermore, the multiview information SEI message may refer to the multiview acquisition information SEI message.b. Furthermore, the auxiliary information SEI message may refer to the depth representation information SEI message or the alpha channel information SEI message.c. Alternatively, a requirement of bitstream conformance is added that when the multiview or auxiliary information SEI message is present in the bitstream, at least one of sdi_multiview_info_flag and sdi_auxiliary_info_flag of the scalability dimension information SEI message is required to be equal to 1.

4) To solve problem 4, in one example, a requirement of bitstream conformance is added that the multiview acquisition information SEI message shall not be scalable-nested.a. Alternatively, it is specified that an SEI message that has payloadType equal to 179 (multiview acquisition) shall not be contained in a scalable nesting SEI message.

Below are some example embodiments for some of the examples summarized above. Each embodiment can be applied to VVC. Most relevant parts that have been added or modified are depicted in a bold italic font, and some of the deleted parts are depicted in an italic font. There may be some other changes that are editorial in nature and thus not highlighted.

Each scalability dimension SEI message syntax described below includes one or more syntax elements. A syntax element may be, for example, one or more values, flags, variables, phrases, indications, indices, mappings, data elements, or a combination thereof included in the scalability dimension SEI message syntax disclosed herein. In an embodiment, the syntax elements may be organized into a group of values, flags, variables, phrases, indications, indices, mappings, and/or data elements.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len_minus1 plus 1 specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len_minus1+1 bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len_minus1 plus 1 specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len_minus1+1 bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element. When present, sdi_view_id_len shall not be equal to 0.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.

Alternatively, the following applies:sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element. When present, sdi_view_id_len shall not be equal to 0.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1..

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.sdi_aux_id[i] equal to 0 indicates that the i-th layer in bitstreamInScope does not contain auxiliary pictures. sdi_aux_id[i] greater than 0 indicates the type of auxiliary pictures in the i-th layer in bitstreamInScope as specified in Table 1.

NOTE 1—The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Depth Representation Information SEI Message

Depth Representation Information SEI Message Syntax

Depth Representation Information SEI Message Semantics

When present, the depth representation information SEI message shall be associated with one or more layers with sdi_aux_id value equal to AUX_DEPTH. The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the depth representation information SEI message applies.

When present, the depth representation information SEI message may be included in any access unit. It is recommended that, when present, the SEI message is included for the purpose of random access in an access unit in which the coded picture with nuh_layer_id equal to targetLayerId is an Intra Random Access Picture (IRAP) picture.

For an auxiliary picture with sdi_aux_id[targetLayerId] equal to AUX_DEPTH, an associated primary picture, if any, is a picture in the same access unit having sdi_aux_id[nuhLayerIdB] equal to 0 such that ScalabilityId[LayerIdxInVps[targetLayerId]][j] is equal to ScalabilityId[LayerIdxInVps[nuhLayerIdB]][j] for all values of j in the range of 0 to 2, inclusive, and 4 to 15, inclusive.

The information indicated in the SEI message applies to all the pictures with nuh_layer_id equal to targetLayerId from the access unit containing the SEI message up to but excluding the next picture, in decoding order, associated with a depth representation information SEI message applicable to targetLayerId or to the end of the CLVS of the nuh_layer_id equal to targetLayerId, whichever is earlier in decoding order.

.z_near_flag equal to 0 specifies that the syntax elements specifying the nearest depth value are not present in the syntax structure. z_near_flag equal to 1 specifies that the syntax elements specifying the nearest depth value are present in the syntax structure.z_far_flag equal to 0 specifies that the syntax elements specifying the farthest depth value are not present in the syntax structure. z_far_flag equal to 1 specifies that the syntax elements specifying the farthest depth value are present in the syntax structure.d_min_flag equal to 0 specifies that the syntax elements specifying the minimum disparity value are not present in the syntax structure. d_min_flag equal to 1 specifies that the syntax elements specifying the minimum disparity value are present in the syntax structure.d_max_flag equal to 0 specifies that the syntax elements specifying the maximum disparity value are not present in the syntax structure. d_max_flag equal to 1 specifies that the syntax elements specifying the maximum disparity value are present in the syntax structure.depth_representation_type specifies the representation definition of decoded luma samples of auxiliary pictures as specified in Table Y1. In Table Y1, disparity specifies the horizontal displacement between two texture views and Z value specifies the distance from a camera.

The variable maxVal is set equal to (1<<(8+sps_bitdepth_minus8))−1, where sps_bitdepth_minus8 is the value included in or inferred for the active SPS of the layer with nuh_layer_id equal to targetLayerId.

TABLE Y1Definition of depth_representation_typedepth_represen-ation_typeInterpretation0Each decoded luma sample value of an auxiliary picture represents aninverse of Z value that is uniformly quantized into the range of 0 tomaxVal, inclusive.When z_far_flag is equal to 1, the luma sample value equal to 0represents the inverse of ZFar (specified below). When z_near_flag isequal to 1, the luma sample value equal to maxVal represents theinverse of ZNear (specified below).1Each decoded luma sample value of an auxiliary picture representsdisparity that is uniformly quantized into the range of 0 to maxVal,inclusive.When d_min_flag is equal to 1, the luma sample value equal to 0represents DMin (specified below). When d_max_flag is equal to 1, theluma sample value equal to maxVal represents DMax (specifiedbelow).2Each decoded luma sample value of an auxiliary picture represents a Zvalue uniformly quantized into the range of 0 to maxVal, inclusive.When z_far_flag is equal to 1, the luma sample value equal to 0corresponds to ZFar (specified below). When z_near_flag is equal to 1,the luma sample value equal to maxVal represents ZNear (specifiedbelow).3Each decoded luma sample value of an auxiliary picture represents anonlinearly mapped disparity, normalized in range from 0 to maxVal,as specified by depth_nonlinear_representation_num_minus1 anddepth_nonlinear_representation_model[ i ].When d_min_flag is equal to 1, the luma sample value equal to 0represents DMin (specified below). When d_max_flag is equal to 1, theluma sample value equal to maxVal represents DMax (specifiedbelow).Other valuesReserved for future usedisparity_ref_view_id specifies the ViewId value against which the disparity values are derived.

NOTE 1—disparity_ref_view_id is present only if d_min_flag is equal to 1 or d_max_flag is equal to 1 and is useful for depth_representation_type values equal to 1 and 3.

The variables in the x column of Table Y2 are derived from the respective variables in the s, e, n and v columns of Table Y2 as follows:If the value of e is in the range of 0 to 127, exclusive, x is set equal to (−1)s*2e-31*(1+n÷2v).Otherwise (e is equal to 0), x is set equal to (−1)s*2−(30+v)*n.

NOTE 1—The above specification is similar to that found in IEC 60559:1989.

TABLE Y2Association between depth parametervariables and syntax elementsxsenvZNearZNearSignZNearExpZNearMantissaZNearManLenZFarZFarSignZFarExpZFarMantissaZFarManLenDMaxDMaxSignDMaxExpDMaxMantissaDMaxManLenDMinDMinSignDMinExpDMinMantissaDMinManLen

The DMin and DMax values, when present, are specified in units of a luma sample width of the coded picture with ViewId equal to ViewId of the auxiliary picture.

The units for the ZNear and ZFar values, when present, are identical but unspecified.depth_nonlinear_representation_num_minus1 plus 2 specifies the number of piece-wise linear segments for mapping of depth values to a scale that is uniformly quantized in terms of disparity.depth_nonlinear_representation_model[i] for i ranging from 0 to depth_nonlinear_representation_num_minus1+2, inclusive, specify the piece-wise linear segments for mapping of decoded luma sample values of an auxiliary picture to a scale that is uniformly quantized in terms of disparity. The values ofdepth_nonlinear_representation_model[0] and depth_nonlinear_representation_model[depth_nonlinear_representation_num_minus1+2] are both inferred to be equal to 0.

NOTE 2—When depth_representation_type is equal to 3, an auxiliary picture contains nonlinearly transformed depth samples. The variable DepthLUT[i], as specified below, is used to transform decoded depth sample values from the nonlinear representation to the linear representation, i.e., uniformly quantized disparity values. The shape of this transform is defined by means of line-segment approximation in two-dimensional linear-disparity-to-nonlinear-disparity space. The first (0, 0) and the last (maxVal, maxVal) nodes of the curve are predefined. Positions of additional nodes are transmitted in form of deviations (depth_nonlinear_representation_model[i]) from the straight-line curve. These deviations are uniformly distributed along the whole range of 0 to maxVal, inclusive, with spacing depending on the value of nonlinear_depth_representation_num_minus1.

The variable DepthLUT[i] for i in the range of 0 to maxVal, inclusive, is specified as follows:

When depth_representation_type is equal to 3, DepthLUT[dS] for all decoded luma sample values dS of an auxiliary picture in the range of 0 to maxVal, inclusive, represents disparity that is uniformly quantized into the range of 0 to maxVal, inclusive.

The syntax structure specifies the value of an element in the depth representation information SEI message.

The syntax structure sets the values of the OutSign, OutExp, OutMantissa and OutManLen variables that represent a floating-point value. When the syntax structure is included in another syntax structure, the variable names OutSign, OutExp, OutMantissa and OutManLen are to be interpreted as being replaced by the variable names used when the syntax structure is included.da_sign_flag equal to 0 indicates that the sign of the floating-point value is positive. da_sign_flag equal to 1 indicates that the sign is negative. The variable OutSign is set equal to da_sign_flag.da_exponent specifies the exponent of the floating-point value. The value of da_exponent shall be in the range of 0 to 27−2, inclusive. The value 27−1 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 27−1 as indicating an unspecified value. The variable OutExp is set equal to da_exponent.da_mantissa_len_minus1 plus 1 specifies the number of bits in the da_mantissa syntax element. The value of da_mantissa_len_minus1 shall be in the range of 0 to 31, inclusive. The variable OutManLen is set equal to da_mantissa_len_minus1+1.da_mantissa specifies the mantissa of the floating-point value. The variable OutMantissa is set equal to da_mantissa.

Depth Representation Information SEI Message

Depth Representation Information SEI Message Syntax

Depth Representation Information SEI Message Semantics

When present, the depth representation information SEI message shall be associated with one or more layers with sdi_aux_id value equal to AUX_DEPTH. The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the depth representation information SEI message applies.

When present, the depth representation information SEI message may be included in any access unit. It is recommended that, when present, the SEI message is included for the purpose of random access in an access unit in which the coded picture with nuh_layer_id equal to targetLayerId is an TRAP picture.

For an auxiliary picture with sdi_aux_id[targetLayerId] equal to AUX_DEPTH, an associated primary picture, if any, is a picture in the same access unit having sdi_aux_id[nuhLayerIdB] equal to 0 such that ScalabilityId[LayerIdxInVps[targetLayerId]][j] is equal to ScalabilityId[LayerIdxInVps[nuhLayerIdB]][j] for all values of j in the range of 0 to 2, inclusive, and 4 to 15, inclusive.

The information indicated in the SEI message applies to all the pictures with nuh_layer_id equal to targetLayerId from the access unit containing the SEI message up to but excluding the next picture, in decoding order, associated with a depth representation information SEI message applicable to targetLayerId or to the end of the CLVS of the nuh_layer_id equal to targetLayerId, whichever is earlier in decoding order.

.z_near_flag equal to 0 specifies that the syntax elements specifying the nearest depth value are not present in the syntax structure. z_near_flag equal to 1 specifies that the syntax elements specifying the nearest depth value are present in the syntax structure.z_far_flag equal to 0 specifies that the syntax elements specifying the farthest depth value are not present in the syntax structure. z_far_flag equal to 1 specifies that the syntax elements specifying the farthest depth value are present in the syntax structure.d_min_flag equal to 0 specifies that the syntax elements specifying the minimum disparity value are not present in the syntax structure. d_min_flag equal to 1 specifies that the syntax elements specifying the minimum disparity value are present in the syntax structure.d_max_flag equal to 0 specifies that the syntax elements specifying the maximum disparity value are not present in the syntax structure. d_max_flag equal to 1 specifies that the syntax elements specifying the maximum disparity value are present in the syntax structure.depth_representation_type specifies the representation definition of decoded luma samples of auxiliary pictures as specified in Table Y1. In Table Y1, disparity specifies the horizontal displacement between two texture views and Z value specifies the distance from a camera.

The variable maxVal is set equal to (1<<<(8+sps_bitdepth_minus8))−1, where sps_bitdepth_minus8 is the value included in or inferred for the active SPS of the layer with nuh_layer_id equal to targetLayerId.

TABLE Y1Definition of depth_representation_typedepth_represen-ation_typeInterpretation0Each decoded luma sample value of an auxiliary picture represents aninverse of Z value that is uniformly quantized into the range of 0 tomaxVal, inclusive.When z_far_flag is equal to 1, the luma sample value equal to 0represents the inverse of ZFar (specified below). When z_near_flag isequal to 1, the luma sample value equal to maxVal represents theinverse of ZNear (specified below).1Each decoded luma sample value of an auxiliary picture representsdisparity that is uniformly quantized into the range of 0 to maxVal,inclusive.When d_min_flag is equal to 1, the luma sample value equal to 0represents DMin (specified below). When d_max_flag is equal to 1, theluma sample value equal to maxVal represents DMax (specifiedbelow).2Each decoded luma sample value of an auxiliary picture represents a Zvalue uniformly quantized into the range of 0 to maxVal, inclusive.When z_far_flag is equal to 1, the luma sample value equal to 0corresponds to ZFar (specified below). When z_near_flag is equal to 1,the luma sample value equal to maxVal represents ZNear (specifiedbelow).3Each decoded luma sample value of an auxiliary picture represents anonlinearly mapped disparity, normalized in range from 0 to maxVal,as specified by depth_nonlinear_representation_num_minus1 anddepth_nonlinear_representation_model[ i ].When d_min_flag is equal to 1, the luma sample value equal to 0represents DMin (specified below). When d_max_flag is equal to 1, theluma sample value equal to maxVal represents DMax (specifiedbelow).Other valuesReserved for future usedisparity_ref_view_id specifies the ViewId value against which the disparity values are derived.

NOTE 1—disparity_ref_view_id is present only if d_min_flag is equal to 1 or d_max_flag is equal to 1 and is useful for depth_representation_type values equal to 1 and 3.

The variables in the x column of Table Y2 are derived from the respective variables in the s, e, n and v columns of Table Y2 as follows:If the value of e is in the range of 0 to 127, exclusive, x is set equal to (−1)s*2e-31*(1+n÷2v).Otherwise (e is equal to 0), x is set equal to (−1)s*2−(30+v)*n.

NOTE 1—The above specification is similar to that found in IEC 60559:1989.

TABLE Y2Association between depth parametervariables and syntax elementsxsenvZNearZNearSignZNearExpZNearMantissaZNearManLenZFarZFarSignZFarExpZFarMantissaZFarManLenDMaxDMaxSignDMaxExpDMaxMantissaDMaxManLenDMinDMinSignDMinExpDMinMantissaDMinManLen

The DMin and DMax values, when present, are specified in units of a luma sample width of the coded picture with ViewId equal to ViewId of the auxiliary picture.

The units for the ZNear and ZFar values, when present, are identical but unspecified.depth_nonlinear_representation_num_minus1 plus 2 specifies the number of piece-wise linear segments for mapping of depth values to a scale that is uniformly quantized in terms of disparity.depth_nonlinear_representation_model[i] for i ranging from 0 to depth_nonlinear_representation_num_minus1+2, inclusive, specify the piece-wise linear segments for mapping of decoded luma sample values of an auxiliary picture to a scale that is uniformly quantized in terms of disparity. The values of depth_nonlinear_representation_model[0] and depth_nonlinear_representation_model[depth_nonlinear_representation_num_minus1+2] are both inferred to be equal to 0.

NOTE 2—When depth_representation_type is equal to 3, an auxiliary picture contains nonlinearly transformed depth samples. The variable DepthLUT[i], as specified below, is used to transform decoded depth sample values from the nonlinear representation to the linear representation, i.e., uniformly quantized disparity values. The shape of this transform is defined by means of line-segment approximation in two-dimensional linear-disparity-to-nonlinear-disparity space. The first (0, 0) and the last (maxVal, maxVal) nodes of the curve are predefined. Positions of additional nodes are transmitted in form of deviations (depth_nonlinear_representation_model[i]) from the straight-line curve. These deviations are uniformly distributed along the whole range of 0 to maxVal, inclusive, with spacing depending on the value of nonlinear_depth_representation_num_minus1.

The variable DepthLUT[i] for i in the range of 0 to maxVal, inclusive, is specified as follows:

When depth_representation_type is equal to 3, DepthLUT[dS] for all decoded luma sample values dS of an auxiliary picture in the range of 0 to maxVal, inclusive, represents disparity that is uniformly quantized into the range of 0 to maxVal, inclusive.

The syntax structure specifies the value of an element in the depth representation information SEI message.

The syntax structure sets the values of the OutSign, OutExp, OutMantissa and OutManLen variables that represent a floating-point value. When the syntax structure is included in another syntax structure, the variable names OutSign, OutExp, OutMantissa and OutManLen are to be interpreted as being replaced by the variable names used when the syntax structure is included.da_sign_flag equal to 0 indicates that the sign of the floating-point value is positive. da_sign_flag equal to 1 indicates that the sign is negative. The variable OutSign is set equal to da_sign_flag.da_exponent specifies the exponent of the floating-point value. The value of da_exponent shall be in the range of 0 to 27−2, inclusive. The value 27−1 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 27−1 as indicating an unspecified value. The variable OutExp is set equal to da_exponent.da_mantissa_len_minus1 plus 1 specifies the number of bits in the da_mantissa syntax element. The value of da_mantissa_len_minus1 shall be in the range of 0 to 31, inclusive. The variable OutManLen is set equal to da_mantissa_len_minus1+1.da_mantissa specifies the mantissa of the floating-point value. The variable OutMantissa is set equal to da_mantissa.

Alpha Channel Information SEI Message

Alpha Channel Information SEI Message Syntax

Alpha Channel Information SEI Message Semantics

The alpha channel information SEI message provides information about alpha channel sample values and post-processing applied to the decoded alpha planes coded in auxiliary pictures of type AUX_ALPHA and one or more associated primary pictures.

For an auxiliary picture with nuh_layer_id equal to nuhLayerIdA and sdi_aux_id[nuhLayerIdA] equal to AUX_ALPHA, an associated primary picture, if any, is a picture in the same access unit having sdi_aux_id[nuhLayerIdB] equal to 0 such that ScalabilityId[LayerIdxInVps[nuhLayerIdA]][j] is equal to ScalabilityId[LayerIdxInVps[nuhLayerIdB]][j] for all values of j in the range of 0 to 2, inclusive, and 4 to 15, inclusive.

When an access unit contains an auxiliary picture picA with nuh_layer_id equal to nuhLayerIdA and sdi_aux_id[nuhLayerIdA] equal to AUX_ALPHA, the alpha channel sample values of picA persist in output order until one or more of the following conditions are true:The next picture, in output order, with nuh_layer_id equal to nuhLayerIdA is output.A CLVS containing the auxiliary picture picA ends.The bitstream ends.A CLVS of any associated primary layer of the auxiliary picture layer with nuh_layer_id equal to nuhLayerIdA ends.

The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the alpha channel information SEI message applies.alpha_channel_primary_layer_id specifies the nuh_layer_id value of the associated primary layer to which the alpha channel information SEI applies to.alpha_channel_cancel_flag equal to 1 indicates that the alpha channel information SEI message cancels the persistence of any previous alpha channel information SEI message in output order that applies to the current layer. alpha_channel_cancel_flag equal to 0 indicates that alpha channel information follows.

Let currPic be the picture that the alpha channel information SEI message is associated with. The semantics of alpha channel information SEI message persist for the current layer in output order until one or more of the following conditions are true:A new CLVS of the current layer begins.The bitstream ends.A picture picB with nuh_layer_id equal to targetLayerId in an access unit containing an alpha channel information SEI message with nuh_layer_id equal to targetLayerId is output having PicOrderCnt(picB) greater than PicOrderCnt(currPic), where PicOrderCnt(picB) and PicOrderCnt(currPic) are the PicOrderCntVal values of picB and currPic, respectively, immediately after the invocation of the decoding process for picture order count for picB.alpha_channel_use_idc equal to 0 indicates that for alpha blending purposes the decoded samples of the associated primary picture should be multiplied by the interpretation sample values of the auxiliary coded picture in the display process after output from the decoding process. alpha_channel_use_idc equal to 1 indicates that for alpha blending purposes the decoded samples of the associated primary picture should not be multiplied by the interpretation sample values of the auxiliary coded picture in the display process after output from the decoding process. alpha_channel_use_idc equal to 2 indicates that the usage of the auxiliary picture is unspecified. Values greater than 2 for alpha_channel_use_idc are reserved for future use by ITU-T|ISO/IEC. When not present, the value of alpha_channel_use_idc is inferred to be equal to 2.alpha_channel_bit_depth_minus8 plus 8 specifies the bit depth of the samples of the luma sample array of the auxiliary picture. alpha_channel_bit_depth_minus8 shall be in the range 0 to 7 inclusive. alpha_channel_bit_depth_minus8 shall be equal to bit_depth_luma_minus8 of the associated primary picture.alpha_transparent_value specifies the interpretation sample value of an auxiliary coded picture luma sample for which the associated luma and chroma samples of the primary coded picture are considered transparent for purposes of alpha blending. The number of bits used for the representation of the alpha_transparent_value syntax element is alpha_channel_bit_depth_minus8+9.alpha_opaque_value specifies the interpretation sample value of an auxiliary coded picture luma sample for which the associated luma and chroma samples of the primary coded picture are considered opaque for purposes of alpha blending. The number of bits used for the representation of the alpha_opaque_value syntax element is alpha_channel_bit_depth_minus8+9.alpha_channel_incr_flag equal to 0 indicates that the interpretation sample value for each decoded auxiliary picture luma sample value is equal to the decoded auxiliary picture sample value for purposes of alpha blending. alpha_channel_incr_flag equal to 1 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample value that is greater than Min(alpha_opaque_value, alpha_transparent_value) should be increased by one to obtain the interpretation sample value for the auxiliary picture sample and any auxiliary picture luma sample value that is less than or equal to Min(alpha_opaque_value, alpha_transparent_value) should be used, without alteration, as the interpretation sample value for the decoded auxiliary picture sample value. When not present, the value of alpha_channel_incr_flag is inferred to be equal to 0.alpha_channel_clip_flag equal to 0 indicates that no clipping operation is applied to obtain the interpretation sample values of the decoded auxiliary picture. alpha_channel_clip_flag equal to 1 indicates that the interpretation sample values of the decoded auxiliary picture are altered according to the clipping process described by the alpha_channel_clip_type_flag syntax element. When not present, the value of alpha_channel_clip_flag is inferred to be equal to 0.alpha_channel_clip_type_flag equal to 0 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample that is greater than (alpha_opaque_value−alpha_transparent_value)/2 is set equal to alpha_opaque_value to obtain the interpretation sample value for the auxiliary picture luma sample and any auxiliary picture luma sample that is less or equal than (alpha_opaque_value−alpha_transparent_value)/2 is set equal to alpha_transparent_value to obtain the interpretation sample value for the auxiliary picture luma sample. alpha_channel_clip_type_flag equal to 1 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample that is greater than alpha_opaque_value is set equal to alpha_opaque_value to obtain the interpretation sample value for the auxiliary picture luma sample and any auxiliary picture luma sample that is less than or equal to alpha_transparent_value is set equal to alpha_transparent_value to obtain the interpretation sample value for the auxiliary picture luma sample.

NOTE—When both alpha_channel_incr_flag and alpha_channel_clip_flag are equal to one, the clipping operation specified by alpha_channel_clip_type_flag should be applied first followed by the alteration specified by alpha_channel_incr_flag to obtain the interpretation sample value for the auxiliary picture luma sample.

Alpha Channel Information SEI Message

Alpha Channel Information SEI Message Syntax

Alpha Channel Information SEI Message Semantics

The alpha channel information SEI message provides information about alpha channel sample values and post-processing applied to the decoded alpha planes coded in auxiliary pictures of type AUX_ALPHA and one or more associated primary pictures.

For an auxiliary picture with nuh_layer_id equal to nuhLayerIdA and sdi_aux_id[nuhLayerIdA] equal to AUX_ALPHA, an associated primary picture, if any, is a picture in the same access unit having sdi_aux_id[nuhLayerIdB] equal to 0 such that ScalabilityId[LayerIdxInVps[nuhLayerIdA]][j] is equal to ScalabilityId[LayerIdxInVps[nuhLayerIdB]][j] for all values of j in the range of 0 to 2, inclusive, and 4 to 15, inclusive.

When an access unit contains an auxiliary picture picA with nuh_layer_id equal to nuhLayerIdA and sdi_aux_id[nuhLayerIdA] equal to AUX_ALPHA, the alpha channel sample values of picA persist in output order until one or more of the following conditions are true:The next picture, in output order, with nuh_layer_id equal to nuhLayerIdA is output.A CLVS containing the auxiliary picture picA ends.The bitstream ends.A CLVS of any associated primary layer of the auxiliary picture layer with nuh_layer_id equal to nuhLayerIdA ends.

The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the alpha channel information SEI message applies.alpha_channel_cancel_flag equal to 1 indicates that the alpha channel information SEI message cancels the persistence of any previous alpha channel information SEI message in output order that applies to the current layer. alpha_channel_cancel_flag equal to 0 indicates that alpha channel information follows.

Let currPic be the picture that the alpha channel information SEI message is associated with. The semantics of alpha channel information SEI message persist for the current layer in output order until one or more of the following conditions are true:A new CLVS of the current layer begins.The bitstream ends.A picture picB with nuh_layer_id equal to targetLayerId in an access unit containing an alpha channel information SEI message with nuh_layer_id equal to targetLayerId is output having PicOrderCnt(picB) greater than PicOrderCnt(currPic), where PicOrderCnt(picB) and PicOrderCnt(currPic) are the PicOrderCntVal values of picB and currPic, respectively, immediately after the invocation of the decoding process for picture order count for picB...alpha_channel_use_idc equal to 0 indicates that for alpha blending purposes the decoded samples of the associated primary picture should be multiplied by the interpretation sample values of the auxiliary coded picture in the display process after output from the decoding process. alpha_channel_use_idc equal to 1 indicates that for alpha blending purposes the decoded samples of the associated primary picture should not be multiplied by the interpretation sample values of the auxiliary coded picture in the display process after output from the decoding process. alpha_channel_use_idc equal to 2 indicates that the usage of the auxiliary picture is unspecified. Values greater than 2 for alpha_channel_use_idc are reserved for future use by ITU-T|ISO/IEC. When not present, the value of alpha_channel_use_idc is inferred to be equal to 2.alpha_channel_bit_depth_minus8 plus 8 specifies the bit depth of the samples of the luma sample array of the auxiliary picture. alpha_channel_bit_depth_minus8 shall be in the range 0 to 7 inclusive. alpha_channel_bit_depth_minus8 shall be equal to bit_depth_luma_minus8 of the associated primary picture.alpha_transparent_value specifies the interpretation sample value of an auxiliary coded picture luma sample for which the associated luma and chroma samples of the primary coded picture are considered transparent for purposes of alpha blending. The number of bits used for the representation of the alpha_transparent_value syntax element is alpha_channel_bit_depth_minus8+9.alpha_opaque_value specifies the interpretation sample value of an auxiliary coded picture luma sample for which the associated luma and chroma samples of the primary coded picture are considered opaque for purposes of alpha blending. The number of bits used for the representation of the alpha_opaque_value syntax element is alpha_channel_bit_depth_minus8+9.alpha_channel_incr_flag equal to 0 indicates that the interpretation sample value for each decoded auxiliary picture luma sample value is equal to the decoded auxiliary picture sample value for purposes of alpha blending. alpha_channel_incr_flag equal to 1 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample value that is greater than Min(alpha_opaque_value, alpha_transparent_value) should be increased by one to obtain the interpretation sample value for the auxiliary picture sample and any auxiliary picture luma sample value that is less than or equal to Min(alpha_opaque_value, alpha_transparent_value) should be used, without alteration, as the interpretation sample value for the decoded auxiliary picture sample value. When not present, the value of alpha_channel_incr_flag is inferred to be equal to 0.alpha_channel_clip_flag equal to 0 indicates that no clipping operation is applied to obtain the interpretation sample values of the decoded auxiliary picture. alpha_channel_clip_flag equal to 1 indicates that the interpretation sample values of the decoded auxiliary picture are altered according to the clipping process described by the alpha_channel_clip_type_flag syntax element. When not present, the value of alpha_channel_clip_flag is inferred to be equal to 0.alpha_channel_clip_type_flag equal to 0 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample that is greater than (alpha_opaque_value−alpha_transparent_value)/2 is set equal to alpha_opaque_value to obtain the interpretation sample value for the auxiliary picture luma sample and any auxiliary picture luma sample that is less or equal than (alpha_opaque_value−alpha_transparent_value)/2 is set equal to alpha_transparent_value to obtain the interpretation sample value for the auxiliary picture luma sample. alpha_channel_clip_type_flag equal to 1 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample that is greater than alpha_opaque_value is set equal to alpha_opaque_value to obtain the interpretation sample value for the auxiliary picture luma sample and any auxiliary picture luma sample that is less than or equal to alpha_transparent_value is set equal to alpha_transparent_value to obtain the interpretation sample value for the auxiliary picture luma sample.

NOTE—When both alpha_channel_incr_flag and alpha_channel_clip_flag are equal to one, the clipping operation specified by alpha_channel_clip_type_flag should be applied first followed by the alteration specified by alpha_channel_incr_flag to obtain the interpretation sample value for the auxiliary picture luma sample.

Multiview Acquisition Information SEI Message

Multiview Acquisition Information SEI Message Syntax

Multiview Acquisition Information SEI Message Semantics

The multiview acquisition information (MAI) SEI message specifies various parameters of the acquisition environment. Specifically, intrinsic and extrinsic camera parameters are specified. These parameters could be used for processing the decoded views prior to rendering on a 3D display.

The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the multiview acquisition information SEI message applies.

When present, the multiview acquisition information SEI message that applies to the current layer shall be included in an access unit that contains an TRAP picture that is the first picture of a CLVS of the current layer. The information signalled in the SEI message applies to the CLVS.

An MAI SEI message that has payloadType equal to 179 (multiview acquisition) shall not be contained in a scalable nesting SEI message.

Let the current AU be the AU containing the current MAI SEI message, and the current CVS be the CVS containing the current AU.

When a CVS does not contain an SDI SEI message, the CVS shall not contain an MAI SEI message.

When an AU contains both an SDI SEI message and an MAI SEI message, the SDI SEI message shall precede the MAI SEI message in decoding order.

When the multiview acquisition information SEI message is contained in a scalable nesting SEI message, the syntax elements sn_ols_flag and sn_all_layers_flag in the scalable nesting SEI message shall be equal to 0.

The variable numViewsMinus1 is derived as follows:If the multiview acquisition information SEI message is not included in a scalable nesting SEI message, numViewsMinus1 is set equal to 0.Otherwise (the multiview acquisition information SEI message is included in a scalable nesting SEI message), numViewsMinus1 is set equal to sn_num_layers_minus1.

Some of the views for which the multiview acquisition information is included in a multiview acquisition information SEI message may not be present.

In the semantics below, index i refers to the syntax elements and variables that apply to the layer with nuh_layer_id equal to NestingLayerId[i].

The extrinsic camera parameters are specified according to a right-handed coordinate system, where the upper left corner of the image is the origin, i.e., the (0, 0) coordinate, with the other corners of the image having non-negative coordinates. With these specifications, a 3-dimensional world point, wP=[x y z] is mapped to a 2-dimensional camera point, cP[i]=[u v 1], for the i-th camera according to:

where A[i] denotes the intrinsic camera parameter matrix, R−1[i] denotes the inverse of the rotation matrix R[i], T[i] denotes the translation vector and s (a scalar value) is an arbitrary scale factor chosen to make the third coordinate of cP[i] equal to 1. The elements of A[i], R[i] and T[i] are determined according to the syntax elements signalled in this SEI message and as specified below.intrinsic_param_flag equal to 1 indicates the presence of intrinsic camera parameters. intrinsic_param_flag equal to 0 indicates the absence of intrinsic camera parameters.extrinsic_param_flag equal to 1 indicates the presence of extrinsic camera parameters. extrinsic_param_flag equal to 0 indicates the absence of extrinsic camera parameters.intrinsic_params_equal_flag equal to 1 indicates that the intrinsic camera parameters are equal for all cameras and only one set of intrinsic camera parameters are present.intrinsic_params_equal_flag equal to 0 indicates that the intrinsic camera parameters are different for each camera and that a set of intrinsic camera parameters are present for each camera.prec_focal_length specifies the exponent of the maximum allowable truncation error for focal_length_x[i] and focal_length_y[i] as given by 2−prec_focal_length. The value of prec_focal_length shall be in the range of 0 to 31, inclusive.prec_principal_point specifies the exponent of the maximum allowable truncation error for principal_point_x[i] and principal_point_y[i] as given by 2−prec_principal_point. The value of prec_principal_point shall be in the range of 0 to 31, inclusive.prec_skew_factor specifies the exponent of the maximum allowable truncation error for skew factor as given by 2−prec_skew_factor. The value of prec_skew_factor shall be in the range of 0 to 31, inclusive.sign_focal_length_x[i] equal to 0 indicates that the sign of the focal length of the i-th camera in the horizontal direction is positive. sign_focal_length_x[i] equal to 1 indicates that the sign is negative.exponent_focal_length_x[i] specifies the exponent part of the focal length of the i-th camera in the horizontal direction. The value of exponent_focal_length_x[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified focal length.mantissa_focal_length_x[i] specifies the mantissa part of the focal length of the i-th camera in the horizontal direction. The length of the mantissa_focal_length_x[i] syntax element is variable and determined as follows:If exponent_focal_length_x[i] is equal to 0, the length is Max(0, prec_focal_length−30).Otherwise (exponent_focal_length_x[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_focal_length_x[i]+prec_focal_length−31).sign_focal_length_y[i] equal to 0 indicates that the sign of the focal length of the i-th camera in the vertical direction is positive. sign_focal_length_y[i] equal to 1 indicates that the sign is negative.exponent_focal_length_y[i] specifies the exponent part of the focal length of the i-th camera in the vertical direction. The value of exponent_focal_length_y[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified focal length.mantissa_focal_length_y[i] specifies the mantissa part of the focal length of the i-th camera in the vertical direction.

The length of the mantissa_focal_length_y[i] syntax element is variable and determined as follows:If exponent_focal_length_y[i] is equal to 0, the length is Max(0, prec_focal_length−30).Otherwise (exponent_focal_length_y[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_focal_length_y[i]+prec_focal_length−31).sign_principal_point_x[i] equal to 0 indicates that the sign of the principal point of the i-th camera in the horizontal direction is positive. sign_principal_point_x[i] equal to 1 indicates that the sign is negative.exponent_principal_point_x[i] specifies the exponent part of the principal point of the i-th camera in the horizontal direction. The value of exponent_principal_point_x[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified principal point.mantissa_principal_point_x[i] specifies the mantissa part of the principal point of the i-th camera in the horizontal direction. The length of the mantissa_principal_point_x[i] syntax element in units of bits is variable and is determined as follows:If exponent_principal_point_x[i] is equal to 0, the length is Max(0, prec_principal_point−30).Otherwise (exponent_principal_point_x[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_principal_point_x[i]+prec_principal_point−31).sign_principal_point_y[i] equal to 0 indicates that the sign of the principal point of the i-th camera in the vertical direction is positive. sign_principal_point_y[i] equal to 1 indicates that the sign is negative.exponent_principal_point_y[i] specifies the exponent part of the principal point of the i-th camera in the vertical direction. The value of exponent_principal_point_y[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified principal point.mantissa_principal_point_y[i] specifies the mantissa part of the principal point of the i-th camera in the vertical direction. The length of the mantissa_principal_point_y[i] syntax element in units of bits is variable and is determined as follows:If exponent_principal_point_y[i] is equal to 0, the length is Max(0, prec_principal_point−30).Otherwise (exponent_principal_point_y[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_principal_point_y[i]+prec_principal_point−31).sign_skew_factor[i] equal to 0 indicates that the sign of the skew factor of the i-th camera is positive.sign_skew_factor[i] equal to 1 indicates that the sign is negative.exponent_skew_factor[i] specifies the exponent part of the skew factor of the i-th camera. The value of exponent_skew_factor[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified skew factor.mantissa_skew_factor[i] specifies the mantissa part of the skew factor of the i-th camera. The length of the mantissa_skew_factor[i] syntax element is variable and determined as follows:If exponent_skew_factor[i] is equal to 0, the length is Max(0, prec_skew_factor−30).Otherwise (exponent_skew_factor[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_skew_factor[i]+prec_skew_factor−31).

The intrinsic matrix A[i] for i-th camera is represented by

prec_rotation_param specifies the exponent of the maximum allowable truncation error for r[i][j][k] as given by 2−prec_rotation_param. The value of prec_rotation_param shall be in the range of 0 to 31, inclusive.prec_translation_param specifies the exponent of the maximum allowable truncation error for t[i][j] as given by 2−prec_translation_param. The value of prec_translation_param shall be in the range of 0 to 31, inclusive.sign_r[i][j][k] equal to 0 indicates that the sign of (j, k) component of the rotation matrix for the i-th camera is positive. sign_r[i][j][k] equal to 1 indicates that the sign is negative.exponent_r[i][j][k] specifies the exponent part of (j, k) component of the rotation matrix for the i-th camera. The value of exponent_r[i][j][k] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified rotation matrix.mantissa_r[i][j][k] specifies the mantissa part of (j, k) component of the rotation matrix for the i-th camera. The length of the mantissa_r[i][j][k] syntax element in units of bits is variable and determined as follows:If exponent_r[i] is equal to 0, the length is Max(0, prec_rotation_param−30).Otherwise (exponent_r[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_r[i]+prec_rotation_param−31).

The rotation matrix R[i] for i-th camera is represented as follows:

[rE[i][0][0]rE[i][0][1]rE[i][0][2]rE[i][1][0]rE[i][1][1]rE[i][1][2]rE[i][2][0]rE[i][2][1]rE[i][2][2]](X)sign_t[i][j] equal to 0 indicates that the sign of the j-th component of the translation vector for the i-th camera is positive. sign_t[i] [j] equal to 1 indicates that the sign is negative.exponent_t[i][j] specifies the exponent part of the j-th component of the translation vector for the i-th camera. The value of exponent_t[i][j] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified translation vector.mantissa_t[i][j] specifies the mantissa part of the j-th component of the translation vector for the i-th camera. The length v of the mantissa_t[i][j] syntax element in units of bits is variable and is determined as follows:If exponent_t[i] is equal to 0, the length v is set equal to Max(0, prec_translation_param−30).Otherwise (0<exponent_t[i]<63), the length v is set equal to Max(0, exponent_t[i]+prec_translation_param−31).

The translation vector T[i] for the i-th camera is represented by:

The association between the camera parameter variables and corresponding syntax elements is specified by Table ZZ. Each component of the intrinsic and rotation matrices and the translation vector is obtained from the variables specified in Table ZZ as the variable x computed as follows:If e is in the range of 0 to 63, exclusive, x is set equal to (−1)s*2e-31*(1+n÷2v).Otherwise (e is equal to 0), x is set equal to (−1)s*2−(30+v)*n.

NOTE—The above specification is similar to that found in IEC 60559:1989.

TABLE ZZAssociation between camera parameter variables and syntax elements.xsenfocalLengthX[ i ]sign_focal_length_x[i]exponent_focal_lengthx[ i ]mantissa_focal_lengthx[ i ]focalLengthY[ i ]sign_focal_length_y[ i ]exponent_focal_lengthy[ i]mantissa_focal_lengthy[ i ]principalPointX[ i ]sign_principal_point_x[ i ]exponent_principal_point_x[ i ]mantissa_principal_point_x[ i ]principalPointY[ i ]sign_principal_point_y[ i ]exponent_principal_point_y[ i ]mantissa_principal_point_y[ i ]skewFactor[ i ]sign_skew_factor[ i ]exponent_skew_factor[ i ]mantissa_skew_factor[ i ]rE[ i ][ j ][ k ]sign_r[ i ][ j ][ k ]exponent_r[ i ][ j ][ k ]mantissa_r[ i ][ j ][ k ]tE[ i ][ j ]sign_t[ i ][ j ]exponent_t[ i ][ j ]mantissa_t[ i ][ j ]

Depth Representation Information SEI Message

Depth Representation Information SEI Message Syntax

Depth Representation Information SEI Message Semantics

When present, the depth representation information SEI message shall be associated with one or more layers with sdi_aux_id value equal to AUX_DEPTH. The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the depth representation information SEI message applies.

When present, the depth representation information SEI message may be included in any access unit. It is recommended that, when present, the SEI message is included for the purpose of random access in an access unit in which the coded picture with nuh_layer_id equal to targetLayerId is an TRAP picture.

It is a requirement of bitstream conformance that the depth representation information SEI message shall not be present in the bitstream in which the scalability dimension information SEI message is not present.

For an auxiliary picture with sdi_aux_id[targetLayerId] equal to AUX_DEPTH, an associated primary picture, if any, is a picture in the same access unit having sdi_aux_id[nuhLayerIdB] equal to 0 such that ScalabilityId[LayerIdxInVps[targetLayerId]][j] is equal to ScalabilityId[LayerIdxInVps[nuhLayerIdB]][j] for all values of j in the range of 0 to 2, inclusive, and 4 to 15, inclusive.

The information indicated in the SEI message applies to all the pictures with nuh_layer_id equal to targetLayerId from the access unit containing the SEI message up to but excluding the next picture, in decoding order, associated with a depth representation information SEI message applicable to targetLayerId or to the end of the CLVS of the nuh_layer_id equal to targetLayerId, whichever is earlier in decoding order.z_near_flag equal to 0 specifies that the syntax elements specifying the nearest depth value are not present in the syntax structure. z_near_flag equal to 1 specifies that the syntax elements specifying the nearest depth value are present in the syntax structure.z_far_flag equal to 0 specifies that the syntax elements specifying the farthest depth value are not present in the syntax structure. z_far_flag equal to 1 specifies that the syntax elements specifying the farthest depth value are present in the syntax structure.d_min_flag equal to 0 specifies that the syntax elements specifying the minimum disparity value are not present in the syntax structure. d_min_flag equal to 1 specifies that the syntax elements specifying the minimum disparity value are present in the syntax structure.d_max_flag equal to 0 specifies that the syntax elements specifying the maximum disparity value are not present in the syntax structure. d_max_flag equal to 1 specifies that the syntax elements specifying the maximum disparity value are present in the syntax structure.depth_representation_type specifies the representation definition of decoded luma samples of auxiliary pictures as specified in Table Y1. In Table Y1, disparity specifies the horizontal displacement between two texture views and Z value specifies the distance from a camera.

The variable maxVal is set equal to (1<<<(8+sps_bitdepth_minus8))−1, where sps_bitdepth_minus8 is the value included in or inferred for the active SPS of the layer with nuh_layer_id equal to targetLayerId.

TABLE Y1Definition of depth_representation_typedepth_representation_typeInterpretation0Each decoded luma sample value of an auxiliary picture represents aninverse of Z value that is uniformly quantized into the range of 0 tomaxVal, inclusive.When z_far_flag is equal to 1, the luma sample value equal to 0represents the inverse of ZFar (specified below). When z_near_flag isequal to 1, the luma sample value equal to maxVal represents theinverse of ZNear (specified below).1Each decoded luma sample value of an auxiliary picture representsdisparity that is uniformly quantized into the range of 0 to maxVal,inclusive.When d_min_flag is equal to 1, the luma sample value equal to 0represents DMin (specified below). When d_max_flag is equal to 1, theluma sample value equal to maxVal represents DMax (specifiedbelow).2Each decoded luma sample value of an auxiliary picture represents a Zvalue uniformly quantized into the range of 0 to max Val, inclusive.When z_far_flag is equal to 1, the luma sample value equal to 0corresponds to ZFar (specified below). When z_near_flag is equal to 1,the luma sample value equal to maxVal represents ZNear (specifiedbelow).3Each decoded luma sample value of an auxiliary picture represents anonlinearly mapped disparity, normalized in range from 0 to maxVal,as specified by depth_nonlinear_representation_num_minus1 anddepth_nonlinear_representation_model[ i ].When d_min_flag is equal to 1, the luma sample value equal to 0represents DMin (specified below). When d_max_flag is equal to 1, theluma sample value equal to maxVal represents DMax (specifiedbelow).Other valuesReserved for future usedisparity_ref_view_id specifies the ViewId value against which the disparity values are derived.

NOTE 1—disparity_ref_view_id is present only if d_min_flag is equal to 1 or d_max_flag is equal to 1 and is useful for depth_representation_type values equal to 1 and 3.

The variables in the x column of Table Y2 are derived from the respective variables in the s, e, n and v columns of Table Y2 as follows:If the value of e is in the range of 0 to 127, exclusive, x is set equal to (−1)s*2e-31*(1+n÷2v).Otherwise (e is equal to 0), x is set equal to (−1)s*2−(30+v)*n.

NOTE 1—The above specification is similar to that found in IEC 60559:1989.

TABLE Y2Association between depth parametervariables and syntax elementsxsenvZNearZNearSignZNearExpZNearMantissaZNearManLenZFarZFarSignZFarExpZFarMantissaZFarManLenDMaxDMaxSignDMaxExpDMaxMantissaDMaxManLenDMinDMinSignDMinExpDMinMantissaDMinManLen

The DMin and DMax values, when present, are specified in units of a luma sample width of the coded picture with ViewId equal to ViewId of the auxiliary picture.

The units for the ZNear and ZFar values, when present, are identical but unspecified.depth_nonlinear_representation_num_minus1 plus 2 specifies the number of piece-wise linear segments for mapping of depth values to a scale that is uniformly quantized in terms of disparity.depth_nonlinear_representation_model[i] for i ranging from 0 to depth_nonlinear_representation_num_minus1+2, inclusive, specify the piece-wise linear segments for mapping of decoded luma sample values of an auxiliary picture to a scale that is uniformly quantized in terms of disparity. The values of depth_nonlinear_representation_model[0] and depth_nonlinear_representation_model[depth_nonlinear_representation_num_minus1+2] are both inferred to be equal to 0.

NOTE 2—When depth_representation_type is equal to 3, an auxiliary picture contains nonlinearly transformed depth samples. The variable DepthLUT[i], as specified below, is used to transform decoded depth sample values from the nonlinear representation to the linear representation, i.e., uniformly quantized disparity values. The shape of this transform is defined by means of line-segment approximation in two-dimensional linear-disparity-to-nonlinear-disparity space. The first (0, 0) and the last (maxVal, maxVal) nodes of the curve are predefined. Positions of additional nodes are transmitted in form of deviations (depth_nonlinear_representation_model[i]) from the straight-line curve. These deviations are uniformly distributed along the whole range of 0 to maxVal, inclusive, with spacing depending on the value of nonlinear_depth_representation_num_minus1.

The variable DepthLUT[i] for i in the range of 0 to maxVal, inclusive, is specified as follows:

When depth_representation_type is equal to 3, DepthLUT[dS] for all decoded luma sample values dS of an auxiliary picture in the range of 0 to maxVal, inclusive, represents disparity that is uniformly quantized into the range of 0 to maxVal, inclusive.

The syntax structure specifies the value of an element in the depth representation information SEI message.

The syntax structure sets the values of the OutSign, OutExp, OutMantissa and OutManLen variables that represent a floating-point value. When the syntax structure is included in another syntax structure, the variable names OutSign, OutExp, OutMantissa and OutManLen are to be interpreted as being replaced by the variable names used when the syntax structure is included.da_sign_flag equal to 0 indicates that the sign of the floating-point value is positive. da_sign_flag equal to 1 indicates that the sign is negative. The variable OutSign is set equal to da_sign_flag.da_exponent specifies the exponent of the floating-point value. The value of da_exponent shall be in the range of 0 to 27−2, inclusive. The value 27−1 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 27−1 as indicating an unspecified value. The variable OutExp is set equal to da_exponent.da_mantissa_len_minus1 plus 1 specifies the number of bits in the da_mantissa syntax element. The value of da_mantissa_len_minus1 shall be in the range of 0 to 31, inclusive. The variable OutManLen is set equal to da_mantissa_len_minus1+1.da_mantissa specifies the mantissa of the floating-point value. The variable OutMantissa is set equal to da_mantissa.

Depth Representation Information SEI Message

Depth Representation Information SEI Message Syntax

Depth Representation Information SEI Message Semantics

When a CVS does not contain an SDI SEI message with sdi_aux_id[i] equal to 2 for at least one value of i, no picture in the CVS shall be associated with a DRI SEI message.

When an AU contains both an SDI SEI message with sdi_aux_id[i] equal to 2 for at least one value of i and a DRI SEI message, the SDI SEI message shall precede the DRI SEI message in decoding order.

When present, the depth representation information SEI message shall be associated with one or more layers that are indicated as depth auxiliary layers by an SDI SEI message with sdi_aux_id value equal to AUX_DEPTH. The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the depth representation information SEI message applies.

When present, the depth representation information SEI message may be included in any access unit. It is recommended that, when present, the SEI message is included for the purpose of random access in an access unit in which the coded picture with nuh_layer_id equal to targetLayerId is an TRAP picture.

For an auxiliary picture with sdi_aux_id[targetLayerId] equal to AUX_DEPTH, an associated primary picture, if any, is a picture in the same access unit having sdi_aux_id[nuhLayerIdB] equal to 0 such that ScalabilityId[LayerIdxInVps[targetLayerId]][j] is equal to ScalabilityId[LayerIdxInVps[nuhLayerIdB]][j] for all values of j in the range of 0 to 2, inclusive, and 4 to 15, inclusive.

The information indicated in the SEI message applies to all the pictures with nuh_layer_id equal to targetLayerId from the access unit containing the SEI message up to but excluding the next picture, in decoding order, associated with a depth representation information SEI message applicable to targetLayerId or to the end of the CLVS of the nuh_layer_id equal to targetLayerId, whichever is earlier in decoding order.z_near_flag equal to 0 specifies that the syntax elements specifying the nearest depth value are not present in the syntax structure. z_near_flag equal to 1 specifies that the syntax elements specifying the nearest depth value are present in the syntax structure.z_far_flag equal to 0 specifies that the syntax elements specifying the farthest depth value are not present in the syntax structure. z_far_flag equal to 1 specifies that the syntax elements specifying the farthest depth value are present in the syntax structure.d_min_flag equal to 0 specifies that the syntax elements specifying the minimum disparity value are not present in the syntax structure. d_min_flag equal to 1 specifies that the syntax elements specifying the minimum disparity value are present in the syntax structure.d_max_flag equal to 0 specifies that the syntax elements specifying the maximum disparity value are not present in the syntax structure. d_max_flag equal to 1 specifies that the syntax elements specifying the maximum disparity value are present in the syntax structure.depth_representation_type specifies the representation definition of decoded luma samples of auxiliary pictures as specified in Table Y1. In Table Y1, disparity specifies the horizontal displacement between two texture views and Z value specifies the distance from a camera.

The variable maxVal is set equal to (1<<<(8+sps_bitdepth_minus8))−1, where sps_bitdepth_minus8 is the value included in or inferred for the active SPS of the layer with nuh_layer_id equal to targetLayerId.

TABLE Y1Definition of depth_representation_typedepth_representation_typeInterpretation0Each decoded luma sample value of an auxiliary picture represents aninverse of Z value that is uniformly quantized into the range of 0 tomaxVal, inclusive.When z_far_flag is equal to 1, the luma sample value equal to 0represents the inverse of ZFar (specified below). When z_near_flag isequal to 1, the luma sample value equal to maxVal represents theinverse of ZNear (specified below).1Each decoded luma sample value of an auxiliary picture representsdisparity that is uniformly quantized into the range of 0 to maxVal,inclusive.When d_min_flag is equal to 1, the luma sample value equal to 0represents DMin (specified below). When d_max_flag is equal to 1, theluma sample value equal to maxVal represents DMax (specifiedbelow).2Each decoded luma sample value of an auxiliary picture represents a Zvalue uniformly quantized into the range of 0 to maxVal, inclusive.When z_far_flag is equal to 1, the luma sample value equal to 0corresponds to ZFar (specified below). When z_near_flag is equal to 1,the luma sample value equal to maxVal represents ZNear (specifiedbelow).3Each decoded luma sample value of an auxiliary picture represents anonlinearly mapped disparity, normalized in range from 0 to maxVal,as specified by depth_nonlinear_representation_num_minus1 anddepth_nonlinear_representation_model[ i ].When d_min_flag is equal to 1, the luma sample value equal to 0represents DMin (specified below). When d_max_flag is equal to 1, theluma sample value equal to maxVal represents DMax (specifiedbelow).Other valuesReserved for future usedisparity_ref_view_id specifies the ViewId value against which the disparity values are derived.

NOTE 1—disparity_ref_view_id is present only if d_min_flag is equal to 1 or d_max_flag is equal to 1 and is useful for depth_representation_type values equal to 1 and 3.

The variables in the x column of Table Y2 are derived from the respective variables in the s, e, n and v columns of Table Y2 as follows:If the value of e is in the range of 0 to 127, exclusive, x is set equal to (−1)s*2e-31*(1+n÷2v).Otherwise (e is equal to 0), x is set equal to (−1)s*2−(30+v)*n.

NOTE 1—The above specification is similar to that found in IEC 60559:1989.

TABLE Y2Association between depth parametervariables and syntax elementsxsenvZNearZNearSignZNearExpZNearMantissaZNearManLenZFarZFarSignZFarExpZFarMantissaZFarManLenDMaxDMaxSignDMaxExpDMaxMantissaDMaxManLenDMinDMinSignDMinExpDMinMantissaDMinManLen

The DMin and DMax values, when present, are specified in units of a luma sample width of the coded picture with ViewId equal to ViewId of the auxiliary picture.

The units for the ZNear and ZFar values, when present, are identical but unspecified.depth_nonlinear_representation_num_minus1 plus 2 specifies the number of piece-wise linear segments for mapping of depth values to a scale that is uniformly quantized in terms of disparity.depth_nonlinear_representation_model[i] for i ranging from 0 to depth_nonlinear_representation_num_minus1+2, inclusive, specify the piece-wise linear segments for mapping of decoded luma sample values of an auxiliary picture to a scale that is uniformly quantized in terms of disparity. The values of depth_nonlinear_representation_model[0] and depth_nonlinear_representation_model[depth_nonlinear_representation_num_minus1+2] are both inferred to be equal to 0.

NOTE 2—When depth_representation_type is equal to 3, an auxiliary picture contains nonlinearly transformed depth samples. The variable DepthLUT[i], as specified below, is used to transform decoded depth sample values from the nonlinear representation to the linear representation, i.e., uniformly quantized disparity values. The shape of this transform is defined by means of line-segment approximation in two-dimensional linear-disparity-to-nonlinear-disparity space. The first (0, 0) and the last (maxVal, maxVal) nodes of the curve are predefined. Positions of additional nodes are transmitted in form of deviations (depth_nonlinear_representation_model[i]) from the straight-line curve. These deviations are uniformly distributed along the whole range of 0 to maxVal, inclusive, with spacing depending on the value of nonlinear_depth_representation_num_minus1.

The variable DepthLUT[i] for i in the range of 0 to maxVal, inclusive, is specified as follows:

When depth_representation_type is equal to 3, DepthLUT[dS] for all decoded luma sample values dS of an auxiliary picture in the range of 0 to maxVal, inclusive, represents disparity that is uniformly quantized into the range of 0 to maxVal, inclusive.

The syntax structure specifies the value of an element in the depth representation information SEI message.

The syntax structure sets the values of the OutSign, OutExp, OutMantissa and OutManLen variables that represent a floating-point value. When the syntax structure is included in another syntax structure, the variable names OutSign, OutExp, OutMantissa and OutManLen are to be interpreted as being replaced by the variable names used when the syntax structure is included.da_sign_flag equal to 0 indicates that the sign of the floating-point value is positive. da_sign_flag equal to 1 indicates that the sign is negative. The variable OutSign is set equal to da_sign_flag.da_exponent specifies the exponent of the floating-point value. The value of da_exponent shall be in the range of 0 to 27−2, inclusive. The value 27−1 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 27−1 as indicating an unspecified value. The variable OutExp is set equal to da_exponent.da_mantissa_len_minus1 plus 1 specifies the number of bits in the da_mantissa syntax element. The value of da_mantissa_len_minus1 shall be in the range of 0 to 31, inclusive. The variable OutManLen is set equal to da_mantissa_len_minus1+1.da_mantissa specifies the mantissa of the floating-point value. The variable OutMantissa is set equal to da_mantissa.

Alpha Channel Information SEI Message

Alpha Channel Information SEI Message Syntax

Alpha Channel Information SEI Message Semantics

The alpha channel information SEI message provides information about alpha channel sample values and post-processing applied to the decoded alpha planes coded in auxiliary pictures of type AUX_ALPHA and one or more associated primary pictures.

For an auxiliary picture with nuh_layer_id equal to nuhLayerIdA and sdi_aux_id[nuhLayerIdA] equal to AUX_ALPHA, an associated primary picture, if any, is a picture in the same access unit having sdi_aux_id[nuhLayerIdB] equal to 0 such that ScalabilityId[LayerIdxInVps[nuhLayerIdA]][j] is equal to ScalabilityId[LayerIdxInVps[nuhLayerIdB]][j] for all values of j in the range of 0 to 2, inclusive, and 4 to 15, inclusive.

When an access unit contains an auxiliary picture picA with nuh_layer_id equal to nuhLayerIdA and sdi_aux_id[nuhLayerIdA] equal to AUX_ALPHA, the alpha channel sample values of picA persist in output order until one or more of the following conditions are true:The next picture, in output order, with nuh_layer_id equal to nuhLayerIdA is output.A CLVS containing the auxiliary picture picA ends.The bitstream ends.A CLVS of any associated primary layer of the auxiliary picture layer with nuh_layer_id equal to nuhLayerIdA ends.

The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the alpha channel information SEI message applies.alpha_channel_cancel_flag equal to 1 indicates that the alpha channel information SEI message cancels the persistence of any previous alpha channel information SEI message in output order that applies to the current layer. alpha_channel_cancel_flag equal to 0 indicates that alpha channel information follows.

Let currPic be the picture that the alpha channel information SEI message is associated with. The semantics of alpha channel information SEI message persist for the current layer in output order until one or more of the following conditions are true:A new CLVS of the current layer begins.The bitstream ends.A picture picB with nuh_layer_id equal to targetLayerId in an access unit containing an alpha channel information SEI message with nuh_layer_id equal to targetLayerId is output having PicOrderCnt(picB) greater than PicOrderCnt(currPic), where PicOrderCnt(picB) and PicOrderCnt(currPic) are the PicOrderCntVal values of picB and currPic, respectively, immediately after the invocation of the decoding process for picture order count for picB.alpha_channel_use_idc equal to 0 indicates that for alpha blending purposes the decoded samples of the associated primary picture should be multiplied by the interpretation sample values of the auxiliary coded picture in the display process after output from the decoding process. alpha_channel_use_idc equal to 1 indicates that for alpha blending purposes the decoded samples of the associated primary picture should not be multiplied by the interpretation sample values of the auxiliary coded picture in the display process after output from the decoding process. alpha_channel_use_idc equal to 2 indicates that the usage of the auxiliary picture is unspecified. Values greater than 2 for alpha_channel_use_idc are reserved for future use by ITU-T|ISO/IEC. When not present, the value of alpha_channel_use_idc is inferred to be equal to 2.alpha_channel_bit_depth_minus8 plus 8 specifies the bit depth of the samples of the luma sample array of the auxiliary picture. alpha_channel_bit_depth_minus8 shall be in the range 0 to 7 inclusive. alpha_channel_bit_depth_minus8 shall be equal to bit_depth_luma_minus8 of the associated primary picture.alpha_transparent_value specifies the interpretation sample value of an auxiliary coded picture luma sample for which the associated luma and chroma samples of the primary coded picture are considered transparent for purposes of alpha blending. The number of bits used for the representation of the alpha_transparent_value syntax element is alpha_channel_bit_depth_minus8+9.alpha_opaque_value specifies the interpretation sample value of an auxiliary coded picture luma sample for which the associated luma and chroma samples of the primary coded picture are considered opaque for purposes of alpha blending. The number of bits used for the representation of the alpha_opaque_value syntax element is alpha_channel_bit_depth_minus8+9.alpha_channel_incr_flag equal to 0 indicates that the interpretation sample value for each decoded auxiliary picture luma sample value is equal to the decoded auxiliary picture sample value for purposes of alpha blending. alpha_channel_incr_flag equal to 1 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample value that is greater than Min(alpha_opaque_value, alpha_transparent_value) should be increased by one to obtain the interpretation sample value for the auxiliary picture sample and any auxiliary picture luma sample value that is less than or equal to Min(alpha_opaque_value, alpha_transparent_value) should be used, without alteration, as the interpretation sample value for the decoded auxiliary picture sample value. When not present, the value of alpha_channel_incr_flag is inferred to be equal to 0.alpha_channel_clip_flag equal to 0 indicates that no clipping operation is applied to obtain the interpretation sample values of the decoded auxiliary picture. alpha_channel_clip_flag equal to 1 indicates that the interpretation sample values of the decoded auxiliary picture are altered according to the clipping process described by the alpha_channel_clip_type_flag syntax element. When not present, the value of alpha_channel_clip_flag is inferred to be equal to 0.alpha_channel_clip_type_flag equal to 0 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample that is greater than (alpha_opaque_value−alpha_transparent_value)/2 is set equal to alpha_opaque_value to obtain the interpretation sample value for the auxiliary picture luma sample and any auxiliary picture luma sample that is less or equal than (alpha_opaque_value−alpha_transparent_value)/2 is set equal to alpha_transparent_value to obtain the interpretation sample value for the auxiliary picture luma sample. alpha_channel_clip_type_flag equal to 1 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample that is greater than alpha_opaque_value is set equal to alpha_opaque_value to obtain the interpretation sample value for the auxiliary picture luma sample and any auxiliary picture luma sample that is less than or equal to alpha_transparent_value is set equal to alpha_transparent_value to obtain the interpretation sample value for the auxiliary picture luma sample.

NOTE—When both alpha_channel_incr_flag and alpha_channel_clip_flag are equal to one, the clipping operation specified by alpha_channel_clip_type_flag should be applied first followed by the alteration specified by alpha_channel_incr_flag to obtain the interpretation sample value for the auxiliary picture luma sample.

Alpha Channel Information SEI Message

Alpha Channel Information SEI Message Syntax

Alpha Channel Information SEI Message Semantics

The alpha channel information (ACI) SEI message provides information about alpha channel sample values and post-processing applied to the decoded alpha planes coded in auxiliary pictures of type AUX_ALPHA and one or more associated primary pictures.

For an auxiliary picture with nuh_layer_id equal to nuhLayerIdA and sdi_aux_id[nuhLayerIdA] equal to AUX_ALPHA, an associated primary picture, if any, is a picture in the same access unit having sdi_aux_id[nuhLayerIdB] equal to 0 such that ScalabilityId[LayerIdxInVps[nuhLayerIdA]][j] is equal to ScalabilityId[LayerIdxInVps[nuhLayerIdB]][j] for all values of j in the range of 0 to 2, inclusive, and 4 to 15, inclusive.

When a CVS does not contain an SDI SEI message with sdi_aux_id[i] equal to 1 for at least one value of i, no picture in the CVS shall be associated with an ACI SEI message.

When an AU contains both an SDI SEI message with sdi_aux_id[i] equal to 1 for at least one value of i and an ACI SEI message, the SDI SEI message shall precede the ACI SEI message in decoding order.

When an access unit contains an auxiliary picture picA in a layer that is indicated as an alpha auxiliary layer by an SDI SEI message with nuh_layer_id equal to nuhLayerIdA and sdi_aux_id[nuhLayerIdA] equal to AUX_ALPHA, the alpha channel sample values of picA persist in output order until one or more of the following conditions are true:

The next picture, in output order, with nuh_layer_id equal to nuhLayerIdA is output.A CLVS containing the auxiliary picture picA ends.The bitstream ends.A CLVS of any associated primary layer of the auxiliary picture layer with nuh_layer_id equal to nuhLayerIdA ends.

The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the alpha channel information SEI message applies.alpha_channel_cancel_flag equal to 1 indicates that the alpha channel information SEI message cancels the persistence of any previous alpha channel information SEI message in output order that applies to the current layer. alpha_channel_cancel_flag equal to 0 indicates that alpha channel information follows.

Let currPic be the picture that the alpha channel information SEI message is associated with. The semantics of alpha channel information SEI message persist for the current layer in output order until one or more of the following conditions are true:

A new CLVS of the current layer begins.

The bitstream ends.

A picturepicB with nuh_layer_id equal to targetLayerId in an access unit containing an alpha channel information SEI message is. with nuh_layer_id equal to targetLayerId is output having PicOrderCnt(picB) greater than PicOrderCnt(currPic), where PicOrderCnt(picB) and PicOrderCnt(currPic) are the PicOrderCntVal values of picB and currPic, respectively, immediately after the invocation of the decoding process for picture order count for picB.alpha_channel_use_idc equal to 0 indicates that for alpha blending purposes the decoded samples of the associated primary picture should be multiplied by the interpretation sample values of the auxiliary coded picture in the display process after output from the decoding process. alpha_channel_use_idc equal to 1 indicates that for alpha blending purposes the decoded samples of the associated primary picture should not be multiplied by the interpretation sample values of the auxiliary coded picture in the display process after output from the decoding process. alpha_channel_use_idc equal to 2 indicates that the usage of the auxiliary picture is unspecified. Values greater than 2 for alpha_channel_use_idc are reserved for future use by ITU-T|ISO/IEC. When not present, the value of alpha_channel_use_idc is inferred to be equal to 2.alpha_channel_bit_depth_minus8 plus 8 specifies the bit depth of the samples of the luma sample array of the auxiliary picture. alpha_channel_bit_depth_minus8 shall be in the range 0 to 7 inclusive. alpha_channel_bit_depth_minus8 shall be equal to bit_depth_luma_minus8 of the associated primary picture.alpha_transparent_value specifies the interpretation sample value of an auxiliary coded picture luma sample for which the associated luma and chroma samples of the primary coded picture are considered transparent for purposes of alpha blending. The number of bits used for the representation of the alpha_transparent_value syntax element is alpha_channel_bit_depth_minus8+9.alpha_opaque_value specifies the interpretation sample value of an auxiliary coded picture luma sample for which the associated luma and chroma samples of the primary coded picture are considered opaque for purposes of alpha blending. The number of bits used for the representation of the alpha_opaque_value syntax element is alpha_channel_bit_depth_minus8+9.alpha_channel_incr_flag equal to 0 indicates that the interpretation sample value for each decoded auxiliary picture luma sample value is equal to the decoded auxiliary picture sample value for purposes of alpha blending. alpha_channel_incr_flag equal to 1 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample value that is greater than Min(alpha_opaque_value, alpha_transparent_value) should be increased by one to obtain the interpretation sample value for the auxiliary picture sample and any auxiliary picture luma sample value that is less than or equal to Min(alpha_opaque_value, alpha_transparent_value) should be used, without alteration, as the interpretation sample value for the decoded auxiliary picture sample value. When not present, the value of alpha_channel_incr_flag is inferred to be equal to 0.alpha_channel_clip_flag equal to 0 indicates that no clipping operation is applied to obtain the interpretation sample values of the decoded auxiliary picture. alpha_channel_clip_flag equal to 1 indicates that the interpretation sample values of the decoded auxiliary picture are altered according to the clipping process described by the alpha_channel_clip_type_flag syntax element. When not present, the value of alpha_channel_clip_flag is inferred to be equal to 0.alpha_channel_clip_type_flag equal to 0 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample that is greater than (alpha_opaque_value−alpha_transparent_value)/2 is set equal to alpha_opaque_value to obtain the interpretation sample value for the auxiliary picture luma sample and any auxiliary picture luma sample that is less or equal than (alpha_opaque_value−alpha_transparent_value)/2 is set equal to alpha_transparent_value to obtain the interpretation sample value for the auxiliary picture luma sample. alpha_channel_clip_type_flag equal to 1 indicates that, for purposes of alpha blending, after decoding the auxiliary picture samples, any auxiliary picture luma sample that is greater than alpha_opaque_value is set equal to alpha_opaque_value to obtain the interpretation sample value for the auxiliary picture luma sample and any auxiliary picture luma sample that is less than or equal to alpha_transparent_value is set equal to alpha_transparent_value to obtain the interpretation sample value for the auxiliary picture luma sample.

NOTE—When both alpha_channel_incr_flag and alpha_channel_clip_flag are equal to one, the clipping operation specified by alpha_channel_clip_type_flag should be applied first followed by the alteration specified by alpha_channel_incr_flag to obtain the interpretation sample value for the auxiliary picture luma sample.

Scalability Dimension Information (SDI) SEI Message

Scalability Dimension SEI Message Syntax

Scalability Dimension SEI Message Semantics

The scalability dimension SEI message provides the scalability dimension information for each layer in bitstreamInScope (defined below), such as 1) when bitstreamInScope may be a multiview bitstream, the view ID of each layer; and 2) when there may be auxiliary information (such as depth or alpha) carried by one or more layers in bitstreamInScope, the auxiliary ID of each layer.

The bitstreamInScope is the sequence of AUs that consists, in decoding order, of the AU containing the current scalability dimension SEI message, followed by zero or more AUs, including all subsequent AUs up to but not including any subsequent AU that contains a scalability dimension SEI message.sdi_max_layers_minus1 plus 1 indicates the maximum number of layers in bitstreamInScope.sdi_multiview_info_flag equal to 1 indicates that bitstreamInScope may be a multiview bitstream and the sdi_view_id_val[ ] syntax elements are present in the scalability dimension SEI message. sdi_multiview_flag equal to 0 indicates that bitstreamInScope is not a multiview bitstream and the sdi_view_id_val[ ] syntax elements are not present in the scalability dimension SEI message.sdi_auxiliary_info_flag equal to 1 indicates that there may be auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are present in the scalability dimension SEI message. sdi_auxiliary_info_flag equal to 0 indicates that there is no auxiliary information carried by one or more layers in bitstreamInScope and the sdi_aux_id[ ] syntax elements are not present in the scalability dimension SEI message.sdi_view_id_len specifies the length, in bits, of the sdi_view_id_val[i] syntax element.sdi_view_id_val[i] specifies the view ID of the i-th layer in bitstreamInScope. The length of the sdi_view_id_val[i] syntax element is sdi_view_id_len bits. When not present, the value of sdi_view_id_val[i] is inferred to be equal to 0.

The variable NumViews is derived as follows:

NOTE 3— The interpretation of auxiliary pictures associated with sdi_aux_id in the range of 128 to 159, inclusive, is specified through means other than the sdi_aux_id value.sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, for bitstreams conforming to this version of this Specification. Although the value of sdi_aux_id[i] shall be in the range of 0 to 2, inclusive, or 128 to 159, inclusive, in this version of this Specification, decoders shall allow values of sdi_aux_id[i] in the range of 0 to 255, inclusive.

Multiview Acquisition Information SEI Message

Multiview Acquisition Information SEI Message Syntax

Multiview Acquisition Information SEI Message Semantics

The multiview acquisition informationSEI message specifies various parameters of the acquisition environment. Specifically, intrinsic and extrinsic camera parameters are specified. These parameters could be used for processing the decoded views prior to rendering on a 3D display.

The following semantics apply separately to each nuh_layer_id targetLayerId among the nuh_layer_id values to which the multiview acquisition information SEI message applies.

When present, the multiview acquisition information SEI message that applies to the current layer shall be included in an access unit that contains an TRAP picture that is the first picture of a CLVS of the current layer. The information signalled in the SEI message applies to the CLVS.

When the multiview acquisition information SEI message is contained in a scalable nesting SEI message, the syntax elements sn_ols_flag and sn_all_layers_flag in the scalable nesting SEI message shall be equal to 0.

The variable numViewsMinus1 is derived as follows:If the multiview acquisition information SEI message is not included in a scalable nesting SEI message, numViewsMinus1 is set equal to 0.Otherwise (the multiview acquisition information SEI message is included in a scalable nesting SEI message), numViewsMinus1 is set equal to sn_num_layers_minus1.

Some of the views for which the multiview acquisition information is included in a multiview acquisition information SEI message may not be present.

In the semantics below, index i refers to the syntax elements and variables that apply to the layer with nuh_layer_id equal to NestingLayerId[i].

The extrinsic camera parameters are specified according to a right-handed coordinate system, where the upper left corner of the image is the origin, i.e., the (0, 0) coordinate, with the other corners of the image having non-negative coordinates. With these specifications, a 3-dimensional world point, wP=[x y z] is mapped to a 2-dimensional camera point, cP[i]=[u v 1], for the i-th camera according to:

where A[i] denotes the intrinsic camera parameter matrix, R−1[i] denotes the inverse of the rotation matrix R[i], T[i] denotes the translation vector and s (a scalar value) is an arbitrary scale factor chosen to make the third coordinate of cP[i] equal to 1. The elements of A[i], R[i] and T[i] are determined according to the syntax elements signalled in this SEI message and as specified below.intrinsic_param_flag equal to 1 indicates the presence of intrinsic camera parameters. intrinsic_param_flag equal to 0 indicates the absence of intrinsic camera parameters.extrinsic_param_flag equal to 1 indicates the presence of extrinsic camera parameters. extrinsic_param_flag equal to 0 indicates the absence of extrinsic camera parameters.intrinsic_params_equal_flag equal to 1 indicates that the intrinsic camera parameters are equal for all cameras and only one set of intrinsic camera parameters are present. intrinsic_params_equal_flag equal to 0 indicates that the intrinsic camera parameters are different for each camera and that a set of intrinsic camera parameters are present for each camera.prec_focal_length specifies the exponent of the maximum allowable truncation error for focal_length_x[i] and focal_length_y[i] as given by 2−prec_focal_length. The value of prec_focal_length shall be in the range of 0 to 31, inclusive.prec_principal_point specifies the exponent of the maximum allowable truncation error for principal_point_x[i] and principal_point_y[i] as given by 2−prec_principal_point. The value of prec_principal_point shall be in the range of 0 to 31, inclusive.prec_skew_factor specifies the exponent of the maximum allowable truncation error for skew factor as given by 2−prec_skew_factor. The value of prec_skew_factor shall be in the range of 0 to 31, inclusive.sign_focal_length_x[i] equal to 0 indicates that the sign of the focal length of the i-th camera in the horizontal direction is positive. sign_focal_length_x[i] equal to 1 indicates that the sign is negative.exponent_focal_length_x[i] specifies the exponent part of the focal length of the i-th camera in the horizontal direction. The value of exponent_focal_length_x[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified focal length.mantissa_focal_length_x[i] specifies the mantissa part of the focal length of the i-th camera in the horizontal direction. The length of the mantissa_focal_length_x[i] syntax element is variable and determined as follows:If exponent_focal_length_x[i] is equal to 0, the length is Max(0, prec_focal_length−30).Otherwise (exponent_focal_length_x[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_focal_length_x[i]+prec_focal_length−31).sign_focal_length_y[i] equal to 0 indicates that the sign of the focal length of the i-th camera in the vertical direction is positive. sign_focal_length_y[i] equal to 1 indicates that the sign is negative.exponent_focal_length_y[i] specifies the exponent part of the focal length of the i-th camera in the vertical direction. The value of exponent_focal_length_y[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified focal length.mantissa_focal_length_y[i] specifies the mantissa part of the focal length of the i-th camera in the vertical direction.

The length of the mantissa_focal_length_y[i] syntax element is variable and determined as follows:

If exponent_focal_length_y[i] is equal to 0, the length is Max(0, prec_focal_length−30).Otherwise (exponent_focal_length_y[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_focal_length_y[i]+prec_focal_length−31).sign_principal_point_x[i] equal to 0 indicates that the sign of the principal point of the i-th camera in the horizontal direction is positive. sign_principal_point_x[i] equal to 1 indicates that the sign is negative.exponent_principal_point_x[i] specifies the exponent part of the principal point of the i-th camera in the horizontal direction. The value of exponent_principal_point_x[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified principal point.mantissa_principal_point_x[i] specifies the mantissa part of the principal point of the i-th camera in the horizontal direction. The length of the mantissa_principal_point_x[i] syntax element in units of bits is variable and is determined as follows:If exponent_principal_point_x[i] is equal to 0, the length is Max(0, prec_principal_point−30).Otherwise (exponent_principal_point_x[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_principal_point_x[i]+prec_principal_point−31).sign_principal_point_y[i] equal to 0 indicates that the sign of the principal point of the i-th camera in the vertical direction is positive. sign_principal_point_y[i] equal to 1 indicates that the sign is negative.exponent_principal_point_y[i] specifies the exponent part of the principal point of the i-th camera in the vertical direction. The value of exponent_principal_point_y[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified principal point.mantissa_principal_point_y[i] specifies the mantissa part of the principal point of the i-th camera in the vertical direction. The length of the mantissa_principal_point_y[i] syntax element in units of bits is variable and is determined as follows:If exponent_principal_point_y[i] is equal to 0, the length is Max(0, prec_principal_point−30).Otherwise (exponent_principal_point_y[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_principal_point_y[i]+prec_principal_point−31).sign_skew_factor[i] equal to 0 indicates that the sign of the skew factor of the i-th camera is positive.sign_skew_factor[i] equal to 1 indicates that the sign is negative.exponent_skew_factor[i] specifies the exponent part of the skew factor of the i-th camera. The value of exponent_skew_factor[i] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified skew factor.mantissa_skew_factor[i] specifies the mantissa part of the skew factor of the i-th camera. The length of the mantissa_skew_factor[i] syntax element is variable and determined as follows:If exponent_skew_factor[i] is equal to 0, the length is Max(0, prec_skew_factor−30).Otherwise (exponent_skew_factor[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_skew_factor[i]+prec_skew_factor−31).

The intrinsic matrix A[i] for i-th camera is represented by:

[focalLengthX[i]skewFactor[i]principalPointX[i]0focalLengthY[i]principalPointY[i]001](X)prec_rotation_param specifies the exponent of the maximum allowable truncation error for r[i][j][k] as given by 2−prec_rotation_param. The value of prec_rotation_param shall be in the range of 0 to 31, inclusive.prec_translation_param specifies the exponent of the maximum allowable truncation error for t[i][j] as given by 2−prec_translation_param. The value of prec_translation_param shall be in the range of 0 to 31, inclusive.sign_r[i][j][k] equal to 0 indicates that the sign of (j, k) component of the rotation matrix for the i-th camera is positive. sign_r[i][j][k] equal to 1 indicates that the sign is negative.exponent_r[i][j][k] specifies the exponent part of (j, k) component of the rotation matrix for the i-th camera. The value of exponent_r[i][j][k] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified rotation matrix.mantissa_r[i][j][k] specifies the mantissa part of (j, k) component of the rotation matrix for the i-th camera. The length of the mantissa_r[i][j][k] syntax element in units of bits is variable and determined as follows:If exponent_r[i] is equal to 0, the length is Max(0, prec_rotation_param−30).Otherwise (exponent_r[i] is in the range of 0 to 63, exclusive), the length is Max(0, exponent_r[i]+prec_rotation_param−31).

The rotation matrix R[i] for i-th camera is represented as follows:

[rE[i][0][0]rE[i][0][1]rE[i][0][2]rE[i][1][0]rE[i][1][1]rE[i][1][2]rE[i][2][0]rE[i][2][1]rE[i][2][2]](X)sign_t[i][j] equal to 0 indicates that the sign of the j-th component of the translation vector for the i-th camera is positive. sign_t[i][j] equal to 1 indicates that the sign is negative.exponent_t[i][j] specifies the exponent part of the j-th component of the translation vector for the i-th camera. The value of exponent_t[i][j] shall be in the range of 0 to 62, inclusive. The value 63 is reserved for future use by ITU-T|ISO/IEC. Decoders shall treat the value 63 as indicating an unspecified translation vector.mantissa_t[i][j] specifies the mantissa part of the j-th component of the translation vector for the i-th camera. The length v of the mantissa_t[i][j] syntax element in units of bits is variable and is determined as follows:If exponent_t[i] is equal to 0, the length v is set equal to Max(0, prec_translation_param−30).Otherwise (0<exponent_t[i]<63), the length v is set equal to Max(0, exponent_t[i]+prec_translation_param−31).

The translation vector T[i] for the i-th camera is represented by:

The association between the camera parameter variables and corresponding syntax elements is specified by Table ZZ. Each component of the intrinsic and rotation matrices and the translation vector is obtained from the variables specified in Table ZZ as the variable x computed as follows:If e is in the range of 0 to 63, exclusive, x is set equal to (−1)s*2e-31*(1+n÷2v).Otherwise (e is equal to 0), x is set equal to (−1)s*2−(30+v)*n.

NOTE—The above specification is similar to that found in IEC 60559:1989.

TABLE ZZAssociation between camera parameter variables and syntax elements.xsenfocalLengthX[ i ]sign_focal_length_x[ i ]exponent_focal_length_x[ i ]mantissa_focal_length_x[ i ]focalLengthY[ i ]sign_focal_length_y[ i ]exponent_focal_length_y[ i ]mantissa_focal_length_y[ i ]principalPointX[ i ]sign_principal_point_x[ i ]exponent_principal_point_x[ i ]mantissa_principal_point_x[ i ]principalPointY[i]sign_principal_point_y[ i ]exponent_principal_point_y[ i ]mantissa_principal_point_y[ i ]skewFactor[ i ]sign_skew_factor[ i ]exponent_skew_factor[ i ]mantissa_skew_factor[ i ]rE[ i ][ j ][ k ]sign_r[ i ][ j ][ k ]exponent_r[ i ][ j ][ k ]mantissa_r[ i ][ j ][ k ]tE[ i ][ j ]sign_t[ i ][ j ]exponent_t[ i ][ j ]mantissa_t[ i ][ j ]

FIG.4is a block diagram showing an example video processing system400in which various techniques disclosed herein may be implemented. Various implementations may include some or all of the components of the video processing system400. The video processing system400may include input402for 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 input402may 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 video processing system400may include a coding component404that may implement the various coding or encoding methods described in the present document. The coding component404may reduce the average bitrate of video from the input402to the output of the coding component404to 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 component404may be either stored, or transmitted via a communication connected, as represented by the component406. The stored or communicated bitstream (or coded) representation of the video received at the input402may be used by the component408for generating pixel values or displayable video that is sent to a display interface410. 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 SATA (serial advanced technology attachment), Peripheral Component Interconnect (PCI), Integrated Drive Electronics (IDE) interface, and the like. The techniques described in the present document 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.5is a block diagram of a video processing apparatus500. The apparatus500may be used to implement one or more of the methods described herein. The apparatus500may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on. The apparatus500may include one or more processors502, one or more memories504and video processing hardware506(a.k.a., video processing circuitry). The processor(s)502may be configured to implement one or more methods described in the present document. The memory (memories)504may be used for storing data and code used for implementing the methods and techniques described herein. The video processing hardware506may be used to implement, in hardware circuitry, some techniques described in the present document. In some embodiments, the hardware506may be partly or completely located within the processor502, e.g., a graphics processor.

FIG.6is a block diagram that illustrates an example video coding system600that may utilize the techniques of this disclosure. As shown inFIG.6, the video coding system600may include a source device610and a destination device620. Source device610generates encoded video data which may be referred to as a video encoding device. Destination device620may decode the encoded video data generated by source device610which may be referred to as a video decoding device.

Source device610may include a video source612, a video encoder614, and an input/output (I/O) interface616.

Video source612may 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 encoder614encodes the video data from video source612to 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 interface616may include a modulator/demodulator (modem) and/or a transmitter. The encoded video data may be transmitted directly to destination device620via I/O interface616through network630. The encoded video data may also be stored onto a storage medium/server640for access by destination device620.

Destination device620may include an I/O interface626, a video decoder624, and a display device622.

I/O interface626may include a receiver and/or a modem. I/O interface626may acquire encoded video data from the source device610or the storage medium/server640. Video decoder624may decode the encoded video data. Display device622may display the decoded video data to a user. Display device622may be integrated with the destination device620, or may be external to destination device620which may be configured to interface with an external display device.

Video encoder614and video decoder624may 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.7is a block diagram illustrating an example of video encoder700, which may be video encoder614in the video coding system600illustrated inFIG.6.

Video encoder700may be configured to perform any or all of the techniques of this disclosure. In the example ofFIG.7, video encoder700includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of video encoder700. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

The functional components of video encoder700may include a partition unit701, a prediction unit702which may include a mode selection unit703, a motion estimation unit704, a motion compensation unit705and an intra prediction unit706, a residual generation unit707, a transform unit708, a quantization unit709, an inverse quantization unit710, an inverse transform unit711, a reconstruction unit712, a buffer713, and an entropy encoding unit714.

In other examples, video encoder700may include more, fewer, or different functional components. In an example, prediction unit702may 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 unit704and motion compensation unit705may be highly integrated, but are represented in the example ofFIG.7separately for purposes of explanation.

Partition unit701may partition a picture into one or more video blocks. Video encoder614and video decoder624ofFIG.6may support various video block sizes.

Mode selection unit703may 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 unit707to generate residual block data and to a reconstruction unit712to reconstruct the encoded block for use as a reference picture. In some examples, mode selection unit703may select a combination of intra and inter prediction (CLIP) mode in which the prediction is based on an inter prediction signal and an intra prediction signal. Mode selection unit703may 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 unit704may generate motion information for the current video block by comparing one or more reference frames from buffer713to the current video block. Motion compensation unit705may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer713other than the picture associated with the current video block.

Motion estimation unit704and motion compensation unit705may 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. I-slices (or I-frames) are the least compressible but don't require other video frames to decode. S-slices (or P-frames) can use data from previous frames to decompress and are more compressible than I-frames. B-slices (or B-frames) can use both previous and forward frames for data reference to get the highest amount of data compression.

In other examples, motion estimation unit704may perform bi-directional prediction for the current video block, motion estimation unit704may 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 unit704may 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 unit704may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. Motion compensation unit705may 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 unit704may output a full set of motion information for decoding processing of a decoder.

In some examples, motion estimation unit704may not output a full set of motion information for the current video. Rather, motion estimation unit704may signal the motion information of the current video block with reference to the motion information of another video block. For example, motion estimation unit704may 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 unit704may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder624that the current video block has the same motion information as another video block.

As discussed above, video encoder614may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder614include advanced motion vector prediction (AMVP) and merge mode signaling.

Intra prediction unit706may perform intra prediction on the current video block. When intra prediction unit706performs intra prediction on the current video block, intra prediction unit706may 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.

In other examples, there may be no residual data for the current video block, for example in a skip mode, and residual generation unit707may not perform the subtracting operation.

After transform unit708generates a transform coefficient video block associated with the current video block, quantization unit709may 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 unit710and inverse transform unit711may 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 unit712may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the prediction unit702to produce a reconstructed video block associated with the current block for storage in the buffer713.

After reconstruction unit712reconstructs the video block, loop filtering operation may be performed to reduce video blocking artifacts in the video block.

Entropy encoding unit714may receive data from other functional components of the video encoder700. When entropy encoding unit714receives the data, entropy encoding unit714may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.

FIG.8is a block diagram illustrating an example of video decoder800, which may be video decoder624in the video coding system600illustrated inFIG.6.

The video decoder800may be configured to perform any or all of the techniques of this disclosure. In the example ofFIG.8, the video decoder800includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of the video decoder800. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

In the example ofFIG.8, video decoder800includes an entropy decoding unit801, a motion compensation unit802, an intra prediction unit803, an inverse quantization unit804, an inverse transformation unit805, a reconstruction unit806, and a buffer807. Video decoder800may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder614(FIG.6).

Entropy decoding unit801may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data). Entropy decoding unit801may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit802may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit802may, for example, determine such information by performing the AMVP and merge mode signaling.

Motion compensation unit802may use interpolation filters as used by video encoder614during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit802may determine the interpolation filters used by video encoder614according to received syntax information and use the interpolation filters to produce predictive blocks.

Intra prediction unit803may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit804inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit801. Inverse transform unit805applies an inverse transform.

Reconstruction unit806may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit802or intra prediction unit803to 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 buffer807, which provides reference blocks for subsequent motion compensation/intra prediction and also produces decoded video for presentation on a display device.

FIG.9is a method900for coding video data according to an embodiment of the disclosure. The method900may be performed by a coding apparatus (e.g., an encoder) having a processor and a memory. The method900may be implemented when using SEI messages to convey information in a bitstream.

In block902, the coding apparatus uses a scalability dimension information (SDI) supplemental enhancement information (SEI) message to indicate an SDI view identifier length minus L syntax element. The SDI SEI message is a type of SEI message like, for example, the SEI message in the bitstream300ofFIG.3. The SDI view identifier length minus L syntax element is a type of syntax element like, for example, the syntax elements324in the bitstream300ofFIG.3. The SEI message, including the SDI SEI message, may carry any of the elements of syntax disclosed herein.

In block904, the coding apparatus converts between a video media file and the bitstream based on the SDI SEI message.

When implemented in an encoder, converting includes receiving a media file (e.g., a video unit) and encoding an SEI message into a bitstream. When implemented in a decoder, converting includes receiving the bitstream including the SEI message, and decoding the SEI message in the bitstream to generate the video media file.

In an embodiment, the SDI view identifier length minus L syntax element is configured to prevent a length of an SDI view identifier value syntax element, which specifies a view identifier of an i-th layer in a bitstream, from being zero. In an embodiment, L is equal to 1. In an embodiment, the SDI view identifier length minus L syntax element is designated sdi_view_id_len_minus1. In an embodiment, the SDI view identifier value syntax element is designated sdi_view_id_val[i]. In an embodiment, the SDI view identifier length minus L syntax element, plus one, specifies the length of the SDI view identifier value syntax element.

In an embodiment, the SDI view identifier length minus L syntax element is coded as an unsigned integer using N bits. By way of example, an unsigned integer is an integer (e.g., a whole number) that does not have a sign (e.g., positive or negative) associated therewith. In an embodiment, N is equal to 4.

In an embodiment, the SDI view identifier length minus L syntax element is coded as a fixed-pattern bitstring using N bits, a signed integer using N bits, a truncated binary, a signed integer K-th order Exp-Golomb-coded syntax element where K is equal to 0, or an unsigned integer M-th order Exp-Golomb-coded syntax element where M is equal to 0. A bitstring is an array data structure that compactly stores bits. A fixed-pattern bitstring is an array data structure having a fixed pattern. A signed integer is an integer (e.g., a whole number) that has a sign (e.g., positive or negative) associated therewith. Truncated binary, or truncated binary encoding, is an entropy encoding typically used for uniform probability distributions with a finite alphabet. An exponential-Golomb code (Exp-Golomb code) is a type of universal code.

In an embodiment, the bitstream is a bitstream in scope. In an embodiment, the bitstream in scope is a sequence of access units (AUs) that consists, in decoding order, of an initial AU containing the SDI SEI message followed by zero or more subsequent AUs up to, but not including, any subsequent AU that contains another SDI SEI message.

In an embodiment, a multiview information SEI message and an auxiliary information SEI message are not present in a coded video sequence (CVS) unless the SDI SEI message is present in the CVS.

In an embodiment, the multiview information SEI message comprises a multiview acquisition information SEI message. In an embodiment, the auxiliary information SEI message comprises a depth representation information SEI message. In an embodiment, the auxiliary information SEI message comprises an alpha channel information SEI message.

In an embodiment, one or more of an SDI multiview information flag (e.g., sdi_multiview_info flag) and an SDI auxiliary information flag (e.g., sdi_auxiliary_info_flag) are equal to 1 when the multiview information SEI message or the auxiliary information SEI message are present in the bitstream. A flag is a variable or single-bit syntax element that can take one of the two possible values: 0 and 1.

In an embodiment, the multiview information SEI message comprises a multiview acquisition information SEI message, and the multiview acquisition information SEI message is not scalable-nested. A scalable-nested SEI message is an SEI message within a scalable nesting SEI message. A scalable nesting SEI message is a message that contains a plurality of scalable-nested SEI messages that correspond to one or more output layer sets or one or more layers in a multi-layer bitstream.

In an embodiment, an SEI message in the bitstream and having a payload type equal to 179 is constrained from being included in a scalable nesting SEI message. In an embodiment, an SEI message in the bitstream and having a payload type equal to 3, 133, 179, 180, or 205 is constrained from being included in a scalable nesting SEI message.

In an embodiment, the method900may utilize or incorporate one or more of the features or processes of the other methods disclosed herein.

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

The following solutions show example embodiments of techniques discussed in the present disclosure (e.g., Example 1).1. A method of video processing, comprising: performing a conversion between a video and a bitstream of the video; wherein the bitstream conforms to a format rule; wherein the format rule specifies that a syntax element indicates a length of view identifier syntax elements minus L, where L is an integer.2. The method of claim1, wherein the syntax element is coded as an unsigned integer using N bits.3. The method of any of claims1-2, wherein L is a positive integer.4. The method of claim1, wherein L=0, and wherein the syntax element is disallowed to have a zero value.5. A method of video processing, comprising: performing a conversion between a video comprising multiple layers and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that the bitstream includes an auxiliary layer that is associated with one or more associated layers of the video.6. The method of claim5, wherein the format rule further specifies whether or how the bitstream includes one or more syntax elements indicative of a relationship between the auxiliary layer and the one or more associated layers, wherein the one or more syntax elements are included in a scalability dimension supplemental enhancement information syntax structure.7. The method of claim6, wherein the format rule specifies that the one or more associated layers are indicated by corresponding layer identifiers (IDs).8. The method of claim6, wherein the format rule specifies that the one or more associated layers are indicated by corresponding layer indices.9. The method of any of claims5-8, wherein the format rule specifies that the bitstream includes one or more syntax elements indicating whether the auxiliary layer is applicable to the one or more associated layers.10. The method of claim9, wherein the one or more syntax elements comprise a syntax element indicating that the auxiliary layer is applicable to all of the one or more associated layers.11. The method of claim9, wherein the format rule specifies that a syntax element is included for each associated layer indicating whether the auxiliary layer is applicable to a corresponding associated layer.12. The method of claim11, wherein the syntax element indicates all primary layers associated with the auxiliary layer.13. The method of claim11, wherein the syntax element indicates all primary layers associated with the auxiliary layer and having a layer index smaller than that of the auxiliary layer.14. The method of claim11, wherein the syntax element indicates all primary layers associated with the auxiliary layer and having a layer index greater than that of the auxiliary layer.15. The method of any of claims11-14, wherein the syntax element is a flag.16. The method of claim6, wherein the format rule specifies that the bitstream does not include an explicit syntax element indicating applicability of the auxiliary layer to the one or more associated layers and the applicability is derived during the conversion.17. The method of claim16, wherein the format rule specifies that the associated layers for the auxiliary layers have a layer ID that is equal to a layer ID of the auxiliary layer plus N1, N2 . . . Nk, where k is an integer and no two Ni are equal to each other for i=1, . . . k.18. The method of claim17, wherein k=1 and N1 is one of 1, −1, 2 or −2.19. The method of claim17, wherein k is greater than 1.20. The method of claim19, wherein k is equal to 2 and N1=1, N2=2.21. The method of claim5, wherein the format rule further specifies that the bitstream omits one or more syntax elements indicative of a relationship between the auxiliary layer and the one or more associated layers, and wherein the relationship is derived based on pre-determined rules.22. The method of claim5, wherein the format rule further specifies that the bitstream includes one or more syntax elements indicative of a relationship between the auxiliary layer and the one or more associated layers, wherein the one or more syntax elements are included in an auxiliary information supplemental enhancement information syntax structure.23. The method of any of claims5-22, wherein the format rule specifies that a syntax element is included in the bitstream indicative of a number of associated layers of auxiliary pictures of a layer.24. The method of any of claims5-22, wherein the format rule specifies that a syntax element is included in the bitstream indicative of a number of associated layers of auxiliary pictures of a layer or associated layers of auxiliary pictures in case that a condition is met.25. The method of claim24, wherein the condition comprises that an i-th layer in the bitstreamInScope includes auxiliary pictures.26. A method of video processing, comprising: performing a conversion between a video comprising multiple video layers and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that a coded video sequence of the bitstream included a multiview supplemental enhancement information (SEI) message or an auxiliary information SEI message responsive to whether a scalability dimension information SEI message is included in a coded video sequence.27. The method of claim26, wherein the format rule specifies that the multiview information SEI message refers to a multiview acquisition information SEI message.28. The method of any of claims26-27, wherein the format rule specifies that the auxiliary information SEI message refers to a depth representation information SEI message or an alpha channel information SEI message.29. A method of video processing, comprising: performing a conversion between a video comprising multiple video layers and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that responsive to a multiview or an auxiliary information supplemental enhancement information (SEI) message being present in the bitstream, at least one of a first flag indicating a presence of multiview information or a second flag indicating presence of auxiliary information in a scalability dimension information SEI message is equal to 1.30. A method of video processing, comprising: performing a conversion between a video comprising multiple video layers and a bitstream of the video, wherein the bitstream conforms to a format rule, wherein the format rule specifies that a multiview acquisition information supplemental enhancement information message included in the bitstream is not scalable-nested or included in a scalable nesting supplemental enhancement information message.31. The method of any of claims1-30, wherein the conversion comprises generating the video from the bitstream or generating the bitstream from the video.32. A method of storing a bitstream on a computer-readable medium, comprising generating a bitstream according to a method recited in any one or more of claims1-31and storing the bitstream on the computer-readable medium.33. A computer-readable medium having a bitstream of a video stored thereon, the bitstream, when processed by a processor of a video decoder, causing the video decoder to generate the video, wherein the bitstream is generated according to a method recited in one or more of claims1-31.34. A video decoding apparatus comprising a processor configured to implement a method recited in one or more of claims1to31.35. A video encoding apparatus comprising a processor configured to implement a method recited in one or more of claims1to31.36. A computer program product having computer code stored thereon, the code, when executed by a processor, causes the processor to implement a method recited in any of claims1to31.37. A computer readable medium on which a bitstream complying to a bitstream format that is generated according to any of claims1to31.38. A method, an apparatus, a bitstream generated according to a disclosed method or a system described in the present document.