Signalling and specifying verification substream association in the digitally signed content SEI messages

Abstract

A mechanism for processing video data is disclosed The mechanism includes determining a list of non- video coding layer (non-VCL) network abstraction layer (NAL) unit types (NonVclDigitallySignedNalUnitsList) signalled in a digitally signed content (DSC) supplemental enhancement information (SEI) message. A conversion is performed between a visual media data and a bitstream based on the DSCI SEI message.

Description

SIGNALLING AND SPECIFYING VERIFICATION SUBSTREAM ASSOCIATION IN THE DIGITALLY SIGNED CONTENT SEI MESSAGES CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority to and benefits of U.S. Provisional Patent Application No.63 / 773,989 filed on March 18, 2025, which is herein incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates to generation, storage, and consumption of digital audio video media information in a file formal.BACKGROUND

[0003] Digital video accounts for the largest bandwidth used on the Internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, the bandwidth demand for digital video usage is likely to continue to grow.SUMMARY

[0004] A first aspect relates to a method for processing video data comprising: determining a list of nonvideo coding layer (non-VCL) network abstraction layer (NAL) unit types (NonVclDigilallySignedNidUnitsList) signalled in a Digitally Signed Content (DSC) supplemental enhancement information (SEI) message; and performing a conversion between a visual media data and a bitstream based on the DSC SEI message.

[0005] A second aspect relates to an apparatus for processing video data comprising: a processor; and a non-transitory' memory' with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform any of the preceding aspects.

[0006] A third aspect relates to non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of the preceding aspects.

[0007] A fourth aspect relates to a non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining a list of non-video coding layer (non-VCL) network abstraction layer (NAL) unit types (NonVclDigitallySignedNalUnitsList) signalled in a Digitally Signed Content (DSC) supplemental enhancement information (SEI) message; and generating a bitstream based on the determining.

[0008] A fifth aspect relates to a method for storing bitstream of a video comprising: determining a list of non-video coding layer (non-VCL) network abstraction layer (NAL) unit types (NonVclDigitallySignedNalUnitsList) signalled in a Digitally Signed Content (DSC) supplemental enhancement information (SEI) message; generating a bitstream based on the determining; and storing the bitstream in a non-transitor ' computer-readable recording medium.

[0009] A sixth aspect relates to a method, apparatus, or system described in the present disclosure.

[0010] For the purpose of clarity, any one of the foregoing embodiments may be combined with any one or more of the other foregoing embodiments to create a new embodiment within the scope of the present disclosure.

[0011] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0013] FIG. 1 is a block diagram showing an example video processing system.

[0014] FIG. 2 is a block diagram of an example video processing apparatus.

[0015] FIG. 3 is a flowchart for an example method of video processing.

[0016] FIG. 4 is a block diagram that illustrates an example video coding system.

[0017] FIG. 5 is a block diagram that illustrates an example encoder.

[0018] FIG. 6 is a block diagram that illustrates an example decoder.

[0019] FIG. 7 is a schematic diagram of an example encoder.DETAILED DESCRIPTION

[0020] It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and / or methods may be implemented using any number of techniques, whether currently known or yet to be developed. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0021] Section headings are used in the present disclosure for ease of understanding and do not limit the applicability of techniques and embodiments disclosed in each section only to that section. Furthermore, H.266 terminology is used in some description only for ease of understanding and not for limiting scope of the disclosed embodiments. As such, the embodiments described herein are applicable to other video codec protocols and designs also. In the present disclosure, editing changes are shown to text by triple brackets indicating cancelled text (i.c., [[[a]]] indicates that ‘a’ is deleted) and double braces indicating added text (i.c., {{a}} indicates that ‘a’ is added), with respect to the Versatile Video Coding (VVC) specification.1. Initial discussion

[0022] This disclosure is related to image / video coding technologies. Specifically, this disclosure is related to signalling and specifying verification substream association in the digitally signed content SET messages, including the digitally signed content initialization SEI message, the digitally signed content selection SEImessage, and the digitally signed content verification SEI message. The ideas may be applied individually or in various combinations, for video bitstreams coded by any codec, e.g., the versatile video coding (VVC) standard and / or the versatile supplemental enhancement information (VSEI) messages for coded video bitstreams standard.2. Abbreviations

[0023] Adaptation parameter set (APS), access unit (AU), coded layer video sequence (CLVS), coded layer video sequence start (CLVSS), cyclic redundancy check (CRC), coded video sequence (CVS), digitally signed content initialization (DSCI), digitally signed content selection (DSCS), digitally signed content verification (DSCV), finite impulse response (FIR), intra random access point (IRAP), network abstraction layer (NAL), neural-network post-processing filter (NNPF), neural-network post-filter activation (NNPFA), neural-network post-filter characteristics (NNPFC), picture parameter set (PPS), picture unit (PU), random access skipped leading (RASL) picture, supplemental enhancement information (SEI), step-wise temporal sublayer access (STSA), uniform resource identifier (URI), video coding layer (VCL), versatile supplemental enhancement information as described in Rec. ITU-T H.274 | ISO / IEC 23002-7 (VSEI), video usability information (VUI), versatile video coding as described in Rec. ITU-T H.266 | ISO / IEC 23090-3 (VVC)3. Further discussion3.1 Video coding standards

[0024] Video coding standards have evolved primarily through the development of International Telecommunication Union (ITU) telecommunication standardization sector (ITU-T) and International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC) standards. The ITU-T produced H.261 and H.263, ISO / IEC produced motion 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) [1] standards. Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized. To explore video coding technologies beyond high efficiency video coding (HEVC), the Joint Video Exploration Team (JVET) was founded by video coding experts group (VCEG) and MPEG. Further, methods have been adopted by JVET and put into the reference software named Joint Exploration Model (JEM) [2]. The JVET was later renamed to be the Joint Video Experts Team (JVET) when the Versatile Video Coding (VVC) project officially started. VVC [3] is a coding standard targeting a 50% bitrate reduction as compared to HEVC.

[0025] The Versatile Video Coding (VVC) standard (ITU-T H.266 | ISO / IEC 23090-3) [3] and the associated Versatile Supplemental Enhancement Information for coded video bitstreams (VSEI) standard (ITU-T H.274 | ISO / IEC 23002-7) [4] are designed for use in a maximally broad range of applications, including both the simple uses such as television broadcast, video conferencing, or playback from storage media, and also 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.

[0026] The Essential Video Coding (EVC) standard (ISO / IEC 23094-1) is another video coding standard under development by MPEG.3.2 SEI messages in general and in VVC and VSEI

[0027] SET messages assist in processes related to decoding, display or other purposes. However, SET messages are not required for constructing the luma or chroma samples by the decoding process. Conforming decoders are not required to process this information for output order conformance. Some SEI messages are required for checking bitstream conformance and for output timing decoder conformance. Other SEI messages are not required for checking bitstream conformance.

[0028] Annex D of VVC specifies syntax and semantics for SEI message payloads for some SEI messages, and specifies the use of the SEI messages and VUI parameters for which the syntax and semantics are specified in ITU-T H.274 | ISO / IEC 23002-7.3.3. Digitally Signed Content (DSC) SEI messages

[0029] In an example, a digitally signed content initialization (DSCI) SEI message, a digitally signed content selection (DSCS) SEI message, and a digitally signed content verification (DSCV) SEI message are specified. These three SEI messages are collectively referred to as the DSC SEI messages.

[0030] An example implementation of the DSC SET messages is as follows.8.38 Digitally signed content initialization SEI message8.38.1 Digitally signed content initialization SEI message syntax8.38.2 Digitally signed content initialization SEI message semantics[00311 Use of this SEI message requires the definition of the following:- A list of non-VCL NAL unit type identifiers nonVclDigitallySignedNalUnitsList.

[0032] The digitally signed content initialization SEI message, digitally signed content selection SEI message, and digitally signed content verification SEI message provide a mechanism for verifying that the coded video has been produced by a content provider that identifies itself via the digital certificate that is referenced in the digitally signed content initialization SEI message. This SEI message also provides information about the secure hash algorithm used for calculating message digests, which are used together with the digital signature present in digitally signed content verification SEI messages to verify the trustworthiness of non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units present in the coded video sequence. It further provides information about the digital signature algorithm used and the public key of the content provider. The digitally signed content initialization SEI message may provide the public key of the content provider either by providing an URI that identifies a trust record that contains the certificate of the content provider or by providing an URI that directly identifies the certificate.

[0033] When a digitally signed content initialization SEI message is present in any AU of a CVS, all of the following shall be true:- A digitally signed content initialization SEI message shall be present in the first IDR, CRA and GDR PU present in any AU in the CVS.- The digitally signed content initialization SEI message shall precede all non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units of the AU. - There shall be present at most one digitally signed content initialization SEI message having a particular value of dsci_id in an AU.

[0034] The digitally signed content initialization SEI message applies to the current coded picture and all following coded pictures until one or more of the following conditions are true:- The bitstream ends.- A new CVS begins.- A new digitally signed content initialization SEI message is received.

[0035] When a digitally signed content initialization SEI message is present in an AU of a CVS, a digitally signed content verification SEI message shall be present for each of the substreams that a NAL unit is assigned to. The signed content verification SEI message shall be present in the bitstream before one or more of the following conditions are true:- The bitstream ends.A new CVS begins.- A new digitally signed content initialization SEI message is received.

[0036] dsci_id contains an identifying number that may be used to identify a mechanism for verifying that the coded video has been produced by a content provider.

[0037] All digitally signed content verification SEI message having a particular value of dsci_id that apply to the same CLVS shall have the same content, dsci hash method type indicates the secure hash algorithm that is used to calculate message digests for subsets of non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units of the coded video sequence. Based on these message digests and the digital signatures present in digitally signed content verification SEI messages, a decoder can verify that the coded video was produced by the content originator indicated by the syntax elements dsci_key_source_uri, dsci_use_key_register_idx_flag and, if dsci_use_key_register_idx_flag flag is equal to 1, dsci_key_register_idx. The supported values for the syntax element dsci_hash_method_type, the block size used for calculating the message digest, and the size of the calculated message digests are specified. Values of dsci_hash_method_type that are not listed in the Table XXX are reserved for future use by ITU-T | ISO / IEC and shall not be present in payload data conforming to this version of this Specification. Decoders shall ignoretrustworthy initialization SEI messages that contain reserved values for dsci_hash_method_type. The secure hash algorithms listed in Table XXX are specified in the “Secure Hash Standard” NIST FIPS PUB 180-4.Table XXX - Supported values of dsci_hash_method_type

[0038] dsci_key_source_uri contains a URI with syntax and semantics. If dsci key retrieval mode ide is equal to 0, dsci_key_source_uri specifies a trust record. If dsci_key_retrieval_mode_idc is equal to 1, the following applies:- If dsci_use_key_regisler_idx_Hag is equal to 0, the URI identifies the certificate of the content provider that can be used for verifying the signatures present in following digitally signed content verification SEI messages;- Otherwise (if dsci_use_key_register_idx_flag is equal to 1), the URI identifies a register of certificates and the certificate of the content provider that can be used for verifying the signatures present in following digitally signed content verification SEI messages as indicated by dsci_key_register_idx.

[0039] dsci_num_verification_substreams_minusl plus 1 indicates the number of substreams for which message digests are calculated and signatures may be present in following digitally signed content verification SEI messages. Tire value of dsci_num_verification_substreams_minusl shall be in the range of 0 to 255, inclusive. The variable NumVerificationSubstream is derived as:NumVerificationSubstream = dsci_num_verification_substreams_minusl + 1.

[0040] dsci_ref_substream_flag[ i ][ j ] equal to 1 specifies that the i-th substream depends on the j-th substream. dsci_ref_substream_flag[ i ][ j ] equal to 0 specifies that the i-th substream does not depend on the j-th substream.

[0041] When not present, the value of dsci_ref_substream_flag[ i ][ j ] is inferred to be equal to 0.

[0042] DscRefSubstreamId[ i ][ refldx ], DscNumRefSubstream[ i ] and IndependentNonBaseSubstreams are derived as follows:IndependentNonBaseSubstreams = 0for( i = 0; i <= dsci num verification substreams minus 1; i++ ) {DscNumRefSubstreamf i ] = 0for(j = 0, refldx = 0, j < i ; j++ )if( dsci_ref_substream_flag[ i ][ j ] ) {DscRefSubstreamTd[ i ][ refldx ++ ] = jDscNumRefSLibslreams[ i ]++if (i > 0 && DscNumRefSubstreams[ i ] = = 0)IndependentNonBaseSubstreams = 1}

[0043] When dsci ref SLibslreani flag [ i ][ j ] is equal to 1 and dsci_ref_substream[ j ][ k ] is equal to 1 for any values of j less than i and k less than j , dsci_ref_substream[ i ] [ k ] shall be equal to 1.

[0044] dsci key retrieval mode ide equal to 0 indicates that the URI contained in dsci key source uri specifies a trust record. dsci_key_retrieval_mode_idc equal to 1 indicates that the URI contained in dsci_key_source_uri and, when present, dsci_key_register_idx specify a certificate. In this version of this Specification dsci_key_retrieval_mode_idc shall be in the range of 0 to 1. Decoders shall also allow other values of dsci_key_retrieval_mode_idc, but shall ignore the content of the digitally signed content initialization SEI message, associated digitally signed content selection SEI messages and associated digitally signed content verification SEI messages.

[0045] dsci_use_key_register_idx_flag equal to 1 indicates that the URI contained in dsci_key_source_uri specifies a register of certificates and the syntax element dsci key register idx is present in the SEI message, dsci use key register idx flag equal to 0 indicates that the URI contained in dsci key source uri specifies a certificate and the syntax element dsci_key_register_idx is not present in the SEI message.

[0046] When dsci_key_retrieval_mode_idc is equal to 0, the media asset for which the last trust manifest within the trust record provides content binding is the digitally signed content initialization SEI message. The following constraints apply to the trust record identified by the dsci_key_source_uri:- The last trust manifest within the trust record shall contain exactly one hard binding data hash assertion with a label equal to c2pa.hash.data.- The schema for data hash assertion is defined by the data-hash-map rule in the following CDDL Definition:- The exclusion range specifying the data in the digitally signed content initialization SEI message that is excluded when computing the hash value and indicated in the data hash assertion shall match the dsci_key_source_uri bytes in the digitally signed content initialization SEI message.F00471 dsci_key_register_idx, when present, contains an index that specifies the certificate of the content provider, in the certificate register indicated by dsci key source uri, which can be used for verifying the signatures present in following digitally signed content verification SEI messages. The value of dsci_key_register_idx shall be in the range of 0 to 1023, inclusive.

[0048] The certificate indicated by the syntax elements dsci_key_retrieval_mode_idc, dsci_use_key_register_idx_flag, dsci_key_source_uri, and, if dsci_use_key_register_idx_flag is equal to 1, dsci key register idx shall specify a digital signature method, with associated parameters (if applicable), and the public key of the content provider. When dsci_key_retrieval_mode_idc is equal to 1, the format in which this information is provided is outside the scope of this specification. It is suggested that a digital signature algorithm conforming to the “Digital Signature Standard” NIST FIPS 186-5 is used.

[0049] dsci_content_uuid_present_flag equal to 1 specifies that the syntax element dsci_content_uuid is present, dsci content uuid present flag equal to 0 specifies that the syntax element dsci content uuid is not present. When dsci_key_retrieval_mode_idc is equal to 0 or IndependentNonBaseSubstreams is equal to 1, dsci_content_uuid_present_flag shall be equal to 1.

[0050] dsci_content_uuid, when present, indicates an identifier for the video content and shall have a value specified as a Universally Unique Identifier (UUID).

[0051] When a digitally signed content initialization SEI message is present in an AU, the calculation of NumVerificationSubstream message digests is initialized for the specified dsci_hash_method_type. Each non-VCL NAL unit with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL unit following the digitally signed content initialization SEI message is associated to one of the NumVerificationSubstream message digests; the verification substream id is either indicated by the digitally signed content selection SEI message or, if no digitally signed content selection SEI message is present for a PU, inferred to be equal to 0. The message used for calculating the k-th message digest, with k being in the range from 0 to dsci_num_verification_substreams_minusl, inclusive, is obtained by concatenating all non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units associated with the k-th verification substream. The calculation of the message digests is conducted based on blocks, where the block size is specified in Table XXX depending on the value of dsci_hash_method_type. For each non-VCL NAL unit with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL unit, the associated message digest is updated for the specified dsci_hash_method_type. Note that, since the message digests are calculated for the concatenation of all non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units for a verification substream, some of the processing blocks typically span over two or more successive NAL units.8.39 Digitally signed content selection SEI message8.39.1 Digitally signed content selection SEI message syntax8.39.2 Digitally signed content selection SEI message semantics

[0052] Use of this SEI message requires the definition of the following:- A list of non-VCL NAL unit type identifiers nonVclDigitallySignedNalUnitsList.

[0053] The digitally signed content selection SEI message provides a mechanism for associating coded pictures with one of the verification substreams indicated in a digitally signed content initialization SEI message identified by dsci id equal to dscs id.

[0054] When an AU contains both a digitally signed content initialization SEI message identified by dsci_id equal to dscs_id and a digitally signed content selection SEI message identified by dsci_id equal to dscs_id, the digitally signed content initialization SEI message identified by dsci id equal to dscs id shall precede the digitally signed content selection SEI message identified by dsci_id equal to dscs_id in decoding order.

[0055] When a CVS does not contain a digitally signed content initialization SEI message, CLVSs of the CVS shall not contain a digitally signed content selection SEI message.

[0056] When a digitally signed content selection SEI message is present in any PU of a CLVS, it shall precede all non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigiiallySignedNalUnitsList and VCL NAL units of the PU.

[0057] dscs_id contains an identifying number that may be used to identify a mechanism for verifying that the coded video has been produced by a content provider.

[0058] dscs_verific tion_substream_id indicates the verification substream to which the non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units of the current coded picture are assigned to. When a digitally signed content initialization SEI message was present in the current coded video sequence, but no corresponding digitally signed content selection SEI message identified by dsci id equal to dscs id is present for a coded picture, the value of dscs verification substream id and the value of dscs_id are inferred to be equal to 0. The value of dscs_verification_substream_id shall be in the range from 0 to dsci_num_verification_substreams_minusl, inclusive.

[0059] The message digest for the verification substream with id equal to dscs_verification_substream_id is updated with the non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units of the current coded picture according to the dsci_hash_method_type specified in the corresponding digitally signed content initialization SEI message identified by dsci_id equal to dscs_id.8.40 Digitally signed content verification SEI message8.40.1 Digitally signed content verification SEI message syntax8.40.2 Digitally signed content verification SEI message semantics

[0060] Use of this SEI message requires the definition of the following:- A list of non-VCL NAL unit type identifiers nonVclDigitallySignedNalUnitsList.

[0061] The digitally signed content verification SEI message provides a mechanism for verifying the digital signature of a substream indicated in a digitally signed content initialization SEI message indicated by dsci_id equal to dscv_id .

[0062] When a CVS does not contain a digitally signed content initialization SEI message identified by dsci_id equal to dscv_id, CLVSs of the CVS shall not contain digitally signed content verification SEI message identified by dsci id equal to dscv_id.

[0063] When an AU contains both a digitally signed content initialization SEI message identified by dsci_id equal to dscv_id and a digitally signed content verification SEI message identified by dsci id equal to dscv_id, the digitally signed content initialization SEI message shall precede the digitally signed content verification SEI message. When a PU contains both a digitally signed content selection SEI message identified by dsci_id equal to dscv_id and a digitally signed content verification SEI message identified by dsci_id equal to dscv_id, the digitally signed content selection SEI message shall precede the digitally signed content verification SEI message.

[0064] When a digitally signed content verification SEI message identified by dsci id equal to dscv_id is present in a PU of a CVS, no non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList or VCL NAL unit shall be assigned to the substream that is indicated by dscv_verification_substream_id, unless one or more of the following conditions are true:- The bitstream ends.- A new CVS begins.- A new digitally signed content initialization SET message is received.

[0065] dscv_id contains an identifying number that may be used to identify a mechanism for verifying that the coded video has been produced by a content provider.

[0066] dscv_verification_substream_id indicates the verification substream to which the SEI message applies.

[0067] It is constrained that the value of dscv_verification_substream_id of the first digitally signed content verification SEI message having a particular dscv_id value currDscvId that follows the last digitally signed content initialization SEI message having the dsci id value equal to currDscvId, in decoding order, shall be equal to 0.

[0068] Note 1 - When a new digitally signed content initialization SEI message with a particular identifier is present, new value space for substream identifiers in digitally signed content selection SEI messages (i.e., dscs_verification_substream_id) and digitally signed content verification SEI (i.e., dscv_verification_substream_id ) with the same identifier is used.

[0069] dscv_signature_length_in_octets_minusl plus 1 specifies the length of the syntax element dscv_signature in octets (one octet consists of 8 bits).

[0070] dscv_signature contains the digital signature for the verification substream indicated by dscv_verification_substream_id.

[0071] The variable sld is set equal to dscv_verification_substream_id.

[0072] The variable numRefs is set equal to DscNumRefSubstreams[ sld ].

[0073] The verification of the bitstream signature consists of the following ordered steps:The calculation of the message digest referred to as Cui rDigest is finalized as follows:- The concatenation of the non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units for the verification substream with id equal to dscv_verification_substream_id is padded. Note that it is sufficient to pad the last NAL unit of the verification substream.- The calculation of the message digest CurrDigest is finalized. The length (in bits) of the message digest is given in Table XXX.The reference message digest RefDigest[ relldx ] for refldx in the range of 0 .. numRefs, inclusive, is determined as follows:- If numRefs is greater than 0, the following applies:i. The reference message digest RefDigest[ refldx ] for each value of refldx in the range of 1 .. numRefs, inclusive, is set to the value of CurrDigest in the previous digitally signed content verification SEI message in decoding order with dscv_verification_substream_id equal to DscRefSubstreamId[ sld ][ refldx - 1 ]. It is a requirement of bitstream conformance that the digitally signed content verification SEI message associated with verification substream id equal to DscRefSubstreamldf sld ][ refldx- 1 ] shall be present before the digitally signed content verification SEI message with verification substream id equal to sld.ii. If the current digitally signed content verification SEI message with dscv_verification_substream_id equal to DscRefSubstreamId[ sld ]

[0000] is the first digitally signed content verification SEI in the coded video sequence and the preceding coded video sequence did not contain any digitally signed content initialization SEI message with dscv_verification substream id equal to DscRefSubstreamId[ sld ]

[0000] (this includes the case that the current coded video sequence is the first coded video sequence in the bitstream), RefDigest

[0000] is set equal to a bitstring that consists of DigestSize bits equal to 1, where DigestSize is the size of the message digest as specified in Table XXX.Otherwise, the reference message digest RefDigest

[0000] is the last calculated message digest for the verification substream with id equal to DscRefSubstreamldf sld ]

[0000] .- Otherwise, if the current digitally signed content verification SEI message is the first digitally signed content verification SEI with verification id equal to sld in the coded video sequence and the preceding coded video sequence did not contain any digitally signed content initialization SEI message (this includes the case that the current coded video sequence is the first coded video sequence in the bitstream), the RefDigest is set equal to a bitstring that consists of DigestSize bits equal to 1, where DigestSize is the size of the message digest as specified in Table XXX.- Otherwise, the reference message digest RefDigest is the last calculated message digest for the verification substream with id equal to sld.3. The identification string IdString is constructed by concatenating the binary representations of the reference message digest RefDigest[ refldx ], for refldx in 0 .. numRefs, inclusive, the current message digest, and the dsci_hash_method_type and, when present, the dsci_content_uuid, as illustrated in Figure XXX.Figure XXX - Construction of identification string IdString The number of bits for RefDigest[ refldx ] is determined by the value of dsci_hash_method_type which was valid when calculating the value of RefDigest[ refldx ], the number of bits for CurrDigest is determined by the current value of dsci_hash_method_type, and the value of dsci_hash_method_type is represented with 8 bits and, when present, the value of dsci_content_uuid is represented with 128 bits.4. The identification string IdString represents the message used for verifying the signature. The signature verification algorithm and the public key used for verifying the signature are indicated by the syntax elements dsci_use_key_register_idx_flag, dsci_key_source_uri, and, if dsci_use_key_register_idx_flag is equal to 1, dsci_key_register_idx.

[0074] NOTE 1 - Since the bitstring used for signature verification includes the RefDigest, it cannot only be verified that the non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units used for calculating the current message digest are correct, but it can additionally be verified that neither additional non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units were added to the bitstream nor non-VCL NAL units with a NAL unit type identifier among the values in nonVclDigitallySignedNalUnitsList and VCL NAL units were removed from the bitstream.

[0075] NOTE 2 - When a decoder tunes into a bitstream, the IdString constructed for the first digitally signed content verification SEI message cannot be verified, because the value of RefDigest cannot be calculated correctly. But starting from the second digitally signed content verification SEI message, the signatures can be verified. - It is a requirement of bitstream conformance that when verification of a verification substream substreamA with dscv_verification_substream_id value greater than 0 uses reference message digest from a verification substream substreamB, both of the following shall be true:- NAL units of PUs that are associated with substreamB shall not belong to a layer that is higher than the highest layer of the NAL units of PUs that are associated with substreamA.- When the highest layer of NAL units in substreamA and substreamB is equal, NAL units PUs that are associated with substreamB shall not belong to temporal sub layer that is higher than tire highest temporal sub layer of the NAL units of PUs that are associated with substreamA.

[0076] After verification, the message digest for the verification substream with id equal to dscv_verification_substream_id is reinitialized for the specified dsci_hash_method_type.4. Technical problems addressed by disclosed embodiments

[0077] An example design of the DSC SEI messages has the following problems:

[0078] First, relevant NAL units are associated to a verification substream, either explicitly by signalling the verification substream ID in a DSCS SEI message present in a PU, or implicitly by inferring the verification SLibstream ID equal to 0. Therefore, for typical bitstream with multiple layers and / or multiple temporal sublayers where each operation point corresponds to one verification substream, for each PU for which the VCL NAL units have either the layer identifier greater than the lowest value or the temporal sublayer identifier greater than 0, a DSCS SEI message needs to be included in the bitstream. Further, in this case, the number of verification substreams can also be inferred.

[0079] Second, the supported value range for the syntax elements for the verification substream ID in the DSCS and DSCV SEI messages may not be sufficient.

[0080] Third, the specified value range for the syntax element for the verification substream ID in the DSCS SEI message may not be sufficient.

[0081] Fourth, the default value range based on the length of the syntax element for the verification substream ID in the DSCV SEI message may be more than sufficient.5. A listing of solutions and embodiments

[0082] To address at least some of the above-described problems, methods as summarized below are disclosed. The aspects should be considered as examples to explain the general concepts and should not be interpreted in a narrow way. Furthermore, these examples can be applied individually or combined in any manner.1) In one example, one or more of the following variables are specified for use of the DSC SEI messages:a. A list of non-VCL NAL unit types NonVclDigitallySignedNalUnitsList.b. For a VCL NAL unit, a layer identifier, denoted herein by Layerld.c. For a VCL NAL unit, a temporal sublayer identifier, denoted herein by SubLrld.d. A variable indicating the maximum number of layers in the CVS, denoted herein by MaxNumLayers.e. A variable indicating the maximum number of temporal sublayers in the CVS, denoted herein by MaxNumSubLrs.2) In one example, one or more of the following aspects are specified for interpretation of the DSC SET messages in a VVC bitstream:a. A list NonVclDigitallySignedNalUnitsList is set to consist of the NAL units types with nal_unit_type values 14, 15, 16, 17, 18, and 19.b. For a VCL NAL unit, the variable Layerld is set equal to nuh layer id.c. For a VCL NAL unit, the variable SubLrld is set equal to Temporalld.d. The variable MaxNumLayers is set equal to vps max layers minusl + 1.e. The variable MaxNumSubLrs is set equal to vps_max_sublayers_minusl + 1.) In one example, one or more of the following aspects are specified:a. A verification period for a particular dsci id value dsddV l is defined as the sequence of AUs that is in a CVS and consists of, in decoding order, of an AU containing a DSCI SEI message with dsci_id equal to dsddVal, followed by zero or more AUs that do not contain a DSCI SET message with dsci id equal to dsddVal, including all subsequent AUs up to but not including any subsequence AU that does contain a DSCI SEI message with dsci_id equal to dsddVal. b. A verification NAL unit is defined as a NAL unit that is either a non-VCL NAL unit with NAL unit type among the values in NonVclDigitallySignedNalUnitsList or a VCL NAL unit. c. A verification substream for a particular dsci id value dsddVal is defined as all the verification NAL units associated with dscs_id equal to dsddVal and a particular verification substream ID value in a verification period for the particular dsci_id value.d. Within a verification period for a particular dsci id value dsddVal, the DSCI SEI message with dsci_id equal to dsddVal and a DSCS SEI message with dscs_id equal to dsddVal are said to be associated with each other, and the DSCI SET message with dsci_id equal to dsddVal and a DSCV SEI message with dscv_id equal to dsddVal are said to be associated with each other. ) In one example, the verification substream ID for the verification NAL units in a PU may be inferred to be a different value than 0.) In one example, the verification substream ID for the verification NAL units in a PU may be inferred to according to a maximum number of temporal sublayers (e.g., denoted by MaxNumSubLrs), a layer identifier (e.g., denoted by Layerld), and a temporal sublayer identifier (e.g., denoted by SubLrld).a. Tn one example, the verification substream ID for the verification NAL units in a PU may be inferred to be equal to MaxNumSubLrs * Layerld + SubLrld.) In one example, an indication is included in the DSCI SEI message syntax to indicate how to infer the verification substream ID for the verification NAL units in a PU.a. In one example, the indication may be a flag, e.g., named dsci_vss_implicit_association_mode_flag.i. In one example, at least one of the following aspects is specified:1. dsci_vss_implicit_association_mode_flag equal to 1 specifies that the verification substream ID for verification NAL units in a PU not containing a DSCS SEI message is inferred according to the value of MaxNumSubLrs and the values of Layerld and SubLrld of the VCL NAL units in the PU.2. dsci_vss_implicit_association_mode_flag equal to 0 specifies that the verification substream ID for verification NAL units in a PU not containing a DSCS SEI message is inferred to be equal to 0.ii. Tn one example, the dsci_vss_implicit_association_mode_flag is optionally included in the DSCI SEI message syntax.1. In one example, the inclusion of dsci_vss_implicit_association_mode_flag in the DSCI SET message syntax is conditioned when both the maximum number of layers (e.g., denoted by MaxNumLayers) and the maximum number of temporal sublayers (e.g., denoted by MaxNumSubLrs) are greater than 1. a. In one example, when not present, the value of dsci_vss_implicit_association_mode_flag is inferred to be equal to 0. iii. In one example, it is specified that, when a DSCI SEI message with dsci id equal to a particular value dsddVal is present in a CVS, but there is no DSCS SEI message with dscs_id equal to dsddVal in the current verification period, the value of the syntax elements for the verification substream ID in the DSCS SEI message, e.g., named dscs_vss_id, is inferred as follows:1. If dsci_vss_implicit_association_mode_flag is equal to 1, dscs_vss_id is inferred to be equal to MaxNumSubLrs * Layerld + SubLrld, where Layerld and SubLrld are the Layerld and SubLrld values, respectively, of the VCL NAL units in the current PU.2. Otherwise (dsci_vss_implicit_association_mode_flag is equal to 0), dscs_vss_id is inferred to be equal to 0.b. In one example, the indication may comprise a plurality of syntax elements, which indicate at least the following mode of implicit association of verification NAL units in a PU without a DSCV SEI message:i. The verification substream ID for the verification NAL units in the PU is inferred to be equal to a first value when the layer identifier of the VCL NAL units in the PU is among a first set of layer identifier values and the temporal sublayer identifier of the VCL NAL units is among a first set of temporal sublayer identifier values. The verification substream ID for the verification NAL units in the PU is inferred to be equal to a second value when the layer identifier of the VCL NAL units in the PU is among a second set of layer identifier values and the temporal sublayer identifier of the VCL NAL units is among a second set of temporal sublayer identifier values. The verification substream IDS for the verification NAL units in the PU may be inferred to equal to a third value, fourth value, and the like when the layer identifier of the VCL NAL units in the PU isamong a third, fourth (and the like) set of layer identifier values and the temporal sublayer identifier of the VCL NAL units is among a third, fourth (and the like) set of temporal sublayer identifier values.7) In one example, it is specified that the value of the syntax element for the verification substream ID in the DSCS SEI message, e.g., named dscs vss id, in a DSCS SEI message present in a verification period shall be in the range of 0 to the number of verification substreams minus 1 (e.g., denoted by dsci_num_vsss_minusl ), inclusive.a. In one example, the value range of dscs vss id is inferred to be 0 to 255, inclusive, which is implied by the u(8)-coding of the syntax element.b. In one example, dscs_vss_id is coded as ue(v), and in the semantics of the DSCS SEI message it is specified that tire value of dscs_vss_id shall be in the range of 0 to N, inclusive, where N is a positive integer, e.g., 1023 or 2047, and in the VVC interface text it is specified that the value of dscs_vss_id shall be in the range of 0 to ( vps_max_sublayers_minusl + 1 ) * 55 + 7, inclusive.8) In one example, it is specified that the value of the syntax element for the verification substream ID in the DSCV SEI message, e.g., named dscv_vss_id, shall be in the range of 0 to the number of verification substreams minus 1 (e.g., denoted by dsci_num_vsss_minusl), inclusive.a. In one example, dscv_vss_id is coded as ue(v), and in the semantics of the DSCV SET message it is specified that the value of dscv_vss_id shall be in the range of 0 to N, inclusive, where N is a positive integer, e.g., 1023 or 2047, and in the VVC interface text it is specified that the value of dscv_vss_id shall be in the range of 0 to ( vps_max_sublayers_minusl + 1 ) * 55 + 7, inclusive.9) In one example, the syntax element, e.g., named dsci_num_vsss_minusl, in the DSCI SEI message indicating the number of verification substreams may be optionally signalled.a. In one example, a new flag is added to the DSCI SEI message syntax, indicating the presence of dsci_num_vsss_minusl .i. When not present, the value of dsci num vsss minus 1 is inferred to be equal to the maximum number of layers (e.g., denoted by MaxNumLayers) multiplied by the maximum number of temporal sublayers (e.g., denoted by MaxNumSubLrs).ii. Alternatively, in one example, when not present, the value of dsci_num_vsss_minusl is inferred to be equal to the maximum number of layers (e.g., denoted by MaxNumLayers) multiplied by the maximum number of temporal sublayers (e.g., denoted by MaxNumSubLrs) minus 1.6. EmbodimentsF00831 Below are some example embodiments for tire aspects summarized in section 5. Most relevant parts that have been added or modified are shown in double braces (i.c., {{a}} indicates that ’a’ is added), and some ofthe deleted parts are shown in triple brackets (i.e., [[[a]]] indicates that ‘a’ is deleted). There may be some other changes that are editorial in nature and thus not highlighted.6.1 Embodiment 18.38 Digitally signed content SEI messages8.38.1 GeneralThe digitally signed content initialization (DSCI) SEI message, digitally signed content selection (DSCS) SEI message, and digitally signed content verification (DSCV) SEI message provide a mechanism for verifying that the coded video has been produced by a content provider that identifies itself via the digital certificate that is referenced in the DSCI SEI message. These three SEI messages are collectively referred to as the digitally signed content (DSC) SEI messages.{ {Use of the DSC SEI messages requires the definition of the following:- A list of non-VCL NAL unit types NonVclDigitallySignedNalUnitsList.- For a VCL NAL unit, a layer identifier, denoted herein by Layerld.- For a VCL NAL unit, a temporal sublayer identifier, denoted herein by SubLrld.- A variable indicating the maximum number of temporal sublayers in the CVS, denoted herein by MaxNumSubLrs .A verification period for a particular dsci_id value dsddVal is defined as the sequence of AUs that is in a CVS and consists of, in decoding order, of an AU containing a DSCI SEI message with dsci_id equal to dsddVal, followed by zero or more AUs that do not contain a DSCI SEI message with dsci_id equal to dsddVal, including all subsequent AUs up to but not including any subsequence AU that does contain a DSCI SEI message with dsci_id equal to dsddVal.A verification NAL unit is defined as a NAL unit that is either a non-VCL NAL unit with NAL unit type among the values in NonVclDigitallySignedNalUnitsList or a VCL NAL unit.A verification substream for a particular dsci_id value dsddVal is defined as all the verification NAL units associated with dscs id equal to dsddVal and a particular dscs vss id value in a verification period for the particular dsci_id value.Within a verification period for a particular dsci_id value dsddVal, the DSCI SEI message with dsci_id equal to dsddVal and a DSCS SEI message with dscs_id equal to dsddVal are said to be associated with each other, and the DSCI SEI message with dsci_id equal to dsddVal and a DSCV SEI message with dscv_id equal to dsddVal are said to be associated with each other. } j8.38.2 Digitally signed content initialization SEI message8.38.2.1 Digitally signed content initialization SEI message syntax8.38.2.2 Digitally signed content initialization SEI message semanticsThe DSCI SEI message with a particular dsci_id value provides information about the secure hash algorithm used for calculating message digests, which are used together with the digital signatures present in the associated DSCV SEI messages to verify the trustworthiness of all verification substreams in the current verification period (i.e., the verification period containing the current DSCI SEI message. It further provides information about the digital signature algorithm used and the public key of the content provider. The DSCI SEI message may provide the public key either by providing an URI that identifies a trust record, as specified in ISO / IEC 21617-1, that contains the certificate or by providing an URI that directly identifies the certificate.dsci_id contains an identifying number that may be used to identify a mechanism for verifying that the coded video represented by the current verification period has been produced by the content provider identified by the DSCI SEI message.dsci_num_vsss_minusl plus 1 indicates the number of verification substreams for which message digests are calculated and signatures may be present in the associated DSCV SEI messages. The value of dsci_num_vsss_minusl shall be in the range of 0 to 255, inclusive.The variable NumVerificationSubstreams is derived as:NumVerificationSubstreams = dsci_num_vsss_minusl + 1.{ {dsci_vss_implicit_association_mode_flag equal to i specifies that the verification substream ID for verification NAL units in a PU not containing a DSCS SEI message is inferred according to the value of MaxNumSubLrs and the values of Layerld and SubLrld of the VCL NAL units in the PU. dsci_vss_implicit_association_mode_flag equal to 0 specifies that the verification substream ID for verification NAL units in a PU not containing a DSCS SEI message is inferred to be equal to 0. ] )dsci_key_retrieval_mode_idc equal to 0 indicates that the URI contained in dsci_key_source_uri specifies a trust record, as specified in ISO / TEC 21617-1. dsci_key_retrieval_mode_idc equal to 1 indicates that the URI contained in dsci key source Liri and, when present, dsci key register idx specify a certificate. In this version of this Specification dsci_key_retrieval_mode_idc shall be in the range of 0 to 1, inclusive. Decoders shall also allow other values of dsci_key_retrieval_mode_idc, but, when dsci_key_retrieval_mode_idc is greater than 1, shall ignore the DSCI SEI message as well as the associated DSCS and DSCV SEI messages.8.38.3 Digitally signed content selection SEI message8.38.3.1 Digitally signed content selection SEI message syntax8.38.3.2 Digitally signed content selection SEI message semanticsThe digitally signed content selection SEI message provides a mechanism for associating verification NAL units in a PU with one of the verification substreams indicated in a DSCI SEI message with dsci_id equal to dscs_id.dscs_id contains an identifying number that may be used to identify a mechanism for verifying that the coded video represented by the current verification period (i.e., the verification period for dsci_id equal to dscs_id containing the current DSCS SEI message) has been produced by the content provider indicated by the associated DSCI SEI message.dscs_vss_id specifies the verification substream ID of the verification substream to which the verification NAL units in the current PU are assigned to. { {When a DSCI SET message with dsci_id equal to a particular value dsddVal is present in a CVS, but there is no DSCS SEI message with dscs id equal to dsddVal in the current verification period,) } the value of dscs_id is inferred to be equal to 0, and { {the value of dscs_vss_id is inferred as follows:- If dsci_vss_implicit_association_mode_flag is equal to 1, dscs_vss_id is inferred to be equal to MaxNumSubLrs * Layerld + SubLrld, where Layerld and SubLrld are the Layerld and SubLrld values, respectively, of the VCL NAL units in the current PU.- Otherwise (dsci_vss_implicit_association_mode_flag is equal to 0), dscs_vss_id is inferred to be equal to 0. } } The value of dscs vss id { {in a DSCS SEI message present in a verification period) ] shall be in the range of 0 to dsci_num_vsss_minusl, inclusive.As specified in clause 8.38.2.2, the message digest for the verification substream with verification substream ID equal to dscs vss id is updated with the verification NAL units in the current PU according to the dsci_hash_method_type specified in the associated DSCI SEI message.8.38.4 Digitally signed content verification SEI message8.38.4.1 Digitally signed content verification SEI message syntax8.38.4.2 Digitally signed content verification SEI message semanticsThe DSCV SEI message provides a mechanism for verifying the digital signature of a verification substream indicated in a DSCI SEI message identified by dsci_id equal to dscv_id.dscv_id contains an identifying number that may be used to identify a mechanism for verifying that the coded video represented by the current verification period has been produced by the content provider indicated by the associated DSCI SEI message.dscv_vss_id specifies the verification substream ID of the verification substream to which the SEI message applies. { {The value of dscv_vss_id shall be in the range of 0 to dsci_num_vsss_minusl, inclusive.) }7. References[1] Rec. ITU-T H.26 2, “High efficiency video coding”.{2] Rec. ITU-T H.26 3, “Versatile Video Coding”.[3] Rec. ITU-T Rec. 002-7, “Versatile Supplemental Enhancement Information Messages for Coded Video Bit[4] J. Boyce, J. Chen, S. Deshpande, M. M. Hannuksela, S. McCarthy, G. J. Sullivan, H. Tan, Y.-K. Wang (editors), “Additional SEI messages for VSEI version 4 (Draft 5),” JVET output document JVET-AK2006- v2, publicly available online herein: https: / / www.jvet- experts.org / doc_end_user / documents / 37_Geneva / wgl 1 / JVET- AK2006-v2.zip.

[0084] FIG. 1 is a block diagram showing an example video processing system 4000 in which various embodiments disclosed herein may be implemented. Various implementations may include some or all of the components of the system 4000. The system 4000 may include input 4002 for receiving video content. The video content may be received in a raw or uncompressed format, e.g., 8- or 10-bit multi-component pixel values, or may be in a compressed or encoded format. The input 4002 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON), etc. and wireless interfaces such as Wi-Fi or cellular interfaces.

[0085] The system 4000 may include a coding component 4004 that may implement the various coding or encoding methods described in the present disclosure. The coding component 4004 may reduce the average bitrate of video from the input 4002 to the output of the coding component 4004 to produce a coded representation of the video. The coding techniques are therefore sometimes called video compression or video transcoding techniques. The output of the coding component 4004 may be either stored, or transmitted via a communication connected, as represented by the component 4006. The stored or communicated bitstream (or coded) representation of the video received at the input 4002 may be used by a component 4008 for generating pixel values or displayable video that is sent to a display interface 4010. The process of generating user- viewable video from the bitstream representation is sometimes called video decompression. Furthermore, while certain video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by a decoder.

[0086] Examples of a peripheral bus interface or a display interface may include universal serial bus (LTSB) or high definition multimedia interface (HDMI) or DisplayPort, and so on. Examples of storage interfaces include serial advanced technology attachment (SATA), peripheral component interconnect (PCI), integrated drive electronics (IDE) interface, and the like. The embodiments described in the present disclosure may be embodied in various electronic devices such as mobile phones, laptops, smartphones or other devices that are capable of performing digital data processing and / or video display.

[0087] FIG. 2 is a block diagram of an example video processing apparatus 4100. The apparatus 4100 may be used to implement one or more of the methods described herein. The apparatus 4100 may be embodied in a smartphone, tablet, computer, Internet of Things (loT) receiver, and so on. The apparatus 4100 may include one or more processors 4102, one or more memories 4104 and video processing circuitry 4106. The processor(s) 4102 may be configured to implement one or more methods described in the present disclosure. The memory (memories) 4104 may be used for storing data and code used for implementing the methods and embodimentsdescribed herein. The video processing circuitry 4106 may be used to implement, in hardware circuitry, some embodiments described in the present disclosure. In some embodiments, the video processing circuitry 4106 may be at least partly included in the processor 4102, e.g., a graphics co-processor.

[0088] FIG. 3 is a flowchart for an example method 4200 of video processing. The method 4200 determines a list of non-video coding layer (non-VCL) network abstraction layer (NAL) unit types (NonVclDigitallySignedNalUnitsList) signalled in a Digitally Signed Content (DSC) supplemental enhancement information (SEI) message at step 4202. A conversion is performed between a visual media data and a bitstream based on the DSC SEI message at step 4204. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

[0089] It should be noted that the method 4200 can be implemented in an apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, such as video encoder 4400, video decoder 4500, and / or encoder 4600. In such a case, the instructions upon execution by the processor, cause the processor to perform the method 4200. Further, the method 4200 can be performed by a non-transitory' computer readable medium comprising a computer program product for use by a video coding device. The computer program product comprises computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method 4200.

[0090] FIG. 4 is a block diagram that illustrates an example video coding system 4300 that may utilize the embodiments of this disclosure. The video coding system 4300 may include a source device 4310 and a destination device 4320. Source device 4310 generates encoded video data which may be referred to as a video encoding device. Destination device 4320 may decode the encoded video data generated by source device 4310 which may be referred to as a video decoding device.

[0091] Source device 4310 may include a video source 4312, a video encoder 4314, and an input / output (I / O) interface 4316. Video source 4312 may include a source such as a video capture device, an interface to receive video data from a video content provider, and / or a computer graphics system for generating video data, or a combination of such sources. The video data may comprise one or more pictures. Video encoder 4314 encodes the video data from video source 4312 to generate a bitstream. The bitstream may include a sequence of bits that form a coded representation of the video data. The bitstream may include coded pictures and associated data. The coded picture is a coded representation of a picture. The associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. I / O interface 4316 may include a modulator / demodulator (modem) and / or a transmitter. The encoded video data may be transmitted directly to destination device 4320 via I / O interface 4316 through network 4330. The encoded video data may also be stored onto a storage medium / server 4340 for access by destination device 4320.

[0092] Destination device 4320 may include an I / O interface 4326, a video decoder 4324, and a display device 4322. I / O interface 4326 may include a receiver and / or a modem. I / O interface 4326 may acquire encoded video data from the source device 4310 or the storage medium / server 4340. Video decoder 4324 may decode the encoded video data. Display device 4322 may display the decoded video data to a user. Display device 4322 may be integrated with the destination device 4320, or may be external to destination device 4320, which can be configured to interface with an external display device.

[0093] Video encoder 4314 and video decoder 4324 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, Versatile Video Coding (VVC) standard and other current and / or further standards.

[0094] FIG. 5 is a block diagram illustrating an example of video encoder 4400, which may be video encoder 4314 in the system 4300 illustrated in FIG. 4. Video encoder 4400 may be configured to perform any or all of the embodiments of this disclosure. The video encoder 4400 includes a plurality of functional components. The embodiments described in this disclosure may be shared among the various components of video encoder 4400. In some examples, a processor may be configured to perform any or all of the embodiments described in this disclosure.

[0095] The functional components of video encoder 4400 may include a partition unit 4401 ; a prediction unit 4402, which may include a mode select unit 4403, a motion estimation unit 4404, a motion compensation unit 4405, and an intra prediction unit 4406; a residual generation unit 4407; a transform processing unit 4408; a quantization unit 4409; an inverse quantization unit 4410; an inverse transform unit 4411; a reconstruction unit 4412; a buffer 4413; and an entropy encoding unit 4414.

[0096] In other examples, video encoder 4400 may include more, fewer, or different functional components. In an example, prediction unit 4402 may include an intra block copy (IBC) unit. The IBC unit may perform prediction in an IBC mode in which at least one reference picture is a picture where the cunent video block is located.

[0097] Furthermore, some components, such as motion estimation unit 4404 and motion compensation unit 4405 may be highly integrated, but are represented in the example of video encoder 4400 separately for purposes of explanation.

[0098] Partition unit 4401 may partition a picture into one or more video blocks. Video encoder 4400 and video decoder 4500 may support various video block sizes.

[0099] Mode select unit 4403 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra or inter coded block to a residual generation unit 4407 to generate residual block data and to a reconstruction unit 4412 to reconstruct the encoded block for use as a reference picture. Tn some examples, mode select unit 4403 may select a combination of intra and inter prediction (CIIP) mode in which the prediction is based on an inter prediction signal and an intra prediction signal. Mode select unit 4403 may alsoselect a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter prediction.roiooi To perform inter prediction on a current video block, motion estimation unit 4404 may generate motion information for the current video block by comparing one or more reference frames from buffer 4413 to the current video block. Motion compensation unit 4405 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 4413 other than the picture associated with the current video block.

[0101] Motion estimation unit 4404 and motion compensation unit 4405 may perform different operations for a current video block, for example, depending on whether the current video block is in an I slice, a P slice, or a B slice.

[0102] In some examples, motion estimation unit 4404 may perform uni-directional prediction for the current video block, and motion estimation unit 4404 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. Motion estimation unit 4404 may then generate a reference index that indicates the reference picture in list 0 or list 1 that contains the reference video block and a motion vector that indicates a spatial displacement between the current video block and the reference video block. Motion estimation unit 4404 may output the reference index, a prediction direction indicator, and the motion vector as the motion information of the current video block. Motion compensation unit 4405 may generate the predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.

[0103] In other examples, motion estimation unit 4404 may perform bi-directional prediction for the current video block, motion estimation unit 4404 may search the reference pictures in list 0 for a reference video block for the current video block and may also search the reference pictures in list 1 for another reference video block for the current video block. Motion estimation unit 4404 may then generate reference indexes that indicate the reference pictures in list 0 and list 1 containing the reference video blocks and motion vectors that indicate spatial displacements between the reference video blocks and the current video block. Motion estimation unit 4404 may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. Motion compensation unit 4405 may generate the predicted video block of the current video block based on the reference video blocks indicated by the motion information of the current video block.

[0104] In some examples, motion estimation unit 4404 may output a full set of motion information for decoding processing of a decoder. In some examples, motion estimation unit 4404 may not output a full set of motion information for the current video. Rather, motion estimation unit 4404 may signal the motion information of the current video block with reference to the motion information of another video block. For example, motion estimation unit 4404 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block.

[0105] In one example, motion estimation unit 4404 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 4500 that the current video block has the same motion information as another video block.

[0106] Tn another example, motion estimation unit 4404 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD). The motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 4500 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0107] As discussed above, video encoder 4400 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder 4400 include advanced motion vector prediction (AMVP) and merge mode signaling.

[0108] Intra prediction unit 4406 may perform intra prediction on the current video block. When intra prediction unit 4406 performs intra prediction on the current video block, intra prediction unit 4406 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture. The prediction data for the current video block may include a predicted video block and various syntax elements.

[0109] Residual generation unit 4407 may generate residual data for the current video block by subtracting the predicted video block(s) of the current video block from the current video block. The residual data of the current video block may include residual video blocks that correspond to different sample components of the samples in the current video block.

[0110] In other examples, there may be no residual data for the current video block for the current video block, for example in a skip mode, and residual generation unit 4407 may not perform the subtracting operation.

[0111] Transform processing unit 4408 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.

[0112] After transform processing unit 4408 generates a transform coefficient video block associated with the current video block, quantization unit 4409 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.

[0113] Inverse quantization unit 4410 and inverse transform unit 4411 may apply inverse quantization and inverse transforms to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block. Reconstruction unit 4412 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the prediction unit 4402 to produce a reconstructed video block associated with the current block for storage in the buffer 4413.

[0114] After reconstruction unit 4412 reconstructs the video block, the loop filtering operation may be performed to reduce video blocking artifacts in the video block.

[0115] Entropy encoding unit 4414 may receive data from other functional components of the video encoder 4400. When entropy encoding unit 4414 receives the data, entropy encoding unit 4414 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.

[0116] FIG. 6 is a block diagram illustrating an example of video decoder 4500 which may be video decoder 4324 in the system 4300 illustrated in FIG. 4. The video decoder 4500 may be configured to perform any or all of the embodiments of this disclosure. In the example shown, the video decoder 4500 includes a plurality of functional components. The embodiments described in this disclosure may be shared among the various components of the video decoder 4500. In some examples, a processor may be configured to perform any or all of the embodiments described in this disclosure.

[0117] In the example shown, video decoder 4500 includes an entropy decoding unit 4501, a motion compensation unit 4502, an intra prediction unit 4503, an inverse quantization unit 4504, an inverse transformation unit 4505, a reconstruction unit 4506, and a buffer 4507. Video decoder 4500 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 4400.

[0118] Entropy decoding unit 4501 may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data). Entropy decoding unit 4501 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 4502 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 4502 may, for example, determine such information by performing the AM VP and merge mode.

[0119] Motion compensation unit 4502 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.

[0120] Motion compensation unit 4502 may use interpolation filters as used by video encoder 4400 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 4502 may determine the interpolation filters used by video encoder 4400 according to received syntax information and use the interpolation filters to produce predictive blocks.

[0121] Motion compensation unit 4502 may use some of the syntax information to determine sizes of blocks used to encode frame(s) and / or slice(s) of the encoded video sequence, partition information that describes how each macroblock of a picture of the encoded video sequence is partitioned, modes indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter coded block, and other information to decode the encoded video sequence.

[0122] Intra prediction unit 4503 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit 4504 inverse quantizes, i.e., dequantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 4501. Inverse transform unit 4505 applies an inverse transform.

[0123] Reconstruction unit 4506 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 4502 or intra prediction unit 4503 to form decoded blocks. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts. The decoded video blocks are then stored in buffer 4507, which provides reference blocks for subsequent motion compensation / intra prediction and also produces decoded video for presentation on a display device.

[0124] FIG. 7 is a schematic diagram of an example encoder 4600. The encoder 4600 is suitable for implementing the techniques of VVC. The encoder 4600 includes three in-loop filters, namely a deblocking filter (DF) 4602, a sample adaptive offset (SAG) 4604, and an adaptive loop filter (ALF) 4606. Unlike the DF 4602, which uses predefined filters, the SAG 4604 and the ALF 4606 utiliz,e the original samples of the current picture to reduce the mean square errors between the original samples and the reconstructed samples by adding an offset and by applying a finite impulse response (FIR) filter, respectively, with coded side information signaling the offsets and filter coefficients. The ALF 4606 is located at the last processing stage of each picture and can be regarded as a tool trying to catch and fix artifacts created by the previous stages.

[0125] The encoder 4600 further includes an intra prediction component 4608 and a motion estimation / compensation (ME / MC) component 4610 configured to receive input video. The intra prediction component 4608 is configured to perform intra prediction, while the ME / MC component 4610 is configured to utilize reference pictures obtained from a reference picture buffer 4612 to perform inter prediction. Residual blocks from inter prediction or intra prediction are fed into a transform (T) component 4614 and a quantization (Q) component 4616 to generate quantized residual transform coefficients, which are fed into an entropy coding component 4618. The entropy coding component 4618 entropy codes the prediction results and the quantized transform coefficients and transmits the same toward a video decoder (not shown). Quantization components output from the quantization component 4616 may be fed into an inverse quantization (IQ) components 4620, an inverse transform component 4622, and a reconstruction (REC) component 4624. The REC component 4624 is able to output images to the DF 4602, the SAG 4604, and the ALF 4606 for filtering prior to those images being stored in the reference picture buffer 4612.

[0126] A listing of solutions preferred by some examples is provided next.

[0127] The following solutions show examples of embodiments discussed herein.

[0128] 1. A method for processing media data comprising: determining a list of non- video coding layer (non-VCL) network abstraction layer (NAL) unit types (NonVclDigitallySignedNalUnitsList) signalled in aDigitally Signed Content (DSC) supplemental enhancement information (SEI) message; and performing a conversion between a visual media data and a bitstream based on the DSC SEI message.F01291 2. The method of solution 1, wherein the DSC SEI message contains a layer identifier (Layerld) for a video coding layer (VCL) NAL unit, a temporal sublayer identifier (SubLrld) for a VCL NAL unit, a variable indicating a maximum number of layers (MaxNumLayers) in a coded video sequence (CVS), or a variable indicating a maximum number of temporal sublayers (MaxNumSubLrs) in the CVS.

[0130] 3. The method of any of solutions 1-2, wherein for the DSC SEI message: the list NonVclDigitallySignedNalUnitsList is set to comprise the NAL units types with nal_unit_type values 14, 15, 16, 17, 18, and 19, the variable Layerld is set equal to NAL unit header (nuh) layer identifier (nuh layer id) for a VCL NAL unit, the variable SubLrld is set equal to temporal identifier (Temporalld) for a VCL NAL unit, the variable MaxNumLayers is set equal to video parameter set (VPS) maximum layers minus one (vps_max_layers_minusl) + 1, or the variable MaxNumSubLrs is set equal to vps_max_sublayers_minusl + 1.

[0131] 4. The method of any of solutions 1-3, wherein a verification period for a particular DSC initialization (DSCI) identifier (dsci id) value dsddVal is defined as the sequence of access units (AUs) that is in a CVS and comprises, in decoding order, an AU containing a DSCI SEI message with dsci_id equal to dsddVal, followed by zero or more AUs that do not contain a DSCI SET message with dsci_id equal to dsddVal, including all subsequent AUs up to but not including any subsequence AU that does contain a DSCI SEI message with dsci_id equal to dsddVal, or wherein a verification NAL unit is defined as a NAL unit that is either a non-VCL NAL unit with NAL unit type among the values in NonVclDigitallySignedNalUnitsList or a VCL NAL unit, or wherein a verification substream for a particular dsci id value (dsddVal) is defined as all the verification NAL units associated with dscs id equal to dsddVal and a particular verification substream ID value in a verification period for the particular dsci_id value, or wherein within a verification period for a particular dsci_id value dsddVal, the DSCI SET message with dsci_id equal to dsddVal and a DSCS SET message with dscs_id equal to dsddVal are said to be associated with each other, and the DSCI SEI message with dsci id equal to dsddVal and a DSCV SEI message with dscv_id equal to dsddVal are said to be associated with each other.

[0132] 5. The method of any of solutions 1-4, wherein a verification substream identifier (ID) for the verification NAL units in a PU may be inferred to be a different value than 0.

[0133] 6. The method of any of solutions 1-5, wherein a verification substream ID for the verification NAL units in a PU may be inferred to according to a maximum number of temporal sublayers (MaxNumSubLrs), a layer identifier (Layerld), and a temporal sublayer identifier (SubLrld).

[0134] 7. The method of any of solutions 1-6, wherein the verification substream ID for the verification NAL units in a PU may be inferred to be equal to MaxNumSubLrs * Layerld + SubLrld.

[0135] 8. The method of any of solutions 1-7, wherein an indication is included in the DSCI SEI message syntax to indicate how to infer the verification substream ID for the verification NAL units in a PU.

[0136] 9. The method of any of solutions 1-8, wherein the indication is a flag named dsci_vss_implicit_association_mode_flag.

[0137] 10. The method of any of solutions 1-9, wherein dsci_vss_implicit_association_mode_flag equal to 1 specifies that the verification substream ID for verification NAL units in a PU not containing a DSCS SEI message is inferred according to the value of MaxNumSubLrs and the values of Layerld and SubLrld of the VCL NAL units in the PU, or wherein dsci_vss_implicit_association_mode_flag equal to 0 specifies that the verification substream ID for verification NAL units in a PU not containing a DSCS SEI message is inferred to be equal to 0.

[0138] 11. The method of any of solutions 1-10, wherein the dsci_vss_implicit_association_mode_flag is optionally included in the DSCI SEI message syntax, or wherein the inclusion of dsci_vss_implicit_association_mode_flag in the DSCI SEI message syntax is conditioned when both the maximum number of and the maximum number of temporal sublayers are greater than 1, or wherein when not present, the value of dsci_vss_implicit_association_mode_flag is inferred to be equal to 0.

[0139] 12. The method of any of solutions 1-11, wherein when a DSCI SEI message with dsci_id equal to a particular value dsddVal is present in a CVS, but there is no DSCS SEI message with dscs_id equal to dsddVal in the current verification period, the value of the syntax elements for the verification substream ID in the DSCS SEI message (dscs_vss_id) is inferred as follows: when dsci_vss_implicit_association_mode_flag is equal to 1, dscs_vss_id is inferred to be equal to MaxNumSubLrs * Layerld + SubLrld, where Layerld and SubLrld are the Layerld and SubLrld values, respectively, of the VCL NAL units in the current PU; and otherwise when dsci_vss_implicit_association_mode_flag is equal to 0, dscs_vss_id is inferred to be equal to 0.

[0140] 13. The method of any of solutions 1-12, wherein the indication may comprise a plurality of syntax elements, which indicate at least the following mode of implicit association of verification NAL units in a PU without a DSCV SET message: the verification substream ID for the verification NAL units in the PU is inferred to be equal to a first value when the layer identifier of the VCL NAL units in the PU is among a first set of layer identifier values and the temporal sublayer identifier of the VCL NAL units is among a first set of temporal sublayer identifier values, and the verification substream ID for the verification NAL units in the PU is inferred to be equal to a second value when the layer identifier of the VCL NAL units in the PU is among a second set of layer identifier values and the temporal sublayer identifier of the VCL NAL units is among a second set of temporal sublayer identifier values.

[0141] 14. The method of any of solutions 1-13, wherein the value of the syntax element for the verification substream ID (dscs_vss_id) in the DSCS SEI message in a DSCS SEI message present in a verification period shall be in the range of 0 to the number of verification substreams minus 1 (dsci_num_vsss_minusl), inclusive, or wherein the value range of dscs vss id is inferred to be 0 to 255, inclusive, which is implied by the u(8)-coding of the syntax element, or wherein dscs_vss_id is coded as ue(v), and in the semantics of the DSCS SEI messageit is specified that the value of dscs_vss_id shall be in the range of 0 to N, inclusive, where N is a positive integer, e.g., 1023 or 2047, and in the VVC interface text it is specified that the value of dscs vss id shall be in the range of 0 to ( vps_max_sublayers_minusl + 1 ) * 55 + 7, inclusive.

[0142] 15. The method of any of solutions 1-14, wherein the value of the syntax element for the verification substream ID in the DSCV SEI message (dscv_vss_id), shall be in the range of 0 to the number of verification substreams minus 1 (dsci_num_vsss_minusl), inclusive, or wherein dscv_vss_id is coded as ue(v), and in the semantics of the DSCV SEI message it is specified that the value of dscv_vss_id shall be in the range of 0 to N, inclusive, where N is a positive integer and in the VVC interface text it is specified that the value of dscv_vss_id shall be in the range of 0 to ( vps_max_sublayers_minus1 + 1 ) * 55 + 7, inclusive.

[0143] 16. The method of any of solutions 1-15, wherein a syntax element (dsci_num_vsss_minusl) in the DSC! SET message indicating the number of verification substreams is optionally signalled, or wherein a new flag is added to the DSCI SEI message syntax, indicating the presence of dsci_num_vsss_minusl, or wherein when not present, the value of dsci_num_vsss_minusl is inferred to be equal to the maximum number of layers (MaxNumLayers) multiplied by the maximum number of temporal sublayers (MaxNumSubLrs), or wherein when not present, the value of dsci_num_vsss_minusl is inferred to be equal to the maximum number of layers (MaxNumLayers) multiplied by the maximum number of temporal sublayers (MaxNumSubLrs) minus 1.

[0144] 17. The method of any of solutions 1-16, wherein the conversion includes encoding the visual media data into the bitstream.

[0145] 18. The method of any of solutions 1-16, wherein the conversion includes decoding the visual media data from the bitstream.

[0146] 19. An apparatus for processing video data comprising: a processor; and a non- transitory memory' with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of solutions 1-18.

[0147] 20. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of solutions 1-18.

[0148] 21. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining a list of non-video coding layer (non-VCL) network abstraction layer (NAL) unit types (NonVclDigitallySignedNalUnitsList) signalled in a Digitally Signed Content (DSC) supplemental enhancement information (SEI) message; and generating a bitstream based on the determining.

[0149] 22. A method for storing bitstream of a video comprising: determining a list of non-video coding layer (non-VCL) network abstraction layer (NAL) unit types (NonVclDigitallySignedNalUnitsList) signalled ina Digitally Signed Content (DSC) supplemental enhancement information (SEI) message; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium, roisoi 23. A method, apparatus, or system described in the present disclosure.

[0151] Tn the solutions described herein, an encoder may conform to the format rule by producing a coded representation according to the format rule. In the solutions described herein, a decoder may use the format rule to parse syntax elements in the coded representation with the knowledge of presence and absence of syntax elements according to the format rule to produce decoded video.

[0152] In the present disclosure, the term “video processing” may refer to video encoding, video decoding, video compression or video decompression. For example, video compression algorithms may be applied during conversion from pixel representation of a video to a corresponding bitstream representation or vice versa. The bitstream representation of a current video block may, for example, correspond to bits that are either co-located or spread in different places within the bitstream, as is defined by the syntax. For example, a macroblock may be encoded in terms of transformed and coded error residual values and also using bits in headers and other fields in the bitstream. Furthermore, during conversion, a decoder may parse a bitstream with the knowledge that some fields may be present, or absent, based on the determination, as is described in the above solutions. Similarly, an encoder may determine that certain syntax fields are or are not to be included and generate the coded representation accordingly by including or excluding the syntax fields from the coded representation.

[0153] The disclosed and other solutions, examples, embodiments, modules and the functional operations described in this disclosure can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this disclosure and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine -readable storage device, a machine -readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. Tile apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.

[0154] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0155] The processes and logic flows described in this disclosure can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., a field-programmable gate array (FPGA) or an applicationspecific integrated circuit (ASIC).

[0156] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory' devices, including by way of example semiconductor memory devices, e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and Hash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and compact disc read-only memory (CD ROM) and Digital versatile disc-read only memory' (DVD-ROM) disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0157] While the present disclosure contains many specifics, these should not be construed as limitations on the scope of any subject matter or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of the present disclosure. Certain features that are described in the present disclosure in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0158] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in the present disclosure should not be understood as requiring such separation in all embodiments.

[0159] Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in the present disclosure.

[0160] A first component is directly coupled to a second component when there are no intervening components, except for a line, a trace, or another medium between the first component and the second component. The first component is indirectly coupled to the second component when there are intervening components other than a line, a trace, or another medium between the first component and the second component. The term “coupled” and its variants include both directly coupled and indirectly coupled. The use of the term “about” means a range including ±10% of the subsequent number unless otherwise stated.

[0161] While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.

[0162] In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled may be directly connected or may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

CLAIMSWhat is claimed is:

1. A method for processing media data, comprising:determining a syntax element associated with a digitally signed content (DSC) supplemental enhancement information (SEI) message; andperforming a conversion between a visual media data and a bitstream based on the DSC SEI message.

2. The method of claim 1, wherein the syntax element is for a verification substream ID in a DSC selection (DSCS) SEI message (dscs_vss_id), wherein a value of the syntax element in a DSCS SEI message present in a verification period shall be in the range of 0 to a number of verification substreams minus 1 (dsci_num_vsss_minusl), inclusive.

3. The method of any of claims 1 -2, wherein a value range of dscs_vss_id is inferred to be 0 to 255 , inclusive, based on the syntax element being u(8)-coded.

4. The method of any of claims 1-3, wherein dscs_vss_id is coded as ue(v), and semantics of the DSCS SEI message specify that the value of dscs_vss_id shall be in a range of 0 to N, inclusive, where N is a positive integer, and wherein an interface text specifies that the value of dscs_vss_id shall be in a range of 0 to ( vps_max_sublayers_minusl + 1 ) * 55 + 7, inclusive.

5. Tile method of claim 4, wherein N = 1023 or N = 2047.

6. The method of claim 1 , wherein the syntax element is for a verification substream ID in a DSC verification (DSCV) SEI message (dscv_vss_id), wherein a value of the syntax element shall be in the range of 0 to a number of verification substreams minus 1 (dsci_num_vsss_minusl), inclusive.

7. The method of claim 6, wherein dscv_vss_id is coded as ue(v), and semantics of the DSCV SEI message specify that the value of dscv_vss_id shall be in a range of 0 to N, inclusive, where N is a positive integer, and wherein an interface text specifies that the value of dscv_vss_id shall be in a range of 0 to ( vps_max_sublayers_minusl + 1 ) * 55 + 7, inclusive.

8. The method of claim 1, wherein the syntax element indicates a number of verification substreams in a DSC initialization (DSCI) SEI message (dsci_num_vsss_minusl) and is optionally signalled.

9. The method of claim 8, wherein a new flag is added to the DSCI SEI message syntax, indicating that dsci_num_vsss_minusl is present.

10. Tile method of any of claims 8-9, wherein when not present, a value of dsci_num_vsss_minusl is inferred to be equal to a maximum number of layers (MaxNumLayers) multiplied by a maximum number of temporal sublayers (MaxNumSubLrs).

11. The method of any of claims 8-9, wherein when not present, a value of dsci num vsss minus 1 is inferred to be equal to a maximum number of layers (MaxNumLayers) multiplied by a maximum number of temporal sublayers (MaxNumSubLrs) minus 1.

12. The method of any of claims 1-11, wherein the conversion includes encoding the visual media data into the bitstream.

13. The method of any of claims 1-11, wherein the conversion includes decoding the visual media data from the bitstream.

14. An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of claims 1-13.

15. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of claims 1-13.

16. A non-transitory' computer -readable recording medium storing a bitstream of a video which is generated by a method performed by' a video processing apparatus, wherein the method comprises:determining a syntax element associated with a digitally signed content (DSC) supplemental enhancement information (SEI) message; andgenerating a bitstream based on the determining.

17. A method for storing bitstream of a video comprising:determining a syntax element associated with a digitally signed content (DSC) supplemental enhancement information (SEI) message; andgenerating a bitstream based on the determining; andstoring the bitstream in a non-transitory computer -readable recording medium.

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