WO2026010973A1 - Signalling of media content trustworthiness information - Google Patents

Abstract

A mechanism for processing video data is disclosed. The mechanism includes determining a digital signature in a content selection supplemental enhancement information (SEI) message applies to at least one single region of a picture. A conversion is performed between a visual media data and a bitstream based on the digital signature.

Description

Signalling of Media Content Trustworthiness Information

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority to and benefits of U.S. Provisional Patent Application No. 63/666,945, filed on July 2, 2024. All the aforementioned patent applications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

[0002] This patent document relates to generation, storage, and consumption of digital audio video media information in a file format.

BACKGROUND

[0003] Digital video accounts for the largest bandwidth used on the Internet and other digital communication networks. As the number of comiected 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 digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture; and performing a conversion between a visual media data and a bitstream based on the digital signature.

[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 digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture: 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 digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer- readable recording medium.

[0009] 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. [0010] These and other features will be more clearly understood from the following detailed description taken in conj unction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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.

[0012] FIG. 1 is a block diagram showing an example construction of identification string IdString.

[0013] FIG. 2 is a block diagram showing an example video processing system.

[0014] FIG. 3 is a block diagram of an example video processing apparatus.

[0015] FIG. 4 is a flowchart for an example method of video processing.

[0016] FIG. 5 is a block diagram that illustrates an example video coding system.

[0017] FIG. 6 is a block diagram that illustrates an example encoder.

[0018] FIG. 7 is a block diagram that illustrates an example decoder.

[0019] FIG. 8 is a schematic diagram of an example encoder.

[0020] FIG. 9 is a flowchart for an example method of video processing.

DETAILED DESCRIPTION

[0021] It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or yet to be developed. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

1. Initial discussion

[0022] This document is related to image/video system and coding technologies. Specifically, this disclosure is related to a method to verify the image/video integrity. This includes signalling if the image/video has been modified from its certified source. The method applies to any video codec used for encoding of the video bitstream, and also applies to region-based content trustworthiness verification. The ideas may be applied individually or in various combinations for video bitstreams coded by any codec, such as the versatile video coding (WC) 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), 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 -net work post-filter characteristics (NNPFC), Picture Parameter Set (PPS), Picture Unit (PU), Random Access Skipped Leading (RASL). Supplemental Enhancement Information (SEI), Step-wise Temporal Sublayer Access (STSA). uniform resource identifier (URI), Video Coding Layer (VCL), versatile supplemental enhancement information (Rec. ITU- T H.274 | ISO/IEC 23002-7) (VSEI), Video Usability Information (VUI), versatile video coding (Rec. ITU-T H.266 | ISO/IEC 23090-3) (WC)

3.1 Further Discussion

3.1 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) 11 J standards. Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized.

[0025] The Versatile Video Coding (WC) standard (ITU-T H.266 | ISO/IEC 23090-3) [2] and the associated Versatile Supplemental Enhancement Information for coded video bitstreams (VSEI) standard (ITU-T H.274 | ISO/IEC 23002-7) [3] 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.

3.2. SEI messages in general and in WC and VSEI

[0026] SEI messages assist in processes related to decoding, display or other purposes. However. SEI 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 check bitstream conformance.

[0027] Annex D of WC specifies syntax and semantics for SEI message payloads for some SEI messages, and/or 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 Image/video tempering and deepfakes

[0028] An image/video file contains necessary information for reconstruction and related standards can guarantee the image/video can be reconstructed without any ambiguity. However, a standardized device cannot tell if the image/video has been tempered or not. With the development of deep neural network, image/video tempering is more difficult to determine. The following definition is used herein for the term deepfake. [0029] Deepfakes (a portmanteau of "deep learning" and "fake") are media that take a person in an existing image or video and replace them with someone else's likeness using artificial neural networks. They often combine and superimpose existing media onto source media using machine learning techniques known as autoencoders and generative adversarial networks (GANs). Deepfakes have garnered widespread attention for their uses in celebrity pornographic videos, revenge pom, fake news, hoaxes, and financial fraud. This has elicited responses from both industry and government to detect and limit their use.

3.4. Image/video applications requiring verification

[0030] Applications that might need verifications include:

1. Telemedicine. For safety reason, it is desired that a related medical image/video can be verified, e.g., if it is from a certified source.

2. Image/video recording with legal effectiveness or legal enforcement. Once the image/video is recorded, it can be told if the original image/video has been tempered. Thus, any image/video that shows legal effectiveness should pass the test to tell if the video is original or not.

3.5 Secure hash algorithms

[0031] The Secure Hash Algorithms (SHA) are a family of cryptographic hash functions published by the National Institute of Standards and Technology (NIST) as a U.S. Federal Information Processing Standard (FIPS), including:

[0032] SHA-0: A retronym applied to the original version of the 160-bit hash function published in 1993 under the name "SHA". It was withdrawn shortly after publication due to an undisclosed "significant flaw" and replaced by the slightly revised version SHA-1.

[0033] SHA-1 : A 160-bit hash function which resembles the earlier message digest five (MD5) algorithm. This was designed by the National Security Agency (NSA) to be part of the Digital Signature Algorithm. Cryptographic weaknesses were discovered in SHA-1, and the standard was no longer approved for most cry ptographic uses after 2010.

[0034] SHA-2: A family of two similar hash functions, with different block sizes, known as SHA-256 and SHA-512. They differ in the word size; SHA-256 uses 32-byte words where SHA-512 uses 64-byte words. There are also truncated versions of each standard, known as SHA-224, SHA-384, SHA-512/224 and SHA-512/256. These were also designed by the NSA.

[0035] SHA-3: A hash function formerly called Keccak, chosen in 2012 after a public competition among non-NSA designers. It supports the same hash lengths as SHA-2, and its internal structure differs significantly from the rest of the SHA family.

[0036] The corresponding standards are FIPS PUB 180 (original SHA). FIPS PUB 180-1 (SHA-1), FIPS PUB 180-2 (SHA-1, SHA-256, SHA-384, and SHA-512). NIST has updated Draft FIPS Publication 202, SHA-3 Standard separate from the Secure Hash Standard (SHS). 3.6 File verification

[0037] File verification is the process of using an algorithm for verifying the integrity of a computer file. This can be done by comparing two files bit-by-bit, but requires two copies of the same file, and may miss systematic corruptions which might occur to both files. Another approach is to generate a hash of the copied file and comparing that to the hash of the original file.

[0038] The verification process may include integrity verification and authenticity verification. File integrity can be compromised, usually referred to as the file becoming corrupted. A file can become corrupted by a variety of ways: faulty storage media, errors in transmission, write errors during copying or moving, software bugs, and so on. Hash-based verification ensures that a file has not been corrupted by comparing the file's hash value to a previously calculated value. If these values match, the file is presumed to be unmodified. Due to the nature of hash functions, hash collisions may result in false positives, but the likelihood of collisions is often negligible with random corruption. It is often desirable to verify that a file hasn't been modified in transmission or storage by untrusted parties, for example, to include malicious code such as viruses or backdoors. To verify the authenticity, a classical hash function is not enough as they are not designed to be collision resistant; it is computationally trivial for an attacker to cause deliberate hash collisions, meaning that a malicious change in the file is not detected by a hash comparison. In cryptography, this attack is called a preimage attack. For this purpose, cryptographic hash functions are employed often. As long as the hash sums caimot be tampered with — for example, if they are communicated over a secure channel — the files can be presumed to be intact. Alternatively, digital signatures can be employed to assure tamper resistance.

[0039] There are certain file formats that can support file verification, for example, a checksum file. A checksum file is a small file that contains the checksums of other files. There are a few well-known checksum file formats. Several utilities, such as md5deep. can use such checksum files to automatically verify an entire directory of files in one operation. The particular hash algorithm used is often indicated by the file extension of the checksum file. The " shal " file extension indicates a checksum file containing 160-bit SHA-1 hashes in shalsum format. The " md5" file extension, or a file named "MD5SUMS", indicates a checksum file containing 128-bit MD5 hashes in md5sum format. The ".sfv" file extension indicates a checksum file containing 32-bit CRC32 checksums in simple file verification format. The "crc.list" file indicates a checksum file containing 32-bit CRC checksums in brik format. As of 2012, best practice recommendations is to use SHA-2 or SHA-3 to generate new file integrity digests; and to accept MD5 and SHA-1 digests for backward compatibility if stronger digests arc not available. The theoretically weaker SHA-1, the weaker MD5, or much weaker CRC were previously commonly used for file integrity checks. CRC checksums cannot be used to verify the authenticity of files, as CRC32 is not a collision resistant hash function - even if the hash sum file is not tampered with, it is computationally trivial for an attacker to replace a file with the same CRC digest as the original file, meaning that a malicious change in the file is not detected by a CRC comparison. 3.7. Content worthiness verification

[0040] One example method for content worthiness verification is through the definition and use of three SEI messages, as follows:

3.7.1. Trustworthy content initialization SEI message

[0041] The trustworthy content initialization SEI message, trustworthy content selection SEI message, and trustworthy content verification SEI message provide a mechanism for verifying that the coded video has been produced by a trustworthy content provider. It should be noted that the trustworthy content initialization SEI message, trustworthy content selection SEI message, and trustworthy content verification SEI message may also be referred to as 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, respective!}'. The trustworthy' content initialization SEI message provides information about the secure hash algorithm used for calculating message digests, which are used together with the digital signature present in trustworthy content verification SEI messages to verify the trustw orthiness of the 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. [0042] If any trustworthy content initialization SEI message, trustworthy content selection SEI message, or trustworthy content verification SEI message is present in a coded video sequence, it is a requirement of bitstream conformance that a trustworthy content initialization SEI message is present in the instantaneous decoding refresh (IDR) access unit and all access units of the coded video sequence that contain a clean random access (CRA) picture. It is a requirement of bitstream conformance that any trustworthy content selection and trustworthy content verification SEI message in an access unit is preceded by a trustworthy content initialization SEI message. [0043] The trustworthy content initialization SEI message applies to the current coded picture and all following coded pictures until one or more of the follow ing conditions are true:

- The bitstream ends.

- A new' coded video sequence begins.

- A new⁷ trustworth}' content initialization SEI message is received. [0044] twci hash method type indicates the secure hash algorithm that is used to calculate message digests for subsets of VCL NAL units of the coded video sequence. Based on these message digests and the digital signatures present in trustworthy content verification SEI messages, a decoder can verily that the coded video was produced by the content originator indicated by the syntax elements twci use key register idx flag, twei key source uri, and, if twci key register idx flag is equal to 1 , twci key register idx. The supported values for the syntax element twci hash method type, the block size used for calculating the message digest, and the size of the calculated message digests are specified in Table 1. Values of tw ci hash method type that are not listed in the table 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 ignore trustworthy initialization SEI messages that contain reserved values for twci hash method type. The secure hash algorithms listed in Table 1 are specified in the ‘‘Secure Hash Standard" FIPS PUB 180-4.

Table 1 - Supported values of twci hash method type

[0045] twci num verification substreams minusl plus 1 indicates the number of substreams for which message digests are calculated and signatures may be present in following trustworthy content verification SEI messages.

[0046] The variable NumVerificationSubstream is derived as:

NumVerificationSubstream = twci num verification substreams minusl + 1.

[0047] twci use key register idx flag equal to 1 indicates that the URI contained in twci key source uri specifies a register of certificates and the syntax element twci key register idx is present in the SEI message, twci usc kcy rcgistcr idx llag equal to 0 indicates that the URI contained in twci key source uri specifies a certificate and the syntax element twei key register idx is not present in the SEI message.

[0048] twei key _source_uri contain a URI with syntax and semantics as specified in Internet Engineering

Task Force (IETF) Internet Standard 66. If twci use key register idx flag is equal to 0, the URI identifies the certificate of the content provider that can be used for verifying the signatures present in following trustworthy verification SEI messages; otherwise (if twci 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 trustworthy verification SEI messages is indicated by twci_key_register_idx.

[0049] twci key register idx contains an index that specifies the certificate of the content provider, in the certificate register indicated by twci key source uri, which can be used for verifying the signatures present in following trustworthy verification SEI messages.

[0050] The certificate indicated by the syntax elements twci use key register idx flag, twci key source uri, and, if twci use key register idx flag is equal to 1, twci key register idx shall specify a digital signature method, with associated parameters (if applicable), and the public key of the content provider. 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” FIPS 186-5 is used.

[0051] When a trustworthy content initialization SEI message is received, the calculation of NumVerificationSubstream message digests is initialized according to the specification in FIPS PUB 180-4 for the specified twei hash method type. Each VCL NAL unit following the trustworthy content initialization SEI message is associated to one of the NumVerificationSubstream message digests; the verification substream id is either indicated by the trustw orthy content selection SEI message or, if no trustworthy content selection SEI message is present for a coded picture, 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 twci num verification substreams minusl, inclusive, is obtained by concatenating all 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 1 depending on the value of twei hash method type. For each VCL NAL unit, the associated message digest is updated according to the algorithm specified in FIPS PUB 180-4 for the specified twei hash method type. Note that, since the message digests are calculated for the concatenation of all VCL NAL units for a verification substream, some of the processing blocks typically span over two or more successive VCL NAL units.

3.7.2. Trustworthy content selection SEI message

[0052] The trustworthy content selection SEI message provides a mechanism for associating coded pictures with one of the verification substreams indicated in a trustworthy content initialization SEI message.

[0053] It is a requirement of bitstream conformance that any trustworthy content selection SEI message is preceded by a trustworthy content initialization SEI message in the same coded video sequence.

[0054] twcs vcrification substrcam id indicates the verification substrcam to w hich the VCL NAL units of the current coded picture are assigned to. When a trustworthy content initialization SEI message was present in the current coded video sequence, but no trustw orthy content selection SEI message is present for a coded picture, the value of twcs verification substream id is inferred to be equal to 0. The value of twcs verification substream id shall be in the range from 0 to twci num verification substreams minusl, inclusive.

[0055] The message digest for the verification substream with id equal to twcs verification substream id is updated with the VCL NAL units of the current coded picture according to the twci hash method type specified in the preceding trustworthy content initialization SEI message.

3.7.3. Trustworthy content verification SEI message

[0056] The trustworthy content verification SEI message provides a mechanism for verifying the trustworthiness of video content.

[0057] It is a requirement of bitstream conformance that any trustworthy content verification SEI message is preceded by a trustworthy content initialization SEI message in the same coded video sequence.

[0058] When the coded video sequence includes a trustworthy content initialization SEI message, it is a requirement of bitstream conformance that the last coded picture of a verification substream in the coded video sequence is associated with a trustworthy content verification SEI message.

[0059] twcs verification substream id indicates the verification substream to which the SEI message applies.

[0060] twcv signature length in octets minus 1 plus 1 specifies the length of the syntax element twcv signature in octets (one octet comprises 8 bits).

[0061] twcv signature contains the digital signature for the verification substream indicated by twcs verification substream id, which is either transmitted in a trustworthy content selection SEI message preceding the trustworthy content verification SEI message in the same access unit or inferred to be equal to 0.

[0062] With VerificationSubstreamld being the value of twcs verification substream id associated with the trustworthy content verification SEI message, the verification comprises the following ordered steps:

1. The calculation of the message digest referred to as CurrDigest is finalized as follows:

- The concatenation of the VCL NAL units for the verification substream with id equal to VerificationSubstreamld is padded according to the specification in FIPS PUB 180-4. Note that it is sufficient to pad the last VCL NAL unit of the verification substream. - The calculation of the message digest CurrDigest is finalized according to the specification in FIPS PUB 180-4. The length (in bits) of the message digest is given in Table 1.

2. The reference message digest RefDigest is determined as follows:

- If VerificationSubstreamld is greater than 0, the reference message digest RefDigest is the last calculated message digest for the verification substream with id equal to VerificationSubstreamld - 1. It is a requirement of bitstream conformance that any trustworthy content verification SEI associated with verification substream id equal to VerificationSubstreamld - 1 is present before the trustworthy content verification SEI message with verification substrcam id equal to VerificationSubstreamld.

- Otherwise, if the current trustworthy content verification SEI message is the first trustworthy content verification SEI with verification id equal to 0 in the coded video sequence and the preceding coded video sequence did not contain any trustworthy 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 comprises DigestSize bits equal to 1, where DigestSize is the size of the message digest as specified in Table 1.

- Otherwise, the reference message digest RefDigest is the last calculated message digest for the verification substream with id equal to 0.

3. The identification string IdString is constructed by concatenating the binary representations of the reference message digest RefDigest, the current message digest, and the twei hash method type, as illustrated in FIG. 1.

[0063] FIG. 1 is a block diagram showing an example construction of identification string IdString 100.

[0064] The number of bits for RefDigest is determined by the value of twei hash method type which was valid when calculating the value of RefDigest, the number of bits for CurrDigest is determined by the current value of Wei hash method type, and the value of twei hash method type is represented with 8 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 twci use key register idx flag, twci_key_source_uri, and, if twci use key register idx flag is equal to 1, twei key register idx.

[0065] NOTE 1 - Since the bitstring used for signature verification includes the RefDigest, it cannot only be verified that the VCL NAL units used for calculated the current message digest arc correct, but it can additionally be verified that neither additional VCL NAL units were added to the bitstream nor VCL NAL units were removed from the bitstream.

[0066] NOTE 2 - When a decoder times into a bitstream, the IdString constructed for the first trustworthy content verification SEI message cannot be verified, because the value of RefDigest cannot be calculated correctly. But starting from the second trustworthy content verification SEI message, the signatures can be verified. [0067] After verification, the message digest for the verification substream with id equal to VerificationSubstreamld is reinitialized according to the specification in FIPS PUB 180-4 for the specified twci hash method type.

4. Technical problems solved by disclosed technical solutions

[0068] An example design for content worthiness verification through the definition and use of three SEI messages has the following problems:

[0069] First, the method can only be used for verifying the integrity of the VCL NAL units. However, parameter set NAL units, and. in the context of WC. picture header NAL units also affect the decoding results.

[0070] Second, it is specified that, if any trustworthy content initialization SEI message, trustworthy content selection SEI message, or trustworthy content verification SEI message is present in a coded video sequence, it is a requirement of bitstream conformance that a trustworthy content initialization SEI message is present in the IDR access unit and all access units of the coded video sequence that contain a CRA picture. However, a CLVS or CVS or a bitstream in an HEVC or WC bitstream may not even have an IDR picture. Furthermore, an access unit or a picture unit containing a recover}- point SEI message (in the context of AVC and HEVC) can also be used a random access point.

[0071] Third, the method does not provide region-based content worthiness verification.

5. A listing of solutions and embodiments

[0072] To solve 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) To solve problem 1, in one example, it is specified that all picture header NAL units (when present), parameter set NAL units, and VCL NAL units of the picture unit arc included in the calculation of the hash of the selected substream in bitstream order. For simplicity, the term "video coding NAL unit" is used to refer to a NAL unit that is a VCL NAL unit, a picture header NAL unit (in WC). a picture parameter set NAL unit (in AVC, HEVC, and WC), a sequence parameter set NAL unit (in AVC, HEVC, and WC), a video parameter set NAL unit (in HEVC and WC), or an adaptation parameter set (in WC). In an alternative, the term "video coding NAL unit" is used to refer to a NAL unit that is a VCL NAL unit or a picture header NAL unit (in WC). In another alternative, the term "video coding NAL unit" is used to refer to a NAL unit that is a VCL NAL unit, a picture header NAL unit (in WC). a picture parameter set NAL unit (in AVC, HEVC. and WC), a sequence parameter set NAL unit (in AVC, HEVC, and WC), or an adaptation parameter set (in WC). a. In one example, it is specified that, the trustworthy content initialization SEI message provides information about the secure hash algorithm used for calculating message digests, which are used together with the digital signature present in trustworthy content verification SEI messages to verify the trustworthiness of the video coding NAL units present in the CLVS. b. In one example, it is specified that twci hash method type indicates the secure hash algorithm that is used to calculate message digests for subsets of the video coding NAL units of the CLVS. c. In one example, it is specified that each video coding NAL unit following the trustworthy content initialization SEI message is associated to one of the NumVerificationSubstream message digests; the verification substream id is either indicated by the trustworthy content selection SEI message or, if no trustworthy content selection SEI message is present for a coded picture, inferred to be equal to 0. d. In one example, it is specified that the message used for calculating the k-th message digest, with k being in the range from 0 to twci num verification substreams minusl, inclusive, is obtained by concatenating all video coding NAL units associated with the k-th verification subsfream. e. In one example, it is specified that, for each video coding NAL unit, the associated message digest is updated according to the algorithm specified in FIPS PUB 180-4 for the specified twci hash method type. Note that, since the message digests are calculated for the concatenation of all video coding NAL units for a verification substream, some of the processing blocks typically span over two or more successive video coding NAL units. f. In one example, it is specified that twcs verification substream id indicates the verification substream to w hich video coding NAL units of the current picture unit are assigned to. g. In one example, it is specified that the message digest for the verification subsfream with ID equal to twcs verification substream id is updated with the video coding NAL units of the current picture unit according to the twci hash method type specified in the preceding trustworthy content initialization SEI message. h. In one example, it is specified that the concatenation of the video coding NAL units for the verification substream with ID equal to VerificationSubstreamld is padded according to the specification in FIPS PUB 180-4. Note that it is sufficient to pad the last video coding NAL unit of the verification substream. i. In one example, it is specified that, since the bitstring used for signature verification includes the RefDigest. it cannot only be verified that the video coding NAL units used for calculated the current message digest are correct, but it can additionally be verified that neither additional video coding NAL units were added to the bitstream nor video coding NAL units were removed from the bitstream. j. Additionally, in one example, NAL units that contain certain types of SEI messages are included in the calculation of the hash. i. In one example, NAL units that contain SEI messages related to timing information are included in the calculation of the hash. ) To solve problem 2, in one example, it is specified that, if any trustw orthy content initialization SEI message, trustworthy content selection SEI message, or trustworthy content verification SEI message is present in a CLVS, it is a requirement of bitstream conformance that a trustworthy content initialization SEI message is present in the first picture unit of the CLVS in decoding order and in all picture units of the CLVS that contain a CRA picture (in the context of HEVC and HEVC). a. In one example, it is specified that, if any trustworthy content initialization SEI message, trustworthy content selection SEI message, or trustworthy content verification SEI message is present in a CLVS, it is a requirement of bitstream conformance that a trustworthy content initialization SEI message is present in the first picture unit of the CLVS in decoding order and in all picture units of the CLVS that contain a CRA picture (in the context of HEVC and HEVC) or a recovery point SEI message (in the context of AVC and HEVC). ) To solve problem 3, in one example, it is specified that a digital signature, e.g., the one represented by the syntax element twev signature, may be only for a region of a picture, instead of being always for an entire picture. a. In one example, a syntax element indicating a region ID may be added to the trustworthy content selection SEI message syntax and the trustworthy content verification SEI message syntax, and the SEI messages carries information for one region only. i. In one example, it is specified that, if the substream ID S with region ID R is not equal to 0, the related segment is the substream with substream ID equal to S-l and region ID equal to R. If the substream ID with region ID R is equal to 0, the related segment is the previous substream in bitstream order w ith substream ID equalt to 0 and region ID equal to R. b. In one example, a flag, e,g., named twcs substream is a region flag, indicating whether the region is an independently coded region may be added to the trustworthy content selection SEI message sy ntax. i. In one example, when the flag is equal to 1, the region is an independently coded subpicture in WC, a motion-constrained tile set in HEVC, or a motion-constrained slice group in AVC. c. In one example, the region is an independently- coded subpicture in WC, a motion-constrained tile set in HEVC. or a motion-constrained slice group in AVC. d. In one example, the region is a coded subpicture in WC, a tile in WC or HEVC, or a set of slices covering a rectangular region. e. In one example, when the region is a coded subpicture in WC, the region ID may be specified to be equal to the subpicture ID. f. In one example, when the region is a tile in WC or HEVC, the region ID may be specified to be equal to the tile ID. g. In one example, syntax elements indicating the region location (e.g., syntax elements indicating the size and position of the region or region id or row/column indices) may- be added to either or both of the trustworthy content selection SEI message syntax and the trustworthy content verification SEI message syntax. h. In one example, the region could be a region-of-interest or a subpicture or a slice/tile/row or multiple rows/columns. i. In one example, a loop may be added to either or both of the trustworthy content selection SEI message syntax and the trustworthy content verification SEI message syntax, such that the SEI messages carries information for multiple regions in a picture, each loop for one region.

4) In the above items, the hash calculation may be applied on the raw byte sequence payload of related NAL units. a. In one example, the hash calculation may be applied on the related NAL units with NAL unit header and/or rbsp_trailing_bits( ) removed. i. Alternatively, it may be specified a certain number of first and/or last bits of the NAL unit data are not included in the calculation of the hash value.

6. References

[1] ITU-T and ISO/IEC, ‘'High efficiency video coding⁷’. Rec. ITU-T H.265 | ISO/IEC 23008-2 (in force edition).

[2] ITU-T and ISO/IEC, ‘'Versatile Video Coding”, Rec. ITU-T H.266 | ISO/IEC 23090-3.

[3] ITU-T and ISO/IEC, '‘Versatile Supplemental Enhancement Information Messages for Coded Video Bitstreams”, Rec. ITU-T Rec. H.274 | ISO/IEC 23002-7.

[0073] FIG. 2 is a block diagram showing an example video processing system 4000 in which various techniques 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.

[0074] The system 4000 may include a coding component 4004 that may implement the various coding or encoding methods described in the present document. 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.

[0075] Examples of a peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HDMI) or Displayport, and so on. Examples of storage interfaces include serial advanced technology attachment (SATA), peripheral component interconnect (PCI), integrated drive electronics (IDE) interface, and the like. The techniques described in the present document may be embodied in various electronic devices such as mobile phones, laptops, smartphones or other devices that are capable of performing digital data processing and/or video display.

[0076] FIG. 3 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 document. The memory (memories) 4104 may be used for storing data and code used for implementing the methods and techniques described herein. The video processing circuitry 4106 may be used to implement, in hardware circuitry, some techniques described in the present document. In some embodiments, the video processing circuitry 4106 may be at least partly included in the processor 4102, e.g., a graphics co-processor.

[0077] FIG. 4 is a flowchart for an example method 4200 of video processing. The method 4200 determines to include all picture header network abstraction layer (NAL) units, parameter set NAL units, and video coding layer (VCL) NAL units of a picture unit in a calculation of a hash of a selected substream in bitstream order at step 4202. A conversion between a visual media data and a bitstream based on the hash at step 4204. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

[0078] 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.

[0079] FIG. 5 is a block diagram that illustrates an example video coding system 4300 that may utilize the techniques 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. [0080] 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 may⁷ 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.

[0081] 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.

[0082] 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 (WC) standard and other current and/or further standards.

[0083] FIG. 6 is a block diagram illustrating an example of video encoder 4400, which may be video encoder 4314 in the system 4300 illustrated in FIG. 5. Video encoder 4400 may be configured to perform any or all of the techniques of this disclosure. The video encoder 4400 includes a plurality of functional components. The techniques 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 techniques described in this disclosure. [0084] 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, 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.

[0085] In other examples, video encoder 4400 may include more, fewer, or different functional components. In an example, prediction unit 4402 may include an intra block copy (IBC) unit. The IBC unit may' perform prediction in an IBC mode in which at least one reference picture is a picture where the current video block is located. [0086] 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 separate!} for purposes of explanation.

[0087] 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.

[0088] Mode select unit 4403 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra or inter coded block to a residual generation unit 4407 to generate residual block data and to a reconstruction unit 4412 to reconstruct the encoded block for use as a reference picture. In some examples, mode select unit 4403 may select a combination of intra and inter prediction (CIIP) mode in which the prediction is based on an inter prediction signal and an intra prediction signal. Mode select unit 4403 may also select a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter prediction.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] In another example, motion estimation unit 4404 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD). The motion vector difference indicates a difference betw een the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 4500 max’ use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0096] 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.

[0097] 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. [0098] 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.

[0099] 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. [00100] Transform processing unit 4408 may generate one or more transform coefficient video blocks for the current video block by’ applying one or more transfonns to a residual video block associated with the current video block.

[00101] After transform processing miit 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.

[00102] 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.

[00103] After reconstruction unit 4412 reconstructs the video block, the loop filtering operation may be performed to reduce video blocking artifacts in the video block.

[00104] 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.

[00105] FIG. 7 is a block diagram illustrating an example of video decoder 4500 which may be video decoder 4324 in the sy stem 4300 illustrated in FIG. 5. The video decoder 4500 may be configured to perform any or all of the teclmiques of this disclosure. In the example shown, the video decoder 4500 includes a plurality of functional components. The techniques 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 teclmiques described in this disclosure.

[00106] 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.

[00107] Entropy decoding unit 4501 may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data). Entropy decoding unit 4501 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 4502 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 4502 may, for example, determine such information by performing the AMVP and merge mode.

[00108] 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 may⁷ be included in the sy ntax elements.

[00109] 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.

[00110] 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.

[00111] 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.

[00112] 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 arc 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.

[00113] FIG. 8 is a schematic diagram of an example encoder 4600. The encoder 4600 is suitable for implementing the techniques of WC. 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 utilize the original samples of the current picture to reduce the mean square errors between the original samples and the reconstructed samples by adding an offset and by applying a finite impulse response (FIR) filter, respectively, with coded side information signaling the offsets and filter coefficients. The ALF 4606 is located at the last processing stage of each picture and can be regarded as a tool trying to catch and fix artifacts created by the previous stages.

[00114] The encoder 4600 further includes an intra prediction component 4608 and a motion estimation/compensation (ME/MC) component 4610 configured to receive input video. The intra prediction component 4608 is configured to perform intra prediction, while the ME/MC component 4610 is configured to utilize reference pictures obtained from a reference picture buffer 4612 to perform inter prediction. Residual blocks from inter prediction or intra prediction are fed into a transform (T) component 4614 and a quantization (Q) component 4616 to generate quantized residual transform coefficients, which are fed into an entropy coding component 4618. The entropy coding component 4618 entropy codes the prediction results and the quantized transform coefficients and transmits the same toward a video decoder (not shown). Quantization components output from the quantization component 4616 may be fed into an inverse quantization (IQ) components 4620, an inverse transform component 4622, and a reconstruction (REC) component 4624. The REC component 4624 is able to output images to the DF 4602. the SAO 4604, and the ALF 4606 for filtering prior to those images being stored in the reference picture buffer 4612.

[00115] FIG. 9 is a flowchart for an example method 4700 of video processing. The method 4700 determines a digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture at step 4702. A conversion between a visual media data and a bitstream is perfomed based on the digital signature at step 4704. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

[00116] It should be noted that the method 4700 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 4700. Further, the method 4700 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 4700.

[00117] A listing of solutions preferred by some examples is provided next.

[00118] The following solutions show examples of techniques discussed herein.

[00119] 1. A method for processing media data comprising: determining to include all picture header network abstraction layer (NAL) units, parameter set NAL units, and video coding layer (VCL) NAL units of a picture unit in a calculation of a hash of a selected substream in bitstream order; and performing a conversion between a visual media data and a bitstream based on the hash.

[00120] 2. The method of solution 1, wherein video coding NAL unit indicates a NAL unit that is a VCL

NAL unit, a picture header NAL unit, a picture parameter set NAL unit, a sequence parameter set NAL unit, a video parameter set NAL unit, or an adaptation parameter set, or wherein video coding NAL unit indicates a NAL unit that is a VCL NAL unit or a picture header NAL unit, or wherein video coding NAL unit indicates a NAL unit that is a VCL NAL unit, a picture header NAL unit, a picture parameter set NAL unit, a sequence parameter set NAL unit, or an adaptation parameter set.

[00121] 3. The method of any of solutions 1-2, wherein a trustworthy content initialization supplemental enhancement information (SEI) message provides information about a secure hash algorithm used for calculating message digests, which are used together with a digital signature present in trustworthy content verification SEI messages to verily trustworthiness of the video coding NAL units present in the coded layer video sequence (CLVS).

[00122] 4. The method of any of solutions 1-3, wherein twei hash method type indicates a secure hash algorithm that is used to calculate message digests for subsets of the video coding NAL units of the CLVS.

[00123] 5. The method of any of solutions 1 -4, wherein each video coding NAL unit following a trustworthy content initialization SEI message is associated to one of the NumVerificationSubstream message digests, and wherein a verification substream identifier is either indicated by a trustworthy content selection SEI message or, when no trustworthy content selection SEI message is present for a coded picture, inferred to be equal to 0.

[00124] 6. The method of any of solutions 1-5, wherein a message used for calculating a k-th message digest, with k being in the range from 0 to twci num verification substreams minusl, inclusive, is obtained by concatenating all video coding NAL units associated with tire k-th verification substream.

[00125] 7. The method of any of solutions 1-6, wherein for each video coding NAL mrit, an associated message digest is updated according to an algorithm for a specified twci hash method type, and wherein since the message digests are calculated for the concatenation of all video coding NAL mrits for a verification substream, some of the processing blocks span over two or more successive video coding NAL units.

[00126] 8. The method of any of solutions 1-7, wherein twcs verification substream id indicates the verification substream to which video coding NAL units of the current picture unit are assigned to.

[00127] 9. The method of any of solutions 1-8, wherein the message digest for the verification substream with ID equal to twcs verification substream id is updated with the video coding NAL mrits of the current picture unit according to the twci hash method type specified in the preceding trustworthy content initialization SEI message.

[00128] 10. The method of any of solutions 1-9, wherein the concatenation of the video coding NAL mrits for the verification substream with identifier (ID) equal to VerificationSubstreamld is padded according, and wherein the last video coding NAL unit of the verification substream is padded.

[00129] 11. The method of any of solutions 1-10, wherein since the bitstring used for signature verification includes the RefDigest, a verification is made that the video coding NAL units used for calculating the current message digest are correct, and a verification is made that neither additional video coding NAL mrits were added to the bitstream nor video coding NAL units were removed from the bitstream.

[00130] 12. The method of any of solutions 1-11, wherein NAL mrits that contain certain types of SEI messages are included in the calculation of the hash, or wherein NAL mrits that contain SEI messages related to timing information are included in the calculation of the hash.

[00131] 13. The method of any of solutions 1-12, wherein, when any trustworthy content initialization SEI message, trustworthy content selection SEI message, or trustworthy content verification SEI message is present in a CLVS, a trustworthy content initialization SEI message must be present in the first picture unit of the CLVS in decoding order and in all picture mrits of the CLVS that contain a clean random access (CRA) picture for bitstream conformance.

[00132] 14. The method of any of solutions 1-13, wherein when any trustworthy content initialization SEI message, trustworthy content selection SEI message, or trustworthy content verification SEI message is present in a CLVS, a trustworthy content initialization SEI message must be present in the first picture unit of the CLVS in decoding order and in all picture units of the CLVS that contain a CRA picture or a recovery point SEI message for bitstream conformance. [00133] 15. The method of any of solutions 1-14, wherein a digital signature, represented by the syntax element twcv signature, may be only for a region of a picture, instead of for an entire picture.

[00134] 16. The method of any of solutions 1-15, wherein a syntax clement indicating a region ID is added to the trustworthy content selection SEI message syntax and the trustworthy content verification SEI message syntax, and the SEI messages carries information for one region only, or wherein when the substream ID S with region ID R is not equal to 0, the related segment is the substream with substream ID equal to S-l and region ID equal to R, or wherein when the substream ID with region ID R is equal to 0, the related segment is the previous substream in bitstream order with substream ID equalt to 0 and region ID equal to R.

[00135] 17. The method of any of solutions 1-16, wherein a flag named twcs_substream_is_a_region_flag, indicating whether the region is an independently coded region is added to the trustworthy content selection SEI message sy ntax, or wherein when the flag is equal to 1, the region is an independently coded subpicture in versatile video coding (WC), a motion-constrained tile set in high efficiency' video coding (HEVC), or a motion-constrained slice group in advance video coding (AVC).

[00136] 18. The method of any of solutions 1-17, wherein a region is an independently coded subpicture in

WC, a motion-constrained tile set in HEVC, or a motion-constrained slice group in AVC.

[00137] 19. The method of any of solutions 1-18, wherein the region is a coded subpicture in WC, a tile in

WC or HEVC, or a set of slices covering a rectangular region.

[00138] 20. The method of any of solutions 1-19, wherein when the region is a coded subpicture in WC, the region ID may be specified to be equal to the subpicture ID.

[00139] 21. The method of any of solutions 1-20, wherein when the region is a tile in WC or HEVC, the region ID is specified to be equal to the tile ID.

[00140] 22. The method of any of solutions 1-21, wherein syntax elements indicating the region location are added to the trustworthy content selection SEI message syntax or the trustworthy content verification SEI message syntax.

[00141] 23. The method of any of solutions 1-23, wherein the region is a region-of-interest, a subpicturc. a slice, a tile, a row, multiple rows, or multiple columns.

[00142] 24. The method of any of solutions 1-23, wherein a loop is added to the trustworthy content selection

SEI message syntax or the trustw orthy content verification SEI message syntax, such that the SEI messages carries information for multiple regions in a picture, each loop for one region.

[00143] 25. The method of any of solutions 1-24, wherein the hash calculation is applied on the raw byte sequence payload of related NAL units.

[00144] 26. The method of any of solutions 1 -25, wherein the hash calculation is applied on the related NAL units with NAL unit header or rbsp_trailing_bits( ) removed, or wherein a certain number of first or last bits of the NAL unit data are not included in the calculation of the hash value. [00145] 27. 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 1-26.

[00146] 28. 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 1-26.

[00147] 29. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining to include all picture header network abstraction layer (NAL) units, parameter set NAL units, and video coding layer (VCL) NAL units of a picture unit in a calculation of a hash of a selected substream in bitstream order; and generating a bitstream based on the determining.

[00148] 30. A method for storing bitstream of a video comprising: determining to include all picture header network abstraction layer (NAL) units, parameter set NAL units, and video coding layer (VCL) NAL units of a picture unit in a calculation of a hash of a selected substream in bitstream order; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

[00149] 31. A method, apparatus, or system described in the present document.

[00150] The following solutions show further examples of techniques discussed herein.

[00151] 1. A method for processing media data comprising: determining a digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture; and performing a conversion between a visual media data and a bitstream based on the digital signature.

[00152] 2. The method of claim 1, wherein the content selection SEI message contains a syntax element containing an identifier (ID) indicating the single region to which the digital signature applies.

[00153] 3. The method of any of claims 1-2, wherein the ID indicating the single region is set equal to a subpicture ID.

[00154] 4. The method of any of claims 1-3, wherein the content selection SEI message is a digitally signed content selection SEI message.

[00155] 5. The method of any of claims 1 -4, wherein the single region of the picture is identified by a picture segment ID.

[00156] 6. The method of any of claims 1-5, wherein the content selection SEI message is a trustworthy content selection SEI message.

[00157] 7. The method of any' of claims 1-6, wherein when a substream ID of value S with region ID of value R is not equal to 0, a related segment is a substream with a substream ID equal to S-l and a region ID equal to R. [00158] 8. The method of any of claims 1 -7, wherein when the substream ID with region ID R is equal to 0, the related segment is a previous substream in bitstream order with a substream ID equalt to 0 and a region ID equal to R.

[00159] 9. The method of any of claims 1-8, wherein a trustworth}' content selection SEI message contains a flag indicating whether the single region is an independently coded region.

[00160] 10. The method of any of claims 1-9, wherein when the flag is equal to 1, the single region is an independently coded subpicture in versatile video coding (W C), a motion-constrained tile set in high efficiency video coding (HEVC), or a motion-constrained slice group in advance video coding (AVC).

[00161] 11. The method of any of claims 1-10, wherein the single region is an independently coded subpicture in WC, a motion-constrained tile set in HEVC, or a motion-constrained slice group in AVC.

[00162] 12. The method of any of claims 1-11, wherein the single region is a coded subpicture in WC, a tile in WC or HEVC, or a set of slices covering a rectangular region.

[00163] 13. The method of any of claims 1-12, wherein when the single region is a tile in WC or HEVC, a region ID for the single region is specified to be equal to a tile ID.

[00164] 14. The method of any⁷ of claims 1-13, wherein a trustworthy content selection SEI message or a trustworthy content verification SEI message includes syntax elements indicating a region location for the single region.

[00165] 15. The method of any of claims 1-14, wherein the single region is a region-of- interest, a subpicture, a slice, a tile, a row, multiple rows, or multiple columns.

[00166] 16. The method of any of claims 1-15, wherein a trustworthy content selection SEI message contains a loop such that the trustworthy content selection SEI messages carries information for multiple regions in a picture where each loop applies to one region.

[00167] 17. The method of any of claims 1-16, wherein a trustworthy content verification SEI message contains a loop, such that the trustworthy content verification SEI messages carries information for multiple regions in a picture where each loop applies to one region.

[00168] 18. The method of any of claims 1-17, wherein the conversion includes encoding the visual media data into the bitstream.

[00169] 19. The method of any of claims 1-17, wherein the conversion includes decoding the visual media data from the bitstream.

[00170] 20. An apparatus for processing video data comprising: a processor; and a non-transitory memory⁷ with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of claims 1-19.

[00171] 21. 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 1-19.

[00172] 22. 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 digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture; and generating a bitstream based on the determining.

[00173] 23. A method for storing bitstream of a video comprising: determining a digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

[00174] In the solutions described herein, an encoder may conform to the format rule by producing a coded representation according to the format rule. In the solutions described herein, a decoder may use the format rule to parse syntax elements in the coded representation with the knowledge of presence and absence of sy ntax elements according to the format rule to produce decoded video.

[00175] In the present document, 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.

[00176] The disclosed and other solutions, examples, embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g.. code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machinegenerated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.

[00177] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g.. one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[00178] The processes and logic flows described in this document 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., an field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

[00179] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory', media and memory' devices, including by way of example semiconductor memory devices, e.g., erasable programmable read-only memory' (EPROM), electrically' erasable programmable read-only' memory' (EEPROM), and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and compact disc read-only' memory (CD ROM) and Digital versatile disc-read only memory (DVD-ROM) disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[00180] While this patent document contains many specifics, these should not be construed as limitations on the scope of any subject matter or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular techniques. Certain features that are described in this patent document 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.

[00181] 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 this patent document should not be understood as requiring such separation in all embodiments.

[00182] 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 this patent document.

[00183] 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 arc 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.

[00184] 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.

[00185] 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 coimected 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

CLAIMS What is claimed is:

1 . A method for processing media data comprising: determining a digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture: and performing a conversion between a visual media data and a bitstream based on the digital signature.

2. The method of claim 1, wherein the content selection SEI message contains a syntax clement containing an identifier (ID) indicating the single region to which the digital signature applies.

3. The method of any of claims 1-2, wherein the ID indicating the single region is set equal to a subpicture ID.

4. The method of any of claims 1-3, wherein the content selection SEI message is a digitally signed content selection SEI message.

5. The method of any of claims 1 -4, wherein the single region of the picture is identified by a picture segment ID.

6. The method of any of claims 1-5, wherein the content selection SEI message is a trustworthy content selection SEI message.

7. The method of any of claims 1-6, wherein when a substream ID of value S with region ID of value R is not equal to 0, a related segment is a substream with a substream ID equal to S-l and a region ID equal to R.

8. The method of any of claims 1-7, wherein when the substream ID with region ID R is equal to 0, the related segment is a previous substream in bitstream order with a substream ID equalt to 0 and a region ID equal to R.

9. The method of any of claims 1-8, wherein a trustworthy content selection SEI message contains a flag indicating whether the single region is an independently coded region.

10. The method of any of claims 1 -9, wherein when the flag is equal to 1 , the single region is an independently coded subpicture in versatile video coding (WC), a motion-constrained tile set in high efficiency video coding (HEVC), or a motion-constrained slice group in advance video coding (AVC).

11. The method of any of claims 1-10. wherein the single region is an independently coded subpicture in WC, a motion-constrained tile set in HEVC, or a motion-constrained slice group in AVC.

12. The method of any of claims 1-11, wherein the single region is a coded subpicture in WC, a tile in WC or HEVC, or a set of slices covering a rectangular region.

13. The method of any of claims 1-12, wherein when the single region is a tile in WC or HEVC, a region ID for the single region is specified to be equal to a tile ID.

14. The method of any of claims 1-13, wherein a trustworthy content selection SEI message or a trustworthy content verification SEI message includes syntax elements indicating a region location for the single region.

15. The method of any of claims 1-14, wherein the single region is a region-of-interest, a subpicture, a slice, a tile, a row, multiple rows, or multiple columns.

16. The method of any of claims 1-15, wherein a trustworthy content selection SEI message contains a loop such that the trustworthy content selection SEI messages carries information for multiple regions in a picture where each loop applies to one region.

17. The method of any of claims 1-16, wherein a trustworthy content verification SEI message contains a loop, such that the trustworthy content verification SEI messages carries information for multiple regions in a picture where each loop applies to one region.

18. The method of any of claims 1-17, wherein the conversion includes encoding the visual media data into the bitstream.

19. The method of any of claims 1-17, wherein the conversion includes decoding the visual media data from the bitstream.

20. 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 1-19.

21. 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 1-19.

22. 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 digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture; and generating a bitstream based on the determining.

23. A method for storing bitstream of a video comprising: determining a digital signature in a content selection supplemental enhancement information (SEI) message applies to a single region of a picture; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.