Presence indication and necessity of generated pictures for generative face video SEI messages in a video bitstream

Abstract

A mechanism for processing video data is disclosed. The mechanism includes determining that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value [ i ]) where a value of the gfv_chroma_key_thr_value [ i ] shall be in a range of zero to 255. A conversion is performed between a visual media data and a bitstream based on the gfv_chroma_key_thr_value [ i ].

Description

Indication Of Presence And Necessity Of Generated Pictures For Generative Face Video (GFV) Supplemental Enhancement Information (SEI) Messages In A Video Bitstream CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority to and benefits of U.S. Provisional Patent Application No. 63 / 677,638, filed on July 31, 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 connected user devices capable of receiving and displaying video increases, the bandwidth demand for digital video usage is likely to continue to grow. SUMMARY

[0004] A first aspect relates to a method for processing media data comprising: determining that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; and performing a conversion between a visual media data and a bitstream based on the gfv_chroma_key_thr_value[ i ].

[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 that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; and generating a bitstream based on the indication.

[0008] A fifth aspect relates to a method for storing bitstream of a video comprising: determining that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chromakey threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; generating a bitstream based on the indication; 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 conjunction 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 illustrates a diagram of a generative face video compression scheme.

[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 another 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.

[0022] Section headings are used in the present document for ease of understanding and do not limit the applicability of techniques and embodiments disclosed in each section only to that section. Furthermore, H.266 terminology is used in some description only for ease of understanding and not for limiting scope of the disclosed techniques. As such, the techniques described herein are applicable to other video codec protocols and designs also. 1. Initial discussion

[0023] This document is related to video coding and signalling. Specifically, this disclosure is related to the indication of the presence and necessity of generative face video (GFV) supplemental enhancement information(SEI) messages in a coded video bitstream, a coded video sequence (CVS), or a coded layer video sequence (CLVS), and that decoding systems that do not support processing of GFV SEI messages shall ignore the coded video bitstream, the CVS, or the CLVS. This invention also involves specifying value ranges for some syntax elements in the GFV SEI message. The ideas may be applied individually or in various combinations, for video bitstreams coded by any codec, e.g., the versatile video coding (VVC) standard and / or the versatile supplemental enhancement information (SEI) messages for coded video bitstreams (VSEI) standard, and may also be applied in generative video systems other than a generative face video system. 2. Abbreviations

[0024] 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-network post-filter characteristics (NNPFC), picture parameter set (PPS), picture unit (PU), random access skipped leading (RASL) picture, supplemental enhancement information (SEI), step-wise temporal sublayer access (STSA), uniform resource identifier (URI), video coding layer (VCL), versatile supplemental enhancement information as described in Rec. ITU-T H.274 | ISO / IEC 23002-7 (VSEI), video usability information (VUI), versatile video coding as described in Rec. ITU-T H.266 | ISO / IEC 23090-3 (VVC). 3. Further discussion 3.1 Video coding standards

[0025] Video coding standards have evolved primarily through the development of International Telecommunication Union (ITU) telecommunication standardization sector (ITU-T) and International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC) standards. The ITU-T produced H.261 and H.263, ISO / IEC produced motion picture experts group (MPEG)-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262 / MPEG-2 Video and H.264 / MPEG-4 Advanced Video Coding (AVC) and H.265 / high efficiency video coding (HEVC) [1] standards. Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized. The Versatile Video Coding (VVC) 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 VVC 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. Conformingdecoders 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 VVC specifies syntax and semantics for SEI message payloads for some SEI messages, and specifies the use of the SEI messages and VUI parameters for which the syntax and semantics are specified in ITU-T H.274 | ISO / IEC 23002-7. 3.3 Generative face video SEI message

[0028] FIG.1 illustrates a diagram of a generative face video compression scheme 100. In the scheme, some base pictures, called key pictures, are coded using a video codec, e.g. VVC, and subsequent pictures include meta data of face features, e.g. head position, eye matrix representing the open-close status and level of eyes. A decoder uses a generative neural network to form a decoded video based on those key pictures and subsequent face feature data. Joint Video Experts Team (JVET)-AG2032-v2 [4] includes the specification of the generative face video SEI message, as follows. 8.36 Generative face video SEI message 8.36.1 Generative face video SEI message syntax generative_face_video ( payloadSize ) { Descriptor f idfor( c = 0; c < 3; c++ ) { gfv_chroma_key_value_present_flag[ c ] u(1)if( gfv_coordinate_z_abs[ i ] > 0 ) gfv_coordinate_z_sign_flag[ i ] u(1)if( gfv_matrix_type_idx[ i ] >= 7 ) gfv_num_matrices_minus1[ i ] ue(v)gfv_nn_payload_byte[ i ] b(8) }

[0029] The generative face video (GFV) SEI message carries facial parameters and indicates a facial parameter translator network, denoted as TranslatorNN( ), that may be used to convert various formats of facial parameters signalled in the SEI message into a particular facial parameter format supported by the decoding system. A face picture generator neural network, denoted as GenerativeNN( ), may be used to generate output pictures using the facial parameters translated into the particular format and previously decoded output pictures.

[0030] When a picture unit contains a GFV SEI message with a particular gfv_id value and gfv_base_pic_flag equal to 1, the picture in the picture unit is referred to as a base picture for that particular gfv_id value.

[0031] When a picture unit contains a GFV SEI message with a particular gfv_id value and gfv_base_pic_flag equal to 0, and the picture unit does not contain a GFV SEI message with that particular gfv_id value and gfv_base_pic_flag equal to 1, the picture in the picture unit is referred to as a driving picture for that particular gfv_id value.

[0032] When a picture unit contains a GFV SEI message with a particular gfv_id value, gfv_base_pic_flag equal to 0, and gfv_drive_pic_fusion_flag equal to 1, and the picture unit does not contain a GFV SEI message with that particular gfv_id value and gfv_base_pic_flag equal to 1, the picture in the picture unit is referred to as a fusion picture for that particular gfv_id value.

[0033] NOTE 1 – Facial parameters could be determined from source pictures prior to encoding.

[0034] NOTE 2 – Previously decoded output pictures input to GenerativeNN( ) may be a base picture (a decoded output picture that provides the reference texture from which the face pictures may be generated) and, optionally, a picture that can be fused by GenerativeNN( ) to improve background texture and facial details. When the current picture is not a base picture, the GFV SEI message may be used to generate a face picture based on the previously decoded base picture, the facial parameters conveyed by the GFV SEI message, and, optionally, the current decoded picture for fusion purpose.

[0035] Use of this SEI message requires the definition of the following variables: - Input and output picture width and height in units of luma samples, denoted herein by CroppedWidth and CroppedHeight, respectively. - Luma sample array baseCroppedYPic and chroma sample arrays baseCroppedCbPic and baseCroppedCrPic for a decoded output picture, denoted as BasePicture, corresponding to a source base picture. - Luma sample array driveCroppedYPic and chroma sample arrays driveCroppedCbPic and driveCroppedCrPic for a decoded output picture, denoted as DrivePicture, corresponding to a source driving picture. - Bit depth BitDepthYfor the luma sample array of the input and output pictures.- Bit depth BitDepthC for the chroma sample arrays, if any, of the input and output pictures. - A chroma format indicator, denoted herein by ChromaFormatIdc, as described in subclause 7.3.

[0036] The variables SubWidthC and SubHeightC are derived from ChromaFormatIdc as specified by Table 2.

[0037] gfv_id contains an identifying number that may be used to identify face feature information and specify a neural network that may be used as TranslatorNN( ). The value of gfv_id shall be in the range of 0 to 232− 2, inclusive. Values of gfv_id from 256 to 511, inclusive, and from 231to 232− 2, inclusive, are reserved for future use by ITU-T | ISO / IEC. Decoders conforming to this edition of this document encountering a GFV SEI message with gfv_id in the range of 256 to 511, inclusive, or in the range of 231to 232− 2, inclusive, shall ignore the SEI message.

[0038] gfv_cnt specifies a GFV SEI message instance count value for this gfv_id value within a picture unit.

[0039] The gfv_cnt of the first GFV SEI message, in decoding order, with a particular value of gfv_id within picture unit shall be equal to 0. When gfv_cnt assigned to currGfvCnt is greater than 0, a GFV SEI message with the same gfv_id value and gfv_cnt equal to currGfvCnt − 1 shall be present in the same picture unit and precede the current GFV SEI message in decoding order.

[0040] The value of gfv_cnt shall be in the range of 0 to 65535, inclusive.

[0041] gfv_base_pic_flag equal to 1 indicates that the current decoded output picture corresponds to a base picture. gfv_base_pic_flag equal to 0 indicates that the current decoded output picture does not correspond to a base picture or this SEI message does not specify syntax elements for a base picture. When gfv_base_pic_flag is not present, it is inferred to be equal to 0.

[0042] When a GFV SEI message is the first GFV SEI message, in decoding order, that has a particular gfv_id value within the current CLVS, the value of gfv_base_pic_flag shall be equal to 1.

[0043] When a GFV SEI message with a particular gfv_id value has gfv_base_pic_flag equal to 1, the base picture for that particular gfv_id value, which is the current cropped decoded picture, remains valid for the current decoded picture and all subsequent decoded pictures of the current layer, in output order, until the end of the current CLVS or up to but excluding the decoded picture that is within the current CLVS, follows the current decoded picture in output order, and is associated with a GFV SEI message having that particular gfv_id value and gfv_base_pic_flag equal to 1, whichever is earlier.

[0044] gfv_nn_present_flag equal to 1 indicates that a neural network that may be used as a TranslatorNN( ) is contained or indicated by the SEI message. gfv_nn_present_flag equal to 0 indicates that a neural network that may be used as a TranslatorNN( ) is not contained or indicated by the SEI message. When gfv_nn_present_flag is not present, it is inferred to be 0.

[0045] When a GFV SEI message with gfv_cnt equal to 0 is present in the first picture unit in a CLVS in decoding order, gfv_nn_present_flag shall be present and equal to 1.

[0046] When gfv_nn_present_flag is equal to 0 and TranslatorNN is referenced in the semantics of the GFV SEI message, the following constraint applies:

[0047] – If gfv_cnt is equal to 0, there shall be at least one GFV SEI message present in a preceding picture unit in output order in the current CLVS and having the same value of gfv_id as that in the current GFV SEI message and gfv_nn_present_flag equal to 1.

[0048] – Otherwise (gfv_cnt is greater than 0), there shall be at least one GFV SEI message that is present in either the current picture unit or a preceding picture unit in output order in the current CLVS and has the same value of gfv_id as that in the current GFV SEI message and gfv_nn_present_flag equal to 1.

[0049] When gfv_nn_present_flag is equal to 0 and TranslatorNN is referenced in the semantics of this SEI message, the following applies for deriving the applicable TranslatorNN:

[0050] – If gfv_cnt is greater than 0 and there exists one or more preceding GFV SEI messages in decoding order in the current picture unit that has the same value of gfv_id as that in the current GFV SEI message and gfv_nn_present_flag equal to 1, the applicable TranslatorNN is defined by the last preceding GFV SEI message in decoding order in the current picture unit that has the same value of gfv_id as that in the current GFV SEI message and gfv_nn_present_flag equal to 1.

[0051] – Otherwise, the applicable TranslatorNN is defined by a GFV SEI message that is present in the last preceding picture unit puB in output order in the current CLVS that has the same value of gfv_id as the current GFV SEI message and gfv_nn_present_flag equal to 1. When there are multiple such GFV SEI messages present in the picture unit puB that have the same value of gfv_id as the current GFV SEI message and gfv_nn_present_flag equal to 1, the applicable TranslatorNN is defined by the last of such GFV SEI messages in decoding order.

[0052] gfv_nn_base_flag, gfv_nn_mode_idc, gfv_nn_alignment_zero_bit_a, gfv_nn_tag_uri, gfv_nn_uri, gfv_nn_alignment_zero_bit_b, and gfv_nn_payload_byte[ i ] specify a neural network that may be used as a TranslatorNN( ). gfv_nn_base_flag, gfv_nn_mode_idc, gfv_nn_alignment_zero_bit_a, gfv_nn_tag_uri, gfv_nn_uri, gfv_nn_alignment_zero_bit_b, and gfv_nn_payload_byte[ i ] have the same syntax and semantics as nnpfc_base_flag, nnpfc_mode_idc, nnpfc_alignment_zero_bit_a, nnpfc_tag_uri, nnpfc_uri, nnpfc_alignment_zero_bit_b, and nnpfc_payload_byte[ i ], respectively.

[0053] When either of the following conditions is true, GFV SEI messages shall have the same SEI payload content:

[0054] – The GFV SEI messages are present in the same picture unit, have gfv_cnt equal to 0, have gfv_nn_base_flag present, and have the same value of gfv_id and gfv_nn_base_flag.

[0055] – The GFV SEI messages are present in the same picture unit, have the same value of gfv_cnt that is greater than 0, and have the same value of gfv_id.

[0056] gfv_chroma_key_info_present_flag equal to 1 indicates that the syntax elements gfv_chroma_key_value_present_flag[ c ] and gfv_chroma_key_thr_present_flag[ i ] are present and the syntax elements and gfv_chroma_key_value[ c ] and gfv_chroma_key_thr_value[ i ] might be present.gfv_chroma_key_info_present_flag equal to 0 specifies that the syntax elements gfv_chroma_key_value_present_flag[ c ], gfv_chroma_key_thr_present_flag[ i ], gfv_chroma_key_value[ c ], and gfv_chroma_key_thr_value[ i ] are not present.

[0057] gfv_chroma_key_value_present_flag[ c ] equal to 1 indicates that the syntax element gfv_chroma_key_value[ c ] is present. gfv_chroma_key_present_flag[ c ] equal to 0 indicates that the syntax element gfv_chroma_key_value[ c ] is not present.

[0058] The variable ChromaKeyDefaultValueFlag is set equal to !( gfv_chroma_key_value_present_flag

[0000] | | gfv_chroma_key_value_present_flag

[0001] | | gfv_chroma_key_value_present_flag

[0002] ).

[0059] gfv_chroma_key_value[ c ] specifies the chroma key value corresponding to the c-th colour component as follows:

[0060] – If ChromaKeyDefaultValueFlag is equal to 1, the variables GfvChromaKeyValue[ c ] are specified as follows: – GfvChromaKeyValue

[0000] is set equal to 50. – GfvChromaKeyValue

[0001] is set equal to 220. – GfvChromaKeyValue

[0002] is set equal to 100. – Otherwise, ChromaKeyDefaultValueFlag is equal to 0, the following applies: – If gfv_chroma_key_value_present_flag[ c ] is equal to 1, GfvChromaKeyValue[ c ] is set equal to the value of gfv_chroma_key_value[ c ]. – Otherwise, gfv_chroma_key_value_present_flag[ c ] is equal to 0, GfvChromaKeyValue[ c ] is not specified by this Specification.

[0061] gfv_chroma_key_thr_present_flag[ i ] equal to 1 indicates that the syntax element gfv_chroma_thr_value[ i ] is present. gfv_chroma_key_thr_present_flag[ i ] equal to 0 indicates gfv_chroma_key_thr_value[ i ] is not present.

[0062] gfv_chroma_key_thr_value[ i ], when present, specifies the i-th chroma key threshold value. When not present, the value of gfv_chroma_key_thr_value[ i ] is inferred as follows: If i is equal to 0, gfv_chroma_key_thr_value

[0000] is set equal to 48. Otherwise, i is equal to 1, gfv_chroma_key_thr_value

[0001] is set equal to 75. NOTE 3 – The syntax elements gfv_chroma_key_value_present[ c ], gfv_chroma_key_value[ c ], and gfv_chroma_key_thr_value[ i ] could be used to determine a transparency indicator for fusion of the generated face picture and background picture. For example, a transparency indicator, denoted as alpha[ x ][ y ] , for picture sample value, denoted as I[ c ][ x ][ y ] with bitDepth[ c ], where bitDepth

[0000] is equal to BitDepthY, bitDepth

[0001] and bitDepth

[0002] are equal to BitDepthC, and GfvChromaKey[ c ] values for sample coordinates x, y, and colour components c could be determined as follows: d[ x ][ y ]= 0 for( c = 0; c < 3; c++ )if( gfv_chroma_key_value_present[ c ] | | ChromaKeyDefaultValueFlag ) d[ x ][ y ] += ( I[ c ][ x ][ y ] / ( 1 << (bitDepth[ c ] − 8) ) − GfvChromaKeyValue[ c ] )2if( ( d[ x ][ y ] < gfv_chroma_key_thr_value

[0000] ) alpha[ x ][ y ] = 0 else if ( ( d[ x ][ y ] > gfv_chroma_key_thr_value

[0001] ) alpha[ x ][ y ] = 1 else alpha[ x ][ y ] = ( d[ x ][ y ] − gfv_chroma_key_thr_value

[0000] ) ÷ ( gfv_chroma_key_thr_value

[0001] − gfv_chroma_key_thr_value

[0000] ) A value of alpha[ x ][ y ] equal to 0 could indicate transparency. A value of alpha[ x ][ y ] equal to 1 could indicate opacity. Intermediate values of alpha[ x ][ y ] could indicate semitransparency.

[0063] gfv_drive_pic_fusion_flag, when present, equal to 1 indicates that the current decoded picture, which corresponds to a driving picture that may be used for fusion, may be input to GenerativeNN( ). gfv_drive_pic_fusion_flag equal to 0 indicates that the current decoded picture should not be input to GenerativeNN( ). NOTE 4 – A gfv_drive_pic_fusion_flag value of 1 can be used, for example, to indicate that the current decoded picture can be used to improve face details or handle background changes. NOTE 5 – When gfv_base_pic_flag is equal to 0 and gfv_drive_pic_fusion_flag is equal to 1, the GFV process takes three inputs: the base picture, features from keypoints and / or matrices carried in the GFV SEI message, and the current decoded picture that is a fusion picture, and outputs a picture that is generated by the GenerativeNN( ). NOTE 6 – When gfv_base_pic_flag is equal to 0 and gfv_drive_pic_fusion_flag is equal to 0, the GFV process takes twoinputs: the base picture and features from keypoints and / or matrices carried in the GFV SEI message, and outputs a picture that is generated by the GenerativeNN( ). NOTE 7 – When gfv_base_pic_flag is equal to 1, the GFV process directly outputs the cropped decoded picture.

[0064] When a GFV SEI message has gfv_base_pic_flag equal to 0 and gfv_drive_pic_fusion_flag equal to 0, the GFV SEI message pertains to the current decoded picture only.

[0065] When a GFV SEI message with a particular gfv_id value has gfv_base_pic_flag equal to 0 and gfv_drive_pic_fusion_flag equal to 1, the fusion picture for that particular gfv_id value, which is the current cropped decoded picture, remains valid for the current decoded picture and all subsequent decoded pictures of the current layer, in output order, until the end of the current CLVS or up to but excluding the decoded picture that is within the current CLVS, follows the current decoded picture in output order, and is associated with a GFV SEI message having that particular gfv_id value, whichever is earlier.

[0066] When a GFV SEI message gfvSeiA with a particular gfv_id value has gfv_cnt greater than 0 and a GFV SEI message gfvSeiB with the same gfv_id value in the same picture unit has gfv_base_pic_flag equal to 1 (i.e., the current decoded picture is a base picture), the GFV SEI message gfvSeiA shall have gfv_drive_pic_fusion_flag equal to 0.

[0067] gfv_low_confidence_face_parameter_flag equal to 1 indicates the facial parameters have been derived with low confidence. gfv_low_confidence_face_parameter_flag equal to 0 indicates the confidence information of the facial parameters is not specified.

[0068] gfv_coordinate_present_flag equal to 1 indicates that coordinate information of keypoints is present. gfv_coordinate_present_flag equal to 0 indicates that coordinate information of keypoints is not present.

[0069] It is a requirement of bitstream conformance that when gfv_matrix_type_idx[ i ] for any i from 0 to gfv_num_matrix_types_minus1 is equal to 0 or 1, the value of gfv_coordinate_present_flag shall be equal to 1.

[0070] gfv_kps_pred_flag equal to 1 indicates that the syntax elements gfv_coordinate_dx_abs[ i ] ,gfv_coordinate_dy_abs[ i ], and gfv_coordinate_dz_abs[ i ] are present and the syntax elements gfv_coordinate_dx_sign_flag[ i ], gfv_coordinate_dy_sign_flag[ i ] and gfv_coordinate_dz_sign_flag[ i ] may be present. gfv_kps_pred_flag equal to 0 indicates that the syntax elements gfv_coordinate_x_abs[ i ], gfv_coordinate_y_abs[ i ], and gfv_coordinate_z_abs[ i ] are present and the syntax elements gfv_coordinate_x_sign_flag[ i ], gfv_coordinate_y_sign_flag[ i ] and gfv_coordinate_z_sign_flag[ i ] may be present.

[0071] When gfv_coordinate_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, and gfv_kps_pred_flag is equal to 1, there shall be a previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1 in the current CLVS.

[0072] gfv_coordinate_precision_factor_minus1 plus 1 indicates the precision of key point coordinates signgalled in the SEI message. The value of gfv_coordinate_precision_factor_minus1 shall be in the range of 0 to 31, inclusive. When gfv_coordinate_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, and gfv_kps_pred_flag is equal to 1, the value of gfv_coordinate_precision_factor_minus1 is inferred to be equal to the gfv_coordinate_precision_factor_minus1 of the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0073] gfv_num_kps_minus1 plus 1 indicates the number of keypoints. The value of gfv_num_kps_minus1 shall be in the range of 0 to 210– 1, inclusive. When gfv_coordinate_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, and gfv_kps_pred_flag is equal to 1, the value of gfv_num_kps_minus1 is inferred to be equal to the gfv_num_kps_minus1 of the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0074] gfv_coordinate_z_present_flag equal to 1 indicates that z-axis coordinate information of the keypoints is present. gfv_coordinate_z_present_flag equal to 0 indicates that the z-axis coordinate information of the keypoints is not present. When gfv_coordinate_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, andgfv_kps_pred_flag is equal to 1, the value of coordinate_z_present_flag is inferred to be equal to the coordinate_z_present_flag of the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0075] gfv_coordinate_z_max_value_minus1 plus 1 indicates the maximum absolute value of z-axis coordinates of keypoints. The value of gfv_coordinate_z_max_value_minus1 shall be in the range of 0 to 216− 1, inclusive. When gfv_coordinate_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, and gfv_kps_pred_flag is equal to 1, the value of gfv_coordinate_z_max_value_minus1 is inferred to be equal to the gfv_coordinate_z_max_value_minus1, when present, in the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0076] gfv_coordinate_x_abs[ i ] is used to derive the x-axis coordinate of the i-th keypoint.

[0077] gfv_coordinate_x_sign_flag[ i ] specifies the sign of the x-axis coordinate of the i-th keypoint. When gfv_coordinate_x_sign_flag[ i ] is not present, it is inferred to be equal to 0.

[0078] gfv_coordinate_y_abs[ i ] is used to derive y-axis coordinate of i-th keypoint.

[0079] gfv_coordinate_y_sign_flag[ i ] specifies the sign of the y-axis coordinate of the i-th keypoint. When gfv_coordinate_y_sign_flag[i] is not present, it is inferred to be equal to 0.

[0080] gfv_coordinate_z_abs[ i ] is used to derive z-axis coordinate of the i-th keypoint.

[0081] gfv_coordinate_z_sign_flag[ i ] specifies the sign of the z-axis coordinate of the i-th key point. When gfv_coordinate_z_sign_flag[ i ] is not present, it is inferred to be equal to 0.

[0082] gfv_coordinate_dx_abs[ i ] specifies a difference value that is used to derive x-axis coordinate of the i-th keypoint.

[0083] gfv_coordinate_dx_sign_flag[ i ] specifies the sign of the difference value of the x-axis coordinate of the i-th keypoint. When gfv_coordinate_dx_sign_flag[ i ] is not present, it is inferred to be equal to 0.

[0084] gfv_coordinate_dy_abs[ i ] specifies a difference value that is used to derive y-axis coordinate of the i-th keypoint.

[0085] gfv_coordinate_dy_sign_flag[ i ] specifies the sign of the difference value of the y-axis coordinate of the i-th keypoint. When gfv_coordinate_yd_sign_flag[i] is not present, it is inferred to be equal to 0.

[0086] gfv_coordinate_dz_abs[ i ] specifies a difference value that is used to derive z-axis coordinate of the i-th keypoint.

[0087] gfv_coordinate_dz_sign_flag[ i ] specifies the sign of the difference value of the z-axis coordinate of the i-th key point. When gfv_coordinate_dz_sign_flag[ i ] is not present, it is inferred to be equal to 0.

[0088] If gfv_coordinate_z_max_value_minus1 is present, the variable CroppedDepth is set equal to gfv_coordinate_z_max_value_minus1 + 1. Otherwise, CroppedDepth is set equal to 0.

[0089] When gfv_kps_pred_flag is equal to 1, the variables coordinateDeltaX[ i ], coordinateDeltaY[ i ] and coordinateDeltaZ[ i ] indicating the delta x-axis coordinate, delta y-axis coordinate and delta z-axis coordinate of the i-th keypoint, respectively, are derived as follows: coordinateDeltaX[ i ] = ( 1 − 2 * gfv_coordinate_dx_sign_flag[ i ] ) * gfv_coordinate_dx_abs[ i ] ÷ ( 1 << ( gfv_coordinate_precision_factor_minus1 + 1 ) ) coordinateDeltaY * gfv_coordinate_dy_sign_flag[ i ] ) * gfv_coordinate_dy_abs[ i ] ÷ ( 1 << ( + 1 ) ) if( )2 * gfv_coordinate_dz_sign_flag[ i ] ) * gfv_coordinate_dz_abs[ i ] ÷ ( 1 << ( gfv_coordinate_precision_factor_minus1 + 1 ) )

[0090] The variables coordinateX[ i ], coordinateY[ i ], and, when gfv_coordinate_z_present_flag is equal to 1, coordinateZ[ i ] indicating the x-axis coordinate, y-axis coordinate and z-axis coordinate of the i-th keypoint, respectively, are derived as follows: If gfv_kps_pred_flag is equal to 0, the following applies: coordinateX[ i ] = ( 1 − 2 * gfv_coordinate_x_sign_flag[ i ] ) * gfv_coordinate_x_abs[ i ] ÷ ( 1 << ( gfv_coordinate_precision_factor_minus1 + 1 ) ) coordinateY[ i ] = ( 1 − 2 * gfv_coordinate_y_sign_flag[ i ] ) * gfv_coordinate_y_abs[ i ] ÷ ( 1 << ( gfv_coordinate_precision_factor_minus1 + 1 ) ) if (gfv_coordinate_z_present_flag ) coordinateZ[ i ] = ( 1 − 2 * gfv_coordinate_z_sign_flag[ i ] ) * gfv_coordinate_z_abs[ i ] ÷ ( 1 << ( gfv_coordinate_precision_factor_minus1 + 1 ) )

[0091] Otherwise (gfv_kps_pred_flag is equal to 1), the following applies: if( gfv_base_pic_flag ) { coordinateX[ i ] = (( i > 0 ) ? coordinateX[ i − 1 ] : 0 ) + coordinateDeltaX[ i ] coordinateY[ i ] = (( i > 0 ) ? coordinateY[ i − 1 ] : 0 ) + coordinateDeltaY[ i ] if (gfv_coordinate_z_present_flag ) coordinateZ[ i ] = (( i > 0 ) ? coordinateZ[ i − 1 ] : 0 ) + coordinateDeltaZ[ i ] } else if( gfv_cnt = = 0 ) { coordinateX[ i ] = BaseKpCoordinateX[ i ] + coordinateDeltaX[ i ] coordinateY[ i ] = BaseKpCoordinateY[ i ] + coordinateDeltaY[ i ] if (gfv_coordinate_z_present_flag ) coordinateZ[ i ] = BaseKpCoordinateZ[ i ] + coordinateDeltaZ[ i ] } else { coordinateX[ i ] = PrevKpCoordinateX[ i ] + coordinateDeltaX[ i ] coordinateY[ i ] = PrevKpCoordinateY[ i ] + coordinateDeltaY[ i ]coordinateZ[ i ] = PrevKpCoordinateZ[ i ] + coordinateDeltaZ[ i ] }

[0092] The following applies for derivation of the variables BaseKpCoordinateX[ i ], [ i ], BaseKpCoordinateZ[ i ], PrevKpCoordinateX[ i ], PrevKpCoordinateY[ i ], and PrevKpCoordinateZ[ i ]: if( gfv_base_pic_flag ) { PrevKpCoordinateX[ i ] = BaseKpCoordinateX[ i ] = coordinateX[ i ] PrevKpCoordinateY[ i ] = BaseKpCoordinateY[ i ] = coordinateY[ i ] if (gfv_coordinate_z_present_flag ) PrevKpCoordinateZ[ i ] = BaseKpCoordinateZ[ i ] = coordinateZ[ i ] } else { PrevKpCoordinateX[ i ] = coordinateX[ i ] PrevKpCoordinateY[ i ] = coordinateY[ i ] PrevKpCoordinateZ[ i ] = coordinateZ[ i ] }

[0093] gfv_matrix_present_flag equal to 1 indicates that matrix parameters are present. gfv_matrix_present_flag equal to 0 indicates that matrix parameters are not present. When gfv_coordinate_present_flag is equal to 0, gfv_matrix_present_flag shall be equal to 1.

[0094] gfv_matrix_pred_flag equal to 1 indicates that the syntax elements gfv_matrix_element_int[ i ][ j ][ k ][ m ] and gfv_matrix_element_dec[ i ][ j ][ k ][ m ] are present and the syntax element gfv_matrix_element_sign_flag[ i ][ j ][ k ][ m ] may be present. gfv_matrix_pred_flag equal to 0 indicates that the syntax elements gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ] and gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ] are present and the syntax element gfv_matrix_delta_element_sign_flag [ i ][ j ][ k ][ m ] may be present. When gfv_matrix_pred_flag is not present, it is inferred to be 0.

[0095] When gfv_matrix_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, and gfv_matrix_pred_flag is equal to 1, there shall be a previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1 in the current CLVS.

[0096] gfv_matrix_element_precision_factor_minus1 plus 1 indicates the precision of matrix elements signalled in the SEI message. The value of gfv_matrix_element_precision_factor_minus1 shall be in the range of 0 to 31, inclusive. When gfv_matrix_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, and gfv_matrix_pred_flag is equal to 1, the value of gfv_matrix_element_precision_factor_minus1 is inferred to be equal to the gfv_matrix_element_precision_factor_minus1 of the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0097] gfv_num_matrix_types_minus1 plus 1 indicates the number of matrix types signalled in the SEI message. The value of gfv_num_matrix_types_minus1 shall be in the range of 0 to 26− 1, inclusive. It is a requirement of bitstream conformance that when gfv_matrix_pred_flag is equal to 1 and gfv_base_pic_flag is equal to 0, the value of gfv_num_matrix_types_minus1 shall be equal to the value of gfv_num_matrix_types_minus1 in each of the preceding GFV SEI message in decoding order in the current CLVS which has the same gfv_id value as the gfv_id value in the current SEI and has gfv_base_pic_flag equal to 1. When gfv_matrix_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, and gfv_matrix_pred_flag is equal to 1, the value of gfv_matrix_type_num_minus1 is inferred to be equal to the gfv_matrix_type_num_minus1 of the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0098] gfv_matrix_type_idx[ i ] indicates the index of the i-th matrix type as specified in Table 3. The value of gfv_matrix_type_idx[ i ] shall be in the range of 0 to 63, inclusive. In bitstreams conforming to this version of this Specification, the value of gfv_matrix_type_idx[ i ] shall be in the range of 0 to 31, inclusive. Decoders conforming to this version of this Specification shall allow gfv_matrix_type_idx[ i ] to be greater than 31 to appear in the bitstream and the decoder shall ignore all information for the i-th type of matrix for which gfv_matrix_type_idx[ i ] is greater than 31. Table 1 - Specification of gfv_matrix_type_idx[ i ] Value Specification ffi l i i i h h i f * * D D ce nd ngNOTE 8 – The undefined matrxi type is used to represent the matrxi type rather than affine translation matrix, covariance matrix, rotation matrix, translation matrix and compact feature matrix. It can be used by the user to extend the matrix type.

[0099] gfv_num_matrices_equal_to_num_kps_flag[ i ] equal to 1 indicates that the number of matrices of the i-th matrix type is equal to gfv_num_kps_minus1 + 1. gfv_num_matrices_equal_to_num_kps_flag[ i ] equal to 0 indicates the number of matrices of the i-th matrix type is not equal to gfv_num_kps_minus1 + 1. If gfv_matrix_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, gfv_matrix_pred_flag is equal to 1, gfv_matrix_type_idx[ i ] is equal to 0 or 1, and gfv_coordinate_present_flag is equal to 1, the value of gfv_num_matrices_equal_to_num_kps_flag[ i ] is inferred to be equal to the gfv_num_matrices_equal_to_num_kps_flag[ i ], when present, in the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1. Otherwise, when gfv_num_matrices_equal_to_num_kps_flag[ i ] is not present, its value is inferred to be equal to 0.

[0100] gfv_num_matrices_info[ i ] provides information to derive the number of the matrices of the i-th matrix type. The value of gfv_num_matrices_info[ i ] shall be in the range of 0 to 210− 1, inclusive. When gfv_matrix_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, gfv_matrix_pred_flag is equal to 1, gfv_matrix_type_idx[ i ] is equal to 0 or 1, and either gfv_coordinate_present_flag is equal to 0 or gfv_num_matrix_equal_to_num_kps_flag[ i ] is equal to 0, the value of gfv_num_matrices_info[ i ] is inferred to be equal to the gfv_num_matrices_info[ i ], when present, in the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0101] gfv_matrix_width_minus1[ i ] plus 1 indicates the width of the matrix of the i-th matrix type. The value of gfv_matrix_width_minus1[ i ] shall be in the range of 0 to 210− 1, inclusive. When gfv_matrix_present_flag is equal to 1, gfv_matrix_pred_flag is equal to 0, gfv_matrix_pred_flag is equal to 1, and gfv_matrix_type_idx[ i ] is equal to 2 or 3 or is greater than or equal to 7, the value of gfv_matrix_width_minus1[ i ] is inferred to be equal to the gfv_matrix_width_minus1[ i ], when present, in the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0102] gfv_matrix_height_minus1[ i ] plus 1 indicates the height of the matrix of the i-th matrix type. The value of gfv_matrix_height_minus1[ i ] shall be in the range of 0 to 210− 1, inclusive. When gfv_matrix_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, gfv_matrix_pred_flag is equal to 1, and gfv_matrix_type_idx[ i ] is equal to 2 or 3 or is greater than or equal to 7, the value of gfv_matrix_height_minus1[ i ] is inferred to be equal to the gfv_matrix_height_minus1[ i ], when present, in the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0103] gfv_matrix_for_3D_space_flag[ i ] equal to 1 indicates the matrix of the i-th matrix type is a matrix defined in three-dimensional space. gfv_matrix_for_3D_space_flag[ i ] equal to 0 indicates the matrix of the i-th matrix type is a matrix defined in two-dimensional space. When gfv_matrix_present_flag is equal to 1,gfv_base_pic_flag is equal to 0, gfv_matrix_pred_flag is equal to 1, gfv_matrix_type_idx[ i ] is equal to 4, 5, or 6, and gfv_coordinate_present_flag is equal to 0, the value of gfv_matrix_for_3D_space_flag[ i ] is inferred to be equal to the gfv_matrix_for_3D_space_flag[ i ], when present, in the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0104] When gfv_matrix_width_minus1[ i ] is not present, it is inferred as follows: – If gfv_matrix_type_idx[ i ] is equal to 0, 1 or 4, and one of coordinate_z_present_flag and gfv_matrix_for_3D_space_flag[ i ] is present and equal to 1, gfv_matrix_width_minus1[i] is inferred to be equal to 2. – Otherwise, if gfv_matrix_type_idx[ i ] is equal to 0, 1 or 4, and one of coordinate_z_present_flag and gfv_matrix_for_3D_space_flag[ i ] is present and equal to 0, gfv_matrix_width_minus1[ i ] is inferred to be equal to 1. – Otherwise (gfv_matrix_type_idx[ i ] is equal to 5 or 6), gfv_matrix_width_minus1[ i ] is inferred to be equal to 0.

[0105] When gfv_matrix_height_minus1[ i ] is not present, it is inferred as follows: – If gfv_matrix_type_idx is equal to 0, 1, 4, 5 or 6, and one of gfv_coordinate_z_present_flag and gfv_matrix_for_3D_space_flag[ i ] is present and equal to 1, gfv_matrix_height_minus1[ i ] is inferred to be equal to 2. – Otherwise (gfv_matrix_type_idx is equal to 0, 1, 4, 5 or 6, and one of gfv_coordinate_z_present_flag and gfv_matrix_for_3D_space_flag[ i ] is 0), gfv_matrix_height _minus1[ i ] is inferred to be equal to 1.

[0106] The variables matrixWidth[ i ] and matrixHeight[ i ] indicating the width and height of the matrix of the i-th matrix type are derived as follows: if( gfv_matrix_pred_flag ) { matrixWidth[ i ] = BaseMatrixWidth[ i ] matrixHeight[ i ] = BaseMatrixHeight[ i ] } else { matrixWidth[ i ] = gfv_matrix_width_minus1[ i ] + 1 matrixHeight[ i ] = gfv_matrix_height_minus1[ i ] + 1 } if( gfv_base_pic_flag ) { BaseMatrixWidth[ i ] = matrixWidth[ i ] BaseMatrixHeight[ i ] = matrixHeight[ i ] }

[0107] gfv_num_matrices_minus1[ i ] plus 1 indicates the number of matrices of the i-th matrix type. The value of gfv_num_matrices_minus1[ i ] shall be in the range of 0 to 210 − 1, inclusive. When gfv_matrix_present_flag is equal to 1, gfv_base_pic_flag is equal to 0, gfv_matrix_pred_flag is equal to 1, andgfv_matrix_type_idx[ i ] is greater than or equal to 7, the value of gfv_num_matrices_minus1[ i ] is inferred to be equal to the gfv_num_matrices_minus1[ i ], when present, in the previous GFV SEI message in decoding order with the same gfv_id as the current GFV SEI message and gfv_base_pic_flag equal to 1.

[0108] The variable numMatrices[ i ] indicating the number of the matrices of the i-th matrix type is derived as follows: if( gfv_matrix_pred_flag ) numMatrices[ i ] = BaseNumMatrices[ i ] else if( gfv_matrix_type_idx[ i ] = = 0 | | gfv_matrix_type_idx[ i ] = = 1 ) { if( gfv_coordinate_present_flag ) numMatrices[ i ] = gfv_num_matrices_equal_to_num_kps_flag[ i ] ? gfv_num_kps_minus1 + 1: ( gfv_num_matrices_info[ i ] < gfv_num_kps_minus1 ? gfv_num_matrices_info [ i ] + 1: gfv_num_matrices_info [ i ] + 2 ) else numMatrices[ i ] = gfv_num_matrices_info[ i ] + 1 } else if( gfv_matrix_type_idx[ i ] >= 2 && gfv_matrix_type_idx[ i ] < 7 ) numMatrices[ i ] = 1 else numMatrices[ i ] = gfv_num_matrices_minus1[ i ] + 1 if( gfv_base_pic_flag ) BaseNumMatrices[ i ] = numMatrices[ i ]

[0109] It is a requirement of bitstream conformance that when gfv_matrix_pred_flag is equal to 1 and gfv_base_pic_flag is equal to 0, the values of numMatrices[ i ], matrixWidth[ i ], and matrixHeight[ i ] for i in the range of 0 to gfv_num_matrix_types_minus1, inclusive shall be respectively equal to the values of numMatrices[ i ], matrixWidth[ i ], and matrixHeight[ i ] for i in the range of 0 to gfv_num_matrix_types_minus1, inclusive in each of the preceding GFV SEI message in decoding order in the current CLVS which has the same gfv_id value as the gfv_id value in the current SEI and has gfv_base_pic_flag equal to 1.

[0110] gfv_matrix_element_int[ i ][ j ][ k ][ m ] indicates the integer part of the value of the matrix element at position (m, k) of the j-th matrix of the i-th matrix type. The value of gfv_matrix_element_int[ i ][ j ][ k ][ m ] shall be in the range of 0 to 232− 2, inclusive.

[0111] gfv_matrix_element_dec[ i ][ j ][ k ][ m ] indicates the decimal part of the value of the matrix element at position (m, k) of the j-th matrix of the i-th matrix type. The length of gfv_matrix_element_dec[ i ][ j ][ k ][ m ] is gfv_matrix_element_precision_factor_minus1 + 1 bits.

[0112] gfv_matrix_element_sign_flag[ i ][ j ][ k ][ m ] indicates the sign of the matrix element at position (m, k) of the j-th matrix of the i-th matrix type. When gfv_matrix_element_sign_flag[ i ][ j ][ k ][ m ]is not present, it is inferred to be equal to 0.

[0113] gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ] indicates the integer part of the difference value of the matrix element at position (m, k) of the j-th matrix of the i-th matrix type.

[0114] gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ] indicates the decimal part of the difference value of the matrix element at position (m, k) of the j-th matrix of the i-th matrix type.

[0115] gfv_matrix_delta_element_sign_flag[ i ][ j ][ k ][ m ] indicates the sign of the difference value of the matrix element at position (m, k) of the j-th matrix of the i-th matrix type. When gfv_matrix_element_sign_flag[ i ][ j ][ k ][ m ]is not present, it is inferred to be equal to 0.

[0116] When gfv_matrix_pred_flag is equal to 1, the variable matrixElementDeltaVal[ i ][ j][ k ][ m ] representing the difference value of the matrix element at position (m, k) of the j-th matrix of the i-th matrix type is derived as follows:matrixElementDeltaVal[ i][ j ][ k ][ m ] = ^1 ^ 2 ∗ gfv_matrix_delta_element_sign_flag^ i ^^ j ^^ k ^^ m ^^ ∗^^^_^ !"#$_%&'! _&'&^&(!_%&)^ # ^^ * ^^ + ^^ ^ ^ ^gfv_matrix_delta_element_int^i^^j^^k^^m^^ ,-- ^^^^_^ !"#$_&'&^&(!_."&)# / #0(_^ )!0"_^#(1 / , 2,^ ^

[0117] The variable matrixElementVal[ i ][ j][ k ][ m ] representing the value of the matrix element at position (m, k) of the j-th matrix of the i-th matrix type is derived as follows: If gfv_matrix_pred_flag is equal to 0, the following applies:matrixElementVal[ i][ j ][ k ][ m ] = ^1 ^ 2 ∗ gfv_matrix_element_sign_flag^ i ^^ j ^^ k ^^ m ^^ ∗^ ^^ ^^ ^ ^^^_^ !"#$_&'&^&(!_%&)^ # ^^ * ^^ + ^^ ^ ^ ^gfv_matrix_element_int i j k ^ m ^ ^ ,-- ^^^^_^ !"#$_&'&^&(!_."&)# / #0(_^ )!0"_^#(1 / , 2,^ ^ if( gfv_base_pic_flag ) BaseMatrixElementVal[ i][ j ][ k ][ m ] = matrixElementVal[ i][ j ][ k ][ m ] Otherwise (gfv_matrix_pred_flag is equal to 1), the following applies: if( gfv_cnt = = 0 ) matrixElementVal[ i][ j ][ k ][ m ] = BaseMatrixElementVal[ i][ j ][ k ][ m ] + matrixElementDeltaVal[ i][ j ][ k ][ m ] else matrixElementVal[ i][ j ][ k ][ m ] = PrevMatrixElementVal[ i][ j ][ k ][ m ] + matrixElementDeltaVal[ i][ j ][ k ][ m ] The following applies: if( gfv_base_pic_flag ) PrevMatrixElementVal[ i][ j ][ k ][ m ] = BaseMatrixElementVal[ i][ j ][ k ][ m ] = matrixElementVal[ i][ j ][ k ][ m ] else PrevMatrixElementVal[ i][ j ][ k ][ m ] = matrixElementVal[ i][ j ][ k ][ m ]

[0118] For a particular gfv_id value, the following process is used in increasing order of gfv_cnt to generate a video picture per each GFV SEI message that has gfv_base_pic_flag equal to 0 and a unique value of gfv_cnt within a picture unit: DeriveSigParam( ) TranslatorNN( sigKeyPoint, sigMatrix ) DeriveInputTensors( ) if( gfv_base_pic_flag = = 0 && gfv_drive_pic_fusion_flag = = 0 ) { if( ChromaFormatIdc = = 0 ) GenerativeNN( inputBaseY, inputBaseKeyPoint, inputBaseMatrix, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, CroppedDepth ) else GenerativeNN( inputBaseY, inputBaseCb, inputBaseCr, inputBaseKeyPoint, inputBaseMatrix, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, CroppedDepth ) } else if( gfv_base_pic_flag = = 0 && gfv_drive_pic_fusion_flag = = 1 ) { if( ChromaFormatIdc = = 0 ) GenerativeNN( inputBaseY, inputDriveY, inputBaseKeyPoint, inputBaseMatrix, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, CroppedDepth ) else GenerativeNN( inputBaseY, inputBaseCb, inputBaseCr, inputDriveY, inputDriveCb, inputDriveCr, inputBaseKeyPoint, inputBaseMatrix,, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, CroppedDepth ) } StoreOutputTensors( )

[0119] The process DeriveSigParam( ) for deriving the inputs of TranslatorNN( ) is specified as follows: The keypoint coordinate array sigKeyPoint and the matrix sigMatrix are derived as follows: if( gfv_coordinate_present_flag ) for( i = 0; i <= gfv_num_kps_minus1; i++ ) { sigKeyPoint[ i ]

[0000] = coordinateX[ i ] sigKeyPoint[ i ]

[0001] = coordinateY[ i ] if( gfv_coordinate_z_present_flag ) sigKeyPoint[ i ]

[0002] = coordinateZ[ i ] } else for( i = 0; i <= gfv_num_kps_minus1; i++ ) {sigKeyPoint[ i ]

[0000] = 0 sigKeyPoint[ i ]

[0001] = 0 if ( gfv_coordinate_z_present_flag ) sigKeyPoint[ i ]

[0002] = 0 } if( gfv_matrix_present_flag ) i++ )[ i ]; j++ ) for( k = 0; k < matrixHeight [ i ]; k++ ) for( l = 0;l < matrixWidth [ i ]; l++) sigMatrix[ i ][ j ][ k ][ l ] = matrixElementVal[ i ][ j][ k][ l ] else for( i = 0; i <= gfv_num_matrix_types_minus1; i++ ) for ( j = 0; j < numMatrices[ i ]; j++ ) for( k = 0; k < matrixHeight [ i ]; k++ ) for( l = 0;l < matrixWidth [ i ]; l++) sigMatrix[ i ][ j ][ k ][ l ] = 0

[0120] TranslatorNN( ) is a process to translate the various formats of the facial parameters carried in the SEI message to the fixed format of the facial parameters to be input to the generative network to generate the output picture.

[0121] Inputs to TranslatorNN( ) are: – sigKeyPoint and sigMatrix

[0122] Outputs of TranslatorNN( ) are: – convKeyPoint and convNumKeyPoint – convMatrix and convNumMatrix, convMatrixWidth, convMatrixHeight

[0123] The process DeriveInputTensors( ) for deriving the inputs of GenerativeNN( ) is specified as follows:

[0124] When gfv_base_pic_flag is equal to 1, the BasePicture input tensor inputBaseY, inputBaseCb and inputBaseCr are derived as follows: for( x = 0; x < CroppedWidth; x++ ) for ( y = 0; y < CroppedHeight; y++ ) inputBaseY[ x ][ y ] = InpY( baseCroppedYPic[ x ][ y ] ) if( ChromaFormatIdc != 0 ) for( x = 0; x < CroppedWidth / SubWidthC; x++ ) for ( y = 0; y < CroppedHeight / SubHeightC; y++ ) { inputBaseCb[ x][ y ] = InpC( baseCroppedCbPic[ x][ y ] )inputBaseCr[ x][ y ] = InpC( baseCroppedCrPic[ x ][ y ] ) }

[0125] When gfv_base_pic_flag is equal to 0 and gfv_drive_pic_fusion_flag is equal to 1, the DrivePicture luma sample array inputDriveY, inputDriveCb and input DriveCr are derived as follows: for( x = 0; x< CroppedWidth; x++ ) for ( y = 0; y< CroppedHeight; y++ ) inputDriveY[ x ][ y ] = InpY( driveCroppedYPic[ x ][ y ] ) if( ChromaFormatIdc != 0 ) for( x = 0; x< CroppedWidth / SubWidthC; x++ ) for( y = 0; y < CroppedHeight / SubHeightC; y++ ) { InputDriveCb[ x][ y ] = InpC( driveCroppedCbPic[ x][ y ] ) InputDriveCr[ x][ y ] = InpC( driveCroppedCrPic[ x ][ y ] ) }

[0126] When gfv_base_pic_flag is equal to 0, the keypoint coordinate array inputDriveKeyPoint and the matrix inputDriveMatrix for the current picture are derived as follows: for( i = 0; i < = convNumKeyPoint; i++ ) { inputDriveKeyPoint[ i ]

[0000] = convKeyPoint[ i ]

[0000] inputDriveKeyPoint [ i ]

[0001] = convKeyPoint[ i ]

[0001] inputDriveKeyPoint [ i ]

[0002] = convKeyPoint[ i ]

[0002] } for( j = 0; j < convNumMatrix; j++ ) for( k = 0; k < convMatrixHeight; k++ ) for( m = 0; m < convMatrixWidth; m++ ) inputDriveMatrix[ j ][ k ][ m ] = convMatrix [ j ][ k ][ m ]

[0127] When gfv_base_pic_flag is equal to 1, the keypoint coordinate array inputBaseKeyPoint and the matrix inputBaseMatrix for the base picture are derived as follows: for( i = 0; i <= convNumKeyPoint; i++ ) { inputBaseKeyPoint[ i ]

[0000] = convKeyPoint[ i ]

[0000] inputBaseKeyPoint [ i ]

[0001] = convKeyPoint[ i ]

[0001] inputBaseKeyPoint [ i ]

[0002] = convKeyPoint[ i ]

[0002] } for( j = 0; j < convNumMatrix; j++ ) for( k = 0; k < convMatrixHeight; k++ ) for( l = 0; l < convMatrixWidth; l++ ) inputBaseMatrix[ j ][ k ][ l ] = convMatrix [ j ][ k ][ l ]

[0128] Where the functions InpY( ) and InpC( ) are specified as follows: InpY( x ) = x ÷ ( ( 1 << BitDepthY) − 1 ) InpC( x ) = x ÷ ( ( 1 << BitDepthC) − 1 ) ( ) is a process to generate the sample values of an output picture corresponding to awhen gfc_base_pic_flag is equal to 0. Input values to GenerativeNN( ) and output values from GenerativeNN( ) are real numbers.

[0130] Inputs to GenerativeNN( ) are: – When gfv_base_pic_flag is equal to 0, gfv_drive_pic_fusion_flag is equal to 0, and ChromaFormatIdc is equal to 0: inputBaseY, inputBaseKeyPoint, inputBaseMatrix, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight,and CroppedDepth. – When gfv_base_pic_flag is equal to 0, gfv_drive_pic_fusion_flag is equal to 0, and ChromaFormatIdc is not equal to 0: inputBaseY, inputBaseCb, inputBaseCr, inputBaseKeyPoint, inputBaseMatrix, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, and CroppedDepth. – When gfv_base_pic_flag is equal to 0, gfv_drive_pic_fusion_flag is equal to 1, gfv_chroma_key_info_present_flag is equal to 0, and ChromaFormatIdc is equal to 0: inputBaseY, inputDriveY, inputBaseKeyPoint, inputBaseMatrix, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, and CroppedDepth. – When gfv_base_pic_flag is equal to 0, gfv_drive_pic_fusion_flag is equal to 1, gfv_chroma_key_info_present_flag is equal to 0, and ChromaFormatIdc is not equal to 0: inputBaseY, inputBaseCb, inputBaseCr, inputDriveY, inputDriveCb, inputDriveCr , inputBaseKeyPoint, inputBaseMatrix,, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, and CroppedDepth. – When gfv_base_pic_flag is equal to 0, gfv_drive_pic_fusion_flag is equal to 1, gfv_chroma_key_info_present_flag is equal to 1, and ChromaFormatIdc is equal to 0: inputBaseY, inputDriveY, inputBaseKeyPoint, inputBaseMatrix, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, CroppedDepth, gfv_chroma_key_thr_value

[0000] , gfv_chroma_key_thr_value

[0001] , and GfvChromaKeyValue

[0000] . – When gfv_base_pic_flag is equal to 0, gfv_drive_pic_fusion_flag is equal to 1, gfv_chroma_key_info_present_flag is equal to 0, and ChromaFormatIdc is not equal to 0: inputBaseY, inputBaseCb, inputBaseCr, inputDriveY, inputDriveCb, inputDriveCr , inputBaseKeyPoint, inputBaseMatrix, inputDriveKeyPoint, inputDriveMatrix, CroppedWidth, CroppedHeight, CroppedDepth, gfv_chroma_key_thr_value

[0000] , gfv_chroma_key_thr_value

[0001] , and, when specified, GfvChromaKeyValue

[0000] , GfvChromaKeyValue

[0001] , and GfvChromaKeyValue

[0002] .

[0131] Outputs of GenerativeNN( ) are: – A luma sample array genY– When ChromaFormatIdc is not equal to 0, two chroma sample arrays genCb and genCr.

[0132] The process StoreOutputTensors( ) for deriving the output is specified as follows: When gfv_base_pic_flag is equal to 0, the output sample array outYPic[ x ][ y ], outCbPic[ x ][ y ], and outCrPic[ x ][ y ] are derived as follows: for( x = 0; x < CroppedWidth; x++ ) for( y = 0; y < CroppedHeight; y++ ) outputYPic[ x ][ y ] = OutY( genY[ x ][ y ] ) if( ChromaFormatIdc != 0 ) for( x = 0; x < CroppedWidth / SubWidthC; x++ ) for( y = 0; y < CroppedHeight / SubHeightC; y++ ) { outputCbPic[ x ][ y ] = OutC( genCb[ x ][ y ] ) outputCrPic[ x][ y ] = OutC( genCr[ x ][ y ] ) } When gfv_base_pic_flag is equal to 1, the output sample array outYPic[ x ][ y ], outCbPic[ x ][ y ], and outCrPic[ x ][ y ] are derived as follows (each output picture derived by the process StoreOutputTensors( ) is referred to as a GFV-generated picture): for( x = 0; x< CroppedWidth; x++ ) for( y = 0; y< CroppedHeight; y++ ) outputYPic[ x ][ y ] = baseCroppedYPic[ x ][ y ] if( ChromaFormatIdc != 0 ) for( x = 0; x< CroppedWidth / SubWidthC; x++ ) for( y = 0; y< CroppedHeight / SubHeightC; y++ ) { outputCbPic[ x ][ y ] = baseCroppedCbPic[ x ][ y ] outputCrPic[ x][ y ] = baseCroppedCbPic[ x ][ y ] } Where the functions OutY( ) and OutC( ) are specified as follows: OutY( x ) = Clip3( 0, ( 1 << BitDepthY ) − 1 , x * ( ( 1 << BitDepthY ) − 1 ) OutC( x ) = Clip3( 0, ( 1 << BitDepthC ) − 1 , x * ( ( 1 << BitDepthC ) − 1 )

[0133] The output order of GFV-generated pictures corresponding to the GFV SEI messages in a picture unit with the same gfv_id value and different gfv_cnt values shall be in increasing order of the gfv_cnt values. For any two pictures picA and picB wherein picA precedes picB in output order, any GFV-generated picture corresponding to a GFV SEI message with a particular gfv_id value and associated with picA shall precede, in output order, any GFV-generated picture corresponding to a GFV SEI message with the particular gfv_id value and associated with picB. 4. Technical problems solved by disclosed technical solutions

[0134] The current design of the GFV SEI message has the following problems.

[0135] First, when GFV SEI messages are present in a CLVS of a coded video bitstream, if the CLVS is decoded by a decoding system that does not support processing of GFV SEI messages, the resulting output pictures would typically be of very low picture rate, e.g., there may be only one output picture that is the cropped decoded picture of the first picture of the CLVS in decoding order. The content provider may want to make sure that such a CLVS or such a bitstream is only consumed by decoding systems that do support processing of GFV SEI messages. However, there lacks such an indication for content providers to express or impose such an intent.

[0136] Second, the value ranges for a number of ue(v)-coded syntax elements are missing, including gfv_chroma_key_thr_value[ i ], gfv_coordinate_x_abs[ i ], gfv_coordinate_y_abs[ i ], gfv_coordinate_z_abs[ i ], gfv_coordinate_dx_abs[ i ], gfv_coordinate_dy_abs[ i ], gfv_coordinate_dz_abs[ i ], gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ], and gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ]. 5. A listing of solutions and embodiments

[0137] 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. For any of the items below, the phrase “decoded picture” can also be replaced with the phrase “cropped decoded picture.” 1) To solve problem 1, in one example, an indication may be included in a coded video bitstream, a CVS, or a CLVS to indicate that there may be GFV SEI messages present in the coded video bitstream, the CVS, or the CLVS. a. In one example, furthermore, the indication may further indicate that decoding systems that do not support processing of GFV SEI messages shall ignore the coded video bitstream, the CVS, or the CLVS. b. In one example, furthermore, the indication may further indicate that decoding systems that do not support processing of GFV SEI messages should ignore the coded video bitstream, the CVS, or the CLVS. c. In one example, furthermore, the indication may be included in one or more of the sequence parameter set (SPS) and the video parameter set (VPS) and may indicate that there may be GFV SEI messages present in the CLVSs or CVSs to which the SPS or VPS applies. d. In one example, furthermore, the indication may be included in a syntax structure that contains information on profile and level. e. In one example, for H.264 / AVC, the indication may be specified using a currently reserved bit between the profile_idc syntax elements and the level_idc syntax element in the SPS. f. In one example, for H.265 / HEVC, the indication may be specified using a currently reserved bit in the profile_tier_level( ) syntax structure.g. In one example, for H.265 / HEVC, the indication may be specified through modifying the semantics of the general_non_packed_constraint_flag, e.g., to be as follows: general_non_packed_constraint_flag equal to 1 specifies that there are no frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, cubemap projection SEI messages, or GFV SEI messages present in the CVS. general_non_packed_constraint_flag equal to 0 indicates that there may or may not be one or more frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, cubemap projection SEI messages, or GFV SEI messages present in the CVS. h. In one example, for H.266 / VVC, the indication may be specified using a currently reserved bit in the general_constraints_info( ) syntax structure. i. In one example, for H.266 / VVC, the indication may be specified through adding a bit to the vui_parameters( ) syntax structure specified in VSEI. j. In one example, for H.266 / VVC, the indication may be specified through modifying the semantics of the vui_non_packed_constraint_flag that is included in the vui_parameters( ) syntax structure specified in VSEI, e.g., to be as follows: vui_non_packed_constraint_flag equal to 1 specifies that there shall not be any frame packing arrangement SEI messages or GFV SEI messages present in the bitstream that apply to the CLVS. vui_non_packed_constraint_flag equal to 0 does not impose such a constraint. k. In one example, the indication may be specified through use of the SEI manifest SEI message, e.g., by setting manifest_sei_payload_type[ i ] for a value of i to be equal to the SEI payloadType value of the GFV SEI message. i. In one example, the indication may be further specified through setting manifest_sei_description[ i ] for the value of i to be equal to 1. ) To solve problem 2, in one example, it is specified that, the value of gfv_chroma_key_thr_value[ i ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 255. ) To solve problem 2, in one example, it is specified that, the value of gfv_coordinate_x_abs[ i ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 216− 1. b. In one example, N is equal to 232− 2. ) To solve problem 2, in one example, it is specified that, the value of gfv_coordinate_y_abs[ i ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 216− 1. b. In one example, N is equal to 232 − 2.5) To solve problem 2, in one example, it is specified that, the value of gfv_coordinate_z_abs[ i ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 216− 1. b. In one example, N is equal to 232− 2. 6) To solve problem 2, in one example, it is specified that, the value of gfv_coordinate_dx_abs[ i ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 216− 1. b. In one example, N is equal to 232− 2. 7) To solve problem 2, in one example, it is specified that, the value of gfv_coordinate_dy_abs[ i ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 216− 1. b. In one example, N is equal to 232− 2. 8) To solve problem 2, in one example, it is specified that, the value of gfv_coordinate_dz_abs[ i ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 216− 1. b. In one example, N is equal to 232− 2. 9) To solve problem 2, in one example, it is specified that, the value of gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 232− 2. b. In one example, N is equal to 216− 1. 10) To solve problem 2, in one example, it is specified that, the value of gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0. a. In one example, N is equal to 232− 2. b. In one example, N is equal to 216− 1. 6. References [1] ITU-T and ISO / IEC, “High efficiency video coding”, 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. [4] S. McCarthy, J. Chen, S. Deshpande, M. M. Hannuksela, Hendry (eds), “Technologies under consideration for future extensions of VSEI (version 5),” JVET output document JVET-AI2032-v2, publicly available online herein: https: / / www.jvet-experts.org / doc_end_user / documents / 35_Sapporo / wg11 / JVET-AI2032-v2.zip.

[0138] 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 wireless fidelity (Wi-Fi) or cellular interfaces.

[0139] 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.

[0140] 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.

[0141] 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 (IoT) receiver, and so on. The apparatus 4100 may include one or more processors 4102, one or more memories 4104 and video processing circuitry 4106. The processor(s) 4102 may be configured to implement one or more methods described in the present 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.

[0142] FIG.4 is a flowchart for an example method 4200 of video processing. The method 4200 determines that an indication is included a coded video bitstream, a coded video sequence (CVS), or a coded layer videosequence (CLVS) to indicate that there are generative face video (GFV) supplemental enhancement information (SEI) messages present in the coded video bitstream, the CVS, or the CLVS at step 4202. A conversion is performed between a visual media data and a bitstream based on the indication at step 4204. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

[0143] 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.

[0144] 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.

[0145] Source device 4310 may include a video source 4312, a video encoder 4314, and an input / output (I / O) interface 4316. Video source 4312 may include a source such as a video capture device, an interface to receive video data from a video content provider, and / or a computer graphics system for generating video data, or a combination of such sources. The video data may comprise one or more pictures. Video encoder 4314 encodes the video data from video source 4312 to generate a bitstream. The bitstream may include a sequence of bits that form a coded representation of the video data. The bitstream may include coded pictures and associated data. The coded picture is a coded representation of a picture. The associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. I / O interface 4316 may include a modulator / demodulator (modem) and / or a transmitter. The encoded video data may be transmitted directly to destination device 4320 via I / O interface 4316 through network 4330. The encoded video data may also be stored onto a storage medium / server 4340 for access by destination device 4320.

[0146] 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.

[0147] Video encoder 4314 and video decoder 4324 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, Versatile Video Coding (VVC) standard and other current and / or further standards.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] Furthermore, some components, such as motion estimation unit 4404 and motion compensation unit 4405 may be highly integrated, but are represented in the example of video encoder 4400 separately for purposes of explanation.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] In another example, motion estimation unit 4404 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD). The motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 4500 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] Transform processing unit 4408 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.

[0166] After transform processing unit 4408 generates a transform coefficient video block associated with the current video block, quantization unit 4409 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.

[0167] 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.

[0168] After reconstruction unit 4412 reconstructs the video block, the loop filtering operation may be performed to reduce video blocking artifacts in the video block.

[0169] 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.

[0170] FIG.7 is a block diagram illustrating an example of video decoder 4500 which may be video decoder 4324 in the system 4300 illustrated in FIG.5. The video decoder 4500 may be configured to perform any or all of the techniques 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 videodecoder 4500. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

[0171] 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.

[0172] 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.

[0173] Motion compensation unit 4502 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.

[0174] 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.

[0175] 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.

[0176] Intra prediction unit 4503 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit 4504 inverse quantizes, i.e., de- quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 4501. Inverse transform unit 4505 applies an inverse transform.

[0177] Reconstruction unit 4506 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 4502 or intra prediction unit 4503 to form decoded blocks. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts. The decoded video blocks are then stored in buffer 4507, which provides reference blocks for subsequent motion compensation / intra prediction and also produces decoded video for presentation on a display device.

[0178] FIG. 8 is a schematic diagram of an example encoder 4600. The encoder 4600 is suitable for implementing the techniques of VVC. The encoder 4600 includes three in-loop filters, namely a deblocking filter(DF) 4602, a sample adaptive offset (SAO) 4604, and an adaptive loop filter (ALF) 4606. Unlike the DF 4602, which uses predefined filters, the SAO 4604 and the ALF 4606 utilize the original samples of the current picture to reduce the mean square errors between the original samples and the reconstructed samples by adding an offset and by applying a finite impulse response (FIR) filter, respectively, with coded side information signaling the offsets and filter coefficients. The ALF 4606 is located at the last processing stage of each picture and can be regarded as a tool trying to catch and fix artifacts created by the previous stages.

[0179] 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.

[0180] FIG. 9 is a flowchart for another example method 4700 of video processing. The method 4700 determines that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255 at step 4702. A conversion between a visual media data and a bitstream is performed based on the gfv_chroma_key_thr_value[ i ] at step 4704. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

[0181] 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.

[0182] A listing of solutions preferred by some examples is provided next.

[0183] The following solutions show examples of techniques discussed herein.

[0184] 1. A method for processing media data comprising: determining that an indication is included a coded video bitstream, a coded video sequence (CVS), or a coded layer video sequence (CLVS) to indicate thatthere are generative face video (GFV) supplemental enhancement information (SEI) messages present in the coded video bitstream, the CVS, or the CLVS; and performing a conversion between a visual media data and a bitstream based on the indication.

[0185] 2. The method of claim 1, wherein the indication may further indicate that decoding systems that do not support processing of the GFV SEI messages shall ignore the coded video bitstream, the CVS, or the CLVS.

[0186] 3. The method of any of claims 1-2, wherein the indication may further indicate that decoding systems that do not support processing of the GFV SEI messages should ignore the coded video bitstream, the CVS, or the CLVS.

[0187] 4. The method of any of claims 1-3, wherein the indication is included in one or more of a sequence parameter set (SPS) and a video parameter set (VPS) and indicates that there are GFV SEI messages present in the CLVSs or the CVSs to which the SPS or the VPS applies.

[0188] 5. The method of any of claims 1-4, wherein the indication may be included in a syntax structure that contains information on profile and level.

[0189] 6. The method of any of claims 1-5, wherein the indication is specified using a currently reserved bit between profile_idc syntax elements and level_idc syntax element in the SPS.

[0190] 7. The method of any of claims 1-6, wherein for H.265 / HEVC, the indication is specified using a currently reserved bit in a profile_tier_level( ) syntax structure.

[0191] 8. The method of any of claims 1-7, wherein for a H.265 / high efficiency video coding (HEVC) standard, the indication is specified through modifying semantics of a general_non_packed_constraint_flag to be one or more of the following: general_non_packed_constraint_flag equal to 1 specifies that there are no frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, cubemap projection SEI messages, or GFV SEI messages present in the CVS, and general_non_packed_constraint_flag equal to 0 indicates that there may or may not be one or more frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, cubemap projection SEI messages, or GFV SEI messages present in the CVS.

[0192] 9. The method of any of claims 1-8, wherein for a H.266 / versatile video coding (VVC) standard, the indication is specified using a currently reserved bit in a general_constraints_info( ) syntax structure.

[0193] 10. The method of any of claims 1-9, wherein for a H.266 / versatile video coding (VVC) standard, the indication may be specified through adding a bit to the vui_parameters( ) syntax structure specified in a versatile SEI (VSEI) message.

[0194] 11. The method of any of claims 1-10, wherein wherein for a H.266 / versatile video coding (VVC) standard, the indication is specified through modifying the semantics of a vui_non_packed_constraint_flagincluded in a vui_parameters( ) syntax structure specified in a versatile SEI (VSEI) message to be one or more of the following: vui_non_packed_constraint_flag equal to 1 specifies that there shall not be any frame packing arrangement SEI messages or GFV SEI messages present in the bitstream that applies to the CLVS; and vui_non_packed_constraint_flag equal to 0 does not impose such a constraint.

[0195] 12. The method of any of claims 1-11, wherein the indication is specified through use of an SEI manifest SEI message by setting manifest_sei_payload_type[ i ] for a value of i to be equal to an SEI payloadType value of the GFV SEI message.

[0196] 13. The method of any of claims 1-12, wherein the indication is further specified through setting manifest_sei_description[ i ] for a value of i to be equal to 1.

[0197] 14. The method of any of claims 1-13, wherein the value of gfv_chroma_key_thr_value[ i ] shall be in the range of 0 to N, inclusive, where N is an integer greater than 0.

[0198] 15. The method of any of claims 1-14, wherein N is equal to 255.

[0199] 16. The method of any of claims 1-15, wherein a value of gfv_coordinate_x_abs[ i ] is in a range of 0 to N, inclusive, where N is an integer greater than 0.

[0200] 17. The method of any of claims 1-16, wherein a value of gfv_coordinate_y_abs[ i ] is in a range of 0 to N, inclusive, where N is an integer greater than 0.

[0201] 18. The method of any of claims 1-17, wherein a value of gfv_coordinate_z_abs[ i ] is in a range of 0 to N, inclusive, where N is an integer greater than 0.

[0202] 19. The method of any of claims 1-18, wherein a value of gfv_coordinate_dx_abs[ i ] is in a range of 0 to N, inclusive, where N is an integer greater than 0.

[0203] 20. The method of any of claims 1-19, wherein a value of gfv_coordinate_dy_abs[ i ] is in a range of 0 to N, inclusive, where N is an integer greater than 0.

[0204] 21. The method of any of claims 1-20, wherein a value of gfv_coordinate_dz_abs[ i ] is in a range of 0 to N, inclusive, where N is an integer greater than 0.

[0205] 22. The method of any of claims 1-21, wherein a value of gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ] is in a range of 0 to N, inclusive, where N is an integer greater than 0.

[0206] 23. The method of any of claims 1-22, wherein a value of gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ] is in a range of 0 to N, inclusive, where N is an integer greater than 0.

[0207] 24. The method of any of claims 16-23, wherein N is equal to 216– 1, or wherein N is equal to 232− 2.

[0208] 25. The method of any of claims 1-24, wherein the conversion includes encoding the video into the bitstream.

[0209] 26. The method of any of claims 1-24, wherein the conversion includes decoding the video from the bitstream.

[0210] 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 claims 1-26.

[0211] 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 claims 1-26.

[0212] 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 that an indication is included a coded video bitstream, a coded video sequence (CVS), or a coded layer video sequence (CLVS) to indicate that there are generative face video (GFV) supplemental enhancement information (SEI) messages present in the coded video bitstream, the CVS, or the CLVS; and generating a bitstream based on the the indication.

[0213] 30. A method for storing bitstream of a video comprising: determining that an indication is included a coded video bitstream, a coded video sequence (CVS), or a coded layer video sequence (CLVS) to indicate that there are generative face video (GFV) supplemental enhancement information (SEI) messages present in the coded video bitstream, the CVS, or the CLVS; generating a bitstream based on the indication; and storing the bitstream in a non-transitory computer-readable recording medium.

[0214] 31. A method, apparatus, or system described in the present disclosure.

[0215] The following solutions show further examples of techniques discussed herein.

[0216] 1. A method for processing media data comprising: determining that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; and performing a conversion between a visual media data and a bitstream based on the gfv_chroma_key_thr_value[ i ].

[0217] 2. The method of solution 1, wherein the GFV SEI further comprises an ith GFV coordinate x absolute value (gfv_coordinate_x_abs[ i ]) where a value of the gfv_coordinate_x_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

[0218] 3. The method of any of solutions 1-2, wherein the GFV SEI further comprises an ith GFV coordinate y absolute value (gfv_coordinate_y_abs[ i ]) where a value of the gfv_coordinate_y_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

[0219] 4. The method of any of solutions 1-3, wherein the GFV SEI further comprises an ith GFV coordinate z absolute value (gfv_coordinate_z_abs[ i ]) where a value of the gfv_coordinate_z_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

[0220] 5. The method of any of solutions 1-4, wherein the GFV SEI further comprises an ith GFV coordinate difference x axis absolute value (gfv_coordinate_dx_abs[ i ]) where a value of the gfv_coordinate_dx_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

[0221] 6. The method of any of solutions 1-5, wherein the GFV SEI further comprises an ith GFV coordinate difference y axis absolute value (gfv_coordinate_dy_abs[ i ]) where a value of the gfv_coordinate_dy_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

[0222] 7. The method of any of solutions 1-6, wherein the GFV SEI further comprises an ith GFV coordinate difference z axis absolute value (gfv_coordinate_dz_abs[ i ]) where a value of the gfv_coordinate_dz_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

[0223] 8. The method of any of solutions 1-7, wherein the GFV SEI further comprises a GFV matrix integer portion difference value of a matrix element at position (m, k) of a j-th matrix of an i-th matrix type (gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ]) where a value of the gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ] shall be in a range of zero to 232 − 2, inclusive.

[0224] 9. The method of any of solutions 1-8, wherein the GFV SEI further comprises a GFV matrix decimal portion difference value of a matrix element at position (m, k) of a j-th matrix of an i-th matrix type (gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ]) where a value of the gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ] shall be in a range of zero to an integer greater than zero, inclusive.

[0225] 10. The method of any of solutions 1-9, wherein the integer greater than zero is equal to 216– 1.

[0226] 11. The method of any of solutions 1-9, wherein the integer greater than zero is equal to 232− 2.

[0227] 12. The method of any of solutions 1-11, wherein an indication is included in the bitstream, a coded video sequence (CVS), or a coded layer video sequence (CLVS) to indicate the GFV SEI message is present in the bitstream, the CVS, or the CLVS.

[0228] 13. The method of any of solutions 1-12, wherein the indication further indicates that decoding systems that do not support processing of the GFV SEI messages shall ignore the coded video bitstream, the CVS, or the CLVS.

[0229] 14. The method of any of solutions 1-13, wherein the indication further indicates that decoding systems that do not support processing of the GFV SEI messages should ignore the coded video bitstream, the CVS, or the CLVS.

[0230] 15. The method of any of solutions 1-14, wherein the indication is included in one or more of a sequence parameter set (SPS) and a video parameter set (VPS) and indicates that there are GFV SEI messages present in a CLVS or a CVS to which the SPS or the VPS applies.

[0231] 16. The method of any of solutions 1-15, wherein the indication is included in a syntax structure that contains information on profile and level.

[0232] 17. The method of any of solutions 1-16, wherein the indication is specified using a reserved bit between profile identification code (profile_idc) syntax elements and level identification code (level_idc) syntax element in an SPS.

[0233] 18. The method of any of solutions 1-17, wherein the indication is specified using a reserved bit in a profile tier level (profile_tier_level( )) syntax structure.

[0234] 19. The method of any of solutions 1-18, wherein the indication is specified in semantics of a general non-packed constraint flag (general_non_packed_constraint_flag) which include one or more of the following: general_non_packed_constraint_flag equal to 1 specifies that there are no frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, cubemap projection SEI messages, or GFV SEI messages present in the CVS; or general_non_packed_constraint_flag equal to 0 indicates that there may or may not be one or more frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, cubemap projection SEI messages, or GFV SEI messages present in the CVS.

[0235] 20. The method of any of solutions 1-19, wherein the indication is specified using a reserved bit in a general constraints information (general_constraints_info( )) syntax structure.

[0236] 21. The method of any of solutions 1-20, wherein the indication is specified using a bit in a video usability information (VUI) parameters (vui_parameters( )) syntax structure specified in a versatile SEI (VSEI) message.

[0237] 22. The method of any of solutions 1-21, wherein the indication is specified in semantics of a VUI non packed constraint flag (vui_non_packed_constraint_flag) included in a vui_parameters( ) syntax structure specified in a versatile SEI (VSEI) message, and wherein the semantics include one or more of the following: vui_non_packed_constraint_flag equal to 1 specifies that there shall not be any frame packing arrangement SEI messages or GFV SEI messages present in the bitstream that applies to the CLVS; and vui_non_packed_constraint_flag equal to 0 does not impose such a constraint.

[0238] 23. The method of any of solutions 1-22, wherein the indication is specified in an SEI manifest SEI message, and wherein the indication includes setting a manifest SEI payload type for a value of i (manifest_sei_payload_type[ i ]) to be equal to an SEI payloadType value of the GFV SEI message.

[0239] 24. The method of any of solutions 1-23, wherein the indication is further specified by setting for a manifest SEI description value of i (manifest_sei_description[ i ]) to be equal to one.

[0240] 25. The method of any of solutions 1-24, wherein the conversion includes encoding the video into the bitstream.

[0241] 26. The method of any of solutions 1-24, wherein the conversion includes decoding the video from the bitstream.

[0242] 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.

[0243] 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.

[0244] 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 that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; and generating a bitstream based on the the indication.

[0245] 30. A method for storing bitstream of a video comprising: determining that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; generating a bitstream based on the indication; and storing the bitstream in a non-transitory computer-readable recording medium.

[0246] In the solutions described herein, an encoder may conform to the format rule by producing a coded representation according to the format rule. In the solutions described herein, a decoder may use the format rule to parse syntax elements in the coded representation with the knowledge of presence and absence of syntax elements according to the format rule to produce decoded video.

[0247] 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.

[0248] 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 computerprogram products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine- generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.

[0249] 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.

[0250] 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., a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

[0251] 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.

[0252] 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.

[0253] 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.

[0254] 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.

[0255] A first component is directly coupled to a second component when there are no intervening components, except for a line, a trace, or another medium between the first component and the second component. The first component is indirectly coupled to the second component when there are intervening components other than a line, a trace, or another medium between the first component and the second component. The term “coupled” and its variants include both directly coupled and indirectly coupled. The use of the term “about” means a range including ±10% of the subsequent number unless otherwise stated.

[0256] 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.

[0257] In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled may be directly connected or may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions,and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

CLAIMS What is claimed is:

1. A method for processing media data comprising: determining that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; and performing a conversion between a visual media data and a bitstream based on the gfv_chroma_key_thr_value[ i ].

2. The method of claim 1, wherein the GFV SEI further comprises an ith GFV coordinate x absolute value (gfv_coordinate_x_abs[ i ]) where a value of the gfv_coordinate_x_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

3. The method of any of claims 1-2, wherein the GFV SEI further comprises an ith GFV coordinate y absolute value (gfv_coordinate_y_abs[ i ]) where a value of the gfv_coordinate_y_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

4. The method of any of claims 1-3, wherein the GFV SEI further comprises an ith GFV coordinate z absolute value (gfv_coordinate_z_abs[ i ]) where a value of the gfv_coordinate_z_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

5. The method of any of claims 1-4, wherein the GFV SEI further comprises an ith GFV coordinate difference x axis absolute value (gfv_coordinate_dx_abs[ i ]) where a value of the gfv_coordinate_dx_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

6. The method of any of claims 1-5, wherein the GFV SEI further comprises an ith GFV coordinate difference y axis absolute value (gfv_coordinate_dy_abs[ i ]) where a value of the gfv_coordinate_dy_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

7. The method of any of claims 1-6, wherein the GFV SEI further comprises an ith GFV coordinate difference z axis absolute value (gfv_coordinate_dz_abs[ i ]) where a value of the gfv_coordinate_dz_abs[ i ] shall be in a range of zero to an integer greater than zero, inclusive.

8. The method of any of claims 1-7, wherein the GFV SEI further comprises a GFV matrix integer portion difference value of a matrix element at position (m, k) of a j-th matrix of an i-th matrix type(gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ]) where a value of the gfv_matrix_delta_element_int[ i ][ j ][ k ][ m ] shall be in a range of zero to 232− 2, inclusive.

9. The method of any of claims 1-8, wherein the GFV SEI further comprises a GFV matrix decimal portion difference value of a matrix element at position (m, k) of a j-th matrix of an i-th matrix type (gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ]) where a value of the gfv_matrix_delta_element_dec[ i ][ j ][ k ][ m ] shall be in a range of zero to an integer greater than zero, inclusive.

10. The method of any of claims 1-9, wherein the integer greater than zero is equal to 216– 1.

11. The method of any of claims 1-9, wherein the integer greater than zero is equal to 232− 2.

12. The method of any of claims 1-11, wherein an indication is included in the bitstream, a coded video sequence (CVS), or a coded layer video sequence (CLVS) to indicate the GFV SEI message is present in the bitstream, the CVS, or the CLVS.

13. The method of any of claims 1-12, wherein the indication further indicates that decoding systems that do not support processing of the GFV SEI messages shall ignore the coded video bitstream, the CVS, or the CLVS.

14. The method of any of claims 1-13, wherein the indication further indicates that decoding systems that do not support processing of the GFV SEI messages should ignore the coded video bitstream, the CVS, or the CLVS.

15. The method of any of claims 1-14, wherein the indication is included in one or more of a sequence parameter set (SPS) and a video parameter set (VPS) and indicates that there are GFV SEI messages present in a CLVS or a CVS to which the SPS or the VPS applies.

16. The method of any of claims 1-15, wherein the indication is included in a syntax structure that contains information on profile and level.

17. The method of any of claims 1-16, wherein the indication is specified using a reserved bit between profile identification code (profile_idc) syntax elements and level identification code (level_idc) syntax element in an SPS.

18. The method of any of claims 1-17, wherein the indication is specified using a reserved bit in a profile tier level (profile_tier_level( )) syntax structure.

19. The method of any of claims 1-18, wherein the indication is specified in semantics of a general non- packed constraint flag (general_non_packed_constraint_flag) which include one or more of the following: general_non_packed_constraint_flag equal to 1 specifies that there are no frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, cubemap projection SEI messages, or GFV SEI messages present in the CVS; or general_non_packed_constraint_flag equal to 0 indicates that there may or may not be one or more frame packing arrangement SEI messages, segmented rectangular frame packing arrangement SEI messages, equirectangular projection SEI messages, cubemap projection SEI messages, or GFV SEI messages present in the CVS.

20. The method of any of claims 1-19, wherein the indication is specified using a reserved bit in a general constraints information (general_constraints_info( )) syntax structure.

21. The method of any of claims 1-20, wherein the indication is specified using a bit in a video usability information (VUI) parameters (vui_parameters( )) syntax structure specified in a versatile SEI (VSEI) message.

22. The method of any of claims 1-21, wherein the indication is specified in semantics of a VUI non packed constraint flag (vui_non_packed_constraint_flag) included in a vui_parameters( ) syntax structure specified in a versatile SEI (VSEI) message, and wherein the semantics include one or more of the following: vui_non_packed_constraint_flag equal to 1 specifies that there shall not be any frame packing arrangement SEI messages or GFV SEI messages present in the bitstream that applies to the CLVS; and vui_non_packed_constraint_flag equal to 0 does not impose such a constraint.

23. The method of any of claims 1-22, wherein the indication is specified in an SEI manifest SEI message, and wherein the indication includes setting a manifest SEI payload type for a value of i (manifest_sei_payload_type[ i ]) to be equal to an SEI payloadType value of the GFV SEI message.

24. The method of any of claims 1-23, wherein the indication is further specified by setting for a manifest SEI description value of i (manifest_sei_description[ i ]) to be equal to one.

25. The method of any of claims 1-24, wherein the conversion includes encoding the video into the bitstream.

26. The method of any of claims 1-24, wherein the conversion includes decoding the video from the bitstream.

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 claims 1-26.

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 claims 1-26.

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 that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; and generating a bitstream based on the the indication.

30. A method for storing bitstream of a video comprising: determining that a generative face video (GFV) supplemental enhancement information (SEI) message includes an ith GFV chroma key threshold value (gfv_chroma_key_thr_value[ i ]) where a value of the gfv_chroma_key_thr_value[ i ] shall be in a range of zero to 255; generating a bitstream based on the indication; and storing the bitstream in a non-transitory computer-readable recording medium.

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