Signaling of neural network post-processing filter purposes and output chroma formats

Abstract

A mechanism for processing video data is disclosed. The mechanism includes determining a value of an NNPFC output chroma component block flag (nnpfcount subcflag) in a neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message, where the value of the nnpfcount subcflag should be equal to 1 when a chroma format identification code (ChromaFormatIdc) is equal to 2, an indication color format is a 4: 2: 2 format, and there is the NNPFC output chroma component block flag (nnpfcount subcflag). A conversion between the visual media data and the bitstream is performed on the basis of the nnpfoutsubcflag.

Description

[0001] Cross-application of related applications

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 398,109, filed on August 15, 2022, the teachings and disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] This patent document relates to the generation, storage and consumption of digital audio-visual media information in file format. Background Art

[0004] Digital video consumes the largest amount of bandwidth used on the Internet and other digital communications networks. As the number of connected user devices capable of receiving and displaying video increases, the demand for bandwidth used by digital video is likely to continue to grow. Summary of the invention

[0005] The first aspect relates to a method for processing video data, comprising: determining a value of a neural network post-processing filter characteristic (NNPFC) output chroma component block flag (nnpfc_out_sub_c_flag) in a supplemental enhancement information (SEI) message of an NNPFC, wherein when a chroma format identification code (ChromaFormatIdc) is equal to 2, indicating that the color format is a 4:2:2 format, and when the NNPFC output chroma component block flag (nnpfc_out_sub_c_flag) is present, the value of nnpfc_out_sub_c_flag should be equal to 1; and performing conversion between visual media data and a bitstream based on nnpfc_out_sub_c_flag.

[0006] A second aspect relates to a non-transitory computer-readable recording medium storing a bitstream of a video, the bitstream of the video being generated by a method performed by a video processing device, wherein the method includes: determining a value of a neural network post-processing filter characteristic (NNPFC) output chroma component block flag (nnpfc_out_sub_c_flag) in a NNPFC supplemental enhancement information (SEI) message, wherein when a chroma format identification code (ChromaFormatIdc) is equal to 2 and the NNPFC output chroma component block flag (nnpfc_out_sub_c_flag) is present, the value of nnpfc_out_sub_c_flag should be equal to 1; and generating a bitstream based on the determination.

[0007] A third aspect relates to an apparatus for processing video data, the apparatus comprising: a processor; and a non-transitory memory having instructions thereon, wherein when the instructions are executed by the processor, the processor is caused to perform any one of the aforementioned aspects.

[0008] A fourth aspect provides a non-transitory computer-readable medium, comprising a computer program product for use by a video codec device, the computer program product comprising computer executable instructions stored on the non-transitory computer-readable medium, such that when the instructions are executed by a processor, the video codec device performs a method according to any one of the preceding aspects.

[0009] A fifth aspect relates to a method for storing a bitstream of a video, comprising: determining a value of a neural network post-processing filter characteristic (NNPFC) output chroma component block flag (nnpfc_out_sub_c_flag) in a supplemental enhancement information (SEI) message of an NNPFC, wherein when a chroma format identification code (ChromaFormatIdc) is equal to 2 and the NNPFC output chroma component block flag (nnpfc_out_sub_c_flag) exists, the value of nnpfc_out_sub_c_flag should be equal to 1; generating a bitstream based on the determination; and storing the bitstream in a non-temporary computer-readable recording medium.

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

[0011]

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

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

[0013] Figure 1 is an example illustration of the luma data channel with nnpfc_inp_order_idc equal to 3.

[0014] Figure 2 is a block diagram illustrating an example video processing system.

[0015] Figure 3 is a block diagram of an example video processing device.

[0016] Figure 4 is a flow chart of an example method of video processing.

[0017] Figure 5 is a block diagram illustrating an example video codec system.

[0018] Figure 6 is a schematic diagram illustrating an example encoder.

[0019] Figure 7 is a schematic diagram illustrating an example decoder.

[0020] Figure 8 is a schematic diagram of an example encoder.

[0021] Fig. 9 is a flow chart of an example method of video processing. DETAILED DESCRIPTION

[0022] First, it should be understood that although illustrative implementations 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 present disclosure should not be limited in any way to the exemplary implementations, drawings, and techniques shown below, including the exemplary designs and implementations shown and described herein, but may be modified within the scope of the appended claims and their full scope of equivalents.

[0023] Section headings are used in this document for ease of understanding and do not limit the applicability of the techniques and embodiments disclosed in each section to only that section. In addition, the use of H.266 technical terms in some descriptions is solely for ease of understanding and is not intended to limit the scope of the disclosed techniques. Therefore, the techniques described herein are also applicable to other video codec protocols and designs. In this document, editorial changes to text relative to a draft of the Versatile Video Coding (VVC) specification or an ISOBMFF file format specification based on the International Organization for Standardization (ISO), are indicated by bold italics for cancelled text and bold underlines for added text.

[0024] 1. Preliminary Discussion

[0025] This document relates to image and / or video codec technology. In particular, the present disclosure relates to signaling the purpose of a neural network post-processing filter and the output chroma format signaled in a video bitstream. These examples can be applied individually or in various combinations for video bitstreams encoded and decoded by any codec, such as the VVC standard and / or the Versatile SEI Messages for Coded Video Bitstreams (VSEI) standard.

[0026] 2. Abbreviations

[0027] 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), Picture Parameter Set (PPS), Picture Unit (PU), Random Access Skipped Leading (RASL), Supplemental Enhancement Information (SEI), Step-wise Temporal Sublayer Access (STSA), Video Coding Layer (VCL), such as Rec.ITU-T H.274|ISO / IEC Versatile Supplemental Enhancement Information (VSEI) as described in ITU-T H.266 ISO / IEC 23002-7, Video Usability Information (VUI), Versatile Video Codec (VVC) as described in Rec. ITU-T H.266 ISO / IEC 23090-3.

[0028] 3. Further Discussion

[0029] 3.1 Video Codec Standards

[0030] Video codec standards have evolved primarily through the development of standards by the International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T) and the International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC). ITU-T produced the H.261 and H.263 standards, ISO / IEC produced the Moving Picture Experts Group (MPEG)-1 and MPEG-4 Visual standards, and the two organizations jointly produced the H.262 / MPEG-2 Video standard, the H.264 / MPEG-4 Advanced Video Coding (AVC) standard, and the H.265 / High Efficiency Video Coding (HEVC) [1] standard. Starting with H.262, video codec standards are based on a hybrid video codec structure that utilizes temporal prediction plus transform coding. To explore future video codec technologies beyond HEVC, the Video Codec Experts Group (VCEG) and MPEG jointly established the Joint Video Exploration Team (JVET). JVET adopted many new methods and incorporated them into a reference software called the Joint Exploration Model (JEM) [2]. JVET was later renamed the Joint Video Experts Team (JVET) when the Versatile Video Codec (VVC) project was officially launched. VVC [3] is a codec standard that aims to reduce bitrate by 50% compared to HEVC.

[0031] The Versatile Video Codec (VVC) standard (ITU-T H.266 | ISO / IEC 23090-3) [3][4] and the related Versatile Supplementary Enhancement Information (VSEI) standard (ITU-T H.274 | ISO / IEC 23002-7) [4] are designed for the widest range of applications, including traditional uses such as television broadcasting, video conferencing or playback from storage media, as well as newer and more advanced use cases such as adaptive bitrate streaming, video region extraction, composition and merging of content from multiple codec video bitstreams, multi-view video, scalable layered codecs and viewport-adaptive 360° immersive media.

[0032] The Essential Video Coding (EVC) standard (ISO / IEC 23094-1) is another video codec standard developed by MPEG.

[0033] 3.2 SEI Messages in General and VVC and VSEI

[0034] SEI messages facilitate processes related to decoding, display, or other purposes. However, SEI messages are not required to construct luma or chroma samples by the decoding process. Conformant decoders do not need to process this information to achieve output order conformance. Some SEI messages are required to check bitstream conformance and output timing decoder conformance. Other SEI messages are not required to check bitstream conformance.

[0035] Annex D of VVC specifies the syntax and semantics of the SEI message payload of some SEI messages, and specifies the use of SEI messages and VUI parameters whose syntax and semantics are specified in ITU-T H.274 | ISO / IEC 23002-7.

[0036] 3.3 Signaling of Neural Network Post-Processing Filters

[0037] JVET-AA2006 [5] includes the specification of two SEI messages for signaling of neural network post-processing filters, as shown below.

[0038] 8.28 Neural Network Post-Processing Filter Characteristics SEI Message

[0039] 8.28.1 Neural Network Post-Processing Filter Characteristics SEI Message Syntax

[0040]

[0041]

[0042]

[0043] 8.28.2 Neural Network Post-Processing Filter Characteristics SEI Message Semantics

[0044] This SEI message specifies a neural network that can be used as a post-processing filter. The Activate with Neural Network Post-Processing Filter SEI message indicates the use of the specified post-processing filter for a particular picture.

[0045] The following variables need to be defined for use with this SEI message: - The width and height of the cropped decoded output picture in units of luma samples, denoted herein by CroppedWidth and CroppedHeight, respectively. - The luma sample array CroppedYPic[x][y] and the chroma sample arrays CroppedCbPic[x][y] and CroppedCrPic[x][y] (when present) of the cropped decoded output picture for vertical coordinate y and horizontal coordinate x, where the top left corner coordinate y of the sample array is equal to 0 and x is equal to 0. - The bit depth BitDepthY of the luma sample array of the cropped decoded output picture. - The bit depth BitDepthC of the chroma sample arrays (if any) of the cropped decoded output picture. - The chroma format indicator, denoted herein by ChromaFormatIdc, as described in clause 7.3. - The quantized strength value StrengthControlVal when nnpfc_auxiliary_inp_idc is equal to 1.

[0046] When this SEI message specifies a neural network that can be used as a post-processing filter, the semantics specify the derivation of the luma sample array FilteredYPic[x][y] and the chroma sample arrays FilteredCbPic[x][y] and FilteredCrPic[x][y] containing the output of the post-processing filter, as indicated by the value of nnpfc_out_order_idc. The variables SubWidthC and SubHeightC are derived from ChromaFormatIdc, as specified in Table 2.

[0047] nnpfc_id contains an identification number that can be used to identify the post-processing filter. The value of nnpfc_id should be from 0 to 2. 32 -2 (including 0 and 2 32 -2). From 256 to 511 (including 256 and 511) and from 2 31 To 2 32 -2 (including 2 31 and 2 32 -2) are reserved for future use by ITU-T|ISO / IEC. When a value in the range from 256 to 511 (inclusive) and from 2 31 To 2 32 -2 (including 2 31 and 2 32-2), the decoder shall ignore the value of nnpfc_id. nnpfc_mode_idc equal to 0 specifies that the post-processing filter associated with the nnpfc_id value is determined by external means not specified in this document. nnpfc_mode_idc equal to 1 specifies that the post-processing filter associated with the nnpfc_id value is a neural network represented by the ISO / IEC 15938-17 bitstream contained in this SEI message.

[0048] nnpfc_mode_idc equal to 2 specifies that the post-processing filter associated with the nnpfc_id value is a neural network identified by the specified tag uniform resource identifier (URI) (nnpfc_uri_tag[i]) and the neural network information URI (nnpfc_uri[i]). The value of nnpfc_mode_idc shall be in the range from 0 to 255, inclusive. Values ​​of nnpfc_mode_idc greater than 2 are reserved by ITU-T|ISO / IEC for future specification and shall not appear in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_mode_idc. nnpfc_purpose_and_formatting_flag equal to 0 specifies that there are no syntax elements related to filter purpose, input formatting, output formatting, and complexity. nnpfc_purpose_and_formatting_flag equal to 1 specifies that there are syntax elements related to filter purpose, input formatting, output formatting, and complexity. nnpfc_purpose_and_formatting_flag shall be equal to 1 when nnpfc_mode_idc is equal to 1 and the current CLVS does not contain a previous neural network post-processing filter characteristics SEI message in decoding order with a value of nnpfc_id equal to the value of nnpfc_id in this SEI message.

[0049] When the current CLVS contains a previous neural network post-processing filter characteristics SEI message with a nnpfc_id value equal to the nnpfc_id value in this SEI message, in decoding order, at least one of the following conditions shall apply: - The SEI message has nnpfc_mode_idc equal to 1 and nnpfc_purpose_and_formatting_flag equal to 0, so as to provide a neural network update. - This SEI message has the same content as the previous neural network post-processing filter characteristics SEI message. When this SEI message is the first neural network post-processing filter characteristics SEI message with a particular nnpfc_id value within the current CLVS, in decoding order, the SEI message specifies the base post-processing filters that are applicable to the current decoded picture and all subsequent decoded pictures in the current layer in output order until the end of the current CLVS. When this SEI message is not the first neural network post-processing filter characteristics SEI message with a particular nnpfc_id value within the current CLVS in decoding order, this SEI message applies to the current decoded picture and all subsequent decoded pictures in the current layer in output order until the end of the current CLVS or until the end of the next neural network post-processing filter characteristics SEI message in output order with that particular nnpfc_id value within the current CLVS.

[0050] nnpfc_purpose indicates the purpose of the post-processing filter as specified in Table 20. The value of nnpfc_purpose shall be in the range from 0 to 2. 32 -2 (including 0 and 2 32 -2). Values ​​of nnpfc_purpose not appearing in Table 20 are reserved by ITU-T|ISO / IEC for future specification and shall not appear in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_purpose.

[0051] Table 20 – Definition of nnpfc_purpose

[0052]

[0053] NOTE 1—When the reserved value of nnpfc_purpose is used by ITU-T ISO / IEC in the future, the syntax of this SEI message may be extended with a syntax element whose presence is conditional on nnpfc_purpose being equal to the reserved value.

[0054] When SubWidthC is equal to 1 and SubHeightC is equal to 1, nnpfc_purpose shall not be equal to 2 or 4. nnpfc_out_sub_c_flag equal to 1 specifies that outSubWidthC is equal to 1 and outSubHeightC is equal to 1. nnpfc_out_sub_c_flag equal to 0 specifies that outSubWidthC is equal to 2 and outSubHeightC is equal to 1. When nnpfc_out_sub_c_flag is not present, outSubWidthC is inferred to be equal to SubWidthC and outSubHeightC is inferred to be equal to SubHeightC. When SubWidthC is equal to 2 and SubHeightC is equal to 1, nnpfc_out_sub_c_flag shall not be equal to 0.

[0055] nnpfc_pic_width_in_luma_samples and nnpfc_pic_height_in_luma_samples specify the width and height, respectively, of the array of luma samples of the picture obtained by applying the post-processing filter identified by nnpfc_id to the cropped decoded output picture. When nnpfc_pic_width_in_luma_samples and nnpfc_pic_height_in_luma_samples are not present, they are inferred to be equal to CroppedWidth and CroppedHeight, respectively. nnpfc_component_last_flag equal to 0 specifies that the second dimension in the input tensor inputTensor to the post-processing filter and the output tensor outputTensor produced by the post-processing filter is used for this channel. nnpfc_component_last_flag equal to 1 specifies that the last dimension in the input tensor inputTensor to the post-processing filter and the output tensor outputTensor produced by the post-processing filter is used for this channel.

[0056] NOTE 2 - The first dimension in the input and output tensors is used for batch indexing, which is a practice in some neural network frameworks. While the semantics of this SEI message uses a batch size equal to 1, it is up to the post-processing implementation to determine the batch size used as input to inference into the neural network. NOTE 3 - Color components are examples of channels.

[0057] nnpfc_inp_format_flag indicates the method of converting the sample values ​​of the cropped decoded output picture into the input values ​​of the post-processing filter. When nnpfc_inp_format_flag is equal to 0, the input values ​​of the post-processing filter are real numbers, and the functions InpY and InpC are specified as follows:

[0058] InpY(x)=x÷((1< <BitDepth Y )-1) (75)

[0059] InpC(x)=x÷((1< <BitDepth C )-1) (76)

[0060] When nnpfc_inp_format_flag is equal to 1, the input values ​​to the post-processing filters are unsigned integers, and the functions InpY and InpC are specified as follows:

[0061]

[0062] The variable inpTensorBitDepth is derived from the syntax element nnpfc_inp_tensor_bitdepth_minus8 as specified below. nnpfc_inp_tensor_bitdepth_minus8 plus 8 specifies the bit depth of the luma sample values ​​in the input integer tensor. The value of inpTensorBitDepth is derived as follows:

[0063] inpTensorBitDepth=nnpfc_inp_tensor_bitdepth_minus8+8 (78)

[0064] A bitstream conformance requirement is that the value of nnpfc_inp_tensor_bitdepth_minus8 should be in the range from 0 to 24, inclusive.

[0065] nnpfc_auxiliary_inp_idc not equal to 0 specifies that auxiliary input data is present in the input tensor of the neural network post-processing filter. nnpfc_auxiliary_inp_idc equal to 0 indicates that auxiliary input data is not present in the input tensor. nnpfc_auxiliary_inp_idc equal to 1 specifies that the auxiliary input data is derived as specified in Table 23. The value of nnpfc_auxiliary_inp_idc shall be in the range from 0 to 255, inclusive. Values ​​of nnpfc_auxiliary_inp_idc greater than 1 are reserved by ITU-T|ISO / IEC for future specification and shall not appear in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_auxiliary_inp_idc.

[0066] nnpfc_separate_colour_description_present_flag equal to 1 indicates that a different combination of color primaries, transfer characteristics, and matrix coefficients for the picture produced by the post-processing filters is specified in the SEI message syntax structure. nnfpc_separate_colour_description_present_flag equal to 0 indicates that the combination of color primaries, transfer characteristics, and matrix coefficients for the picture produced by the post-processing filters is the same as indicated in the VUI parameters of the CLVS.

[0067] nnpfc_colour_primaries has the same semantics as specified for the vui_colour_primaries syntax element in clause 7.3, except for the following: - nnpfc_colour_primaries specifies the colour primaries of the picture resulting from applying the neural network post-processing filters specified in the SEI message, instead of the colour primaries used for CLVS. - When nnpfc_colour_primaries is not present in the neural network post-processing filter characteristics SEI message, the value of nnpfc_colour_primaries is inferred to be equal to vui_colour_primaries. nnpfc_transfer_characteristics has the same semantics as specified for the vui_transfer_characteristics syntax element in clause 7.3, except for the following: - nnpfc_transfer_characteristics specifies the transfer characteristics of the picture resulting from applying the neural network post-processing filters specified in the SEI message, instead of the transfer characteristics used for CLVS. - When nnpfc_transfer_characteristics is not present in the neural network post-processing filter characteristics SEI message, the value of nnpfc_transfer_characteristics is inferred to be equal to vui_transfer_characteristics.

[0068] nnpfc_matrix_coeffs has the same semantics as specified for the vui_matrix_coeffs syntax element in clause 7.3, with the following exceptions: - nnpfc_matrix_coeffs specifies the matrix coefficients of the picture resulting from applying the neural network post-processing filters specified in the SEI message, rather than the matrix coefficients for CLVS. - When nnpfc_matrix_coeffs is not present in the neural network post-processing filter characteristics SEI message, the value of nnpfc_matrix_coeffs is inferred to be equal to vui_matrix_coeffs. - The allowed values ​​of nnpfc_matrix_coeffs are not constrained by the chroma format of the decoded video picture, which is indicated by the value of ChromaFormatIdc for the semantics of the VUI parameters. - When nnpfc_matrix_coeffs is equal to 0, nnpfc_out_order_idc shall not be equal to 1 or 3.

[0069] nnpfc_inp_order_idc indicates a method for sorting the sample array of the cropped decoded output picture as the input to the post-processing filter. Table 21 contains an informative description of the nnpfc_inp_order_idc value. The semantics of nnpfc_inp_order_idc in the range from 0 to 3 (including 0 and 3) are specified in Table 23, which specifies the process of deriving the input tensor inputTensor for different values ​​of nnpfc_inp_order_idc for a given vertical sample coordinate cTop and horizontal sample coordinate cLeft, where the vertical sample coordinate cTop and the horizontal sample coordinate cLeft specify the upper left sample position of the sample block (Patch) included in the input tensor. When the chroma format of the cropped decoded output picture is not 4:2:0, nnpfc_inp_order_idc should not be equal to 3. The value of nnpfc_inp_order_idc should be in the range from 0 to 255 (including 0 and 255). Values ​​of nnpfc_inp_order_idc greater than 3 are reserved by ITU-T|ISO / IEC for future specification and shall not be present in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_inp_order_idc.

[0070] Table 21 - Informative description of nnpfc_inp_order_idc values

[0071]

[0072]

[0073] Figure 1 is an example diagram 100 of a luma data channel with nnpfc_inp_order_idc equal to 3 (informative).

[0074] A patch is a rectangular array of samples of a component (e.g., luma component or chroma component) from a picture. nnpfc_constant_patch_size_flag equal to 0 specifies that the post-processing filter accepts any block size that is a positive integer multiple of the block size indicated by nnpfc_patch_width_minus1 and nnpfc_patch_height_minus1 as input. When nnpfc_constant_patch_size_flag is equal to 0, the block size width shall be less than or equal to CroppedWidth. When nnpfc_constant_patch_size_flag is equal to 0, the block size height shall be less than or equal to CroppedHeight. nnpfc_constant_patch_size_flag equal to 1 specifies that the post-processing filter accepts exactly the block size indicated by nnpfc_patch_width_minus1 and nnpfc_patch_height_minus1 as input.

[0075] When nnpfc_constant_patch_size_flag is equal to 1, nnpfc_patch_width_minus1+1 specifies the horizontal sample count of the block size required for the post-processing filter input. When nnpfc_constant_patch_size_flag is equal to 0, any positive integer multiple of (nnpfc_patch_width_minus1+1) can be used as the horizontal sample count of the block size used for the post-processing filter input. The value of nnpfc_patch_width_minus1 should be in the range from 0 to Min(32766, CroppedWidth-1), inclusive. When nnpfc_constant_patch_size_flag is equal to 1, nnpfc_patch_height_minus1+1 specifies the vertical sample count of the block size required for the post-processing filter input. When nnpfc_constant_patch_size_flag is equal to 0, any positive integer multiple of (nnpfc_patch_height_minus1+1) can be used as the vertical sample count of the block size for the post-processing filter input. The value of nnpfc_patch_height_minus1 should be in the range from 0 to Min(32766,CroppedHeight-1), inclusive. nnpfc_overlap specifies the overlapping horizontal and vertical sample counts of adjacent input tensors to the post-processing filter. The value of nnpfc_overlap should be in the range from 0 to 16383, inclusive.

[0076] The variables inpPatchWidth, inpPatchHeight, outPatchWidth, outPatchHeight, horCScaling, verCScaling, outPatchCWidth, outPatchCHeight, and overlapSize are derived as follows:

[0077]

[0078]

[0079] The requirement for bitstream conformance is that outPatchWidth*CroppedWidth shall be equal to nnpfc_pic_width_in_luma_samples*inpPatchWidth, and outPatchHeight*CroppedHeight shall be equal to nnpfc_pic_height_in_luma_samples*inpPatchHeight. nnpfc_padding_type specifies the padding process when referencing sample positions outside the boundaries of the cropped decoded output picture as described in Table 22. The value of nnpfc_padding_type shall be in the range from 0 to 15, inclusive.

[0080] Table 22 - Informative description of nnpfc_padding_type values

[0081] nnpfc_padding_type describe 0 Zero padding 1 Copy Fill 2 Reflection Fill 3 Wrap-around filling 4 Fixed padding 5..15 reserve

[0082] nnpfc_luma_padding_val specifies the luma value used for padding when nnpfc_padding_type is equal to 4. nnpfc_cb_padding_val specifies the Cb value used for padding when nnpfc_padding_type is equal to 4. nnpfc_cr_padding_val specifies the Cr value used for padding when nnpfc_padding_type is equal to 4.

[0083] The function InpSampleVal(y,x,picHeight,picWidth,croppedPic) whose input is the vertical sample point position y, the horizontal sample point position x, the picture height picHeight, the picture width picWidth and the sample point array croppedPic returns the value of sampleVal derived as follows:

[0084]

[0085]

[0086] Table 23 - Process of deriving the input tensor inputTensor for a given vertical sample point coordinate cTop and horizontal sample point coordinate cLeft, where the vertical sample point coordinate cTop and the horizontal sample point coordinate cLeft specify the top left sample point position of the sample point block included in the input tensor

[0087]

[0088]

[0089]

[0090]

[0091]

[0092] nnpfc_complexity_idc greater than 0 specifies that there may be one or more syntax elements indicating the complexity of the post-processing filter associated with nnpfc_id. nnpfc_complexity_idc equal to 0 specifies that there are no syntax elements indicating the complexity of the post-processing filter associated with nnpfc_id. The value nnpfc_complexity_idc shall be in the range from 0 to 255, inclusive. Values ​​of nnpfc_complexity_idc greater than 1 are reserved by ITU-T|ISO / IEC for future specification and shall not appear in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_complexity_idc.

[0093] nnpfc_out_format_flag equal to 0 indicates that the sample values ​​output by the post-processing filter are real numbers, and the functions OutY and OutC for converting the luma sample values ​​and chroma sample values ​​output by the post-processing to integer values ​​at bit depths BitDepthY and BitDepthC, respectively, are specified as follows:

[0094] OutY( x ) = Clip3( 0, ( 1 << BitDepth Y ) - 1, Round( x * ( ( 1 < <BitDepth Y ) - 1 ) ) ) (81)

[0095] OutC( x )= Clip3( 0, ( 1 << BitDepth C ) - 1, Round( x * ( ( 1 < <BitDepth C ) - 1 ) ) ) (82)

[0096] nnpfc_out_format_flag equal to 1 indicates that the sample values ​​output by the post-processing filter are unsigned integers, and the functions OutY and OutC are specified as follows:

[0097]

[0098] The variable outTensorBitDepth is derived from the syntax element npfc_out_tensor_bitdepth_minus8 as described below. nnpfc_out_tensor_bitdepth_minus8 plus 8 specifies the bit depth of the sample values ​​in the output integer tensor. The value of outTensorBitDepth is derived as follows:

[0099] outTensorBitDepth = nnpfc_out_tensor_bitdepth_minus8 + 8 (84)

[0100] A bitstream conformance requirement is that the value of nnpfc_out_tensor_bitdepth_minus8 should be in the range from 0 to 24, inclusive.

[0101] nnpfc_out_order_idc indicates the output order of samples produced by the post-processing filter. Table 24 contains an informative description of the nnpfc_out_order_idc values. The semantics of nnpfc_out_order_idc in the range from 0 to 3 (including 0 and 3) are specified in Table 25, which specifies the process of deriving the sample values ​​in the filtered output sample arrays FilteredYPic, FilteredCbPic and FilteredCrPic from the output tensor outputTensor for different values ​​of nnpfc_out_order_idc for a given vertical sample coordinate cTop and horizontal sample coordinate cLeft, where the vertical sample coordinate cTop and the horizontal sample coordinate cLeft specify the top left sample position of the sample block included in the input tensor. - When nnpfc_purpose is equal to 2 or 4, nnpfc_out_order_idc shall not be equal to 3. The value of nnpfc_out_order_idc shall be in the range from 0 to 255, inclusive. Values ​​of nnpfc_out_order_idc greater than 3 are reserved by ITU-T|ISO / IEC for future specification and shall not be present in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_out_order_idc.

[0102] Table 24 - Informative description of nnpfc_out_order_idc values

[0103]

[0104] Table 25 - Process of deriving sample values ​​in the filtered output sample arrays FilteredYPic, FilteredCbPic and FilteredCrPic from the output tensor outputTensor for a given vertical sample coordinate cTop and horizontal sample coordinate cLeft, where the vertical sample coordinate cTop and the horizontal sample coordinate cLeft specify the top left sample position of the sample block included in the input tensor

[0105]

[0106]

[0107]

[0108] The base post-processing filter used for the cropped decoded output picture picA is the filter identified by the first neural network post-processing filter characteristics SEI message with a specific nnpfc_id value within CLVS in decoding order.

[0109] If there is another neural network post-processing filter characteristics SEI message with the same nnpfc_id value, with nnpfc_mode_idc equal to 1, with different content than the neural network post-processing filter characteristics SEI message defining the base post-processing filter and applicable to the picture picA, the base post-processing filter is updated by decoding the ISO / IEC 15938-17 bitstream in the neural network post-processing filter SEI message to obtain the post-processing filter PostProcessingFilter(). Otherwise, the post-processing filter PostProcessingFilter() is assigned to be the same as the base post-processing filter.

[0110] The following process is used to filter the cropped decoded output picture using a post-processing filter PostProcessingFilter() to generate a filtered picture, which contains Y, Cb and Cr sample arrays FilteredYPic, FilteredCbPic and FilteredCrPic, respectively, as indicated by nnpfc_out_order_idc.

[0111]

[0112]

[0113] nnpfc_reserved_zero_bit should be equal to 0.

[0114] nnpfc_uri_tag[i] contains a null-terminated UTF-8 string specifying a tag URI. The Unicode Transformation Format (UTF)-8 string contains a URI whose syntax and semantics are as specified in Internet Engineering Task Force (IETF) Request For Comment (RFC) 4151, uniquely identifying the format and associated information about the neural network used as a post-processing filter specified by the nnrpf_uri[i] value. NOTE 4 - The nnrpf_uri_tag[i] element represents a 'tag' URI that allows the format of the neural network data specified by the nnrpf_uri[i] value to be uniquely identified without the need for a central registration authority. nnpfc_uri[i] contains a null-terminated UTF-8 string as specified in IETF Internet Standard 63. The UTF-8 string contains a URI whose syntax and semantics are as specified in IETF Internet Standard 66, identifying neural network information (e.g., data representation) used as a post-processing filter. nnpfc_payload_byte[i] contains the i-th byte of a bitstream conforming to ISO / IEC 15938-17. The byte sequence nnpfc_payload_byte[i] for all current values ​​of i shall be a complete bitstream conforming to ISO / IEC 15938-17.

[0115] nnpfc_parameter_type_idc equal to 0 indicates that the neural network uses only integer parameters. nnpfc_parameter_type_flag equal to 1 indicates that the neural network can use floating point or integer parameters. nnpfc_parameter_type_idc equal to 2 indicates that the neural network uses only binary parameters. nnpfc_parameter_type_idc equal to 3 is reserved by ITU-T|ISO / IEC for future specification and shall not appear in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing the reserved value of nnpfc_parameter_type_idc. nnpfc_log2_parameter_bit_length_minus3 equal to 0, 1, 2, and 3 indicates that the neural network does not use parameters with a bit length greater than 8, 16, 32, and 64, respectively. When nnpfc_parameter_type_idc is present and nnpfc_log2_parameter_bit_length_minus3 is not present, the neural network does not use parameters with a bit length greater than 1. nnpfc_num_parameters_idc indicates the maximum number of neural network parameters for the post-processing filters in powers of 2048. nnpfc_num_parameters_idc equal to 0 indicates that the maximum number of neural network parameters is unspecified. The value nnpfc_num_parameters_idc shall be in the range from 0 to 52, inclusive. Values ​​of nnpfc_num_parameters_idc greater than 52 are reserved by ITU-T|ISO / IEC for future specification and shall not appear in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_num_parameters_idc. If the value of nnpfc_num_parameters_idc is greater than zero, the variable maxNumParameters is derived as follows:

[0116] maxNumParameters=(2048< <nnpfc_num_parameters_idc)–1 (86)

[0117] A bitstream conformance requirement is that the number of neural network parameters of the post-processing filter shall be less than or equal to maxNumParameters. nnpfc_num_kmac_operations_idc greater than 0 specifies that the maximum number of multiply-accumulate operations per sample of the post-processing filter is less than or equal to nnpfc_num_kmac_operations_idc × 1000. nnpfc_num_kmac_operations_idc equal to 0 indicates that the maximum number of multiply-accumulate operations of the network is unspecified. The value of nnpfc_num_kmac_operations_idc shall be in the range from 0 to 2. 32 -1 (including 0 and 2 32 -1).

[0118] 8.29 Neural Network Post-Processing Filter Activation SEI Message

[0119] 8.29.1 Neural Network Post-Processing Filter Activation SEI Message Syntax

[0120] nn_post_filter_activation(payloadSize){ Descriptors nnpfa_id ue(v) }

[0121] 8.29.2 Neural Network Post-Processing Filter Activation SEI Message Semantics

[0122] This SEI message specifies the neural network post-processing filters that can be used for post-processing filtering of the current picture. The neural network post-processing filter activation SEI message persists only for the current picture. NOTE - For example, there may be several neural network post-processing filter activation SEI messages for the same picture when the post-processing filters are used for different purposes or filter different color components. nnpfa_id specifies that the neural network post-processing filters specified by one or more neural network post-processing filter characteristics SEI messages can be used for post-processing filtering for the current picture. This SEI message is applicable to the current picture and has a nnpfc_id equal to nnfpa_id.

[0123] 4. Technical problems solved by the disclosed technical solutions

[0124] The example design of the Neural Network Post-Processing Filter Characteristics (NNPFC) SEI message has the following issues. First, the value of 0 of the syntax element nnpfc_purpose is specified as "unknown or unspecified". However, there is little use in specifying such an "unknown or unspecified" purpose. Note that some aspects related to the case where nnpfc_purpose is equal to 0 (such as the values ​​of outSubWidthC and outSubHeightC) are still specified by the semantics of nnpfc_out_sub_c_flag, regardless of whether nnpfc_purpose is equal to 0. In addition, if the purpose is unknown or unspecified, it is unclear why the encoder includes the entire SEI message in the bitstream in the first place, and how the decoder / client should use such a SEI message. Finally, for extensibility, a reserved value is specified for this syntax element.

[0125] Secondly, the semantics of the nnpfc_out_sub_c_flag syntax element are as follows: nnpfc_out_sub_c_flag equal to 1 specifies that outSubWidthC is equal to 1 and outSubHeightC is equal to 1. nnpfc_out_sub_c_flag equal to 0 specifies that outSubWidthC is equal to 2 and outSubHeightC is equal to 1. When nnpfc_out_sub_c_flag is not present, outSubWidthC is inferred to be equal to SubWidthC and outSubHeightC is inferred to be equal to SubHeightC. When SubWidthC is equal to 2 and SubHeightC is equal to 1, nnpfc_out_sub_c_flag should not be equal to 0. The last sentence specifies constraints on the nnpfc_out_sub_c_flag value. However, it is possible that SubWidthC is equal to 2 and SubHeightC is equal to 1 while nnpfc_out_sub_c_flag does not exist (when nnpfc_purpose is equal to a value that is neither 2 nor 4). In this case, according to the constraint, nnpfc_out_sub_c_flag should be equal to 1, and when nnpfc_out_sub_c_flag is equal to 1, according to the first sentence in the semantics, outSubWidthC is equal to 1 and outSubHeightC is equal to 1. On the other hand, according to the second sentence in the semantics, when nnpfc_out_sub_c_flag is not present, outSubWidthC is inferred to be equal to SubWidthC and outSubHeightC is inferred to be equal to SubHeightC, and therefore in this case, the values ​​of outSubWidthC and outSubHeightC will be inferred to be equal to 2 and 1, respectively. This results in different values ​​according to the first sentence and the last sentence. In short, the constraint specified by the last sentence is contradictory to the second sentence under certain conditions.

[0126] 5. List of solutions and implementation examples

[0127] In order to solve the above problems, the following summarized methods are disclosed. This example should be considered as an example to explain the general concept and should not be interpreted in a narrow way. In addition, these examples can be applied alone or in combination in any way.

[0128] Example 1

[0129] A solution to the first problem is now described. In the example, the value 0 of the syntax element nnpfc_purpose is designated as a special purpose or a reserved purpose.

[0130] Example 2

[0131] In one example, a value of 0 is designated for a specific purpose, such as "visual quality improvement."

[0132] Example 3

[0133] In another example, a value of 0 is designated as reserved.

[0134] Example 4

[0135] Now we describe the solution to the second problem. In the example, one of the following two constraints is specified.

[0136] When SubWidthC is equal to 2 and SubHeightC is equal to 1 (ie, ChromaFormatIdc is equal to 2, indicating that the color format is 4:2:2 format), nnpfc_purpose shall be equal to a value that is neither 2 nor 4 (ie, nnpfc_out_sub_c_flag is not present), or nnpfc_out_sub_c_flag shall not be equal to 0 (ie, nnpfc_out_sub_c_flag shall be equal to 1).

[0137] When ChromaFormatIdc is equal to 2 and nnpfc_out_sub_c_flag is present, the value of nnpfc_out_sub_c_flag shall be equal to 1.

[0138] 6. Examples

[0139] The following are some example embodiments of some of the disclosed items outlined in Examples 1 to 4 in Section 5 above.

[0140] Most of the relevant sections that have been added or modified are in bold, and some of the sections that have been deleted are in bold italics. There may be other changes that are editorial in nature and therefore not highlighted.

[0141] 6.1 First Embodiment

[0142] 8.28 Neural Network Post-Processing Filter Characteristics SEI Message

[0143] 8.28.1 Neural Network Post-Processing Filter Characteristics SEI Message Syntax

[0144]

[0145]

[0146] 8.28.2 Neural Network Post-Processing Filter Characteristics SEI Message Semantics

[0147] This SEI message specifies a neural network that can be used as a post-processing filter. The Activate with Neural Network Post-Processing Filter SEI message indicates the use of the specified post-processing filter for a particular picture. ...

[0149] nnpfc_purpose indicates the purpose of the post-processing filter as specified in Table 20. The value of nnpfc_purpose shall be in the range from 0 to 2. 32 -2 (including 0 and 2 32 -2). Values ​​of nnpfc_purpose not appearing in Table 20 are reserved by ITU-T|ISO / IEC for future specification and shall not appear in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_purpose.

[0150] Table 20 – Definition of nnpfc_purpose

[0151]

[0152]

[0153] NOTE 1—When the reserved value of nnpfc_purpose is used by ITU-T ISO / IEC in the future, the syntax of this SEI message may be extended with a syntax element whose presence is conditional on nnpfc_purpose being equal to the reserved value.

[0154] When SubWidthC is equal to 1 and SubHeightC is equal to 1, nnpfc_purpose shall not be equal to 2 or 4, 1 or 3.

[0155] nnpfc_out_sub_c_flag equal to 1 specifies that outSubWidthC is equal to 1 and outSubHeightC is equal to 1. nnpfc_out_sub_c_flag equal to 0 specifies that outSubWidthC is equal to 2 and outSubHeightC is equal to 1. When nnpfc_out_sub_c_flag is not present, outSubWidthC is inferred to be equal to SubWidthC and outSubHeightC is inferred to be equal to SubHeightC. ...

[0157] nnpfc_out_order_idc indicates the output order of samples generated by the post-processing filters. Table 24 contains an informative description of the nnpfc_inp_order_idc values. The semantics of nnpfc_out_order_idc in the range from 0 to 3 (inclusive) are specified in Table 25, which specifies the process of deriving the sample values ​​in the filtered output sample arrays FilteredYPic, FilteredCbPic, and FilteredCrPic from the output tensor outputTensor for different values ​​of nnpfc_out_order_idc for a given vertical sample coordinate cTop and horizontal sample coordinate cLeft, where the vertical sample coordinate cTop and the horizontal sample coordinate cLeft specify the top left sample position of the sample block included in the input tensor. - When nnpfc_purpose is equal to nnpfc_out_order_idc should not The value of nnpfc_out_order_idc shall be in the range from 0 to 255, inclusive. Values ​​of nnpfc_out_order_idc greater than 3 are reserved by ITU-T|ISO / IEC for future specification and shall not be present in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_out_order_idc. ...

[0159] 6.2 Second Embodiment

[0160] 8.28.2 Neural Network Post-Processing Filter Characteristics SEI Message Semantics

[0161] This SEI message specifies a neural network that can be used as a post-processing filter. The Activate with Neural Network Post-Processing Filter SEI message indicates the use of the specified post-processing filter for a particular picture. ...

[0163] nnpfc_purpose indicates the purpose of the post-processing filter as specified in Table 20. The value of nnpfc_purpose shall be in the range from 0 to 2. 32 -2 (including 0 and 2 32 -2). Values ​​of nnpfc_purpose not appearing in Table 20 are reserved by ITU-T|ISO / IEC for future specification and shall not appear in bitstreams conforming to this version of this specification. Decoders conforming to this version of this specification shall ignore SEI messages containing reserved values ​​of nnpfc_purpose.

[0164] Table 20 – Definition of nnpfc_purpose

[0165]

[0166] NOTE 1—When the reserved value of nnpfc_purpose is used by ITU-T ISO / IEC in the future, the syntax of this SEI message may be extended with a syntax element whose presence is conditional on nnpfc_purpose being equal to the reserved value.

[0167] When SubWidthC is equal to 1 and SubHeightC is equal to 1, nnpfc_purpose should not be equal to 2 or 4.

[0168] nnpfc_out_sub_c_flag equal to 1 specifies that outSubWidthC is equal to 1 and outSubHeightC is equal to 1. nnpfc_out_sub_c_flag equal to 0 specifies that outSubWidthC is equal to 2 and outSubHeightC is equal to 1. When nnpfc_out_sub_c_flag is not present, outSubWidthC is inferred to be equal to SubWidthC and outSubHeightC is inferred to be equal to SubHeightC. ...

[0170] 7. References

[0171] [1] ITU-T and ISO / IEC, “High Efficiency Video Codecs”, Rec. ITU-T H.265 | ISO / IEC 23008-2 (current version).

[0172] [2] J. Chen, E. Alshina, G. J. Sullivan, J.-R. Ohm, and J. Boyce, “Joint Exploration Test Model 7 (JEM7) Algorithm Description,” JVET-G1001, August 2017.

[0173] [3] Rec. ITU-T H.266 | ISO / IEC 23090-3, “Versatile Video Codec”, 2022.

[0174] [4] Rec. ITU-T Rec. H.274 | ISO / IEC 23002-7, “Multifunctional supplementary enhancement information message for coded video bitstreams”, 2022.

[0175] [5] P.Yin, S.McCarthy, W.Husak, K.Konstantinides, T.Lu, F.Pu, A.Arora and T.Shao,

[0176] “AHG9: SEI Processing Order SEI Messages”, JVET Input Document JVET-AA0102, available online:

[0177] https: / / www.jvet-experts.org / doc_end_user / current_document.php?id=11778.

[0178] Figure 2 4000 is a block diagram illustrating 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 system 4000. System 4000 may include an input 4002 for receiving video content. The video content may be received in a raw or uncompressed format, such as 8 or 10 bit multi-component pixel values, or may be received in a compressed or encoded format. Input 4002 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interfaces include wired interfaces such as Ethernet, a passive optical network (PON), and wireless interfaces such as Wi-Fi or a cellular interface.

[0179] System 4000 may include a codec component 4004 that may implement various codecs or encoding methods described in this document. Codec component 4004 may reduce the average bit rate of the video from input 4002 to the output of codec component 4004 to generate a codec representation of the video. Codec technology is therefore sometimes referred to as video compression or video transcoding technology. The output of codec component 4004 may be stored or transmitted via a communication connection as represented by component 4006. The bitstream (or codec) representation of the storage or communication transmission of the video received at input 4002 may be used by component 4008 to generate pixel values ​​or to transmit to a displayable video of display interface 4010. The process of generating a user-visible video from a bitstream representation is sometimes referred to as video decompression. In addition, although some video processing operations are referred to as "codec" operations or tools, it will be understood that codec tools or operations are used at encoders, and the corresponding decoding tools or operations of the inverse codec results will be performed by decoders.

[0180] Examples of peripheral bus interfaces or display interfaces may include Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), DisplayPort, etc. Examples of storage interfaces include Serial Advanced Technology Attachment (SATA), Peripheral Component Interconnect (PCI), Integrated Drive Electronics (IDE) interface, etc. The technology described in this document may be embodied in various electronic devices, such as mobile phones, laptops, smart phones, or other devices capable of performing digital data processing and / or video display.

[0181] Figure 3 4100. The apparatus 4100 may be used to implement one or more methods described herein. The apparatus 4100 may be embodied in a smartphone, a tablet computer, a computer, an Internet of Things (IoT) receiver, etc. The apparatus 4100 may include one or more processors 4102, one or more memories 4104, and a video processing circuit 4106. The processor(s) 4102 may be configured to implement one or more methods described in this document. The memory(s) 4104 may be used to store data and code for implementing the methods and techniques described herein. The video processing circuit 4106 may be used to implement some of the techniques described in this document in a hardware circuit system. In some embodiments, the video processing circuit 4106 may be at least partially included in a processor 4102 (e.g., a graphics coprocessor).

[0182] Figure 4 4200. The method 4200 includes, at step 4202, determining a value of a neural network post-processing filter characteristic (NNPFC) purpose syntax element nnpfc_purpose, wherein when the value is 0, the syntax element nnpfc_purpose is designated as a specific purpose or a reserved purpose. At step 4204, performing conversion between visual media data and a bitstream based on the syntax element nnpfc_purpose.

[0183] It should be noted that the method 4200 may be implemented in an apparatus for processing video data, the apparatus comprising a processor and a non-transitory memory having instructions thereon, such as the video encoder 4400, the video decoder 4500, and / or the encoder 4600. In this case, the instructions, when executed by the processor, cause the processor to perform the method 4200. In addition, the method 4200 may be performed by a non-transitory computer-readable medium including a computer program product for use by a video codec device. The computer program product includes computer executable instructions stored on a non-transitory computer-readable medium, such that when executed by the processor, the video codec device performs the method 4200.

[0184] Figure 5 43 is a block diagram illustrating an example video codec system 4300 that can utilize the techniques of the present disclosure. The video codec system 4300 may include a source device 4310 and a target device 4320. The source device 4310 generates encoded video data, where the source device 4310 may be referred to as a video encoding device. The target device 4320 may decode the encoded video data generated by the source device 4310, where the target device 4320 may be referred to as a video decoding device.

[0185] Source device 4310 may include video source 4312, video encoder 4314 and input / output (I / O) interface 4316. Video source 4312 may include a source, such as a video capture device, an interface for receiving video data from a video content provider, and / or a computer graphics system for generating video data, or a combination of these sources. Video data may include one or more pictures. Video encoder 4314 encodes video data from video source 4312 to generate a bit stream. The bit stream may include a bit sequence that forms a codec representation of video data. The bit stream may include a codec picture and related data. The codec picture is a codec representation of a picture. Related 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. Encoded video data may be directly sent to target device 4320 via network 4330 via I / O interface 4316. Encoded video data may also be stored on storage medium / server 4340 for access by target device 4320.

[0186] The target device 4320 may include an I / O interface 4326, a video decoder 4324, and a display device 4322. The I / O interface 4326 may include a receiver and / or a modem. The I / O interface 4326 may obtain coded video data from the source device 4310 or the storage medium / server 4340. The video decoder 4324 may decode the coded video data. The display device 4322 may display the decoded video data to the user. The display device 4322 may be integrated with the target device 4320, or may be external to the target device 4320 that may be configured to interface with an external display device.

[0187] The video encoder 4314 and the video decoder 4324 may operate according to a video compression standard, such as the High Efficiency Video Codec (HEVC) standard, the Versatile Video Codec (VVC) standard, and other current and / or additional standards.

[0188] Figure 6 is a block diagram showing an example of a video encoder 4400, which may be Figure 54300. Video encoder 4400 may be configured to perform any or all of the techniques of the present disclosure. Video encoder 4400 includes multiple functional components. The techniques described in this disclosure may be shared between 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.

[0189] The functional components of the video encoder 4400 may include a segmentation unit 4401, a prediction unit 4402 (which may include a mode selection unit 4403, a motion estimation unit 4404, a motion compensation unit 4405 and an intra-frame 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 coding and decoding unit 4414.

[0190] In other examples, the video encoder 4400 may include more, fewer, or different functional components. In an example, the prediction unit 4402 may include an intra-block copy (IBC) unit. The IBC unit may perform prediction in IBC mode, where at least one reference picture is a picture in which the current video block is located.

[0191] Furthermore, some components, such as the motion estimation unit 4404 and the motion compensation unit 4405 , may be highly integrated, but are represented separately in the example of the video encoder 4400 for purposes of explanation.

[0192] The segmentation unit 4401 may segment the picture into one or more video blocks. The video encoder 4400 and the video decoder 4500 may support various video block sizes.

[0193] The mode selection unit 4403 may select one of the coding modes (e.g., intra or inter) based on the error result, and provide the resulting intra-coded block or inter-coded block to the residual generation unit 4407 to generate residual block data, and to the reconstruction unit 4412 to reconstruct the coded block for use as a reference picture. In some examples, the mode selection unit 4403 may select a combination of intra and inter prediction modes (CIIP), where the prediction is based on an inter prediction signal and an intra prediction signal. In the case of inter prediction, the mode selection unit 4403 may also select a resolution of the motion vector of the block (e.g., sub-pixel or integer pixel precision).

[0194] In order to perform inter-frame prediction on the current video block, the motion estimation unit 4404 may generate motion information of the current video block by comparing the current video block with one or more reference frames from the buffer 4413. The motion compensation unit 4405 may determine a predicted video block of the current video block based on the motion information and decoded samples of pictures from the buffer 4413 other than the picture associated with the current video block.

[0195] The motion estimation unit 4404 and the motion compensation unit 4405 may perform different operations on the current video block, eg, depending on whether the current video block is in an I slice, a P slice, or a B slice.

[0196] In some examples, the motion estimation unit 4404 may perform unidirectional prediction on the current video block, and the motion estimation unit 4404 may search the reference picture of list 0 or list 1 for the reference video block of the current video block. The motion estimation unit 4404 may then generate a reference index indicating the reference picture containing the reference video block in list 0 or list 1, and a motion vector indicating the spatial displacement between the current video block and the reference video block. The motion estimation unit 4404 may output the reference index, the prediction direction indicator, and the motion vector as the motion information of the current video block. The motion compensation unit 4405 may generate a predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.

[0197] In other examples, the motion estimation unit 4404 may perform bidirectional prediction on the current video block, and the motion estimation unit 4404 may search for a reference video block of the current video block in the reference pictures in list 0, and may also search for another reference video block of the current video block in list 1. The motion estimation unit 4404 may then generate a reference index indicating the reference pictures in list 0 and list 1 containing the reference video block and a motion vector indicating a spatial displacement between the reference video block and the current video block. The motion estimation unit 4404 may output the reference index and the motion vector of the current video block as the motion information of the current video block. The motion compensation unit 4405 may generate a predicted video block of the current video block based on the reference video block indicated by the motion information of the current video block.

[0198] In some examples, motion estimation unit 4404 may output a complete set of motion information for use in a decoding process by a decoder. In some examples, motion estimation unit 4404 may not output a complete set of motion information for the current video. Instead, motion estimation unit 4404 may reference motion information of another video block to signal motion information of the current 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 an adjacent video block.

[0199] In one example, the motion estimation unit 4404 may indicate a value in a syntax structure associated with the current video block that indicates to the video decoder 4500 that the current video block has the same motion information as another video block.

[0200] In another example, the motion estimation unit 4404 may identify another video block and a motion vector difference (MVD) in a syntax structure associated with the current video block. The motion vector difference indicates the 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.

[0201] As discussed above, the video encoder 4400 may predictively signal motion vectors. Two examples of predictive signaling techniques that may be implemented by the video encoder 4400 include Advanced Motion Vector Prediction (AMVP) and Merge mode signaling.

[0202] The intra prediction unit 4406 may perform intra prediction on the current video block. When the intra prediction unit 4406 performs intra prediction on the current video block, the 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.

[0203] The residual generation unit 4407 may generate residual data of 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 corresponding to different sample components of the samples in the current video block.

[0204] In other examples, such as in skip mode, there may be no residual data for the current video block and the residual generation unit 4407 may not perform a subtraction operation.

[0205] The 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 the residual video block associated with the current video block.

[0206] After the transform processing unit 4408 generates a transform coefficient video block associated with the current video block, the 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.

[0207] The inverse quantization unit 4410 and the inverse transform unit 4411 may apply inverse quantization and inverse transform to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block. The reconstruction unit 4412 may add the reconstructed residual video block to corresponding samples of one or more predicted video blocks generated by the prediction unit 4402 to generate a reconstructed video block associated with the current block for storage in the buffer 4413.

[0208] After the reconstruction unit 4412 reconstructs the video block, a loop filtering operation may be performed to reduce video blocking effects in the video block.

[0209] The entropy coding unit 4414 may receive data from other functional components of the video encoder 4400. When the entropy coding unit 4414 receives the data, the entropy coding unit 4414 may perform one or more entropy coding operations to generate entropy coded data and output a bitstream including the entropy coded data.

[0210] Figure 7 is a block diagram showing an example of a video decoder 4500, which may be Figure 5 4300. Video decoder 4500 may be configured to perform any or all of the techniques of the present disclosure. In the example shown, video decoder 4500 includes multiple functional components. The techniques described in this disclosure may be shared between various components of video decoder 4500. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

[0211] In the example shown, the 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 transform unit 4505, a reconstruction unit 4506, and a buffer 4507. In some examples, the video decoder 4500 may perform a decoding process that is generally the reverse of the encoding pass described for the video encoder 4400.

[0212] The entropy decoding unit 4501 may retrieve a coded bitstream. The coded bitstream may include entropy-coded video data (e.g., coded blocks of video data). The entropy decoding unit 4501 may decode the entropy-coded video data, and from the entropy-decoded video data, the motion compensation unit 4502 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. The motion compensation unit 4502 may determine such information, for example, by performing AMVP and Merge modes.

[0213] The motion compensation unit 4502 may generate a motion compensated block, and interpolation may be performed based on an interpolation filter. An identifier of an interpolation filter to be used with sub-pixel precision may be included in a syntax element.

[0214] The motion compensation unit 4502 may calculate interpolation of sub-integer pixels of a reference block using an interpolation filter as used by the video encoder 4400 during encoding of the video block. The motion compensation unit 4502 may determine the interpolation filter used by the video encoder 4400 based on received syntax information and use the interpolation filter to generate a prediction block.

[0215] The motion compensation unit 4502 can use some syntax information to determine the size of the blocks used to encode (multiple) frames and / or (multiple) slices of the encoded video sequence, partitioning information describing how each macroblock of the pictures of the encoded video sequence is partitioned, a mode indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter-frame codec block, and other information used to decode the encoded video sequence.

[0216] The intra prediction unit 4503 may form a prediction block from spatially adjacent blocks using, for example, an intra prediction mode received in the bitstream. The inverse quantization unit 4504 inversely quantizes, i.e., dequantizes, the quantized video block coefficients provided in the bitstream and decoded by the entropy decoding unit 4501. The inverse transform unit 4505 applies an inverse transform.

[0217] The reconstruction unit 4506 may add the residual block to the corresponding prediction block generated by the motion compensation unit 4502 or the intra prediction unit 4503 to form a decoded block. If necessary, a deblocking filter may also be applied to filter the decoded block to remove block artifacts. The decoded video block is then stored in a buffer 4507 to provide a reference block for subsequent motion compensation / intra prediction and also to generate a decoded video for presentation on a display device.

[0218] Figure 8 is a schematic diagram of an example encoder 4600. The encoder 4600 is suitable for implementing VVC technology. The encoder 4600 includes three 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 that uses a predefined filter, the SAO 4604 and the ALF 4606 use the original samples of the current picture to reduce the mean square error between the original samples and the reconstructed samples by adding an offset and applying a finite impulse response (FIR) filter, respectively, using the auxiliary information of the codec to signal the offset and filter coefficients. The ALF 4606 is located at the last processing stage of each picture and can be regarded as a tool that attempts to capture and repair artifacts created by previous stages.

[0219] The encoder 4600 also includes an intra prediction component 4608 and a motion estimation / compensation (ME / MC) component 4610 configured to receive an input video. The intra prediction component 4608 is configured to perform intra prediction, and the ME / MC component 4610 is configured to perform inter prediction using a reference picture obtained from a reference picture buffer 4612. The residual block from the inter prediction or intra prediction is fed to the transform (T) component 4614 and the quantization (Q) component 4616 to generate quantized residual transform coefficients, which are fed to the entropy coding component 4618. The entropy coding component 4618 entropy codes and decodes the prediction result and the quantized transform coefficients and sends them to a video decoder (not shown). The quantization component output from the quantization component 4616 can be fed to the inverse quantization (IQ) component 4620, the inverse transform component 4622, and the reconstruction (REC) component 4624. The REC component 4624 is capable of outputting images to the DF 4602 , SAO 4604 , and ALF 4606 for filtering before these pictures are stored in the reference picture buffer 4612 .

[0220] Fig. 9 4700 is a flow chart of an example method 4700 for video processing. The method 4700 includes, at step 4702, determining a value of nnpfc_out_sub_c_flag in an NNPFC SEI message. When ChromaFormatIdc is equal to 2, indicating that the color format is 4:2:2, and nnpfc_out_sub_c_flag is present, the value of nnpfc_out_sub_c_flag should be equal to 1. At step 4704, conversion between visual media data and a bitstream is performed based on the nnpfc_out_sub_c_flag element.

[0221] It should be noted that method 4700 may be implemented in an apparatus for processing video data, the apparatus comprising a processor and a non-transitory memory having instructions thereon, such as video encoder 4400, video decoder 4500, and / or encoder 4600. In this case, the instructions, when executed by the processor, cause the processor to perform method 4700. In addition, method 4700 may be performed by a non-transitory computer-readable medium comprising a computer program product for use by a video codec device. The computer program product comprises computer executable instructions stored on a non-transitory computer-readable medium, such that when executed by a processor, the video codec device performs method 4700.

[0222] Next a list of preferred solutions with some examples is provided.

[0223] The following solutions illustrate examples of the techniques discussed herein.

[0224] 1. A method for processing media data, comprising: determining a value of a neural network post-processing filter characteristic (NNPFC) purpose syntax element nnpfc_purpose, wherein when the value is 0, the syntax element nnpfc_purpose is designated as a specific purpose or a reserved purpose; and performing conversion between visual media data and a bitstream based on the syntax element nnpfc_purpose.

[0225] 2. The method according to solution 1, wherein when the value is zero, the syntax element nnpfc_purpose is specified as visual quality improvement.

[0226] 3. The method according to solution 1 or 2, wherein when the value is zero, the syntax element nnpfc_purpose is designated as a reserved purpose.

[0227] 4. A method according to any one of solutions 1 to 3, wherein, when the chroma component block width (SubWidthC) is equal to 2 and the chroma component block height (SubHeightC) is equal to 1, nnpfc_purpose should be equal to a value that is neither 2 nor 4, or the NNPFC output chroma component block flag (nnpfc_out_sub_c_flag) should not be equal to 0.

[0228] 5. According to the method described in any one of solutions 1 to 4, when the chroma format identification code (ChromaFormatIdc) is equal to 2 and nnpfc_out_sub_c_flag is present, the value of nnpfc_out_sub_c_flag shall be equal to 1.

[0229] 6. A device for processing video data, comprising: a processor; and a non-transitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform a method according to any one of solutions 1 to 5.

[0230] 7. A non-transitory computer-readable medium, which includes a computer program product for use by a video codec device, the computer program product including computer executable instructions stored on the non-transitory computer-readable medium, so that when the computer executable instructions are executed by a processor, the video codec device performs a method according to any one of solutions 1 to 5.

[0231] 8. A non-transitory computer-readable recording medium storing a bitstream of a video, the bitstream of the video being generated by a method performed by a video processing device, wherein the method comprises: determining a value of a neural network post-processing filter characteristic (NNPFC) purpose syntax element nnpfc_purpose, wherein when the value is 0, the syntax element nnpfc_purpose is designated as a specific purpose or a reserved purpose; and generating a bitstream based on the determination.

[0232] 9. A method for storing a bit stream of a video, comprising:

[0233] Determine a value of a neural network post-processing filter characteristic (NNPFC) purpose syntax element nnpfc_purpose, wherein when the value is 0, the syntax element nnpfc_purpose is designated as a specific purpose or a reserved purpose; generate a bitstream based on the determination; and store the bitstream in a non-transitory computer-readable recording medium.

[0234] 10. The method, apparatus or system described in this document.

[0235] The following solutions illustrate further examples of the techniques discussed herein.

[0236] 1. A method for processing media data, comprising: determining a value of a neural network post-processing filter characteristic (NNPFC) output chroma component block flag (nnpfc_out_sub_c_flag) in a supplemental enhancement information (SEI) message of an NNPFC, wherein when a chroma format identification code (ChromaFormatIdc) is equal to 2 and nnpfc_out_sub_c_flag is present, the value of nnpfc_out_sub_c_flag should be equal to 1; and performing conversion between visual media data and a bitstream based on nnpfc_out_sub_c_flag.

[0237] 2. The method of solution 1, wherein nnpfc_out_sub_c_flag specifies the values ​​of output sub-picture width chroma (outSubWidthC) and output sub-picture height chroma (outSubHeightC).

[0238] 3. The method of solution 1 or 2, wherein nnpfc_out_sub_c_flag equal to 1 specifies outSubWidthC equal to 1 and outSubHeightC equal to 1.

[0239] 4. A method according to any of solutions 1 to 3, wherein nnpfc_out_sub_c_flag equal to 0 specifies outSubWidthC equal to 2 and outSubHeightC equal to 1.

[0240] 5. The method according to any one of solutions 1 to 4, wherein the NNPFC SEI message includes an NNPFC purpose syntax element nnpfc_purpose, and wherein, when the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose is designated as a specific purpose or a reserved purpose.

[0241] 6. A method according to any one of solutions 1 to 5, wherein when the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose indicates that visual quality improvement is provided by the corresponding neural network post-processing filter (NNPF).

[0242] 7. The method according to any one of solutions 1 to 6, wherein when the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose indicates that the reservation purpose is provided by the corresponding NNPF.

[0243] 8. A method according to any one of solutions 1 to 7, wherein when the sub-picture width chroma (SubWidthC) is equal to 2 and the sub-picture height chroma (SubHeightC) is equal to 1, nnpfc_purpose should be equal to a value that is neither 2 nor 4, or nnpfc_out_sub_c_flag should not be equal to 0.

[0244] 9. The method according to any one of solutions 1 to 8, wherein when nnpfc_purpose is equal to a value other than 0, 2, or 4, nnpfc_out_sub_c_flag does not exist or nnpfc_out_sub_c_flag is equal to 1.

[0245] 10. A non-transitory computer-readable recording medium storing a bitstream of a video, the bitstream of the video being generated by a method performed by a video processing device, wherein the method comprises: determining a value of a neural network post-processing filter characteristic (NNPFC) output chroma component block flag (nnpfc_out_sub_c_flag) in a supplemental enhancement information (SEI) message of an NNPFC, wherein when a chroma format identification code (ChromaFormatIdc) is equal to 2 and nnpfc_out_sub_c_flag is present, the value of nnpfc_out_sub_c_flag should be equal to 1; and generating a bitstream based on the determination.

[0246] 11. The non-transitory computer readable recording medium of solution 10, wherein nnpfc_out_sub_c_flag specifies values ​​of output sub-picture width chroma (outSubWidthC) and output sub-picture height chroma (outSubHeightC).

[0247] 12. The non-transitory computer-readable recording medium of solution 10 or 11, wherein nnpfc_out_sub_c_flag equal to 1 specifies that outSubWidthC equals 1 and outSubHeightC equals 1.

[0248] 13. The non-transitory computer-readable recording medium of any one of solutions 10 to 12, wherein nnpfc_out_sub_c_flag equal to 0 specifies that outSubWidthC is equal to 2 and outSubHeightC is equal to 1.

[0249] 14. The non-transitory computer-readable recording medium according to any one of solutions 10 to 13, wherein the NNPFC SEI message includes an NNPFC purpose syntax element nnpfc_purpose, and wherein, when a value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose is designated as a specific purpose or a reserved purpose.

[0250] 15. A non-transitory computer-readable recording medium according to any one of solutions 10 to 14, wherein, when the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose indicates that visual quality improvement is provided by the corresponding neural network post-processing filter (NNPF).

[0251] 16. The non-transitory computer-readable recording medium according to any one of solutions 10 to 15, wherein when the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose indicates that the reservation purpose is provided by the corresponding NNPF.

[0252] 17. A non-transitory computer-readable recording medium according to any one of solutions 10 to 16, wherein, when the sub-picture width chroma (SubWidthC) is equal to 2 and the sub-picture height chroma (SubHeightC) is equal to 1, nnpfc_purpose should be equal to a value that is neither 2 nor 4, or nnpfc_out_sub_c_flag should not be equal to 0.

[0253] 18. The non-transitory computer-readable recording medium according to any one of solutions 10 to 17, wherein when nnpfc_purpose is equal to a value other than 0, 2, or 4, nnpfc_out_sub_c_flag does not exist or nnpfc_out_sub_c_flag is equal to 1.

[0254] 19. A device for processing video data, comprising: a processor; and a non-transitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform a method according to any one of solutions 1 to 9.

[0255] 20. A non-transitory computer-readable medium, comprising a computer program product for use by a video codec device, the computer program product comprising computer executable instructions stored on the non-transitory computer-readable medium, so that when the computer executable instructions are executed by a processor, the video codec device performs a method according to any one of solutions 1 to 9.

[0256] 21. A method for storing a bitstream of a video, comprising: determining a value of a neural network post-processing filter characteristic (NNPFC) output chroma component block flag (nnpfc_out_sub_c_flag) in a supplemental enhancement information (SEI) message of an NNPFC, wherein when a chroma format identification code (ChromaFormatIdc) is equal to 2 and nnpfc_out_sub_c_flag exists, the value of nnpfc_out_sub_c_flag should be equal to 1; generating a bitstream based on the determination; and storing the bitstream in a non-temporary computer-readable recording medium.

[0257] In the solution described herein, an encoder may comply with the format rules by generating a codec representation according to the format rules. In the solution described herein, a decoder may parse the syntax elements in the codec representation using the format rules to generate decoded video, knowing the presence and absence of the syntax elements according to the format rules.

[0258] In this document, the term "video processing" may refer to video encoding, video decoding, video compression, or video decompression. For example, during the conversion from a pixel representation of a video to a corresponding bitstream representation, a video compression algorithm may be applied, and vice versa. As defined by the syntax, the bitstream representation of the current video block may correspond, for example, to bits that are juxtaposed or interspersed in different places within the bitstream. For example, macroblocks may be encoded according to error residual values ​​of transforms and codecs and also using bits in headers and other fields in the bitstream. In addition, during conversion, the decoder may parse the bitstream based on the determination, knowing that some fields may or may not be present, as described in the above solution. Similarly, the encoder may determine whether to include or not include certain syntax fields, and generate the codec representation accordingly by including or excluding syntax fields from the codec representation.

[0259] The disclosed and other solutions, examples, embodiments, modules and functional operations described in this document can be implemented in digital electronic circuits, or in computer software, firmware or hardware (including the structures disclosed in this document and their structural equivalents), or in a combination of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium, which are used to be executed by a data processing device or control the operation of the data processing device. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a combination of substances that affect machine-readable propagation signals, or a combination of one or more of them. The term "data processing device" includes all devices, equipment and machines for processing data, including, for example, a programmable processor, a computer, or multiple processors or computers. In addition to hardware, the device may also include code that creates an execution environment for the computer program in question, for example, 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 propagation signal is an artificially generated signal generated to encode information for transmission to a suitable receiver device, such as a machine-generated electrical signal, an optical signal, or an electromagnetic signal.

[0260] 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 may 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 storing one or more modules, subroutines, or code portions). A computer program may be deployed to execute on one computer or on multiple computers located at one site or distributed across multiple sites and interconnected by a communication network.

[0261] 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 special purpose logic circuits, and the apparatus can also be implemented as special purpose logic circuits, such as FPGAs (field programmable gate arrays) or ASICs (application specific integrated circuits).

[0262] Processors suitable for executing computer programs include, for example, general-purpose and special-purpose microprocessors, and any one or more processors of any type of digital computer. Typically, the processor will receive instructions and data from a read-only memory or a random access memory or both. The basic elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include one or more mass storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) for storing data, or operably coupled to receive data from or transfer data to or from the one or more mass storage devices. However, a computer does not require such a device. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, including, for example, semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and compact disk read-only memory (CD ROM) and digital versatile disk read-only memory (DVD-ROM) disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0263] Although this patent document contains many details, these details should not be interpreted as limitations on any subject matter or the scope of possible protection, but rather as descriptions of features of specific embodiments specified for specific technologies. Certain features described in the context of separate embodiments in this patent document may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although features may be described above as working in certain combinations and even initially claimed as such, one or more features from the claimed combination may be excluded from the combination in some cases, and the claimed combination may be directed to a sub-combination or a variation of the sub-combination.

[0264] Similarly, although operations are depicted in a particular order in the drawings, this should not be understood as requiring that such operations be performed in the particular order shown or in a sequential order, or that all of the operations shown be performed, to achieve the desired results. In addition, 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.

[0265] Only a few implementations and examples are described, and other implementations, enhancements, and variations may be made based on what is described and shown in this patent document.

[0266] A first component is directly coupled to a second component when there is no intermediate component between the first component and the second component other than a line, a trace, or another medium. A first component is indirectly coupled to a second component when there is an intermediate component between the first component and the second component other than a line, a trace, or another medium. The term "coupled" and its variations include direct coupling and indirect coupling. The use of the term "approximately" is meant to include a range of ±10% of the subsequent numerical value unless otherwise stated.

[0267] Although several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are considered to be illustrative rather than restrictive, and are not intended to be limited to the details given herein. For example, various elements or components may be combined or integrated in another system, or certain features may be omitted or not implemented.

[0268] In addition, without departing from the scope of the present disclosure, the techniques, systems, subsystems and methods described and illustrated as discrete or separate in various embodiments may be combined or integrated with other systems, modules, techniques or methods. Other items shown or discussed as coupled may be directly connected, or may be indirectly coupled or communicated through some interface, device or intermediate component, whether electrically, mechanically or otherwise. Other examples of changes, substitutions and modifications may be determined by those skilled in the art and may be made without departing from the spirit and scope of the present disclosure.

Claims

1. A method for processing media data, comprising: Determine the value of the NNPFC output chroma component block flag nnpfc_out_sub_c_flag in the neural network post-processing filter characteristic NNPFC supplemental enhancement information SEI message, wherein when the chroma format identification code ChromaFormatIdc is equal to 2 to indicate that the color format is 4:2:2 format, and the nnpfc_out_sub_c_flag exists, the value of the nnpfc_out_sub_c_flag should be equal to 1; and Conversion between visual media data and bitstream is performed based on the nnpfc_out_sub_c_flag.

2. The method according to claim 1, wherein: The nnpfc_out_sub_c_flag specifies the values ​​of the output sub-picture width chroma outSubWidthC and the output sub-picture height chroma outSubHeightC.

3. The method according to claim 1 or 2, wherein: The nnpfc_out_sub_c_flag equal to 1 specifies that outSubWidthC is equal to 1 and outSubHeightC is equal to 1.

4. The method according to any one of claims 1 to 3, wherein: The nnpfc_out_sub_c_flag equal to 0 specifies outSubWidthC equal to 2 and outSubHeightC equal to 1.

5. The method according to any one of claims 1 to 4, wherein: The NNPFC SEI message includes an NNPFC purpose syntax element nnpfc_purpose, and wherein, when a value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose is designated as a specific purpose or a reserved purpose.

6. The method according to any one of claims 1 to 5, wherein: When the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose indicates that visual quality improvement is provided by the corresponding neural network post-processing filter NNPF.

7. The method according to any one of claims 1 to 6, wherein: When the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose indicates that the reservation purpose is provided by the corresponding NNPF.

8. The method according to any one of claims 1 to 7, wherein: When the sub-picture width chroma SubWidthC is equal to 2 and the sub-picture height chroma SubHeightC is equal to 1, nnpfc_purpose shall be equal to a value neither 2 nor 4, or nnpfc_out_sub_c_flag shall not be equal to 0.

9. The method according to any one of claims 1 to 8, wherein: When nnpfc_purpose is equal to a value other than 0, 2, or 4, the nnpfc_out_sub_c_flag does not exist or the nnpfc_out_sub_c_flag is equal to 1.

10. A non-transitory computer-readable recording medium, wherein: The non-transitory computer-readable recording medium stores a bit stream of a video, the bit stream of the video being generated by a method performed by a video processing device, wherein the method comprises: Determine the value of the NNPFC output chroma component block flag nnpfc_out_sub_c_flag in the neural network post-processing filter characteristic NNPFC supplemental enhancement information SEI message, wherein when the chroma format identification code ChromaFormatIdc is equal to 2 and the nnpfc_out_sub_c_flag exists, the value of the nnpfc_out_sub_c_flag should be equal to 1; and A bitstream is generated based on the determination.

11. The non-transitory computer-readable recording medium according to claim 10, wherein: The nnpfc_out_sub_c_flag specifies the values ​​of the output sub-picture width chroma outSubWidthC and the output sub-picture height chroma outSubHeightC.

12. The non-transitory computer-readable recording medium according to claim 10 or 11, wherein: nnpfc_out_sub_c_flag equal to 1 specifies that outSubWidthC equal to 1 and outSubHeightC equal to 1.

13. The non-transitory computer-readable recording medium according to any one of claims 10 to 12, wherein: nnpfc_out_sub_c_flag equal to 0 specifies outSubWidthC equal to 2 and outSubHeightC equal to 1.

14. The non-transitory computer-readable recording medium according to any one of claims 10 to 13, wherein: The NNPFC SEI message includes an NNPFC purpose syntax element nnpfc_purpose, and wherein, when a value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose is designated as a specific purpose or a reserved purpose.

15. The non-transitory computer-readable recording medium according to any one of claims 10 to 14, wherein: When the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose indicates that visual quality improvement is provided by the corresponding neural network post-processing filter NNPF.

16. The non-transitory computer-readable recording medium according to any one of claims 10 to 15, wherein: When the value of the syntax element nnpfc_purpose is 0, the syntax element nnpfc_purpose indicates that the reservation purpose is provided by the corresponding NNPF.

17. The non-transitory computer-readable recording medium according to any one of claims 10 to 16, wherein: When the sub-picture width chroma SubWidthC is equal to 2 and the sub-picture height chroma SubHeightC is equal to 1, nnpfc_purpose shall be equal to a value neither 2 nor 4, or nnpfc_out_sub_c_flag shall not be equal to 0.

18. The non-transitory computer-readable recording medium according to any one of claims 10 to 17, wherein: When nnpfc_purpose is equal to a value other than 0, 2, or 4, the nnpfc_out_sub_c_flag does not exist or the nnpfc_out_sub_c_flag is equal to 1.

19. A device for processing video data, comprising: processor; and a non-transitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform the method according to any one of claims 1 to 9.

20. A non-transitory computer-readable medium, comprising a computer program product for use by a video codec device, the computer program product comprising computer executable instructions stored on the non-transitory computer-readable medium, such that when the computer executable instructions are executed by a processor, the video codec device performs the method according to any one of claims 1 to 9.

21. A method for storing a bit stream of a video, comprising: Determine a value of an NNPFC output chroma component block flag nnpfc_out_sub_c_flag in a neural network post-processing filter characteristic NNPFC supplemental enhancement information SEI message, wherein when the chroma format identification code ChromaFormatIdc is equal to 2 and the nnpfc_out_sub_c_flag exists, the value of the nnpfc_out_sub_c_flag should be equal to 1; generate a bitstream based on the determination; and The bit stream is stored in a non-transitory computer-readable recording medium.

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