Neural network post-processing filter repetition, update, and activation

Abstract

A mechanism for processing video data is disclosed. The mechanism includes determining a neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message. The NNPFC SEI message is applicable to a current decoded picture of a current layer and all subsequent decoded pictures in an output order until the end of a current coding and decoding layer video sequence (CLVS), or until but not included within the current CLVS after the current decoded picture in the output order, and associated with a subsequent NNPFC SEI message in the decoding order having an NNPFC base flag (nnpfcbaseflag) equal to 0 and a specific NNPFC identifier (nnpfcid) value within the current CLVS, is subject to the earlier one.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 438,168, filed on January 10, 2023, the teachings and disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] This patent document relates to generating, storing, and using digital audio and video media information in a 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 bandwidth demand for digital video usage is likely to continue to grow. Summary of the Invention

[0005] A first aspect relates to a method of processing video data, comprising: determining a neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message is applicable to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of a current codec layer video sequence (CLVS), or until but not including a decoded picture in the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a specific NNPFC identifier (nnpfc_id) value in the current CLVS, whichever is earlier; and performing conversion between visual media data and a bitstream based on the NNPFC SEI message.

[0006] A second aspect relates to an apparatus 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 any one of the above aspects.

[0007] The third aspect relates to a non-transitory computer-readable medium, comprising a computer program product for use with a video codec device, the computer program product comprising computer-executable instructions stored on the non-transitory computer-readable medium, which, when executed by a processor, enables the video codec device to perform a method of any one of the above aspects.

[0008] A fourth aspect relates to a non-transitory computer-readable recording medium storing a bitstream of a video generated by a method performed by a video processing device, wherein the method includes: determining a neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message is applicable to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of a current codec layer video sequence (CLVS), or until but not including a decoded picture in the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a specific NNPFC identifier (nnpfc_id) value in the current CLVS, whichever is earlier.

[0009] A fifth aspect relates to a method for storing a bitstream of a video, comprising: determining a neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message is applicable to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of a current codec layer video sequence (CLVS), or until but not including a decoded picture in the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a specific NNPFC identifier (nnpfc_id) value in the current CLVS, whichever is earlier; generating a bitstream based on the determination; and storing the bitstream in a non-transitory computer-readable recording medium.

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

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

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

[0013] Figure 1 An example of deriving a luminance channel from a luma component is shown;

[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 apparatus;

[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 encoding and decoding system;

[0018] Figure 6 is a block diagram illustrating an example encoder;

[0019] Figure 7 is a block diagram illustrating an example decoder;

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

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

[0022] It should be understood at the outset 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 in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims and their full scope of equivalents.

[0023] The section headings used in this document are for ease of understanding and do not limit the applicability of the techniques and embodiments disclosed in each section to that section. In addition, the use of H.266 terminology 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 relative to the Versatile Video Codec (VVC) specification are shown above the text by bold italics (indicating deleted text) and bold (indicating added text).

[0024] 1. Preliminary Discussion

[0025] This document relates to image / video codec technology. Specifically, the disclosure relates to specifications for repetition, updating, and activation of neural network post-processing filters (NNPFs). The concepts can be applied, alone or in various combinations, to video bitstreams encoded or decoded by any codec, such as the Versatile Video Codec (VVC) standard and / or the Versatile Supplemental Enhancement Information (SEI) message (VSEI) standard for encoding and decoding video bitstreams.

[0026] 2. Abbreviation

[0027] Adaptation Parameter Set (APS), Access Unit (AU), Codec Video Sequence (CLVS), Codec Video Sequence Start (CLVSS), Cyclic Redundancy Check (CRC), Codec Video Sequence (CVS), Finite Impulse Response (FIR), Intra-frame Random Access Point (IRAP), Network Abstraction Layer (NAL), Picture Parameter Set (PPS), Picture Unit (PU), Random Access Skip Leading (RASL) Picture, Supplemental Enhancement Information (SEI), Step-by-Step Temporal Sublayer Access (STSA), Video Codec Layer (VCL), Versatile Supplemental Enhancement Information (VSEI) as described in ITU-T Rec. H.274 | ISO / IEC 23002-7, Video Usability Information (VUI), Versatile Video Codec (VVC) as described in ITU-T Rec. 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 within 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 Vision, 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) standard [1]. Starting with H.262, video codec standards are based on a hybrid video codec structure that utilizes temporal prediction plus transform coding. To explore video codec technologies beyond High Efficiency Video Coding (HEVC), the Video Coding Experts Group (VCEG) and the Moving Picture Experts Group (MPEG) established the Joint Video Exploration Team (JVET). Furthermore, JVET adopted some 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] and the associated Versatile Supplementary Enhancement Information (VSEI) standard for codec video bitstreams (ITU-T H.274 | ISO / IEC 23002-7) [4] are designed for the widest range of applications, including simple uses such as television broadcasting, video conferencing, or playback from storage media, as well as 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 Codec (EVC) standard (ISO / IEC 23094-1) is another video codec standard being developed by MPEG.

[0033] 3.2 SEI messages in general and in VVC and VSEI

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

[0035] Annex D of VVC specifies the syntax and semantics of the SEI message payloads 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] WG 05 output documents N0158 [5] and JVET-AB2006 [6] include specifications for 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] The Neural Network Post-Processing Filter Characteristics (NNPFC) 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] Using this SEI message requires defining the following variables:

[0046] – The width and height of the cropped decoded output picture, in units of luma samples, denoted as CroppedWidth and CroppedHeight in this document.

[0047] – The luma sample array CroppedYPic[idx] and the chroma sample arrays CroppedCbPic[idx] and CroppedCrPic[idx] (when present) of the cropped decoded output picture, where idx ranges from 0 to numInputPics-1 (inclusive), which are used as input to the post-processing filters.

[0048] – Bit depth BitDepthY of the luma sample array for the cropped decoded output picture.

[0049] – The bit depth BitDepthC of the chroma sample array (if any) for the cropped decoded output picture.

[0050] – a chroma format indicator, denoted herein as ChromaFormatIdc, as described in subclause 7.3.

[0051] – When nnpfc_auxiliary_inp_idc is equal to 1, the filter strength control value StrengthControlVal shall be a real number in the range 0 to 1 (inclusive).

[0052] The variables SubWidthC and SubHeightC are derived from ChromaFormatIdc as specified in Table 2. NOTE 1 – More than one NNPFC SEI message may be present for the same picture. When more than one NNPFC SEI message with different values of nnpfc_id is present or activated for the same picture, they may have the same or different values of nnpfc_purpose and nnpfc_mode_idc.

[0053] nnpfc_id contains an identification number that can be used to identify the post-processing filter. The value of nnpfc_id shall be in the range of 0 to 232-2 (inclusive). The values of nnpfc_id are from 256 to 511 (inclusive), and the values from 231 to 232-2 (inclusive) are reserved for future use by ITU-T | ISO / IEC. Decoders conforming to this version of this document that encounter an NNPFC SEI message with a nnpfc_id in the range of 256 to 511 (inclusive) or in the range of 231 to 232-2 (inclusive) shall ignore the SEI message.

[0054] When the NNPFC SEI message is the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, the following applies:

[0055] – This SEI message specifies the base post-processing filters.

[0056] – This SEI message applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS.

[0057] When an NNPFC SEI message is a repetition of a previous NNPFC SEI message in decoding order in the current CLVS, subsequent semantics apply as if the SEI message was the only NNPFC SEI message with the same content within the current CLVS.

[0058] When the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, the following applies:

[0059] – This SEI message defines the update relative to the preceding base post-processing filter in decoding order with the same nnpfc_id value.

[0060] – This SEI message applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS, or until the next NNPFC SEI message in output order with this specific nnpfc_id value within the current CLVS.

[0061] nnpfc_mode_idc equal to 0 indicates that the SEI message contains an ISO / IEC 15938-17 bitstream that specifies a base post-processing filter or an update relative to a base post-processing filter with the same nnpfc_id value.

[0062] When the NNPFC SEI message is the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, nnpfc_mode_idc equal to 1 specifies that the base post-processing filter associated with the nnpfc_id value is a neural network identified by the URI indicated by nnpfc_uri (having the format identified by the tag URI nnpfc_tag_uri).

[0063] When the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, nnpfc_mode_idc equal to 1 specifies that updates relative to the base post-processing filter with the same nnpfc_id value are defined by the URI indicated by nnpfc_uri (with a format identified by the tag URI nnpfc_tag_uri).

[0064] In bitstreams conforming to this version of this document, the value of nnpfc_mode_idc shall be in the range of 0 to 1, inclusive. Values of nnpfc_mode_idc from 2 to 255, inclusive, are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this document. Decoders conforming to this version of this document shall ignore NNPFC SEI messages with nnpfc_mode_idc in the range of 2 to 255, inclusive. Values of nnpfc_mode_idc greater than 255 shall not be present in bitstreams conforming to this version of this document and are not reserved for future use.

[0065] When this SEI message is the first NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS, the post-processing filter PostProcessingFilter() is assigned to be the same as the base post-processing filter.

[0066] When this SEI message is not the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, the post-processing filter PostProcessingFilter() is obtained by applying the updates defined by this SEI message to the base post-processing filter.

[0067] Updates are not cumulative, but each update is applied to the base post-processing filter, which is the post-processing filter specified by the first NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS.

[0068] nnpfc_reserved_zero_bit_a shall be equal to 0 in bitstreams conforming to this version of this document. Decoders shall ignore NNPFC SEI messages with nnpfc_reserved_zero_bit_a not equal to 0.

[0069] nnpfc_tag_uri contains a tag uniform resource identifier (URI) with syntax and semantics as specified by Internet Engineering Task Force (IETF) Request for Comments (RFC) 4151, used to identify the format and related information of a neural network used as a base post-processing filter or an update relative to the base post-processing filter specified by nnpfc_uri with the same nnpfc_id value.

[0070] NOTE 2 – nnpfc_tag_uri is able to uniquely identify the format of neural network data specified by nnrpf_uri without the need for a central registration authority.

[0071] nnpfc_tag_uri equal to "tag:iso.org,2023:15938-17" indicates that the neural network data identified by nnpfc_uri complies with ISO / IEC 15938-17.

[0072] nnpfc_uri contains a URI with syntax and semantics as specified by IETF Internet Standard 66 that identifies a neural network used as a base post-processing filter or an update relative to a base post-processing filter with the same nnpfc_id value.

[0073] nnpfc_formatting_and_purpose_flag equal to 1 specifies that syntax elements related to filter purpose, input format, output format, and complexity are present. This flag is also referred to as a flag indicating the presence of NNPFC attribute parameters. nnpfc_formatting_and_purpose_flag equal to 0 specifies that syntax elements related to filter purpose, input format, output format, and complexity are not present.

[0074] When this SEI message is the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, nnpfc_formatting_and_purpose_flag shall be equal to 1. When this SEI message is not the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, nnpfc_formatting_and_purpose_flag shall be equal to 0.

[0075] nnpfc_purpose indicates the purpose of the post-processing filter, as specified in Table 20.

[0076] In bitstreams conforming to this version of this document, the value of nnpfc_purpose shall be in the range of 0 to 5, inclusive. Values of nnpfc_purpose from 6 to 1023, inclusive, are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this document. Decoders conforming to this version of this document shall ignore NNPFC SEI messages with nnpfc_purpose in the range of 6 to 1203, inclusive. Values of nnpfc_purpose greater than 1023 shall not be present in bitstreams conforming to this version of this document and are not reserved for future use.

[0077] Table 20 - Definition of nnpfc_purpose

[0078]

[0079]

[0080] NOTE 3 – 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 the following syntax elements whose presence is conditional on nnpfc_purpose being equal to this value.

[0081] When SubWidthC is equal to 1 and SubHeightC is equal to 1, nnpfc_purpose should not be equal to 2 or 4.

[0082] 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 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.

[0083] nnpfc_pic_width_in_luma_samples and nnpfc_pic_height_in_luma_samples specify the width and height, respectively, of the luma sample array of the picture resulting from 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. The value of nnpfc_pic_width_in_luma_samples shall be in the range of CroppedWidth to CroppedWidth*16-1 (inclusive). The value of nnpfc_pic_height_in_luma_samples shall be in the range of CroppedHeight to CroppedHeight*16-1 (inclusive).

[0084] nnpfc_num_input_pics_minus2 plus 2 specifies the number of decoded output pictures used as input to the post-processing filter.

[0085] nnpfc_interpolated_pics[i] specifies the number of interpolated pictures generated by the post-processing filter between the i-th picture and the (i+1)-th picture used as input to the post-processing filter.

[0086] The variable numInputPics specifying the number of pictures used as input to the post-processing filter and the variable numOutputPics specifying the total number of pictures generated by the post-processing filter are derived as follows:

[0087]

[0088] nnpfc_component_last_flag is equal to 1 to indicate that the last dimension in the input tensor inputTensor of the post-processing filter and the output tensor outputTensor produced by the post-processing filter is used for the current channel. nnpfc_component_last_flag is equal to 0 to indicate that the third dimension in the input tensor inputTensor of the post-processing filter and the output tensor outputTensor produced by the post-processing filter is used for the current channel.

[0089] NOTE 4 – The first dimension in the input and output tensors is used for batch indexing, which is a practice in some neural network frameworks. Although the formulas in the semantics of this SEI message use a batch size corresponding to a batch index equal to 0, it is up to the post-processing implementation to determine the batch size used as input to the neural network inference.

[0090] Note 5 – For example, when nnpfc_inp_order_idc is equal to 3 and nnpfc_auxiliary_inp_idc is equal to 1, there are 7 channels in the input tensor, including four luma matrices, two chroma matrices, and one auxiliary input matrix. In this case, the procedure DeriveInputTensors() will derive each of these 7 channels of the input tensor one by one, and when a particular channel of these channels is processed, that channel is called the current channel during the procedure.

[0091] nnpfc_inp_format_idc indicates a method for converting the sample values of the cropped decoded output picture into the input values of the post-processing filter. When nnpfc_inp_format_idc 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:

[0092] InpY( x ) = x ÷ ( ( 1 << BitDepthY ) - 1 ) (77)

[0093] InpC( x )= x ÷ ( ( 1 << BitDepthC ) - 1 ) (78)

[0094] When nnpfc_inp_format_idc 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:

[0095]

[0096] The variable inpTensorBitDepth is derived from the syntax element nnpfc_inp_tensor_bitdepth_minus8 specified as follows.

[0097] Values of nnpfc_inp_format_idc greater than 1 are reserved for future specification by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this document. Decoders conforming to this version of this document shall ignore NNPFC SEI messages containing reserved values of nnpfc_inp_format_idc.

[0098] nnpfc_inp_tensor_bitdepth_minus8 specifies the bit depth of the luma sample values in the input integer tensor plus 8. The value of inpTensorBitDepth is derived as follows:

[0099] inpTensorBitDepth = nnpfc_inp_tensor_bitdepth_minus8 + 8 (81)

[0100] A bitstream conformance requirement is that the value of nnpfc_inp_tensor_bitdepth_minus8 must be in the range 0 to 24 (inclusive).

[0101] nnpfc_inp_order_idc indicates a method of ordering the sample array of the cropped decoded output picture as one of the input pictures of the post-processing filter.

[0102] In bitstreams conforming to this version of this document, the value of nnpfc_inp_order_idc shall be in the range of 0 to 3 (inclusive). Values of nnpfc_inp_order_idc from 4 to 255 (inclusive) are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this document. Decoders conforming to this version of this document shall ignore NNPFC SEI messages with nnpfc_inp_order_idc in the range of 4 to 255 (inclusive). Values of nnpfc_inp_order_idc greater than 255 shall not be present in bitstreams conforming to this version of this document and are not reserved for future use.

[0103] When ChromaFormatIdc is not equal to 1, nnpfc_inp_order_idc shall not be equal to 3.

[0104] Table 21 contains the informative description of the nnpfc_inp_order_idc values.

[0105] Table 21 - Description of nnpfc_inp_order_idc values

[0106]

[0107] Figure 1 An example of deriving the luma channel from the luma component is shown, for example when nnpfc_inp_order_idc is equal to 3.

[0108] A tile is a rectangular array of samples of a component (eg, luma or chroma components) from a picture.

[0109] nnpfc_auxiliary_inp_idc greater than 0 indicates 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 auxiliary input data is derived, as specified in Equation 82.

[0110] In bitstreams conforming to this version of this document, the value of nnpfc_auxiliary_inp_idc shall be in the range of 0 to 1, inclusive. Values of nnpfc_inp_order_idc from 2 to 255, inclusive, are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this document. Decoders conforming to this version of this document shall ignore NNPFC SEI messages with nnpfc_inp_order_idc in the range of 2 to 255, inclusive. Values of nnpfc_inp_order_idc greater than 255 shall not be present in bitstreams conforming to this version of this document and are not reserved for future use.

[0111] The procedure DeriveInputTensors() for deriving the input tensor inputTensor for a given vertical sample coordinate cTop and horizontal sample coordinate cLeft of the top left sample position of a tile of samples included in the specified input tensor is specified as follows:

[0112]

[0113]

[0114]

[0115]

[0116] 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 filter is specified in the SEI message syntax structure. nnpfc_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 filter is the same as the combination indicated in the VUI parameters of the CLVS.

[0117] nnpfc_colour_primaries has the same semantics as specified in subclause 7.3 for the vui_colour_primaries syntax element, except as follows:

[0118] –nnpfc_colour_primaries specifies the color primaries of the picture resulting from applying the neural network post-processing filters specified in the SEI message, instead of the color primaries used for CLVS.

[0119] – When nnpfc_colour_primaries is not present in the NNPFC SEI message, the value of nnpfc_colour_primaries is inferred to be equal to vui_colour_primaries.

[0120] nnpfc_transfer_characteristics has the same semantics as specified in subclause 7.3 for the vui_transfer_characteristics syntax element, except as follows:

[0121] –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.

[0122] – When nnpfc_transfer_characteristics is not present in the NNPFC SEI message, the value of nnpfc_transfer_characteristics is inferred to be equal to vui_transfer_characteristics.

[0123] nnpfc_matrix_coeffs has the same semantics as specified in subclause 7.3 for the vui_matrix_coeffs syntax element, except as follows:

[0124] –nnpfc_matrix_coeffs specifies the matrix coefficients for the picture resulting from applying the neural network post-processing filters specified in the SEI message, instead of the matrix coefficients used for CLVS.

[0125] – When nnpfc_matrix_coeffs is not present in the NNPFC SEI message, the value of nnpfc_matrix_coeffs is inferred to be equal to vui_matrix_coeffs.

[0126] – The allowed values of nnpfc_matrix_coeffs are not constrained by the chroma format of the decoded video picture indicated by the value of ChromaFormatIdc in the semantics of the VUI parameters.

[0127] – When nnpfc_matrix_coeffs equals 0, nnpfc_out_order_idc shall not equal 1 or 3.

[0128] nnpfc_out_format_idc equal to 0 indicates that the sample values output by the post - processing filter are real numbers, where the value range from 0 to 1 (including the end values) is linearly mapped to the unsigned integer value range from 0 to (1 << bitDepth) – 1 (including the end values) for any desired bit depth bitDepth for subsequent post - processing or display.

[0129] nnpfc_out_format_flag equal to 1 indicates that the sample values output by the post - processing filter are unsigned integers within the range from 0 to (1 << (nnpfc_out_tensor_bitdepth_minus8 + 8)) - 1 (including the end values).

[0130] Values of nnpfc_out_format_idc greater than 1 are reserved for future ITU - T|ISO / IEC specification and shall not be present in the bitstream compliant with this version of this document. Decoders compliant with this version of this document shall ignore NNPFC SEI messages containing reserved values of nnpfc_out_format_idc.

[0131] nnpfc_out_tensor_bitdepth_minus8 plus 8 specifies the bit depth of the sample values in the output integer tensor. The value of nnpfc_out_tensor_bitdepth_minus8 shall be within the range from 0 to 24 (including the end values).

[0132] nnpfc_out_order_idc indicates the output order of the samples produced by the post - processing filter.

[0133] In bitstreams conforming to this version of this document, the value of nnpfc_out_order_idc shall be in the range of 0 to 3, inclusive. Values of nnpfc_out_order_idc from 4 to 255, inclusive, are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this document. Decoders conforming to this version of this document shall ignore NNPFC SEI messages with nnpfc_out_order_idc in the range of 4 to 255, inclusive. Values of nnpfc_out_order_idc greater than 255 shall not be present in bitstreams conforming to this version of this document and are not reserved for future use.

[0134] When nnpfc_purpose is equal to 2 or 4, nnpfc_out_order_idc should not be equal to 3.

[0135] Table 22 contains an informative description of the nnpfc_out_order_idc values.

[0136] Table 22 - Description of nnpfc_out_order_idc values

[0137]

[0138] The procedure StoreOutputTensors() for deriving the sample values in the filtered output sample arrays FilteredYPic, FilteredCbPic, and FilteredCrPic from the output tensor outputTensor given vertical sample coordinates cTop and horizontal sample coordinates cLeft for the top left sample position of a tile of samples included in the specified input tensor is specified as follows:

[0139]

[0140]

[0141]

[0142] nnpfc_constant_patch_size_flag equal to 1 indicates that the post-processing filter accepts as input the exact patch size indicated by nnpfc_patch_width_minus1 and nnpfc_patch_height_minus1. nnpfc_constant_patch_size_flag equal to 0 indicates that the post-processing filter accepts as input any patch size that is a positive integer multiple of the patch size indicated by nnpfc_patch_width_minus1 and nnpfc_patch_height_minus1.

[0143] nnpfc_patch_width_minus1+1 indicates the horizontal sample count of the required patch size as input to the post-processing filter when nnpfc_constant_patch_size_flag is equal to 1. The value of nnpfc_patch_width_minus1 shall be in the range of 0 to Min(32766, CroppedWidth-1), inclusive.

[0144] nnpfc_patch_height_minus1+1 indicates the vertical sample count of the patch size required for input to the post-processing filter when nnpfc_constant_patch_size_flag is equal to 1. The value of nnpfc_patch_height_minus1 shall be in the range of 0 to Min(32766, CroppedHeight-1), inclusive.

[0145] Let the variables inpPatchWidth and inpPatchHeight be the width and height of the patch size respectively.

[0146] If nnpfc_constant_patch_size_flag is equal to 0, the following applies:

[0147] – The values of inpPatchWidth and inpPatchHeight are provided by external methods not specified in this document, or are set by the post-process itself.

[0148] –inpPatchWidth must be a positive integer multiple of nnpfc_patch_width_minus1+1 and must be less than or equal to CroppedWidth. inpPatchHeight must be a positive integer multiple of nnpfc_patch_height_minus1+1 and must be less than or equal to CroppedHeight.

[0149] Otherwise (nnpfc_constant_patch_size_flag is equal to 1), the value of inpPatchWidth is set equal to nnpfc_patch_width_minus1+1, and the value of inpPatchHeight is set equal to nnpfc_patch_height_minus1+1.

[0150] nnpfc_overlap indicates the horizontal and vertical sample counts of overlap of adjacent input tensors to the post-processing filter. The value of nnpfc_overlap must be in the range of 0 to 16383 (inclusive).

[0151] The variables outPatchWidth, outPatchHeight, horCScaling, verCScaling, outPatchCWidth, outPatchCHeight, and overlapSize are derived as follows:

[0152] outPatchWidth = ( nnpfc_pic_width_in_luma_samples * inpPatchWidth ) / CroppedWidth (84)

[0153] outPatchHeight=(nnpfc_pic_height_in_luma_samples*inpPatchHeight) / CroppedHeight(85)

[0154] horCScaling = SubWidthC / outSubWidthC (86)

[0155] verCScaling = SubHeightC / outSubHeightC (87)

[0156] outPatchCWidth = outPatchWidth * horCScaling (88)

[0157] outPatchCHeight = outPatchHeight * verCScaling (89)

[0158] overlapSize = nnpfc_overlap (90)

[0159] The bitstream conformance requirement 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.

[0160] nnpfc_padding_type indicates the padding process when referring to sample positions outside the boundaries of the cropped decoded output picture, as described in Table 23. The value of nnpfc_padding_type shall be in the range of 0 to 15 (inclusive).

[0161] Table 23 - Informative description of nnpfc_padding_type values

[0162] nnpfc_padding_type describe 0 Zero padding 1 Copy Fill 2 Reflection Fill 3 Surround Fill 4 Fixed padding 5..15 reserve

[0163] nnpfc_luma_padding_val indicates the luma value to be used for padding when nnpfc_padding_type is equal to 4.

[0164] nnpfc_cb_padding_val indicates the Cb value to be used for padding when nnpfc_padding_type is equal to 4.

[0165] nnpfc_cr_padding_val indicates the Cr value to be used for padding when nnpfc_padding_type is equal to 4.

[0166] The function InpSampleVal(y,x,picHeight,picWidth,croppedPic) whose input is the vertical sample position y, the horizontal sample position x, the picture height picHeight, the picture width picWidth and the sample array croppedPic returns the value of sampleVal derived as follows:

[0167] NOTE 6 – For the input to the function InpSampleVal(), the vertical positions are listed before the horizontal positions to be compatible with the input tensor convention of some inference engines.

[0168]

[0169]

[0170] The following example process may be used to filter the cropped decoded output picture on a tile-by-tile basis using a post-processing filter PostProcessingFilter() to generate a filtered picture containing Y, Cb, and Cr sample arrays FilteredYPic, FilteredCbPic, and FilteredCrPic, respectively, as indicated by nnpfc_out_order_idc.

[0171]

[0172] nnpfc_complexity_info_present_flag equal to 1 specifies that one or more syntax elements indicating the complexity of the post-processing filter associated with nnpfc_id are present. nnpfc_complexity_info_present_flag equal to 0 specifies that no syntax elements indicating the complexity of the post-processing filter associated with nnpfc_id are present.

[0173] 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 for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this document. Decoders conforming to this version of this document shall ignore NNPFC SEI messages with nnpfc_parameter_type_idc equal to 3.

[0174] nnpfc_log2_parameter_bit_length_minus3 equal to 0, 1, 2, and 3 respectively indicates that the neural network does not use parameters with bit lengths greater than 8, 16, 32, and 64. 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 bit lengths greater than 1.

[0175] nnpfc_num_parameters_idc indicates the maximum number of neural network parameters for the post-processing filter, in powers of 2048. nnpfc_num_parameters_idc equal to 0 indicates that the maximum number of neural network parameters is unknown. nnpfc_num_parameters_idc values shall be in the range of 0 to 52, inclusive. nnpfc_num_parameters_idc values greater than 52 are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this document. Decoders conforming to this version of this document shall ignore NNPFC SEI messages with nnpfc_num_parameters_idc greater than 52.

[0176] If the value of nnpfc_num_parameters_idc is greater than 0, the variable maxNumParameters is derived as follows:

[0177] maxNumParameters = (2048 << nnpfc_num_parameters_idc) – 1 (93)

[0178] It is a bitstream conformance requirement that the number of neural network parameters of the post-processing filters be less than or equal to maxNumParameters.

[0179] nnpfc_num_kmac_operations_idc greater than 0 indicates 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 unknown. The value of nnpfc_num_kmac_operations_idc shall be between 0 and 2. 32 The range is -1 (including the end value).

[0180] nnpfc_total_kilobyte_size is greater than 0 to indicate the total size in kilobytes required to store the uncompressed parameters of the neural network. The total size in bits is the number of bits equal to or greater than the sum of the bits used to store each parameter. nnpfc_total_kilobyte_size is the total size in bits divided by 8000, rounded up. nnpfc_total_kilobyte_size is equal to 0 to indicate that the total size required to store the parameters of the neural network is unknown. The value of nnpfc_total_kilobyte_size must be between 0 and 2.32 The range is -1 (including the end value).

[0181] nnpfc_reserved_zero_bit_b shall be equal to 0 in bitstreams conforming to this version of this document. Decoders shall ignore NNPFC SEI messages with nnpfc_reserved_zero_bit_b not equal to 0.

[0182] 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 present values of i shall be a complete bitstream conforming to ISO / IEC 15938-17.

[0183] 8.29 Neural Network Post-Processing Filter Activation SEI Message

[0184] 8.29.1 Neural Network Post-Processing Filter Activation SEI Message Syntax

[0185]

[0186] 8.29.2 Neural Network Post-Processing Filter Activation SEI Message Semantics

[0187] The Neural Network Post-Processing Filter Activation (NNPFA) SEI message activates or deactivates the possible use of the target neural network post-processing filter identified by nnpfa_target_id for post-processing filtering of a set of pictures.

[0188] NOTE 1 – Multiple NNPFA SEI messages may exist for the same picture, for example when post-processing filters are used for different purposes or filter different color components.

[0189] nnpfa_target_id indicates the target neural network post-processing filter, which is specified by one or more neural network post-processing filter characteristics SEI messages related to the current picture and with nnpfc_id equal to nnfpa_target_id.

[0190] The value of nnpfa_target_id must be between 0 and 2 32 -2 (inclusive). The value of nnpfa_target_id is from 256 to 511 (inclusive), and from 2 31 to 2 32 -2 (inclusive) are reserved for future use by ITU-T|ISO / IEC. A decoder conforming to this version of this document shall encounter a nnpfa_target_id in the range 256 to 511 (inclusive) or in the range 256 to 511 (inclusive).31 to 2 32 When an NNPFA SEI message is received in the range of -2 (inclusive), the SEI message shall be ignored.

[0191] An NNPFA SEI message with a specific value of nnpfa_target_id shall not be present in the current PU unless one or both of the following conditions are true:

[0192] - Within the current CLVS, there is an NNPFC SEI message having a specific value of nnpfc_id equal to the nnpfa_target_id present in the PU preceding the current PU in decoding order.

[0193] – There is an NNPFC SEI message with nnpfc_id equal to a specific value of nnpfa_target_id in the current PU.

[0194] When a PU includes both an NNPFC SEI message with a specific value of nnpfc_id and an NNPFA SEI message with nnpfa_target_id equal to the specific value of nnpfc_id, the NNPFC SEI message shall precede the NNPFA SEI message in decoding order.

[0195] nnpfa_cancel_flag equal to 1 indicates that the persistence of the target neural network post-processing filter established by any previous NNPFA SEI message with the same nnpfa_target_id as the current SEI message is canceled, i.e., the target neural network post-processing filter is no longer used unless it is activated by another NNPFA SEI message with the same nnpfa_target_id as the current SEI message and nnpfa_cancel_flag equal to 0. nnpfa_cancel_flag equal to 0 indicates that nnpfa_persistence_flag follows.

[0196] nnpfa_persistence_flag specifies the persistence of the target neural network post-processing filters of the current layer.

[0197] nnpfa_persistence_flag equal to 0 specifies that the target neural network post-processing filter can only be used for post-processing filtering of the current image.

[0198] nnpfa_persistence_flag equal to 1 specifies that the target neural network post-processing filters can be used for post-processing filtering of the current picture and all subsequent pictures of the current layer in output order until one or more of the following conditions are true:

[0199] – A new CLVS starts for the current layer.

[0200] – End of bitstream.

[0201] – Output the current layer with the same nnpfa_target_id and nnpfa_cancel_flag as the current SEI message

[0202] The picture associated with the NNPFA SEI message with NNPFA equal to 1 that follows the current picture in output order.

[0203] NOTE 2 – The target neural network post-processing filter is not applied to this subsequent picture in the current layer that is associated with an NNPFA SEI message with the same nnpfa_target_id as the current SEI message and nnpfa_cancel_flag equal to 1.

[0204] 4. Technical problems solved by the disclosed technical solution

[0205] The example designs for the Neural Network Post-Processing Filter Characteristics (NNPFC) SEI message and the Neural Network Post-Processing Filter Activation (NNPFA) SEI message have the following issues:

[0206] First, it is not explicitly specified when an NNPFC SEI message is a repetition of a previous NNPFC SEI message. It can be considered obvious that when an NNPFC SEI message nnpfcE has the same SEI payload content as the previous NNPFC SEI message nnpfcA in decoding order, nnpfcE is a repetition of nnpfcA. However, it is not that simple. For example, if there are five NNPFC SEI messages in decoding order, nnpfcA, nnpfcB, nnpfcC, nnpfcD, and nnpfcE, and nnpfcA, nnpfcB, nnpfcC, and nnpfcE have the same SEI payload content, but nnpfcD has a different SEI payload content from the other messages. In this case, nnpfcA is actually the previous NNPFC SEI message in decoding order relative to nnpfcE, and nnpfcE has the same SEI payload content as nnpfcA, but nnpfcE is an update to nnpfcD, and nnpfcD is an update to nnpfcC. Simply calling nnpfcE a repetition of nnfpcA and using this repetition in VSEI text would be problematic.

[0207] Second, the condition for updating the base NNPF is specified as follows: “when the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS.” However, the condition should be changed to: “when the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS and is not a duplicate of another NNPFC SEI message with the same nnpfc_id value within the current CLVS.”

[0208] Third, specify that the NNPFC SEI message specifying an update to the base NNPF applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS or the next NNPFC SEI message in output order with that specific nnpfc_id value within the current CLVS. Here, the second instance of "in output order" is used to describe the SEI message. However, "in output order" should only be used for pictures, not for SEI messages.

[0209] Fourth, it is specified that when an NNPFC SEI message is not the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, nnpfc_formatting_and_purpose_flag shall be equal to 0. However, a repetition of an NNPFC SEI message that is not the first NNPFC SEI message with the same nnpfc_id value within the CLVS, but that has nnpfc_formatting_and_purpose_flag equal to 1. Furthermore, an NNPFC SEI message with a particular nnpfc_id value within the CLVS may provide a full update of the NNPF specified by a previous NNPFC SEI message with the same nnpfc_id value within the CLVS, and such a full-update NNPFC SEI message will also have nnpfc_formatting_and_purpose_flag equal to 1.

[0210] Fifth, the NNPFA SEI message activates or deactivates the possible use of the target neural network post-processing filter (NNPF) identified by nnpfa_target_id for post-processing filtering of a set of pictures. However, there may be multiple NNPFC SEI messages with nnpfc_id equal to nnpfa_target_id before the NNPFASEI message in decoding order, and among these NNPFC SEI messages there may be an NNPFC SEI message specifying a base NNPF, followed by another NNPFC SEI message specifying an update of the base NNPF. In this case, it is unclear whether the base NNPF or the updated NNPF will be activated or deactivated by the NNPFA SEI message.

[0211] Sixth, specify that the NNPFC SEI message that specifies the base NNPF applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS. Specify that the NNPFC SEI message that specifies an update to the base NNPF applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS, or until the next NNPFC SEI message in output order with the specific nnpfc_id value within the current CLVS. Therefore, the NNPFA SEI message can activate the target NNPF for pictures that are not in the target picture set to which the NNPFC SEI message that specifies the target NNPF applies.

[0212] 5. List of solutions and implementation examples

[0213] In order to solve the above-described problems, the following methods are disclosed. These aspects should be considered as examples to explain general concepts and should not be interpreted in a narrow sense. In addition, these examples can be applied alone or in any combination.

[0214] 1) To solve Problem 1, it is specified that when an NNPFC SEI message nnpfcB has the same SEI payload content as a previous NNPFC SEI message nnpfcA in decoding order, nnpfcB is called a repetition of nnpfcA.

[0215] a. Furthermore, when an NNPFC SEI message nnpfcE is a repetition of another NNPFC SEI message nnpfcD, and at the same time nnpfcD is a repetition of yet another NNPFC SEI message nnpfcC, nnpfcE is also referred to as a repetition of nnpfcC.

[0216] 2) To address issue 2, the condition specifying the update of the base NNPF is changed as follows: “When the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS, and is not a repetition of another NNPFC SEI message with the same nnpfc_id value within the current CLVS”.

[0217] 3) To address issue 3, specify that: an NNPFC SEI message specifying an update to the base NNPF applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS, or until the next NNPFC SEI message in decoding order with that specific nnpfc_id value within the current CLVS.

[0218] 4) To address question 4, specify one or more of the following:

[0219] a. When the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS, nnpfc_formatting_and_purpose_flag is allowed to be equal to 0 or 1.

[0220] b. An NNPFC SEI message nnpfcA with a specific nnpfc_id value within the CLVS is allowed to provide an update to the NNPF specified by a previous NNPFC SEI message with the same nnpfc_id value within the CLVS, where nnpfcA has nnpfc_formatting_and_purpose_flag equal to 1. Such an update to the NNPF is called a full update.

[0221] c. Repetitions of an NNPFC SEI message with a specific nnpfc_id value within the same CLVS are allowed to not be the first NNPFC SEI message with that specific value within the CLVS and are allowed to have nnpfc_formatting_and_purpose_flag equal to 1.

[0222] 5) To solve problem 5, the target neural network post-processing filter (NNPF) identified by nnpfa_target_id is the NNPF specified by the last NNPFC SEI message with nnpfc_id equal to nnpfa_target_id that precedes the NNPFA SEI message in decoding order.

[0223] 6) To address problem 6, specify the following: Let nnpfcTargetPictures be the set of pictures applied by the last NNPFC SEI message with nnpfc_id equal to nnpfa_target_id that precedes the NNPFA SEI message in decoding order. Let nnpfaTargetPictures be the set of pictures for which the target NNPF is activated by the current NNPFA SEI message. A bitstream conformance requirement is that any pictures included in nnpfaTargetPictures must also be included in nnpfcTargetPictures.

[0224] a. Alternatively, specify one or more of the following:

[0225] i. Specify: The NNPFC SEI message that specifies the base NNPF applies to the current picture of the current layer and all subsequent pictures in decoding order until the end of the current CLVS.

[0226] ii. Specify: An NNPFC SEI message specifying an update to the base NNPF applies to the current picture of the current layer and all subsequent pictures in decoding order until the end of the current CLVS, or until the next NNPFC SEI message in decoding order with that specific nnpfc_id value within the current CLVS.

[0227] 6. Examples

[0228] The following are some example embodiments of the aspects outlined in Section 5. Most relevant parts that have been added or modified are shown in bold font, and some of the deleted parts are shown in italic bold font. There may be some other changes that are of an editorial nature and are therefore not highlighted.

[0229] 6.1 First embodiment

[0230] This embodiment applies to items 1 through 6 and all sub-items thereof outlined in Section 5, excluding item 6.a.

[0231] 8.28.2 Neural Network Post-Processing Filter Characteristics SEI Message Semantics ...

[0233] nnpfc_id contains an identification number that can be used to identify the post-processing filter. The value of nnpfc_id must be between 0 and 2. 32 The value of nnpfc_id is from 256 to 511 (inclusive) and from 2 31 to 2 32-2 (inclusive) are reserved for future use by ITU-T|ISO / IEC. A decoder conforming to this version of this document shall encounter a nnpfc_id in the range 256 to 511 (inclusive) or in the range 256 to 511 (inclusive). 31 to 2 32 When an NNPFC SEI message is received in the range of -2 (inclusive), the SEI message shall be ignored.

[0234] When the NNPFC SEI message is the first NNPFC SEI message in decoding order for a specific nnpfc_id value within the current CLVS, the following applies:

[0235] – This SEI message specifies the base post-processing filters.

[0236] – This SEI message applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS.

[0237]

[0238] When an NNPFC SEI message is a repetition of a previous NNPFC SEI message in decoding order in the current CLVS, subsequent semantics apply as if the SEI message was the only NNPFC SEI message with the same content within the current CLVS.

[0239] When the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS, The following applies:

[0240] – This SEI message defines updates relative to the preceding base post-processing filter in decoding order with the same nnpfc_id value.

[0241] – This SEI message applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS or until the next decoded picture with this specific nnpfc_id value within the current CLVS. Next NNPFC SEI message ...

[0243] nnpfc_formatting_and_purpose_flag equal to 1 specifies that syntax elements related to filter purpose, input format, output format, and complexity are present. nnpfc_formatting_and_purpose_flag equal to 0 specifies that syntax elements related to filter purpose, input format, output format, and complexity are not present.

[0244] When this SEI message is the first NNPFC SEI message in decoding order with a particular nnpfc_id value within the current CLVS, nnpfc_formatting_and_purpose_flag shall be equal to 1. ...

[0246] 8.29.2 Neural Network Post-Processing Filter Activation SEI Message Semantics

[0247] The Neural Network Post-Processing Filter Activation (NNPFA) SEI message activates or deactivates the target neural network post-processing filter identified by nnpfa_target_id. Possible use of post-processing filtering on a set of images.

[0248] NOTE 1 – Multiple NNPFA SEI messages may exist for the same picture, for example when post-processing filters are used for different purposes or filter different color components. ...

[0250] nnpfa_persistence_flag specifies the persistence of the target neural network post-processing filters of the current layer.

[0251] nnpfa_persistence_flag equal to 0 specifies that the target neural network post-processing filter can only be used for post-processing filtering of the current image.

[0252] nnpfa_persistence_flag equal to 1 specifies that the target neural network post-processing filters can be used for post-processing filtering of the current picture and all subsequent pictures of the current layer in output order until one or more of the following conditions are true:

[0253] – A new CLVS starts for the current layer.

[0254] – End of bitstream.

[0255] – Output the pictures in the current layer that are associated with an NNPFA SEI message with the same nnpfa_target_id as the current SEI message and nnpfa_cancel_flag equal to 1, and that follow the current picture in output order.

[0256] NOTE 2 – The target neural network post-processing filter is not applied to this subsequent picture in the current layer that is associated with an NNPFA SEI message with the same nnpfa_target_id as the current SEI message and nnpfa_cancel_flag equal to 1.

[0257] ...

[0259] 7. References

[0260] [1]ITU-T and ISO / IEC, "High efficiency video coding", Rec.ITU-T H.265|ISO / IEC 23008-2 (in force edition).

[0261] [2] J.Chen, E.Alshina, GJSullivan, J.-R.Ohm, J.Boyce, "Algorithmdescription of Joint Exploration Test Model 7(JEM7)," JVET-G1001, Aug.2017.

[0262] [3]Rec.ITU-T H.266|ISO / IEC 23090-3, "Versatile Video Coding", 2022.

[0263] [4]Rec.ITU-T Rec.H.274|ISO / IEC 23002-7, "Versatile SupplementalEnhancement Information Messages for Coded Video Bitstreams", 2022.

[0264] [5]ISO / IEC JTC 1 / SC 29 / WG 05output document N0158, "Text of ISO / IEC23002-7:202x(2nd Ed.)DAM 1Information technology—MPEG video technologies—Part 7:Versatile supplemental enhancement information messages for codedvideo bitstreams,AMENDMENT 1:Additional SEI messages",Oct.2022.

[0265] [6]S.McCarthy,T.Chujoh,M.Hannuksela,G.Sullivan,and Y.-K.Wang(editors),"Additional SEI messages for VSEI(Draft 3),"JVET output documentJVET-AB2006,publicly available online herein:https: / / www.jvet-experts.org / doc_end_user / current_document.php? id=12215.

[0266] Figure 2 is a block diagram illustrating an example video processing system 4000 in which the 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.

[0267] System 4000 may include an encoding component 4004 that can implement the various codecs or encoding methods described in this document. Encoding component 4004 can reduce the average bit rate of the video from input 4002 to the output of encoding component 4004 to produce an encoded representation of the video. Coding technology is therefore sometimes referred to as video compression or video transcoding technology. The output of encoding component 4004 can be stored or transmitted via a communication connection such as represented by component 4006. The bitstream (or encoding) representation of the video stored or communicated received at input 4002 can be used by component 4008 to generate pixel values or displayable video that is transmitted to display interface 4010. The process of generating user-visible video from the bitstream representation is sometimes referred to as video decompression. In addition, although some video processing operations are referred to as "encoding" operations or tools, it should be understood that the encoding tools or operations are used at the encoder, and the corresponding decoding tools or operations that reverse the encoding results will be performed by the decoder.

[0268] 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, laptop computers, smartphones, or other devices capable of performing digital data processing and / or video display.

[0269] Figure 3 is a block diagram of an example video processing device 4100. Device 4100 can be used to implement one or more methods described herein. Device 4100 can be embodied in a smartphone, a tablet, a computer, an Internet of Things (IoT) receiver, etc. Device 4100 may include one or more processors 4102, one or more memories 4104, and video processing circuitry 4106. Processor(s) 4102 can be configured to implement one or more methods described in this document. Memory(s) 4104 can be used to store data and code for implementing the methods and techniques described herein. Video processing circuitry 4106 can be used to implement some of the techniques described in this document in hardware circuitry. In some embodiments, video processing circuitry 4106 can be at least partially included in processor 4102, for example, a graphics coprocessor.

[0270] Figure 44 is a flow chart of an example method 4200 for video processing. At step 4202, the method 4200 determines that when a second neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message (denoted as nnpfcB) has the same SEI payload content as a first NNPFC SEI message (denoted as nnpfcA), nnpfcB is a duplicate of nnpfcA. At step 4204, conversion is performed between visual media data and a bitstream based on nnpfcA and nnpfcB. The conversion can include encoding at an encoder, decoding at a decoder, or a combination thereof.

[0271] It should be noted that method 4200 can be implemented in an apparatus that processes video data, such as video encoder 4400, video decoder 4500, and / or encoder 4600, including a processor and non-transitory memory having instructions thereon. In this case, the instructions, when executed by the processor, cause the processor to perform method 4200. Furthermore, method 4200 can be performed by a non-transitory computer-readable medium that includes a computer program product for use with a video codec device. The computer program product includes computer-executable instructions stored on the non-transitory computer-readable medium that, when executed by the processor, cause the video codec device to perform method 4200.

[0272] Figure 5 4 is a block diagram illustrating an example video codec system 4300 that can utilize the techniques of this disclosure. Video codec system 4300 can include a source device 4310 and a destination device 4320. Source device 4310 generates encoded video data, where source device 4310 can be referred to as a video encoding device. Destination device 4320 can decode the encoded video data generated by source device 4310, where destination device 4320 can be referred to as a video decoding device.

[0273] Source device 4310 may include a video source 4312, a video encoder 4314, and an input / output (I / O) interface 4316. Video source 4312 may include a source such as a video capture device, an interface 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. The video data may include one or more pictures. Video encoder 4314 encodes the video data from video source 4312 to generate a bitstream. The bitstream may include a sequence of bits that form an encoded representation of the video data. The bitstream may include encoded pictures and associated data. An encoded picture is an encoded representation of a picture. The associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. I / O interface 4316 may include a modulator / demodulator (modem) and / or a transmitter. The encoded video data may be transmitted directly to target device 4320 via network 4330 via I / O interface 4316. The encoded video data may also be stored on storage medium / server 4340 for access by target device 4320.

[0274] 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 encoded video data from the source device 4310 or the storage medium / server 4340. The video decoder 4324 may decode the encoded video data. The display device 4322 may display the decoded video data to a user. The display device 4322 may be integrated with the target device 4320, or may be external to the target device 4320, wherein the target device 4320 may be configured to interface with an external display device.

[0275] 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 (VVM) standard, and other existing and / or future standards.

[0276] Figure 6 is a block diagram illustrating an example of a video encoder 4400, which may be Figure 5 Video encoder 4314 in system 4300 is shown. Video encoder 4400 can be configured to perform any or all of the techniques of this disclosure. Video encoder 4400 includes multiple functional components. The techniques described in this disclosure can be shared between the various components of video encoder 4400. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[0277] The functional components of the video encoder 4400 may include a segmentation unit 4401, a prediction unit 4402, 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 cache 4413 and an entropy coding unit 4414. The prediction unit 4402 may include a mode selection unit 4403, a motion estimation unit 4404, a motion compensation unit 4405 and an intra-frame prediction unit 4406.

[0278] In other examples, the video encoder 4400 may include more, fewer, or different functional components. In one example, the prediction unit 4402 may include an intra block copy (IBC) unit. The IBC unit may perform prediction in accordance with an IBC mode, where at least one reference picture is a picture in which the current video block is located.

[0279] Furthermore, some components, such as the motion estimation unit 4404 and the motion compensation unit 4405 , may be highly integrated, but for purposes of explanation, these components are represented separately in the example of the video encoder 4400 .

[0280] The segmentation unit 4401 may segment a picture into one or more video blocks. The video encoder 4400 and the video decoder 4500 may support various video block sizes.

[0281] The mode selection unit 4403 can, for example, select one of a plurality of codec modes (intra-frame codec or inter-frame codec) based on the error result, and provide the generated intra-frame codec block or inter-frame codec 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 can select a joint intra-frame and inter-frame prediction (CIIP) mode, in which prediction is based on an inter-frame prediction signal and an intra-frame prediction signal. In the case of inter-frame prediction, the mode selection unit 4403 can also select a resolution for the motion vector for the block (e.g., sub-pixel precision or integer pixel precision).

[0282] To perform inter-frame prediction on the current video block, the motion estimation unit 4404 may generate motion information for 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 for 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.

[0283] 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.

[0284] In some examples, motion estimation unit 4404 may perform unidirectional prediction on the current video block, and motion estimation unit 4404 may search the reference pictures in list 0 or list 1 to find a reference video block for the current video block. Motion estimation unit 4404 may then generate a reference index indicating the reference picture in list 0 or list 1 that contains the reference video block and a motion vector indicating the spatial displacement between the current video block and the reference video block. Motion estimation unit 4404 may output the reference index, prediction direction indicator, and motion vector as motion information for the current video block. Motion compensation unit 4405 may generate a predicted video block for the current block based on the reference video block indicated by the motion information of the current video block.

[0285] In other examples, motion estimation unit 4404 may perform bidirectional prediction on the current video block. Motion estimation unit 4404 may search the reference pictures in list 0 for a reference video block for the current video block, and may also search the reference pictures in list 1 for another reference video block for the current video block. Motion estimation unit 4404 may then generate reference indexes indicating the reference pictures in list 0 and list 1 that contain the reference video blocks, and a motion vector indicating the spatial displacement between the reference video blocks and the current video block. Motion estimation unit 4404 may output the reference index and motion vector for the current video block as motion information for the current video block. Motion compensation unit 4405 may generate a predicted video block for the current video block based on the reference video block indicated by the motion information of the current video block.

[0286] In some examples, motion estimation unit 4404 may output a complete set of motion information for use in the decoding process of 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 for 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 a neighboring video block.

[0287] In one example, the motion estimation unit 4404 may indicate to the video decoder 4500 a value in a syntax structure associated with the current video block that indicates that the current video block has the same motion information as another video block.

[0288] 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.

[0289] As discussed above, the video encoder 4400 can signal motion vectors in a predictive manner.Two examples of prediction signaling techniques that can be implemented by the video encoder 4400 include Advanced Motion Vector Prediction (AMVP) and Merge mode signaling.

[0290] Intra-frame prediction unit 4406 can perform intra-frame prediction on the current video block. When intra-frame prediction unit 4406 performs intra-frame prediction on the current video block, intra-frame prediction unit 4406 can 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 can include a predicted video block and various syntax elements.

[0291] The residual generation unit 4407 may generate residual data for the current video block by subtracting the predicted video blocks 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.

[0292] 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.

[0293] Transform processing unit 4408 may generate one or more transform coefficient video blocks for a current video block by applying one or more transforms to a residual video block associated with the current video block.

[0294] 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.

[0295] Inverse quantization unit 4410 and inverse transform unit 4411 may apply inverse quantization and inverse transform, respectively, to the transform coefficient video block to reconstruct a residual video block from the transform coefficient video block. Reconstruction unit 4412 may add the reconstructed residual video block to corresponding samples from one or more prediction video blocks generated by prediction unit 4402 to generate a reconstructed video block associated with the current block for storage in buffer 4413.

[0296] After the reconstruction unit 4412 reconstructs the video block, a loop filtering operation may be performed to reduce video blocking artifacts in the video block.

[0297] The entropy coding unit 4414 may receive data from other functional components of the video encoder 4400. When the entropy coding unit 4414 receives 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.

[0298] Figure 7 is a block diagram illustrating an example of a video decoder 4500, which may be Figure 5 Video decoder 4324 in system 4300 is shown. Video decoder 4500 can be configured to perform any or all of the techniques of this disclosure. In the example shown, video decoder 4500 includes multiple functional components. The techniques described in this disclosure can be shared between the various components of video decoder 4500. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[0299] In the example shown, video decoder 4500 includes an entropy decoding unit 4501, a motion compensation unit 4502, an intra-prediction unit 4503, an inverse quantization unit 4504, an inverse transform unit 4505, a reconstruction unit 4506, and a buffer 4507. In some examples, video decoder 4500 may perform a decoding process that is generally opposite to the encoding process described with respect to video encoder 4400.

[0300] The entropy decoding unit 4501 can retrieve the encoded bitstream. The encoded bitstream may include entropy-encoded video data (e.g., coded blocks of video data). The entropy decoding unit 4501 can decode the entropy-encoded video data, and based on the entropy-decoded video data, the motion compensation unit 4502 can determine motion information including motion vectors, motion vector precision, reference picture list index, and other motion information. The motion compensation unit 4502 can determine this information, for example, by performing AMVP and Merge modes.

[0301] The motion compensation unit 4502 may generate a motion compensated block and may perform interpolation 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.

[0302] The motion compensation unit 4502 may calculate interpolated values for sub-integer pixels of a reference block using interpolation filters as used by the video encoder 4400 during encoding of the video block. The motion compensation unit 4502 may determine the interpolation filters used by the video encoder 4400 based on received syntax information, and the motion compensation unit 4502 may use the interpolation filters to generate a prediction block.

[0303] 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.

[0304] The intra prediction unit 4503 can 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.

[0305] The reconstruction unit 4506 can add the residual block to the corresponding prediction block generated by the motion compensation unit 4502 or the intra-frame prediction unit 4503 to form a decoded block. If necessary, a deblocking filter can also be used to filter the decoded block to remove blocking artifacts. The decoded video block is then stored in the buffer 4507, which provides reference blocks for subsequent motion compensation / intra-frame prediction and also produces the decoded video for presentation on a display device.

[0306] Figure 8 is a schematic diagram of an example encoder 4600. The encoder 4600 is suitable for implementing techniques for VVC. 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, which 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, and using the encoded side information to signal the offset and filter coefficients. The ALF 4606 is located at the last processing stage for each picture and can be seen as a tool that attempts to capture and repair artifacts caused by previous stages.

[0307] The encoder 4600 also includes an intra-frame prediction component 4608 and a motion estimation / compensation (ME / MC) component 4610 configured to receive input video. The intra-frame prediction component 4608 is configured to perform intra-frame prediction, and the ME / MC component 4610 is configured to perform inter-frame prediction using reference pictures obtained from a reference picture cache 4612. The residual block from the inter-frame prediction or intra-frame prediction is fed into a transform (T) component 4614 and a quantization (Q) component 4616 to generate quantized residual transform coefficients, which are fed into an entropy coding component 4618. The entropy coding component 4618 entropy encodes the prediction results and quantized transform coefficients and transmits them to a video decoder (not shown). The quantized components output from the quantization component 4616 can be fed into an inverse quantization (IQ) component 4620, an inverse transform component 4622, and a reconstruction (REC) component 4624. The REC component 4624 can output images to the DF 4602 , SAO 4604 , and ALF 4606 for filtering before these images are stored in the reference picture cache 4612 .

[0308] Figure 9 47 is a flow chart of an example method 4700 for video processing. Method 4700 determines an NNPFC SEI message at step 4702. The NNPFC SEI message applies to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of the current CLVS, or up to but not including a decoded picture within the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having nnpfc_base_flag equal to 0 and a particular nnpfc_id value within the current CLVS, whichever is earlier. At step 4704, conversion is performed between visual media data and a bitstream based on the NNPFC SEI message. The conversion may include encoding at an encoder, decoding at a decoder, or a combination thereof.

[0309] It should be noted that method 4700 can be implemented in a device that processes video data, such as video encoder 4400, video decoder 4500, and / or encoder 4600, including a processor and non-transitory memory having instructions thereon. In this case, the instructions, when executed by the processor, cause the processor to perform method 4700. Furthermore, method 4700 can be performed by a non-transitory computer-readable medium that includes a computer program product for use with a video codec device. The computer program product includes computer-executable instructions stored on the non-transitory computer-readable medium that, when executed by the processor, cause the video codec device to perform method 4700.

[0310] A list of some example preferred solutions is provided below.

[0311] The following solutions illustrate examples of the techniques discussed herein.

[0312] 1. A method for processing media data, comprising: determining that when a second neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message (denoted as nnpfcB) has the same SEI payload content as a first NNPFC SEI message (denoted as nnpfcA), nnpfcB is a repetition of nnpfcA; and performing conversion between visual media data and a bitstream based on the nnpfcA and the nnpfcB.

[0313] 2. The method according to solution 1, wherein, when the fifth NNPFC SEI message (denoted as nnpfcE) is a repetition of the fourth NNPFC SEI message (denoted as nnpfcD), and nnpfcD is a repetition of the third NNPFC SEI message (denoted as nnpfcC), nnpfcE is a repetition of nnpfcC.

[0314] 3. A method according to any one of solutions 1-2, wherein the updating of the basic neural network post-processing filter (NNPF) is based on the following condition: when the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a specific NNPFC identifier (nnpfc_id) value in the current codec layer video sequence (CLVS), and is not a repetition of another NNPFC SEI message with the same nnpfc_id value in the current CLVS.

[0315] 4. A method according to any of solutions 1-3, wherein the NNPFC SEI message specifying an update to the base NNPF applies to the current decoded picture of the current layer and all subsequent decoded pictures in output order until the end of the current CLVS, or until the next NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS.

[0316] 5. The method according to any of solutions 1-4, wherein when the NNPFC SEI message is not the first NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS, the NNPFC format and purpose flag (nnpfc_formatting_and_purpose_flag) is allowed to be equal to 0 or 1.

[0317] 6. The method of any of solutions 1-5, wherein when a nnpfcA with a particular nnpfc_id value within a CLVS provides an update to an NNPF specified by a previous NNPFC SEI message with the same nnpfc_id value within the CLVS, the update to the NNPF is a full update and the nnpfcA has a nnpfc_formatting_and_purpose_flag equal to 1.

[0318] 7. The method according to any of solutions 1-6, wherein repetitions of NNPFC SEI messages with a specific nnpfc_id value within the same CLVS are allowed to not be the first NNPFC SEI message with the specific value within the CLVS and are allowed to have nnpfc_formatting_and_purpose_flag equal to 1.

[0319] 8. The method according to any one of solutions 1-7, wherein the target NNPF identified by the NNPFC target identifier (nnpfa_target_id) is the NNPF specified by the last NNPFC SEI message with nnpfc_id equal to nnpfa_target_id that precedes the current NNPFA SEI message in decoding order.

[0320] 9. A method according to any of solutions 1-8, wherein NNPFC target pictures (nnpfcTargetPictures) is the set of pictures applicable by the last NNPFC SEI message with nnpfc_id equal to nnpfa_target_id that precedes the current NNPFA SEI message in decoding order; NNPFA target pictures (nnpfaTargetPictures) is the set of pictures for which the target NNPF is activated by the current NNPFA SEI message, and any pictures included in nnpfaTargetPictures must also be included in nnpfcTargetPictures.

[0321] 10. The method according to any of solutions 1-9, wherein the NNPFC SEI message specifying the base NNPF is applicable to the current picture and all subsequent pictures of the current layer in decoding order until the end of the current CLVS.

[0322] 11. A method according to any of solutions 1-10, wherein the NNPFC SEI message specifying an update to the base NNPF applies to the current picture and all subsequent pictures of the current layer in decoding order until the end of the current CLVS, or until the next NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS.

[0323] 12. An apparatus 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 the method according to any one of solutions 1-11.

[0324] 13. 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 a method according to any one of solutions 1-11.

[0325] 14. A non-transitory computer-readable recording medium storing a bitstream of a video generated by a method performed by a video processing device, wherein the method includes: determining that when a second neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message (denoted as nnpfcB) has the same SEI payload content as a first NNPFC SEI message (denoted as nnpfcA), nnpfcB is a repetition of nnpfcA; and generating a bitstream based on the determination.

[0326] 15. A method for storing a bitstream of a video, comprising: determining that when a second neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message (denoted as nnpfcB) has the same SEI payload content as a first NNPFC SEI message (denoted as nnpfcA), nnpfcB is a repetition of nnpfcA; generating a bitstream based on the determination; and storing the bitstream in a non-transitory computer-readable recording medium.

[0327] 16. A method, apparatus or system as described in this document.

[0328] The following solutions illustrate further examples of the techniques discussed herein.

[0329] 1. A method of processing media data, comprising: determining a neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message is applicable to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of a current codec layer video sequence (CLVS), or until but not including a decoded picture within the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a specific NNPFC identifier (nnpfc_id) value within the current CLVS, whichever is earlier; and performing conversion between visual media data and a bitstream based on the NNPFC SEI message.

[0330] 2. The method of solution 1, wherein the NNPFC SEI message specifies updates to an underlying neural network post-processing filter (NNPF).

[0331] 3. The method according to any one of solutions 1-2, wherein when the NNPFC base flag (nnpfc_base_flag) is equal to 1, the flag indicating the presence of the NNPFC attribute parameter must be equal to 1.

[0332] 4. A method according to any one of solutions 1-3, wherein, when the NNPFC SEI message is not the first NNPFC SEI message in the current CLVS with the specific nnpfc_id value in decoding order, the flag indicating the presence of the NNPFC attribute parameter is allowed to be equal to 0 or 1.

[0333] 5. A method according to any one of solutions 1-4, wherein nnpfcTargetPictures is the set of pictures to which the NNPFC SEI message corresponding to the target NNPF applies, nnpfaTargetPictures is the set of pictures for which the target NNPF is activated by the current neural network post-processing filter activation (NNPFA) SEI message, and bitstream consistency requires that any pictures included in nnpfaTargetPictures must also be included in nnpfcTargetPictures.

[0334] 6. The method according to any of solutions 1-5, wherein nnpfcTargetPictures is the set of pictures applicable by the last NNPFC SEI message preceding the NNPFA SEI message in decoding order and with nnpfc_id equal to the NNPFA target identifier (nnpfa_target_id).

[0335] 7. The method of any one of solutions 1-6, wherein when a second neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message (denoted as nnpfcB) has the same SEI payload content as a first NNPFC SEI message (denoted as nnpfcA), nnpfcB is a repetition of nnpfcA.

[0336] 8. A method according to any one of solutions 1-7, wherein, when the fifth NNPFC SEI message (denoted as nnpfcE) is a repetition of the fourth NNPFC SEI message (denoted as nnpfcD), and nnpfcD is a repetition of the third NNPFC SEI message (denoted as nnpfcC), nnpfcE is a repetition of nnpfcC.

[0337] 9. A method according to any one of solutions 1-8, wherein the update of the basic NNPF is based on the following conditions: when the NNPFC SEI message is not the first NNPFC SEI message in the decoding order with the specific nnpfc_id value in the current CLVS, and the NNPFC SEI message is not a repetition of another NNPFC SEI message with the same nnpfc_id value in the current CLVS.

[0338] 10. A method according to any of solutions 1-9, wherein when a nnpfcA with a specific nnpfc_id value within the CLVS provides an update to the NNPF specified by a previous NNPFC SEI message with the same nnpfc_id value within the CLVS, and when nnpfcA has a flag equal to 1 indicating the presence of NNPFC attribute parameters, the update to the NNPF is a full update.

[0339] 11. A method according to any of solutions 1-10, wherein repetition of an NNPFC SEI message with a specific nnpfc_id value within the same CLVS is allowed to not be the first NNPFC SEI message with the specific value within the CLVS, and is allowed to have a flag indicating the presence of an NNPFC attribute parameter equal to 1.

[0340] 12. The method according to any one of solutions 1-11, wherein the target NNPF identified by nnpfa_target_id is the NNPF specified by the last NNPFC SEI message preceding the current NNPFA SEI message in decoding order and having nnpfc_id equal to nnpfa_target_id.

[0341] 13. A method according to any one of solutions 1-12, wherein the NNPFC SEI message specifies a base NNPF, which is applicable to the current picture and all subsequent pictures of the current layer in decoding order until the end of the current CLVS.

[0342] 14. A method according to any one of solutions 1-13, wherein the NNPFC SEI message specifying an update to the base NNPF applies to the current picture and all subsequent pictures of the current layer in decoding order until the end of the current CLVS, or until the next NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS.

[0343] 15. The method of any of solutions 1-14, wherein the converting comprises encoding the visual media data into the bitstream.

[0344] 16. The method of any of solutions 1-14, wherein the converting comprises decoding the visual media data from the bitstream.

[0345] 17. A device for processing video data, comprising: a processor; and a non-volatile memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform the method according to any one of solutions 1-16.

[0346] 18. 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, which, when executed by a processor, cause the video codec device to perform a method according to any one of Solutions 1-16.

[0347] 19. A non-transitory computer-readable recording medium storing a bitstream of a video generated by a method performed by a video processing device, wherein the method comprises: determining a neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message is applicable to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of a current codec layer video sequence (CLVS), or until but not including a decoded picture in the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a specific NNPFC identifier (nnpfc_id) value in the current CLVS, whichever is earlier; and generating a bitstream based on the determination.

[0348] 20. A method for storing a bitstream of a video, comprising: determining a neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message is applicable to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of a current codec layer video sequence (CLVS), or until but not including a decoded picture in the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a specific NNPFC identifier (nnpfc_id) value in the current CLVS, whichever is earlier; generating a bitstream based on the determination; and storing the bitstream in a non-transitory computer-readable recording medium.

[0349] In the described solution, an encoder can conform to the format rules by generating an encoded representation according to the format rules. In the described solution, a decoder can parse syntax elements in the encoded representation according to the format rules using known information about the presence and absence of syntax elements to generate decoded video.

[0350] In this document, the term "video processing" may refer to video encoding, video decoding, video compression, or video decompression. For example, a video compression algorithm may be applied during the conversion from a pixel representation of a video to a corresponding bitstream representation, or vice versa. For example, the bitstream representation of a current video block may correspond to bits spread across the same position in the bitstream or at different positions as defined by the syntax. For example, a macroblock may be encoded based on error residual values after transformation and encoding, and bits in headers and other fields in the bitstream may also be used. Furthermore, during conversion, the decoder may parse the bitstream based on this determination, using known information that some fields may or may not be present, as described in the above solution. Similarly, an encoder may determine whether to include or not include particular syntax fields, and the encoder may generate the encoded and decoded representation accordingly by including or excluding the syntax fields from the encoded and decoded representation.

[0351] The disclosed and other solutions, examples, embodiments, modules, and functional operations described in this document may be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in a combination of one or more thereof. The disclosed and other embodiments may be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by a data processing apparatus or to control the operation of the data processing apparatus. The computer-readable medium may be a machine-readable storage device, a machine-readable storage substrate, a storage device, a composition of matter that effects a machine-readable propagated signal, or a combination of one or more thereof. The term "data processing apparatus" includes all apparatus, devices, and machines for processing data, including, for example, a programmable processor, a computer, or multiple processors or computers. In addition to hardware, an apparatus may also include code that creates an execution environment for an associated computer program, such as code constituting processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more thereof. A propagated signal is an artificially generated signal, such as a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to a suitable receiver device.

[0352] A computer program (also referred to as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including stand-alone programs or modules, components, subroutines, or other units suitable for use in a computing environment. A computer program need not necessarily correspond to a file in a file system. A program can be stored in a portion of a file preserving 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 collaborative files (e.g., files storing one or more modules, subroutines, or code portions). A computer program can be deployed to execute on one computer or on multiple computers, which are located at a site or distributed across multiple sites and interconnected by a communication network.

[0353] The processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special-purpose logic circuitry, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

[0354] Processors suitable for executing computer programs include, for example, general-purpose and special-purpose microprocessors, as well as any one or more processors of any type of digital computer. Typically, a processor will receive instructions and data from read-only memory or random access memory, or both. The essential elements of a computer are a processor that executes instructions and one or more memory devices that store instructions and data. Typically, a computer will also include one or more mass storage devices for storing data, such as magnetic disks, magneto-optical disks, or optical disks. However, a computer need not necessarily have such devices. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and storage 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 or removable hard 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 memory may be supplemented by, or incorporated into, dedicated logic circuitry.

[0355] Although this patent document contains many details, these details should not be construed as limitations on any subject matter or the scope of what may be claimed, but rather as descriptions of features unique to particular embodiments of particular technologies. In this patent document, certain features described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable subcombination. In addition, although features may function in certain combinations as described above and may even be initially claimed in this manner, in some cases, one or more features in a claimed combination may be omitted from the combination, and the claimed combination may be directed to a subcombination or a variation of a subcombination.

[0356] Similarly, while operations may be depicted in a particular order in the drawings, this should not be understood as requiring that such operations be performed sequentially in the particular order or sequence shown, or that all illustrated operations be performed to achieve desired results. Furthermore, the partitioning of various system components in the embodiments described in this patent document should not be understood as requiring such partitioning in all embodiments.

[0357] Only a few implementations and examples are described, and other implementations, improvements, and variations can be made based on what is described and illustrated in this patent document.

[0358] A first component is directly coupled to a second component when there are no intervening components other than a wire, trace, or other medium between the first and second components. A first component is indirectly coupled to a second component when there are intervening components other than a wire, trace, or other medium between the first and second components. The term "coupled" and its variations encompass both direct and indirect couplings. The use of the term "about" is intended to encompass a range of ±10% of the subsequent figure unless otherwise indicated.

[0359] Although a number of embodiments are provided in this 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 should be considered 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.

[0360] In addition, 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 without departing from the scope of this disclosure. Other items illustrated 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 this disclosure.

Claims

1. A method for processing media data, comprising: determining a neural network post-processing filter characteristics (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message applies to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of a current codec layer video sequence (CLVS), or up to but not including a decoded picture within the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a particular NNPFC identifier (nnpfc_id) value within the current CLVS, whichever is earlier; and Conversion between visual media data and a bitstream is performed based on the NNPFC SEI message.

2. The method according to claim 1, wherein The NNPFC SEI message specifies updates to the underlying neural network post-processing filter (NNPF).

3. The method according to claim 1 or 2, wherein When the NNPFC base flag (nnpfc_base_flag) is equal to 1, the flag indicating the presence of the NNPFC attribute parameter shall be equal to 1.

4. The method according to any one of claims 1 to 3, wherein When the NNPFC SEI message is not the first NNPFC SEI message in decoding order with the specific nnpfc_id value within the current CLVS, the flag indicating the presence of NNPFC attribute parameters is allowed to be equal to 0 or 1.

5. The method according to any one of claims 1 to 4, wherein nnpfcTargetPictures is the set of pictures to which the NNPFC SEI message corresponding to the target NNPF applies, nnpfaTargetPictures is the set of pictures for which the target NNPF is activated by the current neural network post-processing filter activation (NNPFA) SEI message, and bitstream consistency requires that any pictures included in nnpfaTargetPictures must also be included in nnpfcTargetPictures.

6. The method according to any one of claims 1 to 5, wherein nnpfcTargetPictures is the set of pictures to which the last NNPFC SEI message preceding the NNPFA SEI message in decoding order and with nnpfc_id equal to the NNPFA target identifier (nnpfa_target_id) applies.

7. The method according to any one of claims 1 to 6, wherein When the second neural network post-processing filter characteristic (NNPFC) supplemental enhancement information (SEI) message (denoted as nnpfcB) has the same SEI payload content as the first NNPFC SEI message (denoted as nnpfcA), nnpfcB is a repetition of nnpfcA.

8. The method according to any one of claims 1 to 7, wherein When the fifth NNPFC SEI message (denoted as nnpfcE) is a repetition of the fourth NNPFC SEI message (denoted as nnpfcD), and nnpfcD is a repetition of the third NNPFC SEI message (denoted as nnpfcC), nnpfcE is a repetition of nnpfcC.

9. The method according to any one of claims 1 to 8, wherein The update of the base NNPF is based on the following conditions: when the NNPFC SEI message is not the first NNPFC SEI message in the decoding order with the specific nnpfc_id value in the current CLVS, and the NNPFC SEI message is not a repetition of another NNPFC SEI message with the same nnpfc_id value in the current CLVS.

10. The method according to any one of claims 1 to 9, wherein When a nnpfcA with a particular nnpfc_id value within a CLVS provides an update to the NNPF specified by a previous NNPFC SEI message with the same nnpfc_id value within the CLVS, and when nnpfcA has a flag equal to 1 indicating the presence of NNPFC attribute parameters, the update to the NNPF is a full update.

11. The method according to any one of claims 1 to 10, wherein Repetitions of NNPFC SEI messages with a specific nnpfc_id value within the same CLVS are allowed to not be the first NNPFC SEI message with the specific value within the CLVS and are allowed to have a flag equal to 1 indicating the presence of NNPFC attribute parameters.

12. The method according to any one of claims 1 to 11, wherein The target NNPF identified by nnpfa_target_id is the NNPF specified by the last NNPFC SEI message preceding the current NNPFA SEI message in decoding order and having nnpfc_id equal to nnpfa_target_id.

13. The method according to any one of claims 1 to 12, wherein The NNPFC SEI message specifies a base NNPF that applies to the current picture of the current layer and all subsequent pictures in decoding order until the end of the current CLVS.

14. The method according to any one of claims 1 to 13, wherein: An NNPFC SEI message specifying an update to the base NNPF applies to the current picture of the current layer and all subsequent pictures in decoding order until the end of the current CLVS, or until the next NNPFC SEI message in decoding order with a specific nnpfc_id value within the current CLVS.

15. The method according to any one of claims 1 to 14, wherein The converting includes encoding the visual media data into the bitstream.

16. The method according to any one of claims 1 to 14, wherein The converting includes decoding the visual media data from the bitstream.

17. 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 1-16.

18. A non-transitory computer-readable medium comprising a computer program product for use with a video encoding and decoding device, wherein: The computer program product includes computer-executable instructions stored on the non-transitory computer-readable medium, which, when executed by a processor, cause the video coding device to perform the method according to any one of claims 1 to 16.

19. A non-transitory computer-readable recording medium storing a bit stream of a video generated by a method performed by a video processing apparatus, wherein The method comprises: determining a neural network post-processing filter characteristics (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message applies to a current decoded picture of a current layer and all subsequent decoded pictures in output order until the end of a current codec layer video sequence (CLVS), or up to but not including a decoded picture within the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a particular NNPFC identifier (nnpfc_id) value within the current CLVS, whichever is earlier; and A bitstream is generated based on the determination.

20. A method for storing a bitstream of a video, comprising: determining a neural network post-processing filter characteristics (NNPFC) supplemental enhancement information (SEI) message, wherein the NNPFC SEI message applies to a current decoded picture of a current layer and all subsequent decoded pictures in the decoding order, up to the end of a current codec layer video sequence (CLVS), or up to but not including a decoded picture within the current CLVS that follows the current decoded picture in output order and is associated with a subsequent NNPFC SEI message in decoding order having an NNPFC base flag (nnpfc_base_flag) equal to 0 and a particular NNPFC identifier (nnpfc_id) value within the current CLVS, whichever is earlier; generating a bitstream based on the determination; and The bitstream is stored in a non-transitory computer-readable recording medium.

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