Handling of a processing chain indicated by an SEI processing order SEI message

Abstract

A mechanism for processing video data is disclosed. The mechanism includes determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list. A conversion is performed between a visual media data and a bitstream based on the processing chain.

Description

Handling Of A Processing Chain Indicated By An SEI Processing Order SEI Message CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority to and benefits of U.S. Provisional Patent Application No. 63 / 636,842, filed on April 21, 2024 and U.S. Provisional Patent Application No.63 / 671,566, filed on July 15, 2024. All the aforementioned patent applications are hereby incorporated by reference in their entireties. TECHNICAL FIELD

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

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

[0004] A first aspect relates to a method for processing video data comprising: processing chains; determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; and performing a conversion between a visual media data and a bitstream based on the processing chain.

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

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

[0007] A fourth aspect relates to a non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; and generating a bitstream based on the determining.

[0008] A fifth aspect relates to a method for storing bitstream of a video comprising: determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

[0009] For the purpose of clarity, any one of the foregoing embodiments may be combined with any one or more of the other foregoing embodiments to create a new embodiment within the scope of the present disclosure.

[0010] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0012] FIG.1 is a block diagram showing an example video processing system.

[0013] FIG.2 is a block diagram of an example video processing apparatus.

[0014] FIG.3 is a flowchart for an example method of video processing.

[0015] FIG.4 is a block diagram that illustrates an example video coding system.

[0016] FIG.5 is a block diagram that illustrates an example encoder.

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

[0018] FIG.7 is a schematic diagram of an example encoder.

[0019] FIG.8 is a flowchart for an example method of video processing. DETAILED DESCRIPTION

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

[0021] Section headings are used in the present document for ease of understanding and do not limit the applicability of techniques and embodiments disclosed in each section only to that section. Furthermore, H.266 terminology is used in some description only for ease of understanding and not for limiting scope of the disclosed techniques. As such, the techniques described herein are applicable to other video codec protocols and designs also. In the present document, editing changes are shown to text by bold italics indicating cancelled text and bold indicating added text, with respect to the Versatile Video Coding (VVC) specification and / or the SEI messages for coded video bitstreams (VSEI) standard. 1. Initial discussion

[0022] This document is related to image / video coding technologies. Specifically, this disclosure is related to the filtering process for handling of a post-processing filter group, including supplemental enhancement information (SEI) message types, each implying a post-filtering process, indicated in an SEI processing order (SPO)SEI message. The ideas may be applied individually or in various combinations, for video bitstreams coded by any codec, e.g., the VVC standard and / or the versatile SEI messages for coded video bitstreams (VSEI) standard. 2. Further discussion 2.1 Video coding standards

[0023] Video coding standards have evolved primarily through the development of International Telecommunication Union (ITU) telecommunication standardization sector (ITU-T) and International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC) standards. The ITU-T produced H.261 and H.263, ISO / IEC produced motion picture experts group (MPEG)-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262 / MPEG-2 Video and H.264 / MPEG-4 Advanced Video Coding (AVC) and H.265 / high efficiency video coding (HEVC) [1] standards. Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized. The Versatile Video Coding (VVC) standard (ITU-T H.266 | ISO / IEC 23090-3) [2] and the associated Versatile Supplemental Enhancement Information for coded video bitstreams (VSEI) standard (ITU-T H.274 | ISO / IEC 23002-7) [3] are designed for use in a maximally broad range of applications, including both the simple uses such as television broadcast, video conferencing, or playback from storage media, and also more advanced use cases such as adaptive bit rate streaming, video region extraction, composition and merging of content from multiple coded video bitstreams, multiview video, scalable layered coding, and viewport-adaptive 360° immersive media. 2.2 SEI messages in general and in VVC

[0024] SEI messages assist in processes related to decoding, display or other purposes. However, SEI messages are not required for constructing the luma or chroma samples by the decoding process. Conforming decoders are not required to process this information for output order conformance. Some SEI messages are required for checking bitstream conformance and for output timing decoder conformance. Other SEI messages are not required for check bitstream conformance.

[0025] Annex D of VVC specifies syntax and semantics for SEI message payloads for some SEI messages, and specifies the use of the SEI messages and video usability information (VUI) parameters for which the syntax and semantics are specified in ITU-T H.SEI | ISO / IEC 23002-7. 2.3 The SEI processing order (SPO) SEI message

[0026] JVET-AG2027 [4] includes the specification of an SEI message named the SEI processing order (SPO) SEI message, for carrying information indicating the preferred processing order, as determined by the encoder (i.e., the content producer), for different types of SEI messages that may be present in a coded video stream (CVS) of the bitstream.

[0027] The specification of the SPO SEI message in JVET-AG2027 is as follows. 2.3.1 General SEI payload syntaxsei_payload( payloadType, payloadSize ) { Descriptor SeiExtensionBitsPresentFlag = 0. S processng or er S message synax sei_processing_order( payloadSize ) { Descriptorpo_num_bits_in_prefix_indication_minus1[ i ] u(8) for( j = 0; j <= po_num_bits_in_prefix_indication_minus1[ i ]; j++ ) 2

[0028] The SEI processing order (SPO) SEI message carries information indicating the preferred processing order, as determined by the encoder (i.e., the content producer), for a group of types of SEI messages that may be present in a CVS.

[0029] The semantics of the SPO SEI message uses the concept of types of SEI messages. SEI messages that have different payloadType values are considered different types of SEI messages. Additionally, different SEI messages that have the same payloadType value but are differentiated by values of syntax elements in the SEI payload are considered different types of SEI messages. Such differentiation by values of syntax elements in the SEI payload is to be performed by comparing values sent using po_sei_prefix_data_bit[ i ][ j ] syntax elements (when present) or values sent as SEI messages within a processing order nesting SEI message (when present). For example, neural-network post-filter (NNPF) characteristics (NNPFC) SEI messages can be differentiated by having different nnpfc_id values.

[0030] When the i-th SEI message seiA in any SPO SEI message has po_sei_wrapping_flag[ i ] and po_sei_prefix_flag[ i ] both equal to 0, there shall be no other SEI message seiB included in the same SPO SEI message or in a different SPO SEI message in the current CVS for which all of the following are true: – The value of po_sei_payload_type[ i ] of seiB is the same as that for seiA. – The value of po_sei_wrapping_flag[ i ] of seiB is equal to 0. – The value of po_sei_prefix_flag[ i ] of seiB is equal to 1.

[0031] When an SPO SEI message with a particular value of po_id is present in any access unit of a CVS, an SPO SEI message with that particular value of po_id shall be present in the first access unit of the CVS in decoding order. The number of SEI messages and the payloadType codes of the SEI messages indicated within each SPO SEI message with the same value of po_id persist in decoding order from the current access unit until the end of the CVS in output order.

[0032] The SPO SEI message can carry one or more SEI prefix indications of a particular payloadType. When present, each SEI prefix indication is a bit string that follows the SEI payload syntax of that value of payloadType and contains a number of complete syntax elements starting from the first syntax element in the SEIpayload. These SEI prefix indications should provide sufficient information to determine the specific processing order for types of SEI messages having the same value of payloadType but a different preferred processing order.

[0033] po_id contains an identifying number to identify the SPO SEI message.

[0034] A processing chain consists of a list of types of SEI messages identified by an SPO SEI message in the preferred processing order indicated in the SPO SEI message.

[0035] Each type of SEI message in the processing chain indicated by an SPO SEI message is identified by the syntax elements po_sei_payload_type[ i ], po_sei_wrapping_flag[ i ], po_sei_processing_order[ i ] and, when present, po_num_bits_in_prefix_indication_minus1[ i ] and po_prefix_data_bit[ i ][ j ].

[0036] An SEI message type is not required to belong to any processing chain and may belong to any number of processing chains identified by SPO SEI messages with different po_id values.

[0037] Each SEI message of an SEI message type identified within the SPO SEI message has the same persistence scope as if the SEI message was carried outside of the SPO SEI message and not identified within an SPO SEI message.

[0038] NOTE 1 – Processing chains can be alternatives to each other, i.e., such that at most processing chain is chosen to be applied, or they can be complementary, i.e., such that more than one processing chain is chosen and applied separately, with each processing chain generating one output.

[0039] po_num_sei_messages_minus2 plus 2 indicates the number of types of SEI messages for which the preferred order of processing is indicated in the SPO SEI message.

[0040] po_sei_wrapping_flag[ i ] equal to 1 specifies that one or more processing order nesting SEI messages with both of the following constraints should be present: – pon_target_po_id[ j ] with any value of j is equal to po_id. – There is a k-th loop entry in the processing order nesting SEI message such that the payloadType of the k-th nested SEI message is equal to po_sei_payload_type[ i ] and pon_processing_order[ k ] is equal to po_sei_processing_order[ i ].

[0041] When po_sei_wrapping_flag[ i ] is equal to 0, an SEI message with payloadType equal to po_sei_payload_type[ i ] (and, when po_sei_prefix_flag[ i ] equal to 1, prefix data that matches the values of po_sei_prefix_data_bit[ i ][ j ]) should be present outside of the processing order nesting SEI message.

[0042] NOTE 2 – po_sei_wrapping_flag[ i ] equal to 1 enables SEI messages to be carried within the processing order nesting SEI message to prevent such SEI messages from being incorrectly interpreted by decoders that do not process the SPO SEI message. Thus, po_sei_wrapping_flag[ i ] equal to 1 is intended to be used when po_sei_wrapping_flag[ i ] equal to 0 can lead to unintended results being produced by such decoders.

[0043] po_sei_importance_flag[ i ] indicates the degree of importance determined by the encoder for the type of SEI message with index i.

[0044] If the decoding system cannot interpret or does not support the functionality indicated by any indicated SEI message that has po_sei_importance_flag[ i ] equal to 1, it should ignore the entire SPO SEI message.

[0045] po_sei_payload_type[ i ] specifies the payloadType value of the i-th type of SEI message.

[0046] po_sei_prefix_flag[ i ] equal to 1 specifies that po_num_bits_in_prefix_indication_minus1[ i ] and some po_sei_prefix_data_bit[ i ][ j ] syntax elements are present. po_sei_prefix_flag[ i ] equal to 0 specifies that these syntax elements are not present.

[0047] SeiProcessingOrderSeiList is set to consist of the payloadType values 3, 4, 5, 19, 137, 142, 144, 147, 148, 149, 165, 177, 210, and 211. The value of po_sei_payload_type[ i ] for each i in the range of 0 to po_num_sei_messages_minus2 + 1, inclusive, shall be equal to a value in SeiProcessingOrderSeiList.

[0048] po_sei_processing_order[ i ] indicates the preferred order of processing of the i-th type of SEI message for which preferred processing order information is provided in the SPO SEI message. For any two different integer values of m and n, po_sei_processing_order[ m ] less than po_sei_processing_order[ n ] indicates that the type of SEI message associated with index m should be processed before the type of SEI message associated with index n, and po_sei_processing_order[ m ] equal to po_sei_processing_order[ n ] indicates that there is no preferred order of processing between the types of SEI messages associated with indexes m and n (e.g., they can indicate different properties that are both applicable at that stage, or alternative processes that can be applied, or one can indicate a property and the other can indicate a process).

[0049] For i greater than 0, po_sei_processing_order[ i ] shall be greater than or equal to po_sei_processing_order[ i − 1 ].

[0050] po_num_bits_in_prefix_indication_minus1[ i ] and po_sei_prefix_data_bit[ i ][ j ], when present, have the same semantics as the num_bits_in_prefix_indication_minus1[ i ] and sei_prefix_data_bit[ i ][ j ] syntax elements of the SEI prefix indication SEI message, with prefix_sei_payload_type replaced by po_sei_payload_type[ i ].

[0051] When more than one SPO SEI message with a particular value of po_id is present in a CVS, the values of po_num_sei_messages_minus2 and, for each value of i, the values of po_sei_wrapping_flag[ i ], po_sei_prefix_flag[ i ], po_sei_importance_flag[ i ], po_sei_payload_type[ i ], po_sei_processing_order[ i ] shall be the same as in the other SPO SEI messages in the CVS with the same value of po_id.

[0052] po_byte_alignment_bit_equal_to_one shall be equal to 1. 2.4. Handling of a processing chain

[0053] One way specifying the hanlding of a processing chain is as follows: Handling of a processing chain

[0054] A decoding system should apply at most one processing chain at one time.

[0055] A decoding system may apply a processing chain as follows: – First, the bitstream is decoded, and the list PoPicList is set to be the list of the cropped decoded pictures in output order that resulted from decoding the bitstream. – For each type of an SEI message, the following applies in a non-decreasing order of po_sei_processing_order[ i ] values:– The following applies for each picture picA in PoPicList in output order, when an SEI message that is associated with the i-th type of an SEI message persists for picA: – When picA is not a cropped decoded picture, the following exceptions apply for the interpretation of the SEI message: – The interface variables for purposes of interpretation of the SEI message are derived from picA instead of the syntax elements indicating properties for the respective cropped decoded picture. – The semantics of the SEI message apply to pictures in PoPicList instead of cropped decoded pictures. – When the i-th type of an SEI message implies a process, the process is performed and PoPicList is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process in PoPicList so that the output order is obeyed. 3. Technical problems solved by disclosed technical solutions

[0056] An example design for handling of a process chain has the following problems:

[0057] First, it is specified that a decoding system should apply at most one processing chain at one time. That means a decoding system may apply more than one processing chain at one time.

[0058] Second, the choosing of a processing chain is not included in the specification of the handling of a processing chain.

[0059] Third, it is not clearly specified that the SEI message types involved shall belong to the chosen processing chain.

[0060] Fourth, when the SEI message that persists for the current picture is an neural-network post-filter activation (NNPFA) SEI message, the semantics of the associated NNPFC SEI message also need to be handled with exceptions. But that aspect is missing.

[0061] Fifth, an example specification for handling of a process chain contains two loops, one loop for the involved SEI messages, and the other loop for the involved pictures, with the latter loop being the inside loop. However, that imposes a delay that is at least equal to the number of the involved pictures. Handling a process chain in the way such that the former loop being the inside loop would solve this problem.

[0062] Sixth, an example specification specifies that, if the decoding system cannot interpret or does not support the functionality indicated by any indicated SEI message that has po_sei_importance_flag[ i ] equal to 1, it should ignore the entire SPO SEI message. However, the operation of the decoding system for the cases of po_sei_importance_flag[ i ] equal to 0 is unspecified. 4. A listing of solutions and embodiments

[0063] To solve the above-described problems, methods as summarized below are disclosed. The aspects should be considered as examples to explain the general concepts and should not be interpreted in a narrow way. Furthermore, these examples can be applied individually or combined in any manner.) In one example, it is specified that processing chains are alternative to each other, i.e., at most one processing chain can be chosen to be applied by a decoding system at one time. ) In one example, a list, e.g., named SpoProcessingList (also known as SpoProcessSeiList), is specified to contain the list of SEI message types implying a process among the SEI message types indicated in an SPO SEI message. ) In one example, the following handling of a processing chain is specified: A decoding system may choose and apply a processing chain as follows: – First, the bitstream is decoded, and the list PoPicList is set to be the list of the cropped decoded pictures in output order that resulted from decoding the bitstream, and a processing chain is chosen. – For each of SEI message types in SpoProcessingList, the following applies in a non-decreasing order of the corresponding po_sei_processing_order[ i ] values: – The following applies for each picture picA in PoPicList in output order, when an SEI message that is associated with the i-th SEI message type persists for picA: – When picA is not a cropped decoded picture, the following exceptions apply for the interpretation of the SEI message: – The interface variables for purposes of interpretation of the SEI message are derived from picA instead of the syntax elements indicating properties for the respective cropped decoded picture. – The semantics of the SEI message, or the semantics of the SEI message and, when the SEI message is an NNPFA SEI message, the associated NNPFC SEI message, apply to pictures in PoPicList instead of cropped decoded pictures. – The process implied by the SEI message type is performed and PoPicList is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process into PoPicList so that the output order is obeyed. NOTE: The corresponding processed picture of a picture may be exactly the same as the picture itself. For example, an input picture to an NNPF may be output by the NNPF without being changed at all, and such an NNPF output picture is still referred to as a processed picture. ) In one example, the following handling of a processing chain is specified: – The following is repeatedly applied, in output order, for each picture picA in PoPicList for which a set of SEI messages associated with SEI message types in SpoProcessingList of the chosen processing chain persist for picA, the following applies: – The following applies for each of the set of SEI messages in a non-decreasing order of the corresponding po_sei_processing_order[ i ] values:– When picA is not a cropped decoded picture, the following exceptions apply for the interpretation of the SEI message: – The interface variables for purposes of interpretation of the SEI message are derived from picA instead of the syntax elements indicating properties for the respective cropped decoded picture. – The semantics of the SEI message, or of the SEI message and, when the SEI message is an NNPFA SEI message, the associated NNPFC SEI message, apply to pictures in PoPicList instead of cropped decoded pictures. – The process implied by the SEI message type is performed and PoPicList is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process into PoPicList so that the output order is obeyed. NOTE: The corresponding processed picture of a picture may be exactly the same as the picture itself. For example, an input picture to an NNPF may be output by the NNPF without being changed at all, and such an NNPF output picture is still referred to as a processed picture. ) In one example, the following handling of a processing chain is specified: – The following is repeatedly applied, in output order, for each picture picA in PoPicList for which a set of SEI messages associated with SEI message types in SpoProcessingList of the chosen processing chain persist for picA, the following applies: – The following applies for each of the set of SEI messages in a non-decreasing order of the corresponding po_sei_processing_order[ i ] values: – When the current SEI message is not the first in the set of the SEI messages, the following exceptions apply for the interpretation of the SEI message: – The interface variables for purposes of interpretation of the SEI message are derived from the pictures in the updated PoPicList instead of the syntax elements indicating properties for the respective cropped decoded pictures. – The semantics of the SEI message, or of the SEI message and, when the SEI message is an NNPFA SEI message, the associated NNPFC SEI message, apply to pictures in PoPicList instead of cropped decoded pictures. – The process implied by the SEI message type is invocated repeatedly for each of the pictures interpolated or extrapolated during the application of the process implied by the previous SEI message, if any, and picA, in output order. After each invocation of the process, PoPicList is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process into PoPicList so that the output order is obeyed.NOTE: The corresponding processed picture of a picture may be exactly the same as the picture itself. For example, an input picture to an NNPF may be output by the NNPF without being changed at all, and such an NNPF output picture is still referred to as a processed picture. 6) In one example, it is specified that, when po_sei_importance_flag[ i ] is equal to 0 for all values of i in the range of 0 to po_num_sei_messages_minus2 + 1, inclusive, and the decoding system cannot interpret or does not support the functionality indicated by any indicated SEI message associated with the loop variable value of i, the decoding system should ignore all data associated with the loop variable value of i. 5. References [1] ITU-T and ISO / IEC, “High efficiency video coding”, Rec. ITU-T H.265 | ISO / IEC 23008-2 (in force edition). [2] ITU-T and ISO / IEC, “Versatile Video Coding”, Rec. ITU-T H.266 | ISO / IEC 23090-3. [3] ITU-T and ISO / IEC, “Versatile Supplemental Enhancement Information Messages for Coded Video Bitstreams”, Rec. ITU-T Rec. H.274 | ISO / IEC 23002-7. [4] G. J. Sullivan, M. M. Hannuksela, and Y.-K. Wang (eds), JVET-AG2027, “SEI processing order and processing order nesting SEI messages in VVC (draft 7)”.

[0064] FIG. 1 is a block diagram showing an example video processing system 4000 in which various techniques disclosed herein may be implemented. Various implementations may include some or all of the components of the system 4000. The system 4000 may include input 4002 for receiving video content. The video content may be received in a raw or uncompressed format, e.g., 8 or 10 bit multi-component pixel values, or may be in a compressed or encoded format. The input 4002 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON), etc. and wireless interfaces such as Wi-Fi or cellular interfaces.

[0065] The system 4000 may include a coding component 4004 that may implement the various coding or encoding methods described in the present document. The coding component 4004 may reduce the average bitrate of video from the input 4002 to the output of the coding component 4004 to produce a coded representation of the video. The coding techniques are therefore sometimes called video compression or video transcoding techniques. The output of the coding component 4004 may be either stored, or transmitted via a communication connected, as represented by the component 4006. The stored or communicated bitstream (or coded) representation of the video received at the input 4002 may be used by a component 4008 for generating pixel values or displayable video that is sent to a display interface 4010. The process of generating user-viewable video from the bitstream representation is sometimes called video decompression. Furthermore, while certain video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by a decoder.

[0066] Examples of a peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HDMI) or Displayport, and so on. Examples of storage interfaces includeserial advanced technology attachment (SATA), peripheral component interconnect (PCI), integrated drive electronics (IDE) interface, and the like. The techniques described in the present document may be embodied in various electronic devices such as mobile phones, laptops, smartphones or other devices that are capable of performing digital data processing and / or video display.

[0067] FIG.2 is a block diagram of an example video processing apparatus 4100. The apparatus 4100 may be used to implement one or more of the methods described herein. The apparatus 4100 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on. The apparatus 4100 may include one or more processors 4102, one or more memories 4104 and video processing circuitry 4106. The processor(s) 4102 may be configured to implement one or more methods described in the present document. The memory (memories) 4104 may be used for storing data and code used for implementing the methods and techniques described herein. The video processing circuitry 4106 may be used to implement, in hardware circuitry, some techniques described in the present document. In some embodiments, the video processing circuitry 4106 may be at least partly included in the processor 4102, e.g., a graphics co-processor.

[0068] FIG.3 is a flowchart for an example method 4200 of video processing. The method 4200 determines to apply processing chains in the alternative such that at most one processing chain can be chosen to be applied by a coding system at one time at step 4202. A conversion between a visual media data and a bitstream is perfomed based on the processing chains at step 4204. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

[0069] It should be noted that the method 4200 can be implemented in an apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, such as video encoder 4400, video decoder 4500, and / or encoder 4600. In such a case, the instructions upon execution by the processor, cause the processor to perform the method 4200. Further, the method 4200 can be performed by a non-transitory computer readable medium comprising a computer program product for use by a video coding device. The computer program product comprises computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method 4200.

[0070] FIG.4 is a block diagram that illustrates an example video coding system 4300 that may utilize the techniques of this disclosure. The video coding system 4300 may include a source device 4310 and a destination device 4320. Source device 4310 generates encoded video data which may be referred to as a video encoding device. Destination device 4320 may decode the encoded video data generated by source device 4310 which may be referred to as a video decoding device.

[0071] Source device 4310 may include a video source 4312, a video encoder 4314, and an input / output (I / O) interface 4316. Video source 4312 may include a source such as a video capture device, an interface to receive video data from a video content provider, and / or a computer graphics system for generating video data, or a combination of such sources. The video data may comprise one or more pictures. Video encoder 4314 encodes the video data from video source 4312 to generate a bitstream. The bitstream may include a sequence of bits that forma coded representation of the video data. The bitstream may include coded pictures and associated data. The coded picture is a coded representation of a picture. The associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. I / O interface 4316 may include a modulator / demodulator (modem) and / or a transmitter. The encoded video data may be transmitted directly to destination device 4320 via I / O interface 4316 through network 4330. The encoded video data may also be stored onto a storage medium / server 4340 for access by destination device 4320.

[0072] Destination device 4320 may include an I / O interface 4326, a video decoder 4324, and a display device 4322. I / O interface 4326 may include a receiver and / or a modem. I / O interface 4326 may acquire encoded video data from the source device 4310 or the storage medium / server 4340. Video decoder 4324 may decode the encoded video data. Display device 4322 may display the decoded video data to a user. Display device 4322 may be integrated with the destination device 4320, or may be external to destination device 4320, which can be configured to interface with an external display device.

[0073] Video encoder 4314 and video decoder 4324 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, Versatile Video Coding (VVM) standard and other current and / or further standards.

[0074] FIG.5 is a block diagram illustrating an example of video encoder 4400, which may be video encoder 4314 in the system 4300 illustrated in FIG.4. Video encoder 4400 may be configured to perform any or all of the techniques of this disclosure. The video encoder 4400 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of video encoder 4400. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

[0075] The functional components of video encoder 4400 may include a partition unit 4401, a prediction unit 4402 which may include a mode select unit 4403, a motion estimation unit 4404, a motion compensation unit 4405, an intra prediction unit 4406, a residual generation unit 4407, a transform processing unit 4408, a quantization unit 4409, an inverse quantization unit 4410, an inverse transform unit 4411, a reconstruction unit 4412, a buffer 4413, and an entropy encoding unit 4414.

[0076] In other examples, video encoder 4400 may include more, fewer, or different functional components. In an example, prediction unit 4402 may include an intra block copy (IBC) unit. The IBC unit may perform prediction in an IBC mode in which at least one reference picture is a picture where the current video block is located.

[0077] Furthermore, some components, such as motion estimation unit 4404 and motion compensation unit 4405 may be highly integrated, but are represented in the example of video encoder 4400 separately for purposes of explanation.

[0078] Partition unit 4401 may partition a picture into one or more video blocks. Video encoder 4400 and video decoder 4500 may support various video block sizes.

[0079] Mode select unit 4403 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra or inter coded block to a residual generation unit 4407 to generate residual block data and to a reconstruction unit 4412 to reconstruct the encoded block for use as a reference picture. In some examples, mode select unit 4403 may select a combination of intra and inter prediction (CIIP) mode in which the prediction is based on an inter prediction signal and an intra prediction signal. Mode select unit 4403 may also select a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter prediction.

[0080] To perform inter prediction on a current video block, motion estimation unit 4404 may generate motion information for the current video block by comparing one or more reference frames from buffer 4413 to the current video block. Motion compensation unit 4405 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 4413 other than the picture associated with the current video block.

[0081] Motion estimation unit 4404 and motion compensation unit 4405 may perform different operations for a current video block, for example, depending on whether the current video block is in an I slice, a P slice, or a B slice.

[0082] In some examples, motion estimation unit 4404 may perform uni-directional prediction for the current video block, and motion estimation unit 4404 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. Motion estimation unit 4404 may then generate a reference index that indicates the reference picture in list 0 or list 1 that contains the reference video block and a motion vector that indicates a spatial displacement between the current video block and the reference video block. Motion estimation unit 4404 may output the reference index, a prediction direction indicator, and the motion vector as the motion information of the current video block. Motion compensation unit 4405 may generate the predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.

[0083] In other examples, motion estimation unit 4404 may perform bi-directional prediction for the current video block, motion estimation unit 4404 may search the reference pictures in list 0 for a reference video block for the current video block and may also search the reference pictures in list 1 for another reference video block for the current video block. Motion estimation unit 4404 may then generate reference indexes that indicate the reference pictures in list 0 and list 1 containing the reference video blocks and motion vectors that indicate spatial displacements between the reference video blocks and the current video block. Motion estimation unit 4404 may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. Motion compensation unit 4405 may generate the predicted video block of the current video block based on the reference video blocks indicated by the motion information of the current video block.

[0084] In some examples, motion estimation unit 4404 may output a full set of motion information for decoding processing of a decoder. In some examples, motion estimation unit 4404 may not output a full set of motion information for the current video. Rather, motion estimation unit 4404 may signal the motion informationof the current video block with reference to the motion information of another video block. For example, motion estimation unit 4404 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block.

[0085] In one example, motion estimation unit 4404 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 4500 that the current video block has the same motion information as another video block.

[0086] In another example, motion estimation unit 4404 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD). The motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 4500 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0087] As discussed above, video encoder 4400 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder 4400 include advanced motion vector prediction (AMVP) and merge mode signaling.

[0088] Intra prediction unit 4406 may perform intra prediction on the current video block. When intra prediction unit 4406 performs intra prediction on the current video block, intra prediction unit 4406 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture. The prediction data for the current video block may include a predicted video block and various syntax elements.

[0089] Residual generation unit 4407 may generate residual data for the current video block by subtracting the predicted video block(s) of the current video block from the current video block. The residual data of the current video block may include residual video blocks that correspond to different sample components of the samples in the current video block.

[0090] In other examples, there may be no residual data for the current video block for the current video block, for example in a skip mode, and residual generation unit 4407 may not perform the subtracting operation.

[0091] Transform processing unit 4408 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.

[0092] After transform processing unit 4408 generates a transform coefficient video block associated with the current video block, quantization unit 4409 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.

[0093] Inverse quantization unit 4410 and inverse transform unit 4411 may apply inverse quantization and inverse transforms to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block. Reconstruction unit 4412 may add the reconstructed residual video block tocorresponding samples from one or more predicted video blocks generated by the prediction unit 4402 to produce a reconstructed video block associated with the current block for storage in the buffer 4413.

[0094] After reconstruction unit 4412 reconstructs the video block, the loop filtering operation may be performed to reduce video blocking artifacts in the video block.

[0095] Entropy encoding unit 4414 may receive data from other functional components of the video encoder 4400. When entropy encoding unit 4414 receives the data, entropy encoding unit 4414 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.

[0096] FIG.6 is a block diagram illustrating an example of video decoder 4500 which may be video decoder 4324 in the system 4300 illustrated in FIG.4. The video decoder 4500 may be configured to perform any or all of the techniques of this disclosure. In the example shown, the video decoder 4500 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of the video decoder 4500. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

[0097] In the example shown, video decoder 4500 includes an entropy decoding unit 4501, a motion compensation unit 4502, an intra prediction unit 4503, an inverse quantization unit 4504, an inverse transformation unit 4505, a reconstruction unit 4506, and a buffer 4507. Video decoder 4500 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 4400.

[0098] Entropy decoding unit 4501 may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data). Entropy decoding unit 4501 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 4502 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 4502 may, for example, determine such information by performing the AMVP and merge mode.

[0099] Motion compensation unit 4502 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.

[0100] Motion compensation unit 4502 may use interpolation filters as used by video encoder 4400 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 4502 may determine the interpolation filters used by video encoder 4400 according to received syntax information and use the interpolation filters to produce predictive blocks.

[0101] Motion compensation unit 4502 may use some of the syntax information to determine sizes of blocks used to encode frame(s) and / or slice(s) of the encoded video sequence, partition information that describes how each macroblock of a picture of the encoded video sequence is partitioned, modes indicating how each partition isencoded, one or more reference frames (and reference frame lists) for each inter coded block, and other information to decode the encoded video sequence.

[0102] Intra prediction unit 4503 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit 4504 inverse quantizes, i.e., de- quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 4501. Inverse transform unit 4505 applies an inverse transform.

[0103] Reconstruction unit 4506 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 4502 or intra prediction unit 4503 to form decoded blocks. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts. The decoded video blocks are then stored in buffer 4507, which provides reference blocks for subsequent motion compensation / intra prediction and also produces decoded video for presentation on a display device.

[0104] FIG. 7 is a schematic diagram of an example encoder 4600. The encoder 4600 is suitable for implementing the techniques of VVC. The encoder 4600 includes three in-loop filters, namely a deblocking filter (DF) 4602, a sample adaptive offset (SAO) 4604, and an adaptive loop filter (ALF) 4606. Unlike the DF 4602, which uses predefined filters, the SAO 4604 and the ALF 4606 utilize the original samples of the current picture to reduce the mean square errors between the original samples and the reconstructed samples by adding an offset and by applying a finite impulse response (FIR) filter, respectively, with coded side information signaling the offsets and filter coefficients. The ALF 4606 is located at the last processing stage of each picture and can be regarded as a tool trying to catch and fix artifacts created by the previous stages.

[0105] The encoder 4600 further includes an intra prediction component 4608 and a motion estimation / compensation (ME / MC) component 4610 configured to receive input video. The intra prediction component 4608 is configured to perform intra prediction, while the ME / MC component 4610 is configured to utilize reference pictures obtained from a reference picture buffer 4612 to perform inter prediction. Residual blocks from inter prediction or intra prediction are fed into a transform (T) component 4614 and a quantization (Q) component 4616 to generate quantized residual transform coefficients, which are fed into an entropy coding component 4618. The entropy coding component 4618 entropy codes the prediction results and the quantized transform coefficients and transmits the same toward a video decoder (not shown). Quantization components output from the quantization component 4616 may be fed into an inverse quantization (IQ) components 4620, an inverse transform component 4622, and a reconstruction (REC) component 4624. The REC component 4624 is able to output images to the DF 4602, the SAO 4604, and the ALF 4606 for filtering prior to those images being stored in the reference picture buffer 4612.

[0106] FIG.8 is a flowchart for an example method 4700 of video processing. The method 4700 determines to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list at step 4702. A conversion between a visual media data and a bitstream is perfomed based on the processingchain at step 4704. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

[0107] It should be noted that the method 4700 can be implemented in an apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, such as video encoder 4400, video decoder 4500, and / or encoder 4600. In such a case, the instructions upon execution by the processor, cause the processor to perform the method 4700. Further, the method 4700 can be performed by a non-transitory computer readable medium comprising a computer program product for use by a video coding device. The computer program product comprises computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method 4700.

[0108] A listing of solutions preferred by some examples is provided next.

[0109] The following solutions show examples of techniques discussed herein.

[0110] 1. A method for processing media data comprising: determining to apply processing chains in the alternative such that at most one processing chain can be chosen to be applied by a coding system at one time; and performing a conversion between a visual media data and a bitstream based on the processing chains.

[0111] 2. The method of solution 1, wherein a list contains supplemental enhancement information (SEI) message types implying a process among the SEI message types indicated in an SEI processing order (SPO) SEI message.

[0112] 3. The method of any of solutions 1-2, wherein the list is a SpoProcessingList.

[0113] 4. The method of any of solutions 1-3, wherein a decoding system may choose and apply a processing chain as follows: the bitstream is decoded, the list PoPicList is set to be the list of the cropped decoded pictures in output order that resulted from decoding the bitstream, and a processing chain is chosen; for each of SEI message types in SpoProcessingList, the following applies in a non-decreasing order of the corresponding po_sei_processing_order[ i ] values: the following applies for each picture picA in PoPicList in output order, when an SEI message that is associated with the i-th SEI message type persists for picA: when picA is not a cropped decoded picture, the following exceptions apply for the interpretation of the SEI message: the interface variables for purposes of interpretation of the SEI message are derived from picA instead of the syntax elements indicating properties for the respective cropped decoded picture, the semantics of the SEI message, or the semantics of the SEI message and, when the SEI message is an NNPFA SEI message, the associated NNPFC SEI message, apply to pictures in PoPicList instead of cropped decoded pictures, the process implied by the SEI message type is performed and PoPicList is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process into PoPicList so that the output order is obeyed, wherein the corresponding processed picture of a picture may be exactly the same as the picture itself, or wherein an input picture to an NNPF may be output by the NNPF without being changed at all, and such an NNPF output picture is still referred to as a processed picture.

[0114] 5. The method of any of solutions 1-4, wherein the following is repeatedly applied, in output order, for each picture picA in PoPicList for which a set of SEI messages associated with SEI message types in SpoProcessingList of the chosen processing chain persist for picA, the following applies: the following applies for each of the set of SEI messages in a non-decreasing order of the corresponding po_sei_processing_order[ i ] values: when picA is not a cropped decoded picture, the following exceptions apply for the interpretation of the SEI message: the interface variables for purposes of interpretation of the SEI message are derived from picA instead of the syntax elements indicating properties for the respective cropped decoded picture, the semantics of the SEI message, or of the SEI message and, when the SEI message is an NNPFA SEI message, the associated NNPFC SEI message, apply to pictures in PoPicList instead of cropped decoded pictures, the process implied by the SEI message type is performed and PoPicList is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process into PoPicList so that the output order is obeyed, wherein the corresponding processed picture of a picture may be exactly the same as the picture itself, or wherein an input picture to an NNPF may be output by the NNPF without being changed at all, and such an NNPF output picture is still referred to as a processed picture.

[0115] 6. The method of any of solutions 1-5, wherein the following is repeatedly applied, in output order, for each picture picA in PoPicList for which a set of SEI messages associated with SEI message types in SpoProcessingList of the chosen processing chain persist for picA, the following applies: the following applies for each of the set of SEI messages in a non-decreasing order of the corresponding po_sei_processing_order[ i ] values: when the current SEI message is not the first in the set of the SEI messages, the following exceptions apply for the interpretation of the SEI message: the interface variables for purposes of interpretation of the SEI message are derived from the pictures in the updated PoPicList instead of the syntax elements indicating properties for the respective cropped decoded pictures, the semantics of the SEI message, or of the SEI message and, when the SEI message is an NNPFA SEI message, the associated NNPFC SEI message, apply to pictures in PoPicList instead of cropped decoded pictures, the process implied by the SEI message type is invocated repeatedly for each of the pictures interpolated or extrapolated during the application of the process implied by the previous SEI message, if any, and picA, in output order, wherein after each invocation of the process, PoPicList is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process into PoPicList so that the output order is obeyed, wherein the corresponding processed picture of a picture may be exactly the same as the picture itself, or wherein an input picture to an NNPF may be output by the NNPF without being changed at all, and such an NNPF output picture is still referred to as a processed picture.

[0116] 7. The method of any of solutions 1-6, wherein the conversion includes encoding the visual media data into the bitstream.

[0117] 8. The method of any of solutions 1-7, wherein the conversion includes decoding the visual media data from the bitstream.

[0118] 9. An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of solutions 1-8.

[0119] 10. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of solutions 1-9.

[0120] 11. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining to apply processing chains in the alternative such that at most one processing chain can be chosen to be applied by a coding system at one time; and generating a bitstream based on the determining.

[0121] 12. A method for storing bitstream of a video comprising: determining to apply processing chains in the alternative such that at most one processing chain can be chosen to be applied by a coding system at one time; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

[0122] 13. A method, apparatus, or system described in the present document.

[0123] The following solutions show further examples of techniques discussed herein.

[0124] 1. A method for processing visual media data comprising: determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; and performing a conversion between a visual media data and a bitstream based on the processing chain.

[0125] 2. The method of solution 1, wherein handling the processing chain comprises repeatedly applying, in output order, a set of SEI messages for each current picture (picA) in a processing order picture list (PoPicList) for which the set of SEI messages associated with SEI message types in SEI processing order (SPO) processing list (SpoProcessingList) of a chosen processing chain persist for picA.

[0126] 3. The method of any of solutions 1-2, wherein each of the set of SEI messages are applied in a non- decreasing order of corresponding ith processing order SEI processing order (po_sei_processing_order[ i ]) values.

[0127] 4. The method of any of solutions 1-3, wherein exceptions apply for an interpretation of a current SEI message when the current SEI message is not a first in the set of the SEI messages.

[0128] 5. The method of any of solutions 1-4, wherein interface variables for interpretation of the current SEI message are derived from pictures in an updated PoPicList instead of syntax elements indicating properties for respective cropped decoded pictures.

[0129] 6. The method of any of solutions 1-5, wherein semantics of the current SEI message apply to pictures in PoPicList instead of applying to cropped decoded pictures.

[0130] 7. The method of any of solutions 1-6, wherein when the current SEI message is a neural-network post-filter activation (NNPFA) SEI message, semantics of an associated neural-network post-filter characteristics (NNPFC) SEI message apply to the pictures in PoPicList instead of applying to the cropped decoded pictures.

[0131] 8. The method of any of solutions 1-7, wherein a process implied by an SEI message type is invocated repeatedly for each picture interpolated or extrapolated during application of a process implied by a previous SEI message, and for picA, in output order, and wherein after each invocation of the process, PoPicList is updated by replacing pictures with corresponding processed pictures resulting from the process and inserting other pictures resulting from the process into PoPicList so that an output order is obeyed.

[0132] 9. The method of any of solutions 1-8, wherein a corresponding processed picture of a picture is exactly the same as the picture.

[0133] 10. The method of any of solutions 1-9, wherein an input picture to a neural-network post-filter (NNPF) is output by the NNPF as an NNPF output picture without being changed, and wherein the NNPF output picture is referred to as a processed picture.

[0134] 11. The method of any of solutions 1-10, wherein exceptions apply for an interpretation of a current SEI message when picA is not a cropped decoded picture.

[0135] 12. The method of any of solutions 1-11, wherein interface variables for interpretation of the current SEI message are derived from picA instead of syntax elements indicating properties for respective cropped decoded pictures.

[0136] 13. The method of any of solutions 1-12, wherein a process implied by an SEI message type is performed and PoPicList is updated by replacing pictures with corresponding processed pictures resulting from the process and inserting other pictures resulting from the process into PoPicList so that an output order is obeyed.

[0137] 14. The method of any of solutions 1-13, wherein when an ith processing order SEI importance flag (po_sei_importance_flag[ i ]) is equal to 0 for all values of i in a range of 0 to processing order number of SEI messages minus 2 (po_num_sei_messages_minus2) + 1, inclusive, and when a decoding system cannot interpret or does not support a functionality indicated by any SEI message associated with a loop variable value of i, the decoding system should ignore all data associated with the loop variable value of i.

[0138] 15. The method of any of solutions 1-14, wherein the conversion includes encoding the visual media data into the bitstream.

[0139] 16. The method of any of solutions 1-14, wherein the conversion includes decoding the visual media data from the bitstream.

[0140] 17. An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of solutions 1-16.

[0141] 18. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on thenon-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of solutions 1-16.

[0142] 19. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; and generating a bitstream based on the determining.

[0143] 20. A method for storing bitstream of a video comprising: determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

[0144] In the solutions described herein, an encoder may conform to the format rule by producing a coded representation according to the format rule. In the solutions described herein, a decoder may use the format rule to parse syntax elements in the coded representation with the knowledge of presence and absence of syntax elements according to the format rule to produce decoded video.

[0145] In the present document, the term “video processing” may refer to video encoding, video decoding, video compression or video decompression. For example, video compression algorithms may be applied during conversion from pixel representation of a video to a corresponding bitstream representation or vice versa. The bitstream representation of a current video block may, for example, correspond to bits that are either co-located or spread in different places within the bitstream, as is defined by the syntax. For example, a macroblock may be encoded in terms of transformed and coded error residual values and also using bits in headers and other fields in the bitstream. Furthermore, during conversion, a decoder may parse a bitstream with the knowledge that some fields may be present, or absent, based on the determination, as is described in the above solutions. Similarly, an encoder may determine that certain syntax fields are or are not to be included and generate the coded representation accordingly by including or excluding the syntax fields from the coded representation.

[0146] The disclosed and other solutions, examples, embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include,in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine- generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.

[0147] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0148] The processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[0149] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and compact disc read-only memory (CD ROM) and Digital versatile disc-read only memory (DVD-ROM) disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0150] While this patent document contains many specifics, these should not be construed as limitations on the scope of any subject matter or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular techniques. Certain features that are described in this patent document inthe context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0151] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

[0152] Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.

[0153] A first component is directly coupled to a second component when there are no intervening components, except for a line, a trace, or another medium between the first component and the second component. The first component is indirectly coupled to the second component when there are intervening components other than a line, a trace, or another medium between the first component and the second component. The term “coupled” and its variants include both directly coupled and indirectly coupled. The use of the term “about” means a range including ±10% of the subsequent number unless otherwise stated.

[0154] While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.

[0155] In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled may be directly connected or may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

CLAIMS What is claimed is:

1. A method for processing visual media data comprising: determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; and performing a conversion between a visual media data and a bitstream based on the processing chain.

2. The method of claim 1, wherein handling the processing chain comprises repeatedly applying, in output order, a set of SEI messages for each current picture (picA) in a processing order picture list (PoPicList) for which the set of SEI messages associated with SEI message types in SEI processing order (SPO) processing list (SpoProcessingList) of a chosen processing chain persist for picA.

3. The method of any of claims 1-2, wherein each of the set of SEI messages are applied in a non-decreasing order of corresponding ith processing order SEI processing order (po_sei_processing_order[ i ]) values.

4. The method of any of claims 1-3, wherein exceptions apply for an interpretation of a current SEI message when the current SEI message is not a first in the set of the SEI messages.

5. The method of any of claims 1-4, wherein interface variables for interpretation of the current SEI message are derived from pictures in an updated PoPicList instead of syntax elements indicating properties for respective cropped decoded pictures.

6. The method of any of claims 1-5, wherein semantics of the current SEI message apply to pictures in PoPicList instead of applying to cropped decoded pictures.

7. The method of any of claims 1-6, wherein when the current SEI message is a neural-network post-filter activation (NNPFA) SEI message, semantics of an associated neural-network post-filter characteristics (NNPFC) SEI message apply to the pictures in PoPicList instead of applying to the cropped decoded pictures.

8. The method of any of claims 1-7, wherein a process implied by an SEI message type is invocated repeatedly for each picture interpolated or extrapolated during application of a process implied by a previous SEI message, and for picA, in output order, and wherein after each invocation of the process, PoPicList is updated by replacing pictures with corresponding processed pictures resulting from the process and inserting other pictures resulting from the process into PoPicList so that an output order is obeyed.

9. The method of any of claims 1-8, wherein a corresponding processed picture of a picture is exactly the same as the picture.

10. The method of any of claims 1-9, wherein an input picture to a neural-network post-filter (NNPF) is output by the NNPF as an NNPF output picture without being changed, and wherein the NNPF output picture is referred to as a processed picture.

11. The method of any of claims 1-10, wherein exceptions apply for an interpretation of a current SEI message when picA is not a cropped decoded picture.

12. The method of any of claims 1-11, wherein interface variables for interpretation of the current SEI message are derived from picA instead of syntax elements indicating properties for respective cropped decoded pictures.

13. The method of any of claims 1-12, wherein a process implied by an SEI message type is performed and PoPicList is updated by replacing pictures with corresponding processed pictures resulting from the process and inserting other pictures resulting from the process into PoPicList so that an output order is obeyed.

14. The method of any of claims 1-13, wherein when an ith processing order SEI importance flag (po_sei_importance_flag[ i ]) is equal to 0 for all values of i in a range of 0 to processing order number of SEI messages minus 2 (po_num_sei_messages_minus2) + 1, inclusive, and when a decoding system cannot interpret or does not support a functionality indicated by any SEI message associated with a loop variable value of i, the decoding system should ignore all data associated with the loop variable value of i.

15. The method of any of claims 1-14, wherein the conversion includes encoding the visual media data into the bitstream.

16. The method of any of claims 1-14, wherein the conversion includes decoding the visual media data from the bitstream.

17. An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of claims 1-16.

18. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non- transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of claims 1-16.

19. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; and generating a bitstream based on the determining.

20. A method for storing bitstream of a video comprising: determining to handle a processing chain by repeatedly applying each supplemental enhancement information (SEI) message in the processing chain, in increasing order, to each picture, in output order, as contained in a processing order SEI list; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

Images