A method for encoding / decoding video, a method for transmitting a bitstream, and a recording medium for storing a bitstream.

Abstract

A video encoding / decoding method, a bitstream transmission method, and a computer-readable recording medium for storing the bitstream are provided. The video decoding method according to this disclosure includes the steps of acquiring unit information including a current picture and decoding the current picture based on the unit information, wherein the type of the current picture may be restricted based on NNPF (neural-network post-filter) related SEI (supplemental enhancement information) messages included in the unit information.

Description

[Technical Field]

[0001] This disclosure relates to a video encoding / decoding method, a bitstream transmission method, and a recording medium storing a bitstream, and more particularly to a method for processing a neural network postfilter. [Background technology]

[0002] In recent years, demand for high-resolution, high-quality video, such as HD (High Definition) and UHD (Ultra High Definition) video, has been increasing in various fields. The higher the resolution and quality of video data, the greater the amount of information or bits transmitted compared to existing video data. This increase in the amount of information or bits transmitted leads to increased transmission and storage costs.

[0003] Therefore, highly efficient video compression technology is desired to effectively transmit, store, and play back high-resolution, high-quality video information. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The purpose of this disclosure is to provide a video encoding / decoding method and apparatus with improved encoding / decoding efficiency.

[0005] Furthermore, this disclosure aims to provide a video encoding / decoding method and apparatus capable of processing NNPF (neural-network post-filter) related SEI (supplemental enhancement information) messages without errors.

[0006] Furthermore, this disclosure aims to provide a video encoding / decoding method and apparatus that restricts unit information including (composed of; comprising; constructed; configured; set up; encompassing; including; containing; having) NNPFC (neural-network post-filter characteristics) SEI messages so as not to include discardable pictures.

[0007] Furthermore, this disclosure aims to provide a video encoding / decoding method and apparatus in which NNPFC SEI messages are not associated with discardable pictures.

[0008] Furthermore, this disclosure aims to provide a video encoding / decoding method and apparatus that restricts unit information, including NNPFA (neural-network post-filter activation) SEI messages, so as not to include non-output pictures.

[0009] Furthermore, this disclosure aims to provide a video encoding / decoding method and apparatus in which NNPFA SEI messages are not associated with non-output pictures.

[0010] Furthermore, this disclosure aims to provide a video encoding / decoding method and apparatus that prevents mismatches between the input picture list in an encoder and the input picture list in a decoder by ensuring that the input pictures of the NNPF do not include discardable pictures and / or non-output pictures.

[0011] Furthermore, this disclosure aims to provide a non-temporary computer-readable recording medium for storing a bitstream generated by the video encoding method relating to this disclosure.

[0012] Furthermore, this disclosure aims to provide a non-temporary computer-readable recording medium that stores a bitstream that is received and decoded by the video decoding device relating to this disclosure and used for restoring video.

[0013] Also, an object of the present disclosure is to provide a method for transmitting a bitstream generated by the video encoding method according to the present disclosure.

[0014] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those having ordinary knowledge in the technical field to which the present disclosure belongs from the following description.

Means for Solving the Problems

[0015] A video decoding method according to an aspect of the present disclosure is a video decoding method performed by a video decoding apparatus, including a step of acquiring unit information including a current picture, and a step of decoding the current picture based on the unit information, and the type of the current picture may be restricted based on an NNPF-related SEI message included in the unit information.

[0016] A video encoding method according to another aspect of the present disclosure is a video encoding method performed by a video encoding apparatus, including a step of encoding a current picture, and a step of constructing unit information including the encoded current picture, and the type of the current picture may be restricted based on an NNPF-related SEI message included in the unit information.

[0017] A computer-readable recording medium according to still another aspect of the present disclosure can store a bitstream generated by the video encoding method or apparatus of the present disclosure.

[0018] A transmission method according to still another aspect of the present disclosure can transmit a bitstream generated by the video encoding method or apparatus of the present disclosure.

[0019] The features briefly summarized above regarding the present disclosure are merely exemplary aspects of the detailed description of the present disclosure to be described later, and do not limit the scope of the present disclosure.

Advantages of the Invention

[0020] According to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus with improved encoding / decoding efficiency.

[0021] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus that can process NNPF-related SEI messages without errors.

[0022] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus that restricts unit information including NNPFC SEI messages so as not to include disposable pictures.

[0023] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus in which an NNPFC SEI message is not associated with a disposable picture.

[0024] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus that restricts unit information including NNPFA SEI messages so as not to include non-output pictures.

[0025] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus in which an NNPFA SEI message is not associated with a non-output picture.

[0026] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus that prevent a mismatch between an input picture list in an encoder and an input picture list in a decoder by ensuring that an input picture of NNPF does not include a disposable picture and / or a non-output picture.

[0027] Also, according to the present disclosure, it is possible to provide a non-transitory computer-readable recording medium that stores a bitstream generated by the video encoding method according to the present disclosure.

[0028] Furthermore, this disclosure provides a non-temporary computer-readable recording medium for storing a bitstream that is received and decoded by the video decoding device relating to this disclosure and used for restoring video.

[0029] Furthermore, this disclosure provides a method for transmitting a bitstream generated by a video encoding method.

[0030] The effects obtained from this disclosure are not limited to those mentioned above, and any other effects not mentioned above will be clearly understood by a person with ordinary skill in the art to which this disclosure pertains from the following description. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic diagram showing a video coding system to which the embodiments of this disclosure can be applied. [Figure 2] This is a schematic diagram showing a video encoding device to which the embodiments of this disclosure can be applied. [Figure 3] This is a schematic diagram showing an image decoding device to which the embodiments of this disclosure can be applied. [Figure 4] This diagram illustrates the interleaved method for lumen channel induction. [Figure 5] This is a flowchart illustrating a video encoding method to which the embodiments of this disclosure can be applied. [Figure 6] This is a flowchart illustrating a video decoding method to which the embodiments of this disclosure can be applied. [Figure 7] This is a flowchart illustrating other video encoding methods to which the embodiments of this disclosure can be applied. [Figure 8] This is a flowchart illustrating other video decoding methods to which the embodiments of this disclosure can be applied. [Figure 9] This figure illustrates a content streaming system to which the embodiments of this disclosure can be applied. [Modes for carrying out the invention]

[0032] The embodiments of this disclosure are described below in detail with reference to the accompanying drawings, so as to be easily implemented by a person with ordinary skill in the art to which this disclosure pertains. However, this disclosure may be embodied in various other forms and is not limited to the embodiments described herein.

[0033] In describing embodiments of this disclosure, if a specific description of a known configuration or function is deemed to obscure the gist of this disclosure, such detailed description will be omitted. In the figures, parts unrelated to the description of this disclosure will be omitted, and similar parts will be denoted by similar reference numerals.

[0034] In this disclosure, when one component is described as being “linked,” “joined,” or “connected” to another component, this may include not only direct linkages but also indirect linkages where other components exist in between. Furthermore, when one component is described as “containing” or “having” another component, this means, unless otherwise specified, that it may contain further other components rather than excluding them.

[0035] In this disclosure, terms such as "first," "second," etc., are used solely to distinguish one component from another, and do not limit the order or importance of the components unless otherwise specified. Therefore, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0036] In this disclosure, components are distinguished from each other solely to clearly describe their respective characteristics, and this does not necessarily mean that these components are separate. That is, multiple components may be integrated to constitute a single hardware or software unit, or a single component may be distributed to constitute multiple hardware or software units. Therefore, such integrated or distributed embodiments are also included in the scope of this disclosure, even without specific mention.

[0037] In this disclosure, the components described in various embodiments are not necessarily essential components, and some may be optional components. Therefore, embodiments consisting of a subset of the components described in one embodiment are also included in the scope of this disclosure. Furthermore, embodiments that further include other components in addition to the components described in various embodiments are also included in the scope of this disclosure.

[0038] This disclosure relates to the encoding and decoding of video, and unless otherwise defined herein, the terms used herein may have their ordinary meanings in the art to which this disclosure pertains.

[0039] In this disclosure, "picture" generally refers to a unit representing a single video image for a specific time period, and "slice / tile" is an encoding unit that constitutes a part of a picture. A single picture may consist of one or more slices / tiles. A slice / tile may also contain one or more CTUs (coding tree units).

[0040] In this disclosure, “pixel” or “pel” can mean the smallest unit that constitutes a picture (or video). The term “sample” may also be used as a counterpart to pixel. A sample may generally represent a pixel or a pixel value, or it may represent only the pixel / pixel value of the luma component, or only the pixel / pixel value of the chroma component.

[0041] In this disclosure, “unit” may represent a basic unit of image processing. A unit may include at least one of a specific region of a picture and information associated with that region. A unit may, as it may be, be replaced by terms such as “sample array,” “block,” or “area.” In general, an MxN block may include a sample (or sample array) or a set (or array) of transform coefficients consisting of M columns and N rows.

[0042] In this disclosure, “current block” can mean one of the following: “current coding block,” “current coding unit,” “block to encode,” “block to decode,” or “block to process.” When prediction is performed, “current block” can mean “current prediction block” or “block to predict.” When transformation (inverse transformation) / quantization (inverse quantization) is performed, “current block” can mean “current transformation block” or “block to transform.” When filtering is performed, “current block” can mean “block to filter.”

[0043] In this disclosure, "current block" may mean a block containing both a luma component block and a chroma component block, or "the luma block of the current block," unless otherwise explicitly stated as a chroma block. The luma component block of the current block may be expressed with an explicit mention of a luma component block, such as "luma block" or "current luma block." Similarly, the chroma component block of the current block may be expressed with an explicit mention of a chroma component block, such as "chroma block" or "current chroma block."

[0044] In this disclosure, " / " and "," may be interpreted as "and / or." For example, "A / B" and "A, B" may be interpreted as "A and / or B." Also, "A / B / C" and "A, B, C" may mean "at least one of A, B and / or C."

[0045] In this disclosure, “or” may be interpreted as “and / or.” For example, “A or B” may mean 1) “A” only, 2) “B” only, or 3) “A and B.” Alternatively, in this disclosure, “or” may mean “additionally or alternatively.”

[0046] Overview of the video coding system

[0047] Figure 1 is a schematic diagram showing a video coding system to which the embodiments of this disclosure can be applied.

[0048] A video coding system according to one embodiment may include an encoding device 10 and a decoding device 20. The encoding device 10 can transmit encoded video and / or image information or data to the decoding device 20 in file or streaming form via a digital storage medium or network.

[0049] An encoding device 10 according to one embodiment may include a video source generation unit 11, an encoding unit 12, and a transmission unit 13. A decoding device 20 according to one embodiment may include a receiving unit 21, a decoding unit 22, and a rendering unit 23. The encoding unit 12 may be called a video / image encoding unit, and the decoding unit 22 may be called a video / image decoding unit. The transmission unit 13 may be included in the encoding unit 12. The receiving unit 21 may be included in the decoding unit 22. The rendering unit 23 may include a display unit, and the display unit may be composed of a separate device or external component.

[0050] The video source generation unit 11 can acquire video / images through video / image capture, synthesis, or generation processes. The video source generation unit 11 may include a video / image capture device and / or a video / image generation device. The video / image capture device may include, for example, one or more cameras, or a video / image archive containing previously captured video / images. The video / image generation device may include, for example, a computer, a tablet, and a smartphone, and can generate video / images (electronically). For example, virtual video / images may be generated by a computer, in which case the video / image capture process may be replaced by a process in which related data is generated.

[0051] The encoding unit 12 can encode the input video / image data. The encoding unit 12 can perform a series of procedures such as prediction, transformation, and quantization for compression and encoding efficiency. The encoding unit 12 can output the encoded data (encoded video / image information) in the form of a bitstream.

[0052] The transmitting unit 13 can acquire encoded video / image information or data output in bitstream form and transmit it in file or streaming form to the receiving unit 21 of the decoding device 20 or other external object via a digital storage medium or network. The digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray (registered trademark: same hereinafter), HDD, SSD, etc. The transmitting unit 13 may include elements for generating media files in a predetermined file format and may include elements for transmission via a broadcast / communication network. The transmitting unit 13 may be provided as a transmission device separate from the encoding unit 12, in which case the transmission device may include at least one processor that acquires encoded video / image information or data output in bitstream form and a transmitting unit that transmits it in file or streaming form. The receiving unit 21 can extract / receive the bitstream from the storage medium or network and transmit it to the decoding unit 22.

[0053] The decoding unit 22 can decode the video / image by performing a series of procedures such as inverse quantization, inverse transform, and prediction, which correspond to the operation of the encoding unit 12.

[0054] The rendering unit 23 can render the decoded video / image. The rendered video / image may be displayed through the display unit.

[0055] Overview of video encoding equipment

[0056] Figure 2 is a schematic diagram showing a video encoding device to which the embodiments of this disclosure can be applied.

[0057] As shown in Figure 2, the video encoding device 100 may include a video splitting unit 110, a subtraction unit 115, a conversion unit 120, a quantization unit 130, an inverse quantization unit 140, an inverse conversion unit 150, an addition unit 155, a filtering unit 160, a memory 170, an inter-prediction unit 180, an intra-prediction unit 185, and an entropy encoding unit 190. The inter-prediction unit 180 and the intra-prediction unit 185 may be collectively called the "prediction unit". The conversion unit 120, the quantization unit 130, the inverse quantization unit 140, and the inverse conversion unit 150 may be included in the residual processing unit. The residual processing unit may further include a subtraction unit 115.

[0058] Depending on the embodiment, all or at least some of the multiple components constituting the video encoding device 100 may be embodied as a single hardware component (e.g., an encoder or a processor). Furthermore, the memory 170 may include a DPB (decoded picture buffer) and may be embodied by a digital storage medium.

[0059] The video splitting unit 110 can split the input video (or picture, frame) input to the video encoding device 100 into one or more processing units. For example, the processing units may be called coding units (CUs). Coding units can be obtained by recursively splitting a coding tree unit (CTU) or the largest coding unit (LCU) using a QT / BT / TT (Quad-tree / binary-tree / ternary-tree) structure. For example, one coding unit may be split into multiple coding units of deeper depth based on a quad-tree structure, a binary-tree structure, and / or a ternary-tree structure. For the splitting of coding units, a quad-tree structure may be applied first, followed by a binary-tree structure and / or a ternary-tree structure. The coding procedure according to this disclosure may be performed based on the final coding unit that is not further split. The maximum coding unit may be used directly as the final coding unit, or a lower-depth coding unit obtained by dividing the maximum coding unit may be used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and / or restoration, which will be described later. As another example, the processing unit of the coding procedure may be a prediction unit (PU) or a transformation unit (TU). The prediction unit and the transformation unit may be divided or partitioned from the final coding unit, respectively. The prediction unit may be a unit of sample prediction, and the transformation unit may be a unit that derives transformation coefficients and / or a unit that derives a residual signal from transformation coefficients.

[0060] The prediction unit (inter-prediction unit 180 or intra-prediction unit 185) can make predictions for the block to be processed (current block) and generate a predicted block that includes prediction samples for the current block. The prediction unit can determine whether intra-prediction or inter-prediction is applied to the current block or on a CU basis. The prediction unit can generate various information regarding the prediction of the current block and transmit it to the entropy encoding unit 190. The prediction information may be encoded by the entropy encoding unit 190 and output in the form of a bitstream.

[0061] The intra-prediction unit 185 can predict the current block by referring to a sample in the current picture. The referenced sample may be located in the vicinity of the current block or at a distance from it, depending on the intra-prediction mode and / or intra-prediction method. The intra-prediction mode may include a plurality of non-directional modes and a plurality of directional modes. The non-directional modes may include, for example, a DC mode and a planar mode. The directional modes may include, for example, 33 directional prediction modes or 65 directional prediction modes, depending on the accuracy of the prediction direction. However, this is an example, and more or fewer directional prediction modes may be used depending on the settings. The intra-prediction unit 185 can also determine the prediction mode to be applied to the current block using the prediction modes applied to the surrounding blocks.

[0062] The interprediction unit 180 can derive a predicted block relative to the current block based on a reference block (reference sample array) identified by motion vectors on the reference picture. In this case, in order to reduce the amount of motion information transmitted in interprediction mode, motion information can be predicted in units of blocks, subblocks, or samples based on the correlation of motion information between the surrounding blocks and the current block. The motion information may include motion vectors and reference picture indices. The motion information may further include interprediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of interprediction, the surrounding blocks may include spatial neighboring blocks existing in the current picture and temporal neighboring blocks existing in the reference picture. The reference picture containing the reference block and the reference picture containing the temporal neighboring block may be the same or different from each other. The temporal neighboring block may be called a collocated reference block, colCU, etc. The reference picture containing the temporal neighboring block may be called a collocated picture (colPic). For example, the interpretation unit 180 can construct a motion information candidate list based on surrounding blocks and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Interpretation may be performed based on various prediction modes; for example, in skip mode and merge mode, the interpretation unit 180 can use the motion information of surrounding blocks as the motion information of the current block. In skip mode, unlike merge mode, the residual signal does not need to be transmitted.In motion vector prediction (MVP) mode, the motion vectors of surrounding blocks are used as motion vector predictors, and the motion vector of the current block can be signaled by encoding the motion vector difference and an indicator for the motion vector predictor. The motion vector difference represents the difference between the motion vector of the current block and the motion vector predictor.

[0063] The prediction unit can generate a prediction signal based on various prediction methods and / or prediction techniques described later. For example, the prediction unit may apply intra-prediction or inter-prediction to predict the current block, or it may apply intra-prediction and inter-prediction simultaneously. A prediction method that applies intra-prediction and inter-prediction simultaneously to predict the current block may be called CIIP (combined inter and intra prediction). The prediction unit can also perform intra-block copy (IBC) to predict the current block. Intra-block copy may be used, for example, for coding content images / videos such as games, as in SCC (screen content coding). IBC is a method of predicting the current block using a reference block that has already been restored in the current picture at a predetermined distance from the current block. When IBC is applied, the position of the reference block in the current picture may be encoded as a vector (block vector) corresponding to the predetermined distance. IBC basically performs prediction within the current picture, but it may be performed similarly to inter-prediction in that it derives the reference block within the current picture. In other words, IBC can use at least one of the interpretation methods described in this disclosure.

[0064] The predicted signal generated by the prediction unit may be used to generate a restored signal or a residual signal. The subtraction unit 115 can generate a residual signal (residual block, residual sample array) by subtracting the predicted signal output from the prediction unit (predicted block, predicted sample array) from the input video signal (original block, original sample array). The generated residual signal may be transmitted to the conversion unit 120.

[0065] The transformation unit 120 can generate transformation coefficients by applying a transformation method to the residual signal. For example, the transformation method may include at least one of the following: DCT (Discrete Cosine Transform), DST (Discrete Sine Transform), KLT (Karhunen-Loeve Transform), GBT (Graph-Based Transform), or CNT (Conditionally Non-linear Transform). Here, GBT refers to the transformation obtained from a graph when the relationship information between pixels is represented by this graph. CNT refers to the transformation obtained by generating a prediction signal using all previously reconstructed pixels and obtaining a transformation based on it. The transformation process may be applied to pixel blocks of the same size and square shape, or to blocks of a variable size instead of square shape.

[0066] The quantization unit 130 can quantize the conversion coefficients and transmit them to the entropy encoding unit 190. The entropy encoding unit 190 can encode the quantized signal (information about the quantized conversion coefficients) and output it as a bitstream. The information about the quantized conversion coefficients may be called residual information. The quantization unit 130 can rearrange the block-shaped quantized conversion coefficients into a one-dimensional vector form based on the coefficient scan order, and can also generate information about the quantized conversion coefficients based on the one-dimensional vector form of the quantized conversion coefficients.

[0067] The entropy encoding unit 190 can perform various encoding methods, such as exponential Golomb, CAVLC (context-adaptive variable length coding), and CABAC (context-adaptive binary arithmetic coding). In addition to the quantized conversion coefficients, the entropy encoding unit 190 can also encode information necessary for video / image restoration (e.g., the values ​​of syntax elements) together or separately. The encoded information (e.g., encoded video / image information) may be transmitted or stored in the form of a bitstream in units of NAL (network abstraction layer) units. The video / image information may further include information about various parameter sets, such as an adaptation parameter set (APS), picture parameter set (PPS), sequence parameter set (SPS), or video parameter set (VPS). The video / image information may also further include general constraint information. The signaling information, transmitted information, and / or syntax elements referred to in this disclosure may be encoded by the encoding procedure described above and included in the bitstream.

[0068] The bitstream may be transmitted over a network or stored on a digital storage medium. Here, the network may include broadcasting networks and / or communication networks, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. A transmitting unit (not shown) for transmitting the signal output from the entropy encoding unit 190 and / or a storage unit (not shown) for storing it may be provided as an internal / external element of the video encoding device 100, or the transmitting unit may be provided as a component of the entropy encoding unit 190.

[0069] The quantized conversion coefficients output from the quantization unit 130 may be used to generate a resistive signal. For example, by applying inverse quantization and inverse transformation to the quantized conversion coefficients in the inverse quantization unit 140 and the inverse transformation unit 150, a resistive signal (residual block or resistive sample) can be reconstructed.

[0070] The adder 155 can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the reconstructed residual signal to the predicted signal output from the inter-prediction unit 180 or the intra-prediction unit 185. When there is no residual for the block to be processed, such as when skip mode is applied, the predicted block may be used as the reconstructed block. The adder 155 may be called the reconstruction unit or the reconstructed block generation unit. The generated reconstructed signal may be used for intra-prediction of the next block to be processed in the current picture, or, as described later, may be used for inter-prediction of the next picture after filtering.

[0071] The filtering unit 160 can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit 160 can apply various filtering methods to the restored picture to generate a modified restored picture, and store the modified restored picture in the memory 170, specifically in the DPB of the memory 170. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, and bilateral filter. The filtering unit 160 can generate various filtering information and transmit it to the entropy encoding unit 190, as will be described later in the description of each filtering method. The filtering information may be encoded by the entropy encoding unit 190 and output in the form of a bitstream.

[0072] The corrected restored picture transmitted to memory 170 may be used as a reference picture in the interpretation unit 180. This allows the video encoding device 100 to avoid prediction mismatches between the video encoding device 100 and the video decoding device when interpretation is applied, and also improves encoding efficiency.

[0073] The DPB in memory 170 can store the corrected restored picture for use as a reference picture in the inter-prediction unit 180. Memory 170 can store motion information of blocks from which motion information in the current picture has been derived (or encoded) and / or motion information of blocks in the picture that have already been restored. The stored motion information may be transmitted to the inter-prediction unit 180 for use as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. Memory 170 can store restored samples of restored blocks in the current picture and transmit them to the intra-prediction unit 185.

[0074] Overview of the video decoding device

[0075] Figure 3 is a schematic diagram showing an image decoding device to which the embodiments of this disclosure can be applied.

[0076] As shown in Figure 3, the video decoding device 200 may include an entropy decoding unit 210, an inverse quantization unit 220, an inverse transformation unit 230, an addition unit 235, a filtering unit 240, a memory 250, an inter-prediction unit 260, and an intra-prediction unit 265. The inter-prediction unit 260 and the intra-prediction unit 265 can be collectively referred to as the "prediction unit". The inverse quantization unit 220 and the inverse transformation unit 230 may be included in the residual processing unit.

[0077] All or at least some of the multiple components constituting the video decoding device 200 may be embodied as a single hardware component (e.g., a decoder or processor) depending on the embodiment. Furthermore, the memory 170 may include a DPB and may be embodied by a digital storage medium.

[0078] A video decoding device 200 that receives a bitstream containing video / image information can restore the image by performing a process corresponding to the process performed by the video encoding device 100 in Figure 2. For example, the video decoding device 200 can perform decoding using the processing unit applied in the video encoding device. Therefore, the decoding processing unit may be, for example, a coding unit. The coding unit may be a coding tree unit, or it may be obtained by dividing the largest coding unit. The restored video signal decoded and output by the video decoding device 200 may then be played back by a playback device (not shown).

[0079] The video decoding device 200 can receive the signal output from the video encoding device shown in Figure 2 in the form of a bitstream. The received signal may be decoded by the entropy decoding unit 210. For example, the entropy decoding unit 210 can parse the bitstream to derive information necessary for video restoration (or picture restoration) (e.g., video / image information). The video / image information may further include information about various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). The video / image information may also further include general constraint information. The video decoding device may further utilize the parameter set information and / or the general constraint information to decode the video. The signaling information, received information, and / or syntax elements referred to in this disclosure may be obtained from the bitstream by decoding through the decoding procedure. For example, the entropy decoding unit 210 can decode information in the bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and output the values ​​of syntax elements necessary for image restoration and the quantized values ​​of conversion coefficients related to the residual. More specifically, the CABAC entropy decoding method receives bins corresponding to each syntax element in the bitstream, determines a context model using the syntax element information to be decoded and the decoding information of the surrounding blocks and the blocks to be decoded, or symbol / bin information decoded in a previous stage, predicts the probability of bin occurrence based on the determined context model, performs arithmetic decoding of the bins, and generates symbols corresponding to the values ​​of each syntax element.In this case, the CABAC entropy decoding method can update the context model using the decoded symbol / bin information for the context model of the next symbol / bin after determining the context model. Information related to prediction from the information decoded by the entropy decoding unit 210 is provided to the prediction unit (inter-prediction unit 260 and intra-prediction unit 265), and residual values ​​that have been entropy decoded by the entropy decoding unit 210, i.e., quantized conversion coefficients and related parameter information, may be input to the inverse quantization unit 220. In addition, information related to filtering from the information decoded by the entropy decoding unit 210 may be provided to the filtering unit 240. On the other hand, a receiving unit (not shown) that receives signals output from the video encoding device may be further provided as an internal / external element of the video decoding device 200, or the receiving unit may be provided as a component of the entropy decoding unit 210.

[0080] On the other hand, the video decoding device according to this disclosure may be called a video / image / picture decoding device. The video decoding device may include an information decoder (video / image / picture information decoder) and / or a sample decoder (video / image / picture sample decoder). The information decoder may include an entropy decoding unit 210, and the sample decoder may include at least one of an inverse quantization unit 220, an inverse transformation unit 230, an addition unit 235, a filtering unit 240, a memory 250, an inter-prediction unit 260, and an intra-prediction unit 265.

[0081] The inverse quantization unit 220 can inverse quantize the quantized transformation coefficients and output the transformation coefficients. The inverse quantization unit 220 can rearrange the quantized transformation coefficients in a two-dimensional block form. In this case, the rearrangement may be performed based on the coefficient scan order performed by the video encoding device. The inverse quantization unit 220 can perform inverse quantization on the quantized transformation coefficients using quantization parameters (e.g., quantization step size information) and obtain the transformation coefficients.

[0082] The inverse conversion unit 230 can inversely convert the conversion coefficients to obtain residual signals (residual blocks, residual sample arrays).

[0083] The prediction unit can make predictions for the current block and generate a predicted block containing prediction samples for the current block. Based on the prediction information output from the entropy decoding unit 210, the prediction unit can determine whether intra-prediction or inter-prediction is applied to the current block and can determine a specific intra / inter-prediction mode (prediction method).

[0084] As mentioned in the description of the prediction unit of the video coding device 100, the prediction unit can generate prediction signals based on various prediction methods (techniques) described later.

[0085] The intra-prediction unit 265 can predict the current block by referring to the samples in the current picture. The description of the intra-prediction unit 185 may also apply to the intra-prediction unit 265.

[0086] The interprediction unit 260 can derive a predicted block relative to the current block based on a reference block (reference sample array) identified by motion vectors on the reference picture. In this case, in order to reduce the amount of motion information transmitted in interprediction mode, motion information can be predicted in block, subblock, or sample units based on the correlation of motion information between the surrounding block and the current block. The motion information may include motion vectors and reference picture indices. The motion information may further include interprediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of interprediction, the surrounding block may include spatially neighboring blocks present in the current picture and temporally neighboring blocks present in the reference picture. For example, the interprediction unit 260 can construct a motion information candidate list based on the surrounding blocks and derive the motion vector and / or reference picture index of the current block based on the received candidate selection information. Interprediction may be performed based on various prediction modes (methods), and the prediction information may include information indicating the mode (method) of interprediction for the current block.

[0087] The adder 235 can generate a restored signal (restored picture, restored block, restored sample array) by adding the acquired residual signal to the predicted signal (predicted block, predicted sample array) output from the prediction unit (including the inter-prediction unit 260 and / or intra-prediction unit 265). When there is no residual for the block to be processed, such as when skip mode is applied, the predicted block may be used as the restored block. The description of the adder 155 may also apply to the adder 235. The adder 235 may be called the restore unit or the restored block generation unit. The generated restored signal may be used for intra-prediction of the next block to be processed in the current picture, or, as described later, may be used for inter-prediction of the next picture after filtering.

[0088] The filtering unit 240 can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit 240 can apply various filtering methods to the restored picture to generate a modified restored picture, and the modified restored picture can be stored in the memory 250, specifically in the DPB of the memory 250. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, and bilateral filter.

[0089] The restored picture stored (modified) in the DPB of memory 250 may be used as a reference picture in the inter-prediction unit 260. Memory 250 can store motion information of blocks from which motion information in the current picture has been derived (or decoded) and / or motion information of blocks in the picture that have already been restored. The stored motion information can be transmitted to the inter-prediction unit 260 for use as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. Memory 250 can store restored samples of restored blocks in the current picture and transmit them to the intra-prediction unit 265.

[0090] In this specification, the embodiments described for the filtering unit 160, inter-prediction unit 180, and intra-prediction unit 185 of the video encoding device 100 may be applied identically or in a corresponding manner to the filtering unit 240, inter-prediction unit 260, and intra-prediction unit 265 of the video decoding device 200, respectively.

[0091] Neural network post-filter characteristics (NNPFC)

[0092] The combinations in Tables 1 to 3 represent the NNPFC syntax structure.

[0093] [Table 1]

[0094] [Table 2]

[0095] [Table 3]

[0096] The NNPFC syntax structures shown in Tables 1 to 3 may be signaled in the form of SEI (supplemental enhancement information) messages. SEI messages that signal the NNPFC syntax structures shown in Tables 1 to 3 can be called NNPFC SEI messages.

[0097] NNPFC SEI messages can identify neural networks available as post-processing filters. The use of identified post-processing filters for a particular picture can be indicated using neural-network post-filter activation (NNPFA) SEI messages. Here, "post-processing filter" and "post-filter" may have the same meaning.

[0098] To use such SEI messages, you may need to define variables like the following:

[0099] - The width and height of the input picture may be cropped in lumen samples, and these widths and heights can be represented by CroppedWidth and CroppedHeight, respectively.

[0100] - The lumens sample array of the input picture, CroppedYPic[idx], and the chromens sample arrays, CroppedCbPic[idx] and CroppedCrPic[idx], may be used as input to the NNPF if they exist, and the index idx may be in the range of 0 to numInputPics-1.

[0101] - BitDepth Y This can show the bit depth of the input picture relative to the lumens sample array.

[0102] - BitDepth C This can show the bit depth of the chroma sample array (if any) of the input picture.

[0103] - ChromaFormatIdc can indicate a chroma format identifier.

[0104] - If the value of nnpfc_auxiliary_inp_idc is 1, the filtering strength control value StrengthControlVal must be a real number in the range of 0 to 1.

[0105] An input picture with index 0 may be a picture whose NNPF, defined by an NNPFC SEI message, has been activated by an NNPFA SEI message. An input picture whose index i is within the range of 1 to numInputPics-1 may take precedence over an input picture with index i-1 in the output order.

[0106] If nnpfc_purpose & 0x08 is not identical to 0, and an input picture with index 0 is associated with a frame packing array SEI message having the same fp_arrangement_type as 5, then all input pictures may be associated with a frame packing array SEI message having the same fp_arrangement_type as 5, and may have the same value as fp_current_frame_is_frame0_flag.

[0107] There may be two or more NNPFC SEI messages for the same picture. If two or more NNPFC SEI messages with different nnpfc_id values ​​exist or are activated for the same picture, the two or more NNPFC SEI messages may have the same or different nnpfc_purpose and nnpfc_mode_idc values.

[0108] nnpfc_purpose can indicate the purpose of the NNPF as shown in Table 4. The value of nnpfc_purpose may be restricted to being within the range of 0 to 63 in the bitstream. Values ​​for nnpfc_purpose in the range of 64 to 65535 may be reserved for future use. The decoder must ignore NNPFC SEI messages with nnpfc_purpose in the range of 64 to 65535. If a value of nnpfc_purpose is reserved for future use, the syntax elements of this SEI message may be extended to syntax elements that exist on the condition that nnpfc_purpose is identical to that value. If ChromaFormatIdc is identical to 3, then nnpfc_purpose & 0x02 must be identical to 0. If ChromaFormatIdc or nnpfc_purpose & 0x02 is not identical to 0, then nnpfc_purpose & 0x20 must be identical to 0.

[0109] [Table 4]

[0110] nnpfc_id may contain an identification number that can be used to identify NNPF. The nnpfc_id value is between 0 and 2 32 It must be within the range of -2. The range is 256~511 and 2 31 ~2 32 -2 range nnpfc_id values ​​may be reserved for future use. Decoders are in the range of 256~511 or 2 31 ~2 32 NNPFC SEI messages with an nnpfc_id in the -2 range must be ignored.

[0111] If an NNPFC SEI message is currently the first NNPFC SEI message in the decoding sequence that has a specific nnpfc_id value within CLVS, the following may apply:

[0112] - The aforementioned SEI message can indicate base NNPF.

[0113] - The SEI message may be associated in output order with the currently decoded picture and all subsequent decoded pictures of the current layer until the CLVS finishes.

[0114] An NNPFC SEI message may be a repetition of a previous NNPFC SEI message in the CLVS in the decoding order, and the subsequent semantics may be applied as if this SEI message were the only NNPFC SEI message in the CLVS that has the same content.

[0115] A value of 0 for nnpfc_mode_idc indicates that the SEI message contains a bitstream representing the basic NNPF, or that it represents an update related to the basic NNPF having the same nnpfc_id value.

[0116] If an NNPFC SEI message is the first NNPFC SEI message in a decoding sequence currently having a specific nnpfc_id value within the CLVS, a value of 1 for nnpfc_mode_idc may indicate that the basic NNPF associated with the nnpfc_id value is a neural network, and the neural network may be identified by a URI represented by nnpfc_uri using the format identified by the tag URI nnpfc_tag_uri.

[0117] If an NNPFC SEI message is neither the first NNPFC SEI message in a decoding sequence currently having a specific nnpfc_id value within the CLVS, nor a repetition of the first NNPFC SEI message, then a value of 1 for nnpfc_mode_idc may indicate that an update related to the underlying NNPF having the same nnpfc_id value is defined by a URI represented by nnpfc_uri using the tag URI nnpfc_tag_uri.

[0118] The value of nnpfc_mode_idc may be restricted to being in the range of 0 to 1 in the bitstream. Values ​​in the range of 2 to 255 for nnpfc_mode_idc may be reserved for future use and do not need to be present in the bitstream. The decoder must ignore NNPFC SEI messages with nnpfc_mode_idc in the range of 2 to 255. Values ​​of nnpfc_mode_idc greater than 255 do not need to be present in the bitstream and do not need to be reserved for future use.

[0119] If the aforementioned SEI message is the first NNPFC SEI message in the decoding order that currently has a specific nnpfc_id value within CLVS, then the NNPF PostProcessingFilter() may be assigned the same as the basic NNPF.

[0120] If the aforementioned SEI message is not the first NNPFC SEI message in the decoding sequence currently having a specific nnpfc_id value within CLVS, nor is it an iteration of the first NNPFC SEI message, then the NNPF PostProcessingFilter() may apply the update defined by the SEI message to the base NNPF and retrieve it.

[0121] Updates are not cumulative; rather, each update may be applied to the base NNPF which is the NNPF specified by the first NNPFC SEI message in the decoding order that currently has a specific nnpfc_id value within CLVS.

[0122] nnpfc_reserved_zero_bit_a may be restricted to have the same value as 0 by bitstream restrictions. The decoder may be restricted to ignore NNPFC SEI messages where the value of nnpfc_reserved_zero_bit_a is not 0.

[0123] The nnpfc_tag_uri may contain a tag URI having syntax and semantics specified in IETF RFC 4151 that identifies the neural network used as the base NNPF or an update to the base NNPF using the nnpfc_id value identified by the nnpfc_uri. Using nnpfc_tag_uri, the format of the neural network data specified by nnrpf_uri can be uniquely identified without a central registration authority. The same nnpfc_tag_uri as "tag:iso.org,2023:15938-17" can indicate that the neural network data identified by nnpfc_uri complies with ISO / IEC 15938-17.

[0124] nnpfc_uri may contain a URI having syntax and semantics specified in IETF Internet Standard 66 that identifies a neural network used as a base NNPF or an update associated with a base NNPF that uses the same nnpfc_id value.

[0125] A value of 1 for nnpfc_property_present_flag can indicate the presence of syntax elements related to the filter's purpose, input formatting, output formatting, and complexity. A value of 0 for nnpfc_property_present_flag can indicate the absence of syntax elements related to the filter's purpose, input formatting, output formatting, and complexity. The value of nnpfc_property_present_flag may be restricted to being identical to 1 if the SEI message is the first NNPFC SEI message in the decoding order and currently has a specific nnpfc_id value in CLVS. When the value of nnpfc_property_present_flag is identical to 0, the values ​​of all syntax elements that exist only when the value of nnpfc_property_present_flag is 1 and for which no inferred value has been specified may be inferred to be identical to the corresponding syntax elements in the NNPFC SEI message containing the base NNPF for which the SEI provides updates.

[0126] A value of 1 for nnpfc_base_flag indicates that the SEI message is a basic NNPF. A value of 0 for nnpfc_base_flag indicates that the SEI message is an update related to a basic NNPF. If nnpfc_base_flag is not present, its value can be inferred to be 0.

[0127] The following restrictions may apply to the value of nnpfc_base_flag:

[0128] - If an NNPFC SEI message is the first NNPFC SEI message in the CLVS that currently has a specific nnpfc_id value in the decoding order, the value of nnpfc_base_flag may be the same as 1.

[0129] - If NNPFC SEI message nnpfcB is not the first NNPFC SEI message in the CLVS that currently has a specific nnpfc_id value in the decoding order, and the value of nnpfc_base_flag is the same as 1, then the NNPFC SEI message may be a repetition of the first NNPFC SEI message nnpfcA that has the same nnpfc_id in the decoding order. That is, the payload condensates of nnpfcB may be the same as the payload condensates of nnpfcA.

[0130] The following may apply if an NNPFC SEI message is not the first NNPFC SEI message with a specific nnpfc_id value in the CLVS in the decoding order, and does not correspond to an iteration of the first NNPFC SEI message with a specific nnpfc_id value.

[0131] - SEI messages can define updates related to the preceding basic NNPF that have the same nnpfc_id value and are in the decoding order.

[0132] - SEI messages are related in output order to the current restored picture of the current layer and all subsequent restored pictures, up to the end of the current CLVS or up to the next restored picture after the current restored picture within the current CLVS, and in decoding order to subsequent NNPFC SEI messages that have an earlier value among the specific nnpfc_id values ​​within the current CLVS.

[0133] The following restrictions may apply if an NNPFC SEI message nnpfcCurr is not the first NNPFC SEI message in the CLVS that currently has a specific nnpfc_id value in the decoding order, nor is it an iteration of the first NNPFC SEI message that has a specific nnpfc_id value (i.e., the value of nnpfc_base_flag is 0), and the value of nnpfc_property_present_flag is 1.

[0134] - The value of nnpfc_purpose in an NNPFC SEI message must be identical to the value of nnpfc_purpose in the first NNPFC SEI message that currently has a specific nnpfc_id value in the CLVS in the decoding order.

[0135] - The values ​​of the syntax elements nnpfc_base_flag and preceding nnpfc_complexity_info_present_flag within an NNPFC SEI message must be identical to the values ​​of the corresponding syntax elements in the first NNPFC SEI message that currently has a specific nnpfc_id value in the CLVS in the decoding order.

[0136] - In the decoding order, the nnpfc_complexity_info_present_flag in the first NNPFC SEI message that currently has a specific nnpfc_id value in CLVS must be equal to 0, or both must be equal to 1, and the following may apply:

[0137] (1) The nnpfc_parameter_parameter_type_idc in nnpfcCurr must be identical to the nnpfc_parameter_parameter_type_idc in nnpfcBase.

[0138] (2) If nnpfc_log2_parameter_bit_length_minus3 exists in nnpfcCurr, then nnpfc_log2_parameter_bit_length_minus3 in nnpfcCurr must be less than or equal to nnpfc_log2_parameter_bit_length_minus3 in nnpfcBase.

[0139] (3) If nnpfc_num_parameters_idc in nnpfcBase is the same as 0, then nnpfc_num_parameters_idc in nnpfcCurr must also be the same as 0.

[0140] (4) Otherwise (if nnpfc_num_parameters_idc in nnpfcBase is greater than 0), then nnpfc_num_parameters_idc in nnpfcCurr must be greater than 0 or less than or equal to nnpfc_num_parameters_idc in nnpfcBase.

[0141] (5) If nnpfc_num_kmac_operations_idc in nnpfcBase is the same as 0, then nnpfc_num_kmac_operations_idc in nnpfcCurr must also be the same as 0.

[0142] (6) If not (where nnpfc_num_kmac_operations_idc in nnpfcBase is greater than 0), then nnpfc_num_kmac_operations_idc in nnpfcCurr must be greater than 0 and less than or equal to nnpfc_num_kmac_operations_idc in nnpfcBase.

[0143] (7) If nnpfc_total_kilobyte_size in nnpfcBase is equal to 0, then nnpfc_total_kilobyte_size in nnpfcCurr must also be equal to 0.

[0144] (8) Otherwise (where nnpfc_total_kilobyte_size in nnpfcBase is greater than 0), nnpfc_total_kilobyte_size in nnpfcCurr must be greater than 0 or less than or equal to nnpfc_total_kilobyte_size in nnpfcBase.

[0145] nnpfc_out_sub_c_flag can indicate the values ​​of the variables outSubWidthC and outSubHeightC if nnpfc_purpose & 0x02 is not equal to 0. A value of 1 for nnpfc_out_sub_c_flag indicates that the value of outSubWidthC is 1 and the value of outSubHeightC is 1. A value of 0 for nnpfc_out_sub_c_flag indicates that the value of outSubWidthC is 2 and the value of outSubHeightC is 1. If the value of ChromaFormatIdc is 2 and nnpfc_out_sub_c_flag exists, the value of nnpfc_out_sub_c_flag must be the same as 1.

[0146] nnpfc_out_colour_format_idc can indicate the NNPFC output color format and the resulting values ​​of the variables outSubWidthC and outSubHeightC, provided that nnpfc_purpose & 0x20 is not equal to 0. A value of 1 for nnpfc_out_colour_format_idc indicates that the NNPFC output color format is 4:2:0, and both outSubWidthC and outSubHeightC are equal to 2. A value of 2 for nnpfc_out_colour_format_idc indicates that the NNPFC output color format is 4:2:2, with outSubWidthC being 2 and outSubHeightC being 1. A value of 3 for nnpfc_out_colour_format_idc indicates that the NNPFC output color format is 4:2:4, and both outSubWidthC and outSubHeightC are 1. The value of nnpfc_out_colour_format_idc may be restricted to not be equal to 0.

[0147] If both nnpfc_purpose & 0x02 and nnpfc_purpose & 0x20 are the same as 0, then outSubWidthC and outSubHeightC can be inferred to be the same as SubWidthC and SubHeightC, respectively.

[0148] nnpfc_pic_width_in_luma_samples and nnpfc_pic_height_in_luma_samples can indicate the width and height of the luma sample array of the picture, respectively, resulting from applying the NNPF identified by nnpfc_id to the cropped, decoded output picture. If nnpfc_pic_width_in_luma_samples and nnpfc_pic_height_in_luma_samples are not present, they may be inferred to be the same as CroppedWidth and CroppedHeight, respectively. The value of nnpfc_pic_width_in_luma_samples should be in the range of CroppedWidth to CroppedWidth*16-1. The value of nnpfc_pic_height_in_luma_samples should be in the range of CroppedHeight to CroppedHeight*16-1.

[0149] nnpfc_num_input_pics_minus1+1 can indicate the number of decoded output pictures used as input to NNPF. The value of nnpfc_num_input_pics_minus1 may be restricted to be within the range of 0 to 63.

[0150] nnpfc_interpolated_pics[i] can indicate the number of interpolated pictures generated by NNPF between the i-th picture and the (i+1)-th picture used as input to NNPF. The value of nnpfc_interpolated_pics[i] may be restricted to the range of 0 to 63. The value of nnpfc_interpolated_pics[i] may be restricted to being greater than 0 for at least one i in the range of 0 to nnpfc_num_input_pics_minus1-1.

[0151] A value of 1 for nnpfc_input_pic_output_flag[i] indicates that NNPF will generate a corresponding output picture for the i-th input picture. A value of 0 for nnpfc_input_pic_output_flag[i] indicates that NNPF will not generate a corresponding output picture for the i-th input picture.

[0152] The variables `numInputPics`, which indicates the number of pictures used as input to NNPF, and `numOutputPics`, which indicates the total number of pictures generated as a result of NNPF, may be derived as shown in Table 5.

[0153] [Table 5]

[0154] A value of 1 for nnpfc_component_last_flag indicates that the last dimension of the input tensor for NNPF and the output tensor, outputTensor (the result of NNPF), are currently used for the channel. A value of 0 for nnpfc_component_last_flag indicates that the third dimension of the input tensor for NNPF and the output tensor, outputTensor (the result of NNPF), are currently used for the channel.

[0155] The first dimension of the input and output tensors may be used as a batch index, as used in some neural network frameworks. The formula within the semantics of this SEI message uses a batch size corresponding to a batch index such as 0, but the batch size used as input for neural network inference may be determined by the implementation of post-processing.

[0156] For example, when the value of nnpfc_inp_order_idc is the same as 3 and the value of nnpfc_auxiliary_inp_idc is the same as 1, the input tensor may have 7 channels, including 4 lumer matrices, 2 chroma matrices, and 1 auxiliary input matrix. In this case, the DeriveInputTensors() process can induce each of the 7 channels of the input tensor one by one, and when a particular channel is processed among these channels, that channel may be called the current channel during the process.

[0157] nnpfc_inp_format_idc can indicate how to convert the sample values ​​of the cropped decoded output picture into NNPF input values. If nnpfc_inp_format_idc is 0, the input values ​​for NNPF are real numbers, and the InpY() and InpC() functions may be specified as shown in Equation 1.

[0158]

number

[0159] If the value of nnpfc_inp_format_idc is 1, then the input values ​​for NNPF are unsigned integer numbers, and the InpY() and InpC() functions may be induced as shown in Table 6.

[0160] [Table 6]

[0161] The variable inpTensorBitDepth Y may be derived from the syntax element nnpfc_inp_tensor_luma_bitdepth_minus8 described below. inpTensorBitDepth C may be derived from the syntax element nnpfc_inp_tensor_chroma_bitdepth_minus8 described below.

[0162] Values of nnpfc_inp_format_idc greater than 1 may be reserved for future use and may not be present in the bitstream. The decoder must ignore NNPFC SEI messages containing reserved values of nnpfc_inp_format_idc.

[0163] nnpfc_inp_tensor_luma_bitlength_minus8 + 8 can indicate the bit depth of luma sample values in the input integer tensor. inpTensorBitDepth Y The value of

[0164]

Number

[0165] The value of nnpfc_inp_tensor_luma_bitlength_minus8 may be restricted to be in the range of 0 to 24.

[0166] nnpfc_inp_tensor_chroma_bitdepth_minus8 + 8 can indicate the bit depth of chroma sample values in the input integer tensor. inpTensorBitDepth C The value of

[0167]

Number

[0168] The value of nnpfc_inp_tensor_chroma_bitdepth_minus8 may be restricted to a range of 0 to 24.

[0169] nnpfc_inp_order_idc can specify how the sample array of the cropped, decoded output picture is aligned to one of the input pictures for NNPF.

[0170] The value of nnpfc_inp_order_idc must be in the range of 0 to 3 in the bitstream. Values ​​of nnpfc_inp_order_idc between 4 and 255 do not exist in the bitstream. The decoder must ignore NNPFC SEI messages with nnpfc_inp_order_idc in the range of 4 to 255. Values ​​of nnpfc_inp_order_idc greater than 255 do not exist in the bitstream and are not reserved for future use.

[0171] If the value of ChromaFormatIdc is not 1, then the value of nnpfc_inp_order_idc must not be 3.

[0172] Table 7 contains explanations regarding the nnpfc_inp_order_idc value.

[0173] [Table 7]

[0174] A patch may be a rectangular array of samples from the picture components (e.g., lumens or chroma components).

[0175] A value of nnpfc_auxiliary_inp_idc greater than 0 indicates that auxiliary input data exists in the NNPF input tensor. A value of nnpfc_auxiliary_inp_idc of 0 indicates that auxiliary input data does not exist in the input tensor. A value of nnpfc_auxiliary_inp_idc of 1 indicates that auxiliary input data is induced by the methods disclosed in Tables 8 to 10.

[0176] The value of nnpfc_auxiliary_inp_idc must be in the range of 0 to 1 in the bitstream. Values ​​of nnpfc_inp_order_idc between 2 and 255 do not exist in the bitstream. The decoder must ignore NNPFC SEI messages with nnpfc_inp_order_idc in the range of 2 to 255. Values ​​of nnpfc_inp_order_idc greater than 255 do not exist in the bitstream and are not reserved for future use.

[0177] If the value of nnpfc_auxiliary_inp_idc is the same as 1, the variable strengthControlScaledVal may be derived as shown in equation 4.

[0178]

number

[0179] The process DeriveInputTensors() for deriving the input tensor inputTensor for given vertical sample coordinates cTop and horizontal sample coordinates cLeft specifying the upper-left sample position of the sample patch included in the input tensor can be shown as the join in Tables 8-10.

[0180] [Table 8]

[0181] [Table 9]

[0182] [Table 10]

[0183] A value of 1 for nnpfc_separate_colour_description_present_flag indicates that the unique combination of color primaries, transformation properties, and matrix coefficients for the picture, as determined by NNPF, is specified in the SEI message syntax structure. A value of 0 for nnfpc_separate_colour_description_present_flag indicates that the combination of color primaries, transformation properties, and matrix coefficients for the picture, as determined by NNPF, is identical to that displayed in the CLVS VUI parameters.

[0184] nnpfc_colour_primaries may have the same semantics as defined for the vui_colour_primaries syntax element, except as follows:

[0185] - nnpfc_colour_primaries can indicate the primary colors of a picture that appear as a result of applying the NNPF specified in the SEI message, rather than the primary colors used in CLVS.

[0186] - If nnpfc_colour_primaries is not present in the NNPFC SEI message, the value of nnpfc_colour_primaries may be inferred to be the same as the value of vui_colour_primaries.

[0187] nnpfc_transfer_characteristics may have the same semantics as defined for the vui_transfer_characteristics syntax element, except as follows:

[0188] - nnpfc_transfer_characteristics can indicate the transformation characteristics of the picture that appear as a result of applying the NNPF specified in the SEI message, rather than the transformation characteristics used in CLVS.

[0189] - If nnpfc_transfer_characteristics is not present in the NNPFC SEI message, the value of nnpfc_transfer_characteristics may be inferred to be the same as the value of vui_transfer_characteristics.

[0190] nnpfc_matrix_coeffs may have the same semantics as specified for the vui_matrix_coeffs syntax element, except as follows:

[0191] - nnpfc_matrix_coeffs can indicate the matrix coefficients of the picture that appear as a result of applying the NNPF specified in the SEI message, rather than the matrix coefficients used in CLVS.

[0192] - If nnpfc_matrix_coeffs is not present in the NNPFC SEI message, the value of nnpfc_matrix_coeffs can be inferred to be the same as the value of vui_matrix_coeffs.

[0193] - The acceptable values ​​for nnpfc_matrix_coeffs do not need to be restricted by the chroma format of the decoded video picture, as shown by the ChromaFormatIdc value for the semantics of the VUI parameter.

[0194] - If the value of nnpfc_matrix_coeffs is the same as 0, the value of nnpfc_out_order_idc must not be the same as 1 or 3.

[0195] The value 0 of nnpfc_out_format_idc can indicate that for the bit depth bitDepth required for subsequent post - processing or display, the sample values output by the NNPF are real numbers that are linearly mapped from the range of values from 0 to 1 to the range of unsigned integer values from 0 to (1 << bitDepth)-1. The value 1 of nnpfc_out_format_idc can indicate that the luma sample values output by the NNPF are unsigned integers in the range of 0 to (1 << (nnpfc_out_tensor_luma_bitlength_minus8 + 8))-1, and the chroma sample values output by the NNPF can be indicated as unsigned integers in the range of 0 to (1 << (nnpfc_out_tensor_chroma_bitlength_minus8 + 8))-1.

[0196] Values of nnpfc_out_format_idc greater than 1 may be reserved for future use and do not exist in the bitstream. The decoder must ignore NNPFC SEI messages containing reserved values of nnpfc_out_format_idc.

[0197] nnpfc_out_tensor_luma_bitdepth_minus8 + 8 can indicate the bit depth of the luma sample values in the output integer tensor. The value of nnpfc_out_tensor_luma_bitdepth_minus8 must exist in the range of 0 to 24.

[0198] nnpfc_out_tensor_chroma_bitdepth_minus8 + 8 can indicate the bit depth of the chroma sample values in the output integer tensor. The value of nnpfc_out_tensor_chroma_bitdepth_minus8 must exist in the range of 0 to 24.

[0199] If nnpfc_purpose & 0x10 is not equal to 0, then the value of nnpfc_out_format_idc must be equal to 1, and at least one of the following restrictions may be true.

[0200] - nnpfc_out_tensor_luma_bitdepth_minus8+8 is BitDepth Y bigger

[0201] - nnpfc_out_tensor_chroma_bitdepth_minus8+8 is BitDepth C bigger

[0202] nnpfc_out_order_idc can indicate the output order of samples output from NNPF. The value of nnpfc_out_order_idc must be in the range of 0 to 3 in the bitstream. Values ​​of nnpfc_out_order_idc from 4 to 255 do not exist in the bitstream. The decoder must ignore NNPFC SEI messages with nnpfc_out_order_idc in the range of 4 to 255. Values ​​of nnpfc_out_order_idc greater than 255 do not exist in the bitstream and are not reserved for future use. If the value of nnpfc_purpose & 0x02 is 0, the value of nnpfc_out_order_idc must not be identical to 3.

[0203] Table 11 provides explanations for the values ​​of nnpfc_out_order_idc.

[0204] [Table 11]

[0205] The StoreOutputTensors() process for deriving sample values ​​in the output sample arrays FilteredYPic, FilteredCbPic, and FilteredCrPic, filtered from the output tensor outputTensor, which is based on the given vertical sample coordinate cTop and the horizontal sample coordinate cLeft indicating the upper-left sample position for the patch of samples contained in the input tensor, may be expressed as the joins in Tables 12 and 13.

[0206] [Table 12]

[0207] [Table 13]

[0208] nnpfc_overlap can indicate the number of horizontal and vertical overlapping samples of adjacent input tensors in NNPF. The value of nnpfc_overlap must be within the range of 0 to 16383.

[0209] A value of 1 for nnpfc_constant_patch_size_flag indicates that NNPF accepts the exact patch size specified by nnpfc_patch_width_minus1 and nnpfc_patch_height_minus1 as input. A value of 0 for nnpfc_constant_patch_size_flag indicates that NNPF accepts any patch size with width inpPatchWidth and height inpPatchHeight as input. Here, the width of the extended patch (i.e., the patch plus the overlapping area) is the same as inpPatchWidth+2*nnpfc_overlap, and the height of the extended patch is the same as inpPatchHeight+2*nnpfc_overlap, and the height of the extended patch is the same as nnpfc_extended_patch_height_cd_delta_minus1+1+2*nnpfc_overlap, and the height of the extended patch is the same as inpPatchHeight+2*nnpfc_overlap, and the height of the extended patch is the same as nnpfc_extended_patch_height_cd_delta_minus1+1+2*nnpfc_overlap.

[0210] npfc_patch_width_minus1+1 can indicate the number of horizontal samples required for the patch size input to NNPF when the value of nnpfc_constant_patch_size_flag is 1. The value of nnpfc_patch_width_minus1 must be in the range of 0 to Min(32766,CroppedWidth-1).

[0211] npfc_patch_height_minus1+1 can indicate the number of vertical samples required for the patch size input to NNPF when the value of nnpfc_constant_patch_size_flag is 1. The value of nnpfc_patch_height_minus1 must be in the range of 0 to Min(32766,CroppedHeight-1).

[0212] nnpfc_extended_patch_width_cd_delta_minus1+1+2*nnpfc_overlap can represent the common divisor of the allowed values ​​for the extended patch width required when inputting into NNPF when the value of nnpfc_constant_patch_size_flag is 0. The value of nnpfc_extended_patch_width_cd_delta_minus1 must be in the range of 0 to Min(32766,CroppedWidth-1).

[0213] nnpfc_extended_patch_height_cd_delta_minus1+1+2*nnpfc_overlap can represent the common divisor of the allowed values ​​for the extended patch height required when inputting into NNPF when the value of nnpfc_constant_patch_size_flag is 0. The value of nnpfc_extended_patch_height_cd_delta_minus1 must be in the range of 0 to Min(32766,CroppedHeight-1).

[0214] The variables inpPatchWidth and inpPatchHeight may be set to the patch size width and patch size height, respectively.

[0215] If the value of nnpfc_constant_patch_size_flag is 0, the following may be applied.

[0216] - The values ​​of inpPatchWidth and inpPatchHeight may be provided by an external means or set by the post-processor itself.

[0217] - The value of inpPatchWidth + 2 * nnpfc_overlap must be a positive integer multiple of nnpfc_extended_patch_width_cd_delta_minus1 + 1 + 2 * nnpfc_overlap, and inpPatchWidth must be less than or equal to CroppedWidth. The value of inpPatchHeight + 2 * nnpfc_overlap must be a positive integer multiple of nnpfc_extended_patch_height_cd_delta_minus1 + 1 + 2 * nnpfc_overlap, and inpPatchHeight must be less than or equal to CroppedHeight.

[0218] Otherwise, (if the value of nnpfc_constant_patch_size_flag is 1), the value of inpPatchWidth may be set to the same as nnpfc_patch_width_minus1+1, and the value of inpPatchHeight may be set to the same as nnpfc_patch_height_minus1+1.

[0219] The variables outPatchWidth, outPatchHeight, horCScaling, verCScaling, outPatchCWidth, and outPatchCHeight may be derived as shown in Table 14.

[0220] [Table 14]

[0221] The requirement for bitstream conformance is that outPatchWidth*CroppedWidth must be the same as nnpfc_pic_width_in_luma_samples*inpPatchWidth, and outPatchHeight*CroppedHeight must be the same as nnpfc_pic_height_in_luma_samples*inpPatchHeight.

[0222] nnpfc_padding_type can indicate the padding process when referencing sample locations outside the boundaries of the cropped decoded output picture, as described in Table 15. The value of nnpfc_padding_type must be in the range of 0 to 15.

[0223] [Table 15]

[0224] nnpfc_luma_padding_val can indicate the luma value to be used for padding when the value of nnpfc_padding_type is 4.

[0225] nnpfc_cb_padding_val can indicate the Cb value to be used for padding when the value of nnpfc_padding_type is 4.

[0226] nnpfc_cr_padding_val can indicate the Cr value to be used for padding when the value of nnpfc_padding_type is 4.

[0227] The InpSampleVal(y,x,picHeight,picWidth,CroppedPic) function, whose inputs are the vertical sample position y, the horizontal sample position x, the picture height picHeight, the picture width picWidth, and the sample array CroppedPic, can return the derived SampleVal value as shown in Table 16.

[0228] For inputs to the InpSampleVal() function, vertical positions may be placed before horizontal positions for compatibility with the input tensor rules of some inference engines.

[0229] [Table 16]

[0230] The processes in Table 17 may be used to perform patch filtering using NNPF PostProcessingFilter() to generate filtered and / or interpolated pictures, which may include a Y sample array FilteredYPic, a Cb sample array FilteredCbPic, and a Cr sample array FilteredCrPic, as shown by nnpfc_out_order_idc.

[0231] [Table 17]

[0232] The order of the pictures in the saved output tensor may be the output order, and the output order generated by applying NNPF to the output order may be analyzed as an output order that does not conflict with the output order of the input pictures.

[0233] A value of 1 for nnpfc_complexity_info_present_flag indicates that there is one or more syntax elements that indicate the complexity of NNPF associated with nnpfc_id. A value of 0 for nnpfc_complexity_info_present_flag indicates that there are no syntax elements that indicate the complexity of NNPF associated with nnpfc_id.

[0234] A value of 0 for nnpfc_parameter_type_idc can indicate that the neural network uses only integer parameters. A value of 1 for nnpfc_parameter_type_flag can indicate that the neural network can use floating-point or integer parameters. A value of 2 for nnpfc_parameter_type_idc can indicate that the neural network uses only binary parameters. A value of 3 for nnpfc_parameter_type_idc may be reserved for future use and is not present in the bitstream. The decoder must ignore NNPFC SEI messages where the value of nnpfc_parameter_type_idc is 3.

[0235] The values ​​0, 1, 2, and 3 for nnpfc_log2_parameter_bit_length_minus3 indicate that the neural network will not use parameters with bit lengths greater than 8, 16, 32, and 64, respectively. If nnpfc_parameter_type_idc exists and nnpfc_log2_parameter_bit_length_minus3 does not exist, the neural network does not need to use parameters with bit lengths greater than 1.

[0236] nnpfc_num_parameters_idc can indicate the maximum number of neural network parameters for NNPF in units of 2048. A value of 0 for nnpfc_num_parameters_idc indicates that the maximum number of neural network parameters is unknown. The value of nnpfc_num_parameters_idc must be in the range of 0 to 52. Values ​​of nnpfc_num_parameters_idc greater than 52 do not exist in the bitstream. The decoder must ignore NNPFC SEI messages with nnpfc_num_parameters_idc greater than 52.

[0237] If the value of nnpfc_num_parameters_idc is greater than 0, the maxNumParameters variable may be derived as shown in equation 5.

[0238]

number

[0239] The number of neural network parameters in NNPF may be limited to a number less than or equal to maxNumParameters.

[0240] A value of nnpfc_num_kmac_operations_idc greater than 0 can indicate that the maximum number of multiply-accumulate operations per sample in NNPF is less than or equal to nnpfc_num_kmac_operations_idc * 1000. A value of nnpfc_num_kmac_operations_idc of 0 can indicate that the maximum number of multiply-accumulate operations in the network is unknown. The value of nnpfc_num_kmac_operations_idc is between 0 and 2. 32 It must exist within the range of -2.

[0241] A value of nnpfc_total_kilobyte_size greater than 0 can indicate the total size (in kilobytes) required to store the uncompressed parameters of the neural network. The total size in bits may be greater than or equal to the sum of the bits used to store each parameter. nnpfc_total_kilobyte_size may be the total size (in bits) divided by 8000 and rounded. A value of nnpfc_total_kilobyte_size of 0 can indicate that the total size required to store the parameters for the neural network is unknown. The value of nnpfc_total_kilobyte_size is between 0 and 2. 32 It must exist within the range of -2.

[0242] nnpfc_reserved_zero_bit_b must be equivalent to 0 in the bitstream. The decoder must ignore NNPFC SEI messages where nnpfc_reserved_zero_bit_b is not 0.

[0243] nnpfc_payload_byte[i] may contain the i-th byte of the bitstream. The byte sequence nnpfc_payload_byte[i] for all existing values ​​of i must be a complete bitstream compliant with ISO / IEC 15938-17.

[0244] Neural network post-filter activation (NNFPA)

[0245] Table 18 shows the syntax structure for NNFPA.

[0246] [Table 18]

[0247] The NNPFA syntax structure shown in Table 18 may be signaled in the form of an SEI message. An SEI message that signals the NNPFA syntax structure shown in Table 18 can be called an NNPFA SEI message.

[0248] An NNPFA SEI message can activate or deactivate the possible use of a target neural network post-processing filter (NNPF) identified by nnpfa_target_id for post-processing filtering of a picture set. For a particular picture in which an NNPF has been activated, the target NNPF may be the NNPF identified by the last NNPFC SEI message having the same nnpfc_id as nnpfa_target_id. Here, the last NNPFC SEI message may precede the first VCL NAL unit of the current picture in the decoding order and may not be an iteration of an NNPFC SEI message containing the base NNPF.

[0249] Multiple NNPFA SEI messages may exist for the same picture if the NNPF is used for another purpose or filters another color component.

[0250] The nnpfa_target_id can indicate the NNPF specified by one or more NNPFC SEI messages that have the same nnpfc_id as the nnfpa_target_id in relation to the current picture.

[0251] The value of nnpfa_target_id must be in the range of 0 to 2 32 -2. Values in the range of 256 to 511 and 2 31 ~2 32 Values of nnpfa_target_id within the range of -2 may be reserved for future use. The decoder must ignore NNPFA SEI messages that have nnpfa_target_id within the range of 256 to 511 or 2 31 ~2 32 -2.

[0252] An NNPFA SEI message with a specific value of nnpfa_target_id must not be present in the current PU unless one or both of the following conditions are true.

[0253] - There is an NNPFC SEI message in the current CLVS that has the same nnpfc_id as the specific value of nnpfa_target_id that exists in a PU before the current PU in decoding order

[0254] - There is an NNPFC SEI message that has the same nnpfc_id as the specific value of nnpfa_target_id of the current PU

[0255] If a PU contains all NNPFC SEI messages with a specific value for nnpfc_id and all NNPFA SEI messages with the same nnpfa_target_id as the specific value for nnpfc_id, then the NNPFC SEI messages must precede the NNPFA SEI messages in the decoding order.

[0256] A value of 1 for nnpfa_cancel_flag can indicate that the persistence of the target NNPF, which was set by any previous NNPFA SEI message having the same nnpfa_target_id as the current SEI message, is cancelled. That is, the target NNPF will not be used any further unless it is activated by another NNPFA SEI message having the same nnpfa_target_id as the current SEI message and the same nnpfa_cancel_flag of 0. A value of 0 for nnpfa_cancel_flag can indicate that nnpfa_persistence_flag will continue.

[0257] The nnpfa_persistence_flag can indicate the persistence of the target NNPF for the current layer. A value of nnpfa_persistence_flag of 0 indicates that the target NNPF may only be used for post-processing filtering on the current picture. A value of nnpfa_persistence_flag of 1 indicates that the target NNPF may be used for post-processing filtering on the current picture and all subsequent pictures in the current layer in output order until one or more of the following conditions are true:

[0258] - A new CLVS for the current layer is started.

[0259] - Bitstream ends

[0260] - The picture in the current layer associated with the NNPFA SEI message that has the same nnpfa_target_id as the current SEI message and the same nnpfa_cancel_flag as 1 will be output after the current picture in the output order.

[0261] The target NNPF does not apply to subsequent pictures in the current layer associated with an NNPFA SEI message that has the same nnpfa_target_id and nnpfa_cancel_flag as the current SEI message.

[0262] nnpfcTargetPictures may be the set of pictures associated with the last NNPFC SEI message that currently precedes the NNPFA SEI message in the decoding order and has the same nnpfc_id as nnpfa_target_id. nnpfaTargetPictures may be the set of pictures whose target NNPF is currently activated by the NNPFA SEI message. All arbitrary pictures included in nnpfaTargetPictures should also be included in nnpfcTargetPictures.

[0263] Post-filter hint

[0264] Table 19 shows the syntax structure for post-filter hints.

[0265] [Table 19]

[0266] The post-filter hint syntax structures in Table 19 may be signaled in the form of SEI messages. SEI messages that signal the post-filter hint syntax structures in Table 19 can be called post-filter hint SEI messages.

[0267] The post-filter hint SEI message can provide post-filter coefficients or correlation information for the design of the post-filter so that the decoded and output picture set can be potentially used for post-processing to obtain improved display quality.

[0268] A value of 1 for the filter_hint_cancel_flag can indicate that the SEI message cancels the persistence of previous post-filter hint SEI messages in the output order to which the SEI message is applied to the current layer. A value of 0 for the filter_hint_cancel_flag can indicate that the post-filter hint information continues.

[0269] The filter_hint_persistence_flag can indicate the persistence of the post-filter hint SEI message for the current layer. A value of 0 for the filter_hint_persistence_flag can indicate that the post-filter hint is applied only to the currently decoded picture. A value of 1 for the filter_hint_persistence_flag can indicate that the post-filter hint SEI message is applied to the currently decoded picture and persists for all subsequent pictures in the current layer in the output order until one or more of the following conditions are true.

[0270] - A new CLVS of the current layer is started

[0271] - The bitstream ends

[0272] - The pictures in the current layer of the AU associated with the post-filter hint SEI message are output next to the current picture in the output order.

[0273] The filter_hint_size_y can indicate the vertical size of the filter coefficient or correlation array. The value of the filter_hint_size_y must be in the range of 1 to 15.

[0274] `filter_hint_size_x` can represent the filter coefficient or the horizontal size of the correlation array. The value of `filter_hint_size_x` must be in the range of 1 to 15.

[0275] `filter_hint_type` can indicate the type of filter hint transmitted, as shown in Table 20. The value of `filter_hint_type` must be in the range of 0 to 2. A `filter_hint_type` value equal to 3 does not exist in the bitstream. The decoder must ignore post-filter hint SEI messages where `filter_hint_type` is 3.

[0276] [Table 20]

[0277] A value of 1 for filter_hint_chroma_coeff_present_flag indicates that a filter coefficient exists for the chroma. A value of 0 for filter_hint_chroma_coeff_present_flag indicates that no filter coefficient exists for the chroma.

[0278] `filter_hint_value[cIdx][cy][cx]` can represent the filter coefficients, or the cross-correlation matrix elements between the original signal and the decoded signal, with 16-bit precision. The value of `filter_hint_value[cIdx][cy][cx]` is -2 31 +1~2 31 It must be within the range of -1. cIdx may indicate the associated color element, cy may indicate the vertical counter, and cx may indicate the horizontal counter. Depending on the value of filter_hint_type, the following may be applied:

[0279] - If the value of filter_hint_type is 0, the coefficients of a 2D FIR (Finite Impulse Response) filter of size filter_hint_size_y * filter_hint_size_x may be transmitted.

[0280] - On the other hand, if the value of filter_hint_type is 1, the filter coefficients of two one-dimensional FIR filters may be transmitted. In this case, the value of filter_hint_size_y must be 2. An index cy of 0 can indicate the filter coefficient of a horizontal filter, and a cy of 1 can indicate the filter coefficient of a vertical filter. In the filtering process, the horizontal filter may be applied first, and the result may be filtered by the vertical filter.

[0281] - Otherwise (if the value of filter_hint_type is 2), the transmitted hint can represent the cross-correlation matrix between the original signal s and the decoded signal s'.

[0282] A normalized cross-correlation matrix for related color components identified by cIdx of size filter_hint_size_y*filter_hint_size_x may be defined as shown in Equation 6.

[0283]

number

[0284] In Equation 6, s represents the sample array of the color component cIdx of the original picture, s’ represents the array of the decoded picture corresponding thereto, h represents the vertical height of the relevant color component, w represents the horizontal width of the relevant color component, and bitDepth represents the bit depth of the color component. Also, OffsetY is the same as (filter_hint_size_y>>1), OffsetX is the same as (filter_hint_size_x>>1), the range of cy is 0<=cy<filter_hint_size_y, and the range of cx is 0<=cx<filter_hint_size_x.

[0285] The decoder can derive a Wiener post-filter from the cross-correlation matrix of the original signal and the decoded signal and the auto-cross-correlation matrix of the decoded signal.

[0286] Problems with conventional technology

[0287] The problems of the prior art according to the present disclosure are as follows.

[0288] The conventional NNPFC (neural-network post-filter characteristics) SEI message does not consider anything in relation to discardable picture(s) and non-output picture(s). Without any description thereof, the following situations may be possible or permitted.

[0289] Situation 1) The NNPFC SEI message may be included in an access unit (AU) including a picture displayed as a discardable picture.

[0290] Situation 2) An AU containing a picture displayed as a discardable picture or a non-output picture may contain an NNPFA (neural-network post-filter activation) SEI message.

[0291] Situation 3) When the NNPF is activated, the NNPF may take an input picture that includes one or more discardable pictures and / or non-output pictures.

[0292] However, NNPFC SEI messages and / or NNPFA SEI messages can cause serious problems when transmitted in an AU containing a discardable picture. Specifically, if a picture contained in an AU is discarded, the SEI message transmitted in that AU may also be discarded. Furthermore, NNPFA SEI messages should not be transmitted in an AU containing a non-output picture because when an NNPF is activated by an NNPFA SEI message, it breaks the design of the SEI message where the current picture (i.e., the picture contained in the same AU as the NNPFA SEI message) becomes the first input picture to the NNPF. In addition, if one or more input pictures to the NNPF are discardable pictures and / or non-output pictures, the list of input pictures in the encoder and the list of input pictures in the decoder may not match.

[0293] To address the aforementioned problems with the conventional technology, improvements are needed to the NNPFC SEI message and / or NNPFA SEI message.

[0294] Examples

[0295] Hereinafter, NNPFC has the NNPFC syntax structure shown in Tables 1 to 3 and may be signaled in the form of an SEI message; in this case, NNPFC may be an NNPFC SEI message. NNPFA has the NNPFA syntax structure shown in Table 18 and may be signaled in the form of an SEI message; in this case, NNPFA may be an NNPFA SEI message. Post-filter hints have the post-filter hint syntax structure shown in Table 19 and may be signaled in the form of an SEI message; in this case, post-filter hints may be post-filter hint SEI messages.

[0296] The embodiments relating to this disclosure may include various configurations for improving some or all of the problems described above. Each configuration may be applied individually or in combination of two or more.

[0297] Configuration 1) Restrictions can be explicitly stated to prevent NNPFC SEI messages from existing within an AU containing discardable pictures. A discardable picture can mean a picture that does not affect the decoding of other pictures in the encoded bitstream and may be removed from the bitstream.

[0298] Configuration 2) As an alternative, restrictions can be explicitly stated to prevent NNPFC SEI messages from being associated with discardable pictures.

[0299] Configuration 3) Restrictions can be explicitly stated to prevent the presence of NNPFA SEI messages within an AU containing a non-output picture. A non-output picture can mean an encoded picture that can be decoded by a decoder, but from which the decoder does not need to generate a reconstructed picture.

[0300] Configuration 4) As an alternative, restrictions can be explicitly stated to prevent NNPFA SEI messages from being associated with non-output pictures.

[0301] Configuration 5) A restriction can be explicitly stated that the input picture to the activated NNPF must not be a discardable picture.

[0302] Refer to Tables 1 to 3 and Table 18 to see the above-mentioned NNPFC syntax structure and semantics, and NNPFA syntax structure and semantics.

[0303] According to this disclosure, by considering at least a part of the above-mentioned configurations 1 to 5 and improving at least a part of the above-mentioned NNPFC syntax structure and semantics, and NNPFA syntax structure and semantics, at least a part of the above-mentioned problems can be solved.

[0304] In this disclosure, AU is used as the unit that includes NNPF SEI messages (NNPFC SEI messages and / or NNPFA SEI messages) and pictures. However, it will be obvious to those skilled in the art that the unit that includes NNPF SEI messages and pictures is not limited to AU, and any unit such as PU (picture unit) may be used. Furthermore, such units may be collectively referred to as "unit information" in this disclosure.

[0305] Example 1

[0306] Embodiment 1 of this disclosure is related to the above-mentioned configurations 1, 3, and / or 5. According to Embodiment 1 of this disclosure, the above-mentioned problems of the prior art can be resolved by restricting NNPFC SEI messages and / or NNPFA SEI messages from being included in unit information that contains discardable pictures and / or non-output pictures.

[0307] Embodiment 1 of this disclosure can restrict, modify, and / or alter the semantics of NNPFC SEI messages.

[0308] Specifically, NNPFC SEI messages may be restricted so that they do not exist in an AU containing a discardable encoded picture (discardable picture). As described above, a discardable picture can mean a picture that does not affect the decoding of other pictures in the encoded bitstream and may be removed / discarded from the bitstream.

[0309] Furthermore, when the NNPF defined by the NNPFC SEI message is activated by the NNPFA SEI message, the list of input pictures for the NNPF may be restricted so as not to include discardable pictures.

[0310] The limitations on the NNPFC SEI message in Embodiment 1 of this disclosure may be embodied by explicitly stating the limitations in the semantics of the NNPFC SEI message.

[0311] More specifically, the semantics of NNPFC SEI messages may explicitly include the limitations listed in Table 21 below.

[0312] [Table 21]

[0313] Furthermore, Embodiment 1 of this disclosure may restrict, modify, and / or alter the semantics of NNPFA SEI messages. Specifically, it may restrict NNPFA SEI messages from being present in AUs that contain encoded pictures that are not output pictures (non-output pictures).

[0314] For example, if an AU contains an NNPFA SEI message, the picture included in that AU may be restricted to always be output. In this case, AU may be replaced with the term unit information, as described above. The restriction to ensure that the picture is output may be implemented by restricting the value of the information (e.g., a flag) indicating whether the picture is output to a value indicating "output".

[0315] The limitations on the NNPFA SEI message in Embodiment 1 of this disclosure may be embodied by explicitly stating the limitations in the semantics of the NNPFA SEI message.

[0316] More specifically, the semantics of the NNPFA SEI message may explicitly include the limitations listed in Table 22 below.

[0317] [Table 22]

[0318] According to Embodiment 1 of this disclosure, it is expected that when a discardable picture is discarded, the NNPFC SEI messages included in the same AU will also be discarded. Furthermore, it is expected that a picture activated by an NNPFA SEI message will not be output. In addition, it is expected that a mismatch will occur between the list of input pictures in the encoder and the list of input pictures in the decoder. Including these effects, Embodiment 1 of this disclosure is expected to resolve the problems of the prior art described above.

[0319] Example 2

[0320] Embodiment 2 of this disclosure relates to configurations 2, 4, and / or 5. According to Embodiment 2 of this disclosure, the problems of the prior art described above can be resolved by restricting NNPFC SEI messages and / or NNPFA SEI messages from being associated with discardable pictures and / or non-output pictures.

[0321] Embodiment 2 of this disclosure can restrict, modify, and / or alter the semantics of NNPFC SEI messages.

[0322] Specifically, NNPFC SEI messages may be restricted from being associated with discardable encoded pictures (discardable pictures). As mentioned above, a discardable picture can mean a picture that does not affect the decoding of other pictures in the encoded bitstream and may be removed / discarded from the bitstream.

[0323] Furthermore, when the NNPF defined by the NNPFC SEI message is activated by the NNPFA SEI message, the list of input pictures for the NNPF may be restricted so as not to include discardable pictures.

[0324] The limitations on the NNPFC SEI message in Embodiment 2 of this disclosure may be embodied by explicitly stating the limitations in the semantics of the NNPFC SEI message.

[0325] More specifically, the semantics of NNPFC SEI messages may explicitly include the limitations listed in Table 23 below.

[0326] [Table 23]

[0327] Furthermore, Embodiment 2 of this disclosure may restrict, modify, and / or alter the semantics of the NNPFA SEI message. Specifically, the NNPFA SEI message may be restricted so as not to be associated with an encoded picture that is not an output picture (non-output picture).

[0328] The limitations on the NNPFA SEI message in Embodiment 2 of this disclosure may be embodied by explicitly stating the limitations in the semantics of the NNPFA SEI message.

[0329] More specifically, the semantics of the NNPFA SEI message may explicitly include the limitations listed in Table 24 below.

[0330] [Table 24]

[0331] According to Embodiment 2 of this disclosure, it is expected that when a discardable picture is discarded, the NNPFC SEI messages included in the same AU will also be discarded. Furthermore, it is expected that a picture activated by an NNPFA SEI message will not be output. In addition, it is expected that a mismatch will occur between the list of input pictures in the encoder and the list of input pictures in the decoder. Including these effects, Embodiment 2 of this disclosure is expected to resolve the problems of the prior art described above.

[0332] The following describes video encoding and video decoding methods according to various embodiments of the present invention.

[0333] Figure 5 is a flowchart illustrating a video encoding method to which the embodiments of this disclosure can be applied.

[0334] Figure 6 is a flowchart illustrating a video decoding method to which the embodiments of this disclosure can be applied.

[0335] The video encoding method shown in Figure 5 may be performed by the video encoding device 100, and the video decoding method shown in Figure 6 may be performed by the video decoding device 200.

[0336] Referring to Figure 5, the video encoding device can generate NNPF (Neural-network post-filter) related information regarding the neural network post-processing filter currently applied to the picture (S501). The video encoding device can encode the generated NNPF related information to generate an NNPF (Neural-network post-filter) related SEI message (S502). The video encoding device can transmit the generated NNPF related SEI message to, for example, the video decoding device (S503). The video encoding device performs steps S501 and S502, and step S503 may be part of a transmission method performed by another transmission device.

[0337] Referring to Figure 6, the video decoding device can receive NNPF-related SEI messages relating to the neural network post-processing filter currently applied to the picture (S601). The video decoding device can decode the received NNPF-related SEI messages to restore NNPF-related information (S602). The video decoding device can apply NNPF to the current picture based on the restored NNPF-related information (S603). Steps S602 and S603 may be performed on the condition that NNPF is applied to the current picture.

[0338] In the description with reference to Figures 5 and 6, the NNPF-related SEI message may include the NNPFC SEI message, the NNPFA SEI message, and / or the SEI message relating to the post-filter hint as per this disclosure. Furthermore, the NNPF-related information may mean the information signaled by the syntax elements included in the NNPF-related SEI message.

[0339] NNPF-related SEI messages may be transmitted in a predetermined unit. The predetermined unit may contain one or more pictures. The predetermined unit may be an AU, but is not limited thereto, and may be referred to as “unit information” in this disclosure.

[0340] Figure 7 is a flowchart illustrating other video encoding methods to which the embodiments of this disclosure can be applied.

[0341] Figure 8 is a flowchart illustrating other video decoding methods to which the embodiments of this disclosure can be applied.

[0342] The video encoding method shown in Figure 7 may be performed by the video encoding device 100, and the video decoding method shown in Figure 8 may be performed by the video decoding device 200.

[0343] Referring to Figure 7, the video encoding device can perform the steps of encoding the current picture (S701) and configuring unit information including the encoded current picture (S702).

[0344] The video encoding device can configure a bitstream containing the unit information and transmit the bitstream to the video decoding device. The video decoding device can receive the bitstream and obtain the unit information contained in the bitstream.

[0345] Specifically, referring to Figure 8, the video decoding device can perform the steps of acquiring unit information including the current picture (S801) and decoding the current picture based on the unit information (S802).

[0346] The embodiments and configurations relating to the NNPFC SEI messages and / or NNPFA SEI messages described herein may be applied to the video encoding method and / or video decoding method described herein with reference to Figures 7 and 8.

[0347] Specifically, in the video encoding method and / or video decoding method relating to this disclosure, the type of current picture may be restricted based on NNPF (neural-network post-filter) related SEI (supplemental enhancement information) messages contained in the unit information.

[0348] Furthermore, in the video encoding method and / or video decoding method relating to this disclosure, based on the fact that the unit information includes an NNPFA (neural-network post-filter activation) SEI message, the current picture may be limited to the output picture among the output picture and the non-output picture.

[0349] Furthermore, in the video encoding method and / or video decoding method relating to this disclosure, the unit information may be restricted so as not to include an NNPFA SEI message, based on the fact that the current picture is a non-output picture.

[0350] Furthermore, in the video encoding method and / or video decoding method relating to this disclosure, the unit information may be restricted so as not to include NNPFC (neural-network post-filter characteristics) SEI messages, based on the fact that the current picture is a discardable picture.

[0351] Furthermore, in the video encoding method and / or video decoding method relating to this disclosure, the NNPFC SEI messages included in the unit information may be restricted so as not to be associated with discardable pictures.

[0352] Furthermore, in the video encoding method and / or video decoding method relating to this disclosure, the NNPFA SEI message included in the unit information may be restricted so as not to be associated with a non-output picture.

[0353] Furthermore, in the video encoding method and / or video decoding method relating to this disclosure, the NNPF input picture activated by the NNPF-related SEI message may be restricted so as not to include discardable pictures.

[0354] The video encoding and decoding methods described with reference to Figures 7 and 8 may be combined with the video encoding and decoding methods described with reference to Figures 5 and 6. For example, a video encoding device performing the video encoding method of Figure 7 can generate NNPF-related SEI messages related to the current picture and transmit them to a video decoding device by performing the video encoding method of Figure 5. Furthermore, a video decoding device performing the video decoding method of Figure 8 can recover NNPF-related information from the NNPF-related SEI messages and then apply NNPF to the current picture by performing the video decoding method of Figure 6.

[0355] According to the embodiments of this disclosure, it is expected that when a discardable picture is discarded, NNPFC SEI messages included in the same AU will also be discarded. Furthermore, it is expected that pictures activated by NNPFA SEI messages will not be output. In addition, it is expected that cases will not occur where the list of input pictures in the encoder and the list of input pictures in the decoder do not match. Including these effects, it is expected that the additional problems of the prior art described above will be resolved.

[0356] Figure 9 illustrates a content streaming system to which the embodiments of this disclosure can be applied.

[0357] As shown in Figure 9, a content streaming system to which an embodiment of the present disclosure is applied may broadly include an encoding server, a streaming server, a web server, media storage, user equipment, and multimedia input devices.

[0358] The encoding server is responsible for compressing content input from multimedia input devices such as smartphones, cameras, and camcorders into digital data to generate a bitstream, and transmitting this bitstream to the streaming server. As another example, if a multimedia input device such as a smartphone, camera, or camcorder directly generates the bitstream, the encoding server may be omitted.

[0359] The bitstream may be generated by a video encoding method and / or video encoding apparatus to which an embodiment of the present disclosure is applied, and the streaming server may temporarily store the bitstream in the process of transmitting or receiving the bitstream.

[0360] The streaming server transmits multimedia data to user devices based on user requests via a web server, and the web server can act as an intermediary to inform users of available services. When a user requests a desired service from the web server, the web server transmits it to the streaming server, and the streaming server can transmit multimedia data to the user. In this case, the content streaming system may include a separate control server, in which case the control server can play a role in controlling commands and responses between the devices within the content streaming system.

[0361] The streaming server can receive content from media storage and / or encoding servers. For example, when receiving content from the encoding server, the content can be received in real time. In this case, in order to provide a smooth streaming service, the streaming server can store the bitstream for a certain period of time.

[0362] Examples of user devices include mobile phones, smartphones, laptop computers, digital broadcasting terminals, PDAs (personal digital assistants), PMPs (portable multimedia players), navigation systems, slate PCs, tablet PCs, ultrabooks, wearable devices (such as smartwatches, smart glasses, and HMDs), digital TVs, desktop computers, and digital signage.

[0363] Each server within the aforementioned content streaming system may be operated as a distributed server, in which case the data received by each server may be processed in a distributed manner.

[0364] The scope of this disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that enable the operation of various embodiments to be performed on a device or computer, and non-transitory computer-readable medium on which such software or instructions are stored and executable on a device or computer.

[0365] [Industrial applicability] The embodiments described herein can be used for encoding / decoding video.

[0366] [Claims when filing an international application] [Claim 1] A video decoding method performed by a video decoding device, Currently, we are in the stage of acquiring unit information including pictures. The process includes the step of decoding the current picture based on the unit information, A video decoding method in which the type of current picture is restricted based on NNPF (neural-network post-filter) related SEI (supplemental enhancement information) messages contained in the aforementioned unit information. [Claim 2] The video decoding method according to claim 1, wherein, based on the unit information including an NNPFA (neural-network post-filter activation) SEI message, the current picture is limited to an output picture among output pictures and non-output pictures. [Claim 3] The video decoding method according to claim 1, wherein, based on the fact that the current picture is a non-output picture, the unit information is restricted so as not to include an NNPFA SEI message. [Claim 4] The video decoding method according to claim 1, wherein, based on the fact that the current picture is a discardable picture, the unit information is restricted so as not to include NNPFC (neural-network post-filter characteristics) SEI messages. [Claim 5] The video decoding method according to claim 1, wherein the NNPFC SEI messages included in the unit information are restricted so as not to be associated with discardable pictures. [Claim 6] The video decoding method according to claim 1, wherein the NNPFA SEI message included in the unit information is restricted so as not to be associated with a non-output picture. [Claim 7] The video decoding method according to claim 1, wherein the NNPF input picture activated by the NNPF-related SEI message is restricted so as not to include discardable pictures. [Claim 8] A video encoding method performed by a video encoding device, Currently, we are in the stage of encoding the picture, The process includes the step of constructing unit information including the encoded current picture, A video encoding method in which the type of current picture is restricted based on NNPF (neural-network post-filter) related SEI (supplemental enhancement information) messages contained in the aforementioned unit information. [Claim 9] The video encoding method according to claim 8, wherein, based on the unit information including an NNPFA (neural-network post-filter activation) SEI message, the current picture is restricted to an output picture among output pictures and non-output pictures. [Claim 10] The video encoding method according to claim 8, wherein the unit information is restricted to not include an NNPFA SEI message based on the fact that the current picture is a non-output picture. [Claim 11] The video encoding method according to claim 8, wherein, based on the fact that the current picture is a discardable picture, the unit information is restricted so as not to include NNPFC (neural-network post-filter characteristics) SEI messages. [Claim 12] The video encoding method according to claim 8, wherein the NNPFC SEI messages included in the unit information are restricted so as not to be associated with discardable pictures. [Claim 13] The video encoding method according to claim 8, wherein the NNPFA SEI message included in the unit information is restricted so as not to be associated with a non-output picture. [Claim 14] The video encoding method according to claim 8, wherein the NNPF input picture activated by the NNPF-related SEI message is restricted so as not to include discardable pictures. [Claim 15] A computer-readable recording medium for storing a bitstream generated by a video encoding method, The aforementioned video encoding method is Currently, we are in the stage of encoding the picture, The process includes the step of constructing unit information including the encoded current picture, A recording medium in which the type of picture is currently restricted based on NNPF (neural-network post-filter) related SEI (supplemental enhancement information) messages contained in the aforementioned unit information. [Claim 16] A method for transmitting a bitstream generated by a video encoding method, The aforementioned video encoding method is Currently, we are in the stage of encoding the picture, The process includes the step of constructing unit information including the encoded current picture, A method in which the type of current picture is restricted based on NNPF (neural-network post-filter) related SEI (supplemental enhancement information) messages contained in the unit information.

Claims

1. A video decoding method performed by a video decoding device, Currently, we are in the stage of acquiring unit information including pictures, The process includes the step of decoding the current picture based on the unit information, A video decoding method in which the type of the current picture is restricted based on an NNPF (neutral-network post-filter) related SEI (supplemental enhancement information) message contained in the unit information.

2. The video decoding method according to claim 1, wherein, based on the unit information including an NNPFA (neural-network post-filter activation) SEI message, the current picture is limited to an output picture among output pictures and non-output pictures.

3. The video decoding method according to claim 1, wherein, based on the fact that the current picture is a non-output picture, the unit information is restricted so as not to include an NNPFA SEI message.

4. The video decoding method according to claim 1, wherein, based on the fact that the current picture is a discardable picture, the unit information is restricted so as not to include NNPFC (neural-network post-filter characteristics) SEI messages.

5. The video decoding method according to claim 1, wherein the NNPFC SEI messages included in the unit information are restricted so as not to be associated with discardable pictures.

6. The video decoding method according to claim 1, wherein the NNPFA SEI message included in the unit information is restricted so as not to be associated with a non-output picture.

7. The video decoding method according to claim 1, wherein the input picture of the NNPF activated by the NNPF-related SEI message is restricted so as not to include discardable pictures.

8. A video encoding method performed by a video encoding device, Currently, we are in the stage of encoding the picture, The process includes the step of constructing unit information including the encoded current picture, A video encoding method in which the type of current picture is restricted based on an NNPF (neutral-network post-filter) related SEI (supplemental enhancement information) message contained in the unit information.

9. The video encoding method according to claim 8, wherein the current picture is limited to an output picture among output pictures and non-output pictures, based on the unit information including an NNPFA (neural-network post-filter activation) SEI message.

10. The video encoding method according to claim 8, wherein, based on the fact that the current picture is a non-output picture, the unit information is restricted so as not to include an NNPFA SEI message.

11. The video encoding method according to claim 8, wherein, based on the fact that the current picture is a discardable picture, the unit information is restricted so as not to include NNPFC (neural-network post-filter characteristics) SEI messages.

12. The video encoding method according to claim 8, wherein the NNPFC SEI messages included in the unit information are restricted from being associated with discardable pictures.

13. The video encoding method according to claim 8, wherein the NNPFA SEI message included in the unit information is restricted so as not to be associated with a non-output picture.

14. The video encoding method according to claim 8, wherein the input picture of the NNPF activated by the NNPF-related SEI message is restricted so as not to include discardable pictures.

15. A computer-readable recording medium for storing a bitstream generated by a video encoding method, The aforementioned video encoding method is Currently, we are in the stage of encoding the picture, The process includes the step of constructing unit information including the encoded current picture, A recording medium in which the type of current picture is restricted based on an NNPF (neutral-network post-filter) related SEI (supplemental enhancement information) message contained in the unit information.

16. A method for transmitting a bitstream generated by a video encoding method, The aforementioned video encoding method is Currently, we are in the stage of encoding the picture, The process includes the step of constructing unit information including the encoded current picture, A method in which the current picture type is restricted based on an NNPF (neutral-network post-filter) related SEI (supplemental enhancement information) message contained in the unit information.

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