Image encoding / decoding method and apparatus, and recording medium for storing bitstream

Abstract

An image encoding method and apparatus according to the present disclosure can receive a video picture to be encoded, encode the received video picture to generate a compressed video picture, generate encoder optimization information, and generate a bitstream including the compressed video picture and the encoder optimization information. The encoder optimization information may include size information of the original picture, and the size information of the original picture may be generated on the basis of a flag indicating whether information related to the original picture exists.

Description

Video encoding / decoding method and device, and recording medium storing bitstream

[0001] The present invention relates to a video encoding / decoding method and device, and a recording medium storing a bitstream.

[0002] Recently, the demand for high-resolution, high-quality images, such as HD (High Definition) images and UHD (Ultra High Definition) images, is increasing in various application fields, and accordingly, high-efficiency image compression technologies are being discussed.

[0003] There are various technologies for image compression, such as inter prediction technology that predicts pixel values ​​included in the current picture from pictures before or after the current picture, intra prediction technology that predicts pixel values ​​included in the current picture using pixel information in the current picture, and entropy encoding technology that assigns short codes to values ​​with high frequency of appearance and long codes to values ​​with low frequency of appearance, and these technologies can be used to effectively compress and transmit or store image data.

[0004] The present disclosure provides a method and apparatus for configuring encoder optimization information.

[0005] The present disclosure provides a method and apparatus for signaling encoder optimization information.

[0006] A video encoding method and device according to the present disclosure can receive a video picture to be encoded, encode the received video picture to generate a compressed video picture, generate encoder optimization information, and generate a bitstream including the compressed video picture and the encoder optimization information.

[0007] In the video encoding method and device according to the present disclosure, the encoder optimization information may include size information of the original picture.

[0008] In the image encoding method and device according to the present disclosure, the size information of the original picture can be generated based on a flag indicating whether information related to the original picture exists.

[0009] In the video encoding method and device according to the present disclosure, the size information of the original picture may include information indicating the width of the original picture and information indicating the height of the original picture.

[0010] In the video encoding method and device according to the present disclosure, when the value of the flag is 1, information related to the original picture may exist, and when the value of the flag is 0, information related to the original picture may not exist.

[0011] In the video encoding method and device according to the present disclosure, based on the value of the flag being 1, information indicating the width of the original picture and information indicating the height of the original picture can be generated, respectively.

[0012] In the video encoding method and device according to the present disclosure, based on the value of the flag being 0, information indicating the width of the original picture and information indicating the height of the original picture may not be generated.

[0013] In the video encoding method and device according to the present disclosure, a spatial resampling type identifier for identifying the type of applied spatial resampling can be generated based on the value of the flag being 0.

[0014] In the video encoding method and device according to the present disclosure, the flag may be generated based on a spatial resampling flag indicating whether spatial resampling optimization has been applied.

[0015] In the video encoding method and device according to the present disclosure, the spatial resampling flag can be derived based on EOI type information regarding properties of an optimization method.

[0016] A video decoding method and device according to the present disclosure can receive a bitstream including an encoded video picture and restore the encoded video picture included in the bitstream. Here, the bitstream can include encoder optimization information, and the encoder optimization information can include size information of an original picture. The size information of the original picture can be included based on a flag indicating whether information related to the original picture exists.

[0017] A computer-readable digital storage medium is provided, which stores encoded video / image information that causes a decoding device according to the present disclosure to perform a video decoding method.

[0018] A computer-readable digital storage medium storing video / image information generated by a video encoding method according to the present disclosure is provided.

[0019] A method and device for transmitting video / image information generated by a video encoding method according to the present disclosure are provided.

[0020] According to the present disclosure, by configuring the size information of the original picture into the encoder optimization information, the properties of the applied spatial resampling can be identified.

[0021] According to the present disclosure, detailed information regarding spatial resampling optimization can be efficiently signaled.

[0022] FIG. 1 illustrates a video / image coding system according to the present disclosure.

[0023] FIG. 2 is a schematic block diagram of an encoding device to which an embodiment of the present disclosure can be applied and in which encoding of a video / image signal is performed.

[0024] FIG. 3 is a schematic block diagram of a decoding device to which an embodiment of the present disclosure can be applied and in which decoding of a video / image signal is performed.

[0025] FIG. 4 illustrates a method for generating a bitstream performed in an encoding device (200) according to the present disclosure.

[0026] FIG. 5 illustrates a schematic configuration of an encoding device (200) that performs a method for generating a bitstream according to the present disclosure.

[0027] FIG. 6 illustrates a method for restoring a video picture performed in a decoding device (300) according to the present disclosure.

[0028] FIG. 7 illustrates a schematic configuration of a decoding device (300) that performs a method for restoring a video picture according to the present disclosure.

[0029] FIG. 8 illustrates an example of a content streaming system to which embodiments of the present disclosure can be applied.

[0030] The present disclosure may be modified in various ways and encompasses numerous embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present disclosure to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present disclosure. Similar reference numerals have been used to designate similar components throughout the description of each drawing.

[0031] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present disclosure, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component." The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0032] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0033] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0034] The present disclosure relates to video / image coding. For example, the methods / embodiments disclosed in this specification can be applied to methods disclosed in the versatile video coding (VVC) standard. In addition, the methods / embodiments disclosed in this specification can be applied to methods disclosed in the essential video coding (EVC) standard, the AOMedia Video 1 (AV1) standard, the second generation of audio video coding standard (AVS2), or the next generation of video / image coding standards (e.g., H.267 or H.268).

[0035] This specification presents various embodiments of video / image coding, and unless otherwise stated, the embodiments may be performed in combination with each other.

[0036] In this specification, a video may refer to a set of images over time. A picture generally refers to a unit representing one image at a specific time point, and a slice / tile is a unit that constitutes part of a picture in coding. A slice / tile may include one or more coding tree units (CTUs). A picture may be composed of one or more slices / tiles. A tile is a rectangular area consisting of multiple CTUs within a specific tile column and a specific tile row of a picture. A tile column is a rectangular area of ​​CTUs that has a height equal to the height of the picture and a width specified by the syntax requirements of the picture parameter set. A tile row is a rectangular area of ​​CTUs that has a height specified by the picture parameter set and a width equal to the width of the picture. CTUs within a tile are arranged consecutively according to the CTU raster scan, while tiles within a picture may be arranged consecutively according to the tile raster scan. A slice may contain an integer number of complete tiles or an integer number of contiguous complete CTU rows within a picture, which may be exclusively contained within a single NAL unit. Meanwhile, a picture may be divided into two or more subpictures. A subpicture may be a rectangular region of one or more slices within a picture.

[0037] A pixel, or pel, can refer to the smallest unit that constitutes a picture (or image). Additionally, the term "sample" can be used as a counterpart to a pixel. A sample can generally represent a pixel or a pixel value, and can represent only the pixel / pixel value of the luminance component, or only the pixel / pixel value of the chrominance component.

[0038] A 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 related to the region. One unit may include one luma block and two chroma (e.g., cb, cr) blocks. In some cases, the term "unit" may be used interchangeably with terms such as "block" or "area." In general, an MxN block may include a set (or array) of samples (or sample array) or transform coefficients consisting of M columns and N rows.

[0039] As used herein, "A or B" can mean "only A," "only B," or "both A and B." In other words, as used herein, "A or B" can be interpreted as "A and / or B." For example, as used herein, "A, B or C" can mean "only A," "only B," "only C," or "any combination of A, B and C."

[0040] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0041] In this specification, "at least one of A and B" may mean "only A", "only B" or "both A and B". Additionally, in this specification, the expressions "at least one of A or B" or "at least one of A and / or B" may be interpreted identically to "at least one of A and B".

[0042] Additionally, in this specification, “at least one of A, B and C” can mean “only A,” “only B,” “only C,” or “any combination of A, B and C.” Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C.”

[0043] Additionally, parentheses used herein may mean "for example." Specifically, when "prediction (intra-prediction)" is indicated, "intra-prediction" may be suggested as an example of "prediction." In other words, "prediction" in this specification is not limited to "intra-prediction," and "intra-prediction" may be suggested as an example of "prediction." Furthermore, even when "prediction (i.e., intra-prediction)" is indicated, "intra-prediction" may be suggested as an example of "prediction."

[0044] Technical features individually described in a single drawing in this specification may be implemented individually or simultaneously.

[0045] FIG. 1 illustrates a video / image coding system according to the present disclosure.

[0046] Referring to FIG. 1, a video / image coding system may include a first device (source device) and a second device (receiving device).

[0047] A source device can transmit encoded video / image information or data to a receiving device via a digital storage medium or a network in the form of a file or streaming. The source device may include a video source, an encoding device, and a transmitting device. The receiving device may include a receiving device, a decoding device, and a renderer. The encoding device may be referred to as a video / image encoding device, and the decoding device may be referred to as a video / image decoding device. The transmitter may be included in the encoding device. The receiver may be included in the decoding device. The renderer may include a display unit, and the display unit may be configured as a separate device or an external component.

[0048] A video source may obtain video / images through a process of capturing, synthesizing, or generating video / images. The video source may include a video / image capture device and / or a video / image generation device. The video / image capture device may include one or more cameras, a video / image archive containing previously captured video / images, etc. The video / image generation device may include a computer, a tablet, a smartphone, etc., and may (electronically) generate video / images. For example, a virtual video / image may be generated through a computer, etc., in which case the video / image capture process may be replaced by a process of generating related data.

[0049] An encoding device can encode input video / images. The encoding device can perform a series of procedures, such as prediction, transformation, and quantization, to improve compression and coding efficiency. The encoded data (encoded video / image information) can be output in the form of a bitstream.

[0050] The transmission unit can transmit encoded video / image information or data output in the form of a bitstream to the receiving unit of a receiving device via a digital storage medium or network in the form of a file or streaming. The digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmission unit can include an element for generating a media file via a predetermined file format and an element for transmission via a broadcasting / communication network. The receiving unit can receive / extract the bitstream and transmit it to a decoding device.

[0051] The decoding device can decode the video / image by performing a series of procedures such as inverse quantization, inverse transformation, and prediction corresponding to the operation of the encoding device.

[0052] The renderer can render decoded video / images. The rendered video / images can be displayed through the display unit.

[0053] FIG. 2 is a schematic block diagram of an encoding device to which an embodiment of the present disclosure can be applied and in which encoding of a video / image signal is performed.

[0054] Referring to FIG. 2, the encoding device (200) may be configured to include an image partitioner (210), a prediction unit (predictor) 220, a residual processor (residual processor) 230, an entropy encoder (entropy encoder) 240, an adder (adder) 250, a filter (filter) 260, and a memory (memory) 270. The prediction unit (220) may include an inter prediction unit (221) and an intra prediction unit (222). The residual processor (230) may include a transformer (transformer) 232, a quantizer (quantizer) 233, a dequantizer (dequantizer) 234, and an inverse transformer (inverse transformer) 235. The residual processing unit (230) may further include a subtractor (231). The addition unit (250) may be called a reconstructor or a recontructed block generator. The image segmentation unit (210), the prediction unit (220), the residual processing unit (230), the entropy encoding unit (240), the addition unit (250), and the filtering unit (260) described above may be configured by one or more hardware components (e.g., an encoding device chipset or processor) according to an embodiment. In addition, the memory (270) may include a decoded picture buffer (DPB) and may be configured by a digital storage medium. The hardware component may further include the memory (270) as an internal / external component.

[0055] The image segmentation unit (210) can segment an input image (or picture, frame) input to the encoding device (200) into one or more processing units. For example, the processing unit may be called a coding unit (CU). In this case, the coding unit may be recursively segmented from a coding tree unit (CTU) or a largest coding unit (LCU) according to a QTBTTT (Quad-tree binary-tree ternary-tree) structure.

[0056] For example, a single coding unit may be split into multiple coding units with deeper depths based on a quad-tree structure, a binary tree structure, and / or a ternary structure. In this case, for example, the quad-tree structure may be applied first, and the binary tree structure and / or the ternary structure may be applied later. Alternatively, the binary tree structure may be applied before the quad-tree structure. The coding procedure according to the present specification may be performed based on the final coding unit that is no longer split. In this case, based on coding efficiency according to image characteristics, etc., the largest coding unit may be used directly as the final coding unit, or, if necessary, the coding unit may be recursively split into coding units of lower depths, and the coding unit with the optimal size may be used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and restoration, which will be described later.

[0057] As another example, the processing unit may further include a prediction unit (PU) or a transform unit (TU). In this case, the prediction unit and the transform unit may each be split or partitioned from the final coding unit described above. The prediction unit may be a unit of sample prediction, and the transform unit may be a unit for deriving a transform coefficient and / or a unit for deriving a residual signal from a transform coefficient.

[0058] The term "unit" may be used interchangeably with terms such as "block" or "area" depending on the case. In general, an MxN block can represent a set of samples or transform coefficients consisting of M columns and N rows. A sample can generally represent a pixel or a pixel value, and can represent only the pixel / pixel value of the luminance component, or only the pixel / pixel value of the chrominance component. A sample can be used as a term corresponding to a pixel or pel in a picture (or image).

[0059] The encoding device (200) can generate a residual signal (residual block, residual sample array) by subtracting a prediction signal (prediction block, prediction sample array) output from an inter prediction unit (221) or an intra prediction unit (222) from an input video signal (original block, original sample array), and the generated residual signal is transmitted to a conversion unit (232). In this case, a unit that subtracts a prediction signal (prediction block, prediction sample array) from an input video signal (original block, original sample array) within the encoding device (200) may be called a subtraction unit (231).

[0060] The prediction unit (220) can perform a prediction on a block to be processed (hereinafter, referred to as a current block) and generate a predicted block including prediction samples for the current block. The prediction unit (220) can determine whether intra prediction or inter prediction is applied on a current block or CU basis. The prediction unit (220) can generate various information related to prediction, such as prediction mode information, as described later in the description of each prediction mode, and transmit the information to the entropy encoding unit (240). The information related to prediction can be encoded by the entropy encoding unit (240) and output in the form of a bitstream.

[0061] The intra prediction unit (222) can predict the current block by referring to samples in the current picture. The referenced samples may be located in the neighborhood of the current block, or may be located a certain distance away from the current block, depending on the prediction mode. In intra prediction, the prediction modes may include one or more non-directional modes and multiple directional modes. The non-directional mode may include at least one of a DC mode or a planar mode. The directional mode may include 33 directional modes or 65 directional modes depending on the degree of detail in the prediction direction. However, this is only an example, and a greater or lesser number of directional modes may be used depending on the settings. The intra prediction unit (222) may also determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0062] The inter prediction unit (221) can derive a prediction block for the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. At this time, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information can be predicted in units of blocks, subblocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information can include a motion vector and a reference picture index. The motion information can further include inter prediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring block can include a spatial neighboring block existing in the current picture and a temporal neighboring block existing in the reference picture. The reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different. The above temporal neighboring blocks may be called collocated reference blocks, collocated CUs (colCUs), etc., and the reference pictures including the temporal neighboring blocks may be called collocated pictures (colPic). For example, the inter prediction unit (221) may construct a motion information candidate list based on the neighboring blocks, and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Inter prediction may be performed based on various prediction modes, and for example, in the case of skip mode and merge mode, the inter prediction unit (221) may use the motion information of the neighboring blocks as the motion information of the current block. In the case of skip mode, unlike the merge mode, a residual signal may not be transmitted.In the motion vector prediction (MVP) mode, the motion vector of the surrounding blocks is used as a motion vector predictor, and the motion vector of the current block can be indicated by signaling the motion vector difference.

[0063] The prediction unit (220) can generate a prediction signal based on various prediction methods described below. For example, the prediction unit can apply intra prediction or inter prediction for prediction of a single block, and can also apply intra prediction and inter prediction simultaneously. This can be called combined inter and intra prediction (CIIP) mode. In addition, the prediction unit can be based on an intra block copy (IBC) prediction mode or a palette mode for prediction of a block. The IBC prediction mode or palette mode can be used for content image / video coding such as games, such as screen content coding (SCC). IBC basically performs prediction within the current picture, but can be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC can utilize at least one of the inter prediction techniques described herein. Palette mode can be viewed as an example of intra coding or intra prediction. When the palette mode is applied, sample values ​​within a picture can be signaled based on information about the palette table and palette index. The prediction signal generated through the prediction unit (220) can be used to generate a restoration signal or a residual signal.

[0064] The transform unit (232) can apply a transform technique to the residual signal to generate transform coefficients. For example, the transform technique can include at least one of a Discrete Cosine Transform (DCT), a Discrete Sine Transform (DST), a Karhunen-Loeve Transform (KLT), a Graph-Based Transform (GBT), or a Conditionally Non-linear Transform (CNT). Here, GBT refers to a transform obtained from a graph when the relationship information between pixels is expressed as a graph. CNT refers to a transform obtained based on generating a prediction signal using all previously restored pixels. In addition, the transform process can be applied to a pixel block having a square size and the same size, or can be applied to a block of a non-square variable size.

[0065] The quantization unit (233) quantizes the transform coefficients and transmits them to the entropy encoding unit (240), and the entropy encoding unit (240) can encode the quantized signal (information about the quantized transform coefficients) and output it as a bitstream. The information about the quantized transform coefficients can be called residual information. The quantization unit (233) can rearrange the quantized transform coefficients in a block form into a one-dimensional vector form based on the coefficient scan order, and can also generate information about the quantized transform coefficients based on the quantized transform coefficients in the one-dimensional vector form.

[0066] The entropy encoding unit (240) can perform various encoding methods such as exponential Golomb, context-adaptive variable length coding (CAVLC), context-adaptive binary arithmetic coding (CABAC), etc. The entropy encoding unit (240) can also encode information necessary for video / image restoration (e.g., values ​​of syntax elements, etc.) together or separately from quantized transform coefficients.

[0067] Encoded information (e.g., encoded video / image information) can 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 on 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). In addition, the video / image information may further include general constraint information. In the present specification, information and / or syntax elements transmitted / signaled from an encoding device to a decoding device may be included in the video / image information. The video / image information may be encoded through the above-described encoding procedure and included in the bitstream. The bitstream may be transmitted via a network or stored in a digital storage medium. Here, the network may include a broadcasting network and / or a communication network, and the digital storage medium may include various storage media, such as a USB, SD, CD, DVD, Blu-ray, HDD, or SSD. The signal output from the entropy encoding unit (240) may be configured as an internal / external element of the encoding device (200) by a transmitting unit (not shown) and / or a storing unit (not shown), or the transmitting unit may be included in the entropy encoding unit (240).

[0068] The quantized transform coefficients output from the quantization unit (233) can be used to generate a prediction signal. For example, by applying inverse quantization and inverse transformation to the quantized transform coefficients through the inverse quantization unit (234) and the inverse transform unit (235), a residual signal (residual block or residual samples) can be restored. The addition unit (250) can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the reconstructed residual signal to the prediction signal output from the inter prediction unit (221) or the intra prediction unit (222). When there is no residual for the block to be processed, such as when skip mode is applied, the predicted block can be used as a reconstructed block. The addition unit (250) may be called a restoration unit or a reconstructed block generation unit. The generated restoration signal can be used for intra prediction of the next processing target block within the current picture, and can also be used for inter prediction of the next picture after filtering as described below. Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture encoding and / or restoration process.

[0069] The filtering unit (260) can improve subjective / objective picture quality by applying filtering to the restoration signal. For example, the filtering unit (260) can apply various filtering methods to the restoration picture to generate a modified restoration picture, and store the modified restoration picture in the memory (270), specifically, in the DPB of the memory (270). The various filtering methods can include deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc. The filtering unit (260) can generate various information regarding filtering and transmit it to the entropy encoding unit (240). The information regarding filtering can be encoded by the entropy encoding unit (240) and output in the form of a bitstream.

[0070] The modified restored picture transmitted to the memory (270) can be used as a reference picture in the inter prediction unit (221). Through this, when inter prediction is applied, the encoding device can avoid prediction mismatch between the encoding device (200) and the decoding device, and can also improve encoding efficiency.

[0071] The DPB of the memory (270) can store the modified restored picture to be used as a reference picture in the inter prediction unit (221). The memory (270) can store motion information of a block from which motion information is derived (or encoded) within the current picture and / or motion information of blocks within a picture that has already been restored. The stored motion information can be transferred to the inter prediction unit (221) to be used as motion information of a spatial neighboring block or motion information of a temporal neighboring block. The memory (270) can store restored samples of restored blocks within the current picture and transfer them to the intra prediction unit (222).

[0072] FIG. 3 is a schematic block diagram of a decoding device to which an embodiment of the present disclosure can be applied and in which decoding of a video / image signal is performed.

[0073] Referring to FIG. 3, the decoding device (300) may be configured to include an entropy decoder (310), a residual processor (320), a predictor (330), an adder (340), a filter (350), and a memory (360). The predictor (330) may include an inter-prediction unit (332) and an intra-prediction unit (331). The residual processor (320) may include a dequantizer (321) and an inverse transformer (321).

[0074] The entropy decoding unit (310), residual processing unit (320), prediction unit (330), addition unit (340), and filtering unit (350) described above may be configured by a single hardware component (e.g., a decoding device chipset or processor) depending on the embodiment. In addition, the memory (360) may include a decoded picture buffer (DPB) and may be configured by a digital storage medium. The hardware component may further include the memory (360) as an internal / external component.

[0075] When a bitstream including video / image information is input, the decoding device (300) can restore the image corresponding to the process in which the video / image information is processed in the encoding device of FIG. 2. For example, the decoding device (300) can derive units / blocks based on block division-related information obtained from the bitstream. The decoding device (300) can perform decoding using a processing unit applied in the encoding device. Accordingly, the processing unit for decoding may be a coding unit, and the coding unit may be divided from a coding tree unit or a maximum coding unit according to a quad tree structure, a binary tree structure, and / or a ternary tree structure. One or more transform units may be derived from the coding unit. Then, the restored image signal decoded and output by the decoding device (300) can be reproduced through a reproduction device.

[0076] The decoding device (300) can receive a signal output from the encoding device of FIG. 2 in the form of a bitstream, and the received signal can be decoded through the entropy decoding unit (310). For example, the entropy decoding unit (310) can parse the bitstream to derive information (e.g., video / image information) necessary for image restoration (or picture restoration). The video / image information may further include information on 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). In addition, the video / image information may further include general constraint information. The decoding device can decode the picture further based on the information on the parameter set and / or the general constraint information. The signaling / received information and / or syntax elements described later in this specification can be decoded through the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit (310) can decode information in a bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and output the values ​​of syntax elements required for image restoration and the quantized values ​​of transform coefficients for residuals. More specifically, the CABAC entropy decoding method receives a bin corresponding to each syntax element in the bitstream, determines a context model using information of the syntax element to be decoded and decoding information of the surrounding and decoding target blocks or information of symbols / bins decoded in the previous step, and predicts the occurrence probability of the bin according to the determined context model to perform arithmetic decoding of the bin to generate a symbol corresponding to the value of each syntax element.At this time, the CABAC entropy decoding method can update the context model using the information of the decoded symbol / bin for the context model of the next symbol / bin after determining the context model. Information regarding prediction among the information decoded by the entropy decoding unit (310) is provided to the prediction unit (inter prediction unit (332) and intra prediction unit (331)), and residual values ​​on which entropy decoding is performed by the entropy decoding unit (310), i.e., quantized transform coefficients and related parameter information, can be input to the residual processing unit (320). The residual processing unit (320) can derive a residual signal (residual block, residual samples, residual sample array). In addition, information regarding filtering among the information decoded by the entropy decoding unit (310) can be provided to the filtering unit (350). Meanwhile, a receiving unit (not shown) that receives a signal output from an encoding device may be further configured as an internal / external element of a decoding device (300), or the receiving unit may be a component of an entropy decoding unit (310).

[0077] Meanwhile, a decoding device according to the present specification may be called a video / video / picture decoding device, and the decoding device may be divided into an information decoding device (video / video / picture information decoding device) and a sample decoding device (video / video / picture sample decoding device). The information decoding device may include the entropy decoding unit (310), and the sample decoding device may include at least one of the inverse quantization unit (321), the inverse transformation unit (322), the addition unit (340), the filtering unit (350), the memory (360), the inter prediction unit (332), and the intra prediction unit (331).

[0078] The inverse quantization unit (321) can inverse quantize the quantized transform coefficients and output the transform coefficients. The inverse quantization unit (321) can rearrange the quantized transform coefficients into a two-dimensional block form. In this case, the rearrangement can be performed based on the coefficient scanning order performed in the encoding device. The inverse quantization unit (321) can perform inverse quantization on the quantized transform coefficients using quantization parameters (e.g., quantization step size information) and obtain transform coefficients.

[0079] In the inverse transform unit (322), the transform coefficients are inversely transformed to obtain a residual signal (residual block, residual sample array).

[0080] The prediction unit (320) can perform a prediction on the current block and generate a predicted block including prediction samples for the current block. The prediction unit (320) can determine whether intra-prediction or inter-prediction is applied to the current block based on the information regarding the prediction output from the entropy decoding unit (310), and can determine a specific intra / inter-prediction mode.

[0081] The prediction unit (320) can generate a prediction signal based on various prediction methods described below. For example, the prediction unit (320) can apply intra prediction or inter prediction for prediction of a single block, and can also apply intra prediction and inter prediction simultaneously. This can be called combined inter and intra prediction (CIIP) mode. In addition, the prediction unit can be based on an intra block copy (IBC) prediction mode or a palette mode for prediction of a block. The IBC prediction mode or palette mode can be used for content image / video coding such as games, such as screen content coding (SCC). IBC basically performs prediction within the current picture, but can be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC can utilize at least one of the inter prediction techniques described herein. Palette mode can be viewed as an example of intra coding or intra prediction. When palette mode is applied, information about the palette table and palette index may be included and signaled in the video / image information.

[0082] The intra prediction unit (331) can predict the current block by referring to samples within the current picture. The referenced samples may be located in the neighborhood of the current block, or may be located a certain distance away from the current block, depending on the prediction mode. In intra prediction, the prediction modes may include one or more non-directional modes and multiple directional modes. The intra prediction unit (331) may also determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0083] The inter prediction unit (332) can derive a prediction block for the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. At this time, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information can be predicted in units of blocks, subblocks, or samples based on the correlation of the motion information between the neighboring blocks and the current block. The motion information can include a motion vector and a reference picture index. The motion information can further include inter prediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring blocks can include spatial neighboring blocks existing in the current picture and temporal neighboring blocks existing in the reference picture. For example, the inter prediction unit (332) can construct a motion information candidate list based on the neighboring blocks, and derive the motion vector and / or reference picture index of the current block based on the received candidate selection information. Inter prediction can be performed based on various prediction modes, and information about the prediction can include information indicating an inter prediction mode for the current block.

[0084] The addition unit (340) can generate a restoration signal (restored picture, restoration block, restoration sample array) by adding the acquired residual signal to the prediction signal (prediction block, prediction sample array) output from the prediction unit (including the inter-prediction unit (332) and / or intra-prediction unit (331)). When there is no residual for the block to be processed, such as when skip mode is applied, the prediction block can be used as the restoration block.

[0085] The addition unit (340) may be referred to as a restoration unit or restoration block generation unit. The generated restoration signal may be used for intra prediction of the next processing target block within the current picture, may be output after filtering as described below, or may be used for inter prediction of the next picture. Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture decoding process.

[0086] The filtering unit (350) can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit (350) can apply various filtering methods to the restored picture to generate a modified restored picture, and transmit the modified restored picture to the memory (360), specifically, to the DPB of the memory (360). The various filtering methods can include deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc.

[0087] The (corrected) reconstructed picture stored in the DPB of the memory (360) can be used as a reference picture in the inter prediction unit (332). The memory (360) can store motion information of a block from which motion information is derived (or decoded) in the current picture and / or motion information of blocks in a picture that has already been reconstructed. The stored motion information can be transferred to the inter prediction unit (332) to be used as motion information of a spatial neighboring block or motion information of a temporal neighboring block. The memory (360) can store reconstructed samples of reconstructed blocks in the current picture and transfer them to the intra prediction unit (331).

[0088] In this specification, the embodiments described in the filtering unit (260), the inter prediction unit (221), and the intra prediction unit (222) of the encoding device (200) can be applied to the filtering unit (350), the inter prediction unit (332), and the intra prediction unit (331) of the decoding device (300) in the same or corresponding manner, respectively.

[0089] FIG. 4 illustrates a method for generating a bitstream performed in an encoding device (200) according to the present disclosure.

[0090] A video picture to be encoded can be received (S400).

[0091] A received video picture can be encoded to generate a compressed video picture (S410).

[0092] Encoder optimization information (EOI) can be generated (S420).

[0093] Encoder optimization information according to the present disclosure may relate to a received or compressed video picture. The encoder optimization information may define the purpose, properties, and scope (or target) of encoder optimization.

[0094] For example, encoder optimization information may include an EOI cancellation flag (eoi_cancel_flag). eoi_cancel_flag may relate to the persistence of encoder optimization information. If the value of eoi_cancel_flag is 1, this may indicate that the persistence of previously applied encoder optimization information is canceled. For example, if the value of eoi_cancel_flag is 1, this may indicate that the persistence of encoder optimization information included in a previous prediction unit (PU) in the output order is canceled. If the value of eoi_cancel_flag is 0, this may indicate that optimization-related information applied during pre-processing or encoding follows.

[0095] The above optimization-related information may include at least one of an EOI persistence flag (eoi_persistence_flag), an EOI identifier for human viewing (eoi_for_human_viewing_idc), an EOI identifier for machine analysis (eoi_for_machine_analysis_idc), or EOI type information (eoi_type). That is, the above-described optimization-related information may be encoded based on the value of eoi_cancel_flag being 0.

[0096] eoi_persistence_flag may be related to the persistence of optimization information. eoi_persistence_flag may indicate the persistence of the optimization information indicated by eoi_type. If the value of eoi_persistence_flag is 0, this may indicate that the optimization information (identified based on eoi_type) is applied only to the current picture. If the value of eoi_persistence_flag is 1, this may indicate that the optimization information (identified by eoi_type) is applied to the current picture and all subsequent pictures. Here, the subsequent pictures may mean all subsequent pictures of the current layer in output order.

[0097] eoi_for_human_viewing_idc can indicate information for identifying the purpose and target of optimization. A value of 3 for eoi_for_human_viewing_idc may indicate that the purpose of optimization includes human viewing. A value of 2 for eoi_for_human_viewing_idc may indicate that the video is suitable for human viewing but is not specifically optimized for human viewing. A value of 1 for eoi_for_human_viewing_idc may indicate that the video is not suitable for human viewing. A value of 0 for eoi_for_human_viewing_idc may indicate that it is unknown whether the video is suitable for human viewing.

[0098] eoi_for_machine_analysis_idc can indicate information for identifying the purpose and target of optimization. If the value of eoi_for_machine_analysis_idc is 3, this may mean that the purpose of optimization includes machine analysis. If the value of eoi_for_machine_analysis_idc is 2, this may mean that the video is suitable for machine analysis but is not specifically optimized for machine analysis. If the value of eoi_for_machine_analysis_idc is 1, this may mean that the video is not suitable for machine analysis. If the value of eoi_for_machine_analysis_idc is 0, this may mean that it is not known whether the video is suitable for machine analysis.

[0099] eoi_type can indicate the properties of an optimization method. For example, eoi_type can be defined as shown in Table 1 below. eoi_type can identify the optimization properties (or optimization types) defined in Table 1. However, the optimization properties defined in Table 1 are only examples, and new optimization properties may be defined under the structure. Alternatively, eoi_type can identify only some of the optimization properties defined in Table 1. Other optimization properties not defined in Table 1 may be additionally defined in Table 1.

[0100] bitMaskInterpretation0x01Object-based optimization; the pictures for which this SEI message persists have been pre-processed or encoded so that detected objects in the pictures are optimized with respect to other parts of the pictures for the indicated optimization purposes0x02Temporal resampling optimization0x04Spatial resampling optimization0x08Temporal quality optimization0x10Spatial quality optimization; the pictures for which this SEI message persists have been pre-processed or encoded to reduce unnecessary information or improve the quality of necessary information.(e.g to reduce the amount of noise and remove speckles at the picture-level)0x20personal information protection optimization; the pictures for which this SEI message persists have been pre-processed or encoded to protect personal information. (e.g. removal or replacing of personal identifiable information, pseudonymization, anonymization)

[0101] If (eoi_type & bitMask) is not 0, this may indicate that an optimization property with the bitMask value in Table 1 has been applied. If eoi_type is greater than 0 and (eoi_type & bitMask) is 0, this may indicate that an optimization property with the corresponding bitMask value has not been applied. If eoi_type is 0, this may indicate that an optimization determined by the application has been used. For example, optimization properties according to eoi_type may be defined as in Table 2 below.

[0102] ValueInterpretationeoi_type = = 0May be used as determined by the applicationeoi_type > 0 &&( eoi_type & 0x01 ) = = 0No object-based optimization( eoi_type & 0x01 ) != 0With object-based optimizationeoi_type > 0 &&( eoi_type & 0x02 ) = = 0No temporal resampling optimization( eoi_type & 0x02 ) != 0With temporal resampling optimizationeoi_type > 0 &&( eoi_type & 0x04 ) = = 0No spatial resampling optimization( eoi_type & 0x04 ) != 0With spatial resampling optimizationeoi_type > 0 &&( eoi_type & 0x08 ) = = 0No temporal quality optimization( eoi_type & 0x08 ) != 0With temporal quality optimizationeoi_type > 0 &&( eoi_type & 0x10 ) = = 0No spatial quality optimization( eoi_type & 0x10 ) != 0With spatial quality optimization; the pictures for which this SEI message persists have been pre-processed or encoded to reduce unnecessary information or improve the quality of necessary information.(e.g to reduce the amount of noise and remove speckles at the picture-level)eoi_type > 0 &&( eoi_type & 0x20 ) == 0No optimization for personal information protection( eoi_type & 0x20 ) != 0With personal information protection optimization; the pictures for which this SEI message persists have been pre-processed or encoded to protect personal information. (eg removal or replacing of personal identifiable information, pseudonymization, anonymization).

[0103] The encoder optimization information regarding the purpose, properties, and scope of the aforementioned optimization can be applied equally to the embodiments described below. Encoder optimization information can be defined in the SEI message as shown in Table 3 below.

[0104] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)}}

[0105] The applied optimization properties can be derived based on the information in Table 1 or Table 2. For example, the spatial resampling flag (EoiSpatialResamplingFlag) can indicate whether spatial resampling optimization is applied. If the value of EoiSpatialResamplingFlag is 1, this may mean that spatial resampling is applied. If the value of EoiSpatialResamplingFlag is 0, this may mean that spatial resampling is not applied. In this way, the applied optimization properties can be identified based on eoi_type, and detailed information about the applied optimization properties can be additionally defined in the encoder optimization information. The value of EoiSpatialResamplingFlag can be derived as in the following mathematical expression 1 or 2.

[0106] [Mathematical Formula 1]

[0107] EoiSpatialResamplingFlag = ((eoi_type & 0x04 ) > 0 ) ? 1:0

[0108] [Equation 2]

[0109] if((eoi_type & 0x04 ) != 0)

[0110] EoiSpatialResamplingFlag= 1;

[0111] else

[0112] EoiSpatialResamplingFlag= 0;

[0113] The present disclosure relates to a method for defining details regarding spatial resampling optimization.

[0114] A spatial resampling type identifier (eoi_spatial_resampling_type_idc) may be generated based on the value of EoiSpatialResamplingFlag being 1. eoi_spatial_resampling_type_idc may be information for identifying the type of spatial resampling applied.

[0115] For example, eoi_spatial_resampling_type_idc can be defined as shown in Table 4 below.

[0116] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){eoi_spatial_resampling_type_idcu(3)}}}}

[0117] In Table 4, if the value of eoi_spatial_resampling_type_idc is 0, this may indicate that the type of spatial resampling is upsampling. If the value of eoi_spatial_resampling_type_idc is 1, this may indicate that the type of spatial resampling is downsampling. If the value of eoi_spatial_resampling_type_idc is 2, this may indicate that the type of spatial resampling is neural network (e.g., AI, SR)-based upsampling. If the value of eoi_spatial_resampling_type_idc is 3, this may indicate that the type of spatial resampling is neural network-based downsampling. If the values ​​of eoi_spatial_resampling_type_idc are 0 and 1, this may indicate that it is not a neural network-based resampling method. Here, oversampling and downsampling are examples of spatial resampling, and other resampling methods can also be identified by eoi_spatial_resampling_type_idc.

[0118] eoi_spatial_resampling_type_idc can be encoded as a descriptor of u(3). That is, eoi_spatial_resampling_type_idc can be encoded as an unsigned integer with 3 bits. eoi_spatial_resampling_type_idc according to Table 4 can be expressed as 3 bits as shown in Table 5 below.

[0119] eoi_spatial_resampling_type_idcdescription000Up-sampling001Down-sampling010NN-based up-sampling011NN-based down-sampling100unknown101~111reserved for future use

[0120] For example, eoi_spatial_resampling_type_idc may be defined as shown in Table 6 below.

[0121] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){eoi_spatial_resampling_type_idcu(3)eoi_nn_based_resampling_flagu(1)}}}}

[0122] In Table 6, if the value of eoi_spatial_resampling_type_idc is 0, this may indicate that the type of spatial resampling is upsampling. If the value of eoi_spatial_resampling_type_idc is 1, this may indicate that the type of spatial resampling is downsampling. In this case, as shown in Table 5, based on the value of EoiSpatialResamplingFlag being 1, a neural network resampling flag (eoi_nn_based_resampling_flag) may be additionally generated.

[0123] If the value of eoi_nn_based_resampling_flag is 1, it may indicate that spatial resampling is neural network-based. If the value of eoi_nn_based_resampling_flag is 0, it may indicate that spatial resampling is not neural network-based.

[0124] eoi_nn_based_resampling_flag can be encoded after eoi_spatial_resampling_type_idc is encoded.

[0125] eoi_nn_based_resampling_flag can be encoded as a descriptor of u(1). That is, eoi_nn_based_resampling_flag can be encoded as an unsigned integer with 1 bit. eoi_spatial_resampling_type_idc can be encoded as a descriptor of u(3). That is, eoi_spatial_resampling_type_idc can be encoded as an unsigned integer with 3 bits. eoi_spatial_resampling_type_idc according to Table 6 can be expressed as 3 bits as shown in Table 7 below.

[0126] eoi_spatial_resampling_type_idcdescription000Up-sampling001Down-sampling011unknown100~111reserved for future use

[0127] As described in Table 5 or 7, if the type of spatial resampling according to eoi_spatial_resampling_type_idc is unknown, this may indicate that the type of spatial resampling is unclear. For example, if the width of a picture is upsampled and the height of the picture is downsampled, there may be no change in the overall size of the picture. In this case, the properties of spatial resampling can be known through the size information of the original picture. In order to enable the decoded picture to be restored at the original source resolution, it may be necessary to provide the size of the original picture to the receiving end, such as the decoding device.

[0128] The size information of the original picture according to the present disclosure may be defined as eoi_original_width and eoi_original_height. Here, eoi_original_width may be information indicating the width of the input picture (i.e., the original picture) before spatial resampling is applied. eoi_original_height may be information indicating the height of the input picture (i.e., the original picture) before spatial resampling is applied.

[0129] For example, the size information of the original picture can be defined as in Table 8 below.

[0130] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){eoi_spatial_resampling_type_idcu(3)original_pic_info_present_flagif(original_pic_infor_present_flag) {eoi_original_widthue(v)eoi_original_heightue(v)}}}}

[0131] According to Table 8, based on the value of EoiSpatialResamplingFlag being 1, eoi_spatial_resampling_type_idc and original_pic_info_present_flag can be generated, respectively.

[0132] eoi_spatial_resampling_type_idc is the same as previously discussed, so we will omit any duplicate explanation here.

[0133] original_pic_info_present_flag may be a flag indicating whether information related to the input picture (i.e., the original picture) before spatial resampling is applied exists. If the value of original_pic_info_present_flag is 1, this may mean that information related to the original picture exists. If the value of original_pic_info_present_flag is 0, this may mean that information related to the original picture does not exist. Here, the information related to the original picture may include information about the size of the original picture.

[0134] Based on the value of original_pic_info_present_flag being 1, eoi_original_width and eoi_original_height, which are the size information of the original picture, can be generated respectively. On the other hand, based on the value of original_pic_info_present_flag being 0, eoi_original_width and eoi_original_height may not be generated.

[0135] For example, the size information of the original picture may be defined as in Table 9 below.

[0136] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){original_pic_info_present_flagif(original_pic_infor_present_flag) {eoi_original_widthue(v)eoi_original_height(v)}else{eoi_spatial_resampling_type_idcu(3)}}}}

[0137] The bitstream may include information about the size of the encoded video picture. For example, the sequence parameter set (SPS) may include information indicating the width of the encoded video picture (sps_pic_width_max_in_luma_samples) and information indicating the height of the encoded video picture (sps_pic_height_max_in_luma_samples).

[0138] The type of spatial resampling can also be identified by comparing the size information of the encoded video picture with the size information of the original picture. For example, if the size indicated by eoi_original_width is larger than the size indicated by sps_pic_width_max_in_luma_samples, it can be inferred that the applied spatial resampling is upsampling. Conversely, if the size indicated by eoi_original_width is smaller than the size indicated by sps_pic_width_max_in_luma_samples, it can be inferred that the applied spatial resampling is downsampling. Similarly, the type of spatial resampling can be identified by comparing the sizes of eoi_original_height and sps_pic_height_max_in_luma_samples.

[0139] Therefore, as defined in Table 9, based on the value of original_pic_info_present_flag being 1, the size information (eoi_original_width, eoi_original_height) of the original picture is generated, but eoi_spatial_resampling_type_idc may not be generated. That is, based on the value of original_pic_info_present_flag being 1, the size information of the original picture may be encoded in the bitstream. Based on the value of original_pic_info_present_flag being 1, eoi_spatial_resampling_type_idc may not be encoded in the bitstream.

[0140] On the other hand, eoi_spatial_resampling_type_idc can be generated based on the value of original_pic_info_present_flag being 0. That is, eoi_spatial_resampling_type_idc can be encoded into the bitstream based on the value of original_pic_info_present_flag being 0. In this way, eoi_spatial_resampling_type_idc can be encoded into the bitstream when the size information of the original picture does not exist, because eoi_spatial_resampling_type_idc is unnecessary when the size information of the original picture is available.

[0141] eoi_spatial_resampling_type_idc can be encoded as a descriptor of u(3). That is, eoi_spatial_resampling_type_idc can be encoded as an unsigned integer with 3 bits. Here, original_pic_info_present_flag can be generated based on the value of EoiSpatialResamplingFlag being 1.

[0142] For example, eoi_spatial_resampling_type_idc may be defined as shown in Table 10 below.

[0143] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){eoi_spatial_resampling_type_idcu(2)}}}}

[0144] In Table 10, if the value of eoi_spatial_resampling_type_idc is 0, this may indicate that the type of spatial resampling is upsampling. If the value of eoi_spatial_resampling_type_idc is 1, this may indicate that the type of spatial resampling is downsampling. If the value of eoi_spatial_resampling_type_idc is 2, this may indicate that the type of spatial resampling is neural network (e.g., AI, SR)-based upsampling. If the value of eoi_spatial_resampling_type_idc is 3, this may indicate that the type of spatial resampling is neural network-based downsampling. If the values ​​of eoi_spatial_resampling_type_idc are 0 and 1, this may mean that it is not a neural network-based resampling method. Here, oversampling and downsampling are examples of spatial resampling, and other resampling methods can also be identified by eoi_spatial_resampling_type_idc.

[0145] eoi_spatial_resampling_type_idc can be encoded as a descriptor of u(2). That is, eoi_spatial_resampling_type_idc can be encoded as an unsigned integer with 2 bits. eoi_spatial_resampling_type_idc according to Table 10 can be expressed as 2 bits as shown in Table 11 below.

[0146] eoi_spatial_resampling_type_idcdescription00Up-sampling01Down-sampling10NN-based up-sampling011NN-based down-sampling

[0147] For example, eoi_spatial_resampling_type_idc may be defined as shown in Table 12 below.

[0148] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){eoi_nn_based_resampling_flagu(1)eoi_spatial_resampling_type_idcu(2)}}}}

[0149] In Table 12, if the value of eoi_spatial_resampling_type_idc is 0, this may indicate that the type of spatial resampling is upsampling. If the value of eoi_spatial_resampling_type_idc is 1, this may indicate that the type of spatial resampling is downsampling. In this case, as shown in Table 12, based on the value of EoiSpatialResamplingFlag being 1, a neural network resampling flag (eoi_nn_based_resampling_flag) may be additionally generated.

[0150] If the value of eoi_nn_based_resampling_flag is 1, it may indicate that spatial resampling is neural network-based. If the value of eoi_nn_based_resampling_flag is 0, it may indicate that spatial resampling is not neural network-based.

[0151] eoi_nn_based_resampling_flag can be encoded before eoi_spatial_resampling_type_idc is encoded.

[0152] eoi_nn_based_resampling_flag can be encoded as a descriptor of u(1). That is, eoi_nn_based_resampling_flag can be encoded as an unsigned integer with 1 bit. eoi_spatial_resampling_type_idc can be encoded as a descriptor of u(2). That is, eoi_spatial_resampling_type_idc can be encoded as an unsigned integer with 2 bits. eoi_spatial_resampling_type_idc according to Table 12 can be expressed as 2 bits as shown in Table 13 below.

[0153] eoi_spatial_resampling_type_idcdescription00Up-sampling01Down-sampling10unknown11reserved for future use

[0154] As described in Table 13, if the spatial resampling type according to eoi_spatial_resampling_type_idc is unknown, this may indicate that the type of spatial resampling is unclear. For example, if the width of a picture is upsampled and the height is downsampled, the overall size of the picture may not change. In this case, the properties of spatial resampling can be determined through the size information of the original picture.

[0155] The size information of the original picture according to the present disclosure may be defined as eoi_original_width and eoi_original_height. Here, eoi_original_width may be information indicating the width of the input picture (i.e., the original picture) before spatial resampling is applied. eoi_original_height may be information indicating the height of the input picture (i.e., the original picture) before spatial resampling is applied.

[0156] For example, the size information of the original picture can be defined as in Table 14 below.

[0157] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){eoi_spatial_resampling_type_idcu(2)original_pic_info_present_flagif(original_pic_infor_present_flag) {eoi_original_widthue(v)eoi_original_heightue(v)}}}}

[0158] According to Table 14, based on the value of EoiSpatialResamplingFlag being 1, eoi_spatial_resampling_type_idc and original_pic_info_present_flag can be generated respectively.

[0159] eoi_spatial_resampling_type_idc is the same as previously discussed, so we will omit any duplicate explanation here.

[0160] original_pic_info_present_flag may be a flag indicating whether information related to the input picture (i.e., the original picture) before spatial resampling is applied exists. If the value of original_pic_info_present_flag is 1, this may mean that information related to the original picture exists. If the value of original_pic_info_present_flag is 0, this may mean that information related to the original picture does not exist. Here, the information related to the original picture may include information about the size of the original picture.

[0161] Based on the value of original_pic_info_present_flag being 1, the size information of the original picture, eoi_original_width and eoi_original_height, can be generated respectively. On the other hand, based on the value of original_pic_info_present_flag being 0, the size information of the original picture, eoi_original_width and eoi_original_height, may not be generated.

[0162] For example, the size information of the original picture may be defined as in Table 15 below.

[0163] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){original_pic_info_present_flagif(original_pic_infor_present_flag) {eoi_original_widthue(v)eoi_original_height(v)}else{eoi_spatial_resampling_type_idcu(2)}}}}

[0164] The bitstream may include information about the size of the encoded video picture. For example, the sequence parameter set (SPS) may include information indicating the width of the encoded video picture (sps_pic_width_max_in_luma_samples) and information indicating the height of the encoded video picture (sps_pic_height_max_in_luma_samples).

[0165] The type of spatial resampling can also be identified by comparing the size information of the encoded video picture with the size information of the original picture. For example, if the size indicated by eoi_original_width is larger than the size indicated by sps_pic_width_max_in_luma_samples, it can be inferred that the applied spatial resampling is upsampling. Conversely, if the size indicated by eoi_original_width is smaller than the size indicated by sps_pic_width_max_in_luma_samples, it can be inferred that the applied spatial resampling is downsampling. Similarly, the type of spatial resampling can be identified by comparing the sizes of eoi_original_height and sps_pic_height_max_in_luma_samples.

[0166] Therefore, as defined in Table 15, the size information (eoi_original_width, eoi_original_height) of the original picture is generated based on the value of original_pic_info_present_flag being 1, but eoi_spatial_resampling_type_idc may not be generated. That is, based on the value of original_pic_info_present_flag being 1, the size information of the original picture may be encoded in the bitstream. Based on the value of original_pic_info_present_flag being 1, eoi_spatial_resampling_type_idc may not be encoded in the bitstream.

[0167] On the other hand, based on the value of original_pic_info_present_flag being 0, eoi_spatial_resampling_type_idc can be generated. That is, based on the value of original_pic_info_present_flag being 0, eoi_spatial_resampling_type_idc can be encoded in the bitstream. Here, eoi_spatial_resampling_type_idc can be encoded as a descriptor of u(2). That is, eoi_spatial_resampling_type_idc can be encoded as an unsigned integer with 2 bits. Here, original_pic_info_present_flag can be generated based on the value of EoiSpatialResamplingFlag being 1.

[0168] The present disclosure relates to a method for defining details regarding spatial resampling optimization.

[0169] Based on the value of the aforementioned EoiSpatialResamplingFlag being 1, detailed information regarding spatial resampling optimization can be generated. Here, the detailed information regarding spatial resampling optimization can include at least one of an upsampling flag (eoi_upsampling_flag), a downsampling flag (eoi_downsampling_flag), a neural network-based upsampling flag (eoi_nn_based_upsampling_flag), a neural network-based downsampling flag (eoi_nn_based_downsampling_flag), or a neural network-based resampling flag (eoi_nn_based_resampling_flag).

[0170] If the value of eoi_upsampling_flag is 1, this may indicate that the applied spatial resampling is upsampling. If the value of eoi_upsampling_flag is 0, this may indicate that the applied spatial resampling is not upsampling.

[0171] If the value of eoi_downsampling_flag is 1, this may indicate that the applied spatial resampling is downsampling. If the value of eoi_downsampling_flag is 0, this may indicate that the applied spatial resampling is not downsampling.

[0172] If the value of eoi_nn_based_upsampling_flag is 1, this may indicate that the applied spatial resampling is neural network-based upsampling. If the value of eoi_nn_based_upsampling_flag is 0, this may indicate that the applied spatial resampling is not neural network-based upsampling.

[0173] If the value of eoi_nn_based_downsampling_flag is 1, this may indicate that the applied spatial resampling is neural network-based downsampling. If the value of eoi_nn_based_downsampling_flag is 0, this may indicate that the applied spatial resampling is not neural network-based downsampling.

[0174] If the value of eoi_nn_based_resampling_flag is 1, this may indicate that the applied spatial resampling is neural network-based. If the value of eoi_nn_based_resampling_flag is 0, this may indicate that the applied spatial resampling is not neural network-based.

[0175] For example, details about spatial resampling optimization can include eoi_upsampling_flag, eoi_downsampling_flag, and eoi_nn_based_resampling_flag, and can be defined in the encoder optimization information as shown in Table 16 below.

[0176] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){eoi_upsampling_flagu(1)eoi_downsampling_flagu(1)eoi_nn_based_resampling_flagu(1)}}}

[0177] In Table 16, if the value of eoi_upsampling_flag is 1 and the value of eoi_nn_based_resampling_flag is 1, this may mean that neural network-based upsampling is applied. If the value of eoi_upsampling_flag is 1 and the value of eoi_nn_based_resampling_flag is 0, this may mean that upsampling other than neural network-based upsampling is applied.

[0178] eoi_upsampling_flag and eoi_downsampling_flag may be constrained to not have the same values. That is, eoi_upsampling_flag and eoi_downsampling_flag may not both be generated as 1 or 0. For example, if the value of eoi_upsampling_flag is 1, eoi_downsampling_flag cannot be 1. Conversely, if the value of eoi_upsampling_flag is 0, eoi_downsampling_flag cannot be 0.

[0179] Alternatively, details regarding spatial resampling optimization may include eoi_upsampling_flag, eoi_downsampling_flag, eoi_nn_based_upsampling_flag, and eoi_nn_based_downsampling_flag, and may be defined in the encoder optimization information as shown in Table 17 below.

[0180] encoder_optimization_info(payloadSize) {Descriptor eoi_cancel_flagu(1) if(!eoi_cancel_flag){ eoi_persistence_flagu(1) eoi_for_human_viewing_idcu(2) eoi_for_machine_analysis_idcu(2) eoi_typeu(16)if(EoiSpatialResamplingFlag){eoi_upsampling_flagu(1)eoi_downsampling_flagu(1)eoi_nn_based_upsampling_flagu(1)eoi_nn_based_downsampling_flagu(1)}}}

[0181] A bitstream including the compressed video picture and the encoder optimization information can be generated (S430). The encoder optimization information can be configured in an SEI message of the bitstream. The SEI message can be included in a NAL (network abstraction layer) unit of the bitstream.

[0182] FIG. 5 illustrates a schematic configuration of an encoding device (200) that performs a method for generating a bitstream according to the present disclosure.

[0183] Referring to FIG. 5, the encoding device (200) may include a receiving unit (500), a video compression unit (510), an EOI generation unit (520), and a bitstream generation unit (530).

[0184] The receiving unit (500) can receive one or more video pictures to be encoded.

[0185] The video compression unit (510) can encode one or more received video pictures to generate compressed video pictures.

[0186] The EOI generation unit (520) can generate encoder optimization information.

[0187] The bitstream generation unit (530) can generate a bitstream including a compressed video picture and encoder optimization information.

[0188] FIG. 6 illustrates a method for restoring a video picture performed in a decoding device (300) according to the present disclosure.

[0189] A bitstream including an encoded video picture can be received (S600).

[0190] The encoded video picture of the bitstream can be restored (S610).

[0191] Video information about an encoded video picture can be extracted from a bitstream. The encoded video picture can be restored based on the extracted video information.

[0192] Additionally, the NAL unit of the bitstream may include an SEI message. The SEI message may define encoder optimization information (EOI). The encoder optimization information may be related to the encoded video picture. The encoder optimization information may be included in the SEI message and signaled through the bitstream.

[0193] The above encoder optimization information may include an EOI cancellation flag (eoi_cancel_flag). Based on eoi_cancel_flag being 0, optimization-related information may be included in the encoder optimization information, as discussed with reference to FIG. 4.

[0194] Additionally, details about spatial resampling optimization can be included in the encoder optimization information based on the spatial resampling flag (EoiSpatialResamplingFlag) that indicates whether spatial resampling optimization is applied.

[0195] The method for deriving the value of EoiSpatialResamplingFlag is as described with reference to Fig. 4. Based on the value of EoiSpatialResamplingFlag being 1, detailed information regarding spatial resampling optimization can be included in the encoder optimization information. This is as described with reference to Fig. 4, and a detailed description thereof will be omitted here.

[0196] For example, based on the value of EoiSpatialResamplingFlag being 1, a spatial resampling type identifier (eoi_spatial_resampling_type_idc) may be included in the encoder optimization information. Here, eoi_spatial_resampling_type_idc may be encoded as an unsigned integer with 3 bits. Alternatively, eoi_spatial_resampling_type_idc may be encoded as an unsigned integer with 2 bits.

[0197] For example, based on the value of EoiSpatialResamplingFlag being 1, the spatial resampling type identifier (eoi_spatial_resampling_type_idc) and the neural network resampling flag (eoi_nn_based_resampling_flag) may be included in the encoder optimization information.

[0198] Here, eoi_nn_based_resampling_flag may be encoded after eoi_spatial_resampling_type_idc is encoded. Alternatively, eoi_nn_based_resampling_flag may be encoded before eoi_spatial_resampling_type_idc is encoded. eoi_nn_based_resampling_flag may be encoded as an unsigned integer with 1 bit. eoi_spatial_resampling_type_idc may be encoded as an unsigned integer with 3 bits. Alternatively, eoi_spatial_resampling_type_idc may be encoded as an unsigned integer with 2 bits.

[0199] For example, based on the value of EoiSpatialResamplingFlag being 1, the aforementioned eoi_spatial_resampling_type_idc and original_pic_info_present_flag may each be included in the encoder optimization information. Based on the value of original_pic_info_present_flag being 1, eoi_original_width and eoi_original_height, which are the size information of the original picture, may each be included in the encoder optimization information. On the other hand, based on the value of original_pic_info_present_flag being 0, eoi_original_width and eoi_original_height may not be included in the encoder optimization information.

[0200] For example, based on the value of original_pic_info_present_flag being 1, the size information of the original picture (eoi_original_width, eoi_original_height) may be included in the encoder optimization information, but eoi_spatial_resampling_type_idc may not be included in the encoder optimization information. Based on the value of original_pic_info_present_flag being 1, the size information of the original picture may be extracted from the bitstream.

[0201] On the other hand, based on the value of original_pic_info_present_flag being 0, eoi_spatial_resampling_type_idc may be included in the encoder optimization information. Based on the value of original_pic_info_present_flag being 0, eoi_spatial_resampling_type_idc may be extracted from the bitstream. Here, original_pic_info_present_flag may be encoded based on the value of EoiSpatialResamplingFlag being 1. original_pic_info_present_flag may be extracted from the bitstream based on the value of EoiSpatialResamplingFlag being 1.

[0202] For example, based on the value of EoiSpatialResamplingFlag being 1, details regarding spatial resampling optimization may be included in the encoder optimization information, as discussed with reference to FIG. 4.

[0203] FIG. 7 illustrates a schematic configuration of a decoding device (300) that performs a method for restoring a video picture according to the present disclosure.

[0204] Referring to FIG. 7, the decoding device (300) may include a receiving unit (700), a video information extraction unit (710), and a video restoration unit (720).

[0205] The receiving unit (700) can receive a bitstream including an encoded video picture.

[0206] The video information extraction unit (710) can extract video information about an encoded video picture from a bitstream. In addition, the video information extraction unit (710) can extract an SEI message from a NAL unit of the bitstream. The extracted SEI message can include encoder optimization information.

[0207] The video restoration unit (720) can restore an encoded video picture based on the extracted video information.

[0208] In the embodiments described above, the methods are described based on a flowchart as a series of steps or blocks. However, the embodiments are not limited to the order of the steps, and some steps may occur in a different order or simultaneously with other steps described above. Furthermore, those skilled in the art will understand that the steps depicted in the flowchart are not exclusive, and other steps may be included, or one or more steps in the flowchart may be deleted without affecting the scope of the embodiments of this document.

[0209] The method according to the embodiments of the present document described above can be implemented in the form of software, and the encoding device and / or decoding device according to the present document can be included in a device that performs image processing, such as a TV, a computer, a smartphone, a set-top box, a display device, etc.

[0210] When the embodiments in this document are implemented as software, the above-described method can be implemented as a module (process, function, etc.) that performs the above-described function. The module can be stored in memory and executed by a processor. The memory can be internal or external to the processor and can be connected to the processor by various well-known means. The processor can include an application-specific integrated circuit (ASIC), another chipset, logic circuit, and / or data processing device. The memory can include a read-only memory (ROM), a random access memory (RAM), flash memory, a memory card, a storage medium, and / or other storage devices. That is, the embodiments described in this document can be implemented and performed on a processor, a microprocessor, a controller, or a chip. For example, the functional units illustrated in each drawing can be implemented and performed on a computer, a processor, a microprocessor, a controller, or a chip. In this case, information for implementation (e.g., information on instructions) or an algorithm can be stored on a digital storage medium.

[0211] In addition, the decoding device and encoding device to which the embodiment(s) of the present specification are applied may be included in a multimedia broadcasting transmitting and receiving device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video conversation device, a real-time communication device such as a video communication, a mobile streaming device, a storage medium, a camcorder, a video-on-demand (VoD) service providing device, an OTT (Over the top video) device, an Internet streaming service providing device, a three-dimensional (3D) video device, a VR (virtual reality) device, an AR (argumente reality) device, a video phone video device, a transportation terminal (ex. a vehicle (including an autonomous vehicle) terminal, an airplane terminal, a ship terminal, etc.), and a medical video device, and may be used to process a video signal or a data signal. For example, the OTT (Over the top video) device may include a game console, a Blu-ray player, an Internet-connected TV, a home theater system, a smartphone, a tablet PC, a DVR (Digital Video Recorder), etc.

[0212] In addition, the processing method to which the embodiment(s) of the present specification are applied can be produced in the form of a computer-executable program and can be stored in a computer-readable recording medium. Multimedia data having a data structure according to the embodiment(s) of the present specification can also be stored in a computer-readable recording medium. The computer-readable recording medium includes all types of storage devices and distributed storage devices in which computer-readable data is stored. The computer-readable recording medium can include, for example, a Blu-ray disc (BD), a universal serial bus (USB), a ROM, a PROM, an EPROM, an EEPROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device. In addition, the computer-readable recording medium includes a medium implemented in the form of a carrier wave (e.g., transmission via the Internet). In addition, a bitstream generated by an encoding method can be stored in a computer-readable recording medium or transmitted via a wired or wireless communication network.

[0213] Additionally, the embodiments of the present disclosure may be implemented as a computer program product by program code, and the program code may be executed on a computer by the embodiments of the present disclosure. The program code may be stored on a computer-readable carrier.

[0214] FIG. 8 illustrates an example of a content streaming system to which embodiments of the present disclosure can be applied.

[0215] Referring to FIG. 8, a content streaming system to which the embodiment(s) of the present specification are applied may largely include an encoding server, a streaming server, a web server, a media storage, a user device, and a multimedia input device.

[0216] The encoding server compresses content input from multimedia input devices such as smartphones, cameras, and camcorders into digital data, generates a bitstream, and transmits it to the streaming server. Alternatively, if multimedia input devices such as smartphones, cameras, and camcorders directly generate bitstreams, the encoding server may be omitted.

[0217] The above bitstream can be generated by an encoding method or a bitstream generation method to which the embodiment(s) of the present specification are applied, and the streaming server can temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0218] The streaming server transmits multimedia data to a user device based on a user request via a web server, and the web server acts as an intermediary to inform the user of available services. When a user requests a desired service from the web server, the web server transmits the request to the streaming server, and the streaming server transmits the multimedia data to the user. At this time, the content streaming system may include a separate control server, in which case the control server controls commands / responses between each device within the content streaming system.

[0219] The streaming server can receive content from a media repository and / or an encoding server. For example, when receiving content from the encoding server, the content can be received in real time. In this case, to provide a smooth streaming service, the streaming server can store the bitstream for a certain period of time.

[0220] Examples of the user devices may include mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glasses, HMDs), digital TVs, desktop computers, digital signage, etc.

[0221] Each server within the above content streaming system can be operated as a distributed server, in which case data received from each server can be processed in a distributed manner.

[0222] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined and implemented as a device, and the technical features of the device claims of this specification may be combined and implemented as a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a method.

Claims

1. A step of receiving a video picture to be encoded; A step of encoding the received video picture to generate a compressed video picture; a step of generating encoder optimization information; and A step of generating a bitstream including the compressed video picture and the encoder optimization information, The above encoder optimization information includes the size information of the original picture, A method in which the size information of the original picture is generated based on a flag indicating whether information related to the original picture exists.

2. In paragraph 1, A method wherein the size information of the original picture includes information indicating the width of the original picture and information indicating the height of the original picture.

3. In paragraph 2, If the value of the above flag is 1, information related to the original picture exists, A method in which, if the value of the above flag is 0, there is no information related to the original picture.

4. In paragraph 3, A method in which information indicating the width of the original picture and information indicating the height of the original picture are each generated based on the value of the flag being 1.

5. In paragraph 3, A method in which information indicating the width of the original picture and information indicating the height of the original picture are not generated based on the value of the flag being 0.

6. In paragraph 5, A method wherein a spatial resampling type identifier is generated to identify the type of spatial resampling applied based on the value of the above flag being 0.

7. In paragraph 1, The above flag is generated based on a spatial resampling flag indicating whether spatial resampling optimization has been applied.

8. In paragraph 7, The above spatial resampling flag is derived based on EOI type information regarding the properties of the optimization method.

9. A step of receiving a bitstream including an encoded video picture; and A step of restoring an encoded video picture included in the above bitstream, The above bitstream contains encoder optimization information, The above encoder optimization information includes the size information of the original picture, A method in which the size information of the original picture is included based on a flag indicating whether information related to the original picture exists.

10. A computer-readable storage medium storing a bitstream generated by the method according to paragraph 1.

11. A step of generating a bitstream; wherein the bitstream is generated based on the steps of: receiving a video picture to be encoded; encoding the received video picture to generate a compressed video picture; generating encoder optimization information; and generating a bitstream including the compressed video picture and the encoder optimization information. Including a step of transmitting data including the above bitstream, The above encoder optimization information includes the size information of the original picture, A method in which the size information of the original picture is generated based on a flag indicating whether information related to the original picture exists.

Images