Image encoding / decoding method and device, and recording medium on which bitstream is stored

Abstract

An image decoding method and device according to the present disclosure may receive a bitstream including an encoded video picture and reconstruct the encoded video picture included in the bitstream. Here, the bitstream may be configured to include a source picture timing information (SPTI) supplemental enhancement information (SEI) message. The SPTI SEI message may include source type information indicating a timing relationship between source pictures and decoded output pictures.

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 within 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 an SEI message regarding source picture timing information.

[0005] The present disclosure provides a method and apparatus for signaling an SEI message regarding source picture timing information.

[0006] A video decoding method and device according to the present disclosure can receive a bitstream including an encoded video picture, and reconstruct the encoded video picture included in the bitstream. The bitstream can be configured to include a source picture timing information (SPTI) supplemental enhancement information (SEI) message. The SPTI SEI message can include source type information, and the source type information can indicate a timing relationship between source pictures and decoded output pictures corresponding to the source pictures. The SPTI SEI message can be obtained from a network abstraction layer (NAL) unit of the bitstream.

[0007] In the video decoding method and device according to the present disclosure, the source type information may specify at least one of a plurality of pre-defined timing relationships. The plurality of timing relationships may include at least one of slow motion, sped-up motion, high-speed imaging, time-lapse imaging, time reversal, still image, or single-shot timing.

[0008] In the video decoding method and device according to the present disclosure, the source type information may be limited so as not to simultaneously display the slow motion and the sped-up motion.

[0009] In the image decoding method and device according to the present disclosure, the source type information may be limited so as not to simultaneously display the high-speed imaging and the time-lapse imaging.

[0010] In the image decoding method and device according to the present disclosure, the source type information may be restricted so as not to simultaneously represent the still image and at least one other timing relationship belonging to the plurality of timing relationships.

[0011] In the video decoding method and device according to the present disclosure, the SPTI SEI message may further include a slow motion flag. The slow motion flag may indicate whether the timing relationship between the source pictures and the decoded output pictures is slow motion.

[0012] In the image decoding method and device according to the present disclosure, the SPTI SEI message may further include a high-speed imaging flag. The high-speed imaging flag may indicate whether the timing relationship between the source pictures and the decoded output pictures is high-speed imaging.

[0013] In the video decoding method and device according to the present disclosure, the SPTI SEI message may further include time unit count information. The time unit count information may indicate the number of time units of a clock operating at a predetermined frequency.

[0014] In the video decoding method and device according to the present disclosure, the time unit number information may be signaled based on a source picture interval flag. Here, the source picture interval flag having a value of 1 may indicate that both the basic source picture interval and the source picture interval are 0, and the source picture interval flag having a value of 0 may indicate that information indicating the basic source picture interval and the source picture interval follows.

[0015] In the video decoding method and device according to the present disclosure, the time unit number information may be allowed to have a value of 0.

[0016] A video encoding method and device according to the present disclosure may receive a video picture to be encoded, encode the received video picture to generate video information about the video picture, generate a source picture timing information (SPTI) supplemental enhancement information (SEI) message, and generate a bitstream including the video information and the SPTI SEI message. The SPTI SEI message may include source type information, and the source type information may indicate a timing relationship between source pictures and decoded output pictures corresponding to the source pictures. The SPTI SEI message may be encoded in a network abstraction layer (NAL) unit of the bitstream.

[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, a bitmask for timing relations can be allocated more efficiently by limiting the cases where timing relations with conflicting properties appear simultaneously.

[0021] According to the present disclosure, by clearly specifying the value of source picture timing information, confusion arising during the implementation process can be suppressed or the use of unnecessary resources can be reduced.

[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 restoring a video picture performed in a decoding device (300) according to the present disclosure.

[0026] FIG. 5 illustrates a schematic configuration of a decoding device (300) that performs a method for restoring a video picture according to the present disclosure.

[0027] FIG. 6 illustrates a method for generating a bitstream performed in an encoding device (200) according to the present disclosure.

[0028] FIG. 7 illustrates a schematic configuration of an encoding device (200) that performs a method for generating a bitstream 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. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[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 of 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 through 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 restoring a video picture performed in a decoding device (300) according to the present disclosure.

[0090] A bitstream including an encoded video picture can be received (S400).

[0091] The encoded video picture of the bitstream can be restored (S410).

[0092] 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.

[0093] The bitstream may be configured to include source picture timing information (SPTI) supplemental enhancement information (SEI) messages.

[0094] The SPTI SEI message may indicate the temporal distance between the source pictures associated with the corresponding decoded output pictures before encoding. For example, for content captured by a camera, the temporal distance between the source pictures may be the difference between the time an image sensor was exposed to generate the source picture associated with the currently decoded picture and the time an image sensor was exposed to generate the source picture associated with the previously decoded picture in output order. The information provided by the SPTI SEI message may be applied to all subsequent pictures in the current layer in output order, starting from the picture in the current layer of the access unit (AU) containing the SPTI SEI message.

[0095] For example, the SPTI SEI message can be defined as shown in Table 1 below.

[0096] source_picture_timing_info( payloadSize ) {Descriptorspti_cancel_flagu(1)if( !spti_cancel_flag ) {spti_persistence_flagu(1)spti_source_timing_equals_output_timing_flagu(1)if( !spti_source_timing_equals_output_timing_flag ) {spti_source_type_present_flagu(1)if( spti_source_type_present_flag )spti_source_typeu(16)spti_time_scaleu(32)spti_num_units_in_elemental_intervalu(32)if( spti_persistence_flag )spti_max_sublayers_minus_1u(3)for( i = 0; i <= spti_max_sublayers_minus1; {spti_sublayer_interval_scale_factor[ i ]ue(v)spti_sublayer_synthesized_picture_flag[ i ]u(1)}}}}

[0097] An SPTI SEI message may include an SPTI cancel flag (spti_cancel_flag). If spti_cancel_flag is 1, this may indicate that the SPTI SEI message cancels the persistence of a previous SPTI SEI message in the output order applied to the current layer. If spti_cancel_flag is 0, this may indicate that source picture timing information follows.

[0098] The SPTI SEI message may include the SPTI persistence flag (spti_persistence_flag). spti_persistence_flag may specify the persistence of the SPTI SEI message for the current layer. If spti_persistence_flag is 0, this may indicate that the SPTI SEI message applies only to the currently decoded picture. If spti_persistence_flag is 1, this may indicate that the SPTI SEI message applies to the currently decoded picture and persists for all subsequent pictures of the current layer in output order.

[0099] The SPTI SEI message may include timing flag information (spti_source_timing_equals_output_timing_flag). If spti_source_timing_equals_output_timing_flag is 1, this may indicate that the timing of the source pictures is the same as the timing of the corresponding decoded output pictures. If spti_source_timing_equals_output_timing_flag is 0, this may indicate that the timing of the source pictures may not be the same as the timing of the corresponding decoded output pictures. If spti_source_timing_equals_output_timing_flag is 1 and a picture timing SEI message for the current picture exists, the source picture timing may be determined based on the information conveyed through the picture timing SEI message.

[0100] An SPTI SEI message may include a source type presence flag (spti_source_type_present_flag). If spti_source_type_present_flag is 1, this may indicate that source type information (spti_source_type) exists in the SEI message. If spti_source_type_present_flag is 0, this may indicate that source type information does not exist in the SEI message.

[0101] An SPTI SEI message may include source type information (spti_source_type). spti_source_type may indicate a timing relationship between source pictures and corresponding decoded output pictures. spti_source_type may specify at least one of a plurality of pre-defined timing relationships. The plurality of pre-defined timing relationships may include at least one of slow motion, sped-up motion, high-speed imaging, time-lapse imaging, temporal reversal, still image / freeze frame, or sporadic or event-driven timing. For example, spti_source_type may be defined as shown in Table 2.

[0102] bitMaskInterpretation0x01Slow motion: The absolute value of the temporal distance between consecutive source pictures is likely to be less than the temporal distance between corresponding decoded output pictures.0x02Sped-up motion: The absolute value of the temporal distance between consecutive source pictures is likely to be greater than the temporal distance between corresponding decoded output pictures.0x04High-speed imaging: The absolute value of the temporal distance between consecutive source pictures is likely to be less than 1 / 120 seconds.0x08Time-lapse imaging: The temporal distance between source pictures is likely to be greater than 1.001 / 24 seconds.0x10Temporal reversal: The absolute value of the temporal distance between consecutive source pictures is indicated to be negative (i.e., decoded pictures are output in reverse temporal order relative to the timing of the corresponding source pictures).0x20Still image / freeze frame: The temporal distance between source pictures is likely to be 0 (ie, two or more decoded pictures are likely to represent the same source picture).0x40Sporadic or event-driven: The temporal distance between source pictures is likely to be non-constant.

[0103] In Table 2, if (spti_source_type & bitMask) is not 0, this may indicate that the timing relationship has an interpretation corresponding to the bitMask value in Table 2. If spti_source_type is greater than 0 and (spti_source_type & bitMask) is 0, the interpretation corresponding to the bitMask value may not be applied to the SPTI SEI message. If spti_source_type is 0, the timing relationship may be specified by the application.

[0104] The value of spti_source_type may be constrained to fall in the range 0 to 127. The values ​​128 to 255 for spti_source_type are reserved for future use, and decoders of certain specifications must ignore SPTI SEI messages with spti_source_types in the range 128 to 255.

[0105] Currently, the SPTI SEI message allows spti_source_type to simultaneously indicate slow motion and sped-up motion. However, this is inconsistent and can lead to implementation confusion. Assigning bitmasks to timing relationships that are not used together can be inefficient.

[0106] To solve the above problem, the values ​​of ((spti_source_type & 0x01) & (spti_source_type & 0x02)) according to Table 2 can be restricted to be 0. That is, spti_source_type can be restricted to not exhibit slow motion and sped-up motion at the same time.

[0107] Additionally, the current SPTI SEI message allows spti_source_type to simultaneously indicate high-speed imaging and time-lapse imaging. However, this is inconsistent and can lead to implementation confusion. Assigning bitmasks to timing relationships that are not used together can be inefficient.

[0108] To address the aforementioned issue, the values ​​of ((spti_source_type & 0x04) & (spti_source_type & 0x08)) according to Table 2 can be constrained to be 0. That is, spti_source_type can be constrained to not represent high-speed imaging and time-lapse imaging simultaneously.

[0109] Alternatively, a single bit can be allocated for the timing relationship of conflicting attributes. For example, the SPTI SEI message can be defined as shown in Table 3 below.

[0110] source_picture_timing_info( payloadSize ) {Descriptorspti_cancel_flagu(1)if( !spti_cancel_flag ) {spti_persistence_flagu(1)spti_source_timing_equals_output_timing_flagu(1)if( !spti_source_timing_equals_output_timing_flag ) {spti_source_type_present_flagu(1)if( spti_source_type_present_flag ) {spti_source_typeu(16)if( SptiSlowSpedUpMotionFlag )spti_slow_motion_flagu(1)if( SptiHighSpeedTimeLapsImagingFlag )spti_high_speed_imaging_flagu(1)}spti_time_scaleu(32)spti_num_units_in_elemental_intervalu(32)if( spti_persistence_flag )spti_max_sublayers_minus_1u(3)for( i = 0; i <= spti_max_sublayers_minus1; i++ ) {spti_sublayer_interval_scale_factor[ i ]ue(v)spti_sublayer_synthesized_picture_flag[ i ]u(1)}}}}

[0111] According to Table 3, the SPTI SEI message may include a slow motion flag (spti_slow_motion_flag). spti_slow_motion_flag may indicate whether the timing relationship between the source picture and the corresponding decoded output picture is slow motion. For example, when spti_slow_motion_flag is 1, this may indicate that the timing relationship between the source picture and the corresponding decoded output picture is slow motion. When spti_slow_motion_flag is 0, this may indicate that the timing relationship between the source picture and the corresponding decoded output picture is slow-up motion.

[0112] spti_slow_motion_flag may be adaptively signaled based on a given flag (SptiSlowSpedUpMotionFlag). Here, SptiSlowSpedUpMotionFlag may specify whether spti_source_type indicates a timing relationship including slow motion and sped-up motion. SptiSlowSpedUpMotionFlag may be derived based on the value of spti_source_type, and may be derived, for example, as in the following mathematical expression 1.

[0113] [Mathematical Formula 1]

[0114] SptiSlowSpedUpMotionFlag = ( ( spti_source_type & 0x01 ) > 0 ) ? 1:0

[0115] According to Table 3, the SPTI SEI message may include a high-speed imaging flag (spti_high_speed_imaging_flag). spti_high_speed_imaging_flag may indicate whether the timing relationship between a source picture and its corresponding decoded output picture is high-speed imaging. For example, when spti_high_speed_imaging_flag is 1, this may indicate that the timing relationship between the source picture and its corresponding decoded output picture is high-speed imaging. When spti_high_speed_imaging_flag is 0, this may indicate that the timing relationship between the source picture and its corresponding decoded output picture is time-lapse imaging.

[0116] spti_high_speed_imaging_flag may be adaptively signaled based on a given flag (SptiHighSpeedTimeLapsImagingFlag). Here, SptiHighSpeedTimeLapsImagingFlag may specify whether spti_source_type indicates a timing relationship including high-speed imaging and time-lapse imaging. SptiHighSpeedTimeLapsImagingFlag may be derived based on the value of spti_source_type, and may be derived, for example, as in the following mathematical expression 2.

[0117] [Equation 2]

[0118] SptiHighSpeedTimeLapsImagingFlag = ( ( spti_source_type & 0x02 ) > 0 ) ? 1:0

[0119] Additionally, the current SPTI SEI message allows spti_source_type to simultaneously represent still image / freeze frame and other timing relationships. However, this is inconsistent and can cause implementation confusion. Assigning bitmasks to timing relationships that are not used together can be inefficient.

[0120] To address the aforementioned issue, the values ​​of ((spti_source_type & 0x20) & (spti_source_type & 0x5F)) according to Table 2 can be restricted to be 0. That is, spti_source_type can be restricted to exclusively represent still images.

[0121] If the value of (spti_source_type & 0x20) is greater than 0, spti_source_type may be restricted to represent only still images. spti_source_type may be restricted to not represent both still images and other timing relation(s) belonging to the pre-defined multiple timing relations. For example, even if the value of (spti_source_type & 0x01) is greater than 0, spti_source_type may be restricted to represent only still images and not slow motion if the value of (spti_source_type & 0x20) is greater than 0.

[0122] spti_source_type can be adaptively signaled based on spti_source_type_present_flag. For example, spti_source_type can be signaled based on spti_source_type_present_flag being 1. Spti_source_type can be not signaled based on spti_source_type_present_flag being 0.

[0123] The SPTI SEI message may include time scale information (spti_time_scale). spti_time_scale may specify the number of time units that elapse in one second. spti_time_scale may be constrained to not have a value of 0. For example, in a time coordinate system that measures time using a 27 MHz clock, spti_time_scale may be 27,000,000.

[0124] The SPTI SEI message may include time unit number information (spti_num_units_in_elemental_interval). spti_num_units_in_elemental_interval may specify the number of time units of a clock operating at a frequency of spti_time_scale Hz, which corresponds to the source picture interval of consecutive pictures in output order in a coded layer video sequence (CLVS). spti_num_units_in_elemental_interval may be restricted not to have a value of 0. The source picture interval in seconds, represented by the variable ElementalSourcePictureInterval, may be equal to the quotient of the value of spti_num_units_in_elemental_interval divided by the value of spti_time_scale. For example, to represent a source picture interval of 0.04 seconds, the value of spti_time_scale could be equal to 27,000,000, and the value of spti_num_units_in_elemental_interval could be equal to 1,080,000.

[0125] If spti_num_units_in_elemental_interval is restricted to not have a value of 0, it may not be possible to represent the source picture interval of a still image.

[0126] To address this issue, an additional flag indicating that the source picture interval is 0 can be defined. For example, the SPTI SEI message can be defined as shown in Table 4 below.

[0127] source_picture_timing_info( payloadSize ) {Descriptorspti_cancel_flagu(1)if( !spti_cancel_flag ) {spti_persistence_flagu(1)spti_source_timing_equals_output_timing_flagu(1)if( !spti_source_timing_equals_output_timing_flag ) {spti_source_picture_interval_equals_to_zero_flagu(1)if( !spti_source_picture_interval_equal_to_zero_flag ) {spti_source_type_present_flagu(1)if( spti_source_type_present_flag )spti_source_typeu(16)spti_time_scaleu(32)spti_num_units_in_elemental_intervalu(32)if( spti_persistence_flag )spti_max_sublayers_minus_1u(3)for( i = 0; i <= spti_max_sublayers_minus1; i++ ) {spti_sublayer_interval_scale_factor[ i ]ue(v)spti_sublayer_synthesized_picture_flag[ i ]u(1)}}}}}

[0128] According to Table 4, the SPTI SEI message may include a source picture interval flag (spti_source_picture_interval_equals_to_zero_flag). When spti_source_picture_interval_equals_to_zero_flag is 1, this may indicate that the elementary source picture intervals of consecutive pictures in output order in the CLVS are 0, and the source picture intervals of corresponding pictures in the CLVS whose TemporalId is i are 0. When spti_source_picture_interval_equals_to_zero_flag is 0, this may indicate that the elementary source picture interval and information indicating the source picture interval follow. That is, based on spti_source_picture_interval_equals_to_zero_flag being 0, the aforementioned spti_source_type_present_flag, spti_source_type, spti_time_scale, spti_num_units_in_elemental_interval, etc. can be signaled.

[0129] When spti_source_picture_interval_equals_to_zero_flag is defined, spti_source_type in Table 4 can be defined as in Table 5 below. That is, still images may not be included in the multiple pre-defined timing relations.

[0130] bitMaskInterpretation0x01Slow motion: The absolute value of the temporal distance between consecutive source pictures is likely to be less than the temporal distance between corresponding decoded output pictures.0x02Sped-up motion: The absolute value of the temporal distance between consecutive source pictures is likely to be greater than the temporal distance between corresponding decoded output pictures.0x04High-speed imaging: The absolute value of the temporal distance between consecutive source pictures is likely to be less than 1 / 120 seconds.0x08Time-lapse imaging: The temporal distance between source pictures is likely to be greater than 1.001 / 24 seconds.0x10Temporal reversal: The absolute value of the temporal distance between consecutive source pictures is indicated to be negative (i.e., decoded pictures are output in reverse temporal order relative to the timing of the corresponding source pictures).0x20Sporadic or event-driven: The temporal distance between source pictures is likely to be non-constant.

[0131] The values ​​of spti_source_type according to Table 4 may be constrained to fall in the range of 0 to 63. The values ​​64 to 255 for spti_source_type are reserved for future use, and decoders of certain specifications must ignore SPTI SEI messages with spti_source_type in the range of 64 to 255.

[0132] Alternatively, spti_num_units_in_elemental_interval may be allowed to have a value of 0.

[0133] The SPTI SEI message may include information on the number of temporal sublayers (spti_max_sublayers_minus_1). The value of spti_max_sublayers_minus_1 plus 1 may indicate the maximum number of temporal sublayers for which at least one of the scale factor information (spti_sublayer_interval_scale_factor[i]) or the synthesis flag information (spti_sublayer_synthesized_picture_flag[i]) described later is signaled. If spti_max_sublayers_minus_1 does not exist, the value of spti_max_sublayers_minus_1 may be derived as the same value as the temporal identifier (TemporalId).

[0134] spti_max_sublayers_minus_1 may be adaptively signaled based on the aforementioned spti_persistence_flag. For example, based on spti_persistence_flag being 1, spti_max_sublayers_minus_1 may be signaled. Based on spti_persistence_flag being 0, spti_max_sublayers_minus_1 may not be signaled.

[0135] The SPTI SEI message may include scale factor information (spti_sublayer_interval_scale_factor[i]). The scale factor information may specify a scale factor for determining the source picture interval of a picture belonging to the current temporal sublayer.

[0136] For example, spti_sublayer_interval_scale_factor[i] may specify a scale factor used to determine the source picture interval of a picture whose TemporalId is i in the CLVS, based on a previous output picture whose TemporalId is less than or equal to i. When spti_sublayer_interval_scale_factor[i] is 0, this may indicate that the source picture corresponding to the currently decoded output picture is the same as the source picture corresponding to the previous decoded output picture whose TemporalId is less than or equal to i.

[0137] Based on the previous output picture whose TemporalId is less than or equal to i, the source picture interval associated with the output picture whose TemporalId is i can be derived in seconds as shown in the following mathematical expression 3. The source picture interval can be represented by the variable SourcePictureInterval[i].

[0138] [Equation 3]

[0139] SourcePictureInterval[i] = ElementalSourcePictureInterval * spti_sublayer_interval_scale_factor[i] * ( 1 - 2 * temporalReversalFlag )

[0140] When spti_source_type_present_flag is 1, the variable temporalReversalFlag can be derived based on spti_source_type. For example, when the value of (spti_source_type & 0x10) is greater than 0 (i.e., when the timing relationship according to spti_source_type corresponds to temporal reversal), temporalReversalFlag can be derived as 1, otherwise, temporalReversalFlag can be derived as 0. When spti_source_type_present_flag is 0, temporalReversalFlag can be derived as 0.

[0141] The SPTI SEI message may include synthesis flag information (spti_sublayer_synthesized_picture_flag[i]). If spti_sublayer_synthesized_picture_flag[i] is 1, it may provide an indication that the decoded output pictures belonging to the i-th temporal sublayer are synthesized and do not correspond to the original source picture. If spti_sublayer_synthesized_picture_flag[i] is 0, it may not provide the aforementioned indication. If spti_sublayer_synthesized_picture_flag[i] does not exist, it may be set to 0.

[0142] At least one of spti_source_type_present_flag, spti_source_type, spti_time_scale, spti_num_units_in_elemental_interval, spti_max_sublayers_minus_1, spti_sublayer_interval_scale_factor[i], or spti_sublayer_synthesized_picture_flag[i] may be adaptively signaled based on the aforementioned spti_source_timing_equals_output_timing_flag.

[0143] For example, at least one of spti_source_type_present_flag, spti_source_type, spti_time_scale, spti_num_units_in_elemental_interval, spti_max_sublayers_minus_1, spti_sublayer_interval_scale_factor[i], or spti_sublayer_synthesized_picture_flag[i] can be signaled based on spti_source_timing_equals_output_timing_flag being 0. At least one of spti_source_type_present_flag, spti_source_type, spti_time_scale, spti_num_units_in_elemental_interval, spti_max_sublayers_minus_1, spti_sublayer_interval_scale_factor[i], or spti_sublayer_synthesized_picture_flag[i] may not be signaled based on spti_source_timing_equals_output_timing_flag being 0.

[0144] Source picture timing information according to the present disclosure may be configured in an SEI message of a bitstream. The SEI message may be included in a network abstraction layer (NAL) unit of the bitstream. However, the present disclosure is not limited thereto. For example, the source picture timing information according to the present disclosure may be configured in a high level syntax of the bitstream. Here, the high level syntax may be at least one of a sequence parameter set (SPS), a picture parameter set (PPS), a picture header (PH), or a slice header (SH). Alternatively, the source picture timing information according to the present disclosure may be defined as a separate NAL unit type in the bitstream.

[0145] FIG. 5 illustrates a schematic configuration of a decoding device (300) that performs a method for restoring a video picture according to the present disclosure.

[0146] Referring to FIG. 5, the decoding device (300) may include a receiving unit (500), a video information extraction unit (510), and a video restoration unit (520).

[0147] The receiving unit (500) can receive a bitstream including an encoded video picture.

[0148] The video information extraction unit (510) can extract video information about an encoded video picture from a bitstream. In addition, the video information extraction unit (710) can extract an SPTI SEI message from the bitstream, as described with reference to FIG. 4.

[0149] The video restoration unit (520) can restore an encoded video picture based on the extracted video information.

[0150] FIG. 6 illustrates a method for generating a bitstream performed in an encoding device (200) according to the present disclosure.

[0151] A video picture to be encoded can be received (S600).

[0152] The received video picture can be encoded to generate video information about the video picture (S610).

[0153] A bitstream including video information about a video picture can be generated (S420).

[0154] Additionally, a SPTI SEI message applied to a bitstream can be generated, as described with reference to FIG. 4. The generated SPTI SEI message can be included in the bitstream.

[0155] FIG. 7 illustrates a schematic configuration of an encoding device (200) that performs a method for generating a bitstream according to the present disclosure.

[0156] Referring to FIG. 7, the encoding device (200) may include a receiving unit (700), a video compression unit (710), and a bitstream generation unit (720).

[0157] The receiving unit (700) can receive one or more video pictures to be encoded.

[0158] The video compression unit (710) can encode one or more received video pictures to generate video information about the video pictures. The video compression unit (710) can generate an SPTI SEI message applied to the bitstream.

[0159] The bitstream generation unit (720) can generate a bitstream including the video information. The bitstream generation unit (720) can generate a bitstream further including the generated SPTI SEI message.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] FIG. 8 illustrates an example of a content streaming system to which embodiments of the present disclosure can be applied.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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 bitstream including an encoded video picture; and A step of restoring an encoded video picture included in the above bitstream, The above bitstream is configured to include a source picture timing information (SPTI) SEI (supplemental enhancement information) message, The above SPTI SEI message includes source type information, The above source type information indicates a timing relationship between source pictures and decoded output pictures corresponding to the source pictures, A method wherein the SPTI SEI message is obtained from a NAL (network abstraction layer) unit of the bitstream.

2. In paragraph 1, The above source type information specifies at least one of a plurality of pre-defined timing relationships, A method wherein the plurality of timing relationships include at least one of slow motion, sped-up motion, high-speed imaging, time-lapse imaging, time reversal, still image, or single-shot timing.

3. In paragraph 2, A method wherein the above source type information is restricted so as not to simultaneously display the slow motion and the speed-up motion.

4. In paragraph 2, A method wherein the source type information is limited to not simultaneously displaying the high-speed imaging and the time-lapse imaging.

5. In paragraph 2, A method wherein the source type information is restricted so as not to simultaneously represent the still image and at least one other timing relation belonging to the plurality of timing relations.

6. In paragraph 1, The above SPTI SEI message further includes a slow motion flag, A method wherein the slow motion flag indicates whether the timing relationship between the source pictures and the decoded output pictures is slow motion.

7. In paragraph 1, The above SPTI SEI message further includes a high-speed imaging flag, A method wherein the high-speed imaging flag indicates whether the timing relationship between the source pictures and the decoded output pictures is high-speed imaging.

8. In paragraph 1, The above SPTI SEI message further includes time unit count information, The above time unit number information is a method that indicates the number of time units of a clock operating at a predetermined frequency.

9. In paragraph 8, The above time unit count information is signaled based on the source picture interval flag, A method wherein the source picture interval flag having a value of 1 indicates that both the basic source picture interval and the source picture interval are 0, and the source picture interval flag having a value of 0 indicates that information indicating the basic source picture interval and the source picture interval follows.

10. In paragraph 8, A method in which the above time unit count information is allowed to have a value of 0.

11. A step of receiving a video picture to be encoded; A step of encoding the received video picture to generate video information about the video picture; A step of generating a source picture timing information (SPTI) SEI (supplemental enhancement information) message; and A step of generating a bitstream including the above video information and the above SPTI SEI message, The above SPTI SEI message includes source type information, The above source type information indicates a timing relationship between source pictures and decoded output pictures corresponding to the source pictures, A method wherein the above SPTI SEI message is encoded in a NAL (network abstraction layer) unit of the bitstream.

12. A non-transitory computer-readable storage medium storing a bitstream generated by the method according to Article 11.

13. 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 video information about the video picture; and generating a source picture timing information (SPTI) SEI (supplemental enhancement information) message; and Including a step of transmitting data including the above bitstream, The above SPTI SEI message includes source type information, The above source type information indicates a timing relationship between source pictures and decoded output pictures corresponding to the source pictures, A method wherein the above SPTI SEI message is encoded in a NAL (network abstraction layer) unit of the bitstream.

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