Video encoding / decoding method and bitstream generation method

Abstract

Provided are a video encoding method, a video decoding method, and a bitstream generating method using an identifier indicating whether a corresponding chroma component is filtered by an adaptive loop filter (ALF).SOLUTION: The video encoding method includes encoding an image to generate a bitstream. In the bitstream, a first syntax element is configured to indicate whether the first chromaticity component is filtered with an adaptive loop filter (ALF), and a second syntax element is configured to indicate whether the second chromaticity component is filtered with the ALF.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to the field of video encoding technology, and more particularly to a video encoding / decoding method, apparatus, and recording medium. [Background technology]

[0002] Adaptive Loop Filter (ALF) is one of the key technologies in video coding. This technology reduces the compression artifacts of decoded images by encoding filter coefficients and filtering the reconstructed image at the decoding side, and also provides high-quality predicted reference images for subsequent coded and decoded images, thereby further improving compression efficiency.

[0003] In conventional adaptive loop filter technology, each chromaticity component of an image corresponds to a filter control switch, and each filter control switch controls each chromaticity component of the image. This method of combining filter control switches for each chromaticity component into one affects the consistency and readability of each chromaticity component during the encoding process, which in turn affects the efficiency and flexibility of video encoding. Therefore, research is focused on how to appropriately improve the efficiency and flexibility of video encoding. Summary of the Invention [Problem to be solved by the invention]

[0004] Embodiments of the present invention provide a method, apparatus, and recording medium for video encoding and decoding, which simplify the process of writing syntax elements in an encoder and reading syntax elements in a decoder, and improve the flexibility and efficiency of video encoding / decoding. [Means for solving the problem]

[0005] In a first aspect, an embodiment of the present invention provides a video encoding method, the video encoding method comprising: obtaining color components of an image sequence, the color components including two chromaticity components; filtering reconstructed blocks of color components of at least some images of said image sequence with an adaptive loop filter technique; generating a bitstream for the image sequence, in which for the two chrominance components, different identifiers are used in image-level syntax elements to indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF, respectively.

[0006] In a second aspect, embodiments of the present invention provide a video decoding method, the video decoding method comprising: obtaining a bitstream of an image sequence, wherein an image of the image sequence includes two chrominance components, and in the bitstream, for the two chrominance components, using different identifiers in an image level syntax element to respectively indicate whether the corresponding chrominance component is filtered with ALF; parsing from said bitstream identifiers corresponding respectively to two chrominance components of the current image; and determining whether to filter the reconstructed blocks of the two chrominance components of the current image with ALF based on the identifiers corresponding to the two chrominance components, respectively.

[0007] In a third aspect, embodiments of the present invention provide another video encoding method, the video encoding method comprising: obtaining color components of an image sequence, the color components including two chromaticity components; filtering reconstructed blocks of color components of at least some images of the image sequence with ALF; generating a bitstream for the image sequence, wherein for each chroma component of the two chroma components, in an image block level syntax element of the bitstream, a first identifier indicates whether the chroma component is filtered with ALF, and if the first identifier indicates that the chroma component is filtered with ALF, a second identifier indicates an ALF filter to be used for the chroma component.

[0008] In a fourth aspect, embodiments of the present invention provide another video decoding method, the video decoding method comprising: obtaining a bitstream of an image sequence, wherein an image of the image sequence includes two chrominance components, and for each chrominance component of the two chrominance components, in an image block level syntax element of the bitstream, a first identifier indicates whether the chrominance component is filtered with ALF, and a second identifier indicates an ALF filter used for the chrominance component; parsing the first and second identifiers from the bitstream, which correspond respectively to two chrominance components of the current image; For each chrominance component of the current image block, determining whether to filter the reconstructed block of the chrominance component using ALF based on the first identifier corresponding to the chrominance component, and if so, determining to filter the reconstructed block of the chrominance component with the corresponding ALF filter based on the second identifier.

[0009] In a fifth aspect, an embodiment of the present invention provides a video encoding device including a memory and a processor.

[0010] The memory is for storing a program.

[0011] The processor is for calling the program and, when the program is executed, performing the following operations:

[0012] A color component of an image sequence is obtained, the color component including two chromaticity components.

[0013] Reconstructed blocks of color components of at least some images of the image sequence are filtered with an adaptive loop filter technique.

[0014] A bitstream is generated for the image sequence, where in the bitstream, for the two chrominance components, different identifiers are used in image-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF.

[0015] In a sixth aspect, an embodiment of the present invention provides a video decoding device including a memory and a processor.

[0016] The memory is for storing a program.

[0017] The processor is for calling the program and, when the program is executed, performing the following operations:

[0018] A bitstream of an image sequence is obtained, where an image of the image sequence includes two chrominance components, and in the bitstream, for the two chrominance components, different identifiers are used in image-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered with ALF.

[0019] The bitstream is parsed to identify identifiers corresponding to the two chrominance components of the current image.

[0020] Based on the identifiers respectively corresponding to the two chrominance components, it is determined whether the reconstructed blocks of the two chrominance components of the current image are filtered by ALF.

[0021] In a seventh aspect, an embodiment of the present invention provides another video encoding device including a memory and a processor.

[0022] The memory is for storing a program.

[0023] The processor is for calling the program and, when the program is executed, performing the following operations:

[0024] A color component of an image sequence is obtained, the color component including two chromaticity components.

[0025] Reconstructed blocks of color components of at least some images of the image sequence are filtered with ALF.

[0026] generating a bitstream for the image sequence, wherein, for each chroma component of the two chroma components, an image block level syntax element of the bitstream indicates by a first identifier whether the chroma component is filtered with ALF, and if the first identifier indicates that the chroma component is filtered with ALF, by a second identifier an ALF filter to be used for the chroma component.

[0027] In an eighth aspect, an embodiment of the present invention provides another video decoding device including a memory and a processor.

[0028] The memory is for storing a program.

[0029] The processor is for calling the program and, when the program is executed, performing the following operations:

[0030] A bitstream of an image sequence is obtained, where images of the image sequence include two chrominance components, and for each chrominance component of the two chrominance components, an image block level syntax element of the bitstream indicates whether the chrominance component is filtered with ALF by a first identifier and indicates the ALF filter used for the chrominance component by a second identifier.

[0031] The first identifier and the second identifier, which respectively correspond to two chrominance components of the current image, are parsed from the bitstream.

[0032] For each chrominance component of the current image block, it is determined whether to filter the reconstructed block of the chrominance component using ALF based on the first identifier corresponding to the chrominance component, and if it is determined to use ALF, it is determined to filter the reconstructed block of the chrominance component with the corresponding ALF filter based on the second identifier.

[0033] In a ninth aspect of the present disclosure, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, the computer program being configured to implement the video encoding method according to the first and third aspects and the video decoding method according to the second and fourth aspects when executed by a processor.

[0034] In an embodiment of the present invention, color components of an image sequence are obtained, and the reconstructed blocks of the color components of at least some images of the image sequence are filtered using an adaptive loop filter technique to generate a bitstream of the image sequence, where in the bitstream, for two chrominance components of the color components, different identifiers are used in image-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF, thereby simplifying the processes of writing syntax elements in an encoder and reading syntax elements in a decoder, and improving the flexibility and efficiency of video encoding / decoding.

[0035] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the accompanying drawings necessary for the embodiments. It is obvious that the accompanying drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these accompanying drawings without expending creative efforts. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a diagram illustrating the principle of a Wiener filter. [Figure 2] FIG. 10 is a diagram illustrating the shape of an adaptive loop filter. [Figure 3] FIG. 10 illustrates the flow of a cross-component adaptive loop filter. [Figure 4] FIG. 10 is a diagram illustrating the filter shape of a cross-component adaptive loop filter. [Figure 5] FIG. 1 is a flow diagram of a video encoding method provided by an embodiment of the present invention. [Figure 6] FIG. 2 is a flow diagram of a video decoding method provided by an embodiment of the present invention. [Figure 7] FIG. 2 is a flow diagram of another video encoding method provided by an embodiment of the present invention. [Figure 8] FIG. 10 is a flow diagram of another video decoding method provided by an embodiment of the present invention. [Figure 9] FIG. 1 is a diagram illustrating the structure of a video encoding device provided by an embodiment of the present invention. [Figure 10] FIG. 1 is a diagram illustrating the structure of a video decoding device provided by an embodiment of the present invention. [Figure 11] FIG. 2 is a diagram illustrating the structure of another video encoding device provided by an embodiment of the present invention. [Figure 12] FIG. 10 is a diagram illustrating the structure of another video decoding device provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] The following clearly and completely describes the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings of the embodiments of the present invention. It is clear that the described embodiments are only a part of the embodiments of the present invention, and are not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without any creative efforts are all included in the protection scope of the present invention.

[0038] Hereinafter, several embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments and features of the embodiments may be combined with each other if there is no contradiction.

[0039] The video encoding method provided by the embodiments of the present invention can be applied to a video encoding device. The video encoding device can be installed in a smart terminal (such as a mobile phone or a tablet computer). In some embodiments, the embodiments of the present invention can be applied to an air vehicle (e.g., an unmanned aerial vehicle), and in other embodiments, the embodiments of the present invention can also be applied to other mobile platforms (such as an unmanned ship, an unmanned vehicle, a robot, etc.). The embodiments of the present invention are not specifically limited.

[0040] This invention is used in the adaptive loop filter (ALF) technology of the in-loop filter in the video coding standard Versatile Video Coding (VVC). It mainly optimizes the adaptive loop filter technology and the cross-component adaptive loop filter (CCALF) technology, eliminating redundancy and making the design more rational. It is mainly applied to codecs that comply with the international video coding standard H.264, High Efficiency Video Coding (HEVC), and the Chinese AVS2 standard, etc., and can be used to improve the quality of compressed video, which is of great significance for video compression processing in broadcast television, video conferencing, network video, etc.

[0041] Before describing the embodiments of the present invention, the adaptive loop filter technique ALF will first be described.

[0042] Loop filters are an important part of the video encoding / decoding framework and are primarily used to reduce compression artifacts, such as blockiness and ringing, that occur during the encoding process. Examples include three loop filter technologies: deblocking filters, adaptive sample compensation filters, and adaptive loop filters. The deblocking filter and adaptive sample compensation filter are adapted from HEVC. The deblocking filter is used at the boundary between the prediction unit and the transform unit. Blockiness is reduced by nonlinearly weighting the boundary pixels using a trained low-pass filter. The adaptive sample compensation filter classifies pixels within an image block and applies the same compensation value to each type of pixel, thereby reducing ringing artifacts by bringing the reconstructed image closer to the original image.

[0043] In one embodiment, the adaptive loop filter is a Wiener filter, which is primarily used to minimize the mean square error between the original image and the reconstructed image. The adaptive loop filter is a mean square optimal filter calculated based on the original signal and the coded distorted signal, and is essentially a Wiener filter, as shown in Figure 1. Figure 1 illustrates the principle of the Wiener filter. In Figure 1, X is the original signal, e is noise or distortion, and Y is the distorted signal.

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[0044] In one embodiment, in one exemplary ALF, a weighted average of surrounding pixel points is used to obtain the filtered result of the current point. The positions of the neighboring pixel points used are as shown in FIG. 2. FIG. 2 is a diagram illustrating the shape of the adaptive loop filter. As shown in FIG. 2, a 5x5 diamond and a 7x7 diamond are included. If the point corresponding to C12 is the current filtering target point, the filtering process is obtained by using a weighted average of all position points in FIG. 2. The filter coefficients are the weights of each point, and there are a total of 13 filter coefficients C0 to C12. The final filtering process is the cumulative sum of the products of each point in FIG. 2 and its corresponding filter coefficient. Here, all points used in this process are points in the reconstructed frame acquired before the ALF.

[0045] In one embodiment, CCALF adjusts the chrominance components using the values ​​of the luma components to improve the quality of the chrominance components. In some embodiments, CCALF is a linear ALF, and in some embodiments, CCALF processes only the chrominance components and does not modify the values ​​of the luma components.

[0046] In some embodiments, CCALF uses the luma component before ALF to filter the chroma component after ALF. CCALF calculates filter coefficients using both the luma and chroma components and uses the calculated filter coefficients to filter the chroma component. An overall flowchart of CCALF filtering is shown in FIG. 3. FIG. 3 is a diagram showing the flow of a cross-component adaptive loop filter. First, the luma and chroma Cb and Cr of an image are filtered using ALF, and then the chroma Cb and Cr of the image are filtered using CCALF. Then, the filtered chroma Cb and Cr are determined based on the results obtained by filtering the chroma Cb and Cr of the image using CCALF and the results obtained by filtering the chroma Cb and Cr of the image using ALF.

[0047] In one embodiment, the shape of the CCALF filter is as shown in Figure 4. Figure 4 is a diagram showing the filter shape of a cross-component adaptive loop filter. As shown in Figure 4, the shape of the CCALF filter can be a 3x4 diamond with a total of eight coefficients. If position 2 is the pixel point of the current Cb or Cr component, the weighted average of the seven points surrounding 2 can be used to obtain the filtered result of the pixel point at position 2.

[0048] Currently, when two chrominance components are filtered with ALF, the bitstream of the generated image sequence uses the same identifier for both chrominance components to indicate whether the corresponding chrominance component is filtered with ALF or not.

[0049] In one embodiment, the bitstream indicates, for the two chrominance components, whether the two chrominance components are ALF filtered by the same identifier in the image-level syntax element. For example, the bitstream indicates, for the two chrominance components, whether the two chrominance components are ALF filtered by the same identifier ph_alf_chroma_idc in the image-level syntax element. Here, ph_alf_chroma_idc = 0 indicates that neither of the two chrominance components, Cb and Cr, is ALF filtered. ph_alf_chroma_idc = 1 indicates that the Cb chrominance component is ALF filtered and the Cr chrominance component is not ALF filtered. ph_alf_chroma_idc = 2 indicates that the Cb chrominance component is not ALF filtered and the Cr chrominance component is ALF filtered. ph_alf_chroma_idc = 3 indicates that both the Cb and Cr chrominance components are ALF filtered.

[0050] In one embodiment, the bitstream indicates, for the two chrominance components, whether the two chrominance components are ALF filtered using the same identifier in an image-level syntax element. For example, the bitstream indicates, for the two chrominance components, whether the two chrominance components are ALF filtered using the same identifier slice_alf_chroma_idc in an image-level syntax element. Here, slice_alf_chroma_idc = 0 indicates that neither of the two chrominance components, Cb and Cr, is ALF filtered. slice_alf_chroma_idc = 1 indicates that the Cb chrominance component is ALF filtered and the Cr chrominance component is not ALF filtered. slice_alf_chroma_idc = 2 indicates that the Cb chrominance component is not ALF filtered and the Cr chrominance component is ALF filtered. slice_alf_chroma_idc = 3 indicates that both the Cb and Cr chrominance components are ALF filtered.

[0051] In one embodiment, in the bitstream, for the two chrominance components, an identifier alf_ctb_cc_cb_idc is used in the image block level syntax element to indicate whether the chrominance component Cb is filtered with CCALF, and an identifier alf_ctb_cc_cr_idc is used to indicate whether the chrominance component Cr is filtered with CCALF. Taking alf_ctb_cc_cb_idc as an example, if alf_ctb_cc_cb_idc is 0, it indicates that the Cb chrominance component is not filtered with CCALF. If alf_ctb_cc_cb_idc is greater than 0, it indicates that the Cb chrominance component is filtered with CCALF.

[0052] In this way, if the same identifier is used to indicate whether or not to filter with the adaptive loop filter ALF, redundancy increases, which affects the consistency and readability of the coded chrominance components.

[0053] To address the above-mentioned problem, an embodiment of the present invention removes the unified identifier used for each chrominance component in the conventional ALF and redesigns the syntax elements, setting different identifiers for each chrominance component in the ALF to indicate whether the corresponding chrominance component is filtered by the ALF. This simplifies the process of writing syntax elements in the encoder and reading syntax elements in the decoder, and is advantageous in improving the flexibility and efficiency of video encoding / decoding.

[0054] In one embodiment, for ALF chromaticity components at the image level, the embodiment of the present invention removes ph_alf_chroma_idc and indicates whether the Cb chromaticity components are filtered with ALF or not with ph_alf_cb_enabled_flag and whether the Cr chromaticity components are filtered with ALF or not with ph_alf_cr_enabled_flag.

[0055] In one embodiment, for ALF chromaticity components at slice level, the embodiment of the present invention removes slice_alf_chroma_idc and indicates whether the Cb chromaticity components are filtered with ALF or not with slice_alf_cb_enabled_flag, and whether the Cr chromaticity components are filtered with ALF or not with slice_alf_cr_enabled_flag.

[0056] In one embodiment, for the ALF chromaticity components at the CTU level, the present invention uses two identifiers, alf_ctb_cc_cb_flag and alf_ctb_cc_cb_idx, for the Cb chromaticity component to indicate whether the Cb chromaticity component is filtered with CCALF. Here, the alf_ctb_cc_cb_flag identifier indicates whether CCALF is used for the Cb chromaticity component, and if so, the alf_ctb_cc_cb_idx identifier indicates the index of the CCALF filter used for the Cb chromaticity component. Similarly, the present invention uses two identifiers, alf_ctb_cc_cr_flag and alf_ctb_cc_cr_idx, for the Cr chromaticity component to indicate whether the Cr chromaticity component is filtered with CCALF. Here, the alf_ctb_cc_cr_flag identifier indicates whether or not CCALF is used for the Cr chromaticity component, and if it is used, the alf_ctb_cc_cr_idx identifier is further used to indicate the index of the CCALF filter used for the Cr chromaticity component.

[0057] In this manner, such an embodiment of an embodiment of the present invention can reduce redundancy, simplify the process of writing syntax elements in the encoder and reading syntax elements in the decoder, and improve the flexibility and efficiency of video encoding / decoding.

[0058] Hereinafter, a video encoding and decoding method provided by an embodiment of the present invention will be briefly described in conjunction with the accompanying FIGS.

[0059] Please refer to Fig. 5 for details. Fig. 5 is a flowchart illustrating a video encoding method according to an embodiment of the present invention. The method can be applied to a video encoding device, where the video encoding device can be installed in a smart terminal. Specifically, the method according to an embodiment of the present invention includes the following steps:

[0060] S501: Obtain color components of an image sequence, where the color components include two chromaticity components.

[0061] In some embodiments of the present invention, a video encoding device may obtain color components of an image sequence, the color components including two chrominance components, and in some embodiments, the two chrominance components include Cb and Cr.

[0062] S502: Filtering reconstructed blocks of color components of at least some images of the image sequence using an adaptive loop filter technique.

[0063] In an embodiment of the present invention, the video coding device is capable of filtering reconstructed blocks of color components of at least some images of the image sequence using an adaptive loop filter technique.

[0064] In one embodiment, when filtering a reconstructed block of a color component of at least a portion of an image in the image sequence using an adaptive loop filter technique, the video encoding device may obtain a pixel value of each pixel point in the reconstructed block of a color component of at least a portion of an image in the image sequence, determine a filter coefficient for each pixel point in the reconstructed block, and obtain a filtered result by accumulating the product of the pixel value of each pixel point and its corresponding filter coefficient using the filter coefficient for each pixel point as a weight.

[0065] In one embodiment, the filter coefficients are determined based on the categories of pixel points by classifying the pixel points. Here, pixel points of the same category correspond to the same filter coefficient set. Taking the 5x5 diamond in Figure 2 as an example, the reconstruction block has a total of seven filter coefficients C0 to C6, and pixel points corresponding to the same filter coefficient belong to the same type.

[0066] In some embodiments, there are several ways to classify pixel points, and no specific limitations are imposed in the embodiments of the present invention. Take one exemplary conventional classification method as an example. In the prior art, only the luminance Y component is classified, and the chrominance U and V components are not classified. Among them, the Y component can be divided into 25 types, but the U and V components each have only one type. This means that for one frame of image, the Y component can have a maximum of 25 sets of filters, but the U and V components only have one set.

[0067] In one embodiment, each 4x4 block is sorted based on the Laplacian direction.

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[0071] S503: Generate a bitstream of the image sequence, where in the bitstream, for the two chrominance components, different identifiers are used in image-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF.

[0072] In an embodiment of the present invention, the video encoding device may generate a bitstream of the image sequence, where in the bitstream, for the two chrominance components, different identifiers are used in a picture-level syntax element to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF.

[0073] In one embodiment, the bitstream may use an identifier ph_alf_cb_enabled_flag in the picture level syntax element for the chrominance component Cb, which is used to indicate whether the chrominance component Cb is filtered by the adaptive loop filter ALF.

[0074] In one embodiment, the bitstream may use an identifier ph_alf_cr_enabled_flag in the picture level syntax element for the chrominance component Cr, which is used to indicate whether the chrominance component Cr is filtered by the adaptive loop filter ALF.

[0075] Here, the chromaticity components Cb and Cr are represented in the image level syntax elements as shown in Table 1 below.

[0076] [Table 1]

[0077] In one embodiment, the bitstream uses different identifiers in the slice level syntax element for the two chrominance components to respectively indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF.

[0078] In one embodiment, the bitstream may use an identifier slice_alf_cb_enabled_flag in a slice level syntax element for the chrominance component Cb, which is used to indicate whether the chrominance component Cb is filtered by the adaptive loop filter ALF.

[0079] In one embodiment, the bitstream may use an identifier slice_alf_cr_enabled_flag in a slice level syntax element for the chrominance component Cr, which is used to indicate whether the chrominance component Cr is filtered by the adaptive loop filter ALF.

[0080] Here, the chromaticity components Cb and Cr are represented in the slice level syntax elements as shown in Table 2 below.

[0081] [Table 2]

[0082] In one embodiment, in the bitstream, for each chroma component of the two chroma components, a first identifier indicates whether the chroma component is filtered using ALF, and a second identifier indicates the ALF filter used for the chroma component if the first identifier indicates that the chroma component is filtered using ALF. In some embodiments, the ALF filter is a CCALF filter for cross-component adaptive loop filtering. In some embodiments, the image block level is a coding tree unit (CTU) level. Here, the coding tree unit CTU includes a luma coding tree block (CTB), two chroma coding tree blocks CTB, and a syntax element.

[0083] In one embodiment, the bitstream may use alf_ctb_cc_cb_flag as a first identifier in an image block level syntax element for the chrominance component Cb, which is used to indicate whether the chrominance component Cb is filtered by the adaptive loop filter CCALF. If filtered by the adaptive loop filter CCALF, alf_ctb_cc_cb__idx is further used as a second identifier to identify the index of the CCALF filter used for the chrominance component Cb.

[0084] In one embodiment, the bitstream may use alf_ctb_cc_cr_flag as a first identifier in an image block level syntax element for the chroma component Cr, which is used to indicate whether the chroma component Cr is filtered with the adaptive loop filter CCALF. If filtered with the adaptive loop filter CCALF, the bitstream further uses alf_ctb_cc_cr__idx as a second identifier to identify the index of the CCALF filter used for the chroma component Cr. In some embodiments, the second identifier is calculated based on the first identifier. In some embodiments, if it is determined in the image block level syntax element that the chroma component is filtered with CCALF, the second identifier may be determined based on a difference between the first identifier and 1.

[0085] Here, the chrominance components Cb and Cr are represented in the image block level syntax elements as shown in Table 3 below.

[0086] [Table 3]

[0087] In an embodiment of the present invention, a video encoding device may obtain color components of an image sequence including two chrominance components, filter the reconstructed blocks of the color components of at least some images of the image sequence using an adaptive loop filter technique, and generate a bitstream of the image sequence. In the bitstream, different identifiers are used in image-level syntax elements for the two chrominance components to indicate whether the corresponding chrominance components are filtered by the adaptive loop filter (ALF). This embodiment simplifies the process of writing syntax elements in an encoder by using different identifiers for ALF filtering, thereby improving the efficiency and flexibility of video encoding.

[0088] Please refer to Figure 6. Figure 6 is a flow diagram of a video decoding method provided by an embodiment of the present invention. The method can be applied to a video decoding device, where the video decoding device can be installed in a smart terminal (such as a mobile phone or a tablet computer). Specifically, the method of the embodiment of the present invention includes the following steps:

[0089] S601: Obtain a bitstream of an image sequence, where an image of the image sequence includes two chrominance components, and in the bitstream, for the two chrominance components, use different identifiers in image-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by ALF.

[0090] In an embodiment of the present invention, a video decoder may obtain a bitstream of an image sequence, where an image of the image sequence includes two chrominance components, and in the bitstream, for the two chrominance components, different identifiers are used in image-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered using ALF.

[0091] In one embodiment, the bitstream uses different identifiers in slice-level syntax elements for the two chrominance components to respectively indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF.

[0092] In one embodiment, in the bitstream, for each chroma component of the two chroma components, a first identifier indicates whether the chroma component is filtered with ALF, and a second identifier indicates the ALF filter used for the chroma component if the first identifier indicates that the chroma component is filtered with ALF. In some embodiments, the ALF filter is a CCALF filter for cross-component adaptive loop filtering. In some embodiments, the image block level is a coding tree unit (CTU) level.

[0093] S602: Parse identifiers respectively corresponding to two chrominance components of the current image from the bitstream.

[0094] In an embodiment of the present invention, the video decoder can parse identifiers respectively corresponding to two chrominance components of the current image from the bitstream.

[0095] In one embodiment, the video decoding device may at least one of parse first identifiers from the bitstream, each corresponding to two chrominance components of the current image, in a contextual manner, or parse second identifiers from the bitstream, each corresponding to two chrominance components of the current image, in a truncated unary manner.

[0096] S603: Determine whether to filter the reconstructed blocks of the two chrominance components of the current image by ALF, based on the identifiers respectively corresponding to the two chrominance components.

[0097] In an embodiment of the present invention, the video decoding device can determine whether to filter the reconstructed blocks of the two chrominance components of the current image using ALF based on the identifiers corresponding to the two chrominance components, respectively.

[0098] In an embodiment of the present invention, a video decoder may obtain a bitstream of an image sequence, where an image of the image sequence includes two chrominance components. In the bitstream, for the two chrominance components, different identifiers are used in image-level syntax elements to indicate whether the corresponding chrominance components are to be filtered using ALF. The bitstream is analyzed to identify identifiers corresponding to the two chrominance components of a current image. Based on the identifiers corresponding to the two chrominance components, the decoder determines whether to filter reconstructed blocks of the two chrominance components of the current image using ALF. This embodiment simplifies the decoder's syntax element reading process by using different identifiers for ALF filtering, thereby improving the efficiency and flexibility of video decoding.

[0099] Please refer to Figure 7. Figure 7 is a flow diagram of another video encoding method provided by an embodiment of the present invention. The method can be applied to a video encoding device, where the video decoding device can be installed in a smart terminal (such as a mobile phone or a tablet computer). Specifically, the method of the embodiment of the present invention includes the following steps:

[0100] S701: Obtain color components of an image sequence, where the color components include two chromaticity components.

[0101] In an embodiment of the present invention, the video encoding device is capable of obtaining color components of an image sequence, the color components including two chrominance components.

[0102] S702: Reconstructed blocks of color components of at least some images of the image sequence are filtered using ALF.

[0103] In some embodiments of the present invention, the video encoding device may filter the reconstructed blocks of color components of at least some images in the image sequence using ALF. In some embodiments, the process by which the video encoding device filters the reconstructed blocks of color components of at least some images in the image sequence using ALF has been described above, and therefore will not be described again in detail here.

[0104] S703: Generate a bitstream of the image sequence, where, for each chrominance component of the two chrominance components, in an image block level syntax element of the bitstream, a first identifier indicates whether the chrominance component is filtered with ALF, and if the first identifier indicates that the chrominance component is filtered with ALF, a second identifier indicates an ALF filter used for the chrominance component.

[0105] In some embodiments of the present invention, the video encoding device may generate a bitstream of the image sequence, wherein, for each chroma component of the two chroma components, a first identifier in an image block level syntax element of the bitstream indicates whether the chroma component is filtered using ALF, and if the first identifier indicates that the chroma component is filtered using ALF, a second identifier indicates an ALF filter to be used for the chroma component. In some embodiments, the ALF filter includes a CCALF filter. In some embodiments, the image block level is a coding tree unit (CTU) level.

[0106] In one embodiment, the first identifier is at least one of coded in a contextual manner and the second identifier is coded in a truncated unary manner.

[0107] In one embodiment, the bitstream uses different identifiers in the picture level syntax elements for the two chrominance components to respectively indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF.

[0108] In one embodiment, the bitstream uses different identifiers in slice-level syntax elements for the two chrominance components to respectively indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF.

[0109] In an embodiment of the present invention, a video encoding device may obtain color components of an image sequence including two chrominance components, filter reconstructed blocks of the color components of at least some images in the image sequence using ALF, and generate a bitstream for the image sequence. For each chrominance component of the two chrominance components, a first identifier in an image block-level syntax element of the bitstream indicates whether the chrominance component is filtered using ALF, and if the first identifier indicates that the chrominance component is filtered using ALF, a second identifier indicates an ALF filter to be used for the chrominance component. This embodiment simplifies the process of writing syntax elements in an encoder by using the first and second identifiers when performing CCALF filtering, thereby improving the efficiency and flexibility of video encoding.

[0110] Please refer to Figure 8. Figure 8 is a flow diagram of another video decoding method provided by an embodiment of the present invention. The method can be applied to a video decoding device, where the video decoding device can be installed in a smart terminal (such as a mobile phone or a tablet computer). Specifically, the method of the embodiment of the present invention includes the following steps:

[0111] S801: Obtain a bitstream of an image sequence, where an image of the image sequence includes two chrominance components, and for each chrominance component of the two chrominance components, in an image block level syntax element of the bitstream, a first identifier indicates whether the chrominance component is filtered by ALF, and a second identifier indicates an ALF filter used for the chrominance component.

[0112] In some embodiments of the present invention, a video decoder may obtain a bitstream of an image sequence, where the images of the image sequence include two chrominance components. For each chrominance component of the two chrominance components, an image block level syntax element of the bitstream may include a first identifier indicating whether the chrominance component is filtered using ALF, and a second identifier indicating an ALF filter used for the chrominance component. In some embodiments, the ALF filter is a CCALF filter for cross-component adaptive loop filtering, and the image block level is a coding tree unit (CTU) level.

[0113] In one embodiment, the bitstream uses different identifiers in the picture level syntax elements for the two chrominance components to respectively indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF.

[0114] In one embodiment, the bitstream uses different identifiers in slice-level syntax elements for the two chrominance components to respectively indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF.

[0115] S802: The first identifier and the second identifier, which respectively correspond to two chrominance components of the current image, are analyzed from the bitstream.

[0116] In an embodiment of the present invention, the video decoding device can analyze the first identifier and the second identifier from the bitstream, which respectively correspond to two chrominance components of the current image.

[0117] In one embodiment, the video decoding device can parse first identifiers from the bitstream, each corresponding to two chrominance components of the current image, in a contextual manner, and parse second identifiers from the bitstream, each corresponding to two chrominance components of the current image, in a truncated unary manner.

[0118] S803: For each chrominance component of the current image block, determine whether to filter the reconstructed block of the chrominance component using ALF based on the first identifier corresponding to the chrominance component, and if so, determine to filter the reconstructed block of the chrominance component with the corresponding ALF filter based on the second identifier.

[0119] In an embodiment of the present invention, the video decoding apparatus determines, for each chrominance component of the current image block, whether to filter the reconstructed block of the chrominance component using ALF based on the first identifier corresponding to the chrominance component, and if so, determines to filter the reconstructed block of the chrominance component with the corresponding ALF filter based on the second identifier.

[0120] In an embodiment of the present invention, a video decoder may obtain a bitstream of an image sequence, where an image of the image sequence includes two chrominance components. For each chrominance component of the two chrominance components, a first identifier indicates whether the chrominance component is filtered using ALF, and a second identifier indicates the ALF filter used for the chrominance component in an image block-level syntax element of the bitstream. The bitstream is analyzed to find the first and second identifiers corresponding to two chrominance components of a current image. Then, for each chrominance component of a current image block, the decoder determines whether to filter the reconstructed block of the chrominance component using ALF, based on the first identifier corresponding to the chrominance component. If ALF filtering is determined, the decoder determines to filter the reconstructed block of the chrominance component with the corresponding ALF filter, based on the second identifier. This embodiment simplifies the decoder's syntax element reading process by using the first and second identifiers when performing CCALF filtering, thereby improving the efficiency and flexibility of video decoding.

[0121] Please refer to Figure 9. Figure 9 is a diagram showing the structure of a video encoding device provided by an embodiment of the present invention. Specifically, the video encoding device includes a memory 901, a processor 902 and a data interface 903.

[0122] The memory 901 may include a volatile memory, a non-volatile memory, or a combination of the above-mentioned types of memory. The processor 902 may be a central processing unit (CPU). The processor 902 may further include a hardware video encoding device. The hardware video encoding device may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. Specifically, the hardware video encoding device may be, for example, a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), or any combination thereof.

[0123] Furthermore, the memory 901 is for storing a program. When the program is executed, the processor 902 can be used to call the program stored in the memory 901 and perform the following steps:

[0124] A color component of an image sequence is obtained, the color component including two chromaticity components.

[0125] Reconstructed blocks of color components of at least some images of the image sequence are filtered with an adaptive loop filter technique.

[0126] A bitstream is generated for the image sequence, where in the bitstream, for the two chrominance components, different identifiers are used in image-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF.

[0127] Furthermore, in the bitstream, for the two chrominance components, different identifiers are used in the slice-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF.

[0128] Furthermore, in the bitstream, for each chrominance component of the two chrominance components, a first identifier in an image block level syntax element of the bitstream indicates whether the chrominance component is filtered with ALF, and if the first identifier indicates that the chrominance component is filtered with ALF, a second identifier indicates the ALF filter to be used for the chrominance component.

[0129] Furthermore, the ALF filter is a CCALF filter for cross-component adaptive loop filtering.

[0130] Furthermore, the image block level is a coding tree unit (CTU) level.

[0131] Furthermore, the first identifier is coded in a contextual manner, or The second identifier is at least one of encoded in a truncated unary format.

[0132] In an embodiment of the present invention, a video encoding device may obtain color components of an image sequence including two chrominance components, filter the reconstructed blocks of the color components of at least some images of the image sequence using an adaptive loop filter technique, and generate a bitstream of the image sequence. In the bitstream, different identifiers are used in image-level syntax elements for the two chrominance components to indicate whether the corresponding chrominance components are filtered by the adaptive loop filter (ALF). This embodiment simplifies the process of writing syntax elements in an encoder by using different identifiers for ALF filtering, thereby improving the efficiency and flexibility of video encoding.

[0133] Please refer to Figure 10. Figure 10 is a diagram showing the structure of a video decoding device provided by an embodiment of the present invention. Specifically, the video decoding device includes a memory 1001, a processor 1002 and a data interface 1003.

[0134] The memory 1001 may include a volatile memory, a non-volatile memory, or a combination of the above-mentioned types of memory. The processor 1002 may be a central processing unit (CPU). The processor 1002 may further include a hardware video decoder. The hardware video decoder may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. Specifically, the hardware video decoder may be, for example, a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), or any combination thereof.

[0135] Furthermore, the memory 1001 is for storing a program. When the program is executed, the processor 1002 can be used to call the program stored in the memory 1001 and perform the following steps:

[0136] A bitstream of an image sequence is obtained, where an image of the image sequence includes two chrominance components, and in the bitstream, for the two chrominance components, different identifiers are used in image-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered with ALF.

[0137] The bitstream is parsed to identify identifiers corresponding to the two chrominance components of the current image.

[0138] Based on the identifiers respectively corresponding to the two chrominance components, it is determined whether the reconstructed blocks of the two chrominance components of the current image are filtered by ALF.

[0139] Furthermore, in the bitstream, for the two chrominance components, different identifiers are used in the slice-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF.

[0140] Furthermore, in the bitstream, for each chrominance component of the two chrominance components, a first identifier in an image block level syntax element of the bitstream indicates whether the chrominance component is filtered with ALF, and if the first identifier indicates that the chrominance component is filtered with ALF, a second identifier indicates the ALF filter to be used for the chrominance component.

[0141] Furthermore, the ALF filter is a CCALF filter for cross-component adaptive loop filtering.

[0142] Furthermore, when analyzing the identifiers respectively corresponding to the two chrominance components of the current image from the bitstream, the processor 1002 is specifically used to:

[0143] Analyzing first identifiers corresponding to two chrominance components of the current image from the bitstream in a contextual manner; and parsing second identifiers corresponding to two chrominance components of the current image from the bitstream in a truncated unary manner.

[0144] Furthermore, the image block level is a coding tree unit (CTU) level.

[0145] In an embodiment of the present invention, a video decoder may obtain a bitstream of an image sequence, where an image of the image sequence includes two chrominance components. In the bitstream, for the two chrominance components, different identifiers are used in image-level syntax elements to indicate whether the corresponding chrominance components are to be filtered using ALF. The bitstream is analyzed to identify identifiers corresponding to the two chrominance components of a current image. Based on the identifiers corresponding to the two chrominance components, the decoder determines whether to filter reconstructed blocks of the two chrominance components of the current image using ALF. This embodiment simplifies the decoder's syntax element reading process by using different identifiers for ALF filtering, thereby improving the efficiency and flexibility of video decoding.

[0146] Please refer to Figure 11. Figure 11 shows the structure of another video encoding device provided by an embodiment of the present invention. Specifically, the video encoding device includes a memory 1101, a processor 1102 and a data interface 1103.

[0147] The memory 1101 may include volatile memory, non-volatile memory, or a combination of the above types of memory. The processor 1102 may be a central processing unit (CPU). The processor 1102 may further include a hardware video encoding device. The hardware video encoding device may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. Specifically, the hardware video encoding device may be, for example, a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), or any combination thereof.

[0148] Furthermore, the memory 1101 is for storing a program. When the program is executed, the processor 1102 can be used to call the program stored in the memory 1101 and perform the following steps:

[0149] A color component of an image sequence is obtained, the color component including two chromaticity components.

[0150] Reconstructed blocks of color components of at least some images of the image sequence are filtered with ALF.

[0151] generating a bitstream for the image sequence, wherein, for each chroma component of the two chroma components, an image block level syntax element of the bitstream indicates by a first identifier whether the chroma component is filtered with ALF, and if the first identifier indicates that the chroma component is filtered with ALF, by a second identifier an ALF filter to be used for the chroma component.

[0152] Furthermore, the ALF filter is a CCALF filter for cross-component adaptive loop filtering.

[0153] Furthermore, the image block level is a coding tree unit (CTU) level.

[0154] Furthermore, the first identifier is coded in a contextual manner, or The second identifier is at least one of encoded in a truncated unary format.

[0155] Furthermore, in the bitstream, for the two chrominance components, different identifiers are used in the picture level syntax elements to respectively indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF.

[0156] Furthermore, in the bitstream, for the two chrominance components, different identifiers are used in the slice-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF.

[0157] In an embodiment of the present invention, a video encoding device may obtain color components of an image sequence including two chrominance components, filter reconstructed blocks of the color components of at least some images in the image sequence using ALF, and generate a bitstream for the image sequence. For each chrominance component of the two chrominance components, a first identifier in an image block-level syntax element of the bitstream indicates whether the chrominance component is filtered using ALF, and if the first identifier indicates that the chrominance component is filtered using ALF, a second identifier indicates an ALF filter to be used for the chrominance component. This embodiment simplifies the process of writing syntax elements in an encoder by using the first and second identifiers when performing CCALF filtering, thereby improving the efficiency and flexibility of video encoding.

[0158] Please refer to Figure 12. Figure 12 shows the structure of another video decoding device provided by an embodiment of the present invention. Specifically, the video decoding device includes a memory 1201, a processor 1202, and a data interface 1203.

[0159] The memory 1201 may include volatile memory, non-volatile memory, or a combination of the above types of memory. The processor 1202 may be a central processing unit (CPU). The processor 1202 may further include a hardware video decoder. The hardware video decoder may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. Specifically, the hardware video decoder may be, for example, a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), or any combination thereof.

[0160] Furthermore, the memory 1201 is for storing a program. When the program is executed, the processor 1002 can be used to call the program stored in the memory 1201 and perform the following steps:

[0161] A bitstream of an image sequence is obtained, where images of the image sequence include two chrominance components, and for each chrominance component of the two chrominance components, an image block level syntax element of the bitstream indicates whether the chrominance component is filtered with ALF by a first identifier and indicates the ALF filter used for the chrominance component by a second identifier.

[0162] The first identifier and the second identifier, which respectively correspond to two chrominance components of the current image, are parsed from the bitstream.

[0163] For each chrominance component of the current image block, determine whether to filter the reconstructed block of the chrominance component using ALF based on the first identifier corresponding to the chrominance component, and if so, determine to filter the reconstructed block of the chrominance component with the corresponding ALF filter based on the second identifier.

[0164] Furthermore, the ALF filter is a CCALF filter for cross-component adaptive loop filtering.

[0165] Furthermore, the image block level is a coding tree unit (CTU) level.

[0166] Furthermore, when analyzing the first identifier and the second identifier, which respectively correspond to two chrominance components of the current image, from the bitstream, the processor 1002 is specifically used to:

[0167] A first identifier corresponding to each of two chrominance components of the current image is analyzed from the bitstream in a contextual manner.

[0168] Also, second identifiers corresponding to two chrominance components of the current image are parsed from the bitstream in a truncated unary manner.

[0169] Furthermore, in the bitstream, for the two chrominance components, different identifiers are used in the picture level syntax elements to respectively indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF.

[0170] Furthermore, in the bitstream, for the two chrominance components, different identifiers are used in the slice-level syntax elements to respectively indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF.

[0171] In an embodiment of the present invention, the video decoding apparatus determines, for each chrominance component of the current image block, whether to filter the reconstructed block of the chrominance component using ALF based on the first identifier corresponding to the chrominance component, and if so, determines to filter the reconstructed block of the chrominance component with the corresponding ALF filter based on the second identifier.

[0172] An embodiment of the present invention further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the video encoding method and system described in Fig. 5 or 7 according to an embodiment of the present invention. Alternatively, the computer program may implement the video decoding method and system described in Fig. 6 or 8 according to an embodiment of the present invention, the video encoding device according to a corresponding embodiment of the present invention shown in Fig. 9 or 11, or the video decoding device according to a corresponding embodiment of the present invention shown in Fig. 10 or 12, and detailed description thereof will not be repeated here.

[0173] The computer-readable storage medium may be an internal storage unit of the device described in any of the above embodiments, such as a hard disk or memory of the device. The computer-readable storage medium may also be an external storage device of the device, such as a pluggable hard disk attached to the device, a Smart Media Card (SMC), a Secure Digital (SD) card, or a Flash Card. Furthermore, the computer-readable storage medium may include an internal storage unit of the device as well as an external storage device. The computer-readable storage medium is for storing the computer program and other programs and data required by the device. The computer-readable storage medium may also be used to temporarily store data that has been output or will be output.

[0174] As can be understood by those skilled in the art, all or part of the steps in the above-described method embodiments can be realized by instructing related hardware using a computer program. The program can be stored in a computer-readable storage medium. When executed, the program can include the steps in each of the above-described method embodiments. Here, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), etc.

[0175] The above disclosure is merely a partial example of the present invention, and it is obvious that it cannot be used to limit the scope of the present invention. Therefore, any equivalent modifications made in accordance with the claims of the present invention still belong to the scope covered by the present invention. [Item 1] In a video encoding method, obtaining color components of an image sequence, the color components including two chromaticity components; filtering reconstructed blocks of color components of at least some images of said image sequence with an adaptive loop filter technique; generating a codestream for the image sequence, wherein in the codestream, for the two chrominance components, different identifiers are used in image level syntax elements to indicate whether the corresponding chrominance component has been filtered by the adaptive loop filter ALF or not. [Item 2] Item 1. The method according to item 1, characterized in that in the codestream, for the two chrominance components, different identifiers are used in slice-level syntax elements to indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF or not. [Item 3] Item 1. The method according to item 1, wherein in the codestream, for each chrominance component of the two chrominance components, a first identifier indicates whether the chrominance component has been filtered with ALF, and a second identifier indicates the ALF filter used for the chrominance component if the first identifier indicates that the chrominance component has been filtered with ALF. [Item 4] Item 4. The method according to item 3, characterized in that the ALF filter is a CCALF filter for cross-component adaptive loop filtering. [Item 5] 4. The method according to claim 3, wherein the image block level is a coding tree unit (CTU) level. [Item 6] the first identifier is coded in a contextual manner; 4. The method according to claim 3, wherein the second identifier is at least one of encoded in a truncated unary format. [Item 7] In a video decoding method, obtaining a codestream of an image sequence, wherein an image of the image sequence includes two chrominance components, and in the codestream, for the two chrominance components, using different identifiers in image-level syntax elements to respectively indicate whether the corresponding chrominance component is ALF filtered; parsing from said codestream identifiers corresponding respectively to two chrominance components of the current image; determining whether to filter the reconstructed blocks of the two chrominance components of the current image using ALF based on identifiers corresponding to the two chrominance components, respectively. [Item 8] Item 8. The method according to item 7, characterized in that in the codestream, for the two chrominance components, different identifiers are used in slice-level syntax elements to indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF or not. [Item 9] Item 8. The method according to item 7, wherein in the codestream, for each chrominance component of the two chrominance components, a first identifier indicates whether the chrominance component is ALF filtered or not in an image block level syntax element of the codestream, and if the first identifier indicates that the chrominance component is ALF filtered, a second identifier indicates the ALF filter used for the chrominance component. [Item 10] Item 10. The method according to item 9, characterized in that the ALF filter is a CCALF filter for cross-component adaptive loop filtering. [Item 11] said parsing identifiers from said codestream corresponding to two chrominance components of the current image, respectively, comprising: contextually analyzing first identifiers from the codestream, each corresponding to two chrominance components of a current image; and 10. The method according to item 9, characterized in that it includes at least one of parsing second identifiers from the codestream in a truncated unary manner, each corresponding to two chromaticity components of the current image. [Item 12] Item 10. The method according to item 9, wherein the image block level is a coding tree unit (CTU) level. [Item 13] In a video encoding method, obtaining color components of an image sequence, the color components including two chromaticity components; filtering reconstructed blocks of color components of at least some images of the image sequence with ALF; generating a codestream for the image sequence, comprising: for each chrominance component of the two chrominance components, indicating with a first identifier in an image block level syntax element of the codestream whether the chrominance component has been filtered with ALF, and if the first identifier indicates that the chrominance component has been filtered with ALF, indicating with a second identifier the ALF filter used for the chrominance component. [Item 14] Item 14. The method according to item 13, characterized in that the ALF filter is a CCALF filter for cross-component adaptive loop filtering. [Item 15] Item 14. The method according to item 13, wherein the image block level is a coding tree unit (CTU) level. [Item 16] the first identifier is coded in a contextual manner; Item 14. The method according to item 13, wherein the second identifier is at least one of encoded in a truncated unary format. [Item 17] Item 14. The method according to item 13, wherein in the codestream, for the two chrominance components, different identifiers are used in image-level syntax elements to indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF or not. [Item 18] Item 14. The method according to item 13, wherein in the codestream, for the two chrominance components, different identifiers are used in slice-level syntax elements to indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF or not. [Item 19] In a video decoding method, obtaining a codestream of an image sequence, wherein an image of the image sequence includes two chrominance components, and for each chrominance component of the two chrominance components, an image block level syntax element of the codestream indicates whether the chrominance component is ALF filtered by a first identifier and indicates the ALF filter used for the chrominance component by a second identifier; parsing the first and second identifiers from the codestream, which correspond respectively to two chrominance components of the current image; for each chrominance component of a current image block, determining whether to filter the reconstructed block of the chrominance component using ALF based on the first identifier corresponding to the chrominance component, and if it is determined to use ALF, determining to filter the reconstructed block of the chrominance component with the corresponding ALF filter based on the second identifier. [Item 20] Item 19. The method according to item 19, characterized in that the ALF filter is a CCALF filter for cross-component adaptive loop filtering. [Item 21] 20. The method according to item 19, wherein the image block level is a coding tree unit (CTU) level. [Item 22] Parsing the first identifier and the second identifier from the codestream, each corresponding to two chromaticity components of the current image, includes: contextually analyzing first identifiers from the codestream, each corresponding to two chrominance components of a current image; 20. The method of claim 19, further comprising: parsing second identifiers from the codestream in a truncated unary manner, the second identifiers corresponding to two chromaticity components of the current image, respectively. [Item 23] Item 20. The method of item 19, wherein in the codestream, for the two chrominance components, different identifiers are used in image-level syntax elements to indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF or not. [Item 24] Item 20. The method of claim 19, wherein in the codestream, for the two chrominance components, different identifiers are used in slice-level syntax elements to indicate whether the corresponding chrominance component is filtered by the adaptive loop filter ALF or not. [Item 25] A video encoding device, comprising: a memory and a processor; the memory is for storing a program, The processor calls the program, and when the program is executed, obtaining color components of an image sequence, the color components including two chromaticity components; filtering reconstructed blocks of color components of at least some images of said image sequence with an adaptive loop filter technique; generating a codestream for the image sequence, wherein in the codestream, for the two chrominance components, different identifiers in image level syntax elements are used to indicate whether the corresponding chrominance component has been filtered by an adaptive loop filter (ALF). [Item 26] Item 26. The device described in Item 25, characterized in that in the codestream, for the two chrominance components, different identifiers are used in slice-level syntax elements to indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF or not. [Item 27] Item 26. The device described in Item 25, characterized in that in the codestream, for each chrominance component of the two chrominance components, in an image block level syntax element of the codestream, a first identifier indicates whether the chrominance component has been filtered with ALF, and if the first identifier indicates that the chrominance component has been filtered with ALF, a second identifier indicates the ALF filter used for the chrominance component. [Item 28] Item 28. The device according to item 27, characterized in that the ALF filter is a CCALF filter for cross-component adaptive loop filtering. [Item 29] Item 28. The device according to item 27, characterized in that the image block level is a coding tree unit (CTU) level. [Item 30] the first identifier is coded in a contextual manner; 28. The apparatus according to claim 27, wherein the second identifier is at least one of encoded in a truncated unary format. [Item 31] A video decoding device, comprising: a memory and a processor; the memory is for storing a program, The processor calls the program, and when the program is executed, obtaining a codestream of an image sequence, wherein an image of the image sequence includes two chrominance components, and in the codestream, for the two chrominance components, using different identifiers in image-level syntax elements to respectively indicate whether the corresponding chrominance component is ALF filtered; parsing from said codestream identifiers corresponding respectively to two chrominance components of the current image; determining whether to filter the reconstructed blocks of the two chrominance components of the current image using ALF based on identifiers corresponding to the two chrominance components, respectively. [Item 32] Item 32. The device of item 31, wherein in the codestream, for the two chrominance components, different identifiers are used in slice-level syntax elements to indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF or not. [Item 33] Item 32. The device described in Item 31, characterized in that in the codestream, for each chrominance component of the two chrominance components, a first identifier indicates whether the chrominance component has been filtered with ALF in an image block level syntax element of the codestream, and if the first identifier indicates that the chrominance component has been filtered with ALF, a second identifier indicates the ALF filter used for the chrominance component. [Item 34] Item 34. The device according to item 33, characterized in that the ALF filter is a CCALF filter for cross-component adaptive loop filtering. [Item 35] When analyzing the identifiers respectively corresponding to the two chromaticity components of the current image from the codestream, the processor specifically: contextually analyzing first identifiers from the codestream, each corresponding to two chrominance components of a current image; and Item 34. The device according to item 33, characterized in that it is used for at least one of parsing second identifiers from the codestream in a truncated unary manner, each of which corresponds to two chromaticity components of the current image. [Item 36] Item 34. The device according to item 33, characterized in that the image block level is a coding tree unit (CTU) level. [Item 37] A video encoding device, comprising: a memory and a processor; the memory is for storing a program, The processor calls the program, and when the program is executed, obtaining color components of an image sequence, the color components including two chromaticity components; filtering reconstructed blocks of color components of at least some images of the image sequence with ALF; 1. A video encoding device for generating a codestream for the image sequence, the video encoding device being configured to perform the following operations: for each chrominance component of the two chrominance components, indicate with a first identifier whether the chrominance component has been filtered with ALF, and if the first identifier indicates that the chrominance component has been filtered with ALF, indicate with a second identifier the ALF filter used for the chrominance component. [Item 38] Item 38. The device according to item 37, characterized in that the ALF filter is a CCALF filter for cross-component adaptive loop filtering. [Item 39] Item 38. The device according to item 37, characterized in that the image block level is a coding tree unit (CTU) level. [Item 40] the first identifier is coded in a contextual manner; Item 38. The apparatus according to item 37, wherein the second identifier is at least one of encoded in a truncated unary format. [Item 41] Item 38. The device described in Item 37, characterized in that in the codestream, for the two chrominance components, different identifiers are used in image-level syntax elements to indicate whether the corresponding chrominance component has been filtered by the adaptive loop filter ALF. [Item 42] Item 38. The device of item 37, wherein in the codestream, for the two chrominance components, different identifiers are used in slice-level syntax elements to indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF or not. [Item 43] A video decoding device, comprising: a memory and a processor; the memory is for storing a program, The processor calls the program, and when the program is executed, obtaining a codestream of an image sequence, wherein an image of the image sequence includes two chrominance components, and for each chrominance component of the two chrominance components, an image block level syntax element of the codestream indicates whether the chrominance component is ALF filtered by a first identifier and indicates the ALF filter used for the chrominance component by a second identifier; parsing the first and second identifiers from the codestream, which correspond respectively to two chrominance components of the current image; 1. A video decoding device characterized in that the video decoding device is configured to perform the following operations: for each chrominance component of a current image block, determining whether or not to filter a reconstructed block of the chrominance component using ALF based on the first identifier corresponding to the chrominance component; and if it is decided to use ALF, determining to filter the reconstructed block of the chrominance component with the corresponding ALF filter based on the second identifier. [Item 44] Item 44. The device according to item 43, characterized in that the ALF filter is a CCALF filter for cross-component adaptive loop filtering. [Item 45] Item 44. The device according to item 43, characterized in that the image block level is a coding tree unit (CTU) level. [Item 46] When analyzing the first identifier and the second identifier, which respectively correspond to two chromaticity components of the current image from the codestream, the processor specifically: contextually analyzing first identifiers from the codestream, each corresponding to two chrominance components of a current image; Item 44. The device according to item 43, characterized in that it is used for parsing second identifiers from the codestream in a truncated unary manner, the second identifiers corresponding respectively to two chromaticity components of the current image. [Item 47] Item 44. The device of item 43, wherein in the codestream, for the two chrominance components, different identifiers are used in image-level syntax elements to indicate whether the corresponding chrominance component has been filtered by the adaptive loop filter ALF. [Item 48] Item 44. The device of item 43, wherein in the codestream, for the two chrominance components, different identifiers are used in slice-level syntax elements to indicate whether the corresponding chrominance components are filtered by the adaptive loop filter ALF or not. [Item 49] A computer-readable storage medium having a computer program stored thereon, the computer program being characterized in that, when executed by a processor, it implements the method according to any one of items 1 to 24.

Claims

1. In a video encoding method, 1. A video coding method comprising: encoding an image to generate a bitstream, wherein in the bitstream, a first syntax element is configured to indicate whether a first chrominance component is filtered with an adaptive loop filter (ALF), and a second syntax element is configured to indicate whether a second chrominance component is filtered with the ALF.

2. 2. The video coding method of claim 1, wherein the adaptive loop filter (ALF) is different from a cross-component adaptive loop filter (CC-ALF).

3. 2. The video encoding method of claim 1, wherein generating the bitstream comprises filtering a luma component and the first and second chroma components of the image with the ALF; and further filtering the first and second chroma components with a cross-component adaptive loop filter (CC-ALF) different from the ALF.

4. 2. The video encoding method of claim 1, wherein in the bitstream, for each of the first chrominance component and the second chrominance component, a first identifier is configured in a corresponding syntax element at an image block level in the bitstream to indicate whether the first chrominance component is filtered with the ALF, and in response to the first identifier indicating that the first chrominance component is filtered using the ALF, a second identifier is configured to indicate the ALF used for the second chrominance component.

5. The video encoding method of claim 4 , wherein the image block level is a coding tree unit (CTU) level.

6. The video encoding method of claim 4 , wherein the first identifier is encoded in a context manner.

7. The video encoding method of claim 4 , wherein the second identifier is encoded in a truncated unary format.

8. 2. The video encoding method of claim 1, wherein, in the bitstream, in response to the first syntax element indicating that the first chrominance component is to be filtered with the ALF, a first identifier is configured to indicate that the ALF is used by the first chrominance component; or, in response to the second syntax element in the bitstream indicating that the second chrominance component is to be filtered with the ALF, a second identifier is configured to indicate that the ALF is used by the second chrominance component.

9. In a video decoding method, obtaining a bitstream of an image, the image including a first chrominance component and a second chrominance component, a first syntax element configured to indicate whether the first chrominance component is filtered with an adaptive loop filter (ALF), and a second syntax element configured to indicate whether the second chrominance component is filtered with the ALF; parsing the bitstream to obtain the first syntax element and the second syntax element; determining whether the first chrominance component and the second chrominance component of the image are filtered by the ALF according to the first syntax element and the second syntax element, wherein the ALF is different from a cross-component adaptive loop filter (CC-ALF); A video decoding method comprising:

10. In a bitstream generation method, obtaining color components of an image, the color components including a first chromaticity component and a second chromaticity component; generating a bitstream of the image, wherein a first syntax element is configured to indicate whether the first chrominance component is filtered with an adaptive loop filter (ALF), and a second syntax element is configured to indicate whether the second chrominance component is filtered with the ALF; A bitstream generation method comprising:

Images