Method and apparatus for chrominance quantization parameter signaling

Abstract

To provide a method and apparatus for signaling of chrominance quantization parameters.SOLUTION: A method for inverse quantization of a current block of a picture, the method comprising: receiving a bitstream; obtaining a joint chrominance component residual (JCCR) control flag from the bitstream; obtaining chrominance mapping information from the bitstream based on the JCCR control flag; obtaining at least one chrominance quantization parameter (QP) offset from the bitstream based on the JCCR control flag; and performing, based on the obtained chrominance mapping information and the at least one obtained chrominance QP offset: The method includes obtaining a QP value for a current chrominance block, and performing dequantization on the current chrominance block using the determined QP value.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This patent application claims priority from International Patent Application PCT / RU2019 / 000664, filed September 23, 2019. The entire disclosure of the above patent application is incorporated by reference.

[0002] [Technical field] FIELD Embodiments of the present disclosure relate generally to the field of picture processing, and more particularly to a method and apparatus for signaling chrominance quantization parameters. [Background technology]

[0003] Video coding (video encoding and / or decoding) is used in a wide range of digital video applications, such as broadcast digital TV, video transmission over the Internet and mobile networks, real-time conversation applications such as video chat, video conferencing, DVD and Blu-ray discs, video content acquisition and editing systems, and camcorders in security applications.

[0004] The amount of video data required to render even a relatively short video can be substantial, which can create difficulties when the data is streamed or communicated across communication networks with limited bandwidth capacity. Therefore, video data is typically compressed before being communicated across modern telecommunications networks. Video size can also be an issue when the video is stored on a storage device, as memory resources may be limited. Video compression devices often use software and / or hardware at the source to code the video data before transmission or storage, thereby reducing the amount of data needed to represent a digital video image. The compressed data is then received at the destination by a video decompression device, which decodes the video data. Due to limited network resources and ever-increasing demands for higher video quality, compression and decompression techniques that improve compression ratios with little or no sacrifice in picture quality are desirable. Summary of the Invention

[0005] Embodiments of the present application provide apparatuses and methods for encoding and decoding according to the independent claims.

[0006] These and other objects are achieved by the subject matter of the independent claims. Further realisation forms are evident from the dependent claims, the description and the drawings.

[0007] The present disclosure provides the following: 1. A method for inverse quantization of a current block of a picture, the method being performed by a decoder, the method comprising: receiving a bitstream; obtaining a joint chrominance component residual (JCCR) control flag from the bitstream; obtaining chrominance mapping information from the bitstream based on a JCCR control flag; obtaining at least one chrominance quantization parameter (QP) offset from the bitstream based on a JCCR control flag; obtaining a QP value for the current chrominance block based on the obtained chrominance mapping information and the at least one obtained chrominance QP offset; performing inverse quantization on the current chrominance block using the determined QP value; A method comprising:

[0008] Here, signaling of PPS and slice header QP offsets for chrominance components for JCCR mode, as well as signaling of SPS chrominance mapping information for JCCR coding mode, is performed.

[0009] Depending on the SPS JCCR control flag, the signaling / decoding of the joint chrominance component residual offset is performed. Due to the conditional signaling of the joint chrominance component residual offset, less information needs to be signaled, thus saving resources.

[0010] In the above method, the bitstream may include an SPS level syntax, and the JCCR control flag may be obtained from the SPS level syntax.

[0011] In the above method, the JCCR control flag may be sps_joint_cbcr_enabled_flag.

[0012] where sps_joint_cbcr_enabled_flag specifies whether joint coding of chroma residual is enabled, where sps_joint_cbcr_enabled_flag equal to 1 specifies that joint coding of chroma residual is enabled for a coded layer video sequence (CLVS), sps_joint_cbcr_enabled_flag equal to 0 specifies that joint coding of chroma residual is disabled for a coded layer video sequence, and when not present, the value of sps_joint_cbcr_enabled_flag is inferred to be equal to 0.

[0013] In the above method, if the value of sps_joint_cbcr_enabled_flag is 1, at least one obtained chrominance QP offset may be specified by slice_joint_cbcr_qp_offset, where slice_joint_cbcr_qp_offset may be present in the slice header syntax and specifies the difference to be added to the value of pps_joint_cbcr_qp_offset_value when determining the value of Qp'CbCr. The value of slice_joint_cbcr_qp_offset shall be in the range of -12 to +12 inclusive. When slice_joint_cbcr_qp_offset is not present, it is inferred to be equal to 0. The value of pps_joint_cbcr_qp_offset_value + slice_joint_cbcr_qp_offset shall be in the range of -12 to +12 inclusive.

[0014] Here, the flag slice_joint_cbcr_qp_offset may also be expressed as sh_joint_cbcr_qp_offset.

[0015] In the above method, the chrominance mapping information may include delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and the chrominance mapping information may be obtained from the SPS level syntax included in the bitstream.

[0016] where sps_delta_qp_in_val_minus1[i][j] specifies the delta value used to derive the input coordinate of the jth pivot point of the ith chroma QP mapping table, and when not present, the value of sps_delta_qp_in_val_minus1[0][j] is inferred to be equal to 0, where i and j are integer values. Here, delta_qp_out_val[i][j] specifies the delta value used to derive the output coordinate of the jth pivot point of the ith chroma QP mapping table. When delta_qp_out_val[0][j] is not present in the bitstream, the value of delta_qp_out_val[0][j] is inferred to be equal to 0. Here, delta_qp_out_val may also be denoted as sps_delta_qp_diff_val.

[0017] In the above method, the SPS level syntax may include the following structure: [Table 1]

[0018] Therefore, signaling of PPS and slice header QP offsets for chrominance components for JCCR modes, as well as signaling of SPS chrominance mapping information for JCCR coding modes, may be performed depending on the SPS JCCR control flag according to the above table. For example, the sps JCCR control flag is sps_joint_cbcr_enabled_flag, which is signaled in an SPS level syntax, e.g., seq_parameter_set_rbsp syntax. In particular, it can be appreciated that the value of index "i" is determined based on the value of sps_joint_cbcr_enabled_flag, and thus, redundant signaling of JCCR syntax elements can be avoided when the JCCR tool is disabled. The signaling / decoding of pps_joint_cbcr_qp_offset depends on sps_joint_cbcr_enabled_flag, i.e., it can be recognized that pps_joint_cbcr_qp_offset is signaled or can be decoded only when the value of sps_joint_cbcr_enabled_flag is true (e.g., 1). Due to the conditional signaling of pps_joint_cbcr_qp_offset, less information needs to be signaled, thus saving resources.

[0019] where seq_parameter_set_rbsp indicates the Raw Byte Sequence Payload (RBSP) syntax of the sequence parameter set, sps_num_points_in_qp_table_minus1[i] plus 1 specifies the number of points used to describe the i-th chroma QP mapping table, the value of sps_num_points_in_qp_table_minus1[i] ranges from 0 to 36, and when not present, the value of sps_num_points_in_qp_table_minus1[0] is inferred to be equal to 0.

[0020] In the above method, obtaining at least one chrominance QP offset from the bitstream based on the JCCR control flag may include obtaining at least one chrominance QP offset from a picture parameter set (PPS) level syntax of the bitstream based on the JCCR control flag.

[0021] In the above method, the PPS level syntax may include the following structure: [Table 2]

[0022] where pic_parameter_set_rbsp indicates picture parameter set RBSP syntax, pps_cb_qp_offset and pps_cr_qp_offset specify offsets to the luma quantization parameter Qp'Y used to derive Qp'Cb and Qp'Cr, respectively, the values ​​of pps_cb_qp_offset and pps_cr_qp_offset are in the range of -12 to +12, when sps_croma_format_idc is equal to 0, pps_cb_qp_offset and pps_cr_qp_offset are not used in the decoding process and the decoder shall ignore these values, when not present, the values ​​of pps_cb_qp_offset and pps_cr_qp_offset are inferred to be equal to 0, and sps_joint_cbcr_enabled_flag equal to 1 indicates that joint coding of chroma residuals is enabled for coded layer video sequences (CLVS, coded layer video sequences). sequence), sps_joint_cbcr_enabled_flag equal to 0 specifies that joint coding of chroma residual is disabled for CLVS, and when not present, the value of sps_joint_cbcr_enabled_flag is inferred to be equal to 0. pps_joint_cbcr_qp_offset_value specifies the offset to the luma quantization parameter Qp'Y used to derive Qp'CbCr, and the value of pps_joint_cbcr_qp_offset_value is in the range of -12 to +12, inclusive.

[0023] The present disclosure further provides a method for inverse quantization of a current block of a picture, the method being performed by a decoder, the method comprising: receiving a bitstream, the bitstream including a slice header syntax and a PPS syntax; obtaining a syntax element from a PPS syntax, the obtained syntax element including at least one chrominance quantization parameter (QP) offset; obtaining chrominance QP offset information from a slice header, the QP offset information being obtained independently from any PPS syntax element in the PPS syntax; determining a QP value for the current chrominance block depending on at least one chrominance QP offset obtained from the PPS syntax and chrominance QP offset information obtained from the slice header syntax; performing inverse quantization on the current chrominance block using the determined QP value; Includes.

[0024] Therefore, the signaling of the PPS and slice header QP offsets for the chrominance components is performed independently of each other according to the above table. Instead, previously, the flag pps_slice_chroma_qp_offsets_present_flag was signaled in the PPS level syntax, which controlled whether there were any further offsets signaled in the slice header; that is, on the decoder side, the decoder needs to check the value of pps_slice_chroma_qp_offsets_present_flag to determine whether there were any further offsets signaled in the slice header. Compared to the previous method, now, in the above method, the flag pps_slice_chroma_qp_offsets_present_flag is no longer signaled. In other words, there is always an offset signaled in the slice header, and therefore the decoder knows that there is a further offset signaled in the slice header without checking the value of pps_slice_chroma_qp_offsets_present_flag, in other words, both the PPS level syntax and the slice header syntax always contain the offsets, so decoding / signaling of chrominance QP offsets in the slice header becomes easier.

[0025] In the above method, the at least one chrominance QP offset obtained from the PPS syntax may include pps_cb_qp_offset, pps_cr_qp_offset, pps_joint_cbcr_qp_offset, and cu_chroma_qp_offset_enabled_flag.

[0026] In the above method, when the value of cu_chroma_qp_offset_enabled_flag is 1, the at least one chrominance QP offset obtained from the PPS syntax may further include cu_chroma_qp_offset_subdiv, chroma_qp_offset_list_len_minus1, cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i];

number

[0027] In the above method, the chrominance QP offset information obtained from the slice header syntax may include slice_cb_qp_offset and slice_cr_qp_offset.

[0028] In the above method, if the value of sps_joint_cbcr_enabled_flag included in the bitstream is 1, the chrominance QP offset information obtained from the slice header syntax may further include slice_joint_cbcr_qp_offset.

[0029] In the above method, the PPS syntax may include the following structure: [Table 3]

[0030] In the above method, the slice header syntax may include the following structure: [Table 4]

[0031] In the above method, the flag pps_slice_chroma_qp_offsets_present_flag may be omitted in the PPS syntax, or The slice header and PPS syntax may always include at least one element related to a chrominance QP offset.

[0032] The present disclosure further provides a method for inverse quantization of a current block of a picture, the method being performed by an encoder, the method comprising: encoding a joint chrominance component residual (JCCR) control flag into the bitstream; encoding chrominance mapping information into the bitstream based on the JCCR control flag; encoding at least one chrominance quantization parameter (QP) offset into the bitstream based on the JCCR control flag; providing a bitstream; Includes.

[0033] In the above method, the bitstream may include an SPS level syntax, and the JCCR control flag is encoded into the SPS level syntax.

[0034] In the above method, the JCCR control flag may be sps_joint_cbcr_enabled_flag.

[0035] In the above method, if the value of sps_joint_cbcr_enabled_flag is 1, at least one coded chrominance QP offset may be specified by slice_joint_cbcr_qp_offset.

[0036] In the above method, the chrominance mapping information may include delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and the chrominance mapping information may be encoded into the SPS level syntax included in the bitstream.

[0037] In the above method, the SPS level syntax may include the following structure: [Table 5]

[0038] where same_qp_table_for_chroma indicates how many chroma QP mapping tables are signaled. When same_qp_table_for_chroma is equal to 1, it specifies that only one chroma QP mapping table is signaled, and this table is applied to the Cb and Cr residuals, and also to the joint Cb-Cr residual when sps_joint_cbcr_enabled_flag is equal to 1. same_qp_table_for_chroma equal to 0 specifies that two chroma QP mapping tables are signaled in the SPS: two for Cb and Cr, and one more for the joint Cb-Cr when sps_joint_cbcr_enabled_flag is equal to 1. When same_qp_table_for_chroma is not present in the bitstream, the value of same_qp_table_for_chroma is inferred to be equal to 1.

[0039] where num_points_in_qp_table_minus1[i] plus 1 specifies the number of points used to describe the ith chroma QP mapping table. The value of num_points_in_qp_table_minus1[i] shall be in the range from 0 to 63 + QpBdOffset, inclusive. When num_points_in_qp_table_minus1[0] is not present in the bitstream, the value of num_points_in_qp_table_minus1[0] is inferred to be equal to 0.

[0040] In the above method, the step of encoding at least one chrominance QP offset into the bitstream based on the JCCR control flag comprises: The method may include encoding at least one chrominance QP offset into a picture parameter set (PPS) level syntax of the bitstream based on the JCCR control flag.

[0041] In the above method, the PPS level syntax may include the following structure: [Table 6]

[0042] The present disclosure may further provide a method for inverse quantization of a current block of a picture, the method being performed by an encoder, the method comprising: encoding syntax elements from a slice header and PPS syntax into a bitstream, the syntax elements including at least one chrominance quantization parameter (QP) offset; encoding chrominance QP offset information from a slice header into a bitstream, where the QP offset information is obtained independently from any PPS syntax element in the PPS syntax; providing a bitstream; Includes.

[0043] In the above method, the at least one chrominance QP offset encoded from the PPS syntax may include pps_cb_qp_offset, pps_cr_qp_offset, pps_joint_cbcr_qp_offset, and cu_chroma_qp_offset_enabled_flag.

[0044] In the above method, when the value of cu_chroma_qp_offset_enabled_flag is 1, the at least one chrominance QP offset encoded from the PPS syntax may further include cu_chroma_qp_offset_subdiv, chroma_qp_offset_list_len_minus1, cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i];

number

[0045] In the above method, the chrominance QP offset information coded from the slice header syntax may include slice_cb_qp_offset and slice_cr_qp_offset.

[0046] In the above method, if the value of sps_joint_cbcr_enabled_flag included in the bitstream is 1, the chrominance QP offset information coded from the slice header syntax may further include slice_joint_cbcr_qp_offset.

[0047] In the above method, the PPS syntax may include the following structure: [Table 7]

[0048] In the above method, the slice header syntax may include the following structure: [Table 8]

[0049] In the above method, the flag pps_slice_chroma_qp_offsets_present_flag may be omitted in the PPS syntax, or The slice header and PPS syntax may always include at least one element related to a chrominance QP offset.

[0050] The present disclosure further provides a decoder including processing circuitry for performing the method according to the above method.

[0051] The present disclosure further provides an encoder including processing circuitry for performing the above method.

[0052] The present disclosure also provides a computer program product comprising program code for performing the above method when executed on a computer or processor.

[0053] The present disclosure further provides a decoder including one or more processors and a non-transitory computer-readable storage medium coupled to the processors and storing programming for execution by the processors, the programming, when executed by the processors, configuring the decoder to perform the above-described method.

[0054] The present disclosure further provides an encoder including one or more processors and a non-transitory computer-readable storage medium coupled to the processors and storing programming for execution by the processors, the programming, when executed by the processors, configuring the encoder to perform the above-described method.

[0055] The present disclosure further provides a non-transitory computer readable medium carrying program code that, when executed by a computing device, causes the computing device to perform the above-described method.

[0056] The present disclosure further provides a decoder including: a receiving unit configured to receive a bitstream; a first acquisition unit configured to acquire a joint chrominance component residual (JCCR) control flag from the bitstream; a second acquisition unit configured to acquire chrominance mapping information from the bitstream based on the JCCR control flag; a third acquisition unit configured to acquire at least one chrominance quantization parameter (QP) offset from the bitstream based on the JCCR control flag; a fourth acquisition unit configured to acquire a QP value for a current chrominance block based on the acquired chrominance mapping information and the at least one acquired chrominance QP offset; and an inverse quantization unit configured to perform inverse quantization on the current chrominance block by using the determined QP value.

[0057] In the above decoder, the bitstream may include an SPS level syntax, and the JCCR control flag may be obtained from the SPS level syntax.

[0058] In the above decoder, the JCCR control flag may be sps_joint_cbcr_enabled_flag.

[0059] In the above decoder, if the value of sps_joint_cbcr_enabled_flag is 1, at least one obtained chrominance QP offset may be specified by slice_joint_cbcr_qp_offset.

[0060] In the above decoder, the chrominance mapping information may include delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and the chrominance mapping information may be obtained from the SPS level syntax included in the bitstream.

[0061] In the above decoder, the SPS level syntax may include the following structure: [Table 9]

[0062] In the decoder, obtaining at least one chrominance QP offset from the bitstream based on the JCCR control flag may include obtaining the at least one chrominance QP offset from a picture parameter set (PPS) level syntax of the bitstream based on the JCCR control flag.

[0063] In the above decoder, the PPS level syntax may include the following structure: [Table 10]

[0064] The present disclosure further provides a decoder including: a receiving unit configured to receive a bitstream, the bitstream including a slice header syntax and a PPS syntax; a first acquisition unit configured to acquire syntax elements from the PPS syntax, the acquired syntax elements including a chrominance quantization parameter (QP) offset; a second acquisition unit configured to acquire chrominance QP offset information from the slice header, the QP offset information being acquired independently from any PPS syntax element in the PPS syntax; a determination unit configured to determine a QP value for a current chrominance block depending on the chrominance QP offset obtained from the PPS syntax and the chrominance QP offset information obtained from the slice header syntax; and an inverse quantization unit configured to perform inverse quantization on the current chrominance block by using the determined QP value.

[0065] In the above decoder, the at least one chrominance QP offset obtained from the PPS syntax may include pps_cb_qp_offset, pps_cr_qp_offset, pps_joint_cbcr_qp_offset, and cu_chroma_qp_offset_enabled_flag.

[0066] In the decoder above, when the value of cu_chroma_qp_offset_enabled_flag is 1, the at least one chrominance QP offset obtained from the PPS syntax may further include cu_chroma_qp_offset_subdiv, chroma_qp_offset_list_len_minus1, cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i];

number

[0067] In the above decoder, the chrominance QP offset information obtained from the slice header syntax may include slice_cb_qp_offset and slice_cr_qp_offset.

[0068] In the above decoder, if the value of sps_joint_cbcr_enabled_flag included in the bitstream is 1, the chrominance QP offset information obtained from the slice header syntax may further include slice_joint_cbcr_qp_offset.

[0069] In the above decoder, the PPS syntax may include the following structure: [Table 11]

[0070] In the above decoder, the slice header syntax may include the following structure: [Table 12]

[0071] In the above decoder, the flag pps_slice_chroma_qp_offsets_present_flag may be omitted in the PPS syntax, or The slice header and PPS syntax may always include at least one element related to a chrominance QP offset.

[0072] The present disclosure further provides an encoder including a first encoding unit configured to encode a joint chrominance component residual (JCCR) control flag into a bitstream; a second encoding unit configured to encode chrominance mapping information into the bitstream based on the JCCR control flag; a third encoding unit configured to encode at least one chrominance quantization parameter (QP) offset into the bitstream based on the JCCR control flag; and a providing unit configured to provide the bitstream.

[0073] In the above encoder, the bitstream may include an SPS level syntax, and the JCCR control flag may be obtained from the SPS level syntax.

[0074] In the above encoder, the JCCR control flag may be sps_joint_cbcr_enabled_flag.

[0075] In the above encoder, if the value of sps_joint_cbcr_enabled_flag is 1, at least one obtained chrominance QP offset may be specified by slice_joint_cbcr_qp_offset.

[0076] In the above encoder, the chrominance mapping information may include delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and the chrominance mapping information may be obtained from the SPS level syntax included in the bitstream.

[0077] In the above encoder, the SPS level syntax may include the following structure: [Table 13]

[0078] In the above encoder, obtaining at least one chrominance QP offset from the bitstream based on the JCCR control flag may include obtaining the at least one chrominance QP offset from a picture parameter set (PPS) level syntax of the bitstream based on the JCCR control flag.

[0079] In the above encoder, the PPS level syntax may include the following structure: [Table 14]

[0080] The present disclosure further provides an encoder including: a first encoding unit configured to encode syntax elements from a slice header and a PPS syntax into a bitstream, the syntax elements including a chrominance quantization parameter (QP) offset; a second encoding unit configured to encode chrominance QP offset information from the slice header into the bitstream, the QP offset information being obtained independently from any PPS syntax elements in the PPS syntax; and a providing unit configured to provide the bitstream.

[0081] In the above encoder, the at least one chrominance QP offset obtained from the PPS syntax may include pps_cb_qp_offset, pps_cr_qp_offset, pps_joint_cbcr_qp_offset, and cu_chroma_qp_offset_enabled_flag.

[0082] In the above encoder, when the value of cu_chroma_qp_offset_enabled_flag is 1, the at least one chrominance QP offset obtained from the PPS syntax may further include cu_chroma_qp_offset_subdiv, chroma_qp_offset_list_len_minus1, cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i];

number

[0083] In the above encoder, the chrominance QP offset information obtained from the slice header syntax may include slice_cb_qp_offset and slice_cr_qp_offset.

[0084] In the above encoder, when the value of sps_joint_cbcr_enabled_flag included in the bitstream is 1, the chrominance QP offset information obtained from the slice header syntax may further include slice_joint_cbcr_qp_offset.

[0085] In the above encoder, the PPS syntax may include the following structure: [Table 15]

[0086] In the above encoder, the slice header syntax may include the following structure: [Table 16]

[0087] In the above encoder, the flag pps_slice_chroma_qp_offsets_present_flag may be omitted in the PPS syntax, or The slice header and PPS syntax may always include at least one element related to a chrominance QP offset.

[0088] The details of one or more embodiments are set forth in the accompanying drawings and the detailed description below. Other features, objects, and advantages will become apparent from the detailed description, the drawings, and the claims. [Brief explanation of the drawings]

[0089] In the following, embodiments of the invention will be described in more detail with reference to the accompanying figures and drawings. [Figure 1A] 1 is a block diagram illustrating an example of a video coding system configured to implement embodiments of the present invention. [Figure 1B] FIG. 2 is a block diagram illustrating another example of a video coding system configured to implement embodiments of the present invention. [Figure 2] 1 is a block diagram illustrating an example of a video encoder configured to implement embodiments of the present invention; [Figure 3] 1 is a block diagram illustrating an exemplary structure of a video decoder configured to implement embodiments of the present invention. [Figure 4] FIG. 1 is a block diagram illustrating an example of an encoding device or a decoding device. [Figure 5] FIG. 10 is a block diagram showing another example of an encoding device or a decoding device. [Figure 6] 31 is a block diagram illustrating an exemplary structure of a content supply system 3100 for implementing a content distribution service. [Figure 7] FIG. 2 is a block diagram illustrating the structure of an example terminal device. [Figure 8] 1 shows a flowchart of a method for inverse quantization of a current block of a picture, the method being performed by a decoder, according to an embodiment of the present disclosure. [Figure 9] 10 shows a flowchart of a method for inverse quantization of a current block of a picture according to a further embodiment of the present disclosure, the method being performed by a decoder. [Figure 10] 1 shows a flowchart of a method for inverse quantization of a current block of a picture, the method being performed by an encoder, according to an embodiment of the present disclosure. [Figure 11] 1 shows a flowchart of a method for inverse quantization of a current block of a picture according to the present disclosure, the method being performed by an encoder. [Figure 12] 1 illustrates a decoder according to an embodiment of the present disclosure. [Figure 13] 1 illustrates a decoder according to another embodiment of the present disclosure. [Figure 14] 1 illustrates an encoder according to an embodiment of the present disclosure. [Figure 15] 1 illustrates an encoder according to another embodiment of the present disclosure.

[0090] In the following, identical reference signs, unless expressly specified otherwise, denote identical or at least functionally equivalent features. DETAILED DESCRIPTION OF THE INVENTION

[0091] In the following description, reference is made to the accompanying drawings which form a part of this disclosure and which show, by way of illustration, specific aspects of embodiments of the invention or in which embodiments of the invention may be used. It is understood that embodiments of the invention may be used in other ways and may include structural or logical changes not shown in the drawings. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0092] For example, it is understood that disclosure related to a described method may also apply to a corresponding device or system configured to perform the method, and vice versa. For example, when one or more particular method steps are described, a corresponding device may include one or more units, e.g., functional units, for performing the described one or more method steps, even if such one or more units are not explicitly described or shown in the drawings (e.g., one unit performs one or more steps, or multiple units each perform one or more of the steps). On the other hand, for example, when a particular apparatus is described based on one or more units, e.g., functional units, a corresponding method may include a step for performing the function of one or more units, even if such one or more steps are not explicitly described or shown in the drawings (e.g., one step performs the function of one or more units, or multiple steps each perform the function of one or more of the units). Furthermore, it is understood that features of various exemplary embodiments and / or aspects described herein may be combined with each other, unless otherwise specified.

[0093] Typically, video coding refers to the processing of a sequence of pictures forming a video or a video sequence. Instead of the term "picture," the terms "frame" or "image" may be used synonymously in the field of video coding. Video coding (or coding in general) includes two parts: video encoding and video decoding. Video encoding is performed on the source side and typically involves processing the original video picture (e.g., by compression) to reduce the amount of data needed to represent the video picture (for more efficient storage and / or transmission). Video decoding is performed on the destination side and typically involves the reverse processing compared to the encoder to reconstruct the video picture. Embodiments referring to "coding" of a video picture (or pictures in general) shall be understood to relate to "encoding" or "decoding" of the video picture or the respective video sequence. The combination of the encoder and decoder is also called a CODEC (Coding and Decoding).

[0094] In the case of lossless video coding, the original video picture can be reconstructed, i.e., the reconstructed video picture has the same quality as the original video picture (assuming there is no transmission loss or other data loss during storage or transmission). In the case of lossy video coding, further compression, e.g., by quantization, is performed to reduce the amount of data representing the video picture, which cannot be fully reconstructed at the decoder, i.e., the quality of the reconstructed video picture is low or poor compared to the quality of the original video picture.

[0095] Some video coding standards belong to the group of "lossy hybrid video codecs" (i.e., they combine spatial and temporal prediction in the sample domain with 2D transform coding to apply quantization in the transform domain). Each picture of a video sequence is typically partitioned into a set of non-overlapping blocks, and coding is typically performed at the block level. In other words, at an encoder, video is typically processed, i.e., encoded, at the block (video block) level, for example, by generating a predictive block using spatial (intra-picture) prediction and / or temporal (inter-picture) prediction, subtracting the predictive block from a current block (the block currently being processed / to be processed) to obtain a residual block, transforming the residual block, and quantizing the residual block in the transform domain to reduce the amount of data to be transmitted (compression). Meanwhile, at a decoder, an inverse process compared to the encoder is applied to the coded or compressed block to reconstruct the current block for representation. Furthermore, the encoder replicates the decoder processing loop, so that both generate the same predictions (e.g., intra- and inter-predictions) and / or reconstructions for processing, i.e., coding, subsequent blocks.

[0096] Hereinafter, embodiments of a video coding system 10, a video encoder 20, and a video decoder 30 will be described with reference to FIGS.

[0097] 1A is a schematic block diagram illustrating an example coding system 10, e.g., video coding system 10 (or coding system 10 for short), that may utilize the techniques of the present application. A video encoder 20 (or encoder 20 for short) and a video decoder 30 (or decoder 30 for short) of video coding system 10 represent examples of devices that may be configured to perform techniques according to various examples described herein.

[0098] As shown in FIG. 1A, coding system 10 includes a source device 12 configured to provide encoded picture data 21 to, for example, a destination device 14 for decoding encoded picture data 13.

[0099] Source device 12 includes an encoder 20 and may further, i.e. optionally, include a picture source 16 , a pre-processor (or pre-processing unit) 18 , for example a picture pre-processor 18 , and a communication interface or unit 22 .

[0100] Picture source 16 may be or include any kind of picture capture device, e.g., a camera for capturing real-world pictures, and / or any kind of picture generation device, e.g., a computer graphics processor for generating computer-animated pictures, or any kind of other device for obtaining and / or providing real-world pictures, computer-generated pictures (e.g., screen content, virtual reality (VR) pictures), and / or any combination thereof (e.g., augmented reality (AR) pictures). Picture source may also be any kind of memory or storage for storing any of the above pictures.

[0101] In contrast to the pre-processor 18 and the processing performed by the pre-processing unit 18 , the pictures or picture data 17 may also be referred to as raw pictures or raw picture data 17 .

[0102] The pre-processor 18 is configured to receive (raw) picture data 17 and perform pre-processing on the picture data 17 to obtain a pre-processed picture 19 or pre-processed picture data 19. The pre-processing performed by the pre-processor 18 may include, for example, cropping, color format conversion (e.g., from RGB to YCbCr), color correction or noise removal. It will be understood that the pre-processing unit 18 may be an optional component.

[0103] Video encoder 20 is configured to receive pre-processed picture data 19 and provide encoded picture data 21 (further details are described below, eg, with reference to FIG. 2).

[0104] The communication interface 22 of the source device 12 may be configured to receive the encoded picture data 21 and transmit the encoded picture data 21 (or any further processed version thereof) over the communication channel 13 to another device, such as the destination device 14 or any other device, for storage or direct reconstruction.

[0105] The destination device 14 includes a decoder 30 (e.g., a video decoder 30), and may further, i.e. optionally, include a communication interface or communication unit 28, a post-processor 32 (or post-processing unit 32), and a display device 34.

[0106] The communications interface 28 of the destination device 14 is configured to receive the coded picture data 21 (or any further processed version thereof), for example, directly from the source device 12 or from any other source, for example, a storage device, for example, a coded picture data storage device, and to provide the coded picture data 21 to the decoder 30.

[0107] The communication interface 22 and the communication interface 28 may be configured to transmit or receive the encoded picture data 21 or the encoded data 13 via a direct communication link between the source device 12 and the destination device 14, e.g., a direct wired or wireless connection, or via any type of network, e.g., a wired or wireless network or any combination thereof, or any type of private and public network, or any combination thereof.

[0108] The communications interface 22 may be configured, for example, to package the coded picture data 21 into a suitable format, e.g., packets, and / or process the coded picture data using any type of transmission coding or processing for transmission over a communications link or network.

[0109] The communications interface 28, which forms the counterpart of the communications interface 22, may for example be configured to receive transmitted data and process the transmitted data using any type of corresponding transmission decoding or processing and / or unpackaging to obtain the coded picture data 21.

[0110] Both communication interface 22 and communication interface 28 may be configured as unidirectional communication interfaces, as indicated by the arrow for communication channel 13 pointing from source device 12 to destination device 14 in FIG. 1A, or as bidirectional communication interfaces, e.g., configured to send and receive messages, e.g., to set up connections, to authorize and exchange communication links and / or any other information related to data transmission, e.g., coded picture data transmission.

[0111] The decoder 30 is arranged to receive the coded picture data 21 and to provide decoded picture data 31 or decoded pictures 31 (as will be explained in further detail below, for example with reference to FIG. 3 or FIG. 5).

[0112] Post-processor 32 of destination device 14 is configured to post-process decoded picture data 31 (also called reconstructed picture data), e.g., decoded picture 31, to obtain post-processed picture data 33, e.g., post-processed picture 33. The post-processing performed by post-processing unit 32 may include, e.g., color format conversion (e.g., from YCbCr to RGB), color correction, cropping or resampling, or any other processing, e.g., to prepare decoded picture data 31 for display, e.g., by display device 34.

[0113] Display device 34 of destination device 14 is configured to receive the post-processed picture data 33 and, for example, display the picture to a user or viewer. Display device 34 may be or include any type of display that presents the reconstructed picture, for example, an integrated or external display or monitor. The display may be or include, for example, a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a plasma display, a projector, a microLED display, a liquid crystal on silicon (LCoS), a digital light processor (DLP), or any other type of display.

[0114] 1A depicts source device 12 and destination device 14 as separate devices, an embodiment of the devices may also include both or both functionality: source device 12 or corresponding functionality and destination device 14 or corresponding functionality. In such an embodiment, source device 12 or corresponding functionality and destination device 14 or corresponding functionality may be implemented using the same hardware and / or software or by separate hardware and / or software or any combination thereof.

[0115] As will be apparent to those skilled in the art based on the description, the presence and (exact) division of different units or functions within source device 12 and / or destination device 14 as shown in FIG. 1A may vary depending on the actual device and application.

[0116] Encoder 20 (e.g., video encoder 20) or decoder 30 (e.g., video decoder 30), or both encoder 20 and decoder 30, may be implemented via processing circuitry as shown in FIG. 1B , such as one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, hardware, dedicated video coding, or any combination thereof. Encoder 20 may be implemented via processing circuitry 46 to embody various modules as described with respect to encoder 20 of FIG. 2 and / or any other encoder system or subsystem described herein. Decoder 30 may be implemented via processing circuitry 46 to embody various modules as described with respect to decoder 30 of FIG. 3 and / or any other decoder system or subsystem described herein. The processing circuitry may be configured to perform various operations as described below. 5, where the techniques are implemented in part in software, a device may store instructions for the software in a suitable non-transitory computer-readable storage medium and may execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Either video encoder 20 and video decoder 30 may be integrated as part of a combined encoder / decoder (CODEC) in a single device, for example, as shown in FIG. 1B.

[0117] Source device 12 and destination device 14 may include any of a wide variety of devices, including any type of handheld or stationary device, e.g., a notebook or laptop computer, a mobile phone, a smartphone, a tablet or tablet computer, a camera, a desktop computer, a set-top box, a television, a display device, a digital media player, a video game console, a video streaming device (such as a content service server or content distribution server), a broadcast receiver device, a broadcast transmitter device, etc., and may or may not use any type of operating system. In some cases, source device 12 and destination device 14 may be equipped for wireless communication. Thus, source device 12 and destination device 14 may be wireless communication devices.

[0118] 1A is merely an example, and the techniques herein may be applied to video coding settings (e.g., video encoding or video decoding) that do not necessarily include any data communication between an encoding device and a decoding device. In other examples, data may be retrieved from local memory, streamed over a network, etc. A video encoding device may encode data and store it in memory, and / or a video decoding device may retrieve data from memory and decode it. In some examples, encoding and decoding are performed by devices that do not communicate with each other but simply encode data to memory and / or retrieve data from memory and decode it.

[0119] For ease of explanation, embodiments of the present invention are described herein with reference to, for example, High-Efficiency Video Coding (HEVC) or Versatile Video Coding (VVC) reference software, next-generation video coding standards developed by the ITU-T Video Coding Experts Group (VCEG) and the ISO / IEC Joint Collaboration Team on Video Coding (JCT-VC) of the Motion Picture Experts Group (MPEG). Those skilled in the art will understand that embodiments of the present invention are not limited to HEVC or VVC.

[0120] Encoder and encoding method FIG. 2 shows a schematic block diagram of an exemplary video encoder 20 configured to implement the techniques of the present application. In the example of FIG. 2, the video encoder 20 includes an input 201 (or input interface 201), a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a loop filter unit 220, a decoded picture buffer (DPB) 230, a mode selection unit 260, an entropy coding unit 270, and an output 272 (or output interface 272). The mode selection unit 260 may include an inter prediction unit 244, an intra prediction processing unit 254, and a partition unit 262. The inter prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown). The video encoder 20 shown in FIG. 2 may also be referred to as a hybrid video encoder or a video encoder using a hybrid video codec.

[0121] The residual calculation unit 204, the transform processing unit 206, the quantization unit 208, and the mode selection unit 260 may be referred to as forming a forward signal path of the encoder 20. Meanwhile, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the buffer 216, the loop filter 220, the decoded picture buffer (DPB) 230, the inter prediction unit 244, and the intra prediction unit 254 may be referred to as forming a backward signal path of the video encoder 20, which corresponds to the signal path of the decoder (see decoder 30 in FIG. 3 ). The inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the loop filter 220, the decoded picture buffer (DPB) 230, the inter prediction unit 244, and the intra prediction unit 254 may also be referred to as forming a “built-in decoder” of the video encoder 20.

[0122] Pictures and picture partitions (pictures and blocks) The encoder 20 may be configured to receive, for example, via input 201, a picture 17 (or picture data 17), e.g., a picture of a video or a sequence of pictures forming a video sequence. The received picture or picture data may also be a preprocessed picture 19 (preprocessed picture data 19). For simplicity, the following description refers to the picture 17. The picture 17 may also be called a current picture or a picture to be coded (particularly in video coding, to distinguish the current picture from other pictures, e.g., pictures that have been previously coded and / or decoded in the same video sequence, i.e., the video sequence that also includes the current picture).

[0123] A (digital) picture can be thought of as or be a two-dimensional array or matrix of samples with intensity values. The samples in the array may also be called pixels (short for picture element) or pels. The number of samples in the horizontal and vertical directions (or axes) of the array or picture defines the size and / or resolution of the picture. For color representation, three color components are typically used, i.e., a picture may be represented as or contain three sample arrays. In an RBG format or color space, a picture contains corresponding red, green, and blue sample arrays. However, in video coding, each pixel is typically represented in a luminance and chrominance format or color space, e.g., YCbCr, which contains a luminance component denoted by Y (sometimes L is used instead) and two chrominance components denoted by Cb and Cr. The luminance (or luma for short) component Y represents brightness or gray-level intensity (e.g., as in a grayscale picture). On the other hand, the two chrominance (or chroma for short) components Cb and Cr represent chromaticity or color information components. Thus, a picture in YCbCr format includes a luminance sample array of luminance sample values ​​(Y) and two chrominance sample arrays of chrominance values ​​(Cb and Cr). A picture in RGB format may be converted or transformed to YCbCr format, or vice versa; the process is also known as color conversion or translation. If a picture is monochrome, the picture may include only a luminance sample array. Thus, a picture may be, for example, an array of luma samples in monochrome format, or an array of luma samples and two corresponding arrays of chroma samples in 4:2:0, 4:2:2, and 4:4:4 color formats.

[0124] Embodiments of video encoder 20 may include a picture partition unit (not shown in FIG. 2) configured to partition picture 17 into multiple (typically non-overlapping) picture blocks 203. These blocks may also be called root blocks, macroblocks (H.264 / AVC) or coding tree blocks (CTBs) or coding tree units (CTUs) (H.265 / HEVC and VVC). The picture partition unit may be configured to use the same block size for all pictures of a video sequence and a corresponding grid that defines the block size, or to vary the block size among pictures or subsets or groups of pictures and partition each picture into corresponding blocks.

[0125] In further embodiments, the video encoder may be configured to directly receive blocks 203 of picture 17, e.g., one, some, or all of the blocks that form picture 17. Picture blocks 203 may also be referred to as current picture blocks or picture blocks to be coded.

[0126] Like picture 17, picture block 203 can also be considered as or be a two-dimensional array or matrix of samples having intensity values ​​(sample values), but with smaller dimensions than picture 17. In other words, block 203 may, for example, include one sample array (e.g., a luma array in the case of a monochrome picture 17, or a luma or chroma array in the case of a color picture) or three sample arrays (e.g., a luma and two chroma arrays in the case of a color picture 17), or any other number and / or type of arrays depending on the applied color format. The number of samples in the horizontal and vertical directions (or axes) of block 203 defines the size of block 203. Thus, a block may, for example, be an M×N (M columns by N rows) array of samples or an M×N array of transform coefficients.

[0127] An embodiment of video encoder 20 such as that shown in FIG. 2 may be configured to encode picture 17 on a block-by-block basis, eg, encoding and prediction is performed on a block-by-block basis.

[0128] Embodiments of video encoder 20 such as that shown in FIG. 2 may be further configured to partition and / or encode pictures using slices (also called video slices), where a picture may be partitioned into or encoded using one or more (typically non-overlapping) slices, each of which may include one or more blocks (e.g., CTUs) or groups of one or more blocks (e.g., tiles (H.265 / HEVC and VVC) or bricks (VVC)).

[0129] An embodiment of video encoder 20 as shown in FIG. 2 may be further configured to partition and / or encode a picture using slice / tile groups (also referred to as video tile groups) and / or tiles (also referred to as video tiles), where a picture may be partitioned into or encoded using one or more (typically non-overlapping) slice / tile groups, each of which may, for example, include one or more blocks (e.g., CTUs) or one or more tiles, and each tile may, for example, be rectangular in shape and include one or more blocks (e.g., CTUs), e.g., full or partial blocks.

[0130] Residual calculation The residual calculation unit 204 may be configured to calculate the residual block 205 based on the picture block 203 and the prediction block 265 (further details regarding the prediction block 265 are provided below), for example, by subtracting sample values ​​of the prediction block 265 from sample values ​​of the picture block 203 on a sample-by-sample (pixel-by-pixel) basis to obtain the residual block 205 in the sample domain.

[0131] conversion The transform processing unit 206 may be configured to apply a transform, such as a discrete cosine transform (DCT) or a discrete sine transform (DST), to the sample values ​​of the residual block 205 to obtain transform coefficients in a transform domain 207. The transform coefficients 207 may also be referred to as transform residual coefficients and represent the residual block 205 in the transform domain.

[0132] The transform processing unit 206 may be configured to apply an integer approximation of a DCT / DST, such as the transform specified for H.265 / HEVC. Compared to an orthogonal DCT transform, such an integer approximation is typically scaled by a specific factor. To maintain the norm of the residual block processed by the forward and inverse transforms, an additional scaling factor is applied as part of the transform process. The scaling factor is typically selected based on specific constraints, such as the scaling factor being a power of two due to shift operations, the bit depth of the transform coefficients, a trade-off between accuracy and implementation cost, etc. A specific scaling factor may be specified, for example, for the inverse transform by the inverse transform processing unit 212 (and the corresponding inverse transform by, e.g., the inverse transform processing unit 312 in the video decoder 30), and a corresponding scaling factor for the forward transform by, e.g., the transform processing unit 206 in the encoder 20 may be specified accordingly.

[0133] An embodiment of video encoder 20 (respectively, transform processing unit 206) may be configured to output transform parameters, e.g., a type of transform or multiple transforms, that are encoded or compressed, e.g., directly or via entropy coding unit 270, so that, for example, video decoder 30 may receive and use the transform parameters for decoding.

[0134] Quantization The quantization unit 208 may be configured to quantize the transform coefficients 207, for example by applying scalar quantization or vector quantization, to obtain quantized coefficients 209. The quantized coefficients 209 may also be referred to as quantized transform coefficients 209 or quantized residual coefficients 209.

[0135] The quantization process may reduce the bit depth associated with some or all of the transform coefficients 207. For example, an n-bit transform coefficient may be truncated to an m-bit transform coefficient during quantization, where n is greater than m. The degree of quantization may be changed by adjusting a quantization parameter (QP). For example, in scalar quantization, different scaling may be applied to achieve finer or coarser quantization. A smaller quantization step size corresponds to finer quantization, while a larger quantization step size corresponds to coarser quantization. The applicable quantization step may be indicated by the quantization parameter (QP). The quantization parameter may, for example, be an index into a predetermined set of applicable quantization step sizes. For example, a small quantization parameter may correspond to finer quantization (smaller quantization step size) and a large quantization parameter may correspond to coarser quantization (larger quantization step size), or vice versa. Quantization may involve division by a quantization step size, while the corresponding and / or inverse dequantization by, for example, the inverse quantization unit 210 may involve multiplication by the quantization step size. Some standards, such as HEVC, may be configured to use a quantization parameter to determine the quantization step size. Generally, the quantization step size may be calculated based on the quantization parameter using a fixed-point approximation of a formula that includes division. Due to the scaling used in the fixed-point approximation of the formula for the quantization step size and the quantization parameter, additional scaling factors for quantization and dequantization may be introduced to restore the norm of the residual block, which may change. In one exemplary implementation, the scaling of the inverse transform and dequantization may be combined. Alternatively, customized quantization tables may be used, e.g., signaled from the encoder to the decoder in the bitstream. Quantization is a lossy operation, and loss increases with increasing quantization step size.

[0136] The basic quantization parameters are signaled in the bitstream for all luma and chroma components together. However, the quantization parameters for the chrominance components can shift from the basic ones across pictures / slices or tile groups within a picture / coding unit within a slice or tile group level. For this purpose, the bitstream can include PPS offsets for the two chrominance components (pps_cb_qp_offset and pps_cr_qp_offset syntax elements), slice offsets for the two chrominance components (slice_cb_qp_offset and slice_cr_qp_offset), and two offset lists (cb_qp_offset_list and cr_qp_offset_list), which are usually signaled in the PPS and allow applying QP offsets at the CU level by sending a CU-level index pointing to a table.

[0137] Embodiments of video encoder 20 (respectively, quantization unit 208) may be configured to output a quantization parameter (QP), e.g., encoded directly or via entropy coding unit 270, so that, for example, video decoder 30 may receive and apply the quantization parameter for decoding.

[0138] inverse quantization The inverse quantization unit 210 is configured to apply the inverse quantization of the quantization unit 208 to the quantized coefficients, e.g., by applying the inverse of the quantization scheme applied by the quantization unit 208, based on or using the same quantization step size as the quantization unit 208, to obtain dequantized coefficients 211. The dequantized coefficients 211 are also referred to as dequantized residual coefficients 211 and may correspond to the transform coefficients 207, although they are typically not identical to the transform coefficients due to loss due to quantization.

[0139] Inverse transformation The inverse transform processing unit 212 is configured to apply an inverse transform of the transform applied by the transform processing unit 206, such as an inverse discrete cosine transform (DCT) or an inverse discrete sine transform (DST) or other inverse transform, to obtain a reconstructed residual block 213 (or corresponding dequantized coefficients 213) in the sample domain. The reconstructed residual block 213 may also be referred to as a transform block 213.

[0140] Reconstruction The reconstruction unit 214 (e.g., an adder or summer 214) is configured to add the transform block 213 (i.e., the reconstructed residual block 213) to the prediction block 265, e.g., by adding the sample values ​​of the reconstructed residual block 213 and the sample values ​​of the prediction block 265 sample by sample, to obtain the reconstructed block 215 in the sample domain.

[0141] filtering The loop filter unit 220 (or "loop filter" 220 for short) is configured to filter the reconstructed block 215 to obtain a filtered block 221, or generally, to filter the reconstructed samples to obtain filtered sample values. The loop filter unit is configured, for example, to smooth pixel transitions or improve video quality. The loop filter unit 220 may include one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or one or more other filters, such as an adaptive loop filter (ALF), a noise suppression filter (NSF), or any combination thereof. In one example, the loop filter unit 220 may include a deblocking filter, an SAO filter, and an ALF filter. The filtering process order may be deblocking filter, SAO, and ALF. In another example, a process called luma mapping with chroma scaling (LMCS) (i.e., adaptive in-loop reshaper) is added. This process is performed before deblocking. In other examples, the deblocking filter process may also be applied to internal sub-block edges, such as affine sub-block edges, ATMVP sub-block edges, sub-block transform (SBT) edges, and intra sub-partition (ISP) edges. Although loop filter unit 220 is shown in FIG. 2 as being an in-loop filter, in other configurations, loop filter unit 220 may be implemented as a post-loop filter. Filtered block 221 may also be referred to as filtered reconstruction block 221.

[0142] An embodiment of video encoder 20 (respectively, loop filter unit 220) may be configured to output loop filter parameters (such as SAO filter parameters or ALF filter parameters or LMCS parameters), which may be encoded, for example, directly or via entropy encoding unit 220, so that, for example, decoder 30 may receive and apply the same loop filter parameters or respective loop filters for decoding.

[0143] Decoded Picture Buffer The decoded picture buffer (DPB) 230 may be a memory that stores reference pictures, or reference picture data in general, for encoding video data by the video encoder 20. The DPB 230 may be formed from any of a variety of memory devices, such as dynamic random access memory (DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The decoded picture buffer (DPB) 230 may be configured to store one or more filtered blocks 221. The decoded picture buffer 230 may be further configured to store other previously filtered blocks, e.g., previously reconstructed filtered blocks 221, of the same current picture or a different picture, e.g., a previously reconstructed picture, and may provide a complete previously reconstructed, i.e., decoded, picture (and corresponding reference blocks and samples) and / or a partially reconstructed current picture (and corresponding reference blocks and samples), e.g., for inter prediction. The decoded picture buffer (DPB) 230 may also be configured to store one or more unfiltered reconstructed blocks 215, or in general, unfiltered reconstructed samples, e.g., if the reconstructed blocks 215 are not filtered by the loop filter unit 220, or other further processed versions of any of the reconstructed blocks or samples.

[0144] Mode selection (partition and prediction) The mode selection unit 260 includes a partition unit 262, an inter prediction unit 244, and an intra prediction unit 254, and is configured to receive or obtain original picture data, e.g., original block 203 (current block 203 of current picture 17), and reconstructed picture data, e.g., filtered and / or unfiltered reconstructed samples or blocks of the same (current) picture and / or from one or more previously decoded pictures, e.g., from the decoded picture buffer 230 or other buffer (e.g., a line buffer, not shown). The reconstructed picture data is used as reference picture data for prediction, e.g., inter prediction or intra prediction, to obtain a prediction block 265 or predictor 265.

[0145] The mode selection unit 260 may be configured to determine or select a partition (including no partition) and a prediction mode (e.g., intra or inter prediction mode) for the current block prediction mode, and generate a corresponding prediction block 265 used for calculating the residual block 205 and for reconstructing the reconstruction block 215.

[0146] Embodiments of mode selection unit 260 may be configured to select partitions and prediction modes (e.g., from those supported or available by mode selection unit 260) that provide the best fit, or in other words, the smallest residual (smallest residual means better compression for transmission or storage) or the smallest signaling overhead (smallest signaling overhead means better compression for transmission or storage), or that consider or balance both. Mode selection unit 260 may also be configured to determine partitions and prediction modes based on rate distortion optimization (RDO), i.e., to select a prediction mode that provides the smallest rate distortion. Terms such as “best,” “minimum,” “optimum,” etc. in this context do not necessarily indicate an overall “best,” “minimum,” “optimum,” etc., but may indicate the satisfaction of termination or selection criteria, such as values ​​above or below a threshold, or other constraints that potentially result in a “suboptimal selection,” but reduce complexity and processing time.

[0147] In other words, the partition unit 262 may be configured to partition pictures from a video sequence into a sequence of coding tree units (CTUs), and the CTUs 203 may be further partitioned into smaller block partitions or sub-blocks (which again form blocks), for example using quad-tree partitioning (QT), binary partitioning (BT) or triple-tree partitioning (TT) or any combination thereof repeatedly, and perform prediction for each of the block partitions or sub-blocks, where the mode selection includes selecting a tree structure of the partitioned block 203, and a prediction mode is applied to each of the block partitions or sub-blocks.

[0148] The partitioning (eg, by partition unit 260) and prediction processes (by inter prediction unit 244 and intra prediction unit 254) performed by exemplary video encoder 20 are described in further detail below.

[0149] partition The partition unit 262 may be configured to partition a picture from a video sequence into a sequence of coding tree units (CTUs), and the partition unit 262 may partition (or divide) the coding tree units (CTUs) 203 into smaller partitions, e.g., smaller blocks of square or rectangular size. For a picture with a three-sample arrangement, a CTU consists of an N×N block of luma samples along with two corresponding blocks of chroma samples. The maximum allowable size of a luma block within a CTU is specified as 128×128 in the current Versatile Video Coding (VVC) standard, but may be specified as a value other than 128×128, e.g., 256×256, in the future. CTUs of a picture may be clustered / grouped into slices / tile groups, tiles, or bricks. A tile covers a rectangular area of ​​the picture, and a tile can be divided into one or more bricks. A brick consists of multiple rows of CTUs within a tile. A tile that is not partitioned into multiple bricks can be called a brick. However, a brick is a true subset of a tile and is not called a tile. There are two modes of tile groups supported by VVC: raster scan slice / tile group mode and rectangular slice mode. In raster scan tile group mode, a slice / tile group contains a sequence of tiles in the tile raster scan of the picture. In rectangular slice mode, a slice contains multiple bricks of the picture that collectively form a rectangular region of the picture. The bricks within a rectangular slice are in the order of the brick raster scan of the slice. These smaller blocks (which may also be called sub-blocks) may be further partitioned into even smaller partitions.This is also called tree partitioning or hierarchical tree partitioning; for example, a root block at root tree level 0 (hierarchical level 0, depth 0) may be recursively partitioned, e.g., into two or more blocks at the next lower tree level, e.g., into nodes at tree level 1 (hierarchical level 1, depth 1); these blocks may then be partitioned again into two or more blocks at the next lower tree level, e.g., tree level 2 (hierarchical level 2, depth 2), until partitioning terminates, e.g., because a termination criterion is met, e.g., a maximum tree depth or a minimum block size is reached. Furthermore, unpartitioned blocks are also called leaf blocks or leaf nodes of the tree. A tree using partitions into two partitions is called a binary tree (BT), a tree using partitions into three partitions is called a ternary tree (TT), and a tree using partitions into four partitions is called a quad tree (QT).

[0150] For example, a coding tree unit (CTU) may be or include a CTB of luma samples, two corresponding CTBs of chroma samples for a picture with a three-sample arrangement, or a CTB of samples for a monochrome picture or a picture coded using a syntax structure used for coding three separate color planes and samples. Correspondingly, a coding tree block (CTB) may be an N×N block of samples, for some value of N, whereby the division of the components into CTBs is a partition. A coding unit (CU) may be or include a coding block of luma samples, two corresponding coding blocks of chroma samples for a picture with a three-sample arrangement, or a coding block of samples for a monochrome picture or a picture coded using a syntax structure used for coding three separate color planes and samples. Correspondingly, a coding block (CB) may be an M×N block of samples, for some values ​​of M and N, whereby the division of the CTB into coding blocks is a partition.

[0151] For example, in an HEVC-based embodiment, coding tree units (CTUs) may be divided into CUs by using a quadtree structure, denoted as a coding tree. The decision of whether to code a picture region using inter-picture (temporal) prediction or intra-picture (spatial) prediction is made at the leaf CU level. Each leaf CU can be further divided into one, two, or four PUs according to the PU partition type. Within one PU, the same prediction process is applied, and related information is sent to the decoder for each PU. After obtaining residual blocks by applying the prediction process based on the PU partition type, the leaf CUs can be partitioned into transform units (TUs) according to another quadtree structure similar to the coding tree for CUs.

[0152] For example, in an embodiment according to the latest video coding standard currently under development, called Versatile Video Coding (VVC), a combined quadtree nested multitype tree using bisection and trisection segmentation structures is used to partition the coding tree units, for example. In the coding tree structure within a coding tree unit, the CUs can have either a square or rectangular shape. For example, a coding tree unit (CTU) is first partitioned by a quadtree. The quadtree leaf nodes can then be further partitioned by a multitype tree structure. There are four split types in the multitype tree structure: vertical bisection (SPLIT_BT_VER), horizontal bisection (SPLIT_BT_HOR), vertical trisection (SPLIT_TT_VER), and horizontal trisection (SPLIT_TT_HOR). The multitype tree leaf nodes are called coding units (CUs), and this segmentation is used for prediction and transform processes without further partitioning, as long as the CUs are not too large for the maximum transform length. This means that in most cases, CUs, PUs, and TUs have the same block size in the quadtree with the coding block structure of the nested multitype tree. An exception occurs when the maximum supported transform length is smaller than the width or height of the color components of the CU. VVC has developed a unique signaling mechanism for partitioning information in the quadtree with the coding tree structure of the nested multitype tree. In this signaling mechanism, a coding tree unit (CTU) is treated as the root of the quadtree and is first partitioned by the quadtree structure. Then, each quadtree leaf node (when large enough to allow it) is further partitioned by the multitype tree structure.In a multi-type tree structure, a first flag (mtt_split_cu_flag) is signaled to indicate whether a node is further partitioned; when the node is further partitioned, a second flag (mtt_split_cu_vertical_flag) is signaled to indicate the split direction; and then a third flag (mtt_split_cu_binary_flag) is signaled to indicate whether the split is bipartite or tripartite. Based on the values ​​of mtt_split_cu_vertical_flag and mtt_split_cu_binary_flag, the multi-type tree split mode (MttSplitMode) of the CU can be derived by the decoder based on a predetermined rule or table. As shown in Figure 6, in a specific design, for example, a 64x64 luma block and 32x32 chroma pipeline design in a VVC hardware decoder, TT splitting is prohibited when either the width or height of the luma coding block is greater than 64. TT partitioning is also prohibited when either the width or height of a chroma coding block is greater than 32. The pipeline design divides a picture into virtual pipeline data units (VPDUs), which are defined as non-overlapping units within a picture. In a hardware decoder, consecutive VPDUs are processed simultaneously by multiple pipeline stages. Because the VPDU size is roughly proportional to the buffer size in most pipeline stages, it is important to keep the VPDU size small. In most hardware decoders, the VPDU size can be set to the maximum transform block (TB) size. However, in VVC, ternary tree (TT) and binary tree (BT) partitioning can result in an increase in VPDU size.

[0153] Furthermore, it should be noted that when part of a tree node block exceeds the bottom or right picture boundary, the tree node block is forced to be split until all samples of all coded CUs are located within the picture boundary.

[0154] As an example, an Intra Sub-Partitions (ISP) tool may divide a luma intra-prediction block vertically or horizontally into two or four sub-partitions, depending on the block size.

[0155] In one example, mode select unit 260 of video encoder 20 may be configured to perform any combination of the partitioning techniques described herein.

[0156] As described above, video encoder 20 is configured to determine or select a best or optimal prediction mode from a (e.g., predetermined) set of prediction modes, which may include, for example, intra-prediction modes and / or inter-prediction modes.

[0157] Intra prediction The set of intra prediction modes may include 35 different intra prediction modes, e.g., non-directional modes such as DC (or average) mode and planar mode, or directional modes as defined in HEVC, or 67 different intra prediction modes, e.g., non-directional modes such as DC (or average) mode and planar mode, or directional modes as defined in VVC. As an example, some conventional angular intra prediction modes are adaptively replaced with wide-angle intra prediction modes for non-square blocks, e.g., as defined in VVC. As another example, to avoid a split operation for DC prediction, only the long side is used to calculate the average for non-square blocks. Furthermore, the results of planar mode intra prediction may be further modified by a position-dependent intra prediction combination (PDPC) method.

[0158] The intra prediction unit 254 is configured to use reconstructed samples of neighboring blocks of the same current picture to generate an intra prediction block 265 according to an intra prediction mode from a set of intra prediction modes.

[0159] The intra prediction unit 254 (or generally the mode selection unit 260) is further configured to output the intra prediction parameters (or generally information indicating the selected intra prediction mode for the block) to the entropy coding unit 270 in the form of a syntax element 226 for inclusion in the coded picture data 21, so that, for example, the video decoder 30 may receive and use the prediction parameters for decoding.

[0160] Inter Prediction The set (or possibilities) of inter prediction modes depends on the available reference pictures (i.e., previous at least partially decoded pictures, e.g., stored in DBP 230) and other inter prediction parameters, such as whether the entire reference picture is used to search for the best matching reference block, or whether only a portion of the reference picture, e.g., a search window area around the area of ​​the current block, is used, and / or whether pixel interpolation, e.g., half / semi-pel, quarter-pel and / or 1 / 16-pel interpolation, is applied.

[0161] In addition to the prediction modes mentioned above, skip mode, direct mode and / or other inter prediction modes may also be applied.

[0162] For example, in enhanced merge prediction, the merge candidate list for such a mode is constructed by including the following five types of candidates, in order: spatial MVP from spatially neighboring CUs, temporal MVP from co-located CUs, history-based MVP from a FIFO table, pairwise average MVP, and zero MV. Furthermore, to improve the accuracy of the MV in the merge mode, bilateral matching-based decoder-side motion vector refinement (DMVR) may be applied. Merge mode with MVD (MMVD) is derived from merge mode with motion vector difference (MVD). To specify whether the MMVD mode is used for a CU, an MMVD flag is signaled immediately after sending the skip flag and merge flag. Furthermore, a CU-level adaptive motion vector resolution (AMVR) scheme may be applied. AMVR allows the MVD of a CU to be coded with different precision. The MVD of the current CU can be adaptively selected depending on the prediction mode for the current CU. When a CU is coded in merge mode, the combined inter / intra prediction (CIIP) mode may be applied to the current CU. To obtain the CIIP prediction, a weighted average of the inter and intra prediction signals is performed. In affine motion compensation prediction, the affine motion field of a block is described by motion information of two control points (four parameters) or three control point motion vectors (six parameters). Sub-block-based temporal motion vector prediction (SbTMVP) is similar to temporal motion vector prediction (TMVP) in HEVC, but predicts the motion vectors of sub-CUs within the current CU.Bidirectional optical flow (BDOF), formerly called BIO, is a simpler version that requires significantly less computational effort, especially in terms of the number of multiplications and the size of the multipliers. In triangular partition mode, in such mode, the CU is evenly divided into two triangular-shaped partitions using either diagonal or non-diagonal partitioning. Furthermore, bi-prediction mode is extended beyond simple averaging to allow for weighted averaging of the two prediction signals.

[0163] The inter prediction unit 244 may include a motion estimation (ME) unit and a motion compensation (ME) unit (both not shown in FIG. 2 ). The motion estimation unit may be configured to receive or obtain, for motion estimation, a picture block 203 (current block 203 of current picture 17) and a decoded picture 231, or at least one or more previously reconstructed blocks, e.g., reconstructed blocks of one or more other / different previous decoded pictures 231. For example, a video sequence may include the current picture and the previous decoded picture 231, or in other words, the current picture and the previous decoded picture 231 may be part of or form a sequence of pictures that form a video sequence.

[0164] The encoder 20 may be configured to, for example, select a reference block from multiple reference blocks of the same or different pictures and provide the reference picture (or reference picture index) and / or an offset (spatial offset) between the position (x, y coordinates) of the reference block and the position of the current block to the motion estimation unit as an inter-prediction parameter. This offset is also called a motion vector (MV).

[0165] The motion compensation unit is configured to obtain, e.g., receive, inter prediction parameters and perform inter prediction based on or using the inter prediction parameters to obtain an inter prediction block 265. The motion compensation performed by the motion compensation unit may include fetching or generating a prediction block based on motion / block vectors determined by motion estimation, and possibly performing interpolation to sub-pixel accuracy. Interpolation filtering may generate additional pixel samples from known pixel samples, thus potentially increasing the number of candidate prediction blocks that can be used to code the picture block. Upon receiving the motion vector of the PU of the current picture block, the motion compensation unit may find the prediction block to which the motion vector points in one of the reference picture lists.

[0166] The motion compensation unit may also generate syntax elements associated with the blocks and video slices for use by video decoder 30 in decoding picture blocks of the video slices. In addition to or as an alternative to slices and their respective syntax elements, tile groups and / or tiles and their respective syntax elements may be generated or used.

[0167] Entropy Coding The entropy coding unit 270 is configured to, for example, apply or bypass (uncompress) an entropy coding algorithm or scheme (e.g., a variable length coding (VLC) scheme, a context adaptive VLC (CAVLC) scheme, an arithmetic coding scheme, binarization, context adaptive binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding, or other entropy coding method or technique) to the quantized coefficients 209, the inter-prediction parameters, the intra-prediction parameters, the loop filter parameters, and / or other syntax elements to obtain coded picture data 21 that can be output via output 272, for example, in the form of coded bitstream 21, so that, for example, video decoder 30 may receive and use the parameters for decoding. Encoded bitstream 21 may be transmitted to video decoder 39 or may be stored in memory for later transmission or retrieval by video decoder 30 .

[0168] Other structural variations of the video encoder 20 can be used to encode the video stream. For example, a non-transform-based encoder 20 can directly quantize the residual signal for a particular block or frame, without the transform processing unit 206. In other implementations, the encoder 20 can have the quantization unit 208 and the inverse quantization unit 210 combined into a single unit.

[0169] Decoder and decoding method 3 shows an example of a video decoder 30 configured to implement the techniques of the present application. The video decoder 30 is configured to receive coded picture data 21 (e.g., coded bitstream 21), for example, coded by encoder 20, to obtain a decoded picture 331. The coded picture data or bitstream includes information for decoding the coded picture data, for example, data representing picture blocks of coded video slices (and / or tile groups or tiles) and associated syntax elements.

[0170] 3, decoder 30 includes an entropy decoding unit 304, an inverse quantization unit 310, an inverse transform processing unit 312, a reconstruction unit 314 (e.g., summer 314), a loop filter 320, a decoded picture buffer (DBP) 330, a mode application unit 360, an inter prediction unit 344, and an intra prediction unit 354. Inter prediction unit 344 may be or include a motion compensation unit. Video decoder 30, in some examples, may perform a decoding path that is generally inverse to the encoding path described with respect to video encoder 100 from FIG. 2.

[0171] As described with respect to encoder 20, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, loop filter 220, decoded picture buffer (DPB) 230, inter prediction unit 344, and intra prediction unit 354 may also be referred to as forming a “built-in decoder” of video encoder 20. Accordingly, inverse quantization unit 310 may be functionally identical to inverse quantization unit 110, inverse transform processing unit 312 may be functionally identical to inverse transform processing unit 212, reconstruction unit 314 may be functionally identical to reconstruction unit 214, loop filter 320 may be functionally identical to loop filter 220, and decoded picture buffer 330 may be functionally identical to decoded picture buffer 230. Accordingly, the descriptions provided for the respective units and functions of video encoder 20 also apply correspondingly to the respective units and functions of video decoder 30.

[0172] Entropy Decoding The entropy decoding unit 304 is configured to parse the bitstream 21 (or generally, the coded picture data 21) and, e.g., perform entropy decoding on the coded picture data 21 to obtain, e.g., quantized coefficients 309 and / or decoded coding parameters (not shown in FIG. 3 ), such as inter-prediction parameters (e.g., reference picture indices and motion vectors), intra-prediction parameters (e.g., intra-prediction modes or indices), transform parameters, quantization parameters, loop filter parameters, and / or other syntax elements. The entropy decoding unit 304 may be configured to apply a decoding algorithm or scheme corresponding to an encoding scheme such as those described with respect to the entropy coding unit 270 of the encoder 20. The entropy decoding unit 304 may be further configured to provide the inter-prediction parameters, intra-prediction parameters, and / or other syntax elements to the mode application unit 360 and to provide other parameters to other units of the decoder 30. The video decoder 30 may receive video slice-level and / or video block-level syntax elements. In addition to or as an alternative to slices and their respective syntax elements, tile groups and / or tiles and their respective syntax elements may be received and / or used.

[0173] inverse quantization Inverse quantization unit 310 may be configured to receive a quantization parameter (QP) (or generally, information regarding inverse quantization) and quantized coefficients from coded picture data 21 (e.g., by parsing and / or decoding by entropy decoding unit 304, for example), and apply inverse quantization to the decoded quantized coefficients 309 based on the quantization parameter to obtain dequantized coefficients 311, which may also be referred to as transform coefficients 311. The inverse quantization process may involve using the quantization parameter determined by video encoder 20 for each video block within a video slice (or tile or tile group) to determine the degree of quantization, and similarly the degree of inverse quantization, to be applied.

[0174] Inverse transformation The inverse transform processing unit 312 may be configured to receive the dequantized coefficients 311, also referred to as transform coefficients 311, and apply a transform to the dequantized coefficients 311 to obtain the reconstructed residual block 213 in the sample domain. The reconstructed residual block 213 may also be referred to as the transform block 313. The transform may be an inverse transform, e.g., an inverse DCT, an inverse DST, an inverse integer transform, or a conceptually similar inverse transform process. The inverse transform processing unit 312 may further be configured to receive transform parameters or corresponding information from the coded picture data 21 (e.g., by parsing and / or decoding by the entropy decoding unit 304) to determine the transform to be applied to the dequantized coefficients 311.

[0175] Reconstruction The reconstruction unit 314 (e.g., an adder or summer 314) may be configured to add the reconstructed residual block 313 to the prediction block 365, e.g., by adding sample values ​​of the reconstructed residual block 313 and sample values ​​of the prediction block 365, to obtain a reconstructed block 315 in the sample domain.

[0176] filtering The loop filter unit 320 (either in the coding loop or after the coding loop) is configured to filter the reconstructed block 315 to obtain a filtered block 321, e.g., to smooth pixel transitions or improve video quality. The loop filter unit 320 may include one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or one or more other filters, e.g., an adaptive loop filter (ALF), a noise suppression filter (NSF), or any combination thereof. In one example, the loop filter unit 320 may include a deblocking filter, an SAO filter, and an ALF filter. The order of the filtering processes may be deblocking filter, SAO, and ALF. In another example, a process called luma mapping with chroma scaling (LMCS) (i.e., adaptive in-loop reshaper) is added. This process is performed before deblocking. In other examples, the deblocking filter process may also be applied to internal sub-block edges, e.g., affine sub-block edges, ATMVP sub-block edges, sub-block transform (SBT) edges, and intra sub-partition (ISP) edges. Although loop filter unit 320 is shown in FIG. 3 as being an in-loop filter, in other configurations, loop filter unit 320 may be implemented as a post-loop filter.

[0177] Decoded Picture Buffer The decoded video blocks 321 of the picture are then stored in a decoded picture buffer 330, which stores the decoded picture 331 as a reference picture for later motion compensation for other pictures and / or for output for respective display.

[0178] The decoder 30 is arranged to output the decoded pictures 331, for example via output 312, for presentation or viewing to a user.

[0179] prediction The inter prediction unit 344 may be identical to the inter prediction unit 244 (in particular the motion compensation unit), and the intra prediction unit 354 may be functionally identical to the inter prediction unit 254, and performs the division or partition decision and prediction based on the partition and / or prediction parameters or respective information received from the coded picture data 21 (e.g., by parsing and / or decoding by the entropy decoding unit 304). The mode application unit 360 may be configured to perform prediction (intra or inter prediction) for each block based on the reconstructed picture, block or respective (filtered or unfiltered) samples to obtain a prediction block 365.

[0180] When a video slice is coded as an intra-coded (I) slice, intra prediction unit 354 of mode application unit 360 is configured to generate a predictive block 365 for a picture block of the current video slice based on the signaled intra prediction mode and data from a previously decoded block of the current picture. When a video picture is coded as an inter-coded (i.e., B or P) slice, inter prediction unit 344 (e.g., a motion compensation unit) of mode application unit 360 is configured to generate a predictive block 365 for a video block of the current video slice based on the motion vector and other syntax elements received from entropy decoding unit 304. In inter prediction, the predictive block may be generated from one of the reference pictures in one of the reference picture lists. Video decoder 30 may construct the reference frame lists, List 0 and List 1, using a default construction technique based on the reference pictures stored in DPB 330. The same or similar may apply to or by embodiments that use tile groups (e.g., video tile groups) and / or tiles (e.g., video tiles) in addition to or as an alternative to slices (e.g., video slices), e.g., video may be coded using I, P, or B tile groups and / or tiles.

[0181] Mode application unit 360 is configured to determine prediction information for video blocks of the current video slice by parsing motion vectors or related information and other syntax elements, and uses the prediction information to generate predictive blocks for the current video block being decoded. For example, mode application unit 360 uses some of the received syntax elements to determine the prediction mode (e.g., intra or inter prediction) to be used for coding the video blocks of the video slice, the inter-prediction slice type (e.g., B slice, P slice, or GPB slice), configuration information for one or more of the slice's reference picture lists, motion vectors for each inter-coded video block of the slice, inter-prediction states for each inter-coded video block of the slice, and other information for decoding video blocks in the current video slice. The same or similar techniques may be applied to or with embodiments that use tile groups (e.g., video tile groups) and / or tiles (e.g., video tiles) in addition to or as an alternative to slices (e.g., video slices), e.g., video may be coded using I, P, or B tile groups and / or tiles.

[0182] Embodiments of video decoder 30 such as that shown in FIG. 3 may be configured to partition and / or decode pictures using slices (also called video slices), where a picture may be partitioned into or decoded using one or more (typically non-overlapping) slices, each of which may include one or more blocks (e.g., CTUs) or groups of one or more blocks (e.g., tiles (H.265 / HEVC and VVC or bricks (VVC)).

[0183] An embodiment of video decoder 30 such as that shown in FIG. 3 may be configured to partition and / or decode a picture using slice / tile groups (also referred to as video tile groups) and / or tiles (also referred to as video tiles), where a picture may be partitioned into or decoded using one or more (typically non-overlapping) slice / tile groups, each of which may include, for example, one or more blocks (e.g., CTUs) or one or more tiles, and each tile may be, for example, rectangular in shape and may include one or more blocks (e.g., CTUs), e.g., full or partial blocks.

[0184] Other variations of the video decoder 30 may be used to decode the coded picture data 21. For example, the decoder 30 may generate the output video stream without the loop filter unit 320. For example, a non-transform-based decoder 30 may directly inverse quantize the residual signal for a particular block or frame without the inverse transform processing unit 312. In other implementations, the video decoder 30 may have the inverse quantization unit 310 and the inverse transform processing unit 312 combined into a single unit.

[0185] It should be understood that in the encoder 20 and the decoder 30, the processing result of the current step may be further processed and then output to the next step. For example, after interpolation filtering, motion vector derivation or loop filtering, further operations such as clipping or shifting may be performed on the processing result of the interpolation filtering, motion vector derivation or loop filtering.

[0186] It should be noted that further operations may be applied to the derived motion vector of the current block (including, but not limited to, control point motion vectors in affine mode, sub-block motion vectors in affine, planar, and ATMVP modes, temporal motion vectors, etc.). For example, the value of a motion vector is constrained to a predetermined range according to its representation bits. If the representation bits of a motion vector are bitDepth, the range is -2^(bitDepth-1) to 2^(bitDepth-1)-1, where "^" means exponentiation. For example, if bitDepth is set equal to 16, the range is -32768 to 32767, and if bitDepth is set equal to 18, the range is -131072 to 131071. For example, the value of a derived motion vector (e.g., the MVs of four 4x4 sub-blocks in one 8x8 block) is constrained so that the maximum difference between the integer parts of the MVs of the four 4x4 sub-blocks is not more than N pixels, such as not more than 1 pixel. Here, we provide two methods for constraining motion vectors according to bitDepth.

[0187] 4 is a schematic diagram of a video coding device 400 according to an embodiment of the present disclosure. Video coding device 400 is suitable for implementing embodiments of the disclosure as described herein. In an embodiment, video coding device 400 may be a decoder, such as video decoder 30 of FIG. 1A, or an encoder, such as video encoder 20 of FIG. 1A.

[0188] Video coding device 400 includes an ingress port 410 (or input port 410) and a receiver unit (Rx) 420 for receiving data, a processor, logic unit, or central processing unit (CPU) 430 for processing data, a transmitter unit (Tx) 440 and an egress port 450 (or output port 450) for transmitting data, and a memory 460 for storing data. Video coding device 400 may also include optical-to-electrical (OE) and electrical-to-optical (EO) components coupled to ingress port 410, receiver unit 420, transmitter unit 440, and egress port 450 for the egress or ingress of optical or electrical signals.

[0189] The processor 430 is implemented in hardware and software. The processor 430 may be implemented as one or more CPU chips, cores (e.g., multi-core processors), FPGAs, ASICs, and DSPs. The processor 430 communicates with the ingress port 410, the receiver unit 420, the transmitter unit 440, the egress port 450, and the memory 460. The processor 430 includes a coding module 470. The coding module 470 implements the disclosed embodiments described above. For example, the coding module 470 implements, processes, prepares, or provides various coding operations. Thus, what is included in the coding module 470 provides substantial improvements to the functionality of the video coding device 400 and results in the transformation of the video coding device 400 into a different state. Alternatively, the coding module 470 is implemented as instructions stored in the memory 460 and executed by the processor 430.

[0190] Memory 460 may include one or more disks, tape drives, and solid-state drives, and may be used for storing programs when such programs are selected for execution and as an overflow data storage device for storing instructions and data read during the execution of the programs. Memory 460 may be, for example, volatile and / or non-volatile, and may be read-only memory (ROM), random access memory (RAM), ternary content-addressable memory (TCAM), and / or static random-access memory (SRAM).

[0191] FIG. 5 is a simplified block diagram of an apparatus 500 that may be used as one or both of source device 12 and destination device 14 from FIG. 1A according to an example embodiment.

[0192] Processor 502 in device 500 may be a central processing unit. Alternatively, processor 502 may be any other type of device or devices, now existing or later developed, that can manipulate or process information. While the disclosed implementations may be implemented with a single processor, such as processor 502, as shown, advantages in speed and efficiency may be achieved using more than one processor.

[0193] The memory 504 in the apparatus 500 may, in implementation, be a read only memory (ROM) device or a random access memory (RAM) device. Any other suitable type of storage device may be used as the memory 504. The memory 504 may include code and data 506 that is accessed by the processor 502 using a bus 512. The memory 504 may further include an operating system 508 and application programs 510, which include at least one program that enables the processor 502 to perform methods described herein. For example, the application programs 510 may include applications 1-N, which may further include a video coding application that performs methods described herein.

[0194] The apparatus 500 may also include one or more output devices, such as a display 518. The display 518 may, in one example, be a touch-sensitive display that combines a display with a touch-sensitive element operable to sense touch input. The display 518 may be coupled to the processor 502 via the bus 512.

[0195] Although shown here as a single bus, bus 512 of device 500 may be comprised of multiple buses. Additionally, secondary storage 514 may be directly coupled to other components of device 500 or may be accessible over a network and may include a single integrated unit such as a memory card or multiple units such as multiple memory cards. Thus, device 500 may be implemented in a wide variety of configurations.

[0196] Joint Coding of Chrominance Residuals (JVET-M0305) Joint coding of chrominance residual proposes a chrominance residual coding mode in which a single joint residual block is used to describe the residuals of both Cb and Cr blocks within the same transform unit. When the joint residual mode is active, the indicated joint residual is added to the Cb prediction block and subtracted from the Cr prediction block. On the encoder side, the algorithm uses the average of the positive Cb residual and the negative Cr residual as input to the transform and quantization process.

[0197] The concept of joint coding of Cb and Cr is based on the fact that the Cb and Cr residuals are inversely correlated with each other. In this mode, there is a single residual signal for the two chrominance blocks of the transform unit. The signaled residual is added to the predicted block in the first channel (typically representing Cb) and subtracted from the predicted block in the second channel (typically representing Cr).

[0198] If the coded block flags (cbf) for both Cb and Cr are true, the joint residual mode is indicated by a flag in the bitstream. When the mode is activated, a single residual block is decoded. The bitstream syntax and decoding process of the joint residual block follow that of the Cb residual in VTM-3. The residual of the Cr block is generated by canceling the decoded joint residual. Because a single residual is used to represent the residual of two blocks, the chroma QP offset parameter is reduced by 2 when the joint chrominance residual mode is active.

[0199] At the encoder side, the average of the positive Cb residual and the negative Cr residual is used as the joint residual. resJoint=(resCb-resCr) / 2

[0200] Joint Chroma Residual Coding in Multiple Modes (JVET-N0282) Joint chroma residual coding in multiple modes is an extension of the joint chroma residual coding proposed in JVET-M0305. In contrast to JVET-M0305, which proposes the addition of one joint chroma residual coding mode (given by Cr = -Cb), this contribution proposes three modes for joint chroma residual coding (given by Cr = ±Cb / 2, Cr = ±Cb, and Cb = ±Cr / 2) with different blending factors. The code used to derive the second chroma residual is coded in the tile group header. The use of the joint chroma coding mode is indicated by a flag at the TU level, and the selected mode is implicitly indicated by the chroma-coded block flag.

[0201] Three modes for joint chroma residual coding are supported: In all three of these joint chroma residual coding modes, a single chroma transform block is coded (using VTM4 residual coding) and other blocks of chroma residual samples are derived using simple arithmetic operations.

[0202] The following three joint chroma coding modes are supported: Mode 1: Cb is coded and Cr is derived according to Cr=CSign*Cb / 2 Mode 2: Cb is coded and Cr is derived according to Cr=CSign*Cb Mode 3: Cr is coded and Cb is derived according to Cb=CSign*Cr / 2 where CSign represents the code used to derive the second chroma residual block. CSign is indicated using the tile group header syntax element, which is either −1 or 1. Note that when CSign is equal to −1, mode 2 is the same as the joint chroma coding mode proposed in JVET-M0305.

[0203] The use of joint chroma residual coding is indicated by the TU-level flag tu_joint_chroma_residual_flag. This flag is present if either or both of the two chroma coded block flag (CBF) syntax elements are equal to 1. If tu_joint_chroma_residual_flag is equal to 1, one of the joint chroma residual coding modes is used. The mode used is indicated by the chroma CBF, as specified in the table below. [Table 17]

[0204] If a joint chroma coding mode is selected, the QP for coding the joint chroma components is reduced by 1 (for modes 1 and 3) or 2 (for mode 2).

[0205] At the encoder side, a joint chroma residual is derived by corresponding downmixing of the Cb and Cr residuals. One of the three supported chroma coding modes is preselected based on minimizing the blending distortion (i.e., the distortion obtained by first downmixing the Cb and Cr residuals and then reconstructing or upmixing the Cb and Cr residuals from the joint chroma residual without quantization). Only the preselected mode is tested as a further mode in the mode decision process (i.e., using transform, quantization, and entropy coding). Due to the low-complexity preselection of one candidate mode for each TU, the encoding time remains substantially unchanged relative to JVET-M0305.

[0206] The tile group header syntax element indicating the sign (CSign) for deriving the second chroma component is determined by analyzing the correlation between high-pass filtered versions of the original Cb and Cr components for the tile group.

[0207] Joint Chroma Residual Coding Test CE7-2.1 / 2 discusses an extension of the joint chroma residual coding technique first described in JVET-M0305 by providing a wider range of joint coding parameters and modes. Specifically, the following are discussed:

[0208] 1) CE7-2.1: An extension of VTM5.0 by allowing three instead of one joint chroma coding mode, signaled using the chroma coded block flag (CBF) syntax element as in JVET-N0282 configuration 1. These coding modes apply a simplified cross-component rotation transform, as shown in Table 1.

[0209] 2) CE7-2.2: Same as CE7-2.1, but allows two joint chroma coding residual signals to be transmitted (instead of only one) in the case of joint chroma coding mode signaled via CBFCb=1, CBFCr=1. The rotation transform associated with this mode represents the Hadamard transform (see Table 2).

[0210] Canonical reconstruction of chroma residuals Thus, in contrast to M0305, which proposed the addition of one single-channel joint chroma residual coding mode (given by Cr = -Cb), the extension supports three modes for joint chroma residual coding with different blending factors. The modes are further characterized by the sign (i.e., the sign of the joint decoding weight, CSign, in JVET-N0282) used to derive the second chroma residual coded in the slice header. The use (activation) of the joint chroma coding mode is indicated by the TU-level flag tu_joint_cbcr_residual_flag, and the selected mode is implicitly indicated by the chroma CBF. The flag tu_joint_cbcr_residual_flag is present if either or both of the chroma CBFs for the TU are 1.

[0211] Similar to VTM5.0, a chroma QP offset (coded at the slice level) can be signaled specifically for use in a particular joint chroma coding mode. When the corresponding joint chroma coding mode (modes 2 and 4 in the following description) is active within a TU, this chroma QP offset is added to the chroma QP of the applied luma derivation during quantization and decoding of that TU. For other modes (modes 1 and 3 in the following description), the chroma QP is derived in the same way as for conventional Cb or Cr blocks.

[0212] An exemplary reconstruction process of the chroma residuals (resCb and resCr) from the transmitted transform blocks (resJointC, or resJointC1 and resJointC2 in CE7-2.2) is summarized in the table below. [Table 18]

[0213] Non-prescriptive determination of joint chroma residuals in encoders In the investigated encoder implementation, the joint chroma components are derived as follows: Depending on the mode (listed in the table above), resJointC{1,2} is generated by the encoder as follows:

[0214] If mode is equal to 4 (Hadamard transform, two residuals are transmitted), the joint residual is determined according to: resJointC1[x][y]=(resCb[x][y]+CSign*resCr[x][y]) / 2 resJointC2[x][y]=(resCb[x][y]-CSign*resCr[x][y]) / 2

[0215] Otherwise, if the mode is equal to 2 (single residual with reconstruction Cb=C, Cr=CSsign*C), the joint residual is determined according to: resJointC[x][y]=(resCb[x][y]+CSign*resCr[x][y]) / 2

[0216] Otherwise, if the mode is equal to 1 (single residual with reconstruction Cb=C, Cr=(CSign*C) / 2), the joint residual is determined according to: resJointC[x][y]=(4*resCb[x][y]+2*CSign*resCr[x][y]) / 5

[0217] Otherwise (mode equals 3, i.e., single residual, reconstruction Cr=C, Cb=(CSign*C) / 2), the joint residual is determined according to: resJointC[x][y]=(4*resCr[x][y]+2*CSign*resCb[x][y]) / 5

[0218] Further details on how the encoder selects the joint mode for a TU are given in Sec. 2.4 of JVET-N0282.

[0219] First embodiment of the present disclosure In the first embodiment of the present disclosure, the signaling of the PPS and slice header QP offset for the chrominance components is performed independently of each other according to the following table. [Table 19] [Table 20]

[0220] where pic_parameter_set_rbsp indicates the picture parameter set RBSP syntax, pps_cb_qp_offset and pps_cr_qp_offset specify the offsets to the luma quantization parameter Qp′Y used to derive Qp′Cb and Qp′Cr, respectively; The values ​​of pps_cb_qp_offset and pps_cr_qp_offset are in the range of -12 to +12, When sps_croma_format_idc is equal to 0, pps_cb_qp_offset and pps_cr_qp_offset are not used in the decoding process and the decoder shall ignore these values; When not present, the values ​​of pps_cb_qp_offset and pps_cr_qp_offset are inferred to be equal to 0, sps_joint_cbcr_enabled_flag equal to 1 specifies that joint coding of chroma residual is enabled for the coded layer video sequence (CLVS); sps_joint_cbcr_enabled_flag equal to 0 specifies that joint coding of chroma residual is disabled for CLVS, When not present, the value of sps_joint_cbcr_enabled_flag is inferred to be equal to 0. pps_joint_cbcr_qp_offset_value specifies the offset to the luma quantization parameter Qp'Y used to derive Qp'CbCr, The value of pps_joint_cbcr_qp_offset_value is in the range of -12 to +12.

[0221] In the prior art, the flag pps_slice_chroma_qp_offsets_present_flag is signaled in the PPS level syntax, which controls whether there are any further offsets signaled in the slice header, i.e., on the decoder side, the decoder needs to check the value of pps_slice_chroma_qp_offsets_present_flag to determine whether there are any further offsets signaled in the slice header. Compared to the prior art, in the first embodiment, the flag pps_slice_chroma_qp_offsets_present_flag is no longer signaled, in other words, there are always offsets signaled in the slice header, and therefore the decoder knows that there are further offsets signaled in the slice header without checking the value of pps_slice_chroma_qp_offsets_present_flag, in other words, both the PPS level syntax and the slice header syntax always include offsets. Therefore, decoding / signaling the chrominance QP offset in the slice header becomes easier.

[0222] Second embodiment of the present disclosure In the second embodiment of the present disclosure, the signaling of PPS and slice header QP offsets for chrominance components for JCCR mode and the signaling of SPS chroma mapping information for JCCR coding mode are performed depending on the SPS JCCR control flag according to the following table: For example, the sps JCCR control flag is sps_joint_cbcr_enabled_flag, which is signaled in the SPS level syntax (e.g., seq_parameter_set_rbsp syntax). [Table 21]

[0223] It can be seen that the value of "i" is determined based on the value of sps_joint_cbcr_enabled_flag, thus avoiding redundant signaling of JCCR syntax elements when the JCCR tool is disabled. [Table 22]

[0224] The signaling / decoding of pps_joint_cbcr_qp_offset depends on sps_joint_cbcr_enabled_flag, i.e., it can be recognized that pps_joint_cbcr_qp_offset is signaled or can be decoded only when the value of sps_joint_cbcr_enabled_flag is true (e.g., 1). Due to the conditional signaling of pps_joint_cbcr_qp_offset, less information needs to be signaled, thus saving resources. [Table 23]

[0225] It should be noted that sps_joint_cbcr_enabled_flag equal to 1 specifies that joint coding of chroma residuals is enabled for a coded layer video sequence (CLVS), sps_joint_cbcr_enabled_flag equal to 0 specifies that joint coding of chroma residuals is disabled for a coded layer video sequence, and when not present, the value of sps_joint_cbcr_enabled_flag is inferred to be equal to 0.

[0226] It should further be noted that seq_parameter_set_rbsp indicates the Raw Byte Sequence Payload (RBSP) syntax of the sequence parameter set, sps_num_points_in_qp_table_minus1[i] plus 1 specifies the number of points used to describe the i-th chroma QP mapping table, the value of sps_num_points_in_qp_table_minus1[i] ranges from 0 to 36, and when not present, the value of sps_num_points_in_qp_table_minus1[0] is inferred to be equal to 0.

[0227] The following is a description of the application of the encoding and decoding methods shown in the above embodiments and a system using them.

[0228] 6 is a block diagram showing a content delivery system 3100 for realizing a content distribution service. The content delivery system 3100 includes a capture device 3102, a terminal device 3106, and optionally a display 3126. The capture device 3102 communicates with the terminal device 3106 over a communication link 3104. The communication link may include the above-mentioned communication channel 13. The communication link 3104 includes, but is not limited to, WIFI, Ethernet, cable, wireless (3G / 4G / 5G), USB, or any combination thereof.

[0229] The capture device 3102 may generate data and encode the data using the encoding method described in the above embodiment. Alternatively, the capture device 3102 may deliver the data to a streaming server (not shown in the drawings), which then encodes the data and transmits the encoded data to the terminal device 3106. The capture device 3102 may include, but is not limited to, a camera, a smartphone or pad, a computer or laptop, a video conferencing system, a PDA, an in-vehicle device, or any combination thereof. For example, the capture device 3102 may include the source device 12 described above. When the data includes video, the video encoder 20 included in the capture device 3102 may actually perform video encoding processing. When the data includes audio (i.e., voice), the audio encoder included in the capture device 3102 may actually perform audio encoding processing. In some practical scenarios, the capture device 3102 delivers the encoded video and audio data by multiplexing them together. In other practical scenarios, for example, in a video conferencing system, the encoded audio data and the encoded video data are not multiplexed. The capture device 3102 delivers the encoded audio data and the encoded video data separately to the terminal device 3106 .

[0230] In the content delivery system 3100, a terminal device 3106 receives and plays encoded data. The terminal device 3106 may be a device capable of receiving and restoring data, such as a smartphone or pad 3108, a computer or laptop 3110, a network video recorder (NVR) / digital video recorder (DVR) 3112, a TV 3114, a set-top box (STB) 3116, a video conferencing system 3118, a video surveillance system 3120, a personal digital assistant (PDA) 3122, an in-vehicle device 3124, or any combination thereof, capable of decoding the encoded data. For example, the terminal device 3106 may include the destination device 14 described above. When the encoded data includes video, the video decoder 30 included in the terminal device is prioritized to perform video decoding. When the encoded data includes audio, the audio decoder included in the terminal device is prioritized to perform audio decoding.

[0231] In a terminal device having its own display, such as a smartphone or pad 3108, a computer or laptop 3110, a network video recorder (NVR) / digital video decoder (DVR) 3112, a TV 3114, a personal digital assistant (PDA) 3122 or an in-vehicle device 3124, the terminal device can provide the decoded data to its own display. In a terminal device without a display, such as an STB 3116, a video conferencing system 3118 or a video surveillance system 3120, an external display 3126 is brought into contact with it to receive and display the decoded data.

[0232] When each device in this system performs encoding or decoding, it can use a picture encoding device or a picture decoding device as shown in the above embodiment.

[0233] 7 is a diagram illustrating an example structure of the terminal device 3106. After the terminal device 3106 receives a stream from the capture device 3102, the protocol processing unit 3202 analyzes the transmission protocol of the stream. The protocol may include, but is not limited to, Real Time Streaming Protocol (RTSP), Hyper Text Transfer Protocol (HTTP), HTTP Live Streaming Protocol (HLS), MPEG-DASH, Real-time Transport Protocol (RTP), Real Time Messaging Protocol (RTMP), or any type of combination thereof.

[0234] After the protocol processing unit 3202 processes the stream, a stream file is generated. The file is output to the demultiplexing unit 3204. The demultiplexing unit 3204 can separate the multiplexed data into encoded audio data and encoded video data. As mentioned above, in some practical scenarios, for example, in a video conferencing system, the encoded audio data and encoded video data are not multiplexed. In this situation, the encoded data is sent to the video decoder 3206 and the audio decoder 3208 without passing through the demultiplexing unit 3204.

[0235] Through the demultiplexing process, a video elementary stream (ES), an audio ES, and optional subtitles are generated. A video decoder 3206, which includes the video decoder 30 as described in the above embodiment, decodes the video ES using the decoding method as shown in the above embodiment to generate video frames and supplies this data to a synchronization unit 3212. An audio decoder 3208 decodes the audio ES to generate audio frames and supplies this data to the synchronization unit 3212. Alternatively, the video frames may be stored in a buffer (not shown in FIG. 7) before being supplied to the synchronization unit 3212. Similarly, the audio frames may be stored in a buffer (not shown in FIG. 7) before being supplied to the synchronization unit 3212.

[0236] The synchronization unit 3212 synchronizes the video and audio frames and provides the video / audio to the video / audio display 3214. For example, the synchronization unit 3212 synchronizes the presentation of video and audio information. The information may be coded in the syntax using timestamps for the presentation of the coded audio and visual data and timestamps for the delivery of the data stream itself.

[0237] If subtitles are included in the stream, the subtitle decoder 3210 decodes the subtitles, synchronizes them with the video and audio frames, and provides the video / audio / subtitles to the video / audio / subtitle display 3216 .

[0238] The present invention is not limited to the above system, and either the picture encoding device or the picture decoding device in the above embodiments can be incorporated into other systems, for example, vehicle systems.

[0239] Furthermore, Figure 8 shows a flowchart of a method for inverse quantization of a current block of a picture, which is performed by a decoder, according to an embodiment of the present disclosure. In Figure 8, the method for inverse quantization of a current block of a picture, which is performed by a decoder, includes the following steps: (1601) receiving a bitstream; (1603) obtaining a joint chrominance component residual (JCCR) control flag from the bitstream; (1605) obtaining chrominance mapping information from the bitstream based on the JCCR control flag; (1607) obtaining at least one chrominance quantization parameter (QP) offset from the bitstream based on the JCCR control flag; (1609) obtaining a QP value for a current chrominance block based on the obtained chrominance mapping information and the at least one obtained chrominance QP offset; and (1611) performing inverse quantization on the current chrominance block by using the determined QP value. is shown to include

[0240] Furthermore, FIG. 9 shows a flowchart of a method for inverse quantization of a current block of a picture according to a further embodiment of the present disclosure, the method being performed by a decoder. In FIG. 9 , a method for inverse quantization of a current block of a picture, the method being performed by a decoder, is shown to include the following steps: (1651) receiving a bitstream, the bitstream including slice header syntax and PPS syntax; (1653) obtaining syntax elements from the PPS syntax, the obtained syntax elements including chrominance quantization parameter (QP) offsets; (1655) obtaining chrominance QP offset information from the slice header, the QP offset information being obtained independently from any PPS syntax elements in the PPS syntax; (1657) determining a QP value for the current chrominance block depending on the chrominance QP offset obtained from the PPS syntax and the chrominance QP offset information obtained from the slice header syntax; and (1659) performing inverse quantization on the current chrominance block using the determined QP value.

[0241] Furthermore, Figure 10 shows a flowchart of a method for inverse quantization of a current block of a picture, the method being performed by an encoder, according to an embodiment of the present disclosure. In Figure 10, the method for inverse quantization of a current block of a picture, the method being performed by an encoder, is shown to include the following steps: (2601) encoding a joint chrominance component residual (JCCR) control flag into a bitstream; (2603) encoding chrominance mapping information into the bitstream based on the JCCR control flag; (2605) encoding at least one chrominance quantization parameter (QP) offset into the bitstream based on the JCCR control flag; and (2067) providing a bitstream.

[0242] Furthermore, Figure 11 shows a flowchart of a method for inverse quantization of a current block of a picture according to the present disclosure, the method being performed by an encoder. In Figure 11, the method for inverse quantization of a current block of a picture, the method being performed by an encoder, includes the following steps: (2651) encoding syntax elements from a slice header and a PPS syntax into a bitstream, the syntax elements including a chrominance quantization parameter (QP) offset; (2653) encoding chrominance QP offset information from the slice header into the bitstream, the QP offset information being obtained independently from any PPS syntax element in the PPS syntax; and (2655) providing a bitstream. is shown to include

[0243] Further, Figure 12 illustrates a decoder 30 according to an embodiment of the present disclosure. The decoder 300 of Figure 12 includes: a receiving unit 3001 configured to receive a bitstream; a first obtaining unit 3003 configured to obtain a joint chrominance component residual (JCCR) control flag from the bitstream; a second obtaining unit 3005 configured to obtain chrominance mapping information from the bitstream based on the JCCR control flag; a third obtaining unit 3007 configured to obtain at least one chrominance quantization parameter (QP) offset from the bitstream based on the JCCR control flag; a fourth obtaining unit 3009 configured to obtain a QP value for a current chrominance block based on the obtained chrominance mapping information and the at least one obtained chrominance QP offset; and an inverse quantization unit (3011) configured to perform inverse quantization on the current chrominance block by using the determined QP value.

[0244] 13 illustrates a decoder 30 according to another embodiment of the present disclosure. The decoder 30 in FIG. 13 includes a receiving unit 3051 configured to receive a bitstream, the bitstream including a slice header syntax and a PPS syntax, and a first obtaining unit 3053 configured to obtain a syntax element from the PPS syntax, the obtained syntax element being a chrominance quantization parameter (QP, quantization a first obtaining unit 3053 including a chrominance QP offset (parameter) offset; a second obtaining unit 3055 configured to obtain chrominance QP offset information from a slice header, where the QP offset information is obtained independently from any PPS syntax element in the PPS syntax; a determining unit 3057 configured to determine a QP value for the current chrominance block depending on the chrominance QP offset obtained from the PPS syntax and the chrominance QP offset information obtained from the slice header syntax; and an inverse quantization unit 3059 configured to perform inverse quantization on the current chrominance block by using the determined QP value.

[0245] Further, Figure 14 illustrates an encoder 20 according to an embodiment of the present disclosure. The encoder 20 in Figure 14 includes a first encoding unit 2001 configured to encode a joint chrominance component residual (JCCR) control flag into a bitstream, a second encoding unit 2003 configured to encode chrominance mapping information into the bitstream based on the JCCR control flag, a third encoding unit 3005 configured to encode at least one chrominance quantization parameter (QP) offset into the bitstream based on the JCCR control flag, and a providing unit 3007 configured to provide the bitstream.

[0246] Furthermore, Figure 15 illustrates an encoder 20 according to another embodiment of the present disclosure. The encoder 20 of Figure 15 includes a first encoding unit 2051 configured to encode syntax elements from a slice header and a PPS syntax into a bitstream, where the syntax elements include a chrominance quantization parameter (QP) offset, a second encoding unit 2053 configured to encode chrominance QP offset information from the slice header into the bitstream, where the QP offset information is obtained independently from any PPS syntax element in the PPS syntax, and a providing unit 2055 configured to provide the bitstream.

[0247] Mathematical Operators The mathematical operators used in this application are similar to those used in the C programming language. However, the results of integer division and arithmetic shift operations are more precisely defined, and additional operators such as exponentiation and division of real values ​​are defined. Numbering and counting conventions generally start from 0, e.g., "first" is equivalent to 0th, "second" is equivalent to 1st, etc.

[0248] Logical operators The following logical operators are defined as follows: [Table 24]

[0249] Logical operators The following logical operators are defined as follows: x&&y The Boolean logic "product" of x and y x||y Boolean logic "union" of x and y Boolean logic "negation" x?y:z Evaluates to the value of y if x is true or not equal to 0, otherwise evaluates to the value of z

[0250] Relational operators The following relational operators are defined as follows: > greater than >= Greater than or equal to < Less than <= Less than or equal to == Equal != Not equal to When a relational operator is applied to a syntax element or variable that has been assigned the value "na" (not applicable), the value "na" is treated as a separate value of the syntax element or variable. The value "na" is considered not equal to any other value.

[0251] Bitwise Operators The following bitwise operators are defined as follows: & Bitwise "product". When operating on integer arguments, it operates on the two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than the other argument, the shorter argument is extended by appending the more significant bits equal to 0. Bitwise "sum". When operating on integer arguments, the operation is performed on the two's complement representation of the integer values. When operating on a binary argument that contains fewer bits than the other argument, the shorter argument is extended by appending the more significant bits equal to 0. ^ Bitwise "exclusive or". When operating on integer arguments, it operates on the two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than the other argument, the shorter argument is extended by appending more significant bits equal to 0. x>>y Arithmetic right shift of the two's complement integer representation of x by y binary digits. This function is defined only for non-negative integer values ​​of y. The bit shifted into the most significant bit (MSB) of the right shift result has a value equal to the MSB of x before the shift operation. x << y Arithmetic left shift of the two's complement integer representation of x by y binary digits. This function is only defined for non-negative integer values of y. The bit shifted into the least significant bit (LSB) as a result of the left shift has a value equal to 0.

[0252] Assignment operators The following assignment operators are defined as follows. = Assignment operator ++ Increment. That is, x++ is equal to x = x + 1. When used in an array index, it is evaluated to the value of the variable before the increment operation. -- Decrement. That is, x-- is equal to x = x - 1. When used in an array index, it is evaluated to the value of the variable before the decrement operation. += Increment by the specified amount. That is, x += 3 is equal to x = x + 3, and x += (-3) is equal to x = x + (-3). -= Decrement by the specified amount. That is, x -= 3 is equal to x = x - 3, and x -= (-3) is equal to x = x - (-3).

[0253] Range notation The following notations are used to specify a range of values. x = y..z x takes integer values greater than or equal to y and less than or equal to z, where x, y, and z are integers and z is greater than y.

[0254] Mathematical functions The following mathematical functions are defined.

Number

number

number

number

number

number

number

[0255] Operation precedence When the precedence of an expression is not explicitly indicated by the use of parentheses, the following rules apply: An operation with a higher priority is evaluated before any operation with a lower priority. -Operations of equal precedence are evaluated sequentially from left to right.

[0256] The table below specifies the priority of operations from highest to lowest, with higher positions in the table indicating higher priority.

[0257] For operators that are also used in the C programming language, the precedence used herein is the same as the precedence used in the C programming language. [Table 25]

[0258] Text description of logical operations In text, the following format: if(condition 0) Statement 0 else(condition 1) Statement 1 ... else / *Reference notes for remaining conditions* / Statement n A statement of logical operation such as mathematically described in may be written in the following manner: ...as / ...the following applies: -If condition 0, then statement 0 - Otherwise, if condition 1, then statement 1 -... - Otherwise (reference notes for the remaining conditions), statement n Each "if... otherwise, if... otherwise" statement in the text is introduced by "as" or "the following applies" immediately followed by "if...". The final condition of an "if... otherwise, if... otherwise, if..." is always "otherwise". Alternating "if... otherwise, if... otherwise, if..." statements can be identified by matching the "as" or "the following applies" that ends with "otherwise".

[0259] In text, the following format: if(condition0a&&condition0b) Statement 0 else if(condition 1a||condition 1b) Statement 1 ... else Statement n A statement of logical operation such as mathematically described in may be written in the following manner: ...as / ...the following applies: -Statement 0 if all of the following conditions are true: -Condition 0a -condition 0b - Otherwise, if one or more of the following conditions are true, then statement 1: -Condition 1a -Condition 1b -… - Otherwise, statement n

[0260] In text, the following format: if(condition 0) Statement 0 if(condition1) Statement 1 A statement of logical operation such as mathematically described in may be written in the following manner: If condition 0, then statement 0 If condition 1 is true, then statement 1

[0261] Although embodiments of the present invention have been described primarily in the context of video coding, it should be noted that embodiments of coding system 10, encoder 20 and decoder 30 (and correspondingly system 10), as well as other embodiments described herein, may also be configured for still picture processing or coding, i.e., processing or coding of individual pictures independent of any previous or subsequent pictures, as in video coding. In general, when picture processing coding is limited to a single picture 17, only inter prediction units 244 (encoder) and 344 (decoder) may not be available. All other functions (also called tools or techniques) of the video encoder 20 and the video decoder 30 may be equally used for still image picture processing, e.g., residual calculation 204 / 304, transform 206, quantization 208, inverse quantization 210 / 310, (inverse) transform 212 / 312, partitioning 262 / 362, intra prediction 254 / 354, and / or loop filtering 220, 320, as well as entropy coding 270 and entropy decoding 304.

[0262] For example, embodiments of the encoder 20 and the decoder 30, and the functions described herein with respect to the encoder 20 and the decoder 30, may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium or transmitted over a communication medium as one or more instructions or code and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which correspond to tangible media such as data storage media, or communication media, including any medium that facilitates transfer of a computer program from one place to another, for example, according to a communication protocol. Thus, computer-readable media may generally correspond to (1) tangible computer-readable storage media that are non-transitory, or (2) communication media such as a signal or carrier wave. Data storage media may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, code, and / or data structures for implementing the techniques described in this disclosure. A computer program product may include a computer-readable medium.

[0263] By way of example, and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Additionally, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but instead cover non-transitory tangible storage media. As used herein, disk and disc include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs reproduce data optically with a laser. Combinations of the above should also be included within the scope of computer-readable media.

[0264] The instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term "processor," as used herein, may refer to any of the above structures or any other structure suitable for implementing the techniques described herein. Furthermore, in some aspects, the functionality described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or may be incorporated into a combined codec. Furthermore, the techniques may be implemented entirely in one or more circuit or logic elements.

[0265] The techniques of this disclosure may be implemented in a wide range of devices or apparatuses, including a wireless handset, an integrated circuit (IC), or a set of ICs (e.g., a chipset). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the techniques of the disclosure, but do not necessarily require implementation by different hardware units. Rather, as noted above, the various units may be combined with a codec hardware unit in combination with appropriate software and / or firmware, or may be provided by a collection of interoperating hardware units including one or more processors as described above.

[0266] The present disclosure provides the following 19 additional aspects.

[0267] A first aspect of a method for inverse quantization of a current block of a picture, the method being performed by a decoder, the method comprising: receiving a bitstream, the bitstream including a slice header syntax and a PPS syntax; obtaining a syntax element from the PPS syntax, the obtained syntax element including a chrominance quantization parameter (QP) offset; obtaining chrominance QP offset information from a slice header, the QP offset information being obtained independently from any PPS syntax element in the PPS syntax; determining a QP value for the current chrominance block depending on the chrominance QP offset obtained from the PPS syntax and the chrominance QP offset information obtained from the slice header syntax; performing inverse quantization on the current chrominance block using the determined QP value; A first aspect of the method includes:

[0268] A second aspect of the method according to the first aspect, wherein the at least one chrominance QP offset obtained from the PPS syntax includes pps_cb_qp_offset, pps_cr_qp_offset, pps_joint_cbcr_qp_offset, and cu_chroma_qp_offset_enabled_flag.

[0269] In a third aspect of the method according to the second aspect, when the value of cu_chroma_qp_offset_enabled_flag is true (e.g., when the value of cu_chroma_qp_offset_enabled_flag is 1), the chrominance QP offsets obtained from the PPS syntax further include cu_chroma_qp_offset_subdiv, chroma_qp_offset_list_len_minus1, cb_qp_offset_list[i], cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i];

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[0270] A fourth aspect of the method according to any one of the first to third aspects, wherein the chrominance QP offset information obtained from the slice header syntax includes slice_cb_qp_offset and slice_cr_qp_offset.

[0271] A fifth aspect of the method according to the fourth aspect, wherein when the value of sps_joint_cbcr_enabled_flag (e.g., an element of the SPS level syntax included in the bitstream) is true (e.g., the value of sps_joint_cbcr_enabled_flag is 1), the chrominance QP offset information obtained from the slice header syntax further includes slice_joint_cbcr_qp_offset.

[0272] A sixth aspect of the method according to any one of the first to fifth aspects, wherein the PPS syntax comprises the following structure: [Table 26]

[0273] A seventh aspect of the method according to any one of the first to sixth aspects, wherein the slice header syntax includes the following structure: [Table 27]

[0274] An eighth aspect of the method according to any one of the first to seventh aspects, wherein the flag pps_slice_chroma_qp_offsets_present_flag is omitted in the PPS syntax, or An eighth aspect of the method, wherein the slice header and PPS syntax always include an element related to a chrominance QP offset.

[0275] A ninth aspect of a method for inverse quantization of a current block of a picture, the method being performed by a decoder, the method comprising: receiving a bitstream; obtaining a joint chrominance component residual (JCCR) control flag from the bitstream; obtaining chrominance mapping information from the bitstream based on a JCCR control flag; obtaining a chrominance quantization parameter (QP) offset from the bitstream based on a JCCR control flag; obtaining a QP value for the current chrominance block based on the obtained chrominance mapping information and the obtained chrominance QP offset; performing inverse quantization on the current chrominance block using the determined QP value; A ninth aspect of the method, comprising:

[0276] A tenth aspect of the method according to the ninth aspect, wherein the bitstream includes an SPS level syntax and the JCCR control flag is obtained from the SPS level syntax.

[0277] An eleventh aspect of the method according to the ninth or tenth aspect, wherein the JCCR control flag is sps_joint_cbcr_enabled_flag.

[0278] A twelfth aspect of the method according to any one of the ninth to eleventh aspects, wherein the chrominance mapping information includes delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and the chrominance mapping information is obtained from SPS level syntax included in the bitstream.

[0279] A thirteenth aspect of the method according to any one of the ninth to twelfth aspects, wherein the SPS level syntax comprises the following structure: [Table 28]

[0280] A fourteenth aspect of the method according to any one of the ninth to thirteenth aspects, wherein the step of obtaining a chrominance QP offset from the bitstream based on a JCCR control flag comprises: A fourteenth aspect of a method, comprising obtaining a chrominance QP offset from a PPS level syntax of the bitstream based on a JCCR control flag.

[0281] A fifteenth aspect of the method according to any one of the ninth to fourteenth aspects, wherein the PPS level syntax comprises the following structure: [Table 29]

[0282] A sixteenth aspect of a decoder including a processing circuit for performing the method according to any one of the first to fifteenth aspects.

[0283] A seventeenth aspect of a computer program product comprising program code for, when executed on a computer or processor, performing a method according to any one of the preceding aspects.

[0284] An eighteenth aspect of a decoder, comprising: one or more processors; a non-transitory computer-readable storage medium coupled to the processor and storing programming for execution by the processor; An eighteenth aspect of a decoder, comprising the programming, when executed by a processor, to configure the decoder to perform a method according to any one of the above aspects.

[0285] A nineteenth aspect of a non-transitory computer-readable medium carrying program code, comprising: A nineteenth aspect of a non-transitory computer-readable medium, wherein program code, when executed by a computing device, causes the computing device to perform a method according to any one of the preceding aspects.

Claims

1. 1. A method for inverse quantization of a current block of a picture, the method being performed by a decoder, the method comprising: receiving a bitstream; obtaining a joint chrominance component residual (JCCR) control flag from the bitstream; obtaining chrominance mapping information from the bitstream based on the JCCR control flag; obtaining at least one chrominance quantization parameter (QP) offset from the bitstream based on the JCCR control flag; obtaining a QP value for the current chrominance block based on the obtained chrominance mapping information and the at least one obtained chrominance QP offset; performing inverse quantization on the current chrominance block using the determined QP value; A method comprising:

2. The method of claim 1 , wherein the bitstream includes an SPS level syntax, and the JCCR control flag is obtained from the SPS level syntax.

3. The method of claim 1 or 2, wherein the JCCR control flag is the sps_joint_cbcr_enabled_flag.

4. The method of claim 3 , wherein if the value of the sps_joint_cbcr_enabled_flag is 1, the at least one obtained chrominance QP offset is specified by slice_joint_cbcr_qp_offset.

5. 5. The method of claim 1, wherein the chrominance mapping information comprises delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and the chrominance mapping information is obtained from an SPS level syntax included in the bitstream.

6. The method of claim 2 , wherein the SPS level syntax includes the following structure: Table 30

7. The step of obtaining the at least one chrominance QP offset from the bitstream based on the JCCR control flag includes:

7. The method of claim 1, further comprising obtaining the at least one chrominance QP offset from a Picture Parameter Set (PPS) level syntax of the bitstream based on the JCCR control flag.

8. The method of claim 7 , wherein the PPS level syntax includes the following structure: Table 31

9. 1. A method for inverse quantization of a current block of a picture, the method being performed by a decoder, the method comprising: receiving a bitstream, the bitstream including a slice header syntax and a PPS syntax; obtaining a syntax element from the PPS syntax, the obtained syntax element including at least one chrominance quantization parameter (QP) offset; obtaining chrominance QP offset information from the slice header, wherein the QP offset information is obtained independently from any PPS syntax element in the PPS syntax; determining a QP value for the current chrominance block depending on the at least one chrominance QP offset obtained from the PPS syntax and the chrominance QP offset information obtained from the slice header syntax; performing inverse quantization on the current chrominance block using the determined QP value; A method comprising:

10. 1. A method for encoding a current block of a picture, the method being performed by an encoder, the method comprising: encoding a joint chrominance component residual (JCCR) control flag into the bitstream; encoding chrominance mapping information into the bitstream based on the JCCR control flag; encoding at least one chrominance quantization parameter (QP) offset into the bitstream based on the JCCR control flag; providing the bitstream; A method comprising:

11. The method of claim 10 , wherein the bitstream includes an SPS level syntax, and the JCCR control flag is encoded into the SPS level syntax.

12. The method according to claim 10 or 11, wherein the JCCR control flag is the sps_joint_cbcr_enabled_flag.

13. The method of claim 12 , wherein if the value of the sps_joint_cbcr_enabled_flag is 1, the at least one coded chrominance QP offset is specified by slice_joint_cbcr_qp_offset.

14. 14. The method of claim 10, wherein the chrominance mapping information comprises delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and the chrominance mapping information is coded into an SPS level syntax included in the bitstream.

15. 15. The method of claim 10, wherein the SPS level syntax includes the following structure: Table 32

16. encoding the at least one chrominance QP offset into the bitstream based on the JCCR control flag, 16. The method of claim 10, further comprising encoding the at least one chrominance QP offset into a Picture Parameter Set (PPS) level syntax of the bitstream based on the JCCR control flag.

17. 17. The method of claim 16, wherein the PPS level syntax includes the following structure: Table 33

18. 1. A method for encoding a current block of a picture, the method being performed by an encoder, the method comprising: encoding syntax elements of a PPS syntax into a bitstream, the syntax elements including at least one chrominance quantization parameter (QP) offset; encoding chrominance QP offset information from slice header syntax into the bitstream, wherein the QP offset information is encoded independently from any PPS syntax elements in the PPS syntax; providing the bitstream; A method comprising:

19. A decoder (30) including processing circuitry for carrying out the method of any one of claims 1 to 9.

20. An encoder (20) including processing circuitry for carrying out the method of any one of claims 10 to 18.

21. A computer program product comprising program code for performing the method of any one of claims 1 to 18 when the computer program product is run on a computer or processor.

22. A decoder comprising: one or more processors; a non-transitory computer-readable storage medium coupled to the processor and storing programming for execution by the processor; 10. A decoder comprising: a decoder programmable for decoding a signal from a plurality of inputs; a decoder programmable for decoding a signal from a plurality of inputs;

23. 1. An encoder comprising: one or more processors; a non-transitory computer-readable storage medium coupled to the processor and storing programming for execution by the processor; 20. An encoder comprising: a processor configured to execute a method according to any one of claims 10 to 18, the processor being configured to execute a method according to any one of claims 10 to 18.

24. A non-transitory computer readable medium carrying program code, comprising: A non-transitory computer readable medium, the program code, when executed by a computing device, causing the computing device to perform the method of any one of claims 1 to 18.

25. A decoder (30), a receiving unit configured to receive a bitstream; a first obtaining unit configured to obtain a joint chrominance component residual (JCCR) control flag from the bitstream; a second obtaining unit configured to obtain chrominance mapping information from the bitstream based on the JCCR control flag; a third obtaining unit configured to obtain at least one chrominance quantization parameter (QP) offset from the bitstream based on the JCCR control flag; a fourth obtaining unit configured to obtain a QP value for the current chrominance block based on the obtained chrominance mapping information and the at least one obtained chrominance QP offset; an inverse quantization unit configured to perform inverse quantization on the current chrominance block by using the determined QP value; a decoder (30) including:

26. 26. The decoder of claim 25, wherein the bitstream includes an SPS level syntax, and the JCCR control flag is obtained from the SPS level syntax.

27. 27. A decoder according to claim 25 or 26, wherein the JCCR control flag is the sps_joint_cbcr_enabled_flag.

28. 28. The decoder of claim 27, wherein if the value of the sps_joint_cbcr_enabled_flag is 1, the at least one obtained chrominance QP offset is specified by slice_joint_cbcr_qp_offset.

29. 29. A decoder according to any one of claims 25 to 28, wherein the chrominance mapping information comprises delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and wherein the chrominance mapping information is obtained from an SPS level syntax included in the bitstream.

30. 30. A decoder according to any one of claims 26 to 29, wherein the SPS level syntax comprises the following structure: Table 34

31. Obtaining the at least one chrominance QP offset from the bitstream based on the JCCR control flag includes:

31. The decoder of claim 25, further comprising obtaining the at least one chrominance QP offset from a Picture Parameter Set (PPS) level syntax of the bitstream based on the JCCR control flag.

32. 32. The decoder of claim 31 , wherein the PPS level syntax includes the following structure: Table 35

33. A decoder (30), a receiving unit configured to receive a bitstream, the bitstream including a slice header syntax and a PPS syntax; a first obtaining unit configured to obtain a syntax element from the PPS syntax, the obtained syntax element including a chrominance quantization parameter (QP) offset; a second acquisition unit configured to acquire chrominance QP offset information from the slice header, wherein the QP offset information is acquired independently from any PPS syntax element in the PPS syntax; a determining unit configured to determine a QP value for the current chrominance block depending on the chrominance QP offset obtained from the PPS syntax and the chrominance QP offset information obtained from the slice header syntax; an inverse quantization unit configured to perform inverse quantization on the current chrominance block by using the determined QP value; a decoder (30) including:

34. An encoder (20), a first encoding unit configured to encode a joint chrominance component residual (JCCR) control flag into a bitstream; a second encoding unit configured to encode chrominance mapping information into the bitstream based on the JCCR control flag; a third encoding unit configured to encode at least one chrominance quantization parameter (QP) offset into the bitstream based on the JCCR control flag; a providing unit configured to provide the bitstream; an encoder (20) including:

35. 35. The encoder of claim 34, wherein the bitstream includes an SPS level syntax, and the JCCR control flag is encoded into the SPS level syntax.

36. 36. An encoder according to claim 33 or 35, wherein the JCCR control flag is the sps_joint_cbcr_enabled_flag.

37. 37. The encoder of claim 36, wherein if the value of the sps_joint_cbcr_enabled_flag is 1, the at least one coded chrominance QP offset is specified by slice_joint_cbcr_qp_offset.

38. 38. An encoder according to any one of claims 33 to 37, wherein the chrominance mapping information comprises delta_qp_in_val_minus1[i][j] and delta_qp_out_val[i][j], and wherein the chrominance mapping information is coded into an SPS level syntax included in the bitstream.

39. 39. The encoder of any one of claims 33 to 38, wherein the SPS level syntax includes the following structure: Table 36

40. encoding the at least one chrominance QP offset into the bitstream based on the JCCR control flag, 40. The encoder of claim 33, further comprising encoding the at least one chrominance QP offset into a Picture Parameter Set (PPS) level syntax of the bitstream based on the JCCR control flag.

41. 41. The encoder of claim 40, wherein the PPS level syntax includes the following structure: Table 37

42. An encoder (20), a first encoding unit configured to encode syntax elements from a slice header and a PPS syntax into the bitstream, the syntax elements including a chrominance quantization parameter (QP) offset; a second encoding unit configured to encode chrominance QP offset information of the slice header syntax into the bitstream, wherein the QP offset information is obtained independently from any PPS syntax element in the PPS syntax; and a providing unit configured to provide the bitstream; an encoder (20) including:

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