Apparatus, method and computer program for video

Abstract

A method comprising: acquiring a video signal comprising a block of a video frame, the block comprising a plurality of pixels (500); acquiring information indicating reconstruction or visibility with respect to the pixels in the block at the time of decoding (502); and disabling in-loop filtering (504) for such a block having only a subset of pixels that will be reconstructed or visible at decoding based on the information indicating reconstruction or visibility of the pixels in the block.

Description

TECHNICAL FIELD

[0001] The present invention relates to an apparatus, method and computer program for video coding. BACKGROUND

[0002] Video frames representing content can be provided with an accompanying reconstruction signal that is used to control the reconstruction or visibility of parts or even individual pixels of the frame at decoding time. One example of such an accompanying reconstruction signal is the occupancy picture (also known as occupancy map or occupancy component) used in MPEG-based volumetric video coding (V3C). The occupancy component is able to inform a V3C decoding and / or rendering system which samples in the 2D component are associated with data in the final 3D representation. Another example is the alpha channel (also known as alpha matte) that provides an alpha value defining the transparency level of parts or even individual pixels of the frame.

[0003] Modern video codecs make use of in-loop filtering to reduce coding artefacts caused, for example, by quantized transform coefficients. In-loop filters such as deblocking filter (DBF), adaptive loop filter (ALF), sample adaptive offset (SAO) perform well on traditional 2D video content.

[0004] However, for video content provided with an accompanying reconstruction signal, when applied to areas not intended for reconstruction, for example, areas in the geometry video and attribute video for V3C video whose corresponding occupancy map video area is set to 0, or areas of an alpha matte set to full transparency, such filtering can result in unwanted distortion and reduced coding efficiency. SUMMARY

[0005] Now, an improved method and technical devices implementing the method have been invented by which the above-mentioned problems can be mitigated. Various aspects include methods, apparatuses and computer programs or computer readable media having stored therein signals comprising the computer programs, characterized by what is stated in the independent claims. Various details of embodiments are disclosed in the dependent claims and in the corresponding images and descriptions.

[0006] The scope of protection sought for various embodiments of the present invention is defined by the appended independent claims. The embodiments and features mentioned in the specification, if any, that are not covered by the independent claims should be interpreted as examples helpful for understanding the invention.

[0007] According to a first aspect, there is provided an apparatus comprising: means for obtaining a video signal, the video signal comprising a block of video frames, the block comprising a plurality of pixels; means for obtaining information indicative of a reconstruction or visibility of the pixels in the block at decoding time; and means for disabling, based on the information indicative of a reconstruction or visibility of the pixels in the block, in-loop filtering for the block having only a subset of pixels that will be reconstructed or visible at decoding time.

[0008] According to an embodiment, the information indicative of a reconstruction or visibility of the pixels in the block at decoding time is one or more of: - an occupancy map video; - an occupancy signal; - an alpha map video; - an alpha channel.

[0009] According to an embodiment, the block is one of: a coding unit (CU), a prediction unit (PU), a transform unit (TU), a coding tree unit (CTU), a slice, or a sub-picture.

[0010] According to an embodiment, the apparatus comprises means for excluding, in the filter parameter derivation stage, samples corresponding to pixels that do not become reconstructed or visible at decoding time.

[0011] According to an embodiment, the apparatus comprises means for including, in the filter parameter derivation stage, only samples corresponding to pixels that are reconstructed or become visible and non-visible in a boundary region of the pixels at decoding time.

[0012] According to an embodiment, the apparatus comprises means for adjusting a filter strength for samples corresponding to pixels that are reconstructed or become visible and non-visible in the boundary region of the pixels at decoding time.

[0013] According to an embodiment, the apparatus comprises means for computing a dedicated filter class for blocks comprising pixels that become both visible and non-visible at decoding time.

[0014] According to an embodiment, the apparatus comprises means for using only a subset of in-loop filters for blocks comprising pixels that become visible.

[0015] According to an embodiment, the apparatus comprises means for applying a combination of in-loop filters on a block-by-block and / or pixel-by-pixel basis.

[0016] According to an embodiment, the apparatus comprises means for completely or partially deactivating one or more in-loop filters for blocks comprising only pixels that do not become visible at decoding time.

[0017] According to an embodiment, the apparatus comprises means for signaling, in or with a bitstream comprising the video signal, one or more parameters regarding the applicability of in-loop filters.

[0018] According to an embodiment, the apparatus comprises means for implementing the signaling in a video parameter set raw byte sequence payload (RBSP) syntax or a sequence parameter set raw byte sequence payload (RBSP) syntax, wherein the signaling comprises a flag indicating the activation of the guided in-loop filtering.

[0019] An apparatus according to a second aspect comprises at least one processor and at least one memory, the at least one memory having computer program stored thereon, the at least one memory and the computer program configured to, with the at least one processor, cause the apparatus at least to perform: obtaining a video signal comprising a block of a video frame, the block comprising a plurality of pixels; obtaining information indicating a reconstruction or visibility regarding the pixels in the block at decoding time; and based on the information indicating a reconstruction or visibility regarding the pixels in the block, disabling in-loop filtering for the block having only a subset of pixels that will be reconstructed or visible at decoding time.

[0020] A method according to a third aspect comprises: obtaining a video signal comprising a block of a video frame, the block comprising a plurality of pixels; obtaining information indicating a reconstruction or visibility regarding the pixels in the block at decoding time; and based on the information indicating a reconstruction or visibility regarding the pixels in the block, disabling in-loop filtering for the block having only a subset of pixels that will be reconstructed or visible at decoding time.

[0021] An apparatus according to a fourth aspect comprises: means for receiving a bitstream comprising an encoded video signal, the encoded video signal comprising a block of a video frame, the block comprising a plurality of pixels; means for receiving, in or with the bitstream, information indicating a reconstruction or visibility regarding the pixels in the block; and means for decoding the encoded video signal based on at least the information indicating a reconstruction or visibility regarding the pixels in the block by disabling in-loop filtering for the block having only a subset of pixels that will be reconstructed or visible.

[0022] An apparatus according to a fifth aspect comprises at least one processor and at least one memory, said at least one memory having computer program stored thereon, the at least one memory and the computer program configured to, with the at least one processor, cause the apparatus at least to perform: receiving a bitstream, the bitstream comprising an encoded video signal, the encoded video signal comprising a block of a video frame, the block comprising a plurality of pixels; receiving, in or with the bitstream, information indicative of a reconstruction or visibility with respect to the pixels in the block; and decoding the encoded video signal according to at least the information indicative of a reconstruction or visibility with respect to the pixels in the block by disabling in-loop filtering for the block having only a subset of pixels to be reconstructed or visible.

[0023] A method according to a sixth aspect comprises: receiving a bitstream, the bitstream comprising an encoded video signal, the encoded video signal comprising a block of a video frame, the block comprising a plurality of pixels; receiving, in or with the bitstream, information indicative of a reconstruction or visibility with respect to the pixels in the block; and decoding the encoded video signal according to at least the information indicative of a reconstruction or visibility with respect to the pixels in the block by disabling in-loop filtering for the block having only a subset of pixels to be reconstructed or visible.

[0024] A computer readable storage medium according to another aspect comprises code for use by an apparatus, which when executed by a processor, causes the apparatus to perform the above method. BRIEF DESCRIPTION OF DRAWINGS

[0025] For a more complete understanding of example embodiments, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:

[0026] Figure 1a and 1b An encoder and decoder for encoding and decoding 2D pictures are shown;

[0027] Figure 2 An example of an in-loop filter chain in a CCV is shown;

[0028] Figure 3a and 3b Compression and decompression processes for V3C volumetric video are shown;

[0029] Figure 4 Examples of different stages of reconstructing a V3C encoded volumetric video are shown;

[0030] Figure 5 A flowchart for a sending / encoding method according to an embodiment is shown;

[0031] Figure 6 Examples of different states for encoding a coding unit according to occupancy information are shown;

[0032] Figure 7 A flowchart is shown for a receiving / decoding method according to an embodiment. DETAILED DESCRIPTION

[0033] A video codec comprises an encoder that transforms an input video into a compressed representation suitable for storage / transmission, and a decoder that can decompress the compressed video representation back into a viewable form. The encoder can discard some information in the original video sequence in order to represent the video in a more compact form, i.e. at a lower bit rate.

[0034] Figure 1a and 1b An encoder and decoder for encoding and decoding 2D pictures are shown. A video codec comprises an encoder that transforms an input video into a compressed representation suitable for storage / transmission, and a decoder that can decompress the compressed video representation back into a viewable form. Typically, the encoder discards and / or loses some information in the original video sequence in order to represent the video in a more compact form, i.e. at a lower bit rate. Figure 1a An example of an encoding process is illustrated in the middle. Figure 1a An image (I n ) to be encoded is shown; a predicted representation of the image block (P ’n ); a prediction error signal (D n ); a reconstructed prediction error signal (D ’n ); a preliminary reconstructed image (I ’n ); a final reconstructed image (R ’n ); a transform (T) and inverse transform (T -1 ); quantization (Q) and inverse quantization (Q -1 ); entropy encoding (E); a reference frame memory (RFM); inter prediction (P inter ); intra prediction (P intra ); mode selection (MS) and filtering (F).

[0035] Figure 1b An example of a decoding process is illustrated. Figure 1b A predicted representation of the image block (P ’n ); a reconstructed prediction error signal (D ’n ); a preliminary reconstructed image (I ’n ); a final reconstructed image (R ’n ); an inverse transform (T -1 ); inverse quantization (Q -1 ); entropy decoding (E -1 ); a reference frame memory (RFM); prediction (inter or intra) (P) and filtering (F) are shown.

[0036] Many hybrid video encoders (e.g., ITU-T H.263, H.264 / AVC, HEVC, and VCC) encode video information in two stages. First, pixel values in a certain picture region (or block) are predicted, e.g., by a motion compensation component that finds and indicates a region in a previously encoded video frame that closely corresponds to the block being encoded, or by a spatial component that uses pixel values of the surrounding of the block being encoded in a certain way. Second, the prediction error, i.e., the difference between the predicted pixel block and the original pixel block, is encoded. This is typically done by transforming the difference in pixel values using a certain transform (e.g., a discrete cosine transform (DCT) or a variant thereof), quantizing the coefficients, and entropy encoding the quantized coefficients. By varying the fidelity of the quantization process, the encoder can control the balance between the accuracy of the pixel representation (picture quality) and the size of the resulting encoded video representation (file size or transmission bitrate). Video codecs can also provide a transform skip mode that the encoder can choose to use. In transform skip mode, the prediction error is encoded in the sample domain, e.g., by deriving sample-wise differences with respect to certain neighboring samples and encoding the sample-wise differences with an entropy encoder.

[0037] Many video encoders divide pictures into blocks together with a grid of blocks. For example, in the High Efficiency Video Coding (HEVC) standard, the following partitioning and definitions are used. A coding block can be defined as an NxN block of samples for a certain value of N, such that a coding tree block is partitioned into coding blocks, which is a type of partitioning. A coding tree block (CTB) can be defined as an NxN block of samples for a certain value of N, such that a component is partitioned into coding tree blocks, which is a type of partitioning. A coding tree unit (CTU) can be defined as a coding tree block of luma samples, two corresponding coding tree blocks of chroma samples of a picture having three sample arrays, or a coding tree block of samples of a monochrome picture or a picture that is coded using three separate color planes and syntax structures for coding samples. A coding unit (CU) can be defined as a coding block of luma samples, two corresponding coding blocks of chroma samples of a picture having three sample arrays, or a coding block of samples of a monochrome picture or a picture that is coded using three separate color planes and syntax structures for coding samples. A CU having the maximum allowed size can be referred to as an LCU (largest coding unit) or coding tree unit (CTU), and a video picture is divided into non-overlapping LCUs.

[0038] In HEVC, a picture can be divided into tiles, which are rectangular and comprise an integer number of LCUs. In HEVC, the division into tiles forms a regular grid, where the height and width of a tile differ from each other by at most one LCU. In HEVC, a slice is defined as an integer number of coding tree units, which is contained in one independent slice segment and all subsequent dependent slice segments, if any, before the next independent slice segment, if any, within the same access unit. In HEVC, a slice segment is defined as an integer number of coding tree units that are consecutively ordered in the tile scan and contained in a single NAL unit. The division of each picture into slice segments is a form of partitioning. In HEVC, an independent slice segment is defined as a slice segment whose values of some syntax elements of the slice header are not inferred from those of a previous slice segment, and a dependent slice segment is defined as a slice segment whose values of some syntax elements of the slice header are inferred in decoding order from those of a previous independent slice segment. In HEVC, a slice header is defined as the slice segment header of the independent slice segment that is the current slice segment, or the slice segment header of the independent slice segment that precedes the current dependent slice segment, and a slice segment header is defined as the portion of the coded slice segment that contains data elements belonging to the first coding tree unit or all coding tree units represented in the slice segment. If a tile is not used, the CUs are scanned in the raster scan order of the LCUs within the tile or within the picture. Within a LCU, the CUs have a specific scan order.

[0039] Entropy encoding / decoding can be performed in many ways. For example, context-based encoding / decoding can be used, in which both the encoder and the decoder modify the context state of the encoding parameters based on previously encoded / decoded encoding parameters. The context-based encoding can for example be context adaptive binary arithmetic coding (CABAC) or context adaptive variable length coding (CAVLC) or any similar entropy coding. The entropy encoding / decoding can alternatively or additionally be performed using a variable length coding scheme, such as Huffman encoding / decoding or Exp-Golomb encoding / decoding. The decoding of the encoding parameters from the entropy encoded bitstream or codewords can be referred to as parsing.

[0040] The purpose of in-loop filtering is to reduce artifacts and distortions that can occur during the compression process. Compression techniques such as block-based motion compensation and discrete cosine transform (DCT) can introduce artifacts such as blocking, ringing, and blurring in the decoded video. In-loop filtering is designed to reduce these artifacts and improve the perceived visual quality of the video.

[0041] In-loop filtering plays a key role in the maintenance of compressed video quality, as it can not only improve the quality of the current frame, but also provide higher quality references for subsequent frames. Figure 2In-loop filters in VCC are depicted. Four processing steps, i.e. luma mapping and chroma scaling (LMCS) processing, followed by a deblocking filter (DBF), a SAO filter, and an adaptive loop filter (ALF), are applied to the reconstructed samples before they are written into the decoded picture buffer. DBF and SAO are similar to those in the HEVC standard, whereas LMCS and ALF are newly introduced in VCC.

[0042] In VCC, in-loop filtering consists of a fixed order chain of three filters, including a deblocking filter (DBF), a sample adaptive offset (SAO) filter, and an adaptive loop filter (ALF). A block-based ALF is used in VCC, which includes luma ALF, chroma ALF, and cross-component ALF (CC-ALF). ALF filter coefficients are either predefined and fixed in both encoder and decoder, or adaptively signaled on a picture basis using an adaptation parameter set (APS). To enable merging of sub-picture bitstreams (encoded using independent encoder instances) into a single VVC-compliant picture without any ALF-APS identifier collision problem, the following solutions have been proposed: - Solution 1 (disable ALF): As a naive approach that does not require coordination of encoding, disable ALF (i.e. both fixed ALF and ALF APS) in order to merge different sub-picture representations into a single picture at the cost of losing considerable coding efficiency. - Solution 2 (disable ALF APS): Enable pre-defined fixed ALF, while disable ALF APS usage for each sub-picture, at the cost of ignoring the coding efficiency benefit brought by the adaptation of ALF parameters.

[0043] The term along the bitstream, e.g., indication along the bitstream, can be defined as: referring to out-of-band transmission, signaling, or storage of data associated with the bitstream in a manner that the data is associated with the bitstream. The term decoded along the bitstream, etc. can refer to: decoding the referred out-of-band data associated with the bitstream (which can be obtained from the out-of-band transmission, signaling, or storage). For example, the indication along the bitstream can refer to metadata in a container file that encapsulates the bitstream.

[0044] A video frame can be provided with accompanying reconstruction signals for controlling the reconstruction or visibility of parts or even individual pixels of the frame at decoding time. One example of such accompanying reconstruction signals is the occupancy picture (also referred to as occupancy map or occupancy component) used in MPEG-based volumetric video coding (V3C). The occupancy component can inform a V3C decoding and / or rendering system which samples in the 2D component are associated with data in the final 3D representation. Another example is the alpha channel (also referred to as alpha mask), which provides alpha values defining the transparency level of parts or even individual pixels of the frame. As a more detailed example, V3C video coding is described in further detail below to illustrate how occupancy is used at the decoder to reconstruct the original 3D model.

[0045] The first texture picture can be encoded into the bitstream, and the first texture picture can comprise a first projection of texture data of a first source volume of a scene model onto a first projection surface. The scene model can comprise a plurality of other source volumes.

[0046] In the projection, data about the position of the original geometric primitives can also be determined, and based on the determination, a geometry picture can be formed. This can happen, for example, such that depth data is determined for each or some of the texture pixels of the texture picture. The depth data is formed such that a distance from an original geometric primitive, such as a point, to the projection surface is determined for the pixel. Such depth data can be represented as a depth picture, and similar to the texture picture, such a geometry picture, such as a depth picture, can be encoded and decoded by a video codec. The first geometry picture can be seen as representing a mapping of the first projection surface onto the first source volume, and the decoder can use this information to determine the position of the geometric primitives in the model to be reconstructed. In order to determine the position of the first source volume and / or the first projection surface and / or the first projection in the scene model, the first geometry information can be encoded into or with the bitstream. It should be noted that the encoding of the geometry (or depth) picture into or with the bitstream is only optional or arbitrary, for example, in case the distance of all texture pixels to the projection surface is the same or there is no variation in said distance between multiple texture pictures. Thus, the encoding of the geometry (or depth) picture into or with the bitstream is only done, for example, when there is a variation in the distance of the texture pixels to the projection surface.

[0047] An attribute picture can be defined as a picture comprising additional information related to an associated texture picture. The attribute picture can for example comprise surface normal, opacity, or reflectance information for the texture picture. A geometry picture can be seen as a type of attribute picture, although a geometry picture can be separate from an attribute picture, being seen as its own picture type.

[0048] The texture picture(s) and the corresponding geometry picture(s) (if present) and the corresponding attribute picture(s) can have the same or different chroma formats.

[0049] The terms texture (component) image and texture (component) picture can be used interchangeably. The terms geometry (component) image and geometry (component) picture can be used interchangeably. One specific type of geometry image is a depth image. The described embodiments related to geometry (component) images apply equally to depth (component) images, and the described embodiments related to depth (component) images apply equally to geometry (component) images. The terms attribute image and attribute picture can be used interchangeably. In video / image encoding and / or decoding, geometry pictures and / or attribute pictures can be considered as auxiliary pictures.

[0050] Figure 3a and 3b An overview of an exemplary compression / decompression process is illustrated. The process can, for example, be applied in MPEG-based encoding of volumetric video (V3C), which is currently defined in ISO / IEC DIS 23090-5: “Coding of volumetric video and video-based point cloud compression”, 2nd edition.

[0051] The V3C specification enables encoding and decoding processes of various volumetric media by using video and image encoding techniques. This is achieved by first converting such media from their corresponding 3D representation into multiple 2D representations (also referred to as V3C components) before encoding such information. Such representations can include occupancy, geometry, and attribute components. The occupancy component is able to inform the V3C decoding and / or rendering system which samples in the 2D components are associated with data in the final 3D representation. The geometry component contains precise positions of the 3D data in space, while the attribute component can provide additional attributes of such 3D data, such as texture or material information. An example of volumetric media conversion at the encoder is illustrated in Figure 2 a, and an example of 3D reconstruction at the decoder is illustrated in Figure 3b .

[0052] The V3C decoder receives three video bitstreams as well as a V3C atlas bitstream and reconstructs the volumetric video frame-by-frame as follows: 1. The decoder reconstructs the patch locations in 3D space based on the atlas bitstream; 2. The decoder reconstructs the patch shape from the occupancy map signal; 3. The decoder reconstructs the 3D position of each point per patch based on the geometry video; 4. The decoder applies attributes to each point, e.g., texture color.

[0053] The different stages of the process are illustrated in Figure 4Visualized.

[0054] There are alternatives to capture and represent volumetric frames. The format used to capture and represent volumetric frames depends on the processing that will be performed on them, and the target application using the volumetric frames. As a first example, a volumetric frame can be represented as a point cloud. A point cloud is a collection of unstructured points in a 3D space, where each point is characterized by its position in a 3D coordinate system (e.g. a Euclidean coordinate system) and some corresponding attributes (e.g. color information provided as RGBA values, or a normal vector). As a second example, a volumetric frame can be represented as images with or without depth captured from multiple viewpoints in a 3D space. In other words, a volumetric video can be represented by one or more view frames (where a view is a projection of the volumetric scene onto a face (camera face) using a real or virtual camera with known / computed extrinsic and intrinsic). Each view can be represented by multiple components (e.g. geometry, color, transparency, and occupancy pictures), which can be part of a collection picture or represented separately. As a third example, a volumetric frame can be represented as a mesh. A mesh is a collection of points called vertices and connectivity information between vertices called edges. Vertices together with edges form faces. The combination of vertices, edges and faces can uniquely approximate the shape of an object.

[0055] Depending on the capture, a volumetric frame can provide to a viewer the ability to navigate the scene with six degrees of freedom, i.e. both the translational and rotational motion of its viewing pose (which includes yaw, pitch and roll). The data to be encoded for a volumetric frame can also be very large, as a volumetric frame can include a large number of objects, and the positioning and movement of these objects in the scene can result in a large number of unoccluded areas. Moreover, the interaction of light and materials in the objects and surfaces in a volumetric frame can generate complex light fields that can produce texture variations due to even slight changes in pose.

[0056] A sequence of volumetric frames is a volumetric video. Due to the large amount of information, the storage and transmission of a volumetric video requires compression. One way to compress a volumetric frame is to project the 3D geometry and associated attributes into a set of 2D images, together with additional associated metadata. The projected 2D images can then be encoded using 2D video and image encoding techniques, e.g. ISO / IEC 14496-10 (H.264 / AVC) and ISO / IEC 23008-2 (H.265 / HEVC). The metadata can be encoded using techniques specified in the specifications, such as ISO / IEC 23090-5. The encoded images and associated metadata can be stored or transmitted to a client that can decode and render the 3D volumetric frames.

[0057] As mentioned above, modern video codecs make use of in-loop filtering to reduce coding artifacts caused by, for example, quantized transform coefficients. In-loop filters such as Deblocking Filter (DBF), Adaptive Loop Filter (ALF), Sample Adaptive Offset (SAO) perform well on traditional 2D video content.

[0058] However, for video content that comes with a reconstructed signal, e.g. occupancy or alpha channel of a V3C video, such filtering can lead to unwanted distortions and reduced coding efficiency when applied to areas that are not intended to be reconstructed at the decoder, i.e. areas in the geometry and attribute video for which the corresponding occupancy map video area of a V3C video is set to 0, or areas for which the alpha channel is set to be fully transparent.

[0059] In the following, an enhanced method will be described in more detail according to various embodiments.

[0060] Figure 5 The method disclosed in the following comprises: obtaining (500) a video signal, the video signal comprising a block of video frames, the block comprising a plurality of pixels; obtaining (502) information indicative of a reconstruction or visibility with respect to the pixels in the block at decoding; and based on the information indicative of a reconstruction or visibility with respect to the pixels in the block, disabling (504) in-loop filtering for the aforementioned block having only a subset of pixels that will be reconstructed or visible at decoding.

[0061] Thus, based on the auxiliary input indicative information with respect to the reconstruction of the pixels in the block at decoding, e.g. an occupancy signal, the method enables to remove at least part of the distortions and increase coding efficiency by reducing the bit rate with which some or all of the video codec in-loop filters are activated and deactivated. Based on this information, the encoder can disable in-loop filtering for the aforementioned block having only a subset of pixels that will be reconstructed or visible at decoding.

[0062] It should be noted that in the present context, the term "subset of pixels" refers to a block, wherein at least one but not all pixels of the block are indicated to be reconstructed or visible at decoding.

[0063] The principle of the method can be illustrated by the example shown in Figure 6 which shows three possible states (A, B, C) of a block, such as an 8x8 pixel Coding Unit (CU). For each state, the upper block represents the video, i.e. the Coding Unit, while the lower block, i.e. the reconstruction information CU, represents the information indicative of a reconstruction with respect to the pixels in the block. White values in the reconstruction information CU indicate that the corresponding pixel is visible / reconstructed at the decoder, while dark values indicate that the respective pixel is not visible / non-reconstructed at the decoder.

[0064] The three states can be summarized as follows: A. All pixels (pixel, sample values) in the CU will be reconstructed / visible at the decoder; B. None of the pixels in the CU will be reconstructed / visible at the decoder; C. Some (subset) of the pixels in the CU will be reconstructed / visible at the decoder.

[0065] Based on these states, the encoder adaptively steers the in-loop filtering process for each state, such as: A. The visual distortion will be visible at the decoder, but the CU content represents "typical" video content, and the in-loop filters are expected to perform optimally. No changes are made to the in-loop filtering process, and the RDO calculation can remain original. B. The visual distortion will not be visible at the decoder, so no changes are needed to the in-loop filtering process. The RDO calculation can be optimized, favoring reduced rate over increased distortion. C. A subset of the pixels in the CU will be reconstructed / visible at the decoder, so the visual distortion will be visible. The boundary introduced due to the occupancy information within the CU changes the video content characteristics. As a result, the in-loop filter(s) cannot be performed with optimal performance, and thus they are disabled.

[0066] According to an embodiment, the information indicative of the reconstruction or visibility at decoding of the pixels in the block is one or more of: - an occupancy map video; - an occupancy signal; - an alpha map video; - an alpha channel.

[0067] In this context, the occupancy map video handles the V3C V-PCC use case by indicating which pixel positions will be reconstructed / visible at the decoder. The occupancy signal, which can be multiplexed in the same or another video, handles the V3C MIV use case by indicating which pixel positions will be reconstructed / visible at the decoder, where, for example, values below a certain offset are considered unoccupied. The alpha map video and the alpha channel handle the alpha use case accordingly.

[0068] According to an embodiment, the video signal comprises one or more of: - a separate video stream; - an independent layer of multi-layer encoding; - a separate sub-layer; - independent pictures arranged in a time interleaved fashion in the same coded layer video sequence; - independent constituent frames in a spatial frame compressed video.

[0069] According to an embodiment, the block is one of: a coding unit (CU), a prediction unit (PU), a transform unit (TU), a coding tree unit (CTU), a slice, or a sub-picture.

[0070] Thus, the size of the block to be processed is independent of the implementation.

[0071] According to an embodiment, the method comprises excluding from the filter parameter derivation stage samples corresponding to pixels that do not become visible at decoding.

[0072] Thus, when the visual distortion will not be visible at the decoder side (i.e. state B in the above), the corresponding samples in the encoder side will be excluded from the filter parameter derivation stage. For example, the adaptive loop filter (ALF) training in the encoder side can use only samples that will be visible at the decoder side. In another example, other filters such as luma mapping with chroma scaling (LMCS) and sample adaptive offset filter (SAO) can follow the same principle.

[0073] According to an embodiment, the method comprises including in the filter parameter derivation stage only samples corresponding to pixels in a boundary region of pixels that become visible and non-visible at decoding.

[0074] Thus, in samples whose visual distortion will not be visible at the decoder side, only those samples in the boundary region of visible and non-visible samples of the decoder can be used in the encoder side for training in-loop filters such as ALF and SAO. Figure 6 An example of such a boundary region is demonstrated in state C of the above. Including such samples can guide in-loop filters by more accurately classifying those boundary regions, and thus the resulting filtering process can be performed better.

[0075] According to an embodiment, the method comprises adjusting filter strength for said samples corresponding to pixels in said boundary region of pixels that become visible and non-visible at decoding.

[0076] When applying filtering on a block containing both visible and non-visible samples at the decoder (e.g. state C in the above), Figure 6 The filter strength can be adjusted so that it has a weaker impact on samples in the boundary region of both sample types. For example, a weaker deblocking filter can be considered in such regions. Thus, the weaker filtering can still preserve object edges in the boundary region of both sample types while reducing coding artifacts.

[0077] According to an embodiment, the method comprises computing a dedicated filter class for a block comprising pixels that both become visible and non-visible at decoding.

[0078] Thus, for the decoder, a dedicated filter class can be computed for blocks comprising both visible and non-visible samples (e.g. Figure 6 State C). For example, the ALF filter can contain one or more filter classes trained for such cases. At the decoder side, the occupancy information available can be used to indicate the filter class based on the content.

[0079] According to an embodiment, the method comprises disabling all in-loop filters for blocks comprising pixels that become both visible and non-visible at decoding.

[0080] Thus, the encoder can disable all in-loop filters for blocks (such as CUs) that partly contain reconstructed / visible content.

[0081] According to an embodiment, the method comprises using only a subset of in-loop filters for blocks comprising pixels that become both visible and non-visible at decoding.

[0082] Thus, the encoder uses a subset of in-loop filters for blocks (such as CUs) that partly contain reconstructed / visible content. For example, the encoder can only use LMCS and SAO, while disabling DBF and ALF.

[0083] According to an embodiment, the method comprises applying at least one in-loop filter only for pixels of blocks that become visible at decoding.

[0084] As an alternative, the encoder does not disable in-loop filters, however, the filters are only applied on pixels marked as visible / reconstructed at the decoder, while other pixels remain at the original values.

[0085] According to an embodiment, the method comprises a combination of applying in-loop filters block-wise and / or pixel-wise.

[0086] Thus, the encoder can apply or disable one or more in-loop filters on block level, and at the same time, apply or disable one or more in-loop filters on pixel level. For example, DBF can be disabled for each CU, while ALF is applied for each pixel.

[0087] According to an embodiment, the method comprises completely or partially deactivating one or more in-loop filters for blocks comprising only pixels that do not become visible at decoding.

[0088] Thus, for blocks containing only non-visible sample types (e.g. Figure 6 State B) at the decoder, one or more in-loop filters can be completely or partially deactivated.

[0089] According to an embodiment, the method comprises skipping signaling of filter information for said completely or partially deactivated one or more in-loop filters.

[0090] Thus, the signaling of filter information for one or more in-loop filters of a base codec can also be skipped and a predefined value can be assigned for the in-loop filter. Thus, the filter information can comprise one or more of the following: filter activation, filter type, filter class and index, etc.

[0091] According to an embodiment, the method comprises signaling one or more parameters regarding the applicability of in-loop filters in or with a bitstream of the video signal.

[0092] Thus, another aspect of the present application relates to a signaling of reconstruction guided in-loop filtering, which can be performed e.g. in or with a bitstream of a video signal. In the following, various example embodiments for carrying the signaling are given.

[0093] According to an embodiment, the method comprises implementing the signaling in a video parameter set raw byte sequence payload (RBSP) syntax or a sequence parameter set raw byte sequence payload (RBSP) syntax, wherein the signaling comprises a flag indicating the activation of reconstruction guided in-loop filtering.

[0094] An example of the signaling is shown below:

[0095] In the above example, a new syntax element vps / sps_reconstruction_guided_inloop_present_flag is introduced, wherein a flag value equal to 0 specifies that reconstruction guided in-loop filtering is not activated and a flag value equal to 1 specifies that reconstruction guided in-loop filtering is activated.

[0096] According to an alternative embodiment, the method comprises signaling one or more parameters regarding the applicability of in-loop filters as supplemental enhancement information (SEI) messages.

[0097] According to an embodiment, the signaling comprises a reference to reconstruction guided in-loop filtering as part of a multi-layer coding structure.

[0098] An example of such a signaling is shown below:

[0099] Here, the new syntax element vps_reconstruction_layer_id specifies the nuh_layer_id value of the layer carrying the reconstruction information related to the reconstruction guided in-loop filter.

[0100] According to an embodiment, the signaling comprises indicating the layers using reconstruction guided in-loop filtering per dependent layer.

[0101] An example of such signaling is shown below:

[0102] Here, the new syntax element vps_reconstruction_guided_inloop_present_flag[i] has a value equal to 1 specifies that the i-th layer uses reconstruction guided in-loop filtering. vps_reconstruction_guided_inloop_present_flag[i] equal to 0 specifies that the i-th layer does not use reconstruction guided in-loop filtering. The new syntax element vps_reconstruction_layer_idx[i] specifies the layer index to the reconstruction information for the i-th layer is ReferenceLayerIdx[i][vps_reconstruction_layer_idx[i]].

[0103] According to an embodiment, the signaling comprises separately indicating the activation of one or more in-loop filters.

[0104] An example of such signaling is shown below:

[0105] Here, new syntax elements are introduced:

[0106] vps_reconstruction_lmcs_flag equal to 0 specifies that the LMCS in-loop filter is not applied if partial reconstruction information is available. vps_reconstruction_lmcs_flag equal to 1 specifies that the LMCS in-loop filter is applied if partial reconstruction information is available.

[0107] vps_reconstruction_dbf_flag equal to 0 specifies that the DBF in-loop filter is not applied if partial reconstruction information is available. vps_reconstruction_dbf_flag equal to 1 specifies that the DBF in-loop filter is applied if partial reconstruction information is available.

[0108] vps_reconstruction_sao_flag equal to 0 specifies that the SAO in-loop filter is not applied if partial reconstruction information is available. vps_reconstruction_sao_flag equal to 1 specifies that the SAO in-loop filter is applied if partial reconstruction information is available.

[0109] vps_reconstruction_alf_flag equal to 0 specifies that no ALF in-loop filter is applied if partial reconstruction information is available. vps_reconstruction_alf_flag equal to 1 specifies that an ALF in-loop filter is applied if partial reconstruction information is available.

[0110] According to embodiments, the signaling comprises both a flag indicating the activation of in-loop filtering of the reconstruction steering and an indication for the activation of the separate one or more filters.

[0111] An example of such signaling is shown below:

[0112] Here, the flag value is indicated by two bits, enabling a more versatile signaling. The new syntax element is introduced as follows:

[0113] vps_reconstruction_lmcs_flag equal to 0 specifies that no LMCS in-loop filter is applied if partial reconstruction information is available. vps_reconstruction_lmcs_flag equal to 1 specifies that an LMCS in-loop filter is applied if partial reconstruction information is available per CU. vps_reconstruction_lmcs_flag equal to 2 specifies that an LMCS in-loop filter is applied only to samples with available reconstruction information.

[0114] vps_reconstruction_dbf_flag equal to 0 specifies that no DBF in-loop filter is applied if partial reconstruction information is available. vps_reconstruction_dbf_flag equal to 1 specifies that a DBF in-loop filter is applied if partial reconstruction information is available per CU. vps_reconstruction_lmcs_flag equal to 2 specifies that a DBF in-loop filter is applied only to samples with available reconstruction information.

[0115] vps_reconstruction_sao_flag equal to 0 specifies that no SAO in-loop filter is applied if partial reconstruction information is available. vps_reconstruction_sao_flag equal to 1 specifies that an SAO in-loop filter is applied if partial reconstruction information is available per CU. vps_reconstruction_lmcs_flag equal to 2 specifies that an SAO in-loop filter is applied only to samples with available reconstruction information.

[0116] vps_reconstruction_alf_flag equal to 0 specifies that no ALF in-loop filter is applied if partial reconstruction information is available. vps_reconstruction_alf_flag equal to 1 specifies that an ALF in-loop filter is applied if partial reconstruction information is available per CU. vps_reconstruction_lmcs_flag equal to 2 specifies that an ALF in-loop filter is applied only to samples with available reconstruction information.

[0117] In another embodiment, one or more threshold syntax elements controlling the use of reconstruction information for in-loop filtering are included in the bitstream by the encoder, or with the bitstream, such as in a VPS, and / or are decoded from the bitstream or with the bitstream, such as from a VPS, by the decoder. The threshold syntax elements may, for example, define a range of sample values in the reconstruction information indicating non-visible pixels for in-loop filtering.

[0118] The following syntax table provides an example, where numReconstructionInformationLayers is a variable indicating the number of layers containing reconstruction information for guided in-loop filtering:

[0119] Here, the syntax element vps_reconstruction_luma_threshold[i] specifies that samples with a luma sample value in the range of 0 to vps_reconstruction_luma_threshold[i] inclusive indicate non-visible samples for in-loop filtering.

[0120] Another aspect relates to the operation of a decoder (or renderer / receiver / player / client). Figure 7 The method disclosed in the introduction for explaining the operation of a decoder comprises receiving (700) a bitstream, the bitstream comprising an encoded video signal, the encoded video signal comprising blocks of video frames, the blocks comprising a plurality of pixels; receiving (702), in or with the bitstream, information indicating a reconstruction or visibility with respect to the pixels in the blocks; and decoding (704) the encoded video signal in dependence on at least the information indicating a reconstruction or visibility with respect to the pixels in the blocks by disabling in-loop filtering for blocks having only a subset of pixels to be reconstructed or visible.

[0121] Accordingly, a decoding apparatus receives a bitstream comprising the reconstruction guided in-loop filter signaling as disclosed above, and including encoded video data, and reconstruction information in or with the bitstream. The reconstruction information can be provided in the form of a bitstream comprising: an encoded occupancy (V3C use case) or alpha map video (as a separate video (V3C V-PCC use case) or as a layer in a multi-layer encoding), or multiplexed in the same or another video (V3C MIV use case) reconstruction signal. If needed, the decoder first decodes the reconstruction information, then the decoder decodes the video data, activating / disabling the in-loop filter according to the information indicating the reconstruction or visibility of the pixels in the block (i.e. reconstruction information status (full, none, partial) and the received signaling).

[0122] According to embodiments, any of the above disclosed embodiments related to encoding or decoding can be similarly applied to post-processing filters. For a neural network post-processing filter, an input tensor can be formed. In embodiments, it can be indicated by the encoder (e.g. in a neural network post-processing filter characteristic (NNPFC) SEI message) that auxiliary inputs in the post-filter desired input tensor are used for reconstruction information and / or variables controlling the reconstruction information guided filtering, such as defining one or more threshold values indicating a range of sample values in the reconstruction information for pixels that are not visible for filtering. In embodiments, it can be decoded by the decoder (e.g. from the NNPFC SEI message) that auxiliary inputs in the post-filter desired input tensor are used for reconstruction information and / or variables controlling the reconstruction information guided filtering. Accordingly, the decoder forms an input tensor with the reconstruction information and / or variables controlling the reconstruction information guided filtering.

[0123] Embodiments related to the sending / encoding aspect can be implemented in an apparatus comprising: means for obtaining a video signal comprising a block of a video frame, the block comprising a plurality of pixels; means for obtaining information indicating a reconstruction or visibility of the pixels in the block at decoding; and means for, based on the information indicating the reconstruction or visibility of the pixels in the block, disabling in-loop filtering for the block having only a subset of pixels that will be reconstructed or visible at decoding.

[0124] According to embodiments, the information indicating a reconstruction or visibility of the pixels in the block at decoding is one or more of: - an occupancy map video; - an occupancy signal; - an alpha map video; - an alpha channel.

[0125] According to an embodiment, the block is one of the following: a coding unit (CU), a prediction unit (PU), a transform unit (TU), a coding tree unit (CTU), a slice, or a sub-picture.

[0126] According to an embodiment, the apparatus comprises means for excluding, from the filter parameter derivation stage, samples corresponding to pixels that do not become reconstructed or visible at decoding.

[0127] According to an embodiment, the apparatus comprises means for including, in the filter parameter derivation stage, only samples corresponding to pixels in a boundary region of pixels that are reconstructed or become visible and non-visible at decoding.

[0128] According to an embodiment, the apparatus comprises means for adjusting filter strength for samples corresponding to pixels in the boundary region of pixels that are reconstructed or become visible and non-visible at decoding.

[0129] According to an embodiment, the apparatus comprises means for computing a dedicated filter class for blocks comprising pixels that become both visible and non-visible at decoding.

[0130] According to an embodiment, the apparatus comprises means for using only a subset of in-loop filters for blocks comprising pixels that become both visible.

[0131] According to an embodiment, the apparatus comprises means for applying a combination of in-loop filters on a block-by-block and / or pixel-by-pixel basis.

[0132] According to an embodiment, the apparatus comprises means for deactivating completely or partially one or more in-loop filters for blocks comprising only pixels that do not become visible at decoding.

[0133] According to an embodiment, the apparatus comprises means for signaling, in or with a bitstream of the video signal, one or more parameters on the applicability of in-loop filters.

[0134] According to an embodiment, the apparatus comprises means for implementing the signaling in a video parameter set raw byte sequence payload (RBSP) syntax or a sequence parameter set raw byte sequence payload (RBSP) syntax, wherein the signaling comprises a flag indicating the activation of reconstruction- guided in-loop filtering.

[0135] Embodiments related to the sending / encoding side can also be implemented in an apparatus comprising at least one processor and at least one memory, said at least one memory having computer program stored thereon, the at least one memory and the computer program configured to, with the at least one processor, cause the apparatus at least to perform: obtaining a video signal, the video signal comprising a block of video frames, said block comprising a plurality of pixels; obtaining information indicative of a reconstruction or visibility of said pixels in said block at decoding time; and based on said information indicative of a reconstruction or visibility of said pixels in said block, disabling in-loop filtering for said block having only a subset of pixels that will be reconstructed or visible at decoding time.

[0136] According to an embodiment, the information indicative of a reconstruction or visibility of said pixels in said block at decoding time is one or more of: - an occupancy map video; - an occupancy signal; - an alpha map video; - an alpha channel.

[0137] According to an embodiment, the block is one of: a coding unit (CU), a prediction unit (PU), a transform unit (TU), a coding tree unit (CTU), a slice, or a sub-picture.

[0138] According to an embodiment, the apparatus comprises code configured to cause the apparatus to exclude from the filter parameter derivation stage samples corresponding to pixels that do not become reconstructed or visible at decoding time.

[0139] According to an embodiment, the apparatus comprises code configured to cause the apparatus to include in the filter parameter derivation stage only samples corresponding to pixels that are reconstructed or become visible and non-visible at the boundary region of pixels.

[0140] According to an embodiment, the apparatus comprises code configured to cause the apparatus to adjust filter strength for said samples corresponding to pixels that are reconstructed or become visible and non-visible at the boundary region of pixels.

[0141] According to an embodiment, the apparatus comprises code configured to cause the apparatus to compute a dedicated filter class for blocks comprising pixels that become both visible and non-visible at decoding time.

[0142] According to an embodiment, the apparatus comprises code configured to cause the apparatus to use only a subset of in-loop filters for blocks comprising pixels that become both visible.

[0143] According to an embodiment, the apparatus comprises code configured to cause the apparatus to apply a combination of in-loop filters block-wise and / or pixel-wise.

[0144] According to an embodiment, the apparatus comprises code configured to cause the apparatus to completely or partially deactivate one or more in-loop filters for blocks comprising only pixels that are not becoming visible at decoding time.

[0145] According to an embodiment, the apparatus comprises code configured to cause the apparatus to signal one or more parameters regarding the applicability of in-loop filters in or with a bitstream of the video signal.

[0146] According to an embodiment, the apparatus comprises code configured to cause the apparatus to implement said signaling in a video parameter set raw byte sequence payload (RBSP) syntax or a sequence parameter set raw byte sequence payload (RBSP) syntax, wherein said signaling comprises a flag indicating activation of a guided in-loop filtering.

[0147] The receiving / decoding / rendering aspect can be implemented by an apparatus comprising means for receiving a bitstream, the bitstream comprising an encoded video signal, the encoded video signal comprising blocks of video frames, said blocks comprising a plurality of pixels; means for receiving, in or with the bitstream, information indicative of a reconstruction or visibility regarding said pixels in said blocks; and means for decoding the encoded video signal in dependence on at least said information indicative of a reconstruction or visibility regarding said pixels in said blocks by disabling in-loop filtering for said blocks having only a subset of pixels to be reconstructed or visible.

[0148] Embodiments related to the receiving / decoding / rendering aspect can likewise be implemented in an apparatus comprising at least one processor and at least one memory, said at least one memory having stored thereon a computer program, the at least one memory and the computer program configured to, with the at least one processor, cause the apparatus at least to perform: receiving a bitstream, the bitstream comprising an encoded video signal, the encoded video signal comprising blocks of video frames, said blocks comprising a plurality of pixels; receiving, in or with the bitstream, information indicative of a reconstruction or visibility regarding said pixels in said blocks; and decoding the encoded video signal in dependence on at least said information indicative of a reconstruction or visibility regarding said pixels in said blocks by disabling in-loop filtering for said blocks having only a subset of pixels to be reconstructed or visible.

[0149] Such an apparatus can comprise means for implementing the functions disclosed in any of Figure 1a , 1b , 2, 3a and 3b.

[0150] In the foregoing, some embodiments have been described with reference to encoding. It is to be understood that the encoding can comprise one or more of encoding source image data into a bitstream, encapsulating the encoded bitstream in a container file and / or in a packet(s) or stream(s) of a communication protocol, and announcing or describing the bitstream in a content description such as an ISO / IEC 23009-1 media presentation description (MPD) (known as MPEG-DASH) or an IETF session description protocol (SDP). Similarly, some embodiments have been described with reference to decoding. It is to be understood that the decoding can comprise one or more of decoding image data from a bitstream, decapsulating the bitstream from a container file and / or from a packet(s) or stream(s) of a communication protocol, and parsing a content description of the bitstream.

[0151] In the foregoing, example embodiments have been described with reference to an encoder or encoding method, it is to be understood that the resulting bitstream and a decoder or decoding method can have corresponding elements. Likewise, example embodiments have been described with reference to a decoder, it is to be understood that an encoder can have structures and / or computer programs for generating a bitstream to be decoded by the decoder.

[0152] In general, the various embodiments of the application can be implemented in hardware or special-purpose circuits or combinations thereof. Although various aspects of the application can be illustrated and described as block diagrams or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein can be implemented in hardware, software, firmware, special purpose circuits or logic, general purpose hardware or control units or other computing devices, or some combination thereof.

[0153] The embodiments of the application can be practiced in a variety of components such as integrated circuit modules. The design of integrated circuits is by nature a highly automated process. Complex and powerful software programs are available for design, simulation, test, and manufacture of the circuits. Various software applications are available for design and simulation of the circuits. For example, such software applications include software protocols for simulation and modeling, cadence, and / or the like.

[0154] Programs, such as those provided by Synopsys, Inc. of Mountain View, California and Cadence Design, of San Jose, California automatically route conductors and locate components on a semiconductor chip using well-established rules of design when given the specification for the components to be used. Once the design for a semiconductor circuit has been completed, the resultant design, in a standardized electronic format (e.g., Opus, GDSII, or the like) can be transmitted to a semiconductor fabrication facility or "fab" to be fabricated (i.e., manufactured) as one or more integrated circuits or other electronic components.

[0155] The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the exemplary embodiments of the application. However, various modifications and adaptations can become apparent to those skilled in the relevant arts in view of the foregoing description, when read, not only in the light of the detailed description of the embodiments herein, but also in the light of the detailed description of the examples provided herein and the appended drawings. However, all such and similar modifications of the teachings of this application will still fall within the scope of the application.

Claims

1. An apparatus comprising: A component for acquiring video signals, the video signals comprising blocks of video frames, the blocks comprising multiple pixels; Components for acquiring information indicating the reconstruction or visibility of the pixels in the block during decoding; as well as A component for disabling in-loop filtering for the aforementioned block that has only a subset of the pixels that will be reconstructed or visible during decoding, based on the information indicating the reconstruction or visibility of the pixels in the block.

2. The apparatus of claim 1, wherein the information indicating the reconstruction or visibility of the pixels in the block during decoding is one or more of the following: - Occupied image video; - Occupying the signal; - Alpha Graph Video; - Alpha Channel.

3. The apparatus according to claim 1 or 2, wherein the block is one of the following: a coding unit (CU), a prediction unit (PU), a transform unit (TU), a coding tree unit (CTU), a strip, or a sub-picture.

4. The apparatus according to any one of the preceding claims, comprising: A component for excluding samples from the filter parameter derivation stage, the samples corresponding to pixels that do not become reconstructed or visible during decoding.

5. The apparatus according to any one of claims 1 to 3, comprising: The component is used to include only samples in the filter parameter derivation stage, the samples corresponding to pixels in the boundary regions of pixels that are reconstructed or become visible and invisible during decoding.

6. The apparatus according to claim 5, comprising: A component for adjusting the filter intensity for the sample, the sample corresponding to a pixel in the boundary region of the pixel that is reconstructed or becomes visible and invisible during decoding.

7. The apparatus according to any one of the preceding claims, comprising: A component for calculating a special filter class for blocks of pixels that become both visible and invisible during decoding.

8. The apparatus according to any one of the preceding claims, comprising: A component for using only a subset of in-loop filters for blocks of pixels that include both of which become visible.

9. The apparatus according to any one of the preceding claims, comprising: A component used for combinations of in-loop filters for block-by-block and / or pixel-by-pixel applications.

10. The apparatus according to any one of the preceding claims, comprising: A component for completely or partially deactivating one or more in-loop filters for blocks that only include pixels that do not become visible during decoding.

11. The apparatus according to any one of the preceding claims, comprising: A component for signaling, in or together with the bitstream including the video signal, one or more parameters relating to the suitability of the in-loop filter.

12. The apparatus of claim 11, comprising: A component for implementing the signaling in either Video Parameter Set Raw Byte Sequence Payload (RBSP) syntax or Sequence Parameter Set Raw Byte Sequence Payload (RBSP) syntax, wherein the signaling includes a flag indicating activation of reconstruction-guided in-loop filtering.

13. A method comprising: Acquire a video signal, the video signal comprising blocks of video frames, the blocks comprising multiple pixels; Obtain information indicating the reconstruction or visibility of the pixels in the block during decoding; as well as Based on the information indicating the reconstruction or visibility of the pixels in the block, in-loop filtering is disabled for the aforementioned block that has only a subset of the pixels that will be reconstructed or visible during decoding.

14. An apparatus comprising: A component for receiving a bitstream, the bitstream including an encoded video signal, the encoded video signal including blocks of video frames, the blocks including multiple pixels; A component for receiving, in or together with, information indicating the reconstruction or visibility of the pixels in the block; as well as A component for decoding the encoded video signal based on information indicating at least the reconstruction or visibility of the pixels in the block by disabling in-loop filtering for only a subset of the aforementioned blocks that will be reconstructed or visible.

15. A method comprising: Receive a bitstream, the bitstream including an encoded video signal, the encoded video signal including blocks of video frames, the blocks including multiple pixels; In or together with the bitstream, information indicating the reconstruction or visibility of the pixels in the block is received; as well as The encoded video signal is decoded based on information indicating at least the reconstruction or visibility of the pixels in the block by disabling in-loop filtering for only a subset of the aforementioned blocks that have pixels that will be reconstructed or visible.

Images