Adaptive clipping with signaled lower and upper limits in video coding

Abstract

A video decoder is configured to: determine a minimum sample value for one or more blocks of video data, the minimum sample value being greater than 0; determining a maximum sample value for the one or more blocks of video data, the maximum sample value being less than 2bd-1, and bd being a bit depth of a sample in the one or more blocks; in response to determining that a process applied to a block of the one or more blocks of the video data results in a sample value outside a range from the minimum sample value to the maximum sample value, clipping the sample value to one of the minimum sample value or the maximum sample value to produce a clipped sample value; a decoded version of the block is determined based on the clipped sample values.

Description

[0001] This application claims priority to U.S. Patent Application No. 18 / 883,723, filed September 12, 2024; U.S. Provisional Patent Application No. 63 / 588,246, filed October 5, 2023; and U.S. Provisional Patent Application No. 63 / 604,535, filed November 30, 2023, the entire contents of each of which are incorporated herein by reference. U.S. Patent Application No. 18 / 883,723, filed September 12, 2024, claims the benefit of U.S. Provisional Patent Application No. 63 / 588,246, filed October 5, 2023, and U.S. Provisional Patent Application No. 63 / 604,535, filed November 30, 2023. Technical Field

[0002] This disclosure relates to video encoding and video decoding. Background Technology

[0003] Digital video capabilities can be incorporated into a wide variety of devices, including digital televisions, digital live broadcast systems, wireless broadcasting systems, personal digital assistants (PDAs), laptops or desktop computers, tablets, e-book readers, digital cameras, digital recording devices, digital media players, video game devices, video game consoles, cellular or satellite wireless phones (so-called "smartphones"), video conferencing equipment, video streaming devices, and more. Digital video devices implement video decoding technologies, such as those defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264 / MPEG-4 (Part 10, Advanced Video Decoding (AVC)), ITU-T H.265 / High Efficiency Video Decoding (HEVC), ITU-T H.266 / Variety Video Decoding (VVC) and extensions to these standards, as well as proprietary video codecs / formats such as AOMedia Video1 (AV1) developed by the Open Media Alliance. By implementing such video decoding technologies, video devices can more efficiently send, receive, encode, decode, and / or store digital video information.

[0004] Video decoding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences. For block-based video decoding, video slices (e.g., video pictures or portions of video pictures) can be divided into video blocks, which may also be referred to as decoding tree units (CTUs), decoding units (CUs), and / or decoding nodes. Video blocks in a slice after intra-frame decoding (I) of a picture are encoded using spatial prediction relative to reference samples in adjacent blocks within the same picture. Video blocks in a slice after inter-frame decoding (P or B) of a picture can use spatial prediction relative to reference samples in adjacent blocks within the same picture or temporal prediction relative to reference samples in other reference pictures. A picture may be referred to as a frame, and a reference picture may be referred to as a reference frame. Summary of the Invention

[0005] Sample values ​​in video data (e.g., luma and chroma sample values) have a dynamic range from a minimum of 0 to a maximum of 2^bd - 1, where bd represents the bit depth of the video data. For example, luma and chroma samples in an 8-bit video have values ​​between 0 and 255. Various steps in the video decoding process can sometimes cause sample values ​​to fall outside this range, i.e., less than 0 or greater than 2^bd - 1. For example, adding residual samples to prediction samples may result in reconstructed samples that are outside this range. As another example, in some cases, the ALF process can modify sample values ​​that are within the range to be outside the range.

[0006] Existing video decoders are configured to crop out-of-range samples by setting sample values ​​below 0 to equal 0 and sample values ​​above that maximum value to equal that maximum value. The original (i.e., unencoded) video data of some portions of the video data (such as blocks, slices, pictures, or groups of other portions) may not have any sample values ​​equal to 0 or 2^bd -1. Instead, the minimum sample value of that portion of the video data may be greater than 0, and the maximum value may be less than 2^bd -1. This disclosure describes a technique for: configuring a video decoder to determine a minimum sample value greater than 0 and a maximum sample value less than 2^bd -1 for some portions of the video data; and subsequently, in response to the process of determining a block of video data resulting in a sample value outside the range of the minimum to the maximum sample value, cropping that sample value to either the minimum or the maximum sample value. By cropping the sample value to either the determined minimum or the determined maximum sample value instead of 0 or 2^bd -1, the decoded video data can more accurately match the original video data, thus reducing distortion introduced by the encoding process.

[0007] According to an example of this disclosure, a method for decoding video data includes: determining a minimum sample value for one or more blocks of the video data, wherein the minimum sample value is greater than 0; in response to a process of determining a block applied to the one or more blocks of the video data resulting in a sample value less than zero, cropping the sample value to the minimum sample value to produce a cropped sample value; determining a decoded version of the block based on the cropped sample value; and outputting an image of the decoded video data including the decoded version of the block.

[0008] According to an example of this disclosure, a method for decoding video data includes: determining a maximum sample value for one or more blocks of video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in one or more blocks of video data; in response to a process of determining a sample value greater than the maximum sample value resulting from a process of applying the block to one or more blocks of video data, cropping the sample value to the maximum sample value to produce a cropped sample value; determining a decoded version of the block based on the cropped sample value; and outputting an image of decoded video data including the decoded version of the block.

[0009] According to an example of this disclosure, a method for decoding video data includes: determining a minimum sample value for one or more blocks of video data, wherein the minimum sample value is greater than 0; determining a maximum sample value for the one or more blocks of video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; in response to a sample value outside the range of the minimum sample value to the maximum sample value resulting from the process of determining a block in the one or more blocks of video data, cropping the sample value to either the minimum sample value or the maximum sample value to produce a cropped sample value; determining a decoded version of the block based on the cropped sample value; and outputting an image of the decoded video data including the decoded version of the block.

[0010] According to an example of this disclosure, an apparatus for decoding video data includes: a memory configured to store video data; and one or more processors implemented in a circuit and configured to: determine a minimum sample value for one or more blocks of video data, wherein the minimum sample value is greater than 0; determine a maximum sample value for one or more blocks of video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; in response to a process of determining a block applied to the one or more blocks of video data resulting in a sample value outside the range of the minimum sample value to the maximum sample value, crop the sample value to either the minimum sample value or the maximum sample value to produce a cropped sample value; determine a decoded version of the block based on the cropped sample value; and output an image of the decoded video data including the decoded version of the block.

[0011] According to an example of this disclosure, a method for encoding video data includes: determining a minimum sample value for one or more blocks of unencoded video data, wherein the minimum sample value is greater than 0; determining a maximum sample value for the one or more blocks of the unencoded video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; encoding the unencoded video data to determine encoded video data; during decoding of the encoded video data, determining a sample value outside the range of the minimum to the maximum sample value resulting from the process of determining the sample value outside the range of the minimum to the maximum sample value resulting from the process of determining the block, cropping the sample value to either the minimum or the maximum sample value to produce a cropped sample value; determining a decoded version of the block based on the cropped sample value; and storing an image of the decoded video data including the decoded version of the block in a decoded image buffer.

[0012] According to an example of this disclosure, an apparatus for encoding video data includes: a memory configured to store video data; and one or more processors implemented in a circuit and configured to: determine a minimum sample value for one or more blocks of unencoded video data, wherein the minimum sample value is greater than 0; determine a maximum sample value for the one or more blocks of unencoded video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; encode the unencoded video data to determine encoded video data; when decoding the encoded video data, determining a block of video data resulting in a sample value outside the range of the minimum to the maximum sample value; in response to the determination of the sample value outside the range of the minimum to the maximum sample value resulting in the block, cropping the sample value to either the minimum or the maximum sample value to produce a cropped sample value; determining a decoded version of the block based on the cropped sample value; and storing an image of the decoded video data including the decoded version of the block in a decoded image buffer.

[0013] Details of one or more examples are set forth in the accompanying drawings and the following description. Other features, objects, and advantages will be apparent from the description, drawings, and claims. Attached Figure Description

[0014] Figure 1 This is a block diagram illustrating an example video encoding and decoding system that can perform the techniques of this disclosure.

[0015] Figure 2 An example of a decoding architecture that combines luminance mapping and chroma scaling is shown.

[0016] Figure 3 This is a block diagram illustrating an example video encoder that can perform the techniques of this disclosure.

[0017] Figure 4 This is a block diagram illustrating an example video decoder that can perform the techniques of this disclosure.

[0018] Figure 5 This is a flowchart illustrating an example process for encoding the current block according to the technology of this disclosure.

[0019] Figure 6 This is a flowchart illustrating an example process for decoding the current block according to the technology of this disclosure.

[0020] Figure 7 This is a flowchart illustrating an example process for decoding the current block according to the technology of this disclosure. Detailed Implementation

[0021] Video decoding (e.g., video encoding and / or video decoding) typically involves predicting video data blocks based on decoded video data blocks within the same frame (e.g., intra-frame prediction) or based on decoded video data blocks in different frames (e.g., inter-frame prediction). In some cases, the video encoder also computes residual data by comparing the predicted block to the original block. Therefore, the residual data represents the difference between the predicted block and the original block. To reduce the number of bits required to signal the residual data, the video encoder transforms and quantizes the residual data and signals the transformed and quantized residual data in the encoded bitstream. Compression achieved through the transformation and quantization process can be lossy, meaning that the transformation and quantization process may introduce distortion into the decoded video data.

[0022] The video decoder decodes the residual data and adds it to the predicted blocks to produce a reconstructed video block that more closely matches the original video block compared to individual predicted blocks. Due to losses introduced by the transformation and quantization of the residual data, the first reconstructed block may have distortion or artifacts. A common type of artifact or distortion is called block artifacts, where the boundaries of the blocks used to decode the video data are visible.

[0023] To further improve the quality of the decoded video, the video decoder can perform one or more filtering operations on the reconstructed video blocks. Examples of these filtering operations include deblocking filtering, Sample Adaptive Offset (SAO) filtering, and Adaptive Loop Filtering (ALF). The parameters of these filtering operations can be determined by the video encoder and explicitly signaled in the encoded video bitstream, or they can be implicitly determined by the video decoder without needing to be explicitly signaled in the encoded video bitstream.

[0024] Sample values ​​in video data (e.g., luma and chroma sample values) have a dynamic range from a minimum of 0 to a maximum of 2^bd - 1, where bd represents the bit depth of the video data. For example, luma and chroma samples in an 8-bit video have values ​​between 0 and 255. Various steps in the video decoding process can sometimes cause sample values ​​to fall outside this range, i.e., less than 0 or greater than 2^bd - 1. For example, adding residual samples to prediction samples may result in reconstructed samples that are outside this range. As another example, in some cases, the ALF process can modify sample values ​​that are within the range to fall outside the range.

[0025] Existing video decoders are configured to crop out-of-range samples by setting sample values ​​below 0 to equal 0 and sample values ​​above that maximum value to equal that maximum value. The original (i.e., unencoded) video data of some portions of the video data (such as blocks, slices, pictures, or groups of other portions) may not have any sample values ​​equal to 0 or 2^bd -1. Instead, the minimum sample value of that portion of the video data may be greater than 0, and the maximum value may be less than 2^bd -1. This disclosure describes a technique for: configuring a video decoder to determine a minimum sample value greater than 0 and a maximum sample value less than 2^bd -1 for some portions of the video data; and subsequently, in response to the process of determining a block of video data resulting in a sample value outside the range of the minimum to the maximum sample value, cropping that sample value to either the minimum or the maximum sample value. By cropping the sample value to either the determined minimum or the determined maximum sample value instead of 0 or 2^bd -1, the decoded video data can more accurately match the original video data, thus reducing distortion introduced by the encoding process.

[0026] As used in this disclosure, the term video decoding generally refers to video encoding or video decoding. Similarly, the term "video decoder" generally refers to a video encoder or a video decoder. Furthermore, some of the techniques described in this disclosure with respect to video decoding can also be applied to video encoding, and vice versa. For example, video encoders and video decoders are often configured to perform the same or opposite processes. Moreover, video encoders typically perform video decoding (also known as reconstruction) as part of a process of determining how to encode video data. For example, a video encoder may perform the same cropping process on a decoded video block as a video decoder to determine whether a particular encoding scheme produces the desired bit rate distortion trade-off and also to allow the video encoder to perform motion evaluation using the same blocks available to the video decoder when the video decoder performs motion compensation.

[0027] This disclosure relates to data trimming and dynamic range trimming in video decoding. The techniques disclosed herein can be applied to any of existing video codecs (such as HEVC (High Efficiency Video Decoding), VVC (Various Video Decoding), and EVC (Essential Video Decoding), or can be efficient decoding tools in future video decoding standards.

[0028] Figure 1 This is a block diagram illustrating an example video encoding and decoding system 100 capable of performing the techniques of this disclosure. The techniques of this disclosure generally involve decoding (encoding and / or decoding) video data. Typically, video data includes any data used for processing video. Therefore, video data may include unencoded raw video, encoded video, decoded (e.g., reconstructed) video, and video metadata, such as signaling data.

[0029] like Figure 1 As shown, in this example, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a destination device 116. Specifically, source device 102 provides video data to destination device 116 via computer-readable medium 110. Source device 102 and destination device 116 can be or may include any of a wide range of devices, such as desktop computers, laptop computers, mobile devices, tablet computers, set-top boxes, mobile phones (such as smartphones), televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, broadcast receiver devices, etc. In some cases, source device 102 and destination device 116 may be configured for wireless communication and are therefore referred to as wireless communication devices.

[0030] exist Figure 1 In the example, source device 102 includes a video source 104, memory 106, video encoder 200, and output interface 108. Destination device 116 includes an input interface 122, video decoder 300, memory 120, and display device 118. According to this disclosure, the video encoder 200 of source device 102 and the video decoder 300 of destination device 116 can be configured to apply techniques for adaptive cropping. Thus, source device 102 represents an example of a video encoding device, while destination device 116 represents an example of a video decoding device. In other examples, the source device and destination device may include other components or arrangements. For example, source device 102 may receive video data from an external video source such as an external camera. Similarly, destination device 116 may interface with an external display device, rather than including an integrated display device.

[0031] like Figure 1The system 100 shown is merely an example. Typically, any digital video encoding and / or decoding device can perform the adaptive cropping techniques described herein. Source device 102 and destination device 116 are merely examples of such decoding devices, where source device 102 generates decoded video data for transmission to destination device 116. This disclosure refers to a “decoding” device as a device that performs the decoding (e.g., encoding and / or decoding) of data. Thus, video encoder 200 and video decoder 300 represent examples of decoding devices, specifically, a video encoder and a video decoder, respectively. In some examples, source device 102 and destination device 116 may operate in a substantially symmetrical manner, such that each of source device 102 and destination device 116 includes video encoding and decoding components. Therefore, system 100 may support one-way or two-way video transmission between source device 102 and destination device 116, for example, for video streaming, video playback, video broadcasting, or video telephony.

[0032] Generally, video source 104 represents the source of video data (i.e., raw, unencoded video data) and provides a sequential series of pictures (also referred to as "frames") of the video data to video encoder 200, which encodes the data for the pictures. Video source 104 of source device 102 may include video capture devices such as cameras, video archives containing previously captured raw video, and / or video feed interfaces for receiving video from video content providers. Alternatively, video source 104 may generate computer graphics-based data as source video, or a combination of live video, archived video, and computer-generated video. In each case, video encoder 200 encodes the captured, pre-captured, or computer-generated video data. Video encoder 200 may rearrange the pictures from the received order (sometimes referred to as "display order") to a decoding order for decoding. Video encoder 200 may generate a bitstream comprising the encoded video data. Then, the source device 102 can output the encoded video data to the computer-readable medium 110 via the output interface 108 for reception and / or retrieval by, for example, the input interface 122 of the destination device 116.

[0033] The memory 106 of source device 102 and the memory 120 of destination device 116 represent general-purpose memory. In some examples, memories 106 and 120 may store raw video data, such as raw video from video source 104 and raw decoded video data from video decoder 300. Additionally or alternatively, memories 106 and 120 may store software instructions executable by, for example, video encoder 200 and video decoder 300. Although memories 106 and 120 are shown separately from video encoder 200 and video decoder 300 in this example, it should be understood that video encoder 200 and video decoder 300 may also include internal memory for functionally similar or equivalent purposes. Furthermore, memories 106 and 120 may store encoded video data, such as output from video encoder 200 and input to video decoder 300. In some examples, portions of memories 106 and 120 may be allocated as one or more video buffers, for example, to store raw decoded and / or encoded video data.

[0034] Computer-readable medium 110 may represent any type of medium or device capable of transmitting encoded video data from source device 102 to destination device 116. In one example, computer-readable medium 110 represents a communication medium that enables source device 102 to directly transmit encoded video data to destination device 116 in real time, for example, via a radio frequency network or a computer-based network. According to a communication standard such as a wireless communication protocol, output interface 108 may modulate the transmitted signal including the encoded video data, and input interface 122 may demodulate the received transmitted signal. The communication medium may include any wireless or wired communication medium, such as radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet-based network such as a local area network, a wide area network, or a global network (such as the Internet). The communication medium may include a router, switch, base station, or any other equipment that may be useful for facilitating communication from source device 102 to destination device 116.

[0035] In some examples, source device 102 can output encoded data from output interface 108 to storage device 112. Similarly, destination device 116 can access encoded data from storage device 112 via input interface 122. Storage device 112 may include any data storage medium of various distributed or locally accessed data storage media, such as hard disk drives, Blu-ray discs, DVDs, CD-ROMs, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0036] In some examples, source device 102 can output encoded video data to file server 114 or another intermediate storage device that can store the encoded video data generated by source device 102. Destination device 116 can access the stored video data from file server 114 via streaming or download.

[0037] File server 114 can be any type of server device capable of storing encoded video data and sending the encoded video data to destination device 116. File server 114 may represent a web server (e.g., for a website), a server configured to provide file transfer protocol services (such as File Transfer Protocol (FTP) or FLUTE-based file delivery protocol), a Content Delivery Network (CDN) device, a Hypertext Transfer Protocol (HTTP) server, a Multimedia Broadcast Multicast Service (MBMS) or Enhanced MBMS (eMBMS) server, and / or a Network Attached Storage (NAS) device. File server 114 may additionally or alternatively implement one or more HTTP streaming protocols, such as HTTP-based Dynamic Adaptive Streaming (DASH), HTTP Live Streaming (HLS), Real-Time Streaming Protocol (RTSP), HTTP Dynamic Streaming, etc.

[0038] Destination device 116 can access encoded video data from file server 114 via any standard data connection, including an internet connection. This may include a wireless channel (e.g., Wi-Fi connection), a wired connection (e.g., digital subscriber line (DSL), cable modem, etc.), or a combination of both, suitable for accessing encoded video data stored on file server 114. Input interface 122 can be configured to operate according to any or more of the various protocols discussed above for retrieving or receiving media data from file server 114, or other such protocols for retrieving media data.

[0039] Output interface 108 and input interface 122 can represent a wireless transmitter / receiver, a modem, a wired networking component (e.g., an Ethernet card), a wireless communication component operating according to any of the various IEEE 802.11 standards, or other physical components. In examples where output interface 108 and input interface 122 include wireless components, output interface 108 and input interface 122 can be configured to transmit data such as encoded video data according to cellular communication standards such as 4G, 4G-LTE (Long Term Evolution), Advanced LTE, 5G, etc. In some examples where output interface 108 includes a wireless transmitter, output interface 108 and input interface 122 can be configured according to other wireless standards such as the IEEE 802.11 specification, the IEEE 802.15 specification (e.g., ZigBee), etc.™ ),Bluetooth ™ Standards are used to transmit data such as encoded video data. In some examples, source device 102 and / or destination device 116 may include corresponding system-on-chip (SoC) devices. For example, source device 102 may include an SoC device for performing functions belonging to video encoder 200 and / or output interface 108, and destination device 116 may include an SoC device for performing functions belonging to video decoder 300 and / or input interface 122.

[0040] The technology disclosed herein can be applied to video decoding to support any multimedia application in a variety of multimedia applications, such as over-the-air television broadcasting, cable television transmission, satellite television transmission, internet streaming video transmission (such as HTTP-based Dynamic Adaptive Streaming (DASH)), digital video encoded onto data storage media, decoding of digital video stored on data storage media, or other applications.

[0041] The input interface 122 of the destination device 116 receives an encoded video bitstream from a computer-readable medium 110 (e.g., a communication medium, storage device 112, file server 114, etc.). The encoded video bitstream may include signaling information defined by the video encoder 200 and also used by the video decoder 300, such as syntax elements having values ​​describing the characteristics and / or processing of video blocks or other decoded units (e.g., slices, pictures, picture groups, sequences, etc.). The display device 118 displays a decoded picture of the decoded video data to the user. The display device 118 may represent any of a variety of display devices, such as a liquid crystal display (LCD), a plasma display, an organic light-emitting diode (OLED) display, or another type of display device.

[0042] Despite Figure 1Not shown, but in some examples, both the video encoder 200 and the video decoder 300 may be integrated with the audio encoder and / or audio decoder (e.g., audio codec), and may include appropriate MUX-DEMUX units or other hardware and / or software to process multiplexed streams that include both audio and video in a common data stream. Example audio codecs may include AAC, AC-3, AC-4, ALAC, ALS, AMBE, AMR, AMR-WB (G.722.2), AMR-WB+, aptX (various versions), ATRAC, BroadVoice (BV16, BV32), CELT, Enhanced AC-3 (E-AC-3), EVS, FLAC, G.711, G.722, G.722.1, G.722.2 (AMR-WB), G.723.1, G.726, G.728, G.729, G.729.1, GSM-FR, HE-AAC, iLBC, iSAC, LA Lyra, Monkey's Audio, MP1, MP2 (MPEG-1, 2 Audio Layer II), MP3, Musepack, Nellymoser Asao, OptimFROG, Opus, Sac, Satin, SBC, SILK, Siren 7, Speex, SVOPC, True Audio (TTA), TwinVQ, USAC, Vorbis (Ogg), WavPack and Windows Media Aud.

[0043] Both the video encoder 200 and the video decoder 300 can be implemented as any of a variety of suitable encoder and / or decoder circuits comprising a processing system, such as one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware, or any combination thereof. When the technology is implemented in part in software, the device may store instructions for the software in a suitable non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the technology of this disclosure. Each of the video encoder 200 and the video decoder 300 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined encoder / decoder (CODEC) in the respective device. Devices including the video encoder 200 and / or the video decoder 300 may implement the video encoder 200 and / or the video decoder 300 in processing circuitry such as integrated circuits and / or microprocessors. Such devices may be wireless communication devices (such as cellular phones) or any other type of device described herein.

[0044] The video encoder 200 and video decoder 300 may operate according to a video decoding standard such as ITU-T H.265 (also known as High Efficiency Video Decoding (HEVC)) or extensions thereof such as MultiView and / or Scalable Video Decoding Extensions. Alternatively, the video encoder 200 and video decoder 300 may operate according to other proprietary or industry standards such as ITU-T H.266 (also known as Multi-Functional Video Decoding (VVC)). In other examples, the video encoder 200 and video decoder 300 may operate according to proprietary video codecs / formats such as AOMedia Video 1 (AV1), extensions to AV1, and / or subsequent versions of AV1 (e.g., AV2)). In other examples, the video encoder 200 and video decoder 300 may operate according to other proprietary formats or industry standards. However, the techniques disclosed herein are not limited to any particular decoding standard or format. Generally, the video encoder 200 and video decoder 300 may be configured to perform the techniques of this disclosure in conjunction with any video decoding technique that uses clipping of sample values.

[0045] Typically, video encoder 200 and video decoder 300 perform block-based decoding of images. The term "block" generally refers to a structure that includes data to be processed (e.g., encoded, decoded, or otherwise used during encoding and / or decoding). For example, a block may include a two-dimensional matrix of samples of luminance and / or chrominance data. Typically, video encoder 200 and video decoder 300 decode video data represented in YUV (e.g., Y, Cb, Cr) format. That is, instead of decoding the red, green, and blue (RGB) data used for images, video encoder 200 and video decoder 300 decode the luminance and chrominance components, where the chrominance components may include both red hue chrominance components and blue hue chrominance components. In some examples, video encoder 200 converts the received RGB format data to a YUV representation before encoding, and video decoder 300 converts the YUV representation to RGB format. Alternatively, preprocessing and postprocessing units (not shown) may perform these conversions.

[0046] This disclosure generally relates to the decoding (e.g., encoding and decoding) of images to include processes of encoding or decoding data of the image. Similarly, this disclosure may relate to the decoding of blocks of images to include processes of encoding or decoding data used for the blocks (e.g., prediction and / or residual decoding). Encoded video bitstreams typically include a series of values ​​for syntax elements representing decoding decisions (e.g., decoding modes) and the partitioning of images into blocks. Therefore, references to the decoding of images or blocks should generally be understood as the decoded values ​​of the syntax elements that form the images or blocks.

[0047] HEVC defines various blocks, including decoding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video decoder (such as a video encoder 200) divides the decoding tree unit (CTU) into CUs based on a quadtree structure. That is, the video decoder divides the CTU and CU into four equal, non-overlapping squares, and each node of the quadtree has zero or four child nodes. Nodes without child nodes are called "leaf nodes," and the CU of such leaf nodes may include one or more PUs and / or one or more TUs. The video decoder may further divide the PUs and TUs. For example, in HEVC, a residual quadtree (RQT) represents the partitioning of the TU. In HEVC, the PU represents inter-frame prediction data, while the TU represents residual data. The CU after intra-frame prediction includes intra-frame prediction information, such as intra-frame mode indication.

[0048] As another example, video encoder 200 and video decoder 300 can be configured to operate according to VVC. According to VVC, the video decoder (such as video encoder 200) partitions the image into multiple CTUs. Video encoder 200 can partition the CTUs according to a tree structure (such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure). The QTBT structure removes the concept of multiple partition types, such as the separation between CUs, PUs, and TUs in HEVC. The QTBT structure includes two levels: a first level partitioned according to a quadtree and a second level partitioned according to a binary tree. The root node of the QTBT structure corresponds to a CTU. The leaf nodes of the binary tree correspond to CUs.

[0049] In the MTT partitioning structure, blocks can be divided using quadtree (QT) partitioning, binary tree (BT) partitioning, and one or more types of ternary tree (TT) partitioning (also known as triplet tree (TT)). A ternary tree or triplet tree partition is a partition in which a block is divided into three sub-blocks. In some examples, a ternary tree or triplet tree partition divides a block into three sub-blocks without dividing the original block through the center. Partition types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0050] When operating according to the AV1 codec, the video encoder 200 and video decoder 300 can be configured to decode video data in blocks. In AV1, the largest decoded block that can be processed is called a superblock. In AV1, a superblock can be 128x128 luma samples or 64x64 luma samples. However, in subsequent video decoding formats (e.g., AV2), superblocks can be defined by different (e.g., larger) luma sample sizes. In some examples, the superblock is the top level of a block quadtree. The video encoder 200 can further divide the superblock into smaller decoded blocks. The video encoder 200 can use square or non-square partitions to divide the superblock and other decoded blocks into smaller blocks. Non-square blocks can include N / 2xN blocks, NxN / 2 blocks, N / 4xN blocks, and NxN / 4 blocks. The video encoder 200 and video decoder 300 can perform separate prediction and transform processing for each decoded block.

[0051] AV1 also defines video data tiles. A tile is a rectangular array of superblocks that can be decoded independently of other tiles. That is, the video encoder 200 and video decoder 300 can encode and decode the decoding blocks within a tile separately without using video data from other tiles. However, the video encoder 200 and video decoder 300 can perform filtering across tile boundaries. The tile size can be uniform or non-uniform. Tile-based decoding enables parallel processing and / or multithreading in the encoder and decoder implementations.

[0052] In some examples, the video encoder 200 and the video decoder 300 may use a single QTBT or MTT structure to represent each of the luma and chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT / MTT structure for the luma component and another QTBT / MTT structure for the two chroma components (or two QTBT / MTT structures for the respective chroma components).

[0053] The video encoder 200 and the video decoder 300 can be configured to use quadtree partitioning, QTBT partitioning, MTT partitioning, superblock partitioning or other partitioning structures.

[0054] In some examples, a CTU includes a decoded tree block (CTB) of luminance samples, two corresponding CTBs of chrominance samples of an image with three sample arrays, or a CTB of samples of an image decoded using three separate color planes and a syntax structure for decoding the samples. A CTB can be an NxN sample block of some value N, such that a partitioning method divides the components into CTBs. A component is an array or a single sample from one of the three arrays (luminance and two chrominance) constituting a 4:2:0, 4:2:2, or 4:4:4 color format image, or an array or a single sample constituting an array or array constituting a monochrome format image. In some examples, a decoded block is an MxN sample block of values ​​M and N, such that a partitioning method divides the CTB into decoded blocks.

[0055] Blocks (e.g., CTUs or CUs) can be grouped in various ways within an image. As an example, a brick can refer to a rectangular area of ​​a row of CTUs within a specific tile in an image. A tile can be a rectangular area of ​​CTUs within a specific tile column and a specific tile row in an image. A tile column refers to a rectangular area of ​​a CTU having a height equal to the height of the image and a width specified by syntax elements (e.g., such as in an image parameter set). A tile row refers to a rectangular area of ​​a CTU having a height specified by syntax elements (e.g., such as in an image parameter set) and a width equal to the width of the image.

[0056] In some examples, a tile can be divided into multiple bricks, each brick comprising one or more CTU rows within the tile. A tile that is not divided into multiple bricks can also be called a brick. However, bricks that are a true subset of a tile cannot be called a tile. Bricks in an image can also be arranged in slices. A slice can be an integer number of bricks in an image that can be uniquely contained within a single Network Abstraction Layer (NAL) unit. In some examples, a slice comprises multiple complete tiles or a consecutive sequence of complete bricks comprising only one tile.

[0057] This disclosure uses "NxN" and "N by N" interchangeably to refer to the sample size of a block (such as a CU or other video block) in the vertical and horizontal dimensions, for example, 16x16 samples or 16 by 16 samples. Generally, a 16x16 CU will have 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Similarly, an NxNCU typically has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non-negative integer value. Samples in a CU can be arranged in rows and columns. Furthermore, a CU does not necessarily need to have the same number of samples in the horizontal direction as it does in the vertical direction. For example, a CU may include NxM samples, where M is not necessarily equal to N.

[0058] The video encoder 200 encodes video data representing prediction and / or residual information, as well as other information, for use in the control unit (CU). The prediction information indicates how the CU should be predicted to form a prediction block for the CU. The residual information typically represents the sample-by-sample difference between a sample of the CU before encoding and the prediction block.

[0059] To predict the Cubic Frame (CU), the video encoder 200 typically forms prediction blocks for the CU through inter-frame prediction or intra-frame prediction. Inter-frame prediction typically refers to predicting the CU from data in a previously decoded image, while intra-frame prediction typically refers to predicting the CU from data in a previously decoded image within the same frame. To perform inter-frame prediction, the video encoder 200 can use one or more motion vectors to generate prediction blocks. The video encoder 200 can typically perform a motion search to identify reference blocks that closely match the CU, for example, based on the differences between the CU and a reference block. The video encoder 200 can use sum of absolute differences (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared difference (MSD), or other such difference calculations to compute difference metrics to determine whether a reference block closely matches the current CU. In some examples, the video encoder 200 can use unidirectional or bidirectional prediction to predict the current CU.

[0060] Some examples of VVC also provide an affine motion compensation mode, which can be viewed as an inter-frame prediction mode. In affine motion compensation mode, the video encoder 200 can determine two or more motion vectors representing non-translational motion, such as zooming in or out, rotation, perspective motion, or other irregular motion types.

[0061] To perform intra-frame prediction, the video encoder 200 can select an intra-frame prediction mode to generate prediction blocks. Some examples of VVC provide sixty-seven intra-frame prediction modes, including various directional modes, as well as planar and DC modes. Typically, the video encoder 200 selects an intra-frame prediction mode that describes the neighboring samples of the current block (e.g., the block of the CU), from which it predicts samples for the current block. Assuming the video encoder 200 decodes the CTU and CU in raster scan order (from left to right, from top to bottom), such samples are typically located above, to the upper left, or to the left of the current block within the same frame as the current block.

[0062] The video encoder 200 encodes data representing the prediction mode of the current block. For example, for inter-frame prediction modes, the video encoder 200 may encode data indicating which of the various available inter-frame prediction modes is used, as well as the motion information for the corresponding mode. For example, for unidirectional or bidirectional inter-frame prediction, the video encoder 200 may encode motion vectors using Advanced Motion Vector Prediction (AMVP) or merging modes. The video encoder 200 may use similar modes to encode motion vectors used for affine motion compensation modes.

[0063] AV1 includes two common techniques for encoding and decoding blocks of video data. These two common techniques are intra-frame prediction (e.g., intra-frame prediction or spatial prediction) and inter-frame prediction (e.g., inter-frame prediction or temporal prediction). In the context of AV1, when using intra-frame prediction modes to predict blocks of video data for the current frame, the video encoder 200 and video decoder 300 do not use video data from other frames of the video data. For most intra-frame prediction modes, the video encoder 200 encodes blocks of the current frame based on the difference between sample values ​​in the current block and predicted values ​​generated from reference samples in the same frame. The video encoder 200 determines the predicted values ​​generated from the reference samples based on the intra-frame prediction mode.

[0064] After prediction (such as intra-frame or inter-frame prediction for a block), the video encoder 200 can compute residual data for the block. The residual data (such as a residual block) represents the sample-by-sample difference between the block and the prediction block used to form the block, which is formed using the corresponding prediction mode. The video encoder 200 can apply one or more transforms to the residual block to produce transformed data in the transform domain rather than the sample domain. For example, the video encoder 200 can apply a Discrete Cosine Transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. Additionally, the video encoder 200 can apply a secondary transform after the first transform, such as the Mode Correlated Inseparable Secondary Transform (MDNSST), the Signal Correlation Transform, the Karhunen-Loeve Transform (KLT), etc. The video encoder 200 produces transform coefficients after applying one or more transforms.

[0065] As noted above, after any transformation that produces the transform coefficients, the video encoder 200 may perform quantization on the transform coefficients. Quantization generally refers to a process in which the transform coefficients are quantized to reduce the amount of data used to represent them, thereby providing further compression. By performing the quantization process, the video encoder 200 may reduce the bit depth associated with some or all of the transform coefficients. For example, the video encoder 200 may round an n-bit value down to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, the video encoder 200 may perform a bitwise right shift on the value to be quantized.

[0066] After quantization, the video encoder 200 can scan the transform coefficients to generate a one-dimensional vector from a two-dimensional matrix containing the quantized transform coefficients. The scan can be designed to place higher-energy (and therefore lower-frequency) transform coefficients before the vector and lower-energy (and therefore higher-frequency) transform coefficients after the vector. In some examples, the video encoder 200 can utilize a predefined scan order to scan the quantized transform coefficients to produce a serialized vector, and then entropy-encode the quantized transform coefficients of that vector. In other examples, the video encoder 200 can perform an adaptive scan. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 can entropy-encode the one-dimensional vector, for example, according to context-adaptive binary arithmetic decoding (CABAC). The video encoder 200 can also entropy-encode the values ​​of syntax elements describing metadata associated with the encoded video data, which is used by the video decoder 300 when decoding the video data.

[0067] To perform CABAC, the video encoder 200 can assign context within a context model to the symbols to be transmitted. Context may involve, for example, whether the neighboring values ​​of a symbol are zero. Probability determination can be based on the context assigned to the symbols.

[0068] The video encoder 200 may further generate syntax data for the video decoder 300, such as block-based syntax data, image-based syntax data, and sequence-based syntax data, for example, in image headers, block headers, and slice headers, or generate other syntax data such as sequence parameter sets (SPS), image parameter sets (PPS), or video parameter sets (VPS). The video decoder 300 may also decode such syntax data to determine how to decode the corresponding video data.

[0069] In this way, the video encoder 200 can generate a bitstream that includes encoded video data, such as syntax elements describing the partitioning of images into blocks (e.g., CUs) and prediction and / or residual information for the blocks. Finally, the video decoder 300 can receive the bitstream and decode the encoded video data.

[0070] Typically, the video decoder 300 performs the reverse process of the video encoder 200 to decode the encoded video data of the bitstream. For example, the video decoder 300 can use CABAC to decode the values ​​of syntax elements used for the bitstream in a manner substantially similar to, but reversed, the CABAC encoding process of the video encoder 200. Syntax elements can define partitioning information for dividing a picture into CTUs and for partitioning each CTU according to a corresponding partitioning structure such as a QTBT structure to define the CUs of the CTU. Syntax elements can further define prediction and residual information for video data blocks (e.g., CUs).

[0071] The residual information can be represented, for example, by quantized transform coefficients. The video decoder 300 can inversely quantize and inverse transform the quantized transform coefficients of the block to reconstruct the residual block for the block. The video decoder 300 uses a signaling prediction mode (intra-frame prediction or inter-frame prediction) and associated prediction information (e.g., motion information for inter-frame prediction) to form a prediction block for the block. The video decoder 300 can then combine the prediction block and the residual block (on a sample-by-sample basis) to reconstruct the original block. The video decoder 300 can perform additional processing, such as performing a deblocking process to reduce visual artifacts along the block boundaries.

[0072] This disclosure may generally relate to "signaling" certain information (such as syntax elements). The term "signaling" can generally refer to the communication of values ​​and / or other data of syntax elements used to decode encoded video data. That is, video encoder 200 may signal the values ​​of syntax elements in the bitstream. Generally, signaling refers to generating values ​​in the bitstream. As noted above, source device 102 may transmit the bitstream to destination device 116 substantially in real time or not in real time (such as when syntax elements are stored in storage device 112 for later retrieval by destination device 116).

[0073] The video encoder 200 and video decoder 300 can be configured to perform luma mapping and chroma scaling, as in VVC. VVC has a tool called Luma Mapping and Chroma Scaling (LMCS). LMCS is designed to better utilize the range of luma code values ​​allowed at a given bit depth. Figure 2 As shown, the LMCS has two main components: 1) a process for mapping input luminance code values ​​to a new set of code values ​​for use within the decoding loop; and 2) a luminance-dependent process for scaling chroma residual values. The first process (luminance mapping) aims to improve the decoding efficiency of standard and high dynamic range video signals by better utilizing the range of luminance code values ​​allowed at a given bit depth. The second process (chroma scaling) manages the relative compression efficiency of the luminance and chroma components of the video signal. The luminance mapping process in the LMCS is applied at the pixel sample level and implemented using a piecewise linear model. The chroma scaling process is applied at the chroma block level and implemented using a scaling factor derived from the reconstructed neighboring luminance samples of the chroma block.

[0074] exist Figure 2 The decoding architecture of LMCS is illustrated in the figure. Figure 2 The upper 140 illustrates the chromaticity residual scaling component of LMCS. Figure 2The lower 154 illustrates the luminance mapping component of LMCS. LMCS introduces the concept of a signal in either the "mapped domain" or the "original (unmapped signal) domain." The luminance code values ​​of the video signal in the mapped domain processed by LMCS may differ from those of the original video signal in the original domain. When LMCS is enabled, the signal in the mapped domain is processed... Figure 2 Functional blocks 156 to 160. These blocks include inverse quantization (Q-1) and inverse transform (T-1) 156, intra-frame luminance prediction 160, and summation of luminance prediction and luminance residual values ​​(reconstruction 158). Figure 2 The shadowless blocks in the image indicate that processing is applied in the original (unmapped) domain. Such blocks include loop filters 148, 164 (e.g., deblocking, adaptive loop filter (ALF), and sample adaptive offset (SAO)), motion-compensated prediction (motion compensation 168), intra-frame chroma prediction (intra-frame prediction 146), summing the chroma prediction and chroma residual values ​​(reconstruction 158), and storing the image in a decoded image buffer (DPB 150, 166).

[0075] The video encoder 200 and video decoder 300 can be configured to utilize motion-compensated temporal filters (motion compensation 152, 168). A motion-compensated temporal bilateral denoising filter (MCTF) is used as a pre-filter in the VVC to reduce noise in the sequence. The filtering process (loop filters 148, 164) is applied before encoding and uses neighboring images. The filtering parameters for the current image depend on the neighboring images, the current image's location within a group of pictures (GOP), and the values ​​of the quantization parameters (QP). The filters are designed for both random access and low-latency configurations. For the low-latency configuration, subsequent images are now available but not used. For the intra-frame configuration, the MCTF is disabled.

[0076] The MCTF-filtered sequence is treated as input and fed to the encoder for encoding. The filtered sequence is used in bit rate distortion performance to select the optimal decoding mode during the encoding process. Due to filtering, the distribution and dynamic range of the MCTF-filtered image differ slightly from the original data in the YUV file.

[0077] In the current draft of the ECM for the encoder and decoder (M. Coban, F. Le Léannec, and J. Ström, “Algorithm description of Enhanced Compression Model 2 (ECM 2)” JVET-W2025, July 2021), bit-depth-based cropping is used at different locations to avoid data overflow. The bit-depth dynamic range of the image is defined as [0, 2^bit depth - 1]. When a sample value is less than 0, it can be cropped to 0. When a sample value is greater than 2^bit depth - 1, it can be cropped to 2^bit depth - 1. This cropping step is mandatory in filtering, weighted prediction, weighted combination, reconstruction, and other stages to ensure that the resulting predicted and reconstructed samples remain within a defined dynamic range. However, bit-depth-based dynamic range cropping ignores the characteristics and statistics of images and sequences, making it inefficient and inaccurate.

[0078] This disclosure describes techniques for using adaptive clipping ranges and associated signaling, including, where applicable, domain mapping for the clipping range. The disclosed techniques may be used alone or in any combination.

[0079] This disclosure defines an adaptive cropping with lower and upper limits for signaling, which provides more accurate cropping that takes into account the image content and improves decoding efficiency.

[0080] Video encoder 200 and video decoder 300 can be configured to perform adaptive cropping with signaled lower and upper limits. In some examples, video encoder 200 and video decoder 300 can be configured to apply adaptive cropping with signaled lower and upper limits. For each encoded image, in one example, the minimum and maximum values ​​[Imin, Imax] of the color channels are obtained by scanning all samples from the image buffer. A set of lower and upper limits [Imin, Imax] can be signaled, for example, in the image header. When the cropping process is performed in the encoding and decoding pipeline, the original bit-depth-based cropping range [0, 2^bit depth - 1] can be replaced with the signaled lower and upper limits [Imin, Imax]. If a sample value is less than the lower limit Imin, the sample value can be cropped to Imin. If a sample value is greater than the upper limit Imax, the sample value can be cropped to Imax.

[0081] In some examples, only the lower or upper limit is signaled, and the other may be fixed to a depth of 2^bit - 1 or 0, or may not be used at all.

[0082] Video encoder 200 and video decoder 300 can be configured to apply adaptive cropping. In some examples, video encoder 200 and video decoder 300 can be configured to apply adaptive cropping when the encoder or decoder derives predicted samples, reconstructed samples, or derived values ​​multiplied by a scaling factor (e.g., in the reconstruction step when adding residual signals to prediction, filtering, ALF, deblocking (DB), SAO, upsampling, downsampling, reference image resampling (RPR) and scaling, cross-component prediction, weighted combination of different prediction factors, weighted prediction, prediction multiplied by a scaling factor, weighted blending at edges).

[0083] In another example, the video encoder 200 and video decoder 300 can be configured to apply adaptive cropping to a subset of locations / modes where cropping is required. For other locations where cropping is required, bit-depth-based cropping is applied. For example, adaptive cropping can be applied to all or a subset of the following: during the reconstruction step (e.g., when adding the residual signal to the prediction), during deblocking filtering, during bilateral filtering, during the ALF process, and after the ALF process (e.g., before storing in the decoded image buffer). For other modes and locations, bit-depth-based cropping can be applied.

[0084] In some examples, the video encoder 200 and video decoder 300 can be configured to apply adaptive cropping to one, some, or all of the color channels. If adaptive cropping is not applied to all color channels, bit-depth-based cropping is applied to the remaining color channels. For example, adaptive cropping may be applied only to the luminance component.

[0085] In some examples, the adaptive cropping techniques described herein can be combined and applied differently based on image type or slice type. For example, for I-slices and B-slices, cropping can be applied to the reconstruction step after the ALF process. For low-latency B (LDB) LDB images, cropping can be applied only after the ALF process. By definition, an LDB image is defined as an image that has all reference images from the past (or with smaller POC numbers) compared to the current image.

[0086] In some examples, the techniques described herein can be applied to the displayable area of ​​a compressed image (of the same size as the input image).

[0087] In some examples, the techniques described herein can be applied to extended regions of the image. For instance, when the boundary filling process is applied to the image, the techniques described herein can be used to crop the values ​​of samples within the filled regions.

[0088] The video encoder 200 and video decoder 300 can be configured to perform signaling related to adaptive cropping. In one example, the minimum and maximum values ​​[Imin, Imax] of the color channels in an image are signaled in one or more VPS, SPS, PPS, picture, or slice headers. In one example, signed or unsigned binarization or codewords can be used, such as unsigned variable-length decoding.

[0089] In another example, the minimum and maximum values ​​[Imin, Imax] of the color channels in the image can be quantized, for example, by right-shifting by N bits, and then signaled. In the example above, during decoding, the signaled value is dequantized, and left-shifted by N bits is used to process the signaled value to reconstruct the corresponding lower and upper limits.

[0090] In some examples, the quantization parameter can be a predetermined integer value. In some examples, the quantization parameter value can be derived from a function of the bit depth, such as from a predetermined table that uses the bit depth as an index. In some examples, the quantization parameter can have predetermined values ​​for each color channel type. In some examples, the quantization parameter value N can be used for all images in the sequence.

[0091] In some examples, the quantization parameter value Nx can be used for specific image types. For instance, the quantization parameter value N0 can be used for I images, the quantization parameter value N1 for B images, the quantization parameter value N2 for P images, and the quantization parameter value N3 for LDB images. Furthermore, given an example of an LDB image, how an LDB image might be defined might be that, compared to the current image, all reference images are from the past (or have smaller POC numbers).

[0092] In some examples, quantization parameter values ​​can be signaled in one or more parameter sets, such as VPS, SPS, PPS, image, or slice headers with or without signed binarization or codewords. For example, a signaled quantization parameter value in an SPS can be used for all images in a sequence (or a segment of a sequence). Similarly, a signaled quantization parameter value in an image or slice header can be used for that image.

[0093] In another example, as previously described, the difference between the minimum / maximum value [Imin, Imax] and the predictor is signaled in one of the parameter sets and / or headers. In one example, the predictor may be set equal to the standard narrow dynamic range [Smin, Smax] (Smin = 64, Smax = 940 for luminance, Smax = 960 for chrominance). In another example, the predictor may be signaled. Signed binarization (e.g., signed variable-length decoding) may be used to signal the difference between the range and the predictor. That is, in one example, Imin – Smin and Imax – Smax are signaled in the image header using signed variable-length decoding. In some examples, the quantized Δ values ​​Imin – Smin and Imax – Smax may be signaled in the image header, where the quantization parameters are predetermined, signaled, or derived from a predetermined lookup table indexed by bit depth or color channel type.

[0094] In one example, for the I slice, the minimum and maximum values ​​[Imin, Imax] of the signaling color channels are obtained as described above. For the P or B slice, a sign-variable length decoder is used to signal the difference between the signaling values ​​and those of the previous I slice.

[0095] In another example, the aforementioned predictor can be signaled in one or more parameter sets (e.g., in an SPS or VPS), and then each slice or image (e.g., in a slice or image header) can be signaled for the difference between the range value and its predictor.

[0096] In another example, the min / max value predictor is signaled in the SPS, and for P-slice or B-slice types, the difference between the range value and the predictor is signaled in the slice header, and this difference is inferred to be equal to 0 if no signaling is performed for I-slices.

[0097] In some examples, the min / max predictor values ​​are signaled in the SPS, and to avoid repeated signaling in the slice headers of multiple inter-frame slices of the same image when an I-slice is not present, the flag value of `ph_intra_slice_allowed_flag`, indicating whether an I-slice is possible in the image, is checked. If `ph_intra_slice_allowed_flag` equals 0, the difference is signaled in the image header; and if `ph_intra_slice_allowed_flag` equals 0, the difference is not signaled in the slice header; and if `ph_intra_slice_allowed_flag` equals 1, and the slice type is either a P-slice or a B-slice, the difference is signaled in the slice header; and if `ph_intra_slice_allowed_flag` equals 1, the difference is not signaled in the image header. For I-slices, the difference is inferred to be 0 if no signal is given.

[0098] In another alternative or supplement, the image type can be examined, and based on that examination, it can be determined whether the difference is signaled, for example, in the slice header or the image header. In one example, the range predictor is signaled in the SPS, and if the image type is IRAP (which is generally signaled via SPS), it might be impossible to infer that the difference would be equal to 0 without signaling. Furthermore, for non-IRAP images, the difference between the cropped range and the range predictor (signed in the SPS) in one example signals the difference between the min value and the min value predictor, as well as the difference between the max value and the max value predictor.

[0099] Another example of signaling minimum / maximum values ​​is using the co-located image minimum / maximum values ​​as predictor values, and signaling the difference from the predictor values ​​only in the slice or image header. This signaling can be applied, for example, to inter-frame slices such as B-slices or P-slices. In some examples, the quantized difference can be signaled in the slice or image header, where the quantization process is one of the quantization processes described herein or any combination thereof.

[0100] In some examples, a flag is signaled in one or more parameter sets to indicate whether to signal the [min, max] pair for the corresponding image or slice. If the flag indicates not to signal [min, max], then default min and max are used, for example, min and max values ​​determined by the bit depth.

[0101] In some examples, the absolute value of the difference between the range value and the predictor is constrained to be less than a threshold. Examples of thresholds are 16, 32, 64, 128, etc. Fixed-length decoding can then be applied to decode the difference.

[0102] In some examples, a set of [min, max] pairs is signaled in the Adaptive Parameter Set (APS), and indices are signaled at the image header, image parameter set, slice header, or block level to indicate the [min, max] pairs within the APS and for the image, slice, or block (e.g., CTU). Each [min, max] pair in this set can be predicted by a standard narrow dynamic range or a predictor as described above, and the difference is signaled.

[0103] The video encoder 200 and video decoder 300 can be configured to perform adaptive cropping when preprocessing is enabled. When preprocessing is enabled (MCTF in one example), both the luminance and chroma channels of the image can be pre-filtered before encoding. This may result in a different dynamic range for such an image compared to the original unfiltered image. The video encoder 200 and video decoder 300 can be configured to obtain the minimum and maximum values ​​[Imin_mctf, Imax_mctf] of the color channel by scanning all pixel samples in the MCTF image buffer of the color channel when MCTF is enabled. This set of ranges [Imin_mctf, Imax_mctf] can be signaled, for example, using any signaling technique described herein.

[0104] In one example, the preprocessed range (min and max values) can be signaled instead of the original range. In another example, any of the signaling techniques described herein can be used to additionally signal the preprocessed range.

[0105] In some examples, when both the preprocessed range and the original range are signaled, these two ranges can be used for cropping at certain locations and operations in the encoder and decoder. The reconstructed image is cropped within the original range when used for display or quality evaluation. The reconstructed image is cropped within the preprocessed range and subsequently used as a reference image for encoding and decoding other images.

[0106] Video encoder 200 and video decoder 300 can be configured to perform adaptive cropping when domain mapping is applied. When domain mapping is applied to an image, sample values ​​in one domain can be converted to values ​​in another domain and processed in the mapped domain. Some processing steps and patterns can operate in the mapped domain, while others can operate in the original domain. Look-up tables (LUTs) or predefined mapping functions can be used to transform the original and mapped domains. In some examples, it is proposed to map lower and upper bounds to the corresponding domains (e.g., from the original domain to the mapped domain), and then apply cropping with the corresponding mapped lower and upper bounds. In one example, this mapping is performed against the luminance chrominance components in the LMCS. If scaling is enabled, for example, against the chrominance components in the LMCS, the lower and upper bounds can be multiplied by a scaling factor. Cropping is then performed using the scaled lower and upper bounds.

[0107] In one example, the detailed steps for applying the mapped and scaled crop limits in LMCS are as follows. First, the lower and upper limits [Imin, Imax] of the color channels in the image are obtained from the image buffer (or [Imin_mctf, Imax_mctf] from the MCTF image buffer if MCTF is enabled). The lower and upper limits can be signaled using any signaling techniques described herein. When applying cropping, for the luma channel, the video decoder 300 first checks two conditions: 1) whether LMCS is enabled, and 2) whether the current cropping location (mode) is in the original domain or the mapped domain. If LMCS is enabled and the current cropping is in the mapped domain, the lower and upper limits [Imin, Imax] are mapped to the mapped domain as [I′min, I′max] using an LMCS forward mapping LUT. Then, the luma channel is cropped for that location (mode) using these mapped lower and upper limits.

[0108] For the chroma channel, the video decoder 300 first checks the following two conditions: 1) whether LMCS is enabled, and 2) whether chroma scaling is enabled and what the scaling factor is. If LMCS and chroma scaling are enabled, the lower and upper limits [Imin, Imax] of the chroma channel are multiplied by the scaling factor [a] using the LMCS chroma scaling factor a. Imin, a [Imax]. Then, use the lower and upper bounds of this scaling to crop the chroma channel for that positioning (mode).

[0109] In some examples, when weighting / combining multiple predicted or reconstructed values ​​from different domains, the predicted / reconstructed value is first pruned using the pruning range of the domain in which each prediction / reconstruction resides. Then, such predictions / reconstructions are mapped to the same domain, and the pruning within that domain's range is applied to the weighted / combined predictions or reconstructions.

[0110] Figure 3 This is a block diagram illustrating an example video encoder 200 that can perform the techniques of this disclosure. Figure 3 This disclosure is provided for illustrative purposes and should not be construed as a limitation on the techniques extensively illustrated and described herein. For illustrative purposes, this disclosure describes the video encoder 200 in accordance with the techniques of VVC and HEVC. However, the techniques of this disclosure can be performed by video encoding devices configured for other video decoding standards and video decoding formats, such as AV1 and subsequent formats of AV1 video decoding.

[0111] exist Figure 3 In the example, the video encoder 200 includes a video data memory 230, a mode selection unit 202, a residual generation 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 filter unit 216, a decoded picture buffer (DPB) 218, and an entropy coding unit 220. Any or all of the video data memory 230, mode selection unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, filter unit 216, DPB 218, and entropy coding unit 220 may be implemented in one or more processors or in processing circuitry. For example, the units of the video encoder 200 may be implemented as one or more circuit or logic elements as part of hardware circuitry, or as part of a processor, ASIC, or FPGA. Furthermore, the video encoder 200 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0112] Video data storage 230 is an example of a storage system capable of storing video data to be encoded by components of video encoder 200. Video encoder 200 can receive data from, for example, video source 104 (…). Figure 1The video data memory 230 receives video data stored in the video data memory 230. The DPB 218 is an example of a memory system that can act as a reference picture memory, storing reference video data for use when the video encoder 200 predicts subsequent video data. The video data memory 230 and DPB 218 can each be formed from any of one or more memory devices or memory cells, such as dynamic random access memory (DRAM) (including synchronous DRAM (SDRAM)), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The video data memory 230 and DPB 218 can be provided by the same memory device or separate memory devices. In various examples, the video data memory 230 can be on-chip (as illustrated) with other components of the video encoder 200, or off-chip relative to those components.

[0113] In this disclosure, references to video data memory 230 should not be construed as limited to memory inside video encoder 200 (unless specifically described) or memory outside video encoder 200 (unless specifically described). Rather, references to video data memory 230 should be understood as a reference memory that stores video data received by video encoder 200 for encoding (e.g., video data for the current block to be encoded). Figure 1 The memory 106 can also provide temporary storage for the outputs from various units of the video encoder 200.

[0114] Examples Figure 3 Various units help understand the operations performed by the video encoder 200. Units can be implemented as fixed-function circuits, programmable circuits, or combinations thereof. Fixed-function circuits are circuits that provide specific functionality and are pre-defined for the operations that can be performed. Programmable circuits are circuits that can be programmed to perform various tasks and provide flexible functionality for the operations that can be performed. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (e.g., to receive or output parameters), but the type of operation performed by a fixed-function circuit is generally immutable. In some examples, one or more units in the unit may be different circuit blocks (fixed-function or programmable), and in some examples, one or more units in the unit may be integrated circuits.

[0115] The video encoder 200 may include an arithmetic logic unit (ALU), an essential function unit (EFU), digital circuitry, analog circuitry, and / or a programmable core, all formed by programmable circuitry. In an example where the operation of the video encoder 200 is performed using software executed by programmable circuitry, memory 106 ( Figure 1 The video encoder 200 may store instructions (e.g., target code) of the software received and executed by the video encoder 200, or another memory (not shown) within the video encoder 200 may store such instructions.

[0116] The video data storage unit 230 is configured to store received video data. The video encoder 200 can retrieve images of the video data from the video data storage unit 230 and provide the video data to the residual generation unit 204 and the mode selection unit 202. The video data in the video data storage unit 230 can be raw video data to be encoded.

[0117] The mode selection unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra-frame prediction unit 226. The mode selection unit 202 may include additional functional units for performing video prediction based on other prediction modes. As an example, the mode selection unit 202 may include a palette unit, an intra-frame block copying unit (which may be part of the motion estimation unit 222 and / or the motion compensation unit 224), an affine unit, a linear model (LM) unit, etc.

[0118] Mode selection unit 202 typically coordinates multiple coding channels to test combinations of coding parameters and the resulting rate-distortion values ​​for such combinations. Coding parameters may include the CTU-CU partitioning, the prediction mode for the CU, the transformation type of the residual data for the CU, the quantization parameters of the residual data for the CU, etc. Mode selection unit 202 can ultimately select a combination of coding parameters that has a better rate-distortion value compared to other tested combinations.

[0119] The video encoder 200 can divide an image retrieved from the video data storage 230 into a series of CTUs and encapsulate one or more CTUs within a slice. The mode selection unit 202 can divide the image's CTUs according to the tree structure described above (such as an MTT structure, QTBT structure, superblock structure, or the quadtree structure described above). As described above, the video encoder 200 can form one or more CUs by dividing the CTUs according to the tree structure. Such CUs are also commonly referred to as "video blocks" or "blocks".

[0120] Typically, mode selection unit 202 also controls its components (e.g., motion estimation unit 222, motion compensation unit 224, and intra-prediction unit 226) to generate prediction blocks for the current block (e.g., the current CU, or, in HEVC, the overlapping portion of PU and TU). To perform inter-frame prediction for the current block, motion estimation unit 222 may perform a motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously decoded pictures stored in DPB 218). Specifically, motion estimation unit 222 may calculate values ​​representing the similarity between a potential reference block and the current block, for example, based on sum of absolute differences (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared difference (MSD), etc. Motion estimation unit 222 may typically perform these calculations using sample-by-sample differences between the current block and the reference blocks under consideration. Motion estimation unit 222 may identify reference blocks with the lowest values ​​produced by these calculations to indicate the reference block that best matches the current block.

[0121] Motion estimation unit 222 can generate one or more motion vectors (MVs) that define the location of a reference block in a reference image relative to the location of the current block in the current image. Motion estimation unit 222 can then provide the motion vectors to motion compensation unit 224. For example, for unidirectional inter-frame prediction, motion estimation unit 222 can provide a single motion vector, while for bidirectional inter-frame prediction, motion estimation unit 222 can provide two motion vectors. Motion compensation unit 224 can then use the motion vectors to generate a prediction block. For example, motion compensation unit 224 can use the motion vectors to retrieve data for the reference block. As another example, if the motion vectors have fractional sample accuracy, motion compensation unit 224 can interpolate the prediction block according to one or more interpolation filters. Furthermore, for bidirectional inter-frame prediction, motion compensation unit 224 can retrieve data for two reference blocks identified by corresponding motion vectors and combine the retrieved data, for example, by per-sample averaging or weighted averaging.

[0122] When operating according to the AV1 video decoding format, the motion estimation unit 222 and the motion compensation unit 224 can be configured to encode the decoded blocks of video data (e.g., both luma and chroma decoded blocks) using translational motion compensation, affine motion compensation, overlap block motion compensation (OBMC), and / or composite inter-intra-frame prediction.

[0123] As another example, for intra-prediction or intra-prediction decoding, intra-prediction unit 226 may generate a prediction block from samples adjacent to the current block. For example, for directional mode, intra-prediction unit 226 may typically mathematically combine the values ​​of adjacent samples and fill these calculated values ​​across the current block in a defined direction to produce a prediction block. As another example, for DC mode, intra-prediction unit 226 may calculate the average of the adjacent samples of the current block and generate a prediction block to include the resulting average for each sample of the prediction block.

[0124] When operating according to the AV1 video decoding format, the intra-frame prediction unit 226 can be configured to encode decoded blocks of video data (e.g., both luma and chroma decoded blocks) using directional intra-frame prediction, non-directional intra-frame prediction, recursive filter intra-frame prediction, luma-chroma (CFL) prediction, intra-block copying (IBC), and / or palette modes. The mode selection unit 202 may include additional functional units for performing video prediction based on other prediction modes.

[0125] Mode selection unit 202 provides a prediction block to residual generation unit 204. Residual generation unit 204 receives an uncoded raw version of the current block from video data memory 230 and a prediction block from mode selection unit 202. Residual generation unit 204 calculates the sample-by-sample difference between the current block and the prediction block. The resulting sample-by-sample difference defines the residual block for the current block. In some examples, residual generation unit 204 may also determine the differences between sample values ​​in the residual block to generate the residual block using residual differential pulse decoding modulation (RDPCM). In some examples, residual generation unit 204 may be formed using one or more subtractor circuits performing binary subtraction.

[0126] In the example where mode selection unit 202 divides a CU into PUs, each PU can be associated with a luma prediction unit and a corresponding chroma prediction unit. Video encoder 200 and video decoder 300 can support PUs of various sizes. As noted above, the size of a CU can refer to the size of the luma decoding block of the CU, while the size of a PU can refer to the size of the luma prediction unit of the PU. Assuming a particular CU size is 2Nx2N, video encoder 200 can support PU sizes of 2Nx2N or NxN for intra-frame prediction, and symmetric PU sizes of 2Nx2N, 2NxN, Nx2N, NxN, or similar for inter-frame prediction. Video encoder 200 and video decoder 300 can also support asymmetric partitioning for PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter-frame prediction.

[0127] In an example where mode selection unit 202 does not further divide the CU into PUs, each CU can be associated with a luminance decoding block and a corresponding chrominance decoding block. As mentioned above, the size of the CU can refer to the size of the luminance decoding block of the CU. The video encoder 200 and the video decoder 300 can support CU sizes of 2Nx2N, 2NxN, or Nx2N.

[0128] For other video decoding techniques, such as intra-block copy mode decoding, affine mode decoding, and linear model (LM) mode decoding, as some examples, mode selection unit 202 generates a prediction block for the current block being encoded via a corresponding unit associated with the decoding technique. In some examples (such as palette mode decoding), mode selection unit 202 may not generate a prediction block, but instead generate syntax elements indicating how the block is reconstructed based on a selected palette. In such modes, mode selection unit 202 may provide these syntax elements to entropy coding unit 220 for encoding.

[0129] As described above, the residual generation unit 204 receives video data for the current block and the corresponding prediction block. Then, the residual generation unit 204 generates a residual block for the current block. To generate the residual block, the residual generation unit 204 calculates the sample-by-sample difference between the prediction block and the current block.

[0130] Transform processing unit 206 applies one or more transformations to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). Transform processing unit 206 may apply various transformations to the residual block to form the transform coefficient block. For example, transform processing unit 206 may apply a discrete cosine transform (DCT), direction transform, Karhunen-Loeve transform (KLT), or conceptually similar transformations to the residual block. In some examples, transform processing unit 206 may perform multiple transformations on the residual block, such as primary and secondary transformations (e.g., rotation transformations). In some examples, transform processing unit 206 does not apply any transformations to the residual block.

[0131] When operating according to AV1, transform processing unit 206 may apply one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). Transform processing unit 206 may apply various transforms to the residual block to form the transform coefficient block. For example, transform processing unit 206 may apply a combination of horizontal / vertical transforms, which may include the Discrete Cosine Transform (DCT), the Asymmetric Discrete Sine Transform (ADST), the Reversed ADST (e.g., ADST in reverse order), and the Identity Transform (IDTX). When using the Identity Transform, the transform is skipped in either the vertical or horizontal direction. In some examples, transform processing may be skipped entirely.

[0132] Quantization unit 208 quantizes the transform coefficients in a transform coefficient block to produce a quantized transform coefficient block. Quantization unit 208 quantizes the transform coefficients of the transform coefficient block according to the quantization parameter (QP) value associated with the current block. Video encoder 200 (e.g., via mode selection unit 202) can adjust the degree of quantization applied to the transform coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may cause information loss, and therefore, the quantized transform coefficients may have lower accuracy compared to the original transform coefficients produced by transform processing unit 206.

[0133] The inverse quantization unit 210 and the inverse transform processing unit 212 can apply inverse quantization and inverse transform, respectively, to the quantized transform coefficient block to reconstruct the residual block based on the transform coefficient block. The reconstruction unit 214 can generate a reconstructed block corresponding to the current block (although potentially with some degree of distortion) based on the reconstructed residual block and the prediction block generated by the mode selection unit 202. For example, the reconstruction unit 214 can add samples of the reconstructed residual block to corresponding samples of the prediction block generated by the mode selection unit 202 to generate the reconstructed block.

[0134] Filter unit 216 may perform one or more filtering operations on the reconstructed block. For example, filter unit 216 may perform a deblocking operation to reduce block artifacts along the edges of the CU. In some examples, the operation of filter unit 216 may be skipped.

[0135] When operating according to AV1, filter unit 216 may perform one or more filtering operations on the reconstructed block. For example, filter unit 216 may perform a deblocking operation to reduce block artifacts along the edges of the CU. In other examples, filter unit 216 may apply a constrained direction enhancement filter (CDEF) after deblocking and may include the application of a non-separable, nonlinear, low-pass directional filter based on the estimated edge direction. Filter unit 216 may also include a loop recovery filter applied after CDEF and may include a separable symmetric normalized Wiener filter or a dual-guided filter.

[0136] The video encoder 200 stores reconstructed blocks in the DPB 218. For example, in an example where the filter unit 216 is not operated, the reconstruction unit 214 may store reconstructed blocks in the DPB 218. In an example where the filter unit 216 is operated, the filter unit 216 may store filtered reconstructed blocks in the DPB 218. The motion estimation unit 222 and the motion compensation unit 224 may retrieve reference images formed by the reconstructed (and potentially filtered) blocks from the DPB 218 to perform inter-frame prediction for blocks of subsequent encoded images. Additionally, the intra-frame prediction unit 226 may use the reconstructed blocks of the current image in the DPB 218 to perform intra-frame prediction for other blocks in the current image.

[0137] Typically, entropy coding unit 220 can entropy-encode syntax elements received from other functional components of video encoder 200. For example, entropy coding unit 220 can entropy-encode quantized transform coefficient blocks from quantization unit 208. As another example, entropy coding unit 220 can entropy-encode predictive syntax elements (e.g., motion information for inter-frame prediction or intra-frame mode information for intra-frame prediction) from mode selection unit 202. Entropy coding unit 220 can perform one or more entropy coding operations on syntax elements (another example of video data) to generate entropy-coded data. For example, entropy coding unit 220 can perform context-adaptive variable-length decoding (CAVLC), CABAC, variable-to-variable (V2V) length decoding, syntax-based context-adaptive binary arithmetic decoding (SBAC), probability interval partitioning entropy (PIPE) decoding, exponential Golomb coding, or another type of entropy coding operation on the data. In some examples, entropy coding unit 220 can operate in a bypass mode where syntax elements are not entropy-encoded.

[0138] The video encoder 200 can output a bitstream that includes the entropy coding syntax elements required to reconstruct slices or blocks of images. Specifically, the entropy coding unit 220 can output a bitstream.

[0139] According to AV1, entropy coding unit 220 can be configured as a symbol-to-symbol adaptive multi-symbol arithmetic decoder. The syntax elements in AV1 consist of an N-element alphabet, and the context (e.g., a probability model) consists of a set of N probabilities. Entropy coding unit 220 can store the probabilities as an n-bit (e.g., 15-bit) cumulative distribution function (CDF). Entropy coding unit 220 can perform recursive scaling using an update factor based on the alphabet size to update the context.

[0140] The operations described above are relative to blocks. This description should be understood as operations applied to luma decoding blocks and / or chroma decoding blocks. As described above, in some examples, the luma decoding block and chroma decoding block are the luma and chroma components of the CU. In some examples, the luma decoding block and chroma decoding block are the luma and chroma components of the PU.

[0141] In some examples, it is not necessary to repeat the operations performed relative to the luma decoder for the chroma decoder block. As an example, the operations for identifying the motion vector (MV) and reference image of the luma decoder block do not need to repeat the MV and reference image used to identify the chroma block. Instead, the MV used for the luma decoder block can be scaled to determine the MV used for the chroma block, and the reference image can be the same. As another example, the intra-frame prediction process can be the same for both the luma and chroma decoders.

[0142] Video encoder 200 represents an example of a device configured to encode video data, the device including: a memory configured to store video data; and one or more processing units implemented in circuitry and configured to: determine a minimum sample value for one or more blocks of video data, the minimum sample value being greater than 0; and, in response to a process of determining a block applied to the one or more blocks of video data resulting in a sample value less than the minimum sample value, crop a sample value to the minimum sample value. The one or more processing units implemented in circuitry may alternatively or additionally be configured to: determine a maximum sample value for one or more blocks of video data, the maximum sample value being less than 2^bd - 1; and, in response to a process of determining a block applied to the one or more blocks of video data resulting in a sample value greater than the maximum sample value, crop a sample value to the maximum sample value.

[0143] Figure 4 This is a block diagram illustrating an example video decoder 300 that can perform the techniques of this disclosure. Figure 4 This disclosure is provided for illustrative purposes and not for limiting the techniques extensively illustrated and described herein. For illustrative purposes, the video decoder 300 is described in accordance with VVC and HEVC techniques. However, the techniques of this disclosure can be implemented by video decoding devices configured for other video decoding standards.

[0144] exist Figure 4In the example, the video decoder 300 includes a decoded picture buffer (CPB) memory 320, an entropy decoding unit 302, a prediction processing unit 304, an inverse quantization unit 306, an inverse transform processing unit 308, a reconstruction unit 310, a filter unit 312, and a DPB 314. Any or all of the CPB memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and DPB 314 can be implemented in one or more processors or in processing circuitry. For example, the units of the video decoder 300 can be implemented as one or more circuit or logic elements as part of hardware circuitry, or as part of a processor, ASIC, or FPGA. Furthermore, the video decoder 300 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0145] The prediction processing unit 304 includes a motion compensation unit 316 and an intra-prediction unit 318. The prediction processing unit 304 may include additional units that perform predictions based on other prediction modes. As an example, the prediction processing unit 304 may include a palette unit, an intra-block copying unit (which may form part of the motion compensation unit 316), an affine unit, a linear model (LM) unit, etc. In other examples, the video decoder 300 may include more, fewer, or different functional components.

[0146] When operating according to AV1, motion compensation unit 316 can be configured to decode video data blocks (e.g., both luma and chroma blocks) using translational motion compensation, affine motion compensation, OBMC, and / or composite inter-intra-frame prediction, as described above. Intra-frame prediction unit 318 can be configured to decode video data blocks (e.g., both luma and chroma blocks) using directional intra-frame prediction, non-directional intra-frame prediction, recursive filter intra-frame prediction, CFL, IBC, and / or palette mode, as described above.

[0147] CPB memory 320 is an example of a memory system capable of storing video data (such as encoded video bitstreams) to be decoded by components of video decoder 300. For example, it can be stored from computer-readable medium 110 ( Figure 1The video data stored in the CPB memory 320 is obtained. The CPB memory 320 may include a CPB that stores encoded video data (e.g., syntax elements) from the encoded video bitstream. Furthermore, the CPB memory 320 may store video data other than the syntax elements of the decoded image, such as temporary data representing the output from various units of the video decoder 300. The DPB 314 is an example of a memory system that typically stores a decoded image that the video decoder 300 can output, and / or uses as reference video data when decoding subsequent data or images from the encoded video bitstream. The CPB memory 320 and the DPB 314 may each be formed from any of various memory devices or memory cells, such as DRAM (including SDRAM), MRAM, RRAM, or other types of memory devices. The CPB memory 320 and the DPB 314 may be provided by the same memory device or separate memory devices. In various examples, the CPB memory 320 may be on-chip with other components of the video decoder 300, or off-chip relative to those components.

[0148] Additionally or alternatively, in some examples, the video decoder 300 may be from the memory 120 ( Figure 1 The decoded video data can be retrieved from the memory. In other words, memory 120 can utilize CPB memory 320 to store data as discussed above. Similarly, when some or all of the functionality of video decoder 300 is implemented in software to be executed by the processing circuitry of video decoder 300, memory 120 can store instructions to be executed by video decoder 300.

[0149] Examples Figure 4 The various units shown help to understand the operations performed by the video decoder 300. These units can be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Similar to... Figure 3 Fixed-function circuits are circuits that provide specific functionality and are pre-configured for the operations they can perform. Programmable circuits are circuits that can be programmed to perform various tasks and provide flexible functionality for the operations they can perform. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (e.g., to receive or output parameters), but the type of operation performed by a fixed-function circuit is typically immutable. In some examples, one or more units in a cell may be different circuit blocks (fixed-function or programmable), and in some examples, one or more units in a cell may be integrated circuits.

[0150] The video decoder 300 may include an ALU, EFU, digital circuitry, analog circuitry, and / or a programmable core formed by programmable circuitry. In an example where the operation of the video decoder 300 is performed by software executed on programmable circuitry, on-chip or off-chip memory may store instructions (e.g., object code) of the software received and executed by the video decoder 300.

[0151] The entropy decoding unit 302 can receive encoded video data from the CPB and perform entropy decoding on the video data to reproduce the syntax elements. The prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, and the filter unit 312 can generate decoded video data based on the syntax elements extracted from the bitstream.

[0152] Typically, the video decoder 300 reconstructs the image block by block. The video decoder 300 can perform the reconstruction operation on each block individually (where the block currently being reconstructed (i.e., decoded) can be referred to as the "current block").

[0153] Entropy decoding unit 302 can entropy decode the syntax elements of the quantized transform coefficients defining the quantized transform coefficient block, as well as transform information (such as quantization parameters (QP) and / or transform mode indications). Inverse quantization unit 306 can use the QP associated with the quantized transform coefficient block to determine the degree of quantization, and similarly, determine the degree of inverse quantization to be applied by inverse quantization unit 306. Inverse quantization unit 306 can, for example, perform a bit-by-bit left shift operation to inverse quantize the quantized transform coefficients. Inverse quantization unit 306 can thereby form a transform coefficient block including the transform coefficients.

[0154] After the inverse quantization unit 306 forms the transform coefficient block, the inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, the inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotation transform, an inverse direction transform, or another inverse transform to the transform coefficient block.

[0155] Furthermore, the prediction processing unit 304 generates a prediction block based on the prediction information syntax elements entropy decoded by the entropy decoding unit 302. For example, if the prediction information syntax elements indicate that the current block is an inter-frame prediction, the motion compensation unit 316 can generate the prediction block. In this case, the prediction information syntax elements may indicate the reference picture from which the reference block is to be retrieved in the DPB 314, and a motion vector identifying the position of the reference block in the reference picture relative to the position of the current block in the current picture. The motion compensation unit 316 may generally follow the same procedure as relative to the motion compensation unit 224 ( Figure 3 The method described is essentially the same as the method used to perform the inter-frame prediction process.

[0156] As another example, when the prediction information syntax element indicates that the current block is intra-predictive, intra-predictive unit 318 may generate a prediction block according to the intra-predictive mode indicated by the prediction information syntax element. Similarly, intra-predictive unit 318 may generally follow the same procedure as relative to intra-predictive unit 226 ( Figure 3 The intra-prediction process is performed in a manner substantially similar to that described above. The intra-prediction unit 318 can retrieve data of neighboring samples of the current block from the DPB 314.

[0157] Reconstruction unit 310 can use the prediction block and the residual block to reconstruct the current block. For example, reconstruction unit 310 can add samples from the residual block to the corresponding samples from the prediction block to reconstruct the current block.

[0158] Filter unit 312 can perform one or more filtering operations on the reconstructed block. For example, filter unit 312 can perform a deblocking operation to reduce block artifacts along the edges of the reconstructed block. The operation of filter unit 312 is not necessarily performed in all examples.

[0159] The video decoder 300 can store reconstructed blocks in the DPB 314. For example, in an example where the operation of the filter unit 312 is not performed, the reconstruction unit 310 can store the reconstructed blocks in the DPB 314. In an example where the operation of the filter unit 312 is performed, the filter unit 312 can store the filtered reconstructed blocks in the DPB 314. As discussed above, the DPB 314 can provide reference information (such as samples of the current image for intra-frame prediction and samples of previously decoded images for subsequent motion compensation) to the prediction processing unit 304. Furthermore, the video decoder 300 can output decoded images (e.g., decoded video) from the DPB 314 for use in applications such as... Figure 1 The subsequent presentation on display devices such as display device 118.

[0160] In this manner, video decoder 300 represents an example of a video decoding device, which includes: a memory configured to store video data; and one or more processing units implemented in a circuit and configured to: determine a minimum sample value of one or more blocks of the video data, the minimum sample value being greater than 0; and, in response to a process of determining a block applied to the one or more blocks of the video data resulting in a sample value less than the minimum sample value, crop a sample value to the minimum sample value. The one or more processing units implemented in the circuit may alternatively or additionally be configured to: determine a maximum sample value of one or more blocks of the video data, the maximum sample value being less than 2^bd - 1; and, in response to a process of determining a block applied to the one or more blocks of the video data resulting in a sample value greater than the maximum sample value, crop a sample value to the maximum sample value.

[0161] Figure 5 This is a flowchart illustrating an example process for encoding the current block according to the technology of this disclosure. The current block may be or may include the current CU. Although relative to the video encoder 200 ( Figure 1 and Figure 3 The description is provided, but it should be understood that other devices can be configured to perform the same actions. Figure 5 The process is similar to that of [the other process].

[0162] In this example, the video encoder 200 initially predicts the current block (400). For example, the video encoder 200 may form a prediction block for the current block. The video encoder 200 may then compute a residual block for the current block (402). To compute the residual block, the video encoder 200 may compute the difference between the unencoded original block for the current block and the prediction block. The video encoder 200 may then transform the residual block and quantize the transform coefficients of the residual block (404). Next, the video encoder 200 may scan the quantized transform coefficients of the residual block (406). During or after the scan, the video encoder 200 may entropy encode the transform coefficients (408). For example, the video encoder 200 may use CAVLC or CABAC to encode the transform coefficients. The video encoder 200 may then output the entropy-encoded data of the block (410).

[0163] Figure 6 This is a flowchart illustrating an example process for decoding a current block of video data according to the technology of this disclosure. The current block may be or may include the current CU. Although relative to the video decoder 300 ( Figure 1 and Figure 4 The description is provided, but it should be understood that other devices can be configured to perform the same actions. Figure 6 The process is similar to that of [the other process].

[0164] The video decoder 300 may receive entropy-coded data for the current block, such as entropy-coded prediction information and entropy-coded data for the transform coefficients of the residual block corresponding to the current block (500). The video decoder 300 may entropy decode the entropy-coded data to determine prediction information for the current block and reproduce the transform coefficients of the residual block (502). The video decoder 300 may predict the current block, for example, using an intra-frame prediction mode or inter-frame prediction mode indicated by the prediction information of the current block (504), to compute a prediction block for the current block. The video decoder 300 may then inverse scan the reproduced transform coefficients (506) to create a block of quantized transform coefficients. The video decoder 300 may then inverse quantize the transform coefficients and apply the inverse transform to the transform coefficients to produce a residual block (508). The video decoder 300 may finally decode the current block by combining the prediction block and the residual block (510).

[0165] Figure 7 This is a flowchart illustrating an example process for decoding a current block of video data according to the technology of this disclosure. The current block may be or may include the current CU. Although relative to the video decoder 300 ( Figure 1 and Figure 7 The description is provided, but it should be understood that other devices can be configured to perform the same actions. Figure 7 The process is similar. For example, the video decoding loop of the video encoder 200 can also perform... Figure 7 The technology.

[0166] exist Figure 7 In the example, video decoder 300 determines a minimum sample value for one or more blocks of video data, the minimum sample value being greater than zero (520). To determine the minimum sample value, video decoder 300 may, for example, receive a first syntax element indicating the minimum sample value. The first syntax may include a quantized minimum sample value, and video decoder 300 may determine the minimum sample value based on the quantized minimum sample value, for example, by dequantizing the quantized minimum sample value.

[0167] Video decoder 300 determines a maximum sample value less than 2^bd - 1 for one or more blocks of video data, where bd represents the bit depth (522) of the samples in the one or more blocks of video data. To determine the maximum sample value, video decoder 300 may, for example, receive a second syntax element indicating the maximum sample value. The second syntax may include a quantized maximum sample value, and video decoder 300 can determine the maximum sample value based on the quantized maximum sample value, for example, by dequantizing the quantized maximum sample value.

[0168] In response to the process of determining a block within one or more blocks of video data resulting in sample values ​​outside the range of minimum to maximum sample values, the video decoder 300 trims the sample values ​​to either the minimum or maximum sample values ​​(524). The sample values ​​can be, for example, luminance or chrominance sample values. The process of applying to a block can, for example, include adding predicted samples of the block to the residual samples of the block to determine reconstructed samples of the block, and sample values ​​outside the range of minimum to maximum sample values ​​can be values ​​of one reconstructed sample within the reconstructed samples. In other examples, the process of applying to a block can be an ALF process for determining filtered samples, and sample values ​​outside the range of minimum to maximum sample values ​​can be values ​​of one filtered sample within the filtered samples.

[0169] The video decoder 300 determines the decoded version of a block based on the cropped sample values ​​(526). The video decoder 300 outputs an image (528) containing the decoded version of the block of video data. The video decoder 300 may, for example, output the decoded image for display, transmission, or storage. Figure 7 When the process is performed as part of the video encoding process, the decoded images can be stored for use when encoding other images of the video data.

[0170] The following numbered clauses illustrate one or more aspects of the devices and technologies described in this disclosure.

[0171] Clause 1A: A method for decoding video data, the method comprising: determining a minimum sample value for one or more blocks of video data, wherein the minimum sample value is greater than 0; determining a maximum sample value for the one or more blocks of video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; and, in response to a process of determining a block applied to the one or more blocks of video data resulting in a sample value outside the range of the minimum sample value to the maximum sample value, cropping the sample value to either the minimum sample value or the maximum sample value.

[0172] Clause 2A: The method described in Clause 1A, wherein the process includes one of filtering, weighted prediction, weighted combination, mixing, or reconstruction.

[0173] Clause 3A: The method according to Clause 1A or 2A, wherein determining the minimum sample value includes: receiving a first syntax element in the image header that indicates the minimum sample value.

[0174] Clause 4A: The method according to any one of Clauses 1A to 3A, wherein determining the maximum sample value comprises: receiving a second syntax element in the image header indicating the maximum sample value.

[0175] Clause 5A: The method according to Clause 1A or 2A, wherein determining the minimum sample value includes: determining the minimum sample value based on the sample values ​​of the images in the image buffer.

[0176] Clause 6A: The method according to Clause 1A or 2A, wherein determining the maximum sample value includes: determining the maximum sample value based on the sample values ​​of the images in the image buffer.

[0177] Clause 7A: The method according to any one of Clauses 1A to 6A, wherein determining the minimum sample value comprises: determining a quantized minimum sample value, and determining the minimum sample value based on the quantized minimum sample value.

[0178] Clause 8A: The method according to any one of Clauses 1A to 7A, wherein determining the maximum sample value comprises: determining the quantized maximum sample value, and determining the maximum sample value based on the quantized maximum sample value.

[0179] Clause 9A: The method according to any one of Clauses 1A to 8A, wherein the sample values ​​include luminance sample values.

[0180] Clause 10A: The method according to any one of Clauses 1A to 8A, wherein the sample values ​​include chromaticity sample values.

[0181] Clause 11A: A method for decoding video data, the method comprising: determining a minimum sample value for one or more blocks of video data, wherein the minimum sample value is greater than 0; and, in response to a process of determining a block applied to the one or more blocks of video data resulting in a sample value less than the minimum sample value, cropping the sample value to the minimum sample value.

[0182] Clause 12A: A method for decoding video data, the method comprising: determining a maximum sample value for one or more blocks of video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; and cropping the sample value to the maximum sample value in response to a process of determining a sample value greater than the maximum sample value resulting from a process of applying the process to a block in the one or more blocks of video data.

[0183] Clause 13A: The method described in accordance with Clause 11A or 12A further includes any one of Clauses 2A to 8A.

[0184] Clause 14A: The method according to any one of Clauses 1A to 13A, wherein decoding includes decoding.

[0185] Clause 15A: The method according to any one of Clauses 1A, 2A or 5A to 13A, wherein decoding includes encoding.

[0186] Clause 16A: An apparatus for decoding video data, the apparatus comprising one or more components for performing the method according to any one of Clauses 1A to 15A.

[0187] Clause 17A: The device pursuant to Clause 16A, wherein the one or more components include one or more processors implemented in a circuit.

[0188] Clause 18A: The device according to any one of Clauses 16A and 17A further includes a memory for storing the video data.

[0189] Clause 19A: The device according to any one of Clauses 14A to 16A further includes a display configured to display decoded video data.

[0190] Clause 20A: A device pursuant to any one of Clauses 16A to 19A, wherein the device includes one or more of the following: a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0191] Clause 21A: A device pursuant to any one of Clauses 16A to 20A, wherein said device includes a video decoder.

[0192] Clause 22A: The device pursuant to any one of Clauses 16A to 21A, wherein the device includes a video encoder.

[0193] Clause 23A: A computer-readable storage medium having instructions stored thereon, which, when executed, cause one or more processors to perform the method according to any one of Clauses 1A to 15A.

[0194] Clause 1B: A method for decoding video data, the method comprising: determining a minimum sample value for one or more blocks of video data, wherein the minimum sample value is greater than 0; determining a maximum sample value for the one or more blocks of video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; in response to a process of determining a block applied to the one or more blocks of video data resulting in a sample value outside the range of the minimum sample value to the maximum sample value, cropping the sample value to either the minimum sample value or the maximum sample value to produce a cropped sample value; determining a decoded version of the block based on the cropped sample value; and outputting an image of decoded video data including the decoded version of the block.

[0195] Clause 2B: The method according to Clause 1B, wherein the process applied to the block comprises: adding a predicted sample of the block to a residual sample of the block to determine a reconstructed sample of the block, and wherein the sample value outside the range of the minimum sample value to the maximum sample value is a value of a reconstructed sample in the reconstructed sample.

[0196] Clause 3B: The method according to Clause 1B, wherein the process applied to the block includes an adaptive loop filtering process for determining filtered samples, and the sample values ​​outside the range from the minimum sample value to the maximum sample value are the values ​​of one filtered sample among the filtered samples.

[0197] Clause 4B: The method according to Clause 1B, wherein the process applied to the block includes one of the following: deblocking filtering, sample adaptive offset, downsampling, upsampling, reference image resampling (RPR) and scaling, cross-component prediction, weighted combination of different predictors, weighted prediction, prediction multiplied by a scaling factor, domain mapping, or weighted mixing at the edge.

[0198] Clause 5B: The method according to any one of Clauses 1B to 4B, wherein determining the minimum sample value comprises: receiving a first syntax element in the image header indicating the minimum sample value.

[0199] Clause 6B: The method according to any one of Clauses 1B to 5B, wherein determining the maximum sample value comprises: receiving a second syntax element in the image header indicating the maximum sample value.

[0200] Clause 7B: The method according to any one of Clauses 1B to 6B, wherein determining the maximum sample value comprises: determining the quantized maximum sample value, and determining the maximum sample value based on the quantized maximum sample value.

[0201] Clause 8B: The method according to any one of Clauses 1B to 7B, wherein the sample values ​​include luminance sample values.

[0202] Clause 9B: The method according to any one of Clauses 1B to 8B, wherein the sample values ​​include chromaticity sample values.

[0203] Clause 10B: The method according to any one of Clauses 1B to 4B, 8B or 9B, wherein the method of decoding video data is performed as part of a video encoding process.

[0204] Clause 11B: An apparatus for decoding video data, the apparatus comprising: a memory configured to store video data; one or more processors implemented in a circuit and configured to: determine a minimum sample value for one or more blocks of video data, wherein the minimum sample value is greater than 0; determine a maximum sample value for one or more blocks of video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; in response to a process of determining a block applied to the one or more blocks of video data resulting in a sample value outside the range of the minimum sample value to the maximum sample value, crop the sample value to either the minimum sample value or the maximum sample value to produce a cropped sample value; determine a decoded version of the block based on the cropped sample value; and output an image of decoded video data including the decoded version of the block.

[0205] Clause 12B: The apparatus according to Clause 11B, wherein the process applied to the block comprises: adding a predicted sample of the block to a residual sample of the block to determine a reconstructed sample of the block, and wherein the sample value outside the range of the minimum sample value to the maximum sample value is a value of a reconstructed sample in the reconstructed sample.

[0206] Clause 13B: The apparatus according to Clause 11B, wherein the process applied to the block includes an adaptive loop filtering process for determining filtered samples, and the sample values ​​outside the range from the minimum sample value to the maximum sample value are the values ​​of one filtered sample among the filtered samples.

[0207] Clause 14B: A device pursuant to Clause 11B wherein the process applied to the block includes one of the following: deblocking filtering, sample adaptive offset, downsampling, upsampling, reference image resampling (RPR) and scaling, cross-component prediction, weighted combination of different predictors, weighted prediction, prediction multiplied by a scaling factor, domain mapping, or weighted mixing at the edge.

[0208] Clause 15B: A device pursuant to any one of Clauses 11B to 14B, wherein, in order to determine the minimum sample value, the one or more processors are further configured to: receive a first syntax element in the image header indicating the minimum sample value.

[0209] Clause 16B: A device pursuant to any one of Clauses 11B to 15B, wherein, in order to determine the maximum sample value, the one or more processors are further configured to: receive a second syntax element in the image header indicating the maximum sample value.

[0210] Clause 17B: The device according to any one of Clauses 11B to 16B, wherein, in order to determine the maximum sample value, the one or more processors are further configured to: determine the quantized maximum sample value, and determine the maximum sample value based on the quantized maximum sample value.

[0211] Clause 18B: A device pursuant to any one of Clauses 11B to 17B, wherein the sample values ​​include luminance sample values.

[0212] Clause 19B: The device pursuant to any one of Clauses 11B to 18B, wherein the sample values ​​include chromaticity sample values.

[0213] Clause 20B: The device according to any one of Clauses 11B to 20B further includes a display device configured to display the picture of decoded video data.

[0214] Clause 21B: The device pursuant to any one of Clauses 11B to 20B, wherein the device includes one or more of the following: a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0215] Clause 22B: A method for encoding video data, the method comprising: determining a minimum sample value for one or more blocks of unencoded video data, wherein the minimum sample value is greater than 0; determining a maximum sample value for the one or more blocks of the unencoded video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; encoding the unencoded video data to determine encoded video data; during decoding of the encoded video data, determining that a process applied to a block of video data results in a sample value outside the range of the minimum sample value to the maximum sample value; in response to determining that the process applied to the block results in a sample value outside the range of the minimum sample value to the maximum sample value, cropping the sample value to either the minimum sample value or the maximum sample value to produce a cropped sample value; determining a decoded version of the block based on the cropped sample value; and storing an image of the decoded video data including the decoded version of the block in a decoded image buffer.

[0216] Clause 23B: The method according to Clause 22B, wherein the process applied to the block comprises: adding a predicted sample of the block to a residual sample of the block to determine a reconstructed sample of the block, and wherein the sample value outside the range of the minimum sample value to the maximum sample value is a value of a reconstructed sample in the reconstructed sample.

[0217] Clause 24B: The method according to Clause 22B, wherein the process applied to the block includes an adaptive loop filtering process for determining filtered samples, and the sample values ​​outside the range from the minimum sample value to the maximum sample value are the values ​​of one filtered sample among the filtered samples.

[0218] Clause 25B: The method according to Clause 22B, wherein the process applied to the block includes one of the following: deblocking filtering, sample adaptive offset, downsampling, upsampling, reference image resampling (RPR) and scaling, cross-component prediction, weighted combination of different predictors, weighted prediction, prediction multiplied by a scaling factor, domain mapping, or weighted mixing at the edge.

[0219] Clause 26B: The method according to any one of Clauses 22B to 25B, the method further comprising: transmitting encoded video data, the encoded video data including a first syntax element indicating the minimum sample value and a second syntax element indicating the maximum sample value.

[0220] Clause 27B: An apparatus for encoding video data, the apparatus comprising: a memory configured to store video data; one or more processors implemented in a circuit and configured to: determine a minimum sample value for one or more blocks of unencoded video data, wherein the minimum sample value is greater than 0; determine a maximum sample value for the one or more blocks of the unencoded video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of a sample in the one or more blocks of video data; encode the unencoded video data to determine encoded video data; when decoding the encoded video data, determining a block of video data resulting in a sample value outside the range of the minimum sample value to the maximum sample value; in response to determining the sample value outside the range of the minimum sample value to the maximum sample value resulting from the process of determining the block, cropping the sample value to either the minimum sample value or the maximum sample value to produce a cropped sample value; determining a decoded version of the block based on the cropped sample value; and storing an image of the decoded video data including the decoded version of the block in a decoded image buffer.

[0221] Clause 28B: The apparatus according to Clause 27B, wherein the process applied to the block comprises: adding a predicted sample of the block to a residual sample of the block to determine a reconstructed sample of the block, and wherein the sample value outside the range of the minimum sample value to the maximum sample value is a value of a reconstructed sample in the reconstructed sample.

[0222] Clause 29B: The apparatus according to Clause 27B, wherein the process applied to the block includes an adaptive loop filtering process for determining filtered samples, and the sample values ​​outside the range from the minimum sample value to the maximum sample value are the values ​​of one filtered sample among the filtered samples.

[0223] Clause 30B: A device pursuant to any one of Clauses 27B to 29B, wherein the one or more processors are further configured to: transmit encoded video data, the encoded video data including a first syntax element indicating the minimum sample value and a second syntax element indicating the maximum sample value.

[0224] It should be recognized that, based on the examples, certain actions or events of any technique described herein may be performed in a different sequence, and may be added, combined, or omitted entirely (e.g., not all actions or events described are necessary for implementing the technique). Furthermore, in some examples, actions or events may be performed concurrently (e.g., through multithreading, interrupt handling, or multiple processors) rather than sequentially.

[0225] In one or more examples, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functionality may be stored as one or more instructions or code on a computer-readable medium or transmitted via a computer-readable medium and executed by a hardware-based processing unit. A computer-readable medium may include a computer-readable storage medium (which corresponds to a tangible medium such as a data storage medium) or a communication medium, including, for example, any medium that facilitates the transfer of a computer program from one place to another according to a communication protocol. Thus, a computer-readable medium may generally correspond to (1) a non-transitory tangible computer-readable storage medium, or (2) a communication medium such as a signal or carrier wave. A data storage medium 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. Computer program products may include computer-readable media.

[0226] By way of example, and not limitation, such computer-readable storage media may include one or more of RAM, ROM, EEPROM, CD-ROM or other optical disc storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory, or any other medium capable of storing desired program code in the form of instructions or data structures and accessible by a computer. Furthermore, any connection is appropriately referred to as 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 technology (such as infrared, radio, and microwave), then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but instead refer to non-transient tangible storage media. As used herein, disks and optical discs include compact optical discs (CDs), laser optical discs, optical discs, digital versatile optical discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while optical discs use lasers to reproduce data optically. Combinations of these should also be included within the scope of computer-readable media.

[0227] Instructions can be executed by one or more processors, such as one or more DSPs, general-purpose microprocessors, ASICs, FPGAs, or other equivalent integrated or discrete logic circuits. Therefore, the terms "processor" and "processing circuit" as used herein can refer to any of the foregoing structures or any other structure suitable for implementing the techniques described herein. Additionally, in some aspects, the functionality described herein can be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into combined codecs. Furthermore, these techniques can be fully implemented in one or more circuit or logic elements.

[0228] The techniques disclosed herein can be implemented in a wide variety of devices or apparatuses, including wireless mobile phones, integrated circuits (ICs), or a set of ICs (e.g., chipsets). Various components, modules, or units are described in this disclosure to emphasize functional aspects of a device configured to perform the disclosed techniques, but implementation by different hardware units is not necessarily required. Specifically, as described above, various units may be combined in a codec hardware unit, or various units may be provided by a collection of interoperable hardware units (including one or more processors as described above) combined with appropriate software and / or firmware.

[0229] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. A method for decoding video data, the method comprising: Determine the minimum sample value of one or more blocks of video data, wherein the minimum sample value is greater than 0; Determine the maximum sample value of the one or more blocks of video data, wherein the maximum sample value is less than 2^bd -1, where bd is the bit depth of the sample in the one or more blocks of video data; In response to the process of determining a block among the one or more blocks applied to the video data, resulting in sample values ​​outside the range of the minimum sample value to the maximum sample value, the sample values ​​are cropped to one of the minimum sample value or the maximum sample value to produce cropped sample values. The decoding version of the block is determined based on the cropped sample values; as well as The output includes an image of the decoded video data of the decoded version of the block.

2. The method of claim 1, wherein the process applied to the block comprises: The predicted samples of the block are added to the residual samples of the block to determine the reconstructed samples of the block, and wherein the sample values ​​outside the range of the minimum sample value to the maximum sample value are the values ​​of a reconstructed sample in the reconstructed samples.

3. The method of claim 1, wherein the process applied to the block includes an adaptive loop filtering process for determining filtered samples, and the sample value outside the range of the minimum sample value to the maximum sample value is the value of a filtered sample among the filtered samples.

4. The method of claim 1, wherein the process applied to the block comprises one of the following: deblocking filtering, sample adaptive offset, downsampling, upsampling, reference image resampling (RPR) and scaling, cross-component prediction, weighted combination of different prediction factors, weighted prediction, prediction multiplied by a scaling factor, domain mapping, or weighted mixing at the edge.

5. The method of claim 1, wherein determining the minimum sample value comprises: Receive the first syntax element in the image header that indicates the minimum sample value.

6. The method of claim 1, wherein determining the maximum sample value comprises: Receive the second syntax element in the image header that indicates the maximum sample value.

7. The method of claim 1, wherein determining the maximum sample value comprises: Determine the maximum sample value after quantization, and determine the maximum sample value based on the maximum sample value after quantization.

8. The method according to claim 1, wherein the sample values ​​include luminance sample values.

9. The method of claim 1, wherein the sample values ​​include chromaticity sample values.

10. The method of claim 1, wherein the method for decoding video data is performed as part of a video encoding process.

11. An apparatus for decoding video data, the apparatus comprising: A memory configured to store video data; One or more processors, said one or more processors being implemented in a circuit and configured to: Determine the minimum sample value of one or more blocks of video data, wherein the minimum sample value is greater than 0; Determine the maximum sample value of one or more blocks of video data, wherein the maximum sample value is less than 2^bd -1, where bd is the bit depth of the sample in the one or more blocks of video data; In response to the process of determining a block among the one or more blocks applied to the video data, resulting in sample values ​​outside the range of the minimum sample value to the maximum sample value, the sample values ​​are cropped to one of the minimum sample value or the maximum sample value to produce cropped sample values. The decoding version of the block is determined based on the cropped sample values; as well as The output includes an image of the decoded video data of the decoded version of the block.

12. The device of claim 11, wherein the process applied to the block comprises: The predicted samples of the block are added to the residual samples of the block to determine the reconstructed samples of the block, and wherein the sample values ​​outside the range of the minimum sample value to the maximum sample value are the values ​​of a reconstructed sample in the reconstructed samples.

13. The apparatus of claim 11, wherein the process applied to the block includes an adaptive loop filtering process for determining filtered samples, and the sample values ​​outside the range from the minimum sample value to the maximum sample value are the values ​​of one filtered sample among the filtered samples.

14. The device of claim 11, wherein the process applied to the block comprises one of the following: deblocking filtering, sample adaptive offset, downsampling, upsampling, reference image resampling (RPR) and scaling, cross-component prediction, weighted combination of different prediction factors, weighted prediction, prediction multiplied by a scaling factor, domain mapping, or weighted mixing at the edge.

15. The device of claim 11, wherein, in order to determine the minimum sample value, the one or more processors are further configured to: receive a first syntax element in the image header indicating the minimum sample value.

16. The device of claim 11, wherein, in order to determine the maximum sample value, the one or more processors are further configured to: receive a second syntax element in the image header indicating the maximum sample value.

17. The device of claim 11, wherein, in order to determine the maximum sample value, the one or more processors are further configured to: determine a quantized maximum sample value, and determine the maximum sample value based on the quantized maximum sample value.

18. The device of claim 11, wherein the sample values ​​include luminance sample values.

19. The device of claim 11, wherein the sample values ​​include chromaticity sample values.

20. The apparatus of claim 11, further comprising a display device configured to display the image of decoded video data.

21. The device of claim 11, wherein the device comprises one or more of the following: a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

22. A method for encoding video data, the method comprising: Determine the minimum sample value of one or more blocks of uncoded video data, wherein the minimum sample value is greater than 0; Determine the maximum sample value of the one or more blocks of the uncoded video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of the sample in the one or more blocks of the video data; The unencoded video data is encoded to determine the encoded video data; When decoding the encoded video data, the process of determining the blocks applied to the video data results in sample values ​​outside the range of the minimum sample value to the maximum sample value; In response to determining that the process applied to the block results in a sample value outside the range of the minimum to the maximum sample value, the sample value is cropped to either the minimum or the maximum sample value to produce a cropped sample value. The decoding version of the block is determined based on the cropped sample values; as well as The image containing the decoded version of the video data, including the block, is stored in the decoded image buffer.

23. The method of claim 22, wherein the process applied to the block comprises: The predicted samples of the block are added to the residual samples of the block to determine the reconstructed samples of the block, and wherein the sample values ​​outside the range of the minimum sample value to the maximum sample value are the values ​​of a reconstructed sample in the reconstructed samples.

24. The method of claim 22, wherein the process applied to the block includes an adaptive loop filtering process for determining filtered samples, and the sample values ​​outside the range of the minimum to the maximum sample values ​​are the values ​​of one filtered sample among the filtered samples.

25. The method of claim 22, wherein the process applied to the block comprises one of: deblocking filtering, sample adaptive offset, downsampling, upsampling, reference image resampling (RPR) and scaling, cross-component prediction, weighted combination of different predictors, weighted prediction, prediction multiplied by a scaling factor, domain mapping, or weighted mixing at the edge.

26. The method according to claim 22, further comprising: Transmit encoded video data, the encoded video data including a first syntax element indicating the minimum sample value and a second syntax element indicating the maximum sample value.

27. An apparatus for encoding video data, the apparatus comprising: A memory configured to store video data; One or more processors, said one or more processors being implemented in a circuit and configured to: Determine the minimum sample value of one or more blocks of uncoded video data, wherein the minimum sample value is greater than 0; Determine the maximum sample value of the one or more blocks of the uncoded video data, wherein the maximum sample value is less than 2^bd - 1, where bd is the bit depth of the sample in the one or more blocks of the video data; The unencoded video data is encoded to determine the encoded video data; When decoding the encoded video data, the process of determining the blocks applied to the video data results in sample values ​​outside the range of the minimum sample value to the maximum sample value; In response to determining that the process applied to the block results in a sample value outside the range of the minimum to the maximum sample value, the sample value is cropped to either the minimum or the maximum sample value to produce a cropped sample value. The decoding version of the block is determined based on the cropped sample values; as well as The image containing the decoded version of the video data, including the block, is stored in the decoded image buffer.

28. The apparatus of claim 27, wherein the process applied to the block comprises: The predicted samples of the block are added to the residual samples of the block to determine the reconstructed samples of the block, and wherein the sample values ​​outside the range of the minimum sample value to the maximum sample value are the values ​​of a reconstructed sample in the reconstructed samples.

29. The apparatus of claim 27, wherein the process applied to the block includes an adaptive loop filtering process for determining filtered samples, and the sample values ​​outside the range from the minimum sample value to the maximum sample value are the values ​​of one filtered sample among the filtered samples.

30. The apparatus of claim 27, wherein the one or more processors are further configured to: transmit encoded video data, the encoded video data including a first syntax element indicating the minimum sample value and a second syntax element indicating the maximum sample value.

Images