Deriving Rice parameters for coding high bit depth video data - Patents.com

Abstract

An exemplary device for coding video data includes a memory configured to store the video data and one or more processors implemented in a circuit, where the one or more processors are configured to: calculate a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculate a base level offset value according to a bit depth for the video data and a slice type for a slice that includes the current block; calculate a normalized value for the sum of absolute values ​​using the base level offset value; and code the current coefficient using the normalized value for the sum of absolute values.

Description

Priority claims

[0001]

[0001] This application claims priority to U.S. Patent Application No. 17 / 658,396, filed April 7, 2022, and U.S. Provisional Application No. 63 / 173,269, filed April 9, 2021, the entire contents of each of which are incorporated herein by reference. U.S. Application No. 17 / 658,396, filed April 7, 2022, claims the benefit of U.S. Provisional Application No. 63 / 173,269, filed April 9, 2021. [Technical Field]

[0002] This disclosure relates to video coding, including video encoding and video decoding. [Background technology]

[0003] Digital video capabilities may be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video gaming devices, video game consoles, cellular or satellite radiotelephones, so-called "smartphones," video teleconferencing devices, video streaming devices, etc. Digital video devices implement video coding techniques such as those described in standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264 / MPEG-4, Part 10, Advanced Video Coding (AVC), ITU-T H.265 / High Efficiency Video Coding (HEVC), ITU-T H.266 / Versatile Video Coding (VVC), and extensions to such standards, as well as proprietary video codecs / formats such as AOMedia Video1 (AV1) developed by the Alliance for Open Media. By implementing such video coding techniques, video devices may more efficiently transmit, receive, encode, decode, and / or store digital video information.

[0004]

[0004] Video coding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences. In block-based video coding, video slices (e.g., video pictures or portions of video pictures) may be partitioned into video blocks, which may also be referred to as coding tree units (CTUs), coding units (CUs), and / or coding nodes. Video blocks in intra-coded (I) slices of a picture are encoded using spatial prediction with respect to reference samples in neighboring blocks in the same picture. Video blocks in inter-coded (P or B) slices of a picture may use spatial prediction with respect to reference samples in neighboring blocks in the same picture or temporal prediction with respect 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] Generally, this disclosure describes techniques for deriving Rice parameters for coding video data, e.g., high-bit-depth video data. In particular, the Rice parameters may be used when performing regular residual coding (RRC), which may include encoding and / or decoding. These techniques may be applied in ITU-T H.266 / generalized video coding (VVC) or other video coding standards. The techniques of this disclosure are generally directed to determining a Rice parameter to be used to binarize a current coefficient of a transform block of video data, where determining the Rice parameter includes using a base-level offset value. The base-level offset value may be calculated according to at least one of a bit depth for the video data or a slice type for a slice of the video data. The base-level offset value may then be applied to a sum of absolute values ​​for coefficients neighboring the current coefficient to calculate a normalized value. The normalized value may be used to determine the Rice parameter, e.g., from a lookup table. The Rice parameter may then be used to binarize a value for the current coefficient.

[0006]

[0006] In one example, a method for coding (encoding and / or decoding) video data includes calculating a sum of absolute values ​​of multiple adjacent coefficients relative to a current coefficient for a current block of the video data, calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block, calculating a normalized value for the sum of absolute values ​​using the base level offset value, and coding the current coefficient using the normalized value for the sum of absolute values.

[0007]

[0007] In another example, a device for coding (encoding and / or decoding) video data includes a memory configured to store the video data and one or more processors implemented in the circuit, wherein the one or more processors are configured to: calculate a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculate a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculate a normalized value for the sum of absolute values ​​using the base level offset value; and code the current coefficient using the normalized value for the sum of absolute values.

[0008]

[0008] In another example, a computer-readable storage medium stores instructions that, when executed, cause a processor of a device for coding video data to calculate a sum of absolute values ​​of multiple adjacent coefficients relative to a current coefficient for a current block of video data, calculate a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block, calculate a normalized value for the sum of absolute values ​​using the base level offset value, and code the current coefficient using the normalized value for the sum of absolute values.

[0009]

[0009] In another example, a device for coding (encoding and / or decoding) video data includes means for calculating a sum of absolute values ​​of multiple adjacent coefficients relative to a current coefficient for a current block of the video data, means for calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block, means for calculating a normalized value for the sum of absolute values ​​using the base level offset value, and means for coding the current coefficient using the normalized value for the sum of absolute values.

[0010] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0011] [Figure 1]

[0011] FIG. 1 is a block diagram illustrating an example video encoding and decoding system in which the techniques of this disclosure may be implemented. [Figure 2]

[0012] 1 is a conceptual diagram illustrating an example of neighboring coefficients relative to a current coefficient that may be used to calculate local sums of absolute values ​​(locSumAbs). [Figure 3]

[0013] 10 is a graph showing an empirical histogram of coded transform coefficients for a 16-bit test sequence of video data. [Figure 4]

[0014] 10 is a graph illustrating the relationship between the codeword length produced during entropy coding of coefficient values ​​and a given Rice parameter. [Figure 5]

[0015] 1 is a block diagram illustrating an example video encoder that may implement the techniques of this disclosure. [Figure 6]

[0016] 1 is a block diagram illustrating an example video decoder that may implement the techniques of this disclosure. [Figure 7]

[0017] 10 is a flowchart illustrating an example method for encoding a current block, in accordance with techniques of this disclosure. [Figure 8]

[0018] 10 is a flowchart illustrating an example method for decoding a current block, in accordance with techniques of this disclosure. [Figure 9]

[0019] 1 is a flowchart illustrating an example method for encoding video data in accordance with techniques of this disclosure. [Figure 10]

[0020] 1 is a flowchart illustrating an example method for decoding video data in accordance with techniques of this disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0021] The Rice parameter value may be used to code (encode or decode) coefficients of a residual block of video data. In particular, the Rice parameter may be used when binarizing values ​​in connection with entropy coding (encoding or decoding) the values. The use of Rice parameter values ​​ranging from 0 to 3, inclusive, was extensively tested in the development of the ITU-T H.266 / Generic Video Coding (VVC) standard. Generally, the Rice parameter value is scaled using a clipping formula that also uses the bit depth of the corresponding video data as input. The clipping formula originally developed for VVC assumed a bit depth of 8 or 10 bits. However, if the bit depth is increased beyond 10 bits, the clipping function may no longer effectively clip the Rice parameter value to be within the 0 to 3 bit range, which may lead to a rapid increase in codeword size and, therefore, the value signaled in the bitstream. This disclosure describes techniques that may avoid such an increase in codeword size and data signaled in the bitstream when using Rice parameters to code video data using a high bit depth (e.g., a bit depth greater than 10 bits).

[0013]

[0022] A video coder (encoder or decoder) may be configured to use the techniques of this disclosure to code (encode or decode) a value for a current coefficient of a transform block. In particular, the video coder may first calculate a sum of absolute values ​​of neighboring coefficients relative to the current coefficient. The video coder may then calculate a base-level offset value to apply to the sum of absolute values ​​according to either or both of the bit depth for the video data and / or the slice type for the slice including the transform block. The video coder may then calculate a normalized value for the sum of absolute values ​​using the base-level offset value. The video coder may then code the current coefficient using the normalized value. As mentioned above, the techniques of this disclosure may be applied in contexts where the bit depth can extend beyond 10 bits. Thus, calculating the base-level offset value according to the bit depth may allow the Rice parameter to be clipped to remain within 0 to 3 bits.

[0014]

[0023] Video coding standards include ITU-T H.261, ISO / IEC MPEG-1 Visual, ITU-T H.262 or ISO / IEC MPEG-2 Visual, ITU-T H.263, ISO / IEC MPEG-4 Visual, and ITU-T H.264 (also known as ISO / IEC MPEG-4 AVC) including its Scalable Video Coding (SVC) and Multiview Video Coding (MVC) extensions. High Efficiency Video Coding (HEVC) was finalized by the Joint Collaboration Team on Video Coding (JCT-VC) between the ITU-T Video Coding Experts Group (VCEG) and the ISO / IEC Motion Picture Experts Group (MPEG) in April 2013.

[0015]

[0024] The Joint Video Experts Team (JVET), a collaborative team formed by MPEG and ITU-T Study Group 16's VCEG, continues to develop video coding techniques for and beyond the Generalized Video Coding (VVC) standard. The primary goal of VVC is to provide significant improvements in compression performance over the existing HEVC standard, aiding in the deployment of higher quality video services and emerging applications, such as 360° omnidirectional immersive multimedia and high dynamic range (HDR) video. A draft of the VVC standard can be found in Benjamin Bross, Jianle Chen, Shan Liu, and Ye-Kui Wang, "Versatile Video Coding (Draft 10)," Joint Video Experts Team (JVET) of ITU-T SG16 WP3 and ISO / IEC JTC1 / SC29 / WG11, Doc. JVET-S2001, 19th Meeting: Teleconference, June 22-July 1, 2020, available at phenix.it-sudparis.eu / jvet / doc_end_user / documents / 19_Teleconference / wg11 / JVET-S2001-v17.zip.

[0016]

[0025] 1 is a block diagram illustrating an example video encoding and decoding system 100 that may implement techniques of this disclosure. The techniques of this disclosure are generally directed to coding (encoding and / or decoding) video data. Generally, the video data includes some data for processing the video. Thus, the video data may include raw uncoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata, such as signaling data.

[0017]

[0026] 1, system 100 includes a source device 102 that, in this example, provides encoded video data to be decoded and displayed by a destination device 116. In particular, source device 102 provides the video data to destination device 116 via a computer-readable medium 110. Source device 102 and destination device 116 may comprise any of a wide range of devices, including desktop computers, notebook (i.e., laptop) computers, mobile devices, tablet computers, set-top boxes, telephone handsets such as smartphones, televisions, cameras, display devices, digital media players, video gaming consoles, video streaming devices, broadcast receiver devices, etc. In some cases, source device 102 and destination device 116 may be equipped for wireless communication and therefore may be referred to as wireless communication devices.

[0018]

[0027] In the example of FIG. 1 , source device 102 includes a video source 104, memory 106, a video encoder 200, and an output interface 108. Destination device 116 includes an input interface 122, a video decoder 300, memory 120, and a display device 118. According to this disclosure, video encoder 200 of source device 102 and video decoder 300 of destination device 116 may be configured to apply techniques for coding high bit-depth video data using Rice parameters. Thus, source device 102 represents an example of a video encoding device, and 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.

[0019]

[0028] The system 100 shown in FIG. 1 is merely an example. In general, any digital video encoding and / or decoding device may implement techniques for coding high bit-depth video data using Rice parameters. Source device 102 and destination device 116 are merely examples of coding devices, such that source device 102 generates coded video data for transmission to destination device 116. This disclosure refers to a “coding” device as a device that performs coding (encoding and / or decoding) of data. Accordingly, video encoder 200 and video decoder 300 represent examples of coding devices, particularly video encoders and video decoders, respectively. In some examples, source device 102 and destination device 116 may operate substantially symmetrically, such that each of source device 102 and destination device 116 includes video encoding and video decoding components. Thus, system 100 may support one-way or two-way video transmission between source device 102 and destination device 116, e.g., for video streaming, video playback, video broadcasting, or video telephony.

[0020]

[0029] Generally, video source 104 represents a source of video data (i.e., raw, uncoded video data) and provides a continuous series of pictures (also called “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 a video capture device, such as a video camera, a video archive containing previously captured live video, and / or a video feed interface for receiving video from a video content provider. As a further alternative, video source 104 may generate computer-graphics-based data as source video, or a combination of live, archived, and computer-generated video. In each case, video encoder 200 encodes the captured, pre-captured, or computer-generated video data. Video encoder 200 may reorder the pictures from their received order (sometimes referred to as “display order”) into a coding order for coding. Video encoder 200 may generate a bitstream including the encoded video data. Source device 102 may then output the encoded video data onto computer-readable medium 110 via output interface 108 for receipt and / or retrieval by, for example, input interface 122 of destination device 116.

[0021]

[0030] Memory 106 of source device 102 and memory 120 of destination device 116 represent general-purpose memory. In some examples, memory 106, 120 may store raw video data, e.g., raw video from video source 104 and raw decoded video data from video decoder 300. Additionally or alternatively, memory 106, 120 may store software instructions executable by video encoder 200 and video decoder 300, respectively, for example. While memory 106 and memory 120 are shown separate 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. Additionally, memory 106, 120 may store encoded video data, e.g., output from video encoder 200 and input to video decoder 300. In some examples, portions of the memory 106, 120 may be allocated as one or more video buffers, for example, to store raw decoded and / or encoded video data.

[0022]

[0031] The computer-readable medium 110 may represent any type of medium or device capable of transporting encoded video data from the source device 102 to the destination device 116. In one example, the computer-readable medium 110 represents a communication medium for enabling the source device 102 to transmit the encoded video data directly to the destination device 116 in real time, for example, via a radio frequency network or a computer-based network. The output interface 108 may modulate a transmission signal including the encoded video data, and the input interface 122 may demodulate a received transmission signal in accordance with a communication standard such as a wireless communication protocol. The communication medium may comprise any wireless or wired communication medium, such as a 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 routers, switches, base stations, or any other equipment that may be useful for facilitating communication from the source device 102 to the destination device 116.

[0023]

[0032] In some examples, source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access the encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media, such as a hard drive, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0024]

[0033] In some examples, source device 102 may output the encoded video data to file server 114 or another intermediate storage device, which may store the encoded video data generated by source device 102. Destination device 116 may access the stored video data from file server 114 via streaming or download.

[0025]

[0034] The file server 114 may be any type of server device capable of storing encoded video data and transmitting the encoded video data to the destination device 116. The file server 114 may represent a web server (e.g., for a website), a server configured to provide file transfer protocol services (e.g., File Transfer Protocol (FTP) or File Delivery over Unidirectional Transport (FLUTE) 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. The file server 114 may additionally or alternatively implement one or more HTTP streaming protocols, such as Dynamic Adaptive Streaming over HTTP (DASH), HTTP Live Streaming (HLS), Real Time Streaming Protocol (RTSP), HTTP Dynamic Streaming, etc.

[0026]

[0035] Destination device 116 may access the encoded video data from file server 114 through any standard data connection, including an Internet connection. This may include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., a digital subscriber line (DSL), a cable modem, etc.), or a combination of both, that is suitable for accessing the encoded video data stored on file server 114. Input interface 122 may be configured to operate according to any one or more of the various protocols described above for retrieving or receiving media data from file server 114, or other such protocols for retrieving media data.

[0027]

[0036] Output interface 108 and input interface 122 may 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 in which output interface 108 and input interface 122 comprise wireless components, output interface 108 and input interface 122 may be configured to transfer data, such as encoded video data, according to a cellular communication standard, such as 4G, 4G-LTE (Long Term Evolution), LTE-Advanced, 5G, etc. In some examples in which output interface 108 comprises a wireless transmitter, output interface 108 and input interface 122 may be configured to transfer data, such as encoded video data, according to other wireless standards, such as the IEEE 802.11 specification, the IEEE 802.15 specification (e.g., ZigBee), the Bluetooth standard, etc. In some examples, source device 102 and / or destination device 116 may include respective system-on-chip (SoC) devices. For example, the source device 102 may include an SoC device for performing functions attributed to the video encoder 200 and / or the output interface 108, and the destination device 116 may include an SoC device for performing functions attributed to the video decoder 300 and / or the input interface 122.

[0028]

[0037] The techniques of this disclosure may be applied to video coding supporting any of a variety of multimedia applications, such as over-the-air television broadcast, cable television transmission, satellite television transmission, Internet streaming video transmission such as Dynamic Adaptive Streaming over HTTP (DASH), digital video encoded on a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

[0029]

[0038] The input interface 122 of the destination device 116 receives the encoded video bitstream from the computer-readable medium 110 (e.g., a communication medium, a storage device 112, a file server 114, etc.). The encoded video bitstream may include signaling information defined by the video encoder 200 that is also used by the video decoder 300, such as syntax elements having values ​​that describe characteristics and / or processing of video blocks or other coded units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays decoded pictures of the decoded video data to a 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.

[0030]

[0039] Although not shown in FIG. 1, in some examples, the video encoder 200 and the video decoder 300 may each be integrated with an audio encoder and / or an audio decoder and may include appropriate MUX-DEMUX units or other hardware and / or software to handle multiplexed streams that include both audio and video in a common data stream.

[0031]

[0040] The video encoder 200 and the video decoder 300 may each be implemented as any of a variety of suitable encoder and / or decoder circuits, or any combination thereof, 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, etc. When the techniques are implemented partially in software, a device may store instructions for the software on a suitable non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to implement the techniques of this disclosure. Each of the video encoder 200 and the video decoder 300 may be included in one or more encoders or decoders, any 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 comprise integrated circuits, microprocessors, and / or wireless communication devices such as cellular phones.

[0032]

[0041] The video encoder 200 and the video decoder 300 may operate according to a video coding standard, such as ITU-T H.265, also known as High Efficiency Video Coding (HEVC), or extensions thereof, such as multiview and / or scalable video coding extensions. Alternatively, the video encoder 200 and the video decoder 300 may operate according to other proprietary or industry standards, such as ITU-T H.266, also known as Generic Video Coding (VVC). In other examples, the video encoder 200 and the video decoder 300 may operate according to proprietary video codecs / formats, such as AOMedia Video1 (AV1), extensions of AVI, and / or successor versions of AV1 (e.g., AV2). In other examples, the video encoder 200 and the video decoder 300 may operate according to other proprietary formats or industry standards. However, the techniques of this disclosure are not limited to any particular coding standard or format. In general, video encoder 200 and video decoder 300 may be configured to implement the techniques of this disclosure with any video coding technique that codes high bit-depth video data using Rice parameters.

[0033]

[0042] Generally, the video encoder 200 and the video decoder 300 may perform block-based coding of pictures. The term “block” generally refers to a structure containing data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and / or decoding process). For example, a block may include a two-dimensional matrix of luminance and / or chrominance data samples. Generally, the video encoder 200 and the video decoder 300 may code video data represented in YUV (e.g., Y, Cb, Cr) format. That is, rather than coding red, green, and blue (RGB) data for a picture sample, the video encoder 200 and the video decoder 300 may code a luminance component and a chrominance component, where the chrominance component may include both red and blue hues of chrominance components. In some examples, the video encoder 200 converts received RGB-formatted data to a YUV representation prior to encoding, and the video decoder 300 converts the YUV representation to an RGB format. Alternatively, pre-processing and post-processing units (not shown) may perform these conversions.

[0034]

[0043] This disclosure may generally refer to coding (e.g., encoding and decoding) a picture to include the process of encoding or decoding data for a picture. Similarly, this disclosure may refer to coding a block of a picture to include the process of encoding or decoding data for the block, e.g., predictive and / or residual coding. A coded video bitstream generally includes a series of values ​​for syntax elements that represent coding decisions (e.g., coding modes) and the partitioning of a picture into blocks. Thus, references to coding a picture or a block should generally be understood as coding values ​​for the syntax elements that form the picture or block.

[0035]

[0044] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video coder (such as video encoder 200) partitions coding tree units (CTUs) into CUs according to a quadtree structure. That is, the video coder partitions CTUs and CUs into four equal, non-overlapping squares, and each node of the quadtree has either zero or four child nodes. A node without child nodes may be referred to as a "leaf node," and a CU of such a leaf node may include one or more PUs and / or one or more TUs. The video coder may further partition PUs and TUs. For example, in HEVC, a residual quadtree (RQT) represents the partitioning of TUs. In HEVC, a PU represents inter-predicted data, and a TU represents residual data. An intra-predicted CU includes intra-prediction information, such as an intra-mode indication.

[0036]

[0045] As another example, video encoder 200 and video decoder 300 may be configured to operate according to VVC. According to VVC, a video coder (such as video encoder 200) partitions a picture into multiple coding tree units (CTUs). Video encoder 200 may partition the CTUs according to a tree structure, such as a quad-tree binary tree (QTBT) structure or a multi-type tree (MTT) structure. The QTBT structure eliminates 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 quad-tree partitioning and a second level partitioned according to binary tree partitioning. The root node of the QTBT structure corresponds to a CTU. The leaf nodes of the binary tree correspond to coding units (CUs).

[0037]

[0046] In the MTT partitioning structure, blocks may be partitioned using quad tree (QT) partitioning, binary tree (BT) partitioning, and one or more types of triple tree (TT) (also called ternary tree (TT)) partitioning. Triple tree or ternary tree partitioning is a partitioning in which a block is split into three sub-blocks. In some examples, triple tree or ternary tree partitioning divides a block into three sub-blocks without splitting the original block through the center. The partitioning types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0038]

[0047] When operating according to the AV1 codec, video encoder 200 and video decoder 300 may be configured to code video data in blocks. In AV1, the largest coding block that can be processed is called a superblock. In AV1, a superblock can be either 128x128 luma samples or 64x64 luma samples. However, in successor video coding formats (e.g., AV2), a superblock may be defined by a different (e.g., larger) luma sample size. In some examples, a superblock is the top level of a block quadtree. Video encoder 200 may further partition the superblock into smaller coding blocks. Video encoder 200 may partition the superblock and other coding blocks into smaller blocks using square or non-square partitioning. Non-square blocks may include N / 2xN, NxN / 2, N / 4xN, and NxN / 4 blocks. Video encoder 200 and video decoder 300 may perform separate prediction and transform processes for each of the coding blocks.

[0039]

[0048] AV1 also defines tiles of video data. A tile is a rectangular array of superblocks that can be coded independently of other tiles. That is, video encoder 200 and video decoder 300 may encode and decode coding blocks within a tile, respectively, without using video data from other tiles. However, video encoder 200 and video decoder 300 may perform filtering across tile boundaries. Tiles may be uniform or non-uniform in size. Tile-based coding may enable parallel processing and / or multithreading for encoder and decoder implementations.

[0040]

[0049] 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 luminance and chrominance components, and 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 luminance component and another QTBT / MTT structure for both chrominance components (or two QTBT / MTT structures for each chrominance component).

[0041]

[0050] Video encoder 200 and video decoder 300 may be configured to use quadtree partitioning, QTBT partitioning, MTT partitioning, superblock partitioning, or other partitioning structures.

[0042]

[0051] In some examples, a CTU includes a coding tree block (CTB) of luma samples and two corresponding CTBs of chroma samples for a picture with three sample arrays, or a CTB for a monochrome picture or a picture coded using three separate color planes and syntax structures used to code the samples. The CTB may be an N×N block of samples, for some value of N such that the division of the components into the CTB is partitioned. A component may be an array or a single sample from one of three arrays (luma and two chroma) for a picture in 4:2:0, 4:2:2, or 4:4:4 color format, or an array or a single sample of an array for a picture in monochrome format. In some examples, a coding block is an M×N block of samples, for some value of M and N such that the division of the CTB into coding blocks is partitioned.

[0043]

[0052] Blocks (e.g., CTUs or CUs) may be grouped in various ways in a picture. As an example, a brick may refer to a rectangular region of a CTU row within a particular tile in a picture. A tile may be a rectangular region of a CTU within a particular tile column and a particular tile row in a picture. A tile column refers to a rectangular region of a CTU having a height equal to the height of the picture and a width specified by a syntax element (e.g., in a picture parameter set). A tile row refers to a rectangular region of a CTU having a height specified by a syntax element (e.g., in a picture parameter set) and a width equal to the width of the picture.

[0044]

[0053] In some examples, a tile may be partitioned into multiple bricks, each of which may contain one or more CTU rows within the tile. A tile that is not partitioned into multiple bricks may also be called a brick. However, a brick that is a true subset of a tile may not be called a tile. Bricks in a picture may also be arranged in slices. A slice may be an integer number of bricks of a picture that may be contained entirely in a single Network Abstraction Layer (NAL) unit. In some examples, a slice includes either several complete tiles or only a continuous sequence of complete bricks of one tile.

[0045]

[0054] This disclosure may use "N x N" and "N by N" interchangeably to refer to the sample dimensions of a block (such as a CU or other video block) in terms of the vertical and horizontal dimensions, e.g., 16 x 16 samples or 16 by 16 samples. Generally, a 16 x 16 CU has 16 samples in the vertical direction (y = 16) and 16 samples in the horizontal direction (x = 16). Similarly, an N x N CU generally 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 may be arranged in rows and columns. Moreover, a CU does not necessarily have to have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may comprise N x M samples, where M is not necessarily equal to N.

[0046]

[0055] Video encoder 200 encodes video data for a CU, which represents prediction and / or residual information and other information. The prediction information indicates how the CU should be predicted to form a predictive block for the CU. The residual information generally represents sample-by-sample differences between the samples of the CU prior to encoding and the predictive block.

[0047]

[0056] To predict a CU, the video encoder 200 may generally form a predictive block for the CU through inter-prediction or intra-prediction. Inter-prediction generally refers to predicting a CU from data of a previously coded picture, while intra-prediction generally refers to predicting a CU from previously coded data of the same picture. To perform inter-prediction, the video encoder 200 may generate a predictive block using one or more motion vectors. The video encoder 200 may generally perform motion search to identify a reference block that closely matches the CU, e.g., with respect to the difference between the CU and the reference block. The video encoder 200 may calculate a difference metric using a sum of absolute differences (SAD), a sum of squared differences (SSD), a mean absolute difference (MAD), a mean squared difference (MSD), or other such difference calculation to determine whether the reference block closely matches the current CU. In some examples, the video encoder 200 may predict the current CU using unidirectional prediction or bidirectional prediction.

[0048]

[0057] Some examples of VVC also provide an affine motion compensation mode, which may be considered an inter-prediction mode. In an affine motion compensation mode, video encoder 200 may determine two or more motion vectors that represent non-translational motion, such as zooming in or out, rotation, perspective motion, or other irregular motion types.

[0049]

[0058] To perform intra prediction, video encoder 200 may select an intra prediction mode to generate a predictive block. Some examples of VVC provide 67 intra prediction modes, including various directional modes as well as planar and DC modes. Generally, video encoder 200 selects an intra prediction mode that describes neighboring samples relative to a current block (e.g., a block of a CU) from which samples of the current block should be predicted. Such samples may generally be above, above-left, or to the left of the current block in the same picture as the current block, assuming that video encoder 200 codes CTUs and CUs in raster scan order (left to right, top to bottom).

[0050]

[0059] Video encoder 200 encodes data representing a prediction mode for the current block. For example, in an inter prediction mode, video encoder 200 may encode data representing which of various available inter prediction modes is used, as well as motion information for the corresponding mode. For example, in unidirectional or bidirectional inter prediction, video encoder 200 may encode motion vectors using advanced motion vector prediction (AMVP) or merge mode. Video encoder 200 may use similar modes to encode motion vectors for affine motion compensation modes.

[0051]

[0060] AV1 includes two general techniques for encoding and decoding coding blocks of video data. The two general techniques are intra-prediction (e.g., intra-frame prediction or spatial prediction) and inter-prediction (e.g., inter-frame prediction or temporal prediction). In the context of AV1, when predicting a block of a current frame of video data using an intra-prediction mode, the video encoder 200 and the video decoder 300 do not use video data from other frames of the video data. In most intra-prediction modes, the video encoder 200 encodes the block 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-prediction mode.

[0052]

[0061] Following prediction, such as intra-prediction or inter-prediction, of a block, the video encoder 200 may calculate residual data for the block. The residual data, such as a residual block, represents sample-by-sample differences between the block and a predictive block for the block formed using a corresponding prediction mode. The video encoder 200 may apply one or more transforms to the residual block to produce transformed data in a transform domain rather than the sample domain. For example, the video encoder 200 may apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. Furthermore, the video encoder 200 may apply a secondary transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, or a Karhunen-Loeve transform (KLT), following the first transform. The video encoder 200 produces transform coefficients following application of the one or more transforms.

[0053]

[0062] As described above, following any transformation to produce transform coefficients, the video encoder 200 may perform quantization of the transform coefficients. Quantization generally refers to a process in which transform coefficients are quantized to possibly reduce the amount of data used to represent the transform coefficients, 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 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 of the value to be quantized.

[0054]

[0063] Following quantization, the video encoder 200 may scan the transform coefficients to create a one-dimensional vector from a two-dimensional matrix including the quantized transform coefficients. The scan may be designed to place higher energy (and therefore lower frequency) transform coefficients at the front of the vector and lower energy (and therefore higher frequency) transform coefficients at the back of the vector. In some examples, the video encoder 200 may utilize a predefined scan order to scan the quantized transform coefficients to create a serialized vector and then entropy code the quantized transform coefficients of the vector. In other examples, the video encoder 200 may perform adaptive scanning. After scanning the quantized transform coefficients to form the one-dimensional vector, the video encoder 200 may entropy code the one-dimensional vector, for example, according to context-adaptive binary arithmetic coding (CABAC). The video encoder 200 may also entropy code values ​​for syntax elements describing metadata associated with the encoded video data for use by the video decoder 300 in decoding the video data.

[0055]

[0064] When encoding transform coefficients of a transform block, video encoder 200 may encode values ​​for syntax elements including, for example, a significant transform coefficient flag (indicating whether the coefficient has an absolute value greater than 0), a greater than one flag (indicating whether the coefficient has an absolute value greater than 1), a greater than two flag (indicating whether the coefficient has an absolute value greater than 2), a remainder value (representing the amount by which the absolute value of the coefficient exceeds 2), and a sign flag (representing whether the value for the coefficient is positive or negative).

[0056]

[0065] When encoding the residual value of the current coefficient, video encoder 200 may binarize the residual value using a Rice parameter. According to the techniques of this disclosure, to determine the Rice parameter, video encoder 200 may calculate a sum of absolute values ​​of neighboring coefficients relative to the current coefficient. For example, video encoder 200 may calculate absolute values ​​for the coefficient to the right, the coefficient two to the right, the coefficient below, the coefficient two below, and the coefficients below and to the right of the current coefficient, as shown in FIG. 2 below. Video encoder 200 may then add each of the calculated absolute values ​​to form a sum of absolute values ​​value. Video encoder 200 may then determine at least one of a bit depth and / or a slice type for the slice including the current block.

[0057]

[0066] Video encoder 200 may then calculate a base level offset value according to the bit depth and / or slice type, for example, using equation (1) described in more detail below. Video encoder 200 may then calculate a normalized value for the sum of absolute values ​​using the base level offset value. For example, video encoder 200 may calculate the normalized value using equation (2) described in more detail below. Video encoder 200 may then derive Rice parameters using the normalized values ​​for the local sum of absolute values, for example, according to Table 1 described in more detail below. Video encoder 200 may then form a Golomb-Rice code for the normalized value for the sum of absolute values ​​using the Rice parameters.

[0058]

[0067] To implement CABAC, video encoder 200 may assign a context in a context model to a symbol to be transmitted. The context may, for example, relate to whether neighboring values ​​of the symbol are zero values. A probability decision may be based on the context assigned to the symbol. For the transform coefficients described in the example above, the symbol may correspond to one of the bits (bins) of a Golomb-Rice code.

[0059]

[0068] Video encoder 200 may further generate syntax data, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, for video decoder 300, e.g., in a picture header, a block header, a slice header, or other syntax data, such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS). Video decoder 300 may similarly decode such syntax data to determine how to decode corresponding video data.

[0060]

[0069] In this manner, video encoder 200 may generate a bitstream including syntax elements that describe encoded video data, e.g., partitions of a picture into blocks (e.g., CUs) and prediction and / or residual information for the blocks. Finally, video decoder 300 may receive the bitstream and decode the encoded video data.

[0061]

[0070] Generally, video decoder 300 performs an inverse process to that performed by video encoder 200 to decode encoded video data of a bitstream. For example, video decoder 300 may decode values ​​for syntax elements of a bitstream using CABAC in a manner that is reverse to, but substantially similar to, the CABAC encoding process of video encoder 200. The syntax elements may define partition information for partitioning a picture into CTUs and the partitioning of each CTU according to a corresponding partition structure, such as a QTBT structure, to define CUs of the CTU. The syntax elements may further define prediction and residual information for blocks of video data (e.g., CUs).

[0062]

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

[0063]

[0072] According to the techniques of this disclosure, the video decoder 300 may receive an entropy-encoded value for a current coefficient of a transform block. The video decoder 300 may entropy decode the entropy-encoded value to form a Golomb-Rice code that represents the value of the current coefficient. The video decoder 300 may calculate a local sum of absolute values ​​of neighboring coefficients relative to the current coefficient. The video decoder 300 may also calculate a base-level offset value, for example, using equation (1) described below. The video decoder 300 may calculate a normalized value for the sum of absolute values ​​using the base-level offset value, for example, using equation (2) described below. The video decoder 300 may then determine a Rice parameter from the normalized value, for example, using Table 1 described below. The video decoder 300 may then binarize a value (e.g., an absolute residual value) for the current coefficient using the Rice parameter and from the Golomb-Rice code. The video decoder 300 may reconstruct the current coefficient from the absolute residual value and other decoded values ​​for the current coefficient, such as the sign value, the significant transform coefficient value, a value greater than one value, and a value greater than two value.

[0064]

[0073] This disclosure may generally refer to “signaling” certain information, such as syntax elements. The term “signaling” may generally refer to communication of values ​​for syntax elements and / or other data used to decode encoded video data. That is, video encoder 200 may signal values ​​for syntax elements in a bitstream. Generally, signaling refers to generating values ​​in a bitstream. As mentioned above, source device 102 may transport the bitstream to destination device 116 in substantially real time or may transport the bitstream to destination device 116 in non-real time, such as may be done when storing syntax elements to storage device 112 for later retrieval by destination device 116.

[0065]

[0074] Figure 2 is a conceptual diagram illustrating an example of coefficients neighboring a current coefficient that can be used to calculate the sum of local absolute values ​​(locSumAbs). In current designs of VVC, Rice parameters for residual coding (RRC) are typically derived using a lookup table with consideration of the coefficient values ​​of neighboring transform coefficients according to a template. The neighboring coefficients shaded gray in Figure 2 represent the template for the current coefficient shaded black in Figure 2.

[0066]

[0075] 2 illustrates a current block 130 that includes various transform coefficients. The current block 130 includes a current coefficient 132 and adjacent coefficients 134A-134E (neighboring coefficients 134). Relative to the location of the current coefficient 132, adjacent coefficient 134A represents the neighboring coefficient to the right, adjacent coefficient 134B represents the neighboring coefficient two to the right, adjacent coefficient 134C represents the neighboring coefficient to the lower right, adjacent coefficient 134D represents the neighboring coefficient below, and adjacent coefficient 134E represents the neighboring coefficient two below.

[0067]

[0076] The video coder may calculate a local sum of absolute values ​​(locSumAbs), for example, the sum of the absolute values ​​of neighboring coefficients 134 for the current coefficient 132. In accordance with VVC, the video coder calculates the value for locSumAbs as the sum of the absolute values ​​of the five available neighboring coefficients as in FIG. 2. In accordance with one example of VVC, the video coder then normalizes the value of locSumAbs (using subtraction and clipping) according to the following formula:

[0068]

number

[0069]

[0077] Then, according to VVC, the video coder uses the normalized values ​​of locSumAbs to derive the Rice parameters using Table 1 below.

[0070] [Table 1]

[0071]

[0078] In VVC, the Rice parameter range is constrained to be between 0 and 3, inclusive.

[0072]

[0079] According to the techniques of this disclosure, a video coder may calculate the base level offset according to equation (1), which will be described in more detail below. That is, the video coder may calculate the base level offset value according to the bit depth and / or slice type for the slice that includes current block 130.

[0073]

[0080] FIG. 3 is a graph illustrating an empirical histogram 136 of coded transform coefficients for a 16-bit test sequence of video data.

[0074]

[0081] FIG. 4 is a graph 140 illustrating the relationship between the codeword length produced during entropy coding of coefficient values ​​and a given Rice parameter.

[0075]

[0082] The Rice parameter has been extensively tested for encoding 8-bit or 10-bit depth video sources. In one exemplary design, the Rice parameter value depends on the value of the locSumAbs value and is limited to a range of 0 to 3 by clipping. When the bit depth of the input video is increased, or extended precision is enabled, or the quantization parameter is set very low, the range of coefficients, and therefore the locSumAbs value, may increase significantly. In such cases, the current VVC range of allowable Rice parameters is not sufficient because it would require the use of long codewords, e.g., 32-bit codewords, for large-valued coded coefficients.

[0076]

[0083] Figures 3 and 4 provide visualization of the resulting problems. In particular, Figure 3 shows a histogram of coded coefficients (in power-of-two form) for a 16-bit signal. Figure 4 shows the codeword lengths produced by the VVC entropy coding method for coded values. It can be seen from Figure 4 that limiting the canonical range of the Rice parameter to 3 (as defined in VVC) results in a significant increase in codeword length for coded values ​​greater than 10. This problem can be solved by allowing larger values ​​of the Rice parameter for coefficients of larger magnitude.

[0077]

[0084] In one design (CE1.1 of the JVET-U meeting) to address the limitations of the current VVC Rice parameter derivation at various input bit depths of video and thus improve compression efficiency, the supported range of the Rice parameter may be extended from 3 in VVC to a larger number, e.g., 16, which would provide a more efficient binarization process and result in lower bit counts for large values ​​of transform coefficients.

[0078]

[0085] The value of localSumbAbs may be scaled / normalized to handle bit depth increases or the dynamic range of the transform coefficients before being used to derive the Rice parameters, for example, according to equation 1517 of the VVC specification. The amount of the scaling factor may depend on the value localSumAbs - the output of a template derivation calculated to indicate the local activity of the transform coefficients, or on a syntax element or set of tabulated values ​​signaled in the bitstream.

[0079]

[0086] A VVC video encoder may compare the determined value of localSumAbs with a set of tabulated thresholds Tx={Tid} to identify the dynamic range id for the dynamic range that includes that value. The video coder may then scale and / or normalize the value of localSumAbs by the value scalar normShift from a given set of tabulated Rx={Rid} determined by the range id. The video coder may then use the normalized localSumAbs to derive Rice parameters using a predefined lookup table, e.g., the current lookup table in VVC, Table 128. Once the value of localSumbAbs is normalized in the first step of the proposed design, the Rice parameters may be derived from a predefined table, e.g., Table 128, and finally modified by adding an offset equal to Rid to extend the dynamic range of the Rice parameter range.

[0080]

[0087] The set of thresholds Tx and scalers Rx may be defined as follows:

[0081]

[0088]

[0082]

number

[0083]

[0089]

[0084]

number

[0085]

[0090] The values ​​of array Tx may be restricted to be powers of two, and in other embodiments, the values ​​may be derived by powers of two (2^x) and converted to such through a limited number of operations, such as offsetting, scaling, or right / left shifting.

[0086]

[0091] The size of the array may be equal to N, where N is a positive integer greater than a lower bound, e.g., >1 or >2, and less than an upper bound, e.g., 9 or 5. In some embodiments, the size of the Rx array is one entry larger than the Tx array. In some embodiments, the sizes of the Tx and Rx arrays may be limited to 4.

[0087]

[0092] In some examples, the relevant Rice parameter derivation part in VVC may be modified as follows, with the size of the tabulated array equal to 4: (See below for details within the box) 9.3.3.2 Rice Parameter Derivation Process for abs_remainder[] and dec_abs_level[] The inputs to this process are the base level baseLevel, the color component index cIdx, the luma location (x0, y0) specifying the top-left sample of the current transform block relative to the top-left sample of the current picture, the current coefficient scan location (xC, yC), the binary logarithm of the transform block width log2TbWidth, and the binary logarithm of the transform block height log2TbHeight. The output of this process is the rice parameter cRiceParam. Given an array AbsLevel[x][y] for a transform block with component index cIdx and top-left luma location (x0, y0), the variable locSumAbs is derived as specified by the following pseudocode process:

[0088]

number

[0089] g_riceT and g_riceShift are defined as follows:

[0090]

number

[0091] Given the variable locSumAbs, the rice parameter cRiceParam is derived as specified in Table 128. The cRiceParam is then refined as follows:

[0092]

number

[0093] (The above is within the box) To extend the range of the Rice parameter, CE1.2 of the U-Meeting proposes scaling the value locSumAbs by a shift if locSumAbs exceeds a certain threshold, so that the scaled value fits within the tolerance range of Table 128 of the VVC specification without clipping. Following this, the output of Table 128 is adjusted by incrementing by the shift value when the scaling process is performed for a given locSumAbs value.

[0094]

[0094] An encoder (eg, video encoder 200) may select a value for the syntax element sh_scale_rice, which may take the value 1 or 2.

[0095]

[0095]

[0096]

number

[0097]

[0096]

[0098]

number

[0099]

[0097] The value sh_scale_rice used is signaled as a syntax element in the slice header and is derived at the encoder side as a function of the QP value.

[0100]

[0098] The specification text for VVC may be as follows: sps_high_bit_depth equal to 1 specifies that the sh_rice_parameter syntax element may be present in the slice header to enable high bit-depth mode for Rice parameters for binarization of abs_remaining[] and dec_abs_level. sps_high_bit_depth equal to 0 specifies that the sh_rice_parameter syntax element is not present in the slice header and high bit-depth mode for Rice parameter derivation may not be enabled. When not present, the value of sps_high_bit_depth is inferred to be equal to 0. 7.3.7 Slice Header Syntax

[0101] [Table 2]

[0102] sh_scale_rice specifies the scale value used to derive the rice parameter, and the value of sh_scale_rice shall be in the range 1 to 2 inclusive. When sh_scale_rice is not present, it is inferred to be equal to 0. (See below for details within the box) 9.3.3.2 Rice Parameter Derivation Process for abs_remainder[] and dec_abs_level[] The inputs to this process are the base level baseLevel, the color component index cIdx, the luma location (x0, y0) specifying the top-left sample of the current transform block relative to the top-left sample of the current picture, the current coefficient scan location (xC, yC), the binary logarithm of the transform block width log2TbWidth, and the binary logarithm of the transform block height log2TbHeight. The output of this process is the rice parameter cRiceParam. Given an array AbsLevel[x][y] for a transform block with component index cIdx and top-left luma location (x0, y0), the variable locSumAbs is derived as specified by the following pseudocode process:

[0103]

number

[0104] The variable shift is derived as follows:

[0105]

number

[0106] The variable localSumAbs is updated as follows:

[0107]

number

[0108] Given the variable locSumAbs, the rice parameter cRiceParam is derived as specified in Table 128. The cRiceParam is then refined as follows:

[0109]

number

[0110] (The above is within the box)

[0099] The RRC method described above can be extended with a history of the Rice parameters used, as described below.

[0111]

[0100] A single counter per color component is used, and StatCoeff[3] is updated once per TU from the first non-zero Golomb-Rice coded transform coefficient (abs_remainder[] or dec_abs_level[]).

[0112]

[0101] When the first non-zero Golomb-Rice coded transform coefficient in a TU is coded as abs_remainder, the history counter (StatCoeff) for color component cIdx is updated as follows:

[0113]

number

[0114]

[0102] When the first non-zero Golomb-Rice coded transform coefficient in a TU is coded as abs_remainder, the history counter for color component cIdx is updated as follows:

[0115]

number

[0116]

[0103] The history counter StatCoeff[3] can be reset at the CTU level with a default value, or the history can be propagated between different CTUs.

[0117] The history Rice parameter values ​​are used in the template derivation, and section 9.3.3.2 implementation of this method is shown in the VVC specification text excerpt for section 9.3.3.2, where the green highlighted text relates to changes from CE-1.2 and the yellow highlighted text relates to the classification used in CE-1.4. The variable g_historyValue is derived from the history counter associated with the current color component id prior to the coding of the current TU.

[0118]

number

[0119] (See below for details within the box) 9.3.3.2 Rice Parameter Derivation Process for abs_remainder[] and dec_abs_level[] The inputs to this process are the base level baseLevel, the color component index cIdx, the luma location (x0, y0) specifying the top-left sample of the current transform block relative to the top-left sample of the current picture, the current coefficient scan location (xC, yC), the binary logarithm of the transform block width log2TbWidth, and the binary logarithm of the transform block height log2TbHeight. The output of this process is the rice parameter cRiceParam. Given an array AbsLevel[x][y] for a transform block with component index cIdx and top-left luma location (x0, y0), the variable locSumAbs is derived as specified by the following pseudocode process:

[0120]

number

[0121] The variable shift is derived as follows:

[0122]

number

[0123] The variable localSumAbs is updated as follows:

[0124]

number

[0125] Given the variable locSumAbs, the rice parameter cRiceParam is derived as specified in Table 128. The cRiceParam is then refined as follows:

[0126]

number

[0127] (The above is within the box) Video encoder 200 and video decoder 300 may be configured in accordance with the techniques of this disclosure as described below, which include modifications to the techniques described above.

[0128]

[0106] In some examples, for the local base slice derivation technique described above, the video encoder 200 and the video decoder 300 may derive a base level offset as a function of the input signal bit depth and / or slice type and use the baseLevel offset value to scale the locSumAbs value, as shown below.

[0129]

[0107] In some examples, the video encoder 200 and the video decoder 300 may derive the baseLevelOffset as follows:

[0130]

number

[0131]

[0108] In equation (1), the question mark operator (?) represents an equation of the form <condition>?X:Y, where if <condition> is true, the value of X is returned, but if <condition> is false, the value of Y is returned. The baseLevelOffset value represents the base level offset, bitDepth represents the bit depth of the video bitstream, T is a threshold value, and P1, P2, P3, and P4 are values ​​that can be predetermined or signaled in the bitstream.

[0132]

[0109] Video encoder 200 and video decoder 300 may use the base-level offset value to normalize localSumAbs as follows:

[0133]

number

[0134]

[0110] Generally, T represents a threshold value, and the P1, P2, P3, and P4 values ​​represent integer values. In some examples, T=12, P1=5, P2=10, P3=6, and P4=20. In some examples, T=12, P1=5, P2=10, P3=10, and P4=20. Other values ​​for T, P1, P2, P3, and P4 may also be used. T, P1, P2, P3, and P4 may be predefined, signaled in the bitstream, or derived based on various criteria.

[0135] In some examples, for the history-based slice derivation technique described above, the video encoder 200 and the video decoder 300 may preserve the status of the history counter StatCoeff[cIdx] across several blocks (e.g., several CTUs). Additionally or alternatively, the video encoder 200 and the video decoder 300 may derive the ScaleRice parameter (replacing the explicitly signaled sh_scale_rice syntax element) at the block level, e.g., the CTU level, from the current status of the StatCoeff[] counter. Thus, the video encoder 200 and the video decoder 300 do not need to explicitly signal the sh_rice_init syntax element.

[0136] In some examples, video encoder 200 and video decoder 300 may derive the ScaleRice parameter value through comparing the status of StatCoeff[ ] with a threshold and specifying an integer value for the parameter within a range of integer values. One such example of derivation is shown below.

[0137]

number

[0138] In some examples, T=4, P2=2 and P1=1.

[0139]

[0114] In some examples, the video encoder 200 and the video decoder 300 may derive the parameter ScaleRice independently for each color component (eg, luma, blue-hued chroma, and red-hued chroma).

[0140]

[0115] In some examples, when deriving a value for the ScaleRice parameter, the video encoder 200 and the video decoder 300 may take into account values ​​for history counters for two or more (e.g., all) color components through an aggregation function, e.g., a weighted function across the color components, as shown below.

[0141]

number

[0142]

[0116] In some examples, w0=2, w1=1, and w2=1.

[0143] In some examples, the video encoder 200 and the video decoder 300 may derive the parameter ScaleRice at the block level, e.g., at the level of a CTU, a TU, or a sub-TU. The video encoder 200 and the video decoder 300 may use the ScaleRice parameter when decoding data of a block of subsequently coded data. Alternatively, the video encoder 200 and the video decoder 300 may use the derived ScaleRice value in a manner delayed by a certain block size, e.g., to decode a block after the next block.

[0144]

[0118] Therefore, the checks for if(sps_high_bit_depth) and sh_scale_rice syntax elements can be removed from the syntax table.

[0145]

[0119] In some examples, video encoder 200 and video decoder 300 may derive the ScaleRice value through the process described above following initialization of StatCoeff with a default value or a signaled value.

[0146]

[0120] Figure 5 is a block diagram illustrating an example video encoder 200 that may implement the techniques of this disclosure. Figure 5 is provided for illustrative purposes and should not be considered limiting of the techniques broadly illustrated and described in this disclosure. For illustrative purposes, this disclosure describes video encoder 200 in accordance with VVC (ITU-T H.266 under development) and HEVC (ITU-T H.265) techniques. However, the techniques of this disclosure may be implemented by video encoding devices configured for other video coding standards and formats, such as AV1 and successors of the AV1 video coding format.

[0147] 5, the video encoder 200 includes a video data memory 230, a mode select 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, the mode select unit 202, the residual generation unit 204, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the filter unit 216, the DPB 218, and the entropy coding unit 220 may be implemented in one or more processors or processing circuits. For example, the units of video encoder 200 may be implemented as one or more circuits or logic elements, as part of a hardware circuit, or as part of a processor, ASIC, or FPGA. Moreover, video encoder 200 may include additional or alternative processors or processing circuits for performing these and other functions.

[0148]

[0122] Video data memory 230 may store video data to be encoded by components of video encoder 200. Video encoder 200 may receive video data stored in video data memory 230, for example, from video source 104 (FIG. 1). DPB 218 may serve as a reference picture memory that stores reference video data for use in predicting subsequent video data by video encoder 200. Video data memory 230 and DPB 218 may be formed by any of a variety of memory devices, such as synchronous dynamic random access memory (DRAM), including DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. Video data memory 230 and DPB 218 may be provided by the same memory device or separate memory devices. In various examples, video data memory 230 may be on-chip with other components of video encoder 200, as shown, or off-chip relative to those components.

[0149] In this disclosure, references to video data memory 230 should not be construed as limited to memory internal to video encoder 200 unless specifically so described, nor should they be construed as limited to memory external to video encoder 200 unless specifically so described. Instead, references to video data memory 230 should be understood as a reference memory that stores video data that video encoder 200 receives for encoding (e.g., video data for a current block to be encoded). Memory 106 of FIG. 1 may also provide temporary storage of outputs from various units of video encoder 200.

[0150] The various units in FIG. 5 are shown to aid in understanding the operations performed by video encoder 200. The units may be implemented as fixed-function circuits, programmable circuits, or a combination thereof. A fixed-function circuit refers to a circuit that provides a specific function and is preset with respect to the operations that may be performed. A programmable circuit refers to a circuit that can be programmed to perform various tasks and to provide flexible functionality in the operations that may be performed. For example, a programmable circuit may execute software or firmware that causes the programmable circuit to operate in a manner defined by the software or firmware instructions. A fixed-function circuit may execute software instructions (e.g., to receive parameters or output parameters), but the types of operations that the fixed-function circuit performs are generally invariant. In some examples, one or more of the units may be separate circuit blocks (fixed function or programmable), and in some examples, one or more of the units may be integrated circuits.

[0151]

[0125] Video encoder 200 may include an arithmetic logic unit (ALU), a basic functional unit (EFU), a programmable core formed from digital circuits, analog circuits, and / or programmable circuits. In examples in which the operations of video encoder 200 are implemented using software executed by programmable circuits, memory 106 (FIG. 1) may store software instructions (e.g., object code) that video encoder 200 receives and executes, or another memory (not shown) within video encoder 200 may store such instructions.

[0152]

[0126] The video data memory 230 is configured to store received video data. The video encoder 200 may retrieve pictures of the video data from the video data memory 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 memory 230 may be raw video data to be encoded.

[0153] The mode select unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra prediction unit 226. The mode select unit 202 may include additional functional units for performing video prediction according to other prediction modes. By way of example, the mode select unit 202 may include a palette unit, an intra block copy 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.

[0154]

[0128] The mode selection unit 202 generally coordinates multiple encoding passes to test combinations of encoding parameters and the resulting rate-distortion values ​​for such combinations. The encoding parameters may include partitioning of CTUs into CUs, prediction modes for CUs, transform types for residual data of CUs, quantization parameters for residual data of CUs, etc. The mode selection unit 202 may ultimately select a combination of encoding parameters that has a rate-distortion value that is better than the other tested combinations.

[0155] Video encoder 200 may partition a picture retrieved from video data memory 230 into a series of CTUs, encapsulating one or more CTUs in a slice. Mode select unit 202 may partition the CTUs of the picture according to a tree structure, such as the MTT structure, QTBT structure, superblock structure, or quadtree structure described above. As described above, video encoder 200 may form one or more CUs from partitioning the CTUs according to the tree structure. Such CUs may also be generally referred to as “video blocks” or “blocks.”

[0156]

[0130] Generally, the mode select unit 202 also controls its components (e.g., the motion estimation unit 222, the motion compensation unit 224, and the intra prediction unit 226) to generate a prediction block for a current block (e.g., the current CU, or in HEVC, the overlapping portion of the PU and TU). For inter prediction of the current block, the motion estimation unit 222 may perform motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously coded pictures stored in the DPB 218). In particular, the motion estimation unit 222 may calculate a value representing how similar a potential reference block is to the current block according to, for example, the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean squared difference (MSD), etc. The motion estimation unit 222 may generally perform these calculations using sample-by-sample differences between the current block and the reference block under consideration. Motion estimation unit 222 may identify the reference block with the lowest value obtained from these calculations, which indicates the reference block that most closely matches the current block.

[0157]

[0131] The motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of a reference block in a reference picture relative to the position of a current block in the current picture. The motion estimation unit 222 may then provide the motion vectors to the motion compensation unit 224. For example, in unidirectional inter prediction, the motion estimation unit 222 may provide a single motion vector, while in bidirectional inter prediction, the motion estimation unit 222 may provide two motion vectors. The motion compensation unit 224 may then generate a predictive block using the motion vectors. For example, the motion compensation unit 224 may use the motion vectors to retrieve data of the reference block. As another example, if the motion vectors have sub-sample precision, the motion compensation unit 224 may interpolate values ​​for the predictive block according to one or more interpolation filters. Moreover, in bidirectional inter prediction, the motion compensation unit 224 may retrieve data for the two reference blocks identified by the respective motion vectors and combine the retrieved data, for example, through sample-wise averaging or weighted averaging.

[0158]

[0132] When operating according to the AV1 video coding format, the motion estimation unit 222 and the motion compensation unit 224 may be configured to encode coding blocks of video data (e.g., both luma coding blocks and chroma coding blocks) using translational motion compensation, affine motion compensation, overlapped block motion compensation (OBMC), and / or compound inter-intra prediction.

[0159]

[0133] As another example, for intra prediction, or intra-predictive coding, intra prediction unit 226 may generate a predictive block from samples neighboring a current block. For example, in directional mode, intra prediction unit 226 may generally mathematically combine values ​​of neighboring samples and populate these calculated values ​​in a defined direction across the current block to produce the predictive block. As another example, in DC mode, intra prediction unit 226 may calculate the average of neighboring samples for the current block and generate a predictive block to include this resulting average for each sample of the predictive block.

[0160] When operating according to the AV1 video coding format, the intra prediction unit 226 may be configured to encode coding blocks of video data (e.g., both luma coding blocks and chroma coding blocks) using directional intra prediction, non-directional intra prediction, recursive filter intra prediction, chroma-from-luma (CFL) prediction, intra block copy (IBC), and / or color palette mode. The mode select unit 202 may include additional functional units for performing video prediction according to other prediction modes.

[0161]

[0135] The mode select unit 202 provides the prediction block to the residual generation unit 204. The residual generation unit 204 receives a raw, uncoded version of the current block from the video data memory 230 and receives the prediction block from the mode select unit 202. The residual generation unit 204 calculates sample-by-sample differences between the current block and the prediction block. The resulting sample-by-sample differences define a residual block for the current block. In some examples, the residual generation unit 204 may also determine differences between sample values ​​in the residual block to generate the residual block using residual differential pulse code modulation (RDPCM). In some examples, the residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0162] In examples in which mode select unit 202 partitions CUs into PUs, each PU may be associated with a luma prediction unit and a corresponding chroma prediction unit. Video encoder 200 and video decoder 300 may support PUs having various sizes. As indicated above, the size of a CU may refer to the size of the luma coding block of the CU, and the size of a PU may refer to the size of the luma prediction unit of the PU. Assuming that the size of a particular CU is 2N×2N, video encoder 200 may support a PU size of 2N×2N or N×N for intra prediction and a symmetric PU size of 2N×2N, 2N×N, N×2N, N×N, or the like for inter prediction. Video encoder 200 and video decoder 300 may also support asymmetric partitioning for PU sizes of 2N×nU, 2N×nD, nL×2N, and nR×2N for inter prediction.

[0163] In examples in which mode select unit 202 does not further partition CUs into PUs, each CU may be associated with a luma coding block and a corresponding chroma coding block. As described above, the size of a CU may refer to the size of the luma coding block of the CU. Video encoder 200 and video decoder 300 may support CU sizes of 2N×2N, 2N×N, or N×2N.

[0164]

[0138] In other video coding techniques, such as intra block copy mode coding, affine mode coding, and linear model (LM) mode coding, as some examples, mode select unit 202 generates a predictive block for the current block being coded via a respective unit associated with the coding technique. In some examples, such as palette mode coding, mode select unit 202 may not generate a predictive block, but instead generate syntax elements that indicate how the block should be reconstructed based on a selected palette. In such modes, mode select unit 202 may provide these syntax elements to entropy coding unit 220 to be coded.

[0165]

[0139] As described above, the residual generation unit 204 receives the video data for the current block and the corresponding predictive block. The residual generation unit 204 then generates a residual block for the current block. To generate the residual block, the residual generation unit 204 calculates sample-by-sample differences between the predictive block and the current block.

[0166]

[0140] Transform processing unit 206 applies 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 discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to the residual block. In some examples, transform processing unit 206 may perform multiple transforms on the residual block, e.g., a linear transform and a quadratic transform, such as a rotation transform. In some examples, transform processing unit 206 does not apply a transform to the residual block.

[0167] 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 horizontal / vertical transform combination, which may include a discrete cosine transform (DCT), an asymmetric discrete sine transform (ADST), an inverse ADST (e.g., a reverse ADST), and an identity transform (IDTX). When using an identity transform, the transform is skipped in one of the vertical or horizontal directions. In some examples, the transform processing may be skipped.

[0168]

[0142] The quantization unit 208 may quantize the transform coefficients in the transform coefficient block to produce a quantized transform coefficient block. The quantization unit 208 may quantize the transform coefficients of the transform coefficient block according to a quantization parameter (QP) value associated with the current block. The video encoder 200 (e.g., via the mode select unit 202) may 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 result in a loss of information, and therefore, the quantized transform coefficients may have lower precision than the original transform coefficients produced by the transform processing unit 206.

[0169]

[0143] The inverse quantization unit 210 and the inverse transform processing unit 212 may apply inverse quantization and inverse transform to the quantized transform coefficient block, respectively, to reconstruct a residual block from the transform coefficient block. The reconstruction unit 214 may produce a reconstructed block that corresponds to the current block (potentially with some distortion) based on the reconstructed residual block and the predictive block generated by the mode select unit 202. For example, the reconstruction unit 214 may add samples of the reconstructed residual block to corresponding samples from the predictive block generated by the mode select unit 202 to produce the reconstructed block.

[0170] Filter unit 216 may perform one or more filter operations on the reconstructed blocks. For example, filter unit 216 may perform a deblocking operation to reduce blockiness artifacts along the edges of a CU. The operations of filter unit 216 may be skipped in some examples.

[0171] When operating according to AV1, filter unit 216 may perform one or more filter operations on the reconstructed blocks. For example, filter unit 216 may perform a deblocking operation to reduce blockiness artifacts along the edges of a CU. In other examples, filter unit 216 may apply a constrained directional enhancement filter (CDEF), which may be applied after deblocking and may include application of a non-separable nonlinear low-pass directional filter based on the estimated edge direction. Filter unit 216 may also include a loop restoration filter, which may be applied after the CDEF and may include a separable symmetric normalized Wiener filter or a dual autoinduction filter.

[0172]

[0146] The video encoder 200 stores the reconstructed blocks in the DPB 218. For example, in examples where the operations of the filter unit 216 are not performed, the reconstruction unit 214 may store the reconstructed blocks in the DPB 218. In examples where the operations of the filter unit 216 are performed, the filter unit 216 may store the filtered reconstructed blocks in the DPB 218. The motion estimation unit 222 and the motion compensation unit 224 may retrieve reference pictures formed from the reconstructed (and potentially filtered) blocks from the DPB 218 to inter-predict blocks of a later-encoded picture. Furthermore, the intra-prediction unit 226 may use the reconstructed blocks in the DPB 218 of the current picture to intra-predict other blocks in the current picture.

[0173]

[0147] Generally, entropy encoding unit 220 may entropy encode syntax elements received from other functional components of video encoder 200. For example, entropy encoding unit 220 may entropy encode quantized transform coefficient blocks from quantization unit 208. As another example, entropy encoding unit 220 may entropy encode predictive syntax elements (e.g., motion information for inter-prediction or intra-mode information for intra-prediction) from mode select unit 202. Entropy encoding unit 220 may perform one or more entropy encoding operations on syntax elements, which are another example of video data, to generate entropy-encoded data. For example, entropy encoding unit 220 may perform a context-adaptive variable length coding (CAVLC) operation, a CABAC operation, a variable-to-variable (V2V) length coding operation, a syntax-based context-adaptive binary arithmetic coding (SBAC) operation, a probability interval partitioned entropy (PIPE) coding operation, an exponential-Golomb coding operation, or another type of entropy coding operation on the data. In some examples, entropy encoding unit 220 may operate in a bypass mode in which syntax elements are not entropy coded.

[0174] In some examples, entropy coding unit 220 may be configured to apply any or all of the Rice parameter derivation techniques described in this disclosure when entropy coding values ​​for one or more syntax elements of video data, e.g., transform coefficients. For example, entropy coding unit 220 may receive a transform block from quantization unit 208. For each coefficient in the transform block, entropy coding unit 220 may encode values ​​for one or more of a significant transform coefficient syntax element, a greater than 1 syntax element, a greater than 2 syntax element, a sign syntax element, and a residual value.

[0175]

[0149] When entropy encoding the residual value (or dec_abs_remainder value), among other values, the entropy encoding unit 220 may first calculate a local sum of absolute values ​​value as the sum of the absolute values ​​of neighboring coefficients relative to the current coefficient, e.g., as described above with respect to FIG. 2. The entropy encoding unit 220 may then calculate a base level offset value according to the bit depth and / or slice type for the slice including the current block, e.g., according to equation (1) above. The entropy encoding unit 220 may then calculate a normalized value for the local sum of absolute values ​​value using the base level offset value, e.g., according to equation (2) above. The entropy encoding unit 220 may then calculate a Rice parameter from the normalized value, e.g., according to Table 1 above. The entropy encoding unit 220 may then determine a Golomb-Rice code for the residual value using the Rice parameter and entropy encode each bit (bin) of the Golomb-Rice code.

[0176]

[0150] Video encoder 200 may output a bitstream that includes entropy-encoded syntax elements needed to reconstruct blocks of a slice or picture. In particular, entropy encoding unit 220 may output the bitstream.

[0177] According to AV1, entropy coding unit 220 may be configured as a symbol-to-symbol adaptive multi-symbol arithmetic coder. A syntax element in AV1 includes an alphabet of N elements, and a context (e.g., a probability model) includes a set of N probabilities. Entropy coding unit 220 may store the probabilities as an n-bit (e.g., 15-bit) cumulative distribution function (CDF). Entropy coding unit 22 may perform recursive scaling to update the context, using an update factor based on the alphabet size.

[0178]

[0152] The operations described above are described with respect to blocks. Such descriptions should be understood as being operations for luma coding blocks and / or chroma coding blocks. As described above, in some examples, the luma coding blocks and chroma coding blocks are luma and chroma components of a CU. In some examples, the luma coding blocks and chroma coding blocks are luma and chroma components of a PU.

[0179]

[0153] In some examples, operations performed with respect to luma coding blocks need not be repeated for chroma coding blocks. As one example, operations for identifying motion vectors (MVs) and reference pictures for luma coding blocks need not be repeated to identify MVs and reference pictures for chroma blocks. Rather, MVs for luma coding blocks may be scaled to determine MVs for chroma blocks, and the reference pictures may be the same. As another example, the intra prediction process may be the same for luma coding blocks and chroma coding blocks.

[0180]

[0154] Thus, the video encoder 200 represents an example of a device for encoding (and decoding) video data, the device including a memory configured to store the video data and one or more processors implemented in circuitry, the one or more processors configured to: calculate a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculate a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculate a normalized value for the sum of absolute values ​​using the base level offset value; and code the current coefficient using the normalized value for the sum of absolute values.

[0181]

[0155] Figure 6 is a block diagram illustrating an example video decoder 300 that may implement the techniques of this disclosure. Figure 6 is provided for illustrative purposes and is not intended to limit the techniques broadly illustrated and described in this disclosure. For illustrative purposes, this disclosure describes the video decoder 300 in accordance with VVC (ITU-T H.266 under development) and HEVC (ITU-T H.265) techniques. However, the techniques of this disclosure may be implemented by video coding devices configured for other video coding standards.

[0182] 6, the video decoder 300 includes a coded 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 decoded picture buffer (DPB) 314. Any or all of the CPB memory 320, the entropy decoding unit 302, the prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, the filter unit 312, and the DPB 314 may be implemented in one or more processors or processing circuits. For example, the units of the video decoder 300 may be implemented as one or more circuits or logic elements, as part of a hardware circuit, or as part of a processor, ASIC, or FPGA. Moreover, the video decoder 300 may include additional or alternative processors or processing circuits for performing these and other functions.

[0183] Prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. Prediction processing unit 304 may include additional units for performing prediction according to other prediction modes. By way of example, prediction processing unit 304 may include a palette unit, an intra block copy unit (which may form part of motion compensation unit 316), an affine unit, a linear model (LM) unit, etc. In other examples, video decoder 300 may include more, fewer, or different functional components.

[0184] When operating in accordance with AV1, the compensation unit 316 may be configured to decode coding blocks of the video data (e.g., both luma coding blocks and chroma coding blocks) using translational motion compensation, affine motion compensation, OBMC, and / or hybrid inter-intra prediction, as described above. The intra prediction unit 318 may be configured to decode coding blocks of the video data (e.g., both luma coding blocks and chroma coding blocks) using directional intra prediction, non-directional intra prediction, recursive filter intra prediction, CFL, intra block copy (IBC), and / or color palette mode, as described above.

[0185]

[0159] The CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of the video decoder 300. The video data stored in the CPB memory 320 may be obtained, for example, from the computer-readable medium 110 (FIG. 1). The CPB memory 320 may include a CPB that stores encoded video data (e.g., syntax elements) from the encoded video bitstream. The CPB memory 320 may also store video data other than syntax elements of coded pictures, such as temporary data representing output from various units of the video decoder 300. The DPB 314 generally stores decoded pictures that the video decoder 300 may output and / or use as reference video data when decoding subsequent data or pictures of the encoded video bitstream. CPB memory 320 and DPB 314 may be formed by any of a variety of memory devices, such as synchronous dynamic random access memory (DRAM), including DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. CPB memory 320 and DPB 314 may be provided by the same memory device or separate memory devices. In various examples, CPB memory 320 may be on-chip with other components of video decoder 300 or off-chip relative to those components.

[0186] Additionally or alternatively, in some examples, video decoder 300 may retrieve coded video data from memory 120 (FIG. 1). That is, memory 120 may store data as described above in conjunction with CPB memory 320. Similarly, memory 120 may store instructions to be executed by video decoder 300 when some or all of the functionality of video decoder 300 is implemented in software to be executed by processing circuitry of video decoder 300.

[0187] The various units shown in FIG. 6 are presented to aid in understanding the operations performed by video decoder 300. The units may be implemented as fixed-function circuits, programmable circuits, or a combination thereof. As with FIG. 5, a fixed-function circuit refers to a circuit that provides a specific function and is preset with respect to the operations that may be performed. A programmable circuit refers to a circuit that may be programmed to perform various tasks and to provide flexible functionality in the operations that may be performed. For example, a programmable circuit may execute software or firmware that causes the programmable circuit to operate in a manner defined by the software or firmware instructions. A fixed-function circuit may execute software instructions (e.g., to receive parameters or output parameters), but the types of operations that the fixed-function circuit performs are generally invariant. In some examples, one or more of the units may be separate circuit blocks (fixed function or programmable), and in some examples, one or more of the units may be an integrated circuit.

[0188]

[0162] Video decoder 300 may include a programmable core formed from ALUs, EFUs, digital circuits, analog circuits, and / or programmable circuits. In examples in which the operations of video decoder 300 are performed by software executing on programmable circuits, on-chip or off-chip memory may store instructions (e.g., object code) of the software that video decoder 300 receives and executes.

[0189]

[0163] The entropy decoding unit 302 may receive the encoded video data from the CPB and entropy decode the video data to recover 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 may generate decoded video data based on the syntax elements extracted from the bitstream.

[0190] In some examples, entropy decoding unit 302 may be configured to apply any or all of the Rice parameter derivation techniques described in this disclosure when entropy decoding values ​​for one or more syntax elements of video data, e.g., transform coefficients. For example, entropy decoding unit 302 may receive entropy-encoded values ​​for one or more of a significant transform coefficient syntax element, a syntax element greater than 1, a syntax element greater than 2, a sign syntax element, and a residual value.

[0191]

[0165] When decoding the residual value (or dec_abs_remainder value) for the current coefficient, among other values, the entropy decoding unit 302 may entropy decode a Golomb-Rice code from the bitstream for the residual value of the current coefficient. The entropy decoding unit 302 may then calculate a local sum of absolute values ​​value as the sum of the absolute values ​​of neighboring coefficients relative to the current coefficient, e.g., as described above with respect to FIG. 2. The entropy decoding unit 302 may then calculate a base-level offset value according to the bit depth and / or slice type for the slice including the current block, e.g., according to equation (1) above. The entropy decoding unit 302 may calculate a normalized value for the local sum of absolute values ​​value using the base-level offset value, e.g., according to equation (2) above. The entropy decoding unit 302 may then calculate a Rice parameter from the normalized value, e.g., according to Table 1 above. The entropy decoding unit 302 may then binarize the residual value from the Golomb-Rice code using the Rice parameter. The entropy decoding unit 302 may concatenate the significant coefficient value, the values ​​greater than 1, the values ​​greater than 2, and the residual value to reconstruct the current coefficient.

[0192]

[0166] Generally, video decoder 300 reconstructs a picture on a block-by-block basis. Video decoder 300 may perform a reconstruction operation on each block individually (here, the block currently being reconstructed, i.e., decoded, may be referred to as the "current block").

[0193]

[0167] The entropy decoding unit 302 may entropy decode syntax elements defining the quantized transform coefficients of a quantized transform coefficient block, as well as transform information such as a quantization parameter (QP) and / or one or more transform mode indications. The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine the degree of quantization and, similarly, the degree of inverse quantization to apply. The inverse quantization unit 306 may perform, for example, a bitwise left shift operation to inverse quantize the quantized transform coefficients. The inverse quantization unit 306 may thereby form a transform coefficient block including the transform coefficients.

[0194]

[0168] After the inverse quantization unit 306 forms the transform coefficient blocks, the inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient blocks to generate residual blocks 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 rotational transform, an inverse transform, or another inverse transform to the transform coefficient blocks.

[0195]

[0169] Furthermore, prediction processing unit 304 generates a predictive block according to the prediction information syntax element entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax element indicates that the current block is inter-predicted, motion compensation unit 316 may generate a predictive block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which to retrieve a reference block, as well as a motion vector that identifies the location of the reference block in the reference picture relative to the location of the current block in the current picture. Motion compensation unit 316 may generally perform the inter-prediction process in a manner substantially similar to that described with respect to motion compensation unit 224 (FIG. 5).

[0196]

[0170] As another example, if the prediction information syntax element indicates that the current block is intra-predicted, intra prediction unit 318 may generate a predictive block according to the intra-prediction mode indicated by the prediction information syntax element. Again, intra prediction unit 318 may generally perform the intra-prediction process in a manner substantially similar to that described with respect to intra prediction unit 226 (FIG. 5). Intra prediction unit 318 may retrieve data of neighboring samples for the current block from DPB 314.

[0197]

[0171] The reconstruction unit 310 may reconstruct the current block using the predictive block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the predictive block to reconstruct the current block.

[0198]

[0172] Filter unit 312 may perform one or more filter operations on the reconstructed blocks. For example, filter unit 312 may perform a deblocking operation to reduce blockiness artifacts along the edges of the reconstructed blocks. The operations of filter unit 312 are not necessarily performed in all instances.

[0199] The video decoder 300 may store the reconstructed blocks in the DPB 314. For example, in examples where the operations of the filter unit 312 are not performed, the reconstruction unit 310 may store the reconstructed blocks in the DPB 314. In examples where the operations of the filter unit 312 are performed, the filter unit 312 may store the filtered reconstructed blocks in the DPB 314. As described above, the DPB 314 may provide reference information to the prediction processing unit 304, such as samples of the current picture for intra prediction and previously decoded pictures for subsequent motion compensation. Moreover, the video decoder 300 may output the decoded pictures (e.g., decoded video) from the DPB 314 for subsequent presentation on a display device, such as the display device 118 of FIG. 1 .

[0200]

[0174] Thus, the video decoder 300 represents an example of a device for decoding video data, the device including a memory configured to store the video data and one or more processors implemented in a circuit, the one or more processors configured to: calculate a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculate a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculate a normalized value for the sum of absolute values ​​using the base level offset value; and code the current coefficient using the normalized value for the sum of absolute values.

[0201] 7 is a flowchart illustrating an example method for encoding a current block in accordance with the techniques of this disclosure. The current block may comprise a current CU. Although described with respect to video encoder 200 (FIGS. 1 and 5), it should be understood that other devices may be configured to implement a method similar to that of FIG.

[0202] In this example, video encoder 200 first predicts the current block (350). For example, video encoder 200 may form a predictive block for the current block. Video encoder 200 may then calculate a residual block for the current block (352). To calculate the residual block, video encoder 200 may calculate the difference between the original uncoded block and the predictive block for the current block. Video encoder 200 may then transform the residual block and quantize the transform coefficients of the residual block (354). Next, video encoder 200 may scan the quantized transform coefficients of the residual block (356). During or following the scan, video encoder 200 may entropy code the transform coefficients (358). For example, video encoder 200 may code the transform coefficients using CAVLC or CABAC. When entropy coding the transform coefficients, video encoder 200 may apply any or all of the Rice parameter derivation techniques described in this disclosure. Video encoder 200 may then output the entropy-coded data for the block (360).

[0203] Video encoder 200 may also decode the current block after encoding it to use the decoded version of the current block as reference data for later-coded data (e.g., in inter-prediction or intra-prediction modes). Accordingly, video encoder 200 may dequantize and inverse transform coefficients to reconstruct a residual block (362). Video encoder 200 may combine the residual block with the predictive block to form a decoded block (364). Video encoder 200 may then store the decoded block in DPB 218 (366).

[0204] 8 is a flowchart illustrating an example method for decoding a current block of video data in accordance with the techniques of this disclosure. The current block may comprise a current CU. Although described with respect to video decoder 300 (FIGS. 1 and 6), it should be understood that other devices may be configured to implement a method similar to that of FIG.

[0205] 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 that corresponds to the current block (370). The video decoder 300 may entropy decode the entropy-coded data to determine the prediction information for the current block and to regenerate the transform coefficients of the residual block (372). The video decoder 300 may apply any or all of the Rice parameter derivation techniques described in this disclosure when entropy-decoding the transform coefficients.

[0206]

[0180] The video decoder 300 may predict the current block, e.g., using the intra-prediction or inter-prediction mode indicated by the prediction information for the current block, to calculate a predictive block for the current block (374). The video decoder 300 may then inverse scan the reconstructed transform coefficients to create a block of quantized transform coefficients (376). The video decoder 300 may then dequantize the transform coefficients and apply an inverse transform to the transform coefficients to produce a residual block (378). The video decoder 300 may finally decode the current block by combining the predictive block and the residual block (380).

[0207]

[0181] Figure 9 is a flowchart illustrating an example method for encoding video data in accordance with the techniques of this disclosure. The method of Figure 9 may generally correspond to step 358 of Figure 7.

[0208]

[0182] First, video encoder 200 may determine current coefficient values ​​for a current block of video data (400). Video encoder 200 may partition the current coefficient values ​​into respective values ​​for syntax elements, such as significant coefficient syntax elements, syntax elements greater than 1, syntax elements greater than 2, residual syntax elements, and sign syntax elements. The method of FIG. 9 describes encoding the values ​​of residual syntax elements. However, other syntax elements, such as the dec_abs_level[] syntax element, may be encoded using this method or a similar method.

[0209]

[0183] Video encoder 200 may then calculate a local sum of absolute values ​​(402). For example, video encoder 200 may determine absolute values ​​for the values ​​of coefficients neighboring the current coefficient. For the example of Figure 2, for example, the neighboring coefficients may include a right neighboring coefficient, a two-to-the-right neighboring coefficient, a lower-right neighboring coefficient, a lower neighboring coefficient, and a two-to-the-lower neighboring coefficient. Video encoder 200 may add up the sum of the absolute values ​​of the neighboring coefficients as the local sum of absolute values ​​value.

[0210]

[0184] Video encoder 200 may then calculate a base level offset value according to the bit depth and / or slice type for the slice that includes the current block (404). For example, video encoder 200 may calculate a base level offset value (baseLevelOffset) according to the following:

[0211]

number

[0212] Accordingly, the video encoder 200 may determine whether a bit depth (bitDepth) for the video data is greater than a threshold T. If the bit depth is greater than the threshold, the video encoder 200 may determine whether the slice type is intra-predicted. If the slice type is intra-predicted, the video encoder 200 may determine that the base level offset value is P1. If the slice type is not intra-predicted (e.g., is inter-predicted, such as a P slice or a B slice), the video encoder 200 may determine that the base level offset value is P2. If the bit depth is less than or equal to the threshold, the video encoder 200 may also determine whether the slice type is intra-predicted. If the slice type is intra-predicted, the video encoder 200 may determine that the base level offset value is P3. If the slice type is not intra-predicted (e.g., is inter-predicted, such as a P slice or a B slice), the video encoder 200 may determine that the base level offset value is P4. P1, P2, P3, and P4 may be predefined values, or the video encoder 200 may determine values ​​for P1, P2, P3, and P4 and signal the determined values ​​in the bitstream.

[0213]

[0185] Video encoder 200 may then normalize the local sum of absolute values ​​using the calculated base-level offset value (406). For example, video encoder 200 may calculate:

[0214]

number

[0215] In this example, locSumAbs (local sum of absolute values) is updated using clipping operation Clip3 and using the calculated baseLevelOffset value, eg, according to VVC.

[0216]

[0186] Video encoder 200 may then determine the Rice parameters from the normalized values ​​(408). For example, video encoder 200 may use Table 1 as a lookup table to determine the Rice parameters.

[0217]

[0187] Video encoder 200 may then determine a Golomb-Rice code for the coefficient values ​​(e.g., residual values) using the Rice parameters (410). The Golomb-Rice code may be a series of bits (bins). Video encoder 200 may then entropy encode the Golomb-Rice code (412).

[0218]

[0188] Thus, the method of Figure 9 represents one example of a method for encoding video data, the method including: calculating a sum of absolute values ​​of a plurality of coefficients adjacent to a current coefficient for a current block of the video data; calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculating a normalized value for the sum of absolute values ​​using the base level offset value; and coding the current coefficient using the normalized value for the sum of absolute values.

[0219]

[0189] Figure 10 is a flowchart illustrating an example method for decoding video data in accordance with the techniques of this disclosure. The method of Figure 10 may generally correspond to step 372 of Figure 8.

[0220]

[0190] First, video decoder 300 may entropy decode a Golomb-Rice code for a current coefficient of a current block of video data (420). The Golomb-Rice code may correspond to a residual value of the current coefficient, which may further include a significant coefficient syntax element, a syntax element greater than 1, a syntax element greater than 2, and a sign syntax element. Although the example of FIG. 10 is directed to decoding a residual value for the current coefficient, the method of FIG. 10 may also be used to decode other values, such as a value for the dec_abs_level[] syntax element.

[0221]

[0191] The video decoder 300 may then calculate a local sum of absolute values ​​(422). For example, the video decoder 300 may determine absolute values ​​for the values ​​of neighboring coefficients relative to the current coefficient. For the example of Figure 2, for example, the neighboring coefficients may include a right neighboring coefficient, a two-neighboring coefficient to the right, a lower-right neighboring coefficient, a lower neighboring coefficient, and a two-neighboring coefficient below. The video decoder 300 may add up the sum of the absolute values ​​of the neighboring coefficients as the local sum of absolute values ​​value.

[0222]

[0192] Video decoder 300 may then calculate a base level offset value according to the bit depth and / or slice type for the slice that includes the current block (424). For example, video decoder 300 may calculate a base level offset value (baseLevelOffset) according to the following:

[0223]

number

[0224] Accordingly, the video decoder 300 may determine whether a bit depth (bitDepth) for the video data is greater than a threshold T. If the bit depth is greater than the threshold, the video decoder 300 may determine whether the slice type is intra-predicted. If the slice type is intra-predicted, the video decoder 300 may determine that the base level offset value is P1. If the slice type is not intra-predicted (e.g., is inter-predicted, such as a P slice or a B slice), the video decoder 300 may determine that the base level offset value is P2. If the bit depth is less than or equal to the threshold, the video decoder 300 may also determine whether the slice type is intra-predicted. If the slice type is intra-predicted, the video decoder 300 may determine that the base level offset value is P3. If the slice type is not intra-predicted (e.g., is inter-predicted, such as a P slice or a B slice), the video decoder 300 may determine that the base level offset value is P4. P1, P2, P3, and P4 may be predefined values, or the video decoder 300 may decode values ​​for P1, P2, P3, and P4 from the bitstream.

[0225]

[0193] The video decoder 300 may then normalize the local sum of absolute values ​​using the calculated base-level offset value (426). For example, the video decoder 300 may calculate:

[0226]

number

[0227] In this example, locSumAbs (local sum of absolute values) is updated using clipping operation Clip3 and using the calculated baseLevelOffset value, eg, according to VVC.

[0228]

[0194] The video decoder 300 may then determine the Rice parameters from the normalized values ​​(428). For example, the video decoder 300 may use Table 1 as a lookup table to determine the Rice parameters.

[0229]

[0195] The video decoder 300 may then use the Rice parameters to form binarized (binary) values ​​representing the residual values ​​from the Golomb-Rice codes (430). The video decoder 300 may further reconstruct the coefficient values ​​from the binarized values ​​(432). For example, the video decoder 300 may concatenate values ​​for the significant coefficient syntax elements, values ​​for syntax elements greater than 1, values ​​for syntax elements greater than 2, and values ​​for the residual values.

[0230]

[0196] Thus, the method of Figure 9 represents one example of a method for decoding video data, the method including: calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculating a normalized value for the sum of absolute values ​​using the base level offset value; and coding the current coefficient using the normalized value for the sum of absolute values.

[0231]

[0197] Some examples of various techniques of the present disclosure are summarized in the following paragraphs.

[0232]

[0198] Clause 1: A method for coding video data, the method comprising: calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculating a normalized value for the sum of absolute values ​​using the base level offset value; and coding the current coefficient using the normalized value for the sum of absolute values.

[0233]

[0199] Clause 2: The method of clause 1, wherein the plurality of neighboring coefficients includes five neighboring coefficients to the current coefficient.

[0234]

[0200] Clause 3: A method according to any of clauses 1 and 2, wherein the plurality of adjacent coefficients includes two right adjacent coefficients to the current coefficient, two below adjacent coefficients to the current coefficient, and one below-left adjacent coefficient to the current coefficient.

[0235]

[0201] Clause 4: A method according to any one of clauses 1 to 3, wherein calculating the base level offset value comprises calculating baseLevelOffset=(bitDepth>T)?(isIntra()?P1:P2):(isIntra()?P3:P4), where bitDepth comprises a bit depth for the video data, isIntra() returns a true value if the slice type for the slice is an intra-predicted slice or a false value if the slice type for the slice is an inter-predicted slice, and T, P1, P2, P3, and P4 comprise respective input values.

[0236]

[0202] Clause 5: The method of clause 4, wherein input values ​​for T, P1, P2, P3, and P4 are predetermined.

[0237]

[0203] Clause 6: The method of clause 4, wherein the input values ​​for T, P1, P2, P3, and P4 are signaled in the bitstream.

[0238]

[0204] Clause 7: The method of any one of clauses 4 to 6, wherein T=12, P1=5, P2=10, P3=6, and P4=20.

[0239]

[0205] Clause 8: The method of any one of clauses 4 to 6, wherein T=12, P1=5, P2=10, P3=10, and P4=20.

[0240]

[0206] Clause 9: A method according to any of clauses 1 to 8, wherein calculating a normalized value for the sum of absolute values ​​comprises calculating Clip3(0, 31, locSumAbs-baseLevelOffset), where locSumAbs comprises the sum of absolute values ​​and baseLevelOffset comprises the base level offset value.

[0241]

[0207] Clause 10: A method for coding video data, the method comprising: maintaining a history counter representing a history of Rice parameters used to code coefficients of a color component of the video data; deriving a Rice parameter scaling value for a block of the color component of the video data from a current value for the history counter without explicitly coding a value for the Rice parameter scaling value; calculating a sum of the absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient of the block; calculating a scaled value for the sum of the absolute values ​​using the Rice parameter scaling value; and coding the current coefficient using the scaled value for the sum of the absolute values.

[0242]

[0208] Clause 11: A method comprising a combination of the method described in any one of clauses 1 to 9 and the method described in clause 10.

[0243]

[0209] Clause 12: A method according to any of clauses 10 and 11, wherein deriving the Rice parameter scaling value comprises calculating (StatCoeff[idx]≧T)?P2:P1, where idx represents a color component, StatCoeff[idx] represents a current value for a history counter, and T, P1, and P2 represent input values.

[0244]

[0210] Clause 13: The method of clause 12, wherein input values ​​for T, P1, and P2 are predetermined.

[0245]

[0211] Clause 14: The method of clause 12, wherein the input values ​​for T, P1, and P2 are signaled in the video data.

[0246]

[0212] Clause 15: The method of any one of clauses 12 to 14, wherein T=4, P2=2 and P1=1.

[0247]

[0213] Clause 16: A method as described in any of clauses 10 and 11, wherein deriving a Rice parameter scaling value comprises calculating an aggregated history counter value representing an aggregation of history counters, including history counters for all color components, including color components, of the video data, and deriving the Rice parameter scaling value using the aggregated history counter value.

[0248]

[0214] Clause 17: The method of clause 16, wherein calculating the aggregated history counter value comprises calculating ((StatCoeff[0]*w0)+StatCoeff[1]*w1+StatCoeff[2]*w2) / (w1+w2+w3), where StatCoeff[0] represents a first history counter of the history counters for a first color component of the color components, StatCoeff[1] represents a second history counter of the history counters for a second color component of the color components, StatCoeff[2] represents a third history counter of the history counters for a third color component of the color components, and w1, w2, and w3 represent respective weighting values.

[0249]

[0215] Clause 18: The method of clause 17, wherein deriving a Rice parameter scaling value comprises deriving a Rice parameter scaling value using (StatCoefAverage≧T)?P2:P1, where StatCoefAverage represents aggregated historical counter values, and T, P1, and P2 represent input values.

[0250]

[0216] Clause 19: The method of clause 18, wherein input values ​​for T, P1, and P2 are predetermined.

[0251]

[0217] Clause 20: The method of clause 18, wherein the input values ​​for T, P1, and P2 are signaled in the video data.

[0252]

[0218] Clause 21: The method of any one of clauses 18 to 20, wherein T=4, P2=2 and P1=1.

[0253]

[0219] Clause 22: A method according to any one of clauses 18 to 21, wherein w0=2, w1=1, and w2=1.

[0254]

[0220] Clause 23: The method of any of clauses 10 to 22, wherein the blocks comprise coding tree units (CTUs).

[0255]

[0221] Clause 24: The method of any of clauses 10 to 22, wherein the block comprises a transform unit (TU).

[0256]

[0222] Clause 25: The method of any of clauses 10 to 22, wherein the blocks comprise sub-transform units (sub-TUs).

[0257]

[0223] Clause 26: A method according to any of clauses 10 to 22, wherein the block comprises a first block, the Rice parameter scaling value comprises a first Rice parameter scaling value, and the method further comprises deriving a second Rice parameter scaling value for a second block using the first Rice parameter scaling value.

[0258]

[0224] Clause 27: A method for coding video data, the method comprising: calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculating a normalized value for the sum of absolute values ​​using the base level offset value; and coding the current coefficient using the normalized value for the sum of absolute values.

[0259]

[0225] Clause 28: The method of clause 27, wherein the plurality of neighboring coefficients includes five neighboring coefficients to the current coefficient.

[0260]

[0226] Clause 29: The method of clause 27, wherein the plurality of adjacent coefficients includes two right adjacent coefficients to the current coefficient, two below adjacent coefficients to the current coefficient, and one below-left adjacent coefficient to the current coefficient.

[0261]

[0227] Clause 30: The method of clause 27, wherein calculating the base level offset value comprises calculating baseLevelOffset=(bitDepth>T)?(isIntra()?P1:P2):(isIntra()?P3:P4), where bitDepth comprises a bit depth for the video data, isIntra() returns a true value if the slice type for the slice is an intra-predicted slice or a false value if the slice type for the slice is an inter-predicted slice, and T, P1, P2, P3, and P4 comprise respective input values.

[0262]

[0228] Clause 31: The method of clause 30, wherein input values ​​for T, P1, P2, P3, and P4 are predetermined.

[0263]

[0229] Clause 32: The method of clause 30, wherein input values ​​for T, P1, P2, P3, and P4 are signaled in the bitstream.

[0264]

[0230] Clause 33: The method described in clause 30, wherein T=12, P1=5, P2=10, P3=6, and P4=20.

[0265]

[0231] Clause 34: The method described in clause 30, wherein T=12, P1=5, P2=10, P3=10, and P4=20.

[0266]

[0232] Clause 35: The method described in Clause 27, wherein calculating a normalized value for the sum of absolute values ​​comprises calculating Clip3(0, 31, locSumAbs-baseLevelOffset), where locSumAbs comprises the sum of absolute values ​​and baseLevelOffset comprises the base level offset value.

[0267]

[0233] Clause 36: A method of coding video data, the method comprising: maintaining a history counter representing a history of Rice parameters used to code coefficients of a color component of the video data; deriving a Rice parameter scaling value for a block of the color component of the video data from a current value for the history counter without explicitly coding a value for the Rice parameter scaling value; calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient of the block; calculating a scaled value for the sum of absolute values ​​using the Rice parameter scaling value; and coding the current coefficient using the scaled value for the sum of absolute values.

[0268]

[0234] Clause 37: The method of clause 36, wherein deriving the Rice parameter scaling value comprises calculating (StatCoeff[idx]≧T)?P2:P1, where idx represents a color component, StatCoeff[idx] represents a current value for a history counter, and T, P1, and P2 represent input values.

[0269]

[0235] Clause 38: The method of clause 37, wherein input values ​​for T, P1, and P2 are predetermined.

[0270]

[0236] Clause 39: The method of clause 37, wherein the input values ​​for T, P1, and P2 are signaled in the video data.

[0271]

[0237] Clause 40: The method of clause 37, wherein T=4, P2=2 and P1=1.

[0272]

[0238] Clause 41: The method described in Clause 36, wherein deriving the Rice parameter scaling value comprises calculating an aggregated history counter value representing an aggregation of history counters, including history counters for all color components including color components of the video data, and deriving the Rice parameter scaling value using the aggregated history counter value.

[0273]

[0239] Clause 42: The method of clause 41, wherein calculating the aggregated history counter value comprises calculating ((StatCoeff[0]*w0)+StatCoeff[1]*w1+StatCoeff[2]*w2) / (w1+w2+w3), where StatCoeff[0] represents a first history counter of the history counters for a first color component of the color components, StatCoeff[1] represents a second history counter of the history counters for a second color component of the color components, StatCoeff[2] represents a third history counter of the history counters for a third color component of the color components, and w1, w2, and w3 represent respective weighting values.

[0274]

[0240] Clause 43: The method of clause 42, wherein deriving a Rice parameter scaling value comprises deriving a Rice parameter scaling value using (StatCoefAverage≧T)?P2:P1, where StatCoefAverage represents aggregated historical counter values, and T, P1, and P2 represent input values.

[0275]

[0241] Clause 44: The method of clause 43, wherein input values ​​for T, P1, and P2 are predetermined.

[0276]

[0242] Clause 45: The method of clause 43, wherein the input values ​​for T, P1, and P2 are signaled in the video data.

[0277]

[0243] Clause 46: The method according to clause 43, wherein T=4, P2=2 and P1=1.

[0278]

[0244] Clause 47: The method according to clause 43, wherein w0=2, w1=1, and w2=1.

[0279]

[0245] Clause 48: The method of clause 36, wherein the block comprises a coding tree unit (CTU).

[0280]

[0246] Clause 49: The method of clause 36, wherein the block comprises a transform unit (TU).

[0281]

[0247] Clause 50: The method of clause 36, wherein the block comprises sub-transform units (sub-TUs).

[0282]

[0248] Clause 51: The method described in Clause 36, wherein the block comprises a first block, the Rice parameter scaling value comprises a first Rice parameter scaling value, and the method further comprises deriving a second Rice parameter scaling value for a second block using the first Rice parameter scaling value.

[0283]

[0249] Clause 52: The method of any of clauses 1 to 51, wherein coding comprises decoding.

[0284]

[0250] Clause 53: The method of any of clauses 1 to 52, wherein coding comprises encoding.

[0285]

[0251] Clause 54: A device for coding video data, the device comprising one or more means for performing the method according to any one of clauses 1 to 53.

[0286]

[0252] Clause 55: A device according to clause 54, wherein the one or more means comprise one or more processors implemented in circuitry.

[0287]

[0253] Clause 56: A device according to any one of clauses 54 to 55, further comprising a display configured to display the decoded video data.

[0288]

[0254] Clause 57: A device according to any one of clauses 54 to 56, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0289]

[0255] Clause 58: A device described in any of clauses 54 to 57, further comprising a memory configured to store video data.

[0290]

[0256] Clause 59: A computer-readable storage medium storing instructions which, when executed, cause a processor of a device for decoding video data to perform a method described in any of clauses 1 to 53.

[0291]

[0257] Clause 60: A device for coding video data, comprising: means for calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; means for calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; means for calculating a normalized value for the sum of absolute values ​​using the base level offset value; and means for coding the current coefficient using the normalized value for the sum of absolute values.

[0292]

[0258] Clause 61: A device for coding video data, comprising: means for maintaining a history counter representing a history of Rice parameters used to code coefficients of a color component of the video data; means for deriving a Rice parameter scaling value for a block of the color component of the video data from a current value for the history counter without explicitly coding a value for the Rice parameter scaling value; means for calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient of the block; means for calculating a scaled value for the sum of absolute values ​​using the Rice parameter scaling value; and means for coding the current coefficient using the scaled value for the sum of absolute values.

[0293]

[0259] Clause 62: A method for coding video data, the method comprising: calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculating a normalized value for the sum of absolute values ​​using the base level offset value; and coding the current coefficient using the normalized value for the sum of absolute values.

[0294]

[0260] Clause 63: The method of clause 62, wherein the plurality of neighboring coefficients includes five neighboring coefficients to the current coefficient.

[0295]

[0261] Clause 64: The method of clause 62, wherein the plurality of adjacent coefficients includes two right adjacent coefficients to the current coefficient, two below adjacent coefficients to the current coefficient, and one below-left adjacent coefficient to the current coefficient.

[0296]

[0262] Clause 65: The method of clause 62, wherein calculating the base level offset value comprises calculating baseLevelOffset=(bitDepth>T)?(isIntra()?P1:P2):(isIntra()?P3:P4), where bitDepth comprises a bit depth for the video data, isIntra() returns a true value if the slice type for the slice is an intra-predicted slice or a false value if the slice type for the slice is an inter-predicted slice, and T, P1, P2, P3, and P4 comprise respective input values.

[0297]

[0263] Clause 66: The method according to clause 65, wherein T=12.

[0298]

[0264] Clause 67: The method described in clause 66, wherein P1=5, P2=10, P3=6, and P4=20.

[0299]

[0265] Clause 68: The method described in clause 66, wherein P1=5, P2=10, P3=10, and P4=20.

[0300]

[0266] Clause 69: The method of clause 65, wherein input values ​​for T, P1, P2, P3, and P4 are predetermined.

[0301]

[0267] Clause 70: The method of clause 65, wherein input values ​​for T, P1, P2, P3, and P4 are signaled in the bitstream.

[0302]

[0268] Clause 71: The method described in Clause 62, wherein calculating a normalized value for the sum of absolute values ​​comprises calculating Clip3(0, 31, locSumAbs-baseLevelOffset), where locSumAbs comprises the sum of absolute values ​​and baseLevelOffset comprises the base level offset value.

[0303]

[0269] Clause 72: The method described in Clause 62, wherein coding the current coefficient using a normalized value for the sum of absolute values ​​comprises determining a Rice parameter corresponding to the normalized value for the sum of absolute values, and binarizing the value for the current coefficient using the Rice parameter to form a binarized value.

[0304]

[0270] Clause 73: The method of clause 62, wherein the current block comprises a first block, the color component of the video data comprises a first block, the sum of absolute values ​​comprises a first sum of absolute values, and the plurality of adjacent coefficients comprises a first plurality of adjacent coefficients, and the method further comprises maintaining a history counter representing a history of Rice parameters used to code coefficients of the color component of the video data, deriving a Rice parameter scaling value for a second block of the color component of the video data from a current value for the history counter without explicitly coding a value for the Rice parameter scaling value, calculating a second sum of absolute values ​​of the second plurality of adjacent coefficients for a second coefficient of the second block, calculating a scaled value for the second sum of absolute values ​​using the Rice parameter scaling value, and coding a second coefficient of the second block using the scaled value for the second sum of absolute values.

[0305]

[0271] Clause 74: The method described in clause 12, wherein deriving the Rice parameter scaling value comprises calculating (StatCoeff[idx]≧T)?P2:P1, where idx represents a color component, StatCoeff[idx] represents a current value for a history counter, and T, P1, and P2 represent input values.

[0306]

[0272] Clause 75: The method of clause 13, wherein input values ​​for T, P1, and P2 are predetermined.

[0307]

[0273] Clause 76: The method of clause 13, wherein input values ​​for T, P1, and P2 are signaled in the video data.

[0308]

[0274] Clause 77: The method described in clause 13, wherein T=4, P2=2 and P1=1.

[0309]

[0275] Clause 78: A method as described in clause 12, wherein deriving a Rice parameter scaling value comprises calculating an aggregated history counter value representing an aggregation of history counters, including history counters for all color components including color components of the video data, and deriving the Rice parameter scaling value using the aggregated history counter value.

[0310]

[0276] Clause 79: The method of clause 17, wherein calculating the aggregated history counter value comprises calculating ((StatCoeff[0]*w0)+StatCoeff[1]*w1+StatCoeff[2]*w2) / (w1+w2+w3), wherein StatCoeff[0] represents a first history counter of the history counters for a first color component among the color components, StatCoeff[1] represents a second history counter of the history counters for a second color component among the color components, StatCoeff[2] represents a third history counter of the history counters for a third color component among the color components, and w1, w2, and w3 represent respective weighting values.

[0311]

[0277] Clause 80: The method described in Clause 18, wherein deriving a Rice parameter scaling value comprises deriving a Rice parameter scaling value using (StatCoefAverage≧T)?P2:P1, where StatCoefAverage represents aggregated historical counter values, and T, P1, and P2 represent input values.

[0312]

[0278] Clause 81: The method of clause 19, wherein input values ​​for T, P1, and P2 are predetermined.

[0313]

[0279] Clause 82: The method of clause 19, wherein input values ​​for T, P1, and P2 are signaled in the video data.

[0314]

[0280] Clause 83: The method described in Clause 19, wherein T=4, P2=2 and P1=1.

[0315]

[0281] Clause 84: The method described in clause 19, wherein w0=2, w1=1, and w2=1.

[0316]

[0282] Clause 85: The method of clause 12, wherein the second block comprises one of a coding tree unit (CTU), a transform unit (TU), or a sub-transform unit (sub-TU).

[0317]

[0283] Clause 86: The method of clause 62, wherein, to code the current coefficient, the one or more processors are configured to decode the current coefficient using a normalized value for the sum of absolute values.

[0318]

[0284] Clause 87: The method of clause 62, wherein to code the current coefficient, the one or more processors are configured to encode the current coefficient using a normalized value for the sum of absolute values.

[0319]

[0285] Clause 88: A device for coding video data, the device comprising: a memory configured to store the video data; and one or more processors implemented in a circuit, the one or more processors configured to: calculate a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculate a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculate a normalized value for the sum of absolute values ​​using the base level offset value; and code the current coefficient using the normalized value for the sum of absolute values.

[0320]

[0286] Clause 89: The device of clause 27, wherein the plurality of adjacent coefficients includes five adjacent coefficients to the current coefficient.

[0321]

[0287] Clause 90: The device described in clause 27, wherein the plurality of adjacent coefficients includes two right adjacent coefficients to the current coefficient, two below adjacent coefficients to the current coefficient, and one below-left adjacent coefficient to the current coefficient.

[0322]

[0288] Clause 91: The device described in Clause 27, wherein to calculate the base level offset value, one or more processors are configured to calculate baseLevelOffset=(bitDepth>T)?(isIntra()?P1:P2):(isIntra()?P3:P4), where bitDepth comprises a bit depth for the video data, isIntra() returns a true value if the slice type for the slice is an intra-predicted slice or a false value if the slice type for the slice is an inter-predicted slice, and T, P1, P2, P3, and P4 comprise respective input values.

[0323]

[0289] Clause 92: A device as described in clause 30, wherein T=12.

[0324]

[0290] Clause 93: The device of clause 30, wherein input values ​​for T, P1, P2, P3, and P4 are predetermined.

[0325]

[0291] Clause 94: A device as described in Clause 27, wherein to calculate a normalized value for the sum of absolute values, one or more processors are configured to calculate Clip3(0, 31, locSumAbs-baseLevelOffset), where locSumAbs comprises the sum of absolute values ​​and baseLevelOffset comprises the base level offset value.

[0326]

[0292] Clause 95: A device as described in Clause 27, wherein, to code a current coefficient using a normalized value for the sum of absolute values, one or more processors are configured to determine a Rice parameter corresponding to the normalized value for the sum of absolute values, and to binarize the value for the current coefficient using the Rice parameter to form a binarized value.

[0327]

[0293] Clause 96: The device of clause 27, wherein the current block comprises a first block, the color component of the video data comprises a first block, the sum of the absolute values ​​comprises a first sum of absolute values, and the plurality of adjacent coefficients comprises a first plurality of adjacent coefficients, wherein the one or more processors are further configured to: maintain a history counter representing a history of Rice parameters used to code coefficients of the color component of the video data; derive a Rice parameter scaling value for a second block of the color component of the video data from a current value for the history counter without explicitly coding a value for the Rice parameter scaling value; calculate a second sum of the absolute values ​​of the second plurality of adjacent coefficients for a second coefficient of the second block; calculate a scaled value for the second sum of absolute values ​​using the Rice parameter scaling value; and code the second coefficient of the second block using the scaled value for the second sum of absolute values.

[0328]

[0294] Clause 97: A device as described in Clause 35, wherein to derive a Rice parameter scaling value, one or more processors are configured to calculate (StatCoeff[idx]≧T)?P2:P1, where idx represents a color component, StatCoeff[idx] represents a current value for a history counter, and T, P1, and P2 represent input values.

[0329]

[0295] Clause 98: A device as described in Clause 27, wherein, to code the current coefficient, one or more processors are configured to perform at least one of encoding the current coefficient using a normalized value for the sum of absolute values ​​or decoding the current coefficient using a normalized value for the sum of absolute values.

[0330]

[0296] Clause 99: The device of clause 27, further comprising a display configured to display the decoded video data.

[0331]

[0297] Clause 100: The device of clause 27, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0332]

[0298] Clause 101: A computer-readable storage medium storing instructions that, when executed, cause a processor of a device for coding video data to calculate a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of video data, calculate a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block, calculate a normalized value for the sum of absolute values ​​using the base level offset value, and code the current coefficient using the normalized value for the sum of absolute values.

[0333]

[0299] Clause 102: A device for coding video data, comprising: means for calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; means for calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; means for calculating a normalized value for the sum of absolute values ​​using the base level offset value; and means for coding the current coefficient using the normalized value for the sum of absolute values.

[0334]

[0300] Clause 103: A method for coding video data, the method comprising: calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculating a normalized value for the sum of absolute values ​​using the base level offset value; and coding the current coefficient using the normalized value for the sum of absolute values.

[0335]

[0301] Clause 104: The method of clause 103, wherein the plurality of neighboring coefficients includes five neighboring coefficients to the current coefficient.

[0336]

[0302] Clause 105: A method according to any of clauses 103 and 104, wherein the plurality of adjacent coefficients includes two right adjacent coefficients to the current coefficient, two below adjacent coefficients to the current coefficient, and one below-left adjacent coefficient to the current coefficient.

[0337]

[0303] Clause 106: A method according to any of clauses 103 to 105, wherein calculating the base level offset value comprises calculating baseLevelOffset=(bitDepth>T)?(isIntra()?P1:P2):(isIntra()?P3:P4), where bitDepth comprises a bit depth for the video data, isIntra() returns a true value if the slice type for the slice is an intra-predicted slice or a false value if the slice type for the slice is an inter-predicted slice, and T, P1, P2, P3, and P4 comprise respective input values.

[0338]

[0304] Clause 107: The method of clause 106, wherein T=12.

[0339]

[0305] Clause 108: The method described in clause 107, wherein P1=5, P2=10, P3=6, and P4=20.

[0340]

[0306] Clause 109: The method described in clause 107, wherein P1=5, P2=10, P3=10, and P4=20.

[0341]

[0307] Clause 110: The method of any of clauses 106 to 109, wherein input values ​​for T, P1, P2, P3, and P4 are predetermined.

[0342]

[0308] Clause 111: A method according to any of clauses 106 to 109, wherein input values ​​for T, P1, P2, P3, and P4 are signaled in the bitstream.

[0343]

[0309] Clause 112: A method according to any of clauses 103 to 111, wherein calculating a normalized value for the sum of absolute values ​​comprises calculating Clip3(0, 31, locSumAbs-baseLevelOffset), where locSumAbs comprises the sum of absolute values ​​and baseLevelOffset comprises the base level offset value.

[0344]

[0310] Clause 113: A method described in any of clauses 103 to 112, wherein coding the current coefficient using a normalized value for the sum of absolute values ​​comprises determining a Rice parameter corresponding to the normalized value for the sum of absolute values, and binarizing the value for the current coefficient using the Rice parameter to form a binarized value.

[0345]

[0311] Clause 114: A method according to any of clauses 103 to 113, wherein the current block comprises a first block, the color component of the video data comprises a first block, the sum of the absolute values ​​comprises a first sum of absolute values, and the plurality of adjacent coefficients comprises a first plurality of adjacent coefficients, and the method further comprises maintaining a history counter representing a history of Rice parameters used to code coefficients of the color component of the video data, deriving a Rice parameter scaling value for a second block of the color component of the video data from a current value for the history counter without explicitly coding a value for the Rice parameter scaling value, calculating a second sum of absolute values ​​of the second plurality of adjacent coefficients for a second coefficient of the second block, calculating a scaled value for the second sum of absolute values ​​using the Rice parameter scaling value, and coding a second coefficient of the second block using the scaled value for the second sum of absolute values.

[0346]

[0312] Clause 115: A method as described in clause 114, wherein deriving the Rice parameter scaling value comprises calculating (StatCoeff[idx]≧T)?P2:P1, where idx represents a color component, StatCoeff[idx] represents a current value for a history counter, and T, P1, and P2 represent input values.

[0347]

[0313] Clause 116: The method of clause 115, wherein input values ​​for T, P1, and P2 are predetermined.

[0348]

[0314] Clause 117: The method of clause 115, wherein the input values ​​for T, P1, and P2 are signaled in the video data.

[0349]

[0315] Clause 118: A method according to any one of clauses 115 to 117, wherein T=4, P2=2 and P1=1.

[0350]

[0316] Clause 119: A method according to any of clauses 114 to 118, wherein deriving the Rice parameter scaling value comprises calculating an aggregated history counter value representing an aggregation of history counters, including history counters for all color components including color components of the video data, and deriving the Rice parameter scaling value using the aggregated history counter value.

[0351]

[0317] Clause 120: The method of clause 119, wherein calculating the aggregated history counter value comprises calculating ((StatCoeff[0]*w0)+StatCoeff[1]*w1+StatCoeff[2]*w2) / (w1+w2+w3), where StatCoeff[0] represents a first history counter of the history counters for a first color component of the color components, StatCoeff[1] represents a second history counter of the history counters for a second color component of the color components, StatCoeff[2] represents a third history counter of the history counters for a third color component of the color components, and w1, w2, and w3 represent respective weighting values.

[0352]

[0318] Clause 121: The method described in clause 120, wherein deriving a Rice parameter scaling value comprises deriving a Rice parameter scaling value using (StatCoefAverage≧T)?P2:P1, where StatCoefAverage represents aggregated historical counter values, and T, P1, and P2 represent input values.

[0353]

[0319] Clause 122: The method of clause 121, wherein input values ​​for T, P1, and P2 are predetermined.

[0354]

[0320] Clause 123: The method of clause 121, wherein the input values ​​for T, P1, and P2 are signaled in the video data.

[0355]

[0321] Clause 124: A method according to any one of clauses 121 to 123, wherein T=4, P2=2 and P1=1.

[0356]

[0322] Clause 125: A method according to any one of clauses 121 to 124, wherein w0=2, w1=1, and w2=1.

[0357]

[0323] Clause 126: The method of any of clauses 114 to 125, wherein the second block comprises one of a coding tree unit (CTU), a transform unit (TU), or a sub-transform unit (sub-TU).

[0358]

[0324] Clause 127: A method according to any of clauses 103 to 126, wherein to code the current coefficient, one or more processors are configured to decode the current coefficient using a normalized value for the sum of absolute values.

[0359]

[0325] Clause 128: A method according to any of clauses 103 to 127, wherein, to code the current coefficient, one or more processors are configured to encode the current coefficient using a normalized value for the sum of absolute values.

[0360]

[0326] Clause 129: A device for coding video data, the device comprising: a memory configured to store the video data; and one or more processors implemented in a circuit, the one or more processors configured to: calculate a sum of absolute values ​​of a plurality of adjacent coefficients to a current coefficient for a current block of the video data; calculate a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; calculate a normalized value for the sum of absolute values ​​using the base level offset value; and code the current coefficient using the normalized value for the sum of absolute values.

[0361]

[0327] Clause 130: The device of clause 129, wherein the plurality of adjacent coefficients includes five adjacent coefficients to the current coefficient.

[0362]

[0328] Clause 131: A device described in either of clauses 129 and 130, wherein the plurality of adjacent coefficients includes two right adjacent coefficients to the current coefficient, two below adjacent coefficients to the current coefficient, and one below-left adjacent coefficient to the current coefficient.

[0363]

[0329] Clause 132: A device described in any of clauses 129 to 131, wherein to calculate the base level offset value, one or more processors are configured to calculate baseLevelOffset=(bitDepth>T)?(isIntra()?P1:P2):(isIntra()?P3:P4), where bitDepth has a bit depth for the video data, isIntra() returns a true value if the slice type for the slice is an intra-predicted slice or a false value if the slice type for the slice is an inter-predicted slice, and T, P1, P2, P3, and P4 have their respective input values.

[0364]

[0330] Clause 133: A device according to clause 132, wherein T=12.

[0365]

[0331] Clause 134: A device described in any of clauses 132 and 133, wherein input values ​​for T, P1, P2, P3, and P4 are predetermined.

[0366]

[0332] Clause 135: A device described in any of clauses 129 to 134, wherein to calculate a normalized value for the sum of absolute values, one or more processors are configured to calculate Clip3(0, 31, locSumAbs-baseLevelOffset), where locSumAbs comprises the sum of absolute values ​​and baseLevelOffset comprises the base level offset value.

[0367]

[0333] Clause 136: A device as described in Clause 135, wherein, to code a current coefficient using a normalized value for the sum of absolute values, one or more processors are configured to determine a Rice parameter corresponding to the normalized value for the sum of absolute values, and to binarize the value for the current coefficient using the Rice parameter to form a binarized value.

[0368]

[0334] Clause 137: A device described in any of clauses 129 to 136, wherein the current block comprises a first block, the color component of the video data comprises a first block, the sum of the absolute values ​​comprises a first sum of absolute values, and the plurality of adjacent coefficients comprises a first plurality of adjacent coefficients, wherein the one or more processors are further configured to: maintain a history counter representing a history of Rice parameters used to code coefficients of the color component of the video data; derive a Rice parameter scaling value for a second block of the color component of the video data from a current value for the history counter without explicitly coding a value for the Rice parameter scaling value; calculate a second sum of the absolute values ​​of the second plurality of adjacent coefficients for a second coefficient of the second block; calculate a scaled value for the second sum of absolute values ​​using the Rice parameter scaling value; and code the second coefficient of the second block using the scaled value for the second sum of absolute values.

[0369]

[0335] Clause 138: A device as described in clause 137, wherein to derive a Rice parameter scaling value, one or more processors are configured to calculate (StatCoeff[idx]≧T)?P2:P1, where idx represents a color component, StatCoeff[idx] represents a current value for a history counter, and T, P1, and P2 represent input values.

[0370]

[0336] Clause 139: A device described in any of clauses 129 to 138, wherein, to code the current coefficient, one or more processors are configured to perform at least one of encoding the current coefficient using a normalized value for the sum of absolute values ​​or decoding the current coefficient using a normalized value for the sum of absolute values.

[0371]

[0337] Clause 140: A device described in any of clauses 129 to 139, further comprising a display configured to display the decoded video data.

[0372]

[0338] Clause 141: A device described in any of clauses 129 to 140, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0373]

[0339] Clause 142: A computer-readable storage medium storing instructions that, when executed, cause a processor of a device for coding video data to calculate a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of video data, calculate a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block, calculate a normalized value for the sum of absolute values ​​using the base level offset value, and code the current coefficient using the normalized value for the sum of absolute values.

[0374]

[0340] Clause 143: A device for coding video data, comprising: means for calculating a sum of absolute values ​​of a plurality of adjacent coefficients relative to a current coefficient for a current block of the video data; means for calculating a base level offset value according to at least one of a bit depth for the video data or a slice type for a slice including the current block; means for calculating a normalized value for the sum of absolute values ​​using the base level offset value; and means for coding the current coefficient using the normalized value for the sum of absolute values.

[0375]

[0341] In accordance with the above examples, it should be recognized that some acts or events of any of the techniques described herein may be performed in a different sequence, added, merged, or entirely excluded (e.g., not all described acts or events may be required to practice the techniques). Moreover, in some examples, acts or events may be performed simultaneously rather than sequentially, for example, through multithreaded processing, interrupt processing, or multiple processors.

[0376] In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which correspond to tangible media such as data storage media, or communication media, including any medium that facilitates transfer of a computer program from one place to another, for example, according to a communications protocol. In this manner, computer-readable media may generally correspond to (1) tangible computer-readable storage media that is non-transitory, or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, code, and / or data structures for implementing the techniques described in this disclosure. A computer program product may include computer-readable media.

[0377]

[0343] By way of example, and not limitation, such computer-readable storage media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but instead cover non-transitory, tangible storage media. As used herein, disk and disc include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs reproduce data optically with a laser. Combinations of the above should also be included within the scope of computer-readable media.

[0378]

[0344] The instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the terms "processor" and "processing circuitry," as used herein, may refer to any of the above structures or any other structure suitable for implementing the techniques described herein. Furthermore, in some aspects, the functionality described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into a combined codec. Also, the techniques may be fully implemented in one or more circuits or logic elements.

[0379] The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including wireless handsets, integrated circuits (ICs), or sets of ICs (e.g., chipsets). Although various components, modules, or units have been described in this disclosure to highlight functional aspects of devices configured to implement the disclosed techniques, those components, modules, or units do not necessarily require realization by different hardware units. Rather, as described above, the various units may be combined in a codec hardware unit or provided by a collection of interoperable hardware units, including one or more processors described above, along with suitable software and / or firmware.

[0380]

[0346] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. 1. A method for coding video data, comprising: calculating a sum of absolute values ​​of a plurality of adjacent coefficients for a current coefficient for a current block of video data; calculating a base level offset value according to a bit depth for the video data and a slice type for a slice including the current block, where the slice type indicates whether the slice is intra-predictive coded or inter-predictive coded. normalizing the sum of absolute values ​​using the base level offset value; determining a Rice parameter based on the normalized value of the absolute value; coding the current coefficient using the Rice parameters; A method comprising:

2. 2. The method of claim 1, wherein the plurality of neighboring coefficients includes five neighboring coefficients to the current coefficient, and preferably the plurality of neighboring coefficients includes two right neighboring coefficients to the current coefficient, two below neighboring coefficients to the current coefficient, and one below-left neighboring coefficient to the current coefficient.

3. Calculating the base level offset value comprises calculating baseLevelOffset=(bitDepth>T)?(isIntra()?P1:P2):(isIntra()?P3:P4); where baseLevelOffset is the base level offset value, bitDepth comprises the bit depth for the video data, isIntra() returns a value of true if the slice type for the slice is an intra predicted slice or a value of false if the slice type for the slice is an inter predicted slice, T, P1, P2, P3, and P4 comprise respective input values, and a question mark operator in an equation of the form condition?X:Y returns a value of X if a condition is true and a value of Y if a condition is false. The method of claim 1.

4. 4. The method of claim 3, wherein T=12.

5. 5. The method of claim 4, wherein P1=5, P2=10, P3=6, and P4=20, or P1=5, P2=10, P3=10, and P4=20.

6. 4. The method of claim 3, wherein the input values ​​for T, P1, P2, P3, and P4 are predetermined or the input values ​​for T, P1, P2, P3, and P4 are signaled in a bitstream.

7. 2. The method of claim 1 , wherein calculating the normalized value for the sum of absolute values ​​comprises calculating Clip3(0, 31, locSumAbs-baseLevelOffset), where locSumAbs comprises the sum of absolute values ​​and baseLevelOffset comprises the base level offset value.

8. 2. The method of claim 1 , wherein coding the current coefficient using the normalized value for the sum of absolute values ​​further comprises binarizing a value for the current coefficient using the Rice parameter to form a binarized value.

9. the current block comprises a first block, a color component of the video data comprises the first block, the sum of absolute values ​​comprises a first sum of absolute values, and the plurality of neighboring coefficients comprises a first plurality of neighboring coefficients, the method comprising: maintaining a history counter representing a history of Rice parameters used to code coefficients of the color components of the video data; deriving a Rice parameter scaling value for the second block of the color components of the video data from a current value for the history counter without explicitly coding a value for the Rice parameter scaling value; calculating a second sum of absolute values ​​of a second plurality of adjacent coefficients to a second coefficient of the second block; calculating a scaled value for the second sum of absolute values ​​using the Rice parameter scaling value; coding the second coefficient of the second block using the scaled value for the second sum of absolute values; and The method of claim 1 further comprising:

10. Deriving the Rice parameter scaling value comprises calculating (StatCoeff[idx]≧T)? P2:P1; where idx represents the color components, StatCoeff[idx] represents the current value for the history counter, and T, P1, and P2 represent input values; wherein the input values ​​for T, P1, and P2 are predetermined or the input values ​​for T, P1, and P2 are signaled in the video data.

10. The method of claim 9.

11. Deriving the Rice parameter scaling value comprises: calculating an aggregated history counter value representing an aggregation of history counters including the history counters for all color components comprising the color component of the video data, wherein calculating the aggregated history counter value preferably comprises calculating ((StatCoeff[0]*w0)+StatCoeff[1]*w1+StatCoeff[2]*w2) / (w1+w2+w3), wherein StatCoeff[0] represents a first one of the history counters for a first one of the color components, StatCoeff[1] represents a second one of the history counters for a second one of the color components, StatCoeff[2] represents a third one of the history counters for a third one of the color components, and w1, w2, and w3 represent respective weighting values. deriving the Rice parameter scaling value using the aggregated history counter values, wherein deriving the Rice parameter scaling value preferably comprises deriving the Rice parameter scaling value using (StatCoefAverage >= T)? P2:P1, where StatCoefAverage represents the aggregated history counter values, and T, P1, and P2 represent input values. The method of claim 9 comprising:

12. 2. The method of claim 1, wherein coding the current coefficient comprises decoding the current coefficient using the normalized value for the sum of absolute values, or wherein coding the current coefficient comprises encoding the current coefficient using the normalized value for the sum of absolute values.

13. 1. A device for coding video data, comprising: a memory configured to store video data; one or more processors implemented in circuitry; wherein the one or more processors: calculating a sum of absolute values ​​of a plurality of adjacent coefficients for a current coefficient for a current block of video data; calculating a base level offset value according to a bit depth for the video data and a slice type for a slice including the current block, where the slice type indicates whether the slice is intra-predictive coded or inter-predictive coded. normalizing the sum of absolute values ​​using the base level offset value; determining a Rice parameter based on the normalized value of the absolute value; coding the current coefficient using the Rice parameters; A device configured to:

14. The device of claim 13, wherein the processor is configured to execute a method according to any one of claims 2 to 12.

15. The device of claim 13 or 14, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

Images