Signaling partition aspect ratio constraints for image and video coding

Abstract

Decoding using partition aspect ratio constraints includes accessing block partition aspect ratio constraint data indicating a maximum block partition elongation and obtaining reconstructed block data. Obtaining the reconstructed block data includes obtaining a sequence of block partition symbols for the current block and partitioning the current block in accordance with the sequence of block partition symbols. Obtaining the sequence of block partition symbols includes in response to determining that partitioning the current block in accordance with a first available value of a current symbol from the sequence of block partition symbols corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as a value of the current symbol, a second available value of the current symbol, wherein data indicating the value of the current symbol is absent from the encoded bitstream.

Description

Atty. Doc. No. GOGL-2305-A-WOSIGNALING PARTITION ASPECT RATIO CONSTRAINTS FOR IMAGE AND VIDEO CODINGCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to and the benefit of U.S. Provisional Application Serial No. 63 / 776,738, filed March 24, 2025, the entire disclosure of which is hereby incorporated by reference.BACKGROUND

[0002] Digital images and video can be used, for example, on the internet, for remote business meetings via video conferencing, high-definition video entertainment, video advertisements, or sharing of user-generated content. Due to the large amount of data involved in transferring and processing image and video data, high-performance compression may be advantageous for transmission and storage. Accordingly, it would be advantageous to provide high-resolution image and video transmitted over communications channels having limited bandwidth.SUMMARY

[0003] This application relates to encoding and decoding of image data, video stream data, or both for transmission, storage, or both. Disclosed herein are aspects of systems, methods, and apparatuses for encoding and decoding using partition aspect ratio constraints.

[0004] Variations in these and other aspects will be described in additional detail hereafter.

[0005] An aspect is a method for decoding using partition aspect ratio constraints.Decoding using partition aspect ratio constraints includes accessing, from an encoded bitstream, block partition aspect ratio constraint data indicating a maximum block partition elongation, obtaining reconstructed block data for a current block of a current frame of a sequence of frames, including the reconstructed block data in reconstructed frame data for the current frame, and outputting the reconstructed frame data. Obtaining the reconstructed block data may include obtaining a sequence of block partition symbols for the current block and partitioning the current block in accordance with the sequence of block partition symbols. Obtaining the sequence of block partition symbols may include, in response to determiningthat partitioning the current block in accordance with a first available value of a current symbol from the sequence of block partition symbols corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as a value of the current symbol, a second available value of the current symbol, wherein data indicating the value of the current symbol is absent from the encoded bitstream.

[0006] An aspect is an apparatus comprising a non-transitory computer-readable medium and a processor configured to execute instructions stored on the non-transitory computer-readable medium to access, from an encoded bitstream, block partition aspect ratio constraint data indicating a maximum block partition elongation, obtain reconstructed block data for a current block of a current frame of a sequence of frames, include the reconstructed block data in reconstructed frame data for the current frame, and output the reconstructed frame data. To obtain the reconstructed block data, the processor is configured to execute the instructions to obtain a sequence of block partition symbols for the current block and partition the current block in accordance with the sequence of block partition symbols. To obtain the sequence of block partition symbols, the processor is configured to execute the instructions to, in response to a determination that partitioning the current block in accordance with a first available value of a current symbol from the sequence of block partition symbols corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtain, as a value of the current symbol, a second available value of the current symbol, wherein data indicating the value of the current symbol is absent from the encoded bitstream.

[0007] An aspect is a method for encoding using partition aspect ratio constraints.Encoding using partition aspect ratio constraints includes generating an encoded bitstream by encoding an input video and outputting the encoded bitstream. Encoding the input video comprises including, in the encoded bitstream, block partition aspect ratio constraint data indicating a maximum block partition elongation and encoding a current block from a current frame from the input video. Encoding the current block includes obtaining a sequence of block partition symbols for the current block, wherein obtaining the sequence of block partition symbols includes obtaining a value of a current symbol from the sequence of block partition symbols, wherein the value of the current symbol is a first available value of the current symbol, and, on a condition that partitioning the current block in accordance with a second available value of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation, omitting including data indicating the value of the current symbol in the encoded bitstream.

[0008] An aspect is an apparatus comprising a non-transitory computer-readable medium and a processor configured to execute instructions stored on the non-transitory computer-readable medium to perform encoding using partition aspect ratio constraints.

[0009] An aspect is a non-transitory computer-readable medium having stored thereon an encoded bitstream, the encoded bitstream comprising encoded block partition aspect ratio constraint data indicating a maximum block partition elongation and encoded data for a current block of a current frame. The encoded data includes an encoded value of a sequentially first symbol from a sequence of block partition symbols, wherein the current block is partitioned in accordance with the sequence of block partition symbols, and wherein the encoded value indicates partitioning of the current block, wherein data encoding a value of a second symbol from the sequence of block partition symbols is absent from the encoded bitstream.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views unless otherwise noted or otherwise clear from context.

[0011] FIG. 1 is a diagram of a computing device in accordance with implementations of this disclosure.

[0012] FIG. 2 is a diagram of a computing and communications system in accordance with implementations of this disclosure.

[0013] FIG. 3 is a diagram of a video stream for use in encoding and decoding in accordance with implementations of this disclosure.

[0014] FIG. 4 is a block diagram of an encoder in accordance with implementations of this disclosure.

[0015] FIG. 5 is a block diagram of a decoder in accordance with implementations of this disclosure.

[0016] FIG. 6 is a block diagram of a representation of a portion of a frame in accordance with implementations of this disclosure.

[0017] FIG. 7 is a block diagram of an example of available partition types.

[0018] FIG. 8 is a flowchart diagram of an example of obtaining block partition symbols.

[0019] FIG. 9 is a flowchart diagram of an example of decoding using partition aspect ratio constraints in accordance with implementations of this disclosure.

[0020] FIG. 10 is a flowchart diagram of an example of encoding using partition aspect ratio constraints in accordance with implementations of this disclosure.DETAILED DESCRIPTION

[0021] Image and video compression schemes may include breaking an image, or frame, into smaller portions, such as blocks, and generating an output bitstream using techniques to minimize the bandwidth utilization of the information included for each block in the output. In some implementations, the information included for each block in the output may be limited by reducing spatial redundancy, reducing temporal redundancy, or a combination thereof. For example, temporal or spatial redundancies may be reduced by predicting a frame, or a portion thereof, based on information available to both the encoder and decoder, and including information representing a difference, or residual, between the predicted frame and the original frame in the encoded bitstream. The residual information may be further compressed by transforming the residual information into transform coefficients (e.g., energy compaction), quantizing the transform coefficients, and entropy coding the quantized transform coefficients. Other coding information, such as motion information, may be included in the encoded bitstream, which may include transmitting differential information based on predictions of the encoding information, which may be entropy coded to further reduce the corresponding bandwidth utilization. An encoded bitstream can be decoded to reconstruct the blocks and the source images from the limited information. In some implementations, the accuracy, efficiency, or both, of coding a block using either interprediction or intra-prediction may be limited.

[0022] Block-based hybrid video coding techniques, or codecs, may partition a block into subblock partitions in accordance with one or more defined partitioning types and may signal a sequence of block partition symbols or tokens to indicate the partition type for a block.

[0023] The encoding and decoding using partition aspect ratio constraints described herein improves on video coding techniques, or codecs, by signaling a maximum block partition elongation and omitting signaling one or more block partition symbols or tokens that correspond with a block partition elongation that exceeds the maximum block partition elongation.

[0024] FIG. 1 is a diagram of a computing device 100 in accordance with implementations of this disclosure. The computing device 100 shown includes a memory 110, a processor 120, a user interface (UI) 130, an electronic communication unit 140, a sensor 150, a power source 160, and a bus 170. As used herein, the term “computing device”includes any unit, or a combination of units, capable of performing any method, or any portion or portions thereof, disclosed herein.

[0025] The computing device 100 may be a stationary computing device, such as a personal computer (PC), a server, a workstation, a minicomputer, or a mainframe computer; or a mobile computing device, such as a mobile telephone, a personal digital assistant (PDA), a laptop, or a tablet PC. Although shown as a single unit, any one element or elements of the computing device 100 can be integrated into any number of separate physical units. For example, the user interface 130 and processor 120 can be integrated in a first physical unit and the memory 110 can be integrated in a second physical unit.

[0026] The memory 110 (e.g., a non-transitory computer-readable medium) can include any non-transitory computer-usable or non-transitory computer-readable medium, such as any tangible device that can, for example, contain, store, communicate, or transport data 112, instructions 114, an operating system 116, or any information associated therewith, for use by or in connection with other components of the computing device 100. The non-transitory computer-usable or computer-readable medium can be, for example, a solid-state drive, a memory card, removable media, a read-only memory (ROM), a random-access memory (RAM), any type of disk including a hard disk, a floppy disk, an optical disk, a magnetic or optical card, application- specific integrated circuits (ASICs), or any type of non-transitory media suitable for storing electronic information, or any combination thereof.

[0027] Although shown as a single unit, the memory 110 may include multiple physical units, such as one or more primary memory units, such as random-access memory units, one or more secondary data storage units, such as disks, or a combination thereof. For example, the data 112, or a portion thereof, the instructions 114, or a portion thereof, or both, may be stored in a secondary storage unit and may be loaded or otherwise transferred to a primary storage unit in conjunction with processing the respective data 112, executing the respective instructions 114, or both. In some implementations, the memory 110, or a portion thereof, may be removable memory.

[0028] The data 112 can include information, such as input audio data, encoded audio data, decoded audio data, or the like. The instructions 114 can include directions, such as code, for performing any method, or any portion or portions thereof, disclosed herein. The instructions 114 can be realized in hardware, software, or any combination thereof. For example, the instructions 114 may be implemented as information stored in the memory 110, such as a computer program, which may be executed by the processor 120 to perform any of the respective methods, algorithms, aspects, or combinations thereof, as described herein.

[0029] Although shown as included in the memory 110, in some implementations, the instructions 114, or a portion thereof, may be implemented as a special purpose processor, or circuitry, that can include specialized hardware for carrying out any of the methods, algorithms, aspects, or combinations thereof, as described herein. Portions of the instructions 114 can be distributed across multiple processors on the same machine or different machines or across a network such as a local area network, a wide area network, the Internet, or a combination thereof.

[0030] The processor 120 can include any device or system capable of manipulating or processing a digital signal or other electronic information now-existing or hereafter developed, including optical processors, quantum processors, molecular processors, or a combination thereof. For example, the processor 120 can include a special purpose processor, a central processing unit (CPU), a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessor in association with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a programmable logic array, programmable logic controller, microcode, firmware, any type of integrated circuit (IC), a state machine, or any combination thereof. As used herein, the term “processor” includes a single processor or multiple processors.

[0031] The user interface 130 can include any unit capable of interfacing with a user, such as a virtual or physical keypad, a touchpad, a display, a touch display, a speaker, a microphone, a video camera, a sensor, or any combination thereof. For example, the user interface 130 may be an audio-visual display device, and the computing device 100 may present audio, such as decoded audio, using the user interface 130 of the audio-visual display device, such as in conjunction with displaying video, such as decoded video. Although shown as a single unit, the user interface 130 may include one or more physical units. For example, the user interface 130 may include an audio interface for performing audio communication with a user, and a touch display for performing visual and touch-based communication with the user.

[0032] The electronic communication unit 140 can transmit, receive, or transmit and receive signals via a wired or wireless electronic communication medium 180, such as a radio frequency (RF) communication medium, an ultraviolet (UV) communication medium, a visible light communication medium, a fiber optic communication medium, a wireline communication medium, or a combination thereof. For example, as shown, the electronic communication unit 140 is operatively connected to an electronic communication interface 142, such as an antenna, configured to communicate via wireless signals.

[0033] Although the electronic communication interface 142 is shown as a wireless antenna in FIG. 1, the electronic communication interface 142 can be a wireless antenna, as shown, a wired communication port, such as an Ethernet port, an infrared port, a serial port, or any other wired or wireless unit capable of interfacing with a wired or wireless electronic communication medium 180. Although FIG. 1 shows a single electronic communication unit 140 and a single electronic communication interface 142, any number of electronic communication units and any number of electronic communication interfaces can be used.

[0034] The sensor 150 may include, for example, an audio-sensing device, a visible lightsensing device, a motion sensing device, or a combination thereof. For example, the sensor 150 may include a sound-sensing device, such as a microphone, or any other sound-sensing device now existing or hereafter developed that can sense sounds in the proximity of the computing device 100, such as speech or other utterances, made by a user operating the computing device 100. In another example, the sensor 150 may include a camera, or any other image-sensing device now existing or hereafter developed that can sense an image such as the image of a user operating the computing device. Although a single sensor 150 is shown, the computing device 100 may include a number of sensors 150. For example, the computing device 100 may include a first camera oriented with a field of view directed toward a user of the computing device 100 and a second camera oriented with a field of view directed away from the user of the computing device 100.

[0035] The power source 160 can be any suitable device for powering the computing device 100. For example, the power source 160 can include a wired external power source interface; one or more dry cell batteries, such as nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Ei-ion); solar cells; fuel cells; or any other device capable of powering the computing device 100. Although a single power source 160 is shown in FIG. 1, the computing device 100 may include multiple power sources 160, such as a battery and a wired external power source interface.

[0036] Although shown as separate units, the electronic communication unit 140, the electronic communication interface 142, the user interface 130, the power source 160, or portions thereof, may be configured as a combined unit. For example, the electronic communication unit 140, the electronic communication interface 142, the user interface 130, and the power source 160 may be implemented as a communications port capable of interfacing with an external display device, providing communications, power, or both.

[0037] One or more of the memory 110, the processor 120, the user interface 130, the electronic communication unit 140, the sensor 150, or the power source 160, may beoperatively coupled via a bus 170. Although a single bus 170 is shown in FIG. 1, a computing device 100 may include multiple buses. For example, the memory 110, the processor 120, the user interface 130, the electronic communication unit 140, the sensor 150, and the bus 170 may receive power from the power source 160 via the bus 170. In another example, the memory 110, the processor 120, the user interface 130, the electronic communication unit 140, the sensor 150, the power source 160, or a combination thereof, may communicate data, such as by sending and receiving electronic signals, via the bus 170.

[0038] Although not shown separately in FIG. 1, one or more of the processor 120, the user interface 130, the electronic communication unit 140, the sensor 150, or the power source 160 may include internal memory, such as an internal buffer or register. For example, the processor 120 may include internal memory (not shown) and may read data 112 from the memory 110 into the internal memory (not shown) for processing.

[0039] Although shown as separate elements, the memory 110, the processor 120, the user interface 130, the electronic communication unit 140, the sensor 150, the power source 160, and the bus 170, or any combination thereof can be integrated in one or more electronic units, circuits, or chips.

[0040] FIG. 2 is a diagram of a computing and communications system 200 in accordance with implementations of this disclosure. The computing and communications system 200 shown includes computing and communication devices 100 A, 100B, 100C, access points 210A, 210B, and a network 220. For example, the computing and communication system 200 can be a multiple access system that provides communication, such as voice, audio, data, video, messaging, broadcast, or a combination thereof, to one or more wired or wireless communicating devices, such as the computing and communication devices 100A, 100B, 100C. Although, for simplicity, FIG. 2 shows three computing and communication devices 100A, 100B, 100C, two access points 210A, 210B, and one network 220, any number of computing and communication devices, access points, and networks can be used.

[0041] A computing and communication device 100 A, 100B, 100C can be, for example, a computing device, such as the computing device 100 shown in FIG. 1. For example, the computing and communication devices 100 A, 100B may be user devices, such as a mobile computing device, a laptop, a thin client, or a smartphone, and the computing and communication device 100C may be a server, such as a mainframe or a cluster. Although the computing and communication device 100 A and the computing and communication device 100B are described as user devices, and the computing and communication device 100C isdescribed as a server, any computing and communication device may perform some or all of the functions of a server, some, or all, of the functions of a user device, or some or all of the functions of a server and a user device. For example, the server computing and communication device 100C may receive, encode, process, store, transmit, or a combination thereof audio data and one or both of the computing and communication device 100 A and the computing and communication device 100B may receive, decode, process, store, present, or a combination thereof the audio data.

[0042] Each computing and communication device 100 A, 100B, 100C, which may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a cellular telephone, a personal computer, a tablet computer, a server, consumer electronics, or any similar device, can be configured to perform wired or wireless communication, such as via the network 220. For example, the computing and communication devices 100A, 100B, 100C can be configured to transmit or receive wired or wireless communication signals. Although each computing and communication device 100 A, 100B, 100C is shown as a single unit, a computing and communication device can include any number of interconnected elements.

[0043] Each access point 210A, 210B can be any type of device configured to communicate with a computing and communication device 100A, 100B, 100C, a network 220, or both via wired or wireless communication links 180A, 180B, 180C. For example, an access point 210A, 210B can include a base station, a base transceiver station (BTS), a Node-B, an enhanced Node-B (eNode-B), a Home Node-B (HNode-B), a wireless router, a wired router, a hub, a relay, a switch, or any similar wired or wireless device. Although each access point 210A, 210B is shown as a single unit, an access point can include any number of interconnected elements.

[0044] The network 220 can be any type of network configured to provide services, such as voice, data, applications, voice over internet protocol (VoIP), or any other communications protocol or combination of communications protocols, over a wired or wireless communication link. For example, the network 220 can be a local area network (LAN), wide area network (WAN), virtual private network (VPN), a mobile or cellular telephone network, the Internet, or any other means of electronic communication. The network can use a communication protocol, such as the transmission control protocol (TCP), the user datagram protocol (UDP), the internet protocol (IP), the real-time transport protocol (RTP) the HyperText Transport Protocol (HTTP), or a combination thereof.

[0045] The computing and communication devices 100 A, 100B, 100C can communicate with each other via the network 220 using one or more a wired or wireless communicationlinks, or via a combination of wired and wireless communication links. For example, as shown the computing and communication devices 100A, 100B can communicate via wireless communication links 180A, 180B, and computing and communication device 100C can communicate via a wired communication link 180C. Any of the computing and communication devices 100A, 100B, 100C may communicate using any wired or wireless communication link, or links. For example, a first computing and communication device 100 A can communicate via a first access point 210A using a first type of communication link, a second computing and communication device 100B can communicate via a second access point 21 OB using a second type of communication link, and a third computing and communication device 100C can communicate via a third access point (not shown) using a third type of communication link. Similarly, the access points 210A, 21 OB can communicate with the network 220 via one or more types of wired or wireless communication links 230A, 230B. Although FIG. 2 shows the computing and communication devices 100A, 100B, 100C in communication via the network 220, the computing and communication devices 100A, 100B, 100C can communicate with each other via any number of communication links, such as a direct wired or wireless communication link.

[0046] In some implementations, communications between one or more of the computing and communication device 100 A, 100B, 100C may omit communicating via the network 220 and may include transferring data via another medium (not shown), such as a data storage device. For example, the server computing and communication device 100C may store audio data, such as encoded audio data, in a data storage device, such as a portable data storage unit, and one or both of the computing and communication device 100 A or the computing and communication device 100B may access, read, or retrieve the stored audio data from the data storage unit, such as by physically disconnecting the data storage device from the server computing and communication device 100C and physically connecting the data storage device to the computing and communication device 100 A or the computing and communication device 100B.

[0047] Other implementations of the computing and communications system 200 are possible. For example, in an implementation, the network 220 can be an ad-hoc network and can omit one or more of the access points 210A, 210B. The computing and communications system 200 may include devices, units, or elements not shown in FIG. 2. For example, the computing and communications system 200 may include many more communicating devices, networks, and access points.

[0048] FIG. 3 is a diagram of a video stream 300 for use in encoding and decoding in accordance with implementations of this disclosure. A video stream 300, such as a video stream captured by a video camera or a video stream generated by a computing device, may include a video sequence 310. The video sequence 310 may include a sequence of adjacent frames 320. Although three adjacent frames 320 are shown, the video sequence 310 can include any number of adjacent frames 320.

[0049] Each frame 330 from the adjacent frames 320 may represent a single image from the video stream. Although not shown in FIG. 3, a frame 330 may include one or more segments, tiles, or planes, which may be coded, or otherwise processed, independently, such as in parallel. A frame 330 may include one or more tiles 340. Each of the tiles 340 may be a rectangular region of the frame that can be coded independently. Each of the tiles 340 may include respective blocks 350. Although not shown in FIG. 3, a block can include pixels. For example, a block can include a 16x16 group of pixels, an 8x8 group of pixels, an 8x16 group of pixels, or any other group of pixels. Unless otherwise indicated herein, the term ‘block’ can include a superblock, a macroblock, a segment, a slice, or any other portion of a frame. A frame, a block, a pixel, or a combination thereof can include display information, such as luminance information, chrominance information, or any other information that can be used to store, modify, communicate, or display the video stream or a portion thereof.

[0050] FIG. 4 is a block diagram of an encoder 400 in accordance with implementations of this disclosure. Encoder 400 can be implemented in a device, such as the computing device 100 shown in FIG. 1 or the computing and communication devices 100A, 100B, 100C shown in FIG. 2, as, for example, a computer software program stored in a data storage unit, such as the memory 110 shown in FIG. 1. The computer software program can include machine instructions that may be executed by a processor, such as the processor 120 shown in FIG. 1, and may cause the device to encode video data as described herein. The encoder 400 can be implemented as specialized hardware included, for example, in computing device 100.

[0051] The encoder 400 can encode an input video stream 402, such as the video stream 300 shown in FIG. 3, to generate an encoded (compressed) bitstream 404. In some implementations, the encoder 400 may include a forward path for generating the compressed bitstream 404. The forward path may include an intra / inter prediction unit 410, a transform unit 420, a quantization unit 430, an entropy encoding unit 440, or any combination thereof. In some implementations, the encoder 400 may include a reconstruction path (indicated by the broken connection lines) to reconstruct a frame for encoding of further blocks. The reconstruction path may include a dequantization unit 450, an inverse transform unit 460, areconstruction unit 470, a filtering unit 480, or any combination thereof. Other structural variations of the encoder 400 can be used to encode the video stream 402.

[0052] For encoding the video stream 402, each frame within the video stream 402 can be processed in units of blocks. Thus, a current block may be identified from the blocks in a frame, and the current block may be encoded.

[0053] At the intra / inter prediction unit 410, the current block can be encoded using either intra-frame prediction, which may be within a single frame, or inter-frame prediction, which may be from frame to frame. Intra-prediction may include generating a prediction block from samples in the current frame that have been previously encoded and reconstructed. Inter-prediction may include generating a prediction block from samples in one or more previously constructed reference frames. Generating a prediction block for a current block in a current frame may include performing motion estimation to generate a motion vector indicating an appropriate reference portion of the reference frame.

[0054] The intra / inter prediction unit 410 may subtract the prediction block from the current block (raw block) to produce a residual block. The transform unit 420 may perform a block-based transform, which may include transforming the residual block into transform coefficients in, for example, the frequency domain. Examples of block-based transforms include the Karhunen-Loeve Transform (KLT), the Discrete Cosine Transform (DCT), the Singular Value Decomposition Transform (SVD), and the Asymmetric Discrete Sine Transform (ADST). In an example, the DCT may include transforming a block into the frequency domain. The DCT may include using transform coefficient values based on spatial frequency, with the lowest frequency (i.e., direct current (DC)) coefficient at the top-left of the matrix and the highest frequency coefficient at the bottom-right of the matrix.

[0055] The quantization unit 430 may convert the transform coefficients into discrete quantum values, which may be referred to as quantized transform coefficients or quantization levels. The quantized transform coefficients can be entropy encoded by the entropy encoding unit 440 to produce entropy-encoded coefficients. Entropy encoding can include using a probability distribution metric. The entropy-encoded coefficients and information used to decode the block, which may include the type of prediction used, motion vectors, and quantizer values, can be output to the compressed bitstream 404. The compressed bitstream 404 can be formatted using various techniques, such as run-length encoding (RLE) and zerorun coding.

[0056] The reconstruction path can be used to maintain reference frame synchronization between the encoder 400 and a corresponding decoder, such as the decoder 500 shown inFIG. 5. The reconstruction path may be similar to the decoding process discussed below and may include decoding the encoded frame, or a portion thereof, which may include decoding an encoded block, which may include dequantizing the quantized transform coefficients at the dequantization unit 450 and inverse transforming the dequantized transform coefficients at the inverse transform unit 460 to produce a derivative residual block. The reconstruction unit 470 may add the prediction block generated by the intra / inter prediction unit 410 to the derivative residual block to create a decoded block. The filtering unit 480 can be applied to the decoded block to generate a reconstructed block, which may reduce distortion, such as blocking artifacts. Although one filtering unit 480 is shown in FIG. 4, filtering the decoded block may include loop filtering, deblocking filtering, or other types of filtering or combinations of types of filtering. The reconstructed block may be stored or otherwise made accessible as a reconstructed block, which may be a portion of a reference frame, for encoding another portion of the current frame, another frame, or both, as indicated by the broken line at 482. Coding information, such as deblocking threshold index values, for the frame may be encoded, included in the compressed bitstream 404, or both, as indicated by the broken line at 484.

[0057] Other variations of the encoder 400 can be used to encode the compressed bitstream 404. For example, a non-transform-based encoder 400 can quantize the residual block directly without the transform unit 420. In some implementations, the quantization unit 430 and the dequantization unit 450 may be combined into a single unit.

[0058] FIG. 5 is a block diagram of a decoder 500 in accordance with implementations of this disclosure. The decoder 500 can be implemented in a device, such as the computing device 100 shown in FIG. 1 or the computing and communication devices 100A, 100B, 100C shown in FIG. 2, as, for example, a computer software program stored in a data storage unit, such as the memory 110 shown in FIG. 1. The computer software program can include machine instructions that may be executed by a processor, such as the processor 120 shown in FIG. 1, and may cause the device to decode video data as described herein. The decoder 500 can be implemented as specialized hardware included, for example, in computing device 100.

[0059] The decoder 500 may receive a compressed bitstream 502, such as the compressed bitstream 404 shown in FIG. 4, and may decode the compressed bitstream 502 to generate an output video stream 504. The decoder 500 may include an entropy decoding unit 510, a dequantization unit 520, an inverse transform unit 530, an intra / inter prediction unit 540, areconstruction unit 550, a filtering unit 560, or any combination thereof. Other structural variations of the decoder 500 can be used to decode the compressed bitstream 502.

[0060] The entropy decoding unit 510 may decode data elements within the compressed bitstream 502 using, for example, Context Adaptive Binary Arithmetic Decoding, to produce a set of quantized transform coefficients. The dequantization unit 520 can dequantize the quantized transform coefficients, and the inverse transform unit 530 can inverse transform the dequantized transform coefficients to produce a derivative residual block, which may correspond to the derivative residual block generated by the inverse transform unit 460 shown in FIG. 4. Using header information decoded from the compressed bitstream 502, the intra / inter prediction unit 540 may generate a prediction block corresponding to the prediction block created in the encoder 400. At the reconstruction unit 550, the prediction block can be added to the derivative residual block to create a decoded block. The filtering unit 560 can be applied to the decoded block to reduce artifacts, such as blocking artifacts, which may include loop filtering, deblocking filtering, or other types of filtering or combinations of types of filtering, and which may include generating a reconstructed block, which may be output as the output video stream 504.

[0061] Other variations of the decoder 500 can be used to decode the compressed bitstream 502. For example, the decoder 500 can produce the output video stream 504 without the deblocking filtering unit 560.

[0062] FIG. 6 is a block diagram of a representation of a portion 600 of a frame, such as the frame 330 shown in FIG. 3, in accordance with implementations of this disclosure. As shown, the portion 600 of the frame includes four 64x64 blocks 610, in two rows and two columns in a matrix or Cartesian plane. In some implementations, a 64x64 block may be a maximum coding unit, N=64. Each 64x64 block may include four 32x32 blocks 620. Each 32x32 block may include four 16x16 blocks 630. Each 16x16 block may include four 8x8 blocks 640. Each 8x8 block 640 may include four 4x4 blocks 650. Each 4x4 block 650 may include 16 pixels, which may be represented in four rows and four columns in each respective block in the Cartesian plane or matrix. The pixels may include information representing an image captured in the frame, such as luminance information, color information, and location information. In some implementations, a block, such as a 16x16 pixel block as shown, may include a luminance block 660, which may include luminance pixels 662; and two chrominance blocks 670, 680, such as a U or Cb chrominance block 670, and a V or Cr chrominance block 680. The chrominance blocks 670, 680 may include chrominance pixels 690. For example, the luminance block 660 may include 16x16 luminance pixels 662 andeach chrominance block 670, 680 may include 8x8 chrominance pixels 690 as shown.Although one arrangement of blocks is shown, any arrangement may be used. Although FIG.6 shows NxN blocks, in some implementations, NxM blocks may be used. For example, 32x64 blocks, 64x32 blocks, 16x32 blocks, 32x16 blocks, or any other size blocks may be used. In some implementations, Nx2N blocks, 2NxN blocks, or a combination thereof may be used.

[0063] In some implementations, video coding may include ordered block-level coding. Ordered block-level coding may include coding blocks of a frame in an order, such as rasterscan order, wherein blocks may be identified and processed starting with a block in the upper left comer of the frame, or portion of the frame, and proceeding along rows from left to right and from the top row to the bottom row, identifying each block in turn for processing. For example, the 64x64 block in the top row and left column of a frame may be the first block coded and the 64x64 block immediately to the right of the first block may be the second block coded. The second row from the top may be the second row coded, such that the 64x64 block in the left column of the second row may be coded after the 64x64 block in the rightmost column of the first row.

[0064] In some implementations, coding a block may include using quad-tree coding, which may include coding smaller block units within a block in raster-scan order. For example, the 64x64 block shown in the bottom left comer of the portion of the frame shown in FIG. 6, may be coded using quad-tree coding wherein the top left 32x32 block may be coded, then the top right 32x32 block may be coded, then the bottom left 32x32 block may be coded, and then the bottom right 32x32 block may be coded. Each 32x32 block may be coded using quad-tree coding wherein the top left 16x16 block may be coded, then the top right 16x16 block may be coded, then the bottom left 16x16 block may be coded, and then the bottom right 16x16 block may be coded. Each 16x16 block may be coded using quad-tree coding wherein the top left 8x8 block may be coded, then the top right 8x8 block may be coded, then the bottom left 8x8 block may be coded, and then the bottom right 8x8 block may be coded. Each 8x8 block may be coded using quad-tree coding wherein the top left 4x4 block may be coded, then the top right 4x4 block may be coded, then the bottom left 4x4 block may be coded, and then the bottom right 4x4 block may be coded. In some implementations, 8x8 blocks may be omitted for a 16x16 block, and the 16x16 block may be coded using quad-tree coding wherein the top left 4x4 block may be coded, then the other 4x4 blocks in the 16x16 block may be coded in raster- scan order.

[0065] In some implementations, video coding may include compressing the information included in an original, or input, frame by, for example, omitting some of the information in the original frame from a corresponding encoded frame. For example, coding may include reducing spectral redundancy, reducing spatial redundancy, reducing temporal redundancy, or a combination thereof.

[0066] In some implementations, reducing spectral redundancy may include using a color model based on a luminance component (Y) and two chrominance components (U and V or Cb and Cr), which may be referred to as the YUV or YCbCr color model, or color space. Using the YUV color model may include using a relatively large amount of information to represent the luminance component of a portion of a frame and using a relatively small amount of information to represent each corresponding chrominance component for the portion of the frame. For example, a portion of a frame may be represented by a high-resolution luminance component, which may include a 16x16 block of pixels, and by two lower resolution chrominance components, each of which represents the portion of the frame as an 8x8 block of pixels. A pixel may indicate a value, for example, a value in the range from 0 to 255, and may be stored or transmitted using, for example, eight bits. Although this disclosure is described in reference to the YUV color model, any color model may be used.

[0067] In some implementations, reducing spatial redundancy may include transforming a block into the frequency domain using, for example, a discrete cosine transform (DCT). For example, a unit of an encoder, such as the transform unit 420 shown in FIG. 4, may perform a DCT using transform coefficient values based on spatial frequency.

[0068] In some implementations, reducing temporal redundancy may include using similarities between frames to encode a frame using a relatively small amount of data based on one or more reference frames, which may be previously encoded, decoded, and reconstructed frames of the video stream. For example, a block or pixel of a current frame may be similar to a spatially corresponding block or pixel of a reference frame. In some implementations, a block or pixel of a current frame may be similar to block or pixel of a reference frame at a different spatial location and reducing temporal redundancy may include generating motion information indicating the spatial difference, or translation, between the location of the block or pixel in the current frame and corresponding location of the block or pixel in the reference frame.

[0069] In some implementations, reducing temporal redundancy may include identifying a portion of a reference frame that corresponds to a current block or pixel of a current frame. For example, a reference frame, or a portion of a reference frame, which may be stored inmemory, may be searched to identify a portion for generating a prediction to use for encoding a current block or pixel of the current frame with maximal efficiency. For example, the search may identify a portion of the reference frame for which the difference in pixel values between the current block and a prediction block generated based on the portion of the reference frame is minimized and may be referred to as motion searching. In some implementations, the portion of the reference frame searched may be limited. For example, the portion of the reference frame searched, which may be referred to as the search area, may include a limited number of rows of the reference frame. In an example, identifying the portion of the reference frame for generating a prediction may include calculating a cost function, such as a sum of absolute differences (SAD), between the pixels of portions of the search area and the pixels of the current block.

[0070] In some implementations, the spatial difference between the location of the portion of the reference frame for generating a prediction in the reference frame and the current block in the current frame may be represented as a motion vector. The difference in pixel values between the prediction block and the current block may be referred to as differential data, residual data, a prediction error, or as a residual block. In some implementations, generating motion vectors may be referred to as motion estimation, and a pixel of a current block may be indicated based on location using Cartesian coordinates as / x,y. Similarly, a pixel of the search area of the reference frame may be indicated based on location using Cartesian coordinates as rx, y. A motion vector (MV) for the current block may be determined based on, for example, a SAD between the pixels of the current frame and the corresponding pixels of the reference frame.

[0071] Although described herein with reference to matrix or Cartesian representation of a frame for clarity, a frame may be stored, transmitted, processed, or any combination thereof, in any data structure such that pixel values may be efficiently represented for a frame or image. For example, a frame may be stored, transmitted, processed, or any combination thereof, in a two-dimensional data structure such as a matrix as shown, or in a onedimensional data structure, such as a vector array. In an implementation, a representation of the frame, such as a two-dimensional representation as shown, may correspond to a physical location in a rendering of the frame as an image. For example, a location in the top left corner of a block in the top left comer of the frame may correspond with a physical location in the top left corner of a rendering of the frame as an image.

[0072] In some implementations, block-based coding efficiency may be improved by partitioning input blocks into one or more prediction partitions, which may be rectangular, including square, partitions for prediction coding. In some implementations, video coding using prediction partitioning may include selecting a prediction partitioning scheme from among multiple candidate prediction partitioning schemes. For example, in some implementations, candidate prediction partitioning schemes for a 64x64 coding unit may include rectangular size prediction partitions ranging in sizes from 4x4 to 64x64, such as 4x4, 4x8, 8x4, 8x8, 8x16, 16x8, 16x16, 16x32, 32x16, 32x32, 32x64, 64x32, or 64x64. In some implementations, video coding using prediction partitioning may include a full prediction partition search, which may include selecting a prediction partitioning scheme by encoding the coding unit using each available candidate prediction partitioning scheme and selecting the best scheme, such as the scheme that produces the least rate-distortion error.

[0073] In some implementations, encoding a video frame may include identifying a prediction partitioning scheme for encoding a current block, such as block 610. In some implementations, identifying a prediction partitioning scheme may include determining whether to encode the block as a single prediction partition of maximum coding unit size, which may be 64x64 as shown, or to partition the block into multiple prediction partitions, which may correspond with the sub-blocks, such as the 32x32 blocks 620 the 16x16 blocks 630, or the 8x8 blocks 640, as shown, and may include determining whether to partition into one or more smaller prediction partitions. For example, a 64x64 block may be partitioned into four 32x32 prediction partitions. Three of the four 32x32 prediction partitions may be encoded as 32x32 prediction partitions and the fourth 32x32 prediction partition may be further partitioned into four 16x16 prediction partitions. Three of the four 16x16 prediction partitions may be encoded as 16x16 prediction partitions and the fourth 16x16 prediction partition may be further partitioned into four 8x8 prediction partitions, each of which may be encoded as an 8x8 prediction partition. In some implementations, identifying the prediction partitioning scheme may include using a prediction partitioning decision tree.

[0074] In some implementations, video coding for a current block may include identifying an optimal prediction coding mode from multiple candidate prediction coding modes, which may provide flexibility in handling video signals with various statistical properties and may improve compression efficiency. For example, a video coder may evaluate each candidate prediction coding mode to identify the optimal prediction coding mode, which may be, for example, the prediction coding mode that minimizes an error metric, such as a rate-distortion cost, for the current block. In some implementations, thecomplexity of searching the candidate prediction coding modes may be reduced by limiting the set of available candidate prediction coding modes based on similarities between the current block and a corresponding prediction block. In some implementations, the complexity of searching each candidate prediction coding mode may be reduced by performing a directed refinement mode search. For example, metrics may be generated for a limited set of candidate block sizes, such as 16x16, 8x8, and 4x4, the error metric associated with each block size may be in descending order, and additional candidate block sizes, such as 4x8 and 8x4 block sizes, may be evaluated.

[0075] In some implementations, block-based coding efficiency may be improved by partitioning a current residual block into one or more transform partitions, which may be rectangular, including square, partitions for transform coding. In some implementations, video coding, such as video coding using transform partitioning, may include selecting a uniform transform partitioning scheme. For example, a current residual block, such as block 610, may be a 64x64 block and may be transformed without partitioning using a 64x64 transform.

[0076] Although not expressly shown in FIG. 6, a residual block may be transform partitioned using a uniform transform partitioning scheme. For example, a 64x64 residual block may be transform partitioned using a uniform transform partitioning scheme including four 32x32 transform blocks, using a uniform transform partitioning scheme including sixteen 16x16 transform blocks, using a uniform transform partitioning scheme including sixty-four 8x8 transform blocks, or using a uniform transform partitioning scheme including 2564x4 transform blocks.

[0077] In some implementations, video coding, such as video coding using transform partitioning, may include identifying multiple transform block sizes for a residual block using multiform transform partition coding. In some implementations, multiform transform partition coding may include recursively determining whether to transform a current block using a current block size transform or by partitioning the current block and multiform transform partition coding each partition. For example, the bottom left block 610 shown in FIG. 6 may be a 64x64 residual block, and multiform transform partition coding may include determining whether to code the current 64x64 residual block using a 64x64 transform or to code the 64x64 residual block by partitioning the 64x64 residual block into partitions, such as four 32x32 blocks 620, and multiform transform partition coding each partition. In some implementations, determining whether to transform partition the current block may be basedon comparing a cost for encoding the current block using a current block size transform to a sum of costs for encoding each partition using partition size transforms.

[0078] FIG. 7 is a block diagram of an example of available partition types 700 for partitioning a current block.

[0079] The available partition types 700 include an unpartitioned partition type 710 (none, partition_none), wherein the current block is unpartitioned. Further partitioning for the current block may be omitted, skipped, or excluded.

[0080] The available partition types 700 include a split partition type 720 (SPLIT or PARTITION_SPLIT) wherein the current block is partitioned horizontally and vertically with biaxial symmetry (horizontal and vertical mirror symmetry) into four subblock partitions (subblocks).

[0081] The available partition types 700 include a horizontal partition type 722 (HORZ or PARTITION_HORZ) wherein the current block is partitioned horizontally into two symmetrical subblock partitions, such as horizontal rectangular subblocks.

[0082] The available partition types 700 include a vertical partition type 724 (VERT or PARTITION_VERT) wherein the current block is partitioned vertically into two symmetrical subblock partitions, such as vertical rectangular subblocks.

[0083] The available partition types 700 include a horizontal-H partition type 730 (HORZ_H or PARTITION_HORZ_H) wherein the current block is partitioned horizontally and vertically with quasi- vertical symmetry into four subblock partitions (subblocks), including a first horizontal rectangular partition corresponding to the top of the current block and having the width of the current block and one-fourth of the height of the current block, a second horizontal rectangular partition corresponding to the bottom of the current block and having the width of the current block and one-fourth of the height of the current block, a left partition having half the width of the current block and half of the height of the current block, and a right partition having half the width of the current block and half of the height of the current block.

[0084] The available partition types 700 include a vertical-H partition type 732 (VERT_H or PARTITION_VERT_H) wherein the current block is partitioned vertically and horizontally with quasi-horizontal symmetry into four subblock partitions (subblocks), including a first vertical rectangular partition corresponding to the left of the current block and having the height of the current block and one-fourth of the width of the current block, a second vertical partition corresponding to the right of the current block and having the height of the current block and one-fourth of the width of the current block, a top partition havinghalf the width of the current block and half of the height of the current block, and a bottom partition having half the width of the current block and half of the height of the current block.

[0085] The horizontal-H partition type 730 and the vertical-H partition type 732 are H-partition types.

[0086] The available partition types 700 include a first uneven horizontal partition type 740 (HORZ_4A or PARTITION_HORZ_4A) wherein the current block is partitioned horizontally with asymmetry into four horizontal rectangular subblock partitions (subblocks), including a first horizontal rectangular partition corresponding to the top of the current block and having the width of the current block and one-eighth of the height of the current block, a second horizontal rectangular partition corresponding to the bottom of the current block and having the width of the current block and one-eighth of the height of the current block, a third horizontal rectangular partition below the first horizontal rectangular partition and having the width of the current block and one-fourth of the height of the current block, and a fourth horizontal rectangular partition below the third horizontal rectangular partition and having the width of the current block and half of the height of the current block.

[0087] The available partition types 700 include a second uneven horizontal partition type 742 (HORZ_4B or PARTITION_HORZ_4B) wherein the current block is partitioned horizontally with asymmetry into four horizontal rectangular subblock partitions (subblocks), including a first horizontal rectangular partition corresponding to the top of the current block and having the width of the current block and one-eighth of the height of the current block, a second horizontal rectangular partition corresponding to the bottom of the current block and having the width of the current block and one-eighth of the height of the current block, a third horizontal rectangular partition below the first horizontal rectangular partition and having the width of the current block and half of the height of the current block, and a fourth horizontal rectangular partition below the second horizontal rectangular partition and having the width of the current block and one-fourth of the height of the current block.

[0088] The available partition types 700 include a first uneven vertical partition type 744 (VERT_4A or PARTITION_VERT_4A) wherein the current block is partitioned vertically with asymmetry into four vertical rectangular subblock partitions (subblocks), including a first vertical rectangular partition corresponding to the left of the current block and having the height of the current block and one-eighth of the width of the current block, a second vertical rectangular partition corresponding to the right of the current block and having the height of the current block and one-eighth of the width of the current block, a third vertical rectangular partition to the right of the first vertical rectangular partition and having the height of thecurrent block and one-fourth of the width of the current block, and a fourth vertical rectangular partition to the right of the third vertical rectangular partition and having the height of the current block and half of the width of the current block.

[0089] The available partition types 700 include a second uneven vertical partition type 746 (VERT_4B or PARTITION- VERT_4B) wherein the current block is partitioned vertically with asymmetry into four vertical rectangular subblock partitions (subblocks), including a first vertical rectangular partition corresponding to the left of the current block and having the height of the current block and one-eighth of the width of the current block, a second vertical rectangular partition corresponding to the right of the current block and having the height of the current block and one-eighth of the width of the current block, a third vertical rectangular partition to the right of the first vertical rectangular partition and having the height of the current block and half of the width of the current block, and a fourth vertical rectangular partition to the right of the third vertical rectangular partition and having the height of the current block and one-fourth of the width of the current block.

[0090] The first uneven horizontal partition type 740, the second uneven horizontal partition type 742, the first uneven vertical partition type 744, and the second uneven vertical partition type 746 are uneven 4-way partition types.

[0091] For partition types other than the unpartitioned partition type, and for some subblock sizes, such as subblocks larger than a minimum subblock size, such as 4x4, the subblocks may be further partitioned (recursive).

[0092] In some implementations, available coding block sizes include coding block sizes having a block partition elongation of one (1) corresponding to a one-to-one ratio (1:1), such as a square 4x4 coding block size, a square 8x8 coding block size, a square 16x16 coding block size, a square 32x32 coding block size, a square 64x64 coding block size, a square 128x128 coding block size, and a square 256x256 coding block size; coding block sizes having a block partition elongation of two (2) corresponding to ratios including a one-to-two ratio (1:2) and a two-to-one ratio (2:1), such as a rectangular 4x8 coding block size, a rectangular 8x4 coding block size, a rectangular 8x16 coding block size, a rectangular 16x8 coding block size, a rectangular 16x32 coding block size, a rectangular 32x16 coding block size, a rectangular 32x64 coding block size, a rectangular 64x32 coding block size, a rectangular 64x128 coding block size, a rectangular 128x64 coding block size, a rectangular 128x256 coding block size, and a rectangular 256x128 coding block size; coding block sizes having a block partition elongation of four (4) corresponding to ratios including a one-to-four ratio (1:4) and a four-to-one ratio (4:1), such as a rectangular 4x16 coding block size, a -11-rectangular 16x4 coding block size, a rectangular 8x32 coding block size, a rectangular 32x8 coding block size, a rectangular 16x64 coding block size, and a rectangular 64x16 coding block size; coding block sizes having a block partition elongation of eight (8) corresponding to ratios including a one-to-eight ratio (1:8) and an eight-to-one ratio (8:1), such as a rectangular 4x32 coding block size, a rectangular 32x4 coding block size, a rectangular 8x64 coding block size, and a rectangular 64x8 coding block size; coding block sizes having a block partition elongation of sixteen (16) corresponding to ratios including a one-to- sixteen ratio (1:16) and a sixteen-to-one ratio (16:1), such as a rectangular 4x64 coding block size, and a rectangular 64x4 coding block size. Coding block sizes other than the available coding block sizes are unavailable, prevented, or excluded. As used herein, the term “elongation” refers to, or indicates, the magnitude of the aspect ratio of the dimensions of a block independent of orientation.

[0093] FIG. 8 is a flowchart diagram of an example of obtaining block partition symbols 800. Obtaining block partition symbols 800 may be implemented in an encoder, such as the encoder 400 shown in FIG. 4, or one or more portions thereof, or a decoder, such as the decoder 500 shown in FIG. 5, or one or more portions thereof.

[0094] Obtaining block partition symbols 800 includes determining a sequence or series of binary tokens, flags, or symbols (a sequence of block partition symbols), or values thereof, including a split-partition symbol, flag, or token (split), a square-split-partition symbol, flag, or token (square_split), a rectangular-type-partition symbol, flag, or token (rect_type), an extended-partition symbol, flag, or token (ext), a four-way-partition symbol, flag, or token (4way), and an A-or-B -partition symbol, flag, or token (a_or_b). The tokens, flags, or symbols may be derived implicitly or signaled using corresponding context models.

[0095] Obtaining block partition symbols 800 includes determining whether the splitpartition symbol, flag, or token indicates that the current block is partitioned (SPLIT?) (at 810). The split-partition symbol, flag, or token may have a first value, such as zero (0), indicating that the current block is unpartitioned (NONE at 812) and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block. The splitpartition symbol, flag, or token may have a second value, such as one (1), indicating that the current block is partitioned.

[0096] Obtaining block partition symbols 800 may include, such as wherein the splitpartition symbol, flag, or token indicates that the current block is partitioned, determining whether the square- split-partition symbol, flag, or token indicates that the current block is partitioned using a split partition type, such as the split partition type 720 shown in FIG. 7,(SQUARE SPLIT?) (at 820). The square-split-partition symbol, flag, or token may have a first value, such as one (1), indicating that the current block is partitioned using the split partition type (SPLIT at 822) and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block. The square-split-partition symbol, flag, or token may have a second value, such as zero (0), indicating that the current block is partitioned using a partition type other than the split partition type.

[0097] Obtaining block partition symbols 800 may include, such as wherein the square-split-partition symbol, flag, or token indicates that the current block is partitioned using a partition type other than the split partition type, determining whether the rectangular-typepartition symbol, flag, or token indicates that the current block is partitioned using a horizontal partition type, such as the horizontal partition type 722, the horizontal-H partition type 730, the first uneven horizontal partition type 740, or the second uneven horizontal partition type 742 shown in EIG. 7, or a vertical partition type, such as the vertical partition type 724, the vertical-H partition type 732, the first uneven vertical partition type 744, or the second uneven vertical partition type 746 shown in EIG. 7, (RECT TYPE?) (at 830). The rectangular-type-partition symbol, flag, or token may have a first value, such as zero (0), which is shown as HORZ (at 832) in FIG. 8 for clarity, indicating that the current block is partitioned using a horizontal partition type. The rectangular-type-partition, flag, or token may have a second value, such as one (1), which is shown as VERT (at 834) in FIG. 8 for clarity, indicating that the current block is partitioned using a vertical partition type.

[0098] Obtaining block partition symbols 800 may include, such as wherein the rectangular-type-partition symbol, flag, or token indicates that the current block is partitioned using a horizontal partition type, determining whether the extended-partition symbol, flag, or token indicates that the current block is partitioned using a symmetrical horizontal partition type, such as the horizontal partition type 722 shown in FIG. 7, (EXT?) (at 840). The extended-partition symbol, flag, or token may have a first value, such as zero, indicating that the current block is partitioned using the symmetrical horizontal partition type (HORZ at 842) and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block. The extended-partition symbol, flag, or token may have a second value, such as one, indicating that the current block is partitioned using an asymmetrical horizontal partition type, such as the horizontal-H partition type 730, the first uneven horizontal partition type 740, or the second uneven horizontal partition type 742 shown in FIG. 7.

[0099] Obtaining block partition symbols 800 may include, such as wherein the extended-partition symbol, flag, or token indicates that the current block is partitioned using an asymmetrical horizontal partition type, determining whether the four-way-partition symbol, flag, or token indicates that the current block is partitioned using an uneven four-way partition type, such as the first uneven horizontal partition type 740 or the second uneven horizontal partition type 742 shown in FIG. 7, (4WAY?) (at 850). The four-way-partition symbol, flag, or token may have a first value, such as zero (0), indicating that the current block is partitioned using an H-partition type (HORZ_H at 852), such as the horizontal-H partition type 730 shown in FIG. 7, and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block. The four- way-partition symbol, flag, or token may have a second value, such as one (1), indicating that the current block is partitioned using an uneven four- way partition type, such as the first uneven horizontal partition type 740 or the second uneven horizontal partition type 742 shown in FIG. 7.

[0100] Obtaining block partition symbols 800 may include, such as wherein the four-way-partition symbol, flag, or token indicates that the current block is partitioned using an uneven four- way partition type, determining whether the A-or-B -partition symbol, flag, or token indicates that the current block is partitioned using the first uneven horizontal partition type, such as the first uneven horizontal partition type 740 shown in FIG. 7, (A OR B?) (at 860). The A-or-B -partition symbol, flag, or token may have a first value, such as zero (0, shown as A in FIG. 8 for clarity), indicating that the current block is partitioned using the first uneven horizontal partition type (HORZ_4A at 862), and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block. The A-or-B-partition symbol, flag, or token may have a second value, such as one (1, shown as B in FIG.8 for clarity), indicating that the current block is partitioned using the second uneven horizontal partition type, such as the second uneven horizontal partition type 742 shown in FIG. 7, (HORZ_4B at 864), and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block.

[0101] Obtaining block partition symbols 800 may include, such as wherein the rectangular-type-partition symbol, flag, or token indicates that the current block is partitioned using a vertical partition type, determining whether the extended-partition symbol, flag, or token indicates that the current block is partitioned using a symmetrical vertical partition type, such as the vertical partition type 724 shown in FIG. 7, (EXT?) (at 870). The extended-partition symbol, flag, or token may have a first value, such as zero (0), indicating that the current block is partitioned using the symmetrical vertical partition type (VERT at 872) andobtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block. The extended-partition symbol, flag, or token may have a second value, such as one (1), indicating that the current block is partitioned using an asymmetrical vertical partition type, such as the vertical-H partition type 732, the first uneven vertical partition type 744, or the second uneven vertical partition type 746 shown in FIG. 7.

[0102] Obtaining block partition symbols 800 may include, such as wherein the extended-partition symbol, flag, or token indicates that the current block is partitioned using an asymmetrical vertical partition type, determining whether the four-way-partition symbol, flag, or token indicates that the current block is partitioned using an uneven four- way partition type, such as the first uneven vertical partition type 744 or the second uneven vertical partition type 746 shown in FIG. 7, (4WAY?) (at 880). The four-way-partition symbol, flag, or token may have a first value, such as zero (0), indicating that the current block is partitioned using an H-partition type (VERT_H at 882), such as the vertical-H partition type 732 shown in FIG. 7, and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block. The four- way-partition symbol, flag, or token may have a second value, such as one (1), indicating that the current block is partitioned using the uneven four- way partition type, such as the first uneven vertical partition type 744 or the second uneven vertical partition type 746 shown in FIG. 7.

[0103] Obtaining block partition symbols 800 may include, such as wherein the four-way-partition symbol, flag, or token indicates that the current block is partitioned using an uneven four- way partition type, determining whether the A-or-B -partition symbol, flag, or token indicates that the current block is partitioned using a first uneven vertical partition type, such as the first uneven vertical partition type 744 shown in FIG. 7, (A OR B?) (at 890). The A-or-B -partition symbol, flag, or token may have a first value, such as zero (0, shown as A in FIG. 8 for clarity), indicating that the current block is partitioned using the first uneven vertical partition type (VERT_4A at 892), and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block. The A-or-B-partition symbol, flag, or token may have a second value, such as one (1, shown as B in FIG. 8 for clarity), indicating that the current block is partitioned using a second uneven vertical partition type, such as the second uneven vertical partition type 746 shown in FIG. 7, (VERT_4B at 894), and obtaining block partition symbols 800 may be otherwise omitted, skipped, or excluded for the current block.

[0104] FIG. 9 is a flowchart diagram of an example of decoding using partition aspect ratio constraints 900 in accordance with implementations of this disclosure. Decoding usingpartition aspect ratio constraints 900 may be implemented in a decoder, such as the decoder 500 shown in FIG. 5.

[0105] Decoding using partition aspect ratio constraints 900 includes obtaining reconstructed block data for a current block of a current frame, such as an image or a frame of a sequence of frames, by decoding an encoded bitstream, such as the compressed bitstream 502 shown in FIG. 5, or one or more portions thereof, to generate a reconstructed video, or a portion thereof, such as the output video stream 504 shown in FIG. 5.

[0106] Decoding using partition aspect ratio constraints 900 includes obtaining the encoded bitstream (at 910), accessing block partition aspect ratio constraint data (at 920), obtaining block partition symbols (at 930), partitioning the current block (at 940), generating reconstructed block data (at 950), and outputting the reconstructed data (at 960).

[0107] The encoded bitstream is obtained (at 910). For example, the decoder may obtain the encoded bitstream, such as the encoded (compressed) bitstream 404 shown in FIG. 4 or the compressed bitstream 502 shown in FIG. 5.

[0108] Accessing the block partition aspect ratio constraint data (at 920) includes accessing, from the encoded bitstream, the block partition aspect ratio constraint data indicating a maximum block partition elongation, which may include decoding encoded block partition aspect ratio constraint data from the encoded bitstream.

[0109] In some implementations, accessing the block partition aspect ratio constraint data (at 920) includes accessing the block partition aspect ratio constraint data from a sequence header for a sequence of frames that includes the current frame.

[0110] In some implementations, accessing the block partition aspect ratio constraint data (at 920) includes accessing the block partition aspect ratio constraint data from a frame header for the current frame.

[0111] In some implementations, accessing the block partition aspect ratio constraint data (at 920) includes accessing the block partition aspect ratio constraint data from a tile header for a tile that includes the current block.

[0112] In some implementations, accessing the block partition aspect ratio constraint data (at 920) includes accessing, from the encoded bitstream, an index value corresponding to the maximum block partition elongation in an index of available maximum block partition elongations. For example, the available maximum block partition elongations may include 16 corresponding to an index value of zero (0), 8 corresponding to an index value of one (1), 4 corresponding to an index value of two (2), and 2 corresponding to an index value of three (3). Other techniques for signaling the maximum block partition elongation may be used.

[0113] Decoding using partition aspect ratio constraints 900 includes identifying a current frame to decode from the encoded bitstream to generate a current reconstructed frame, which includes identifying a current block from the current frame to decode from the encoded bitstream to generate a current reconstructed block to include in the current reconstructed frame. For example, the decoder, or a component thereof, such as an intra / inter prediction unit of the decoder, such as the entropy decoding unit 510 shown in FIG. 5, may obtain the encoded bitstream. The current frame may be obtained subsequent to decoding one or more other frames, such as a frame sequentially preceding the current frame, and generating, or otherwise obtaining, a corresponding reconstructed frame (or frames), or one or more portions thereof, for use as a reference frame (or frames) for decoding the current frame. Although not shown separately in FIG. 9, decoding using partition aspect ratio constraints 900 may include decoding, reconstructing, or both, one or more portions of the current frame prior to decoding, reconstructing, or both, the current block.

[0114] Obtaining the block partition symbols (at 930) includes obtaining a sequence of block partition symbols for the current block. Obtaining the block partition symbols (at 930) is similar to obtaining block partition symbols 800 as shown in FIG. 8, except as is described herein or as is otherwise clear from context.

[0115] Obtaining the sequence of block partition symbols includes identifying a sequentially first symbol, such as the split-partition symbol, flag, or token, from the sequence of block partition symbols as a current symbol and obtaining a value of the current symbol by entropy decoding the value of the sequentially first symbol from the encoded bitstream.

[0116] In some implementations, obtaining the sequence of block partition symbols includes determining whether the value of the split-partition symbol, flag, or token is first available value, such as zero (0), indicating that the current block is an unpartitioned block, or a second available value, such as one (1), indicating that the current block is a partitioned block, which may be similar to the determining shown (at 810) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0117] In some implementations, the value of the split-partition symbol, flag, or token is the first available value, such as zero (0), indicating that the current block is an unpartitioned block, the partition type for the current block is identified as the unpartitioned partition type, and obtaining the subsequent symbols of the sequence of block partition symbols may be omitted, skipped, avoided, or excluded.

[0118] In some implementations, the value of the split-partition symbol, flag, or token is the second available value, such as one (1), indicating that the current block is a partitionedblock, and, subsequent to obtaining the value of the sequentially first symbol, obtaining the sequence of block partition symbols includes identifying a sequentially second symbol, such as square- split-partition symbol, flag, or token, of the sequence of block partition symbols as the current symbol and determining whether partitioning the current block in accordance with a first available value, such as zero (0), of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0119] For example, the current block may be a square block, the maximum block partition elongation may be one (1), and the decoder may determine that partitioning the current block in accordance with the first available value (0) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of two (2), four (4), eight (8), or sixteen (16).

[0120] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the square-split-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as the value of the current symbol, a second available value, such as one (1), of the current symbol. In implementations wherein partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the square- split-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, data indicating the value of the current symbol, such as data encoding the value of the current symbol, is absent, omitted, or unavailable from the encoded bitstream.

[0121] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the square-split-partition symbol, corresponds with partition elongations that are less than or equal to the maximum block partition elongation, obtaining a value of the current symbol by entropy decoding the value of the square-split-partition symbol from the encoded bitstream.

[0122] Obtaining the sequence of block partition symbols includes determining whether the value of the current symbol, wherein the current symbol is the square-split-partition symbol, is the first available value (0), indicating that the current block is partitioned using a partition type other than the split partition type, or the second available value (1), indicating that the current block is partitioned using the split partition type, such as the split partitiontype 720 shown in FIG. 7, which may be similar to the determination shown (at 820) in FIG.8, except as is described herein or as is otherwise clear from context.

[0123] In response to a determination that the value of the square- split-partition symbol is the second available value (1), indicating that the current block is partitioned using the split partition type, the partition type for the current block is identified as the split partition type, and obtaining the sequence of block partition symbols is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the split partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 980) from partitioning the current block (at 940) to obtaining block partition symbols (at 930).

[0124] In some implementations, the value of the square- split-partition symbol, flag, or token is the first available value (0), indicating that the current block is partitioned using a partition type other than the split partition type, and obtaining the sequence of block partition symbols includes, subsequent to obtaining the value of the square- split-partition symbol, flag, or token, identifying a sequentially third symbol, such as the rectangular-type-partition symbol, flag, or token, of the sequence of block partition symbols as the current symbol and determining whether partitioning the current block in accordance with a first available value, such as zero (0), such as shown (at 832) in FIG. 8, of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0125] For example, the current block may be a 64x16 block, the maximum block partition elongation may be four (4), and the decoder may determine that partitioning the current block in accordance with the first available value (0) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of eight (8) or sixteen (16).

[0126] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the rectangular-type-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as the value of the current symbol, a second available value, such as one (1), such as is shown as VERT (at 834) in FIG. 8, of the current symbol. In implementations wherein partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the rectangular-type-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, data indicating the value of the current symbol is absent, omitted, or unavailable from the encoded bitstream.

[0127] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the rectangular-type-partition symbol, corresponds with partition elongations that are less than or equal to the maximum block partition elongation, obtaining a value of the current symbol by entropy decoding the value of the rectangular-type-partition symbol from the encoded bitstream.

[0128] Obtaining the sequence of block partition symbols includes determining whether the value of the current symbol, wherein the current symbol is the rectangular-type-partition symbol, is the first available value (0), indicating that the current block is partitioned using a horizontally oriented partition type, such as the horizontal partition type 722 shown in FIG. 7, the horizontal-H partition type 730 shown in FIG. 7, the first uneven horizontal partition type 740 shown in FIG. 7, or the second uneven horizontal partition type 742, or the second available value (1), indicating that the current block is partitioned using a vertical partition type, such as the vertical partition type 724 shown in FIG. 7, the vertical-H partition type 732 shown in FIG. 7, the first uneven vertical partition type 744 shown in FIG. 7, or the second uneven vertical partition type 746, which may be similar to the determination shown (at 830) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0129] In some implementations, the value of the rectangular-type-partition symbol, flag, or token is the first available value (0), indicating that the current block is partitioned using a horizontally oriented partition type, and obtaining the sequence of block partition symbols includes, subsequent to obtaining the value of the rectangular-type-partition symbol, flag, or token, identifying a sequentially fourth symbol, flag, or token, such as the extended-partition symbol, flag, or token, of the sequence of block partition symbols as the current symbol and determining whether partitioning the current block in accordance with a first available value, such as zero (0), of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0130] For example, the current block may be a 64x64 block, the maximum block partition elongation may be two (2), and the decoder may determine that partitioning the current block in accordance with the first available value (0) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are,greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of four (4), eight (8) or sixteen (16).

[0131] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the extended-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as the value of the current symbol, a second available value, such as one (1), of the current symbol. In implementations wherein partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the extended-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, data indicating the value of the current symbol is absent, omitted, or unavailable from the encoded bitstream.

[0132] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the extended-partition symbol, corresponds with partition elongations that are less than or equal to the maximum block partition elongation, obtaining a value of the current symbol by entropy decoding the value of the extended-partition symbol from the encoded bitstream.

[0133] Obtaining the sequence of block partition symbols includes determining whether the value of the current symbol, wherein the current symbol is the extended-partition symbol, is the first available value (0), indicating that the current block is partitioned using the horizontal partition type, or the second available value (1), indicating that the current block is partitioned using a horizontally oriented partition type other than the horizontal partition type, which may be similar to the determination shown (at 840) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0134] In response to a determination that the value of the extended-partition symbol is the first available value (0), indicating that the current block is partitioned using the horizontal partition type, the partition type for the current block is identified as the horizontal partition type, and obtaining the sequence of block partition symbols is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the horizontal partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, asindicated by the broken directional line (at 980) from partitioning the current block (at 940) to obtaining block partition symbols (at 930).

[0135] In some implementations, the value of the extended-partition symbol, flag, or token is the second available value (1), indicating that the current block is partitioned using a horizontally oriented partition type other than the horizontal partition type, and obtaining the sequence of block partition symbols includes, subsequent to obtaining the value of the extended-partition symbol, flag, or token, identifying a sequentially fifth symbol, flag, or token, such as the four-way-partition symbol, flag, or token, of the sequence of block partition symbols as the current symbol and determining whether partitioning the current block in accordance with a first available value, such as one (1), of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0136] For example, the current block may be a 64x32 block, the maximum block partition elongation may be eight (8), and the decoder may determine that partitioning the current block in accordance with the first available value (1) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of sixteen (16).

[0137] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (1) of the current symbol, wherein the current symbol is the four- way -partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as the value of the current symbol, a second available value, such as zero (0), of the current symbol. In implementations wherein partitioning the current block in accordance with the first available value (1) of the current symbol, wherein the current symbol is the four-way-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, data indicating the value of the current symbol is absent, omitted, or unavailable from the encoded bitstream.

[0138] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (1) of the current symbol, wherein the current symbol is the four- way -partition symbol, corresponds with partition elongations that are less than or equal to themaximum block partition elongation, obtaining a value of the current symbol by entropy decoding the value of the four-way-partition symbol from the encoded bitstream.

[0139] Obtaining the sequence of block partition symbols includes determining whether the value of the current symbol, wherein the current symbol is the four-way-partition symbol, is the first available value (1), indicating that the current block is partitioned using an uneven horizontal partition type, or the second available value (0), indicating that the current block is partitioned using the horizontal-H partition type, which may be similar to the determination shown (at 850) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0140] In response to a determination that the value of the four- way-partition symbol is the second available value (0), indicating that the current block is partitioned using the horizontal-H partition type, the partition type for the current block is identified as the horizontal-H partition type, and obtaining the sequence of block partition symbols is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the horizontal-H partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 980) from partitioning the current block (at 940) to obtaining block partition symbols (at 930).

[0141] In some implementations, the value of the four-way-partition symbol, flag, or token is the first available value (1), indicating that the current block is partitioned using an uneven horizontal partition type, and obtaining the sequence of block partition symbols includes, subsequent to obtaining the value of the four-way-partition symbol, flag, or token, identifying a sequentially sixth symbol, flag, or token, such as the A- or-B -partition symbol, flag, or token, of the sequence of block partition symbols as the current symbol and obtaining a value of the current symbol by entropy decoding the value of the A-or-B -partition symbol from the encoded bitstream.

[0142] Obtaining the sequence of block partition symbols includes determining whether the value of the current symbol, wherein the current symbol is the A-or-B -partition symbol, is the first available value (0), which is shown as A in FIG. 8, indicating that the current block is partitioned using the first uneven horizontal partition type, wherein the partition type for the current block is identified as the first uneven horizontal partition type, or the second available value (1), which is shown as B in FIG. 8, indicating that the current block is partitioned using the second uneven horizontal partition type, wherein the partition type for the current block is identified as the second uneven horizontal partition type, which may be similar to thedetermination shown (at 860) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0143] One or more of the subblocks obtained by partitioning the current block in accordance with the uneven horizontal partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 980) from partitioning the current block (at 940) to obtaining block partition symbols (at 930).

[0144] In some implementations, the value of the rectangular-type-partition symbol, flag, or token is the second available value (1), indicating that the current block is partitioned using a vertically oriented partition type, and obtaining the sequence of block partition symbols includes, subsequent to obtaining the value of the rectangular-type-partition symbol, flag, or token, identifying the sequentially fourth symbol, flag, or token, such as the extended-partition symbol, flag, or token, of the sequence of block partition symbols as the current symbol and determining whether partitioning the current block in accordance with the first available value, such as zero (0), of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0145] For example, the current block may be a 64x64 block, the maximum block partition elongation may be two (2), and the decoder may determine that partitioning the current block in accordance with the first available value (0) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of four (4), eight (8) or sixteen (16).

[0146] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the extended-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as the value of the current symbol, the second available value, such as one (1), of the current symbol. In implementations wherein partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the extended-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, data indicating the value of the current symbol is absent, omitted, or unavailable from the encoded bitstream.

[0147] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the extended-partition symbol, corresponds with partition elongations that are less than or equal to the maximum block partition elongation, obtaining the value of the current symbol by entropy decoding the value of the extended-partition symbol from the encoded bitstream.

[0148] Obtaining the sequence of block partition symbols includes determining whether the value of the current symbol, wherein the current symbol is the extended-partition symbol, is the first available value (0), indicating that the current block is partitioned using the vertical partition type, or the second available value (1), indicating that the current block is partitioned using the vertically oriented partition type other than the vertical partition type, which may be similar to the determination shown (at 870) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0149] In response to a determination that the value of the extended-partition symbol is the first available value (0), indicating that the current block is partitioned using the vertical partition type, the partition type for the current block is identified as the vertical partition type, and obtaining the sequence of block partition symbols is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the vertical partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 980) from partitioning the current block (at 940) to obtaining block partition symbols (at 930).

[0150] In some implementations, the value of the extended-partition symbol, flag, or token is the second available value (1), indicating that the current block is partitioned using the vertically oriented partition type other than the vertical partition type, and obtaining the sequence of block partition symbols includes, subsequent to obtaining the value of the extended-partition symbol, flag, or token, identifying the sequentially fifth symbol, flag, or token, such as the four-way-partition symbol, flag, or token, of the sequence of block partition symbols as the current symbol and determining whether partitioning the current block in accordance with the first available value, such as one (1), of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0151] For example, the current block may be a 32x64 block, the maximum block partition elongation may be eight (8), and the decoder may determine that partitioning thecurrent block in accordance with the first available value (1) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of sixteen (16).

[0152] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (1) of the current symbol, wherein the current symbol is the four- way -partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as the value of the current symbol, the second available value, such as zero (0), of the current symbol. In implementations wherein partitioning the current block in accordance with the first available value (1) of the current symbol, wherein the current symbol is the four-way-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, data indicating the value of the current symbol is absent, omitted, or unavailable from the encoded bitstream.

[0153] In some implementations, obtaining the sequence of block partition symbols includes, in response to determining that partitioning the current block in accordance with the first available value (1) of the current symbol, wherein the current symbol is the four- way -partition symbol, corresponds with partition elongations that are less than or equal to the maximum block partition elongation, obtaining the value of the current symbol by entropy decoding the value of the four-way-partition symbol from the encoded bitstream.

[0154] Obtaining the sequence of block partition symbols includes determining whether the value of the current symbol, wherein the current symbol is the four-way-partition symbol, is the first available value (1), indicating that the current block is partitioned using an uneven vertical partition type, or the second available value (0), indicating that the current block is partitioned using the vertical-H partition type, which may be similar to the determination shown (at 880) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0155] In response to a determination that the value of the four- way-partition symbol is the second available value (0), indicating that the current block is partitioned using the vertical-H partition type, the partition type for the current block is identified as the vertical-H partition type, and obtaining the sequence of block partition symbols is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the vertical-H partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, asindicated by the broken directional line (at 980) from partitioning the current block (at 940) to obtaining block partition symbols (at 930).

[0156] In some implementations, the value of the four-way-partition symbol, flag, or token is the first available value (1), indicating that the current block is partitioned using an uneven vertical partition type, and obtaining the sequence of block partition symbols includes, subsequent to obtaining the value of the four-way-partition symbol, flag, or token, identifying the sequentially sixth symbol, flag, or token, such as the A-or-B -partition symbol, flag, or token, of the sequence of block partition symbols as the current symbol and obtaining the value of the current symbol by entropy decoding the value of the A-or-B-partition symbol from the encoded bitstream.

[0157] Obtaining the sequence of block partition symbols includes determining whether the value of the current symbol, wherein the current symbol is the A-or-B-partition symbol, is the first available value (0), which is shown as A in FIG. 8, indicating that the current block is partitioned using the first uneven vertical partition type, wherein the partition type for the current block is identified as the first uneven vertical partition type, or the second available value (1), which is shown as B in FIG. 8, indicating that the current block is partitioned using the second uneven vertical partition type, wherein the partition type for the current block is identified as the second uneven vertical partition type, which may be similar to the determination shown (at 890) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0158] One or more of the subblocks obtained by partitioning the current block in accordance with the uneven vertical partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 980) from partitioning the current block (at 940) to obtaining block partition symbols (at 930).

[0159] Partitioning the current block (at 940) includes partitioning the current block in accordance with the sequence of block partition symbols, such as in accordance with the partition type identified for the current block by the sequence of block partition symbols.

[0160] Generating reconstructed block data (at 950) includes generating the reconstructed block data for the current block in response to the determination that the current block is and unpartitioned block.

[0161] Generating the reconstructed block data may include aspects not expressly shown in FIG. 9 for simplicity, such as filtering, such as the filtering shown (at 560) in FIG. 5.

[0162] Outputting the reconstructed data (at 960) includes including the reconstructed block data in reconstructed frame data for the current frame and outputting the reconstructed frame data.

[0163] FIG. 10 is a flowchart diagram of an example of encoding using partition aspect ratio constraints 1000 in accordance with implementations of this disclosure. Encoding using partition aspect ratio constraints 1000 may be implemented in an encoder, such as the encoder 400 shown in FIG. 4, or one or more portions thereof.

[0164] Encoding using partition aspect ratio constraints 1000 includes generating an encoded bitstream by encoding a current block from a current frame from an input video, such as the input video stream 402 shown in FIG. 4, or one or more portions thereof, to generate an encoded (compressed) output bitstream, such as the encoded (compressed) bitstream 404 shown in FIG. 4, or one or more portions thereof. In block-based hybrid video coding, to reduce, or minimize, resource utilization, such as bandwidth utilization, for signaling, storing, or both, compressed, or encoded, video data, redundant data, such as spatially redundant data, temporally redundant data, or both, is omitted or excluded from the compressed, or encoded, data. For example, spatial redundancy may be reduced using intra prediction, wherein the current block is predicted from the current frame. In another example, temporal redundancy may be reduced using inter prediction, wherein the current block is predicted from one or more reference frames, which may be previously decoded (and reconstructed) frames, constructed reference frames, or both.

[0165] Encoding using partition aspect ratio constraints 1000 includes signaling block partition aspect ratio constraint data (at 1010), obtaining a current block (at 1020), obtaining block partition symbols (at 1030), signaling the block partition symbols with contextual omission (at 1040), and outputting an encoded bitstream (at 1050).

[0166] Signaling the block partition aspect ratio constraint data (at 1010) comprises including, in the encoded bitstream, the block partition aspect ratio constraint data indicating a maximum block partition elongation.

[0167] In some implementations, including, in the encoded bitstream, the block partition aspect ratio constraint data comprises including the block partition aspect ratio constraint data in a sequence header for a sequence of frames that includes the current frame.

[0168] In some implementations, including, in the encoded bitstream, the block partition aspect ratio constraint data comprises including the block partition aspect ratio constraint data in a frame header for the current frame.

[0169] In some implementations, including, in the encoded bitstream, the block partition aspect ratio constraint data comprises including the block partition aspect ratio constraint data in a tile header for a tile from the current frame, wherein the tile (current tile) includes the current block.

[0170] In some implementations, including, in the encoded bitstream, the block partition aspect ratio constraint data comprises identifying one or more coding block sizes as unavailable, or otherwise identifying, as available coding block sizes, a proper subset of the coding block sizes otherwise described herein as available coding block sizes. For example, the encoder may identify one or more of the coding block sizes otherwise described herein as available coding block sizes as unavailable, such as unavailable for the current sequence of frames, unavailable for the current frame, or unavailable for the current tile, and may identify the maximum block partition elongation in accordance with the available coding block sizes corresponding to the proper subset.

[0171] In some implementations, including, in the encoded bitstream, the block partition aspect ratio constraint data comprises including, in the encoded bitstream, an index value corresponding to the maximum block partition elongation in an index of available maximum block partition elongations. For example, the available maximum block partition elongations may include 16 corresponding to an index value of zero (0), 8 corresponding to an index value of one (1), 4 corresponding to an index value of two (2), and 2 corresponding to an index value of three (3). Other techniques for signaling the maximum block partition elongation may be used.

[0172] Encoding using partition aspect ratio constraints 1000 includes obtaining the current frame. The current frame is a frame from the input video, or input video stream. In some implementations, the input video stream may include one or more sequences of frames. A sequence of frames may have a defined cardinality, or number, of frames. For example, the encoder, or a component thereof, such as an intra / inter prediction unit of the encoder, such as the intra / inter prediction unit 410 shown in FIG. 4, may obtain the input video stream. The current frame may be obtained subsequent to encoding one or more other frames, such as a frame sequentially preceding the current frame in the input video stream, and generating, or otherwise obtaining, a corresponding reconstructed frame (or frames), or one or more portions thereof, for use as a reference frame (or frames) for encoding the current frame.

[0173] The current block is obtained (at 1020) from the current frame. Although not shown separately in FIG. 10, encoding using partition aspect ratio constraints 1000 may include encoding, reconstructing, or both, one or more portions of the current frame prior toencoding the current block. Encoding using partition aspect ratio constraints 1000 includes encoding the current block.

[0174] Obtaining the block partition symbols (at 1030) includes obtaining a sequence of block partition symbols for the current block. Obtaining the block partition symbols (at 1030) is similar to obtaining block partition symbols 800 as shown in FIG. 8, except as is described herein or as is otherwise clear from context.

[0175] Signaling the block partition symbols with contextual omission (at 1040) includes determining, on a per-symbol basis, whether to signal, or omit signaling, the respective symbol.

[0176] Signaling the block partition symbols with contextual omission (at 1040) includes identifying a sequentially first symbol, such as the split-partition symbol, flag, or token, from the sequence of block partition symbols as a current symbol and obtaining a value of the current symbol. The value of the split-partition symbol, flag, or token may be a first available value, such as zero (0), indicating that the current block is an unpartitioned block, or a second available value, such as one (1), indicating that the current block is a partitioned block.

[0177] Signaling the block partition symbols with contextual omission (at 1040) includes signaling, such as by including data, such as entropy coded data, indicating the value of the split-partition symbol, flag, or token, in the encoded bitstream.

[0178] In some implementations, on a condition that, or in response to a determination that, the value of the split-partition symbol, flag, or token is the first available value (0), indicating that the current block is an unpartitioned block, signaling the block partition symbols with contextual omission (at 1040) is otherwise omitted, skipped, or excluded for the current block.

[0179] In some implementations, the value of the split-partition symbol, flag, or token is the second available value, such as one (1), indicating that the current block is a partitioned block, and, subsequent to obtaining the value of the sequentially first symbol, signaling the block partition symbols with contextual omission (at 1040) includes identifying a sequentially second symbol, such as the square-split-partition symbol, flag, or token, from the sequence of block partition symbols as a current symbol and obtaining a value of the current symbol. The value of the square-split-partition symbol, flag, or token may be a first available value, such as zero (0), indicating that the current block is partitioned using a partition type other than the split partition type (or the unpartitioned partition type), or a second available value, such as one (1), indicating that the current block is partitioned using the split partition type, such as the split partition type 720 shown in FIG. 7.

[0180] Signaling the block partition symbols with contextual omission (at 1040) includes determining whether partitioning the current block in accordance with the first available value, such as zero (0), of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0181] For example, the current block may be a square block, the maximum block partition elongation may be one (1), and the encoder may determine that partitioning the current block in accordance with the first available value (0) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of two (2), four (4), eight (8), or sixteen (16).

[0182] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the square- split-partition symbol, corresponds with a block partition elongation that is greater than the maximum block partition elongation, omitting, skipping, avoiding, or excluding, signaling, or otherwise including, data indicating the value of the current symbol in the encoded bitstream.

[0183] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the square- split-partition symbol, corresponds with a block partition elongation that is less than or equal to the maximum block partition elongation, signaling, or otherwise including, data indicating the value of the current symbol (e.g., the square- split-partition symbol) in the encoded bitstream.

[0184] In some implementations, on a condition that, or in response to a determination that, the value of the square-split-partition symbol, flag, or token is the second available value (1), indicating that the current block is partitioned using the split partition type, signaling the block partition symbols with contextual omission (at 1040) is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the split partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 1060) from signaling the block partition symbols with contextual omission (at 1040) to obtaining the current block (at 1020).

[0185] In some implementations, the value of the square- split-partition symbol, flag, or token is the first available value, such as zero (0), indicating that the current block is partitioned using a partition type other than the split partition type, and, subsequent to obtaining the value of the sequentially second symbol, signaling the block partition symbols with contextual omission (at 1040) includes identifying a sequentially third symbol, such as the rectangular-type-partition symbol, flag, or token, from the sequence of block partition symbols as a current symbol and obtaining a value of the current symbol. The value of the rectangular-type-partition symbol, flag, or token may be a first available value, such as zero (0), indicating that the current block is partitioned using a horizontally oriented partition type, or a second available value, such as one (1), indicating that the current block is partitioned using a vertically oriented partition type.

[0186] Signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, the value of the current symbol is the second available value (1), determining whether partitioning the current block in accordance with the first available value, such as zero (0), of the current symbol corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0187] For example, the current block may be a 64x16 block, the maximum block partition elongation may be four (4), and the encoder may determine that partitioning the current block in accordance with the first available value (0) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of eight (8) or sixteen (16).

[0188] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the rectangular-type-partition symbol and wherein the value of the current symbol is the second available value (1), corresponds with a block partition elongation that is greater than the maximum block partition elongation, omitting, skipping, avoiding, or excluding, signaling, or otherwise including, data indicating the value of the current symbol in the encoded bitstream.

[0189] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the first available value (0) of the current symbol, wherein the current symbol is the rectangular-type-partition symbol and wherein thevalue of the current symbol is the second available value (1), corresponds with a block partition elongation that is less than or equal to the maximum block partition elongation, signaling, or otherwise including, data indicating the value of the current symbol (e.g., the rectangular-type-partition symbol) in the encoded bitstream.

[0190] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the rectangular-type-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation, omitting, skipping, avoiding, or excluding, signaling, or otherwise including, data indicating the value of the current symbol in the encoded bitstream.

[0191] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the rectangular-type-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is less than or equal to the maximum block partition elongation, signaling, or otherwise including, data indicating the value of the current symbol (e.g., the rectangular-type-partition symbol) in the encoded bitstream.

[0192] In some implementations, the value of the rectangular-type-partition symbol, flag, or token is the first available value, such as zero (0), indicating that the current block is partitioned using a horizontally oriented partition type, and, subsequent to obtaining the value of the sequentially third symbol, signaling the block partition symbols with contextual omission (at 1040) includes identifying a sequentially fourth symbol, such as the extended-partition symbol, flag, or token, from the sequence of block partition symbols as a current symbol and obtaining a value of the current symbol. The value of the extended-partition symbol, flag, or token may be a first available value, such as zero (0), indicating that the current block is partitioned using the horizontal partition type, or a second available value, such as one (1), indicating that the current block is partitioned using a horizontally oriented partition type other than the horizontal partition type.

[0193] Signaling the block partition symbols with contextual omission (at 1040) includes determining whether partitioning the current block in accordance with the second available value, such as one (1), of the current symbol, wherein the value of the current symbol is thefirst available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0194] For example, the current block may be a 64x64 block, the maximum block partition elongation may be two (2), and the encoder may determine that partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of four (4), eight (8) or sixteen (16).

[0195] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the extended-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation, omitting, skipping, avoiding, or excluding, signaling, or otherwise including, data indicating the value of the current symbol in the encoded bitstream.

[0196] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the extended-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is less than or equal to the maximum block partition elongation, signaling, or otherwise including, data indicating the value of the current symbol (e.g., the extended-partition symbol) in the encoded bitstream.

[0197] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, the value of the current symbol is the second available value (1), signaling, or otherwise including, data indicating the value of the current symbol (e.g., the extended-partition symbol) in the encoded bitstream.

[0198] In some implementations, on a condition that, or in response to a determination that, the value of the extended-partition symbol, flag, or token is the first available value (0), indicating that the current block is partitioned using the horizontal partition type, signaling the block partition symbols with contextual omission (at 1040) is otherwise omitted, skipped,or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the horizontal partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 1060) from signaling the block partition symbols with contextual omission (at 1040) to obtaining the current block (at 1020).

[0199] In some implementations, the value of the extended-partition symbol, flag, or token is the second available value, such as one (1), indicating that the current block is partitioned using a horizontally oriented partition type other than the horizontal partition type, and, subsequent to obtaining the value of the sequentially fourth symbol, signaling the block partition symbols with contextual omission (at 1040) includes identifying a sequentially fifth symbol, such as the four- way-partition symbol, flag, or token, from the sequence of block partition symbols as the current symbol and obtaining a value of the current symbol. The value of the four- way-partition symbol, flag, or token may be a first available value, such as zero (0), indicating that the current block is partitioned using the horizontal-H partition type, or a second available value, such as one (1), indicating that the current block is partitioned using an uneven horizontal partition type.

[0200] Signaling the block partition symbols with contextual omission (at 1040) includes determining whether partitioning the current block in accordance with the second available value, such as one (1), of the current symbol, wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0201] For example, the current block may be a 64x32 block, the maximum block partition elongation may be eight (8), and the encoder may determine that partitioning the current block in accordance with the second available value (1) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of sixteen (16).

[0202] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the four-way-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation, omitting, skipping,avoiding, or excluding, signaling, or otherwise including, data indicating the value of the current symbol in the encoded bitstream.

[0203] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the four-way-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is less than or equal to the maximum block partition elongation, signaling, or otherwise including, data indicating the value of the current symbol (e.g., the four-way-partition symbol) in the encoded bitstream.

[0204] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, the value of the current symbol is the second available value (1), signaling, or otherwise including, data indicating the value of the current symbol (e.g., the four-way-partition symbol) in the encoded bitstream.

[0205] In some implementations, on a condition that, or in response to a determination that, the value of the four-way-partition symbol, flag, or token is the first available value (0), indicating that the current block is partitioned using the horizontal-H partition type, signaling the block partition symbols with contextual omission (at 1040) is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the horizontal-H partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 1060) from signaling the block partition symbols with contextual omission (at 1040) to obtaining the current block (at 1020).

[0206] In some implementations, the value of the four-way-partition symbol, flag, or token is the second available value, such as one (1), indicating that the current block is partitioned using an uneven horizontal partition type, and, subsequent to obtaining the value of the sequentially fifth symbol, signaling the block partition symbols with contextual omission (at 1040) includes identifying a sequentially sixth symbol, such as the A-or-B-partition, flag, or token, from the sequence of block partition symbols as the current symbol and obtaining a value of the current symbol. The value of the A-or-B -partition, flag, or token may be a first available value, such as zero (0), indicating that the current block is partitioned using the first uneven horizontal partition type, or a second available value, such as one (1),indicating that the current block is partitioned using the second uneven horizontal partition type.

[0207] Signaling the block partition symbols with contextual omission (at 1040) includes signaling, or otherwise including, data indicating the value of the current symbol (e.g., the A-or-B -partition) in the encoded bitstream.

[0208] One or more of the subblocks obtained by partitioning the current block in accordance with an uneven horizontal partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 1060) from signaling the block partition symbols with contextual omission (at 1040) to obtaining the current block (at 1020).

[0209] In some implementations, the value of the rectangular-type-partition symbol, flag, or token is the second available value, such as one (1), indicating that the current block is partitioned using a vertically oriented partition type, and, subsequent to obtaining the value of the sequentially third symbol, signaling the block partition symbols with contextual omission (at 1040) includes identifying the sequentially fourth symbol, such as the extended-partition symbol, flag, or token, from the sequence of block partition symbols as the current symbol and obtaining a value of the current symbol. The value of the extended-partition symbol, flag, or token may be the first available value, such as zero (0), indicating that the current block is partitioned using the vertical partition type, or the second available value, such as one (1), indicating that the current block is partitioned using a vertically oriented partition type other than the vertical partition type.

[0210] Signaling the block partition symbols with contextual omission (at 1040) includes determining whether partitioning the current block in accordance with the second available value, such as one (1), of the current symbol, wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0211] For example, the current block may be a 64x64 block, the maximum block partition elongation may be two (2), and the encoder may determine that partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of four (4), eight (8) or sixteen (16).

[0212] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the extended-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation, omitting, skipping, avoiding, or excluding, signaling, or otherwise including, data indicating the value of the current symbol in the encoded bitstream.

[0213] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the extended-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is less than or equal to the maximum block partition elongation, signaling, or otherwise including, data indicating the value of the current symbol (e.g., the extended-partition symbol) in the encoded bitstream.

[0214] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, the value of the current symbol is the second available value (1), signaling, or otherwise including, data indicating the value of the current symbol (e.g., the extended-partition symbol) in the encoded bitstream.

[0215] In some implementations, on a condition that, or in response to a determination that, the value of the extended-partition symbol, flag, or token is the first available value (0), indicating that the current block is partitioned using the vertical partition type, signaling the block partition symbols with contextual omission (at 1040) is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the vertical partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 1060) from signaling the block partition symbols with contextual omission (at 1040) to obtaining the current block (at 1020).

[0216] In some implementations, the value of the extended-partition symbol, flag, or token is the second available value, such as one (1), indicating that the current block is partitioned using a vertically oriented partition type other than the vertical partition type, and, subsequent to obtaining the value of the sequentially fourth symbol, signaling the blockpartition symbols with contextual omission (at 1040) includes identifying the sequentially fifth symbol, such as the four- way-partition symbol, flag, or token, from the sequence of block partition symbols as the current symbol and obtaining a value of the current symbol. The value of the four- way-partition symbol, flag, or token may be the first available value, such as zero (0), indicating that the current block is partitioned using the vertical-H partition type, or the second available value, such as one (1), indicating that the current block is partitioned using an uneven vertical partition type.

[0217] Signaling the block partition symbols with contextual omission (at 1040) includes determining whether partitioning the current block in accordance with the second available value, such as one (1), of the current symbol, wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation.

[0218] For example, the current block may be a 32x64 block, the maximum block partition elongation may be eight (8), and the encoder may determine that partitioning the current block in accordance with the second available value (1) of the current symbol corresponds with a block partition elongation, or block partition elongations, that is, or are, greater than the maximum block partition elongation, such as coding block sizes having a block partition elongation of sixteen (16).

[0219] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the four-way-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is greater than the maximum block partition elongation, omitting, skipping, avoiding, or excluding, signaling, or otherwise including, data indicating the value of the current symbol in the encoded bitstream.

[0220] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, partitioning the current block in accordance with the second available value (1) of the current symbol, wherein the current symbol is the four-way-partition symbol and wherein the value of the current symbol is the first available value (0), corresponds with a block partition elongation that is less than or equal to the maximum block partition elongation, signaling, or otherwise including, data indicating the value of the current symbol (e.g., the four-way-partition symbol) in the encoded bitstream.

[0221] In some implementations, signaling the block partition symbols with contextual omission (at 1040) includes, on a condition that, or in response to a determination that, the value of the current symbol is the second available value (1), signaling, or otherwise including, data indicating the value of the current symbol (e.g., the four-way-partition symbol) in the encoded bitstream.

[0222] In some implementations, on a condition that, or in response to a determination that, the value of the four-way-partition symbol, flag, or token is the first available value (0), indicating that the current block is partitioned using the vertical-H partition type, signaling the block partition symbols with contextual omission (at 1040) is otherwise omitted, skipped, or excluded for the current block. One or more of the subblocks obtained by partitioning the current block in accordance with the vertical-H partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 1060) from signaling the block partition symbols with contextual omission (at 1040) to obtaining the current block (at 1020).

[0223] In some implementations, the value of the four-way-partition symbol, flag, or token is the second available value, such as one (1), indicating that the current block is partitioned using an uneven vertical partition type, and, subsequent to obtaining the value of the sequentially fifth symbol, signaling the block partition symbols with contextual omission (at 1040) includes identifying a sequentially sixth symbol, such as the A-or-B -partition, flag, or token, from the sequence of block partition symbols as the current symbol and obtaining a value of the current symbol. The value of the A-or-B -partition, flag, or token may be the first available value, such as zero (0), indicating that the current block is partitioned using the first uneven vertical partition type, or the second available value, such as one (1), indicating that the current block is partitioned using the second uneven vertical partition type.

[0224] Signaling the block partition symbols with contextual omission (at 1040) includes signaling, or otherwise including, data indicating the value of the current symbol (e.g., the A-or-B -partition) in the encoded bitstream.

[0225] One or more of the subblocks obtained by partitioning the current block in accordance with an uneven vertical partition type may be identified, such as iteratively, as the current block and partitioned, such as recursively, as indicated by the broken directional line (at 1060) from signaling the block partition symbols with contextual omission (at 1040) to obtaining the current block (at 1020).

[0226] The encoded bitstream is output (at 1050).

[0227] The encoded bitstream output as shown (at 1050) in FIG. 10, or decoded as described with respect to FIG. 9, may be a non-transitory computer-readable medium having stored thereon an encoded bitstream, which may include encoded block partition aspect ratio constraint data indicating a maximum block partition elongation and encoded data for a current block of a current frame. The encoded data may include an encoded value of a sequentially first symbol from a sequence of block partition symbols, wherein the current block is partitioned in accordance with the sequence of block partition symbols, and wherein the encoded value indicates partitioning of the current block, wherein data encoding a value of a second symbol from the sequence of block partition symbols is absent from the encoded bitstream.

[0228] In some implementations, the encoded data includes an encoded value of a third symbol from the sequence of block partition symbols subsequent to the second symbol in the sequence of block partition symbols.

[0229] In some implementations, the encoded bitstream includes header data for a sequence of frames, wherein the sequence of frames includes the current frame, and wherein the header data includes the encoded block partition aspect ratio constraint data.

[0230] In some implementations, the encoded bitstream includes header data for the current frame, wherein the header data includes the encoded block partition aspect ratio constraint data.

[0231] In some implementations, the encoded bitstream includes header data for a current tile of the current frame, wherein the header data includes the encoded block partition aspect ratio constraint data.

[0232] In some implementations, the encoded block partition aspect ratio constraint data includes an encoded index value corresponding to the maximum block partition elongation in an index of available maximum block partition elongations.

[0233] As used herein, the terms “optimal”, “optimized”, “optimization”, or other forms thereof, are relative to a respective context and are not indicative of absolute theoretic optimization unless expressly specified herein.

[0234] As used herein, the term “set” indicates a distinguishable collection or grouping of zero or more distinct elements or members that may be represented as a one-dimensional array or vector, except as expressly described herein or otherwise clear from context.

[0235] The words “example” or “exemplary” are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” or “exemplary” not necessarily to be construed as preferred or advantageous over other aspectsor designs. Rather, use of the words “example” or “exemplary” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term “an embodiment” or “one embodiment” or “an implementation” or “one implementation” throughout is not intended to mean the same embodiment or implementation unless described as such. As used herein, the terms “determine” and “identify”, or any variations thereof, includes selecting, ascertaining, computing, looking up, receiving, determining, establishing, obtaining, or otherwise identifying or determining in any manner whatsoever using one or more of the devices shown in FIG. 1.

[0236] Further, for simplicity of explanation, although the figures and descriptions herein may include sequences or series of steps or stages, elements of the methods disclosed herein can occur in various orders and / or concurrently. Additionally, elements of the methods disclosed herein may occur with other elements not explicitly presented and described herein. Furthermore, one or more elements of the methods described herein may be omitted, avoided, or excluded from implementations of methods in accordance with the disclosed subject matter.

[0237] The implementations of the transmitting computing and communication device 100 A and / or the receiving computing and communication device 100B (and the algorithms, methods, instructions, etc. stored thereon and / or executed thereby) can be realized in hardware, software, or any combination thereof. The hardware can include, for example, computers, intellectual property (IP) cores, application-specific integrated circuits (ASICs), programmable logic arrays, optical processors, programmable logic controllers, microcode, microcontrollers, servers, microprocessors, digital signal processors or any other suitable circuit. In the claims, the term “processor” should be understood as encompassing any of the foregoing hardware, either singly or in combination. The terms “signal” and “data” are used interchangeably. Further, portions of the transmitting computing and communication device 100A and the receiving computing and communication device 100B do not necessarily have to be implemented in the same manner.

[0238] Further, in one implementation, for example, the transmitting computing and communication device 100 A or the receiving computing and communication device 100B can be implemented using a computer program that, when executed, carries out any of the respective methods, algorithms and / or instructions described herein. In addition, or alternatively, for example, a special purpose computer / processor can be utilized which can contain specialized hardware for carrying out any of the methods, algorithms, or instructions described herein.

[0239] The transmitting computing and communication device 100 A and receiving computing and communication device 100B can, for example, be implemented on computers in a real-time video system. Alternatively, the transmitting computing and communication device 100 A can be implemented on a server and the receiving computing and communication device 100B can be implemented on a device separate from the server, such as a hand-held communications device. In this instance, the transmitting computing and communication device 100 A can encode content using an encoder 400 into an encoded video signal and transmit the encoded video signal to the communications device. In turn, the communications device can then decode the encoded video signal using a decoder 500.Alternatively, the communications device can decode content stored locally on the communications device, for example, content that was not transmitted by the transmitting computing and communication device 100A. Other suitable transmitting computing and communication device 100 A and receiving computing and communication device 100B implementation schemes are available. For example, the receiving computing and communication device 100B can be a generally stationary personal computer rather than a portable communications device and / or a device including an encoder 400 may also include a decoder 500.

[0240] Further, all or a portion of implementations can take the form of a computer program product accessible from, for example, a tangible computer-usable or computer-readable medium. A computer-usable or computer-readable medium can be any device that can, for example, tangibly contain, store, communicate, or transport the program for use by or in connection with any processor. The medium can be, for example, an electronic, magnetic, optical, electromagnetic, or a semiconductor device. Other suitable mediums are also available.

[0241] It will be appreciated that aspects can be implemented in any convenient form. For example, aspects may be implemented by appropriate computer programs which may be carried on appropriate carrier media which may be tangible carrier media (e.g. disks) orintangible carrier media (e.g. communications signals). Aspects may also be implemented using suitable apparatus which may take the form of programmable computers running computer programs arranged to implement the methods and / or techniques disclosed herein. Aspects can be combined such that features described in the context of one aspect may be implemented in another aspect.

[0242] The above-described implementations have been described in order to allow easy understanding of the application are not limiting. On the contrary, the application covers various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structure as is permitted under the law.

Claims

CLAIMSWhat is claimed is:

1. A method comprising :accessing, from an encoded bitstream, block partition aspect ratio constraint data indicating a maximum block partition elongation;obtaining reconstructed block data for a current block of a current frame of a sequence of frames, wherein obtaining the reconstructed block data includes:obtaining a sequence of block partition symbols for the current block, wherein obtaining the sequence of block partition symbols includes:in response to determining that partitioning the current block in accordance with a first available value of a current symbol from the sequence of block partition symbols corresponds with a block partition elongation that is greater than the maximum block partition elongation, obtaining, as a value of the current symbol, a second available value of the current symbol, wherein data indicating a value of the current symbol is absent from the encoded bitstream; andpartitioning the current block in accordance with the sequence of block partition symbols;including the reconstructed block data in reconstructed frame data for the current frame; andoutputting the reconstructed frame data.

2. The method of claim 1, wherein obtaining the value of the current symbol includes obtaining the value of the current symbol subsequent to obtaining a value of a sequentially first symbol from the sequence of block partition symbols by entropy decoding the value of the sequentially first symbol from the encoded bitstream.

3. The method of claim 1, wherein accessing the block partition aspect ratio constraint data includes accessing the block partition aspect ratio constraint data from a sequence header for the sequence of frames.

4. The method of claim 1, wherein accessing the block partition aspect ratio constraint data includes accessing the block partition aspect ratio constraint data from a frame header for the current frame.

5. The method of claim 1, wherein accessing the block partition aspect ratio constraint data includes accessing the block partition aspect ratio constraint data from a tile header for a tile that includes the current block.

6. The method of claim 1, wherein accessing the block partition aspect ratio constraint data includes accessing, from the encoded bitstream, an index value corresponding to the maximum block partition elongation in an index of available maximum block partition elongations.

7. The method of claim 1, wherein obtaining the sequence of block partition symbols includes:subsequent to obtaining the value of the current symbol, obtaining a value of another symbol from the sequence of block partition symbols subsequent to the current symbol in the sequence of block partition symbols.

8. An apparatus comprising:a non-transitory computer-readable medium; anda processor configured to execute instructions stored on the non-transitory computer-readable medium to:access, from an encoded bitstream, block partition aspect ratio constraint data indicating a maximum block partition elongation;obtain reconstructed block data for a current block of a current frame of a sequence of frames, wherein, to obtain the reconstructed block data, the processor is configured to execute the instructions to:obtain a sequence of block partition symbols for the current block, wherein, to obtain the sequence of block partition symbols, the processor is configured to execute the instructions to:in response to a determination that partitioning the current block in accordance with a first available value of a current symbol from the sequence of block partition symbols corresponds with a blockpartition elongation that is greater than the maximum block partition elongation, obtain, as a value of the current symbol, a second available value of the current symbol, wherein data indicating the value of the current symbol is absent from the encoded bitstream; andpartition the current block in accordance with the sequence of block partition symbols;include the reconstructed block data in reconstructed frame data for the current frame; andoutput the reconstructed frame data.

9. The apparatus of claim 8, wherein, to obtain the sequence of block partition symbols, the processor is configured to execute the instructions to:obtain a value of a sequentially first symbol from the sequence of block partition symbols, wherein, to obtain the value of the sequentially first symbol, the processor is configured to execute the instructions to entropy decode the value of the sequentially first symbol from the encoded bitstream; andobtain the value of the current symbol in response to a determination that the value of the sequentially first symbol is a first available value of the sequentially first symbol.

10. The apparatus of claim 8, wherein, to access the block partition aspect ratio constraint data, the processor is configured to execute the instructions to access the block partition aspect ratio constraint data from a sequence header for the sequence of frames.

11. The apparatus of claim 8, wherein, to access the block partition aspect ratio constraint data, the processor is configured to execute the instructions to access the block partition aspect ratio constraint data from a frame header for the current frame.

12. The apparatus of claim 8, wherein, to access the block partition aspect ratio constraint data, the processor is configured to execute the instructions to access the block partition aspect ratio constraint data from a tile header for a tile that includes the current block.

13. The apparatus of claim 8, wherein, to access the block partition aspect ratio constraint data, the processor is configured to execute the instructions to access, from the encodedbitstream, an index value corresponding to the maximum block partition elongation in an index of available maximum block partition elongations.

14. The apparatus of claim 8, wherein, to obtain the sequence of block partition symbols, the processor is configured to execute the instructions to:obtain a value of another symbol from the sequence of block partition symbols subsequent to the current symbol in the sequence of block partition symbols.

15. A non-transitory computer-readable medium having stored thereon an encoded bitstream for decoding by a decoder, the encoded bitstream comprising:encoded block partition aspect ratio constraint data indicating a maximum block partition elongation; andencoded data for a current block of a current frame, wherein the encoded data includes:an encoded value of a sequentially first symbol from a sequence of block partition symbols, wherein the current block is partitioned in accordance with the sequence of block partition symbols, and wherein the encoded value indicates partitioning of the current block, wherein data encoding a value of a second symbol from the sequence of block partition symbols is absent from the encoded bitstream.

16. The non-transitory computer- readable medium of claim 15, wherein the encoded data includes:an encoded value of a third symbol from the sequence of block partition symbols subsequent to the second symbol in the sequence of block partition symbols.

17. The non-transitory computer- readable medium of claim 15, wherein the encoded bitstream includes:header data for a sequence of frames, wherein the sequence of frames includes the current frame, and wherein the header data includes the encoded block partition aspect ratio constraint data.

18. The non-transitory computer- readable medium of claim 15, wherein the encoded bitstream includes:header data for the current frame, wherein the header data includes the encoded block partition aspect ratio constraint data.

19. The non-transitory computer- readable medium of claim 15, wherein the encoded bitstream includes:header data for a current tile of the current frame, wherein the header data includes the encoded block partition aspect ratio constraint data.

20. The non-transitory computer- readable medium of claim 15, wherein the encoded block partition aspect ratio constraint data includes an encoded index value corresponding to the maximum block partition elongation in an index of available maximum block partition elongations.

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