Elastic intra block prediction

Abstract

Decoding using elastic intra block prediction includes decoding an encoded bitstream by accessing encoded block data for a current block of a current frame, accessing data indicating the use of elastic intra block prediction mode for decoding the current block, obtaining, for decoding the current block using an elastic intra block prediction model, elastic intra block prediction model parameters, obtaining a predicted value of a current pixel from the current block using the elastic intra block prediction model, the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from a previously decoded reference block in the current frame that differs from one or more previously decoded blocks adjacent to the current block, obtaining decoded block data for the current block using the predicted value, obtaining reconstructed frame data for the current frame using the decoded block data, and outputting the reconstructed frame data.

Description

Atty. Doc. No. GOGL-2237-A-WO PATENT ELASTIC INTRA BLOCK PREDICTION CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to and the benefit of U.S. Provisional Application Patent Serial No. 63 / 611,397, filed December 18, 2023, 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 elastic intra block prediction.

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

[0005] An aspect is a method for encoding using elastic intra block prediction. Encoding using elastic intra block prediction includes generating an encoded bitstream by encoding input video data. Encoding the input video data includes obtaining a current frame from the input video data, obtaining a current block from the current frame, obtaining, for encoding the current block using an elastic intra block prediction model, elastic intra block prediction model parameters, obtaining a predicted value of a current pixel from the current block using the elastic intra block prediction model, the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from a previously decoded reference block in the current frame that differs from one or more previously decoded blocks adjacent to the current block, obtaining encoded block data for the current block using the predicted value, including, in the encoded bitstream, the encoded block data, and including, in the encodedbitstream, and data indicating the use of elastic intra block prediction mode for the current block. Encoding using elastic intra block prediction includes outputting the encoded bitstream.

[0006] An aspect is an apparatus for encoding using elastic intra block prediction. The apparatus includes a non-transitory computer readable medium, and a processor configured to execute instructions stored on the non-transitory computer readable medium to generate an encoded bitstream, wherein, to generate the encoded bitstream, the processor is configured to execute the instructions to encode input video data. To encode the input video data, the processor is configured to execute the instructions to obtain a current frame from the input video data, obtain a current block from the current frame, obtain, for encoding the current block using an elastic intra block prediction model, elastic intra block prediction model parameters, obtain a predicted value of a current pixel from the current block using the elastic intra block prediction model, the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from a previously decoded reference block in the current frame that differs from one or more previously decoded blocks adjacent to the current block, obtain encoded block data for the current block using the predicted value, include, in the encoded bitstream, the encoded block data, and include, in the encoded bitstream, data indicating the use of elastic intra block prediction mode for the current block. To encode the input video data, the processor is configured to execute the instructions to output the encoded bitstream.

[0007] An aspect is a bitstream that includes data encoded using elastic intra block prediction.

[0008] An aspect is a method for decoding using elastic intra block prediction. Decoding using elastic intra block prediction includes generating reconstructed video data by decoding an encoded bitstream and outputting the reconstructed video data. Decoding the encoded bitstream includes accessing, from the encoded bitstream, encoded block data for a current block of a current frame, accessing, from the encoded bitstream, data indicating use of elastic intra block prediction mode for decoding the current block, obtaining, for decoding the current block using an elastic intra block prediction model, elastic intra block prediction model parameters, obtaining a predicted value of a current pixel from the current block using the elastic intra block prediction model, the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from a previously decoded reference block in the current frame that differs from one or more previously decoded blocks adjacent to the current block, obtaining decoded block data for the current block using the predicted value,obtaining reconstructed frame data for the current frame using the decoded block data, and including the reconstructed frame data in the reconstructed video data.

[0009] An aspect is an apparatus for decoding using elastic intra block prediction. The apparatus includes a non-transitory computer readable medium, and a processor configured to execute instructions stored on the non-transitory computer readable medium to generate reconstructed video data wherein, to generate the reconstructed video data, the processor is configured to execute the instructions to decode an encoded bitstream and output the reconstructed video data. To decode the encoded bitstream, the processor is configured to execute the instructions to access, from the encoded bitstream, encoded block data for a current block of a current frame, access, from the encoded bitstream, data indicating the use of elastic intra block prediction mode for decoding the current block, obtain, for decoding the current block using an elastic intra block prediction model, elastic intra block prediction model parameters, obtain a predicted value of a current pixel from the current block using the elastic intra block prediction model, the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from a previously decoded reference block in the current frame that differs from one or more previously decoded blocks adjacent to the current block, obtain decoded block data for the current block using the predicted value, and obtain reconstructed frame data for the current frame using the decoded

[0010] An aspect is a bitstream that includes data for decoding using elastic intra block prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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.

[0012] FIG. 1 is a diagram of a computing device in accordance with implementations of this disclosure.

[0013] FIG. 2 is a diagram of a computing and communications system in accordance with implementations of this disclosure.

[0014] FIG. 3 is a diagram of a video stream for use in encoding and decoding in accordance with implementations of this disclosure.

[0015] FIG. 4 is a block diagram of an encoder in accordance with implementations of this disclosure.

[0016] FIG. 5 is a block diagram of a decoder in accordance with implementations of thisdisclosure.

[0017] FIG. 6 is a block diagram of a representation of a portion of a frame in accordance with implementations of this disclosure.

[0018] FIG. 7 is a block diagram of an example of image elements for coding using intra prediction in accordance with implementations of this disclosure.

[0019] FIG. 8 is a flowchart diagram of an example of encoding using elastic intra block prediction 800 in accordance with implementations of this disclosure.

[0020] FIG. 9 is a block diagram of an example of image elements for coding using elastic intra block prediction in accordance with implementations of this disclosure.

[0021] FIG. 10 is a flowchart diagram of an example of decoding using elastic intra block prediction in accordance with implementations of this disclosure. DETAILED DESCRIPTION

[0022] 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 inter- prediction or intra-prediction may be limited.

[0023] The encoding and decoding using elastic intra block prediction described herein improves on video coding techniques, or codecs, by coding blocks using intra block copy mode prediction using elastic intra block copy models, such linear models and non-linearmodels, obtaining model parameters using matched reference templates, and, in some implementations, omitting signaling model parameters, expressly signaling model parameters, differentially signaling model parameters, or differentially signaling model reference parameters.

[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 can include any non-transitory computer-usable or 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, an application-specific integrated circuits (ASICs), or any type of non-transitory media suitable for storing electronic information, or any combination thereof.

[0027] Although shown 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 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 withthe 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 light- sensing device, a motion sensing device, or a combination thereof. For example, 100the 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 (Li-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 be operatively 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 100A, 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 100A, 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 100A, 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 100A and the computing and communication device 100B are described as user devices, and the computing and communication device 100C is described 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 100A 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 100A, 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 100A, 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), widearea 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 100A, 100B, 100C can communicate with each other via the network 220 using one or more a wired or wireless communication links, 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 100A 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 210B 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, 210B 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 100A, 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 100A 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 100A 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 16×16 group of pixels, an 8×8 group of pixels, an 8×16 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 someimplementations, 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, a reconstruction 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-Loève 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., 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 todecode 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 zero- run 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 in FIG. 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, a reconstruction 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 64×64 blocks 610, in two rows and two columns in a matrix or Cartesian plane. In some implementations, a 64×64 block may be a maximum coding unit, N=64. Each 64×64 block may include four 32×32 blocks 620. Each 32×32 block may include four 16×16 blocks 630. Each 16×16 block may include four 8×8 blocks 640. Each 8×8 block 640 may include four 4×4 blocks 650. Each 4×4 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 16×16 pixel block as shown, mayinclude 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 16×16 luminance pixels 662 and each chrominance block 670, 680 may include 8×8 chrominance pixels 690 as shown. Although one arrangement of blocks is shown, any arrangement may be used. Although FIG. 6 shows N×N blocks, in some implementations, N×M blocks may be used. For example, 32×64 blocks, 64×32 blocks, 16×32 blocks, 32×16 blocks, or any other size blocks may be used. In some implementations, N×2N blocks, 2N×N 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 raster- scan order, wherein blocks may be identified and processed starting with a block in the upper left corner 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 64×64 block in the top row and left column of a frame may be the first block coded and the 64×64 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 64×64 block in the left column of the second row may be coded after the 64×64 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 64×64 block shown in the bottom left corner of the portion of the frame shown in FIG. 6, may be coded using quad-tree coding wherein the top left 32×32 block may be coded, then the top right 32×32 block may be coded, then the bottom left 32×32 block may be coded, and then the bottom right 32×32 block may be coded. Each 32×32 block may be coded using quad-tree coding wherein the top left 16×16 block may be coded, then the top right 16×16 block may be coded, then the bottom left 16×16 block may be coded, and then the bottom right 16×16 block may be coded. Each 16×16 block may be coded using quad-tree coding wherein the top left 8×8 block may be coded, then the top right 8×8 block may be coded, then the bottom left 8×8 block may be coded, and then the bottom right 8×8 block may be coded. Each 8×8 block may be coded using quad-tree coding wherein the top left 4×4 block may be coded, then the top right 4×4 block may be coded, then the bottom left 4×4 block may be coded, and then the bottom right 4×4 block may be coded. In someimplementations, 8×8 blocks may be omitted for a 16×16 block, and the 16×16 block may be coded using quad-tree coding wherein the top left 4×4 block may be coded, then the other 4×4 blocks in the 16×16 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 16×16 block of pixels, and by two lower resolution chrominance components, each of which represents the portion of the frame as an 8×8 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 in memory, 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 CartesianSimilarly, 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 one- dimensional 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 cornerof a block in the top left corner 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 64×64 coding unit may include rectangular size prediction partitions ranging in sizes from 4×4 to 64×64, such as 4×4, 4×8, 8×4, 8×8, 8×16, 16×8, 16×16, 16×32, 32×16, 32×32, 32×64, 64×32, or 64×64. 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 64×64 as shown, or to partition the block into multiple prediction partitions, which may correspond with the sub-blocks, such as the 32×32 blocks 620 the 16×16 blocks 630, or the 8×8 blocks 640, as shown, and may include determining whether to partition into one or more smaller prediction partitions. For example, a 64×64 block may be partitioned into four 32×32 prediction partitions. Three of the four 32×32 prediction partitions may be encoded as 32×32 prediction partitions and the fourth 32×32 prediction partition may be further partitioned into four 16×16 prediction partitions. Three of the four 16×16 prediction partitions may be encoded as 16×16 prediction partitions and the fourth 16×16 prediction partition may be further partitioned into four 8×8 prediction partitions, each of which may be encoded as an 8×8 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 the compression efficiency. For example, a video coder may evaluate each candidate prediction coding mode to identify the optimal prediction coding mode, which may be, forexample, the prediction coding mode that minimizes an error metric, such as a rate-distortion cost, for the current block. In some implementations, the complexity 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 16×16, 8×8, and 4×4, the error metric associated with each block size may be in descending order, and additional candidate block sizes, such as 4×8 and 8×4 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 64×64 block and may be transformed without partitioning using a 64×64 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 64×64 residual block may be transform partitioned using a uniform transform partitioning scheme including four 32×32 transform blocks, using a uniform transform partitioning scheme including sixteen 16×16 transform blocks, using a uniform transform partitioning scheme including sixty-four 8×8 transform blocks, or using a uniform transform partitioning scheme including 2564×4 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 64×64 residual block, and multiform transform partition coding may include determining whether to code the current 64×64 residual block using a 64×64 transform or to code the 64×64 residual block by partitioning the 64×64 residual block into partitions, such as four 32×32 blocks 620, and multiform transform partition coding each partition. In someimplementations, determining whether to transform partition the current block may be based on 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 image elements for coding using intra prediction 700 in accordance with implementations of this disclosure, such as decoding using intra prediction or encoding using intra prediction.

[0079] FIG. 7 shows a current frame 710 including a first block 720 and a second block 730. Other previously coded blocks, and blocks to be subsequently coded, in the current frame 710 are omitted from FIG. 7 for simplicity.

[0080] The pixels of a block, such as the first block 720 and the second block 730, may be referenced using Cartesian coordinates relative to the respective block.

[0081] As shown, the first block 720 is coded using spatial, such as directional, intra prediction using values of previously reconstructed pixels 740, which are local neighbor pixels, shown with a stippled background, from blocks adjacent, such as immediately adjacent, to the first block 720, such as from a previously reconstructed row immediately above the first block 720 and from a previously reconstructed column immediately to the left of the first block 720. One or more of the previously reconstructed pixels 740, such as the previously reconstructed pixels in the column to the left of the first block 720 and below the first block 720, may be projected pixels. The spatial intra prediction mode used to code the first block 720 is selected from among multiple available spatial intra prediction modes, such as by selecting a most optimal spatial intra prediction mode using rate-distortion optimization. For example, in a DC spatial intra prediction mode, averaged pixel values of the previously reconstructed pixels 740 above and to the left of the first block 720 are used as a predicted value for the first block 720. In another example, in a vertical spatial intra prediction mode, pixel values of the previously reconstructed pixels 740 above the first block 720 are used as predicted values of the first block 720.

[0082] As shown in FIG. 7, the first block 720 is coded, such as reconstructed, prior to coding the second block 730 and is available as an intra block copy reference block for coding the second block 730.

[0083] As shown in FIG. 7, the second block 730 is coded using intra block copy mode, wherein the reconstructed pixels of the first block 720 are used as the prediction of the second block 730, as indicated by the broken directional line (at 750). In intra block copy mode the available reconstructed pixels, or blocks thereof, in the current frame are evaluated, such as searched, to identify a best matching block of available reconstructed pixels which is similarto motion estimation, except as is described herein or as is otherwise clear from context. Although described as reconstructed, the available reference blocks for intra block copy may be partially reconstructed, such as subsequent to decoding and prior to loop filtering. The available intra block copy reference blocks include previously coded, such as reconstructed, blocks from the current frame other than one or more blocks, or superblocks, proximate to, such as immediately adjacent to, the current block, or a current superblock that includes the current block. For example, a superblock immediately above the current superblock may be unavailable as an intra block copy reference block. In another example, a superblock immediately to the left of the current superblock may be unavailable as an intra block copy reference block. In another example, a superblock immediately to the left of the superblock immediately to the left of the current superblock may be unavailable as an intra block copy reference block. A superblock immediately above and to the left of the current superblock may be an available intra block copy reference block. The best matching block of available reconstructed pixels is used as a prediction of the current block. The spatial difference between the current block and the intra block copy reference block is indicated by a block vector, which is similar to a motion vector, except as is described herein or as is otherwise clear from context.

[0084] Obtaining a predicted value ^^^, ^^ for a current pixel of the current block based ona spatially corresponding reference pixel ^^^, ^^ in the reference block using intra block copymode may be expressed as the following: ^^^, ^^ = ^^^, ^^.

[0085] The intra block copy mode is relatively efficient, accurate, or both, with respect to coding content including frequently repeated patterns, such as characters or sharp edges, for example. The intra block copy mode may be less efficient, accurate, or both with respect to non-translational differences between the current block and the reference block.

[0086] FIG. 8 is a flowchart diagram of an example of encoding using elastic intra block prediction 800 in accordance with implementations of this disclosure. Encoding using elastic intra block prediction 800 may be implemented by an encoder, such as the encoder 400 shown in FIG. 4.

[0087] Encoding using elastic intra block prediction 800 includes encoding an input video steam, 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.

[0088] In block-based hybrid video coding, to reduce, or minimize, the resourceutilization, 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.

[0089] Encoding using elastic intra block prediction 800 includes obtaining a current frame (at 810), obtaining a current block (at 820), obtaining a reference block (at 830), obtaining template pixels (at 840), obtaining model parameters (at 850), obtaining a prediction (at 860), obtaining encoded data (at 870), and outputting an encoded bitstream (at 880). Although not shown expressly in FIG. 8, encoding using elastic intra block prediction 800 includes other aspects of video coding.

[0090] Input video data is obtained (at 810). The input video data includes a sequence of frames (input 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.

[0091] The current frame for encoding is obtained (at 810) from the sequence of frames from the input video data. The current frame may be obtained (at 810) 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.

[0092] The current block for encoding is obtained (at 820) from the current frame. The current block may be obtained (at 820) subsequent to encoding one or more other blocks, such as a block sequentially preceding the current block in the current frame, in accordance with a block coding order for coding the current frame, and generating, or otherwise obtaining, a corresponding reconstructed block, or one or more portions thereof.

[0093] Although not shown expressly in FIG. 8, the prediction coding mode for the current block is identified, or determined, as the intra block copy mode using elastic intra block prediction as described herein.

[0094] The reference block, or intra block copy reference block, which is a previously decoded, or reconstructed, block in the current frame, is obtained (at 830). To obtain the reference block the encoder evaluates, or searches, one or more available intra block copy reference blocks of the current frame for a best matching reference block, which is similar to motion estimation, except as is described herein or as is otherwise clear from context. Although described as reconstructed, the available reference blocks for intra block copy may be partially reconstructed, such as subsequent to decoding and prior to loop filtering. Theavailable intra block copy reference blocks include previously coded, such as reconstructed, blocks from the current frame other than one or more blocks, or superblocks, proximate to, such as immediately adjacent to, the current block, or a current superblock that includes the current block. For example, a superblock immediately above the current superblock may be unavailable as an intra block copy reference block. In another example, a superblock immediately to the left of the current superblock may be unavailable as an intra block copy reference block. In another example, a superblock immediately to the left of the superblock immediately to the left of the current superblock may be unavailable as an intra block copy reference block. A superblock immediately above and to the left of the current superblock may be an available intra block copy reference block.

[0095] The encoder obtains template pixels (at 840). Obtaining the template pixels (at 840) includes obtaining previously decoded pixels relative, such as spatially proximate to, the current block (obtained at 820), which may be collectively referred to as a reference template for the current block or may be referred to as current block template pixels (first template pixels). The current block template pixels are obtained from one or more previously decoded blocks spatially adjacent to the current block. Obtaining the template pixels (at 840) includes obtaining previously decoded template pixels relative, such as spatially proximate to, the reference block (obtained at 830), which may be collectively referred to as a reference template for the previously decoded reference block or may be referred to as reference block template pixels (second template pixels). The reference block template pixels are obtained from one or more previously decoded blocks spatially adjacent to the reference block. The size, shape, and orientation, relative to the current block and the reference block respectively, of the reference template for the current block and the reference template for the previously decoded reference block match, and the reference template for the current block and the reference template for the previously decoded reference block may be referred to as matched reference templates. An example of matched reference templates is shown in FIG. 9.

[0096] The encoder obtains, determines, calculates, derives, or generates elastic intra block prediction model parameters (at 850). The elastic intra block prediction model parameters are obtained, determined, calculated, derived, or generated, by parameter fitting, such as by regression, using the current block template pixels and the reference block template pixels. In some implementations, the elastic intra block prediction model parameters are obtained, determined, calculated, derived, or generated, by parameter fitting, such as by regression, using the pixels of the current block and the pixels of the reference block.

[0097] In some implementations, obtaining the elastic intra block prediction modelparameters includes identifying, determining, or selecting an elastic intra block prediction model, such as a linear elastic intra block prediction model (linear model) or a non-linear elastic intra block prediction model (non-linear model).

[0098] To obtain the elastic intra block prediction model parameters for the linear elastic intra block prediction model, the encoder performs linear regression with respect to the current block template pixels and the reference block template pixels.

[0099] To obtain the elastic intra block prediction model parameters for the non-linear elastic intra block prediction model, the encoder performs parameter fitting, such as solves a regression problem, with respect to the current block template pixels and the reference block template pixels. In some implementations, obtain the elastic intra block prediction model parameters for the non-linear elastic intra block prediction model, the encoder performs parameter fitting, such as solves a regression problem, with respect to the pixels of the current block and the pixels of the reference block.

[0100] In some implementations, the encoder obtains preliminary elastic intra block prediction model parameters, such as floating-point values, by performing parameter fitting using the current block template pixels and the reference block template pixels, or the pixels of the current block and the pixels of the reference block, and obtains the elastic intra block prediction model parameters by quantizing the preliminary elastic intra block prediction model parameters to integer values with a defined precision.

[0101] The encoder obtains, determines, or calculates a prediction block (at 860) of predicted pixel values for the current block using the elastic intra block prediction model with the elastic intra block prediction model parameters (obtained at 850) and the reference block (obtained at 830). For a respective current pixel (i, j) of the current block, the elastic intra block prediction model with the elastic intra block prediction model parameters (obtained at850) and a value of a reference pixel ^^^, ^^ from the reference block spatially corresponding,relative to the respective blocks, with the current pixel (i, j), may be used to obtain acorresponding predicted value ^^^, ^^.

[0102] In some a linear elastic intra block prediction model may be usedto obtain the predicted value for the current pixel of the current block based on thespatially corresponding reference pixel ^^^, ^^ in the reference block, a first elastic intra blockprediction model parameter (a), and a second elastic intra block prediction model parameter (b).

[0103] For example, using the linear elastic intra block prediction model, the predictedvalue ^^^, ^^ for the current pixel of the current block may be obtained as a sum of the secondelastic prediction model parameter (b) and a product of multiplying the first elastic intra block prediction model parameter (a) by the spatially corresponding referencepixel ^^^, ^^, which may be expressed as the following:

[0104] ^^ = ^ ∗ ^^^, ^^ + ^.

[0105] In some implementations, a non-linear elastic intra block prediction model may beused. In the non-linear elastic intra block prediction model the predicted value ^^^, ^^ for thecurrent pixel of the current block may be obtained as a function (F) of the reference block (X), which may be expressed as the following:

[0106] ^^^, ^^ = ^^^^.

[0107] For example, the non-linear elastic intra block prediction model may be a seven- parameter non-linear elastic intra block prediction model. The seven-parameter non-linearelastic intra block prediction model may be used to obtain a predicted value ^^^, ^^ for acurrent pixel of the current block based on a spatially corresponding reference pixel ^^^, ^^ inthe reference block, a first elastic intra block prediction model parameter (a), a second elastic intra block prediction model parameter (b), a third elastic intra block prediction model parameter (c), a fourth elastic intra block prediction model parameter (d), a fifth elastic intra block prediction model parameter (e), a sixth elastic intra block prediction model parameter (f), and a seventh elastic intra block prediction model parameter (g).

[0108] For example, using the non-linear elastic intra block prediction model, thepredicted value ^^^,for the current pixel of the current block may be obtained as a sum of aresult of multiplying the first elastic intra block prediction model parameter (a) by the valueof the spatially corresponding reference pixel ^^^, ^^, a result of multiplying the secondelastic intra block prediction model parameter (b) by a value of a pixel ^^^ − 1, ^^immediately to the left of the spatially corresponding reference pixela result ofmultiplying the third elastic intra block prediction model parameter (c) by a pixel^^^ + 1, ^^ immediately to the right of the spatially corresponding reference^^, aresult of multiplying the fourth elastic intra block prediction model parameter (d)of a pixel ^^^, ^ − 1^ immediately above the spatially corresponding reference ^^, aresult of multiplying the fifth elastic intra block prediction model parameter (e) by a value ofa pixel ^^^, ^ + 1^ immediately below the spatially corresponding reference pixel ^^^, ^^, aresult of multiplying the value of the corresponding reference pixel by a result of multiplying the sixth elastic intra block prediction model parameter (f) by the value of the spatiallycorresponding reference pixel ^^^, ^^, and the seventh parameter, which may be expressed asthe following:

[0109] ^^^, ^^ = ^ ∗ ^^^, ^^ + ^ ∗ ^^^ − 1, ^^ + ^ ∗ ^^^ + 1, ^^ + ^ ∗ ^^^, ^ − 1^ + ^ ∗^^^, ^ + 1^ + ^ ∗ ^^^, ^^ ∗ ^^^, ^^ + ^.

[0110] The encoder obtains predicted pixel values for the pixels of the current block, which may be referred to collectively as the prediction, or predicted block, for the current block.

[0111] The encoder obtains encoded data (at 870) for the current block. Obtaining the encoded block data for the current block (at 870) may include obtaining a residual block by subtracting the predicted block from the current input block. Obtaining the encoded block data for the current block (at 870) may include encoding, such as entropy coding, the residual block. Obtaining the encoded block data for the current block (at 870) may include including the encoded block data for the current block in the encoded bitstream. Obtaining the encoded block data for the current block (at 870) may include including data, such as a block vector, or corresponding encoded data, indicating the intra block copy reference block in the encoded bitstream for the current block.

[0112] The encoder may include data, such as a bit, or flag, such as a binary flag, in the encoded bitstream to indicate whether the intra block copy mode using elastic intra block prediction is used for the current block.

[0113] In some implementations, the encoder omits, skips, avoids, or excludes including data indicating the elastic intra block prediction model parameters in the encoded bitstream, or otherwise signaling the elastic intra block prediction model parameters, wherein the elastic intra block prediction model parameters are obtained, by the encoder and, separately, by the decoder, using the matched reference templates as described herein.

[0114] In some implementations, the encoder includes the elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, elastic intra block prediction model parameters, in the encoded bitstream for the current block, such that decoding the current block includes accessing, such as by decoding, the elastic intra block prediction model parameters from the encoded bitstream.

[0115] In some implementations, wherein the encoder includes the elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, elastic intra block prediction model parameters, in the encoded bitstream for the current block, the elastic intra block prediction model parameters are obtained, determined, calculated, derived, orgenerated, (at 850) by parameter fitting, such as by regression, using the pixels of the current block and the pixels of the reference block, and obtaining the template pixels (at 840) may be omitted.

[0116] In some implementations, the encoder omits, skips, avoids, or excludes including the elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, elastic intra block prediction model parameters, in the encoded bitstream, and the encoder includes differential, or delta, elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, differential elastic intra block prediction model parameters, in the encoded bitstream for the current block.

[0117] In some implementations, to obtain the differential elastic intra block prediction model parameters the encoder identifies previously used elastic intra block prediction model parameters, such as previously used elastic intra block prediction model parameters previously used for coding another block in the current frame, and obtains, as the differential elastic intra block prediction model parameters the result of subtracting the previously used elastic intra block prediction model parameters from the elastic intra block prediction model parameters for the current block.

[0118] In some implementations, multiple sets of previously used elastic intra block prediction model parameters may be available for encoding the current block, the sets of previously used elastic intra block prediction model parameters may be indexed, the encoder may identify a set of previously used elastic intra block prediction model parameters, and the corresponding index value, for encoding the current block, and the encoder may include the index value for the set of previously used elastic intra block prediction model parameters used for encoding the current block, or a corresponding encoded, such as entropy coded, index value, in the encoded bitstream for the current block.

[0119] In some implementations, wherein the encoder includes the differential elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, differential elastic intra block prediction model parameters, in the encoded bitstream for the current block, the elastic intra block prediction model parameters are obtained, determined, calculated, derived, or generated, (at 850) by parameter fitting, such as by regression, using the pixels of the current block and the pixels of the reference block, and obtaining the template pixels (at 840) may be omitted.

[0120] In some implementations, the encoder omits, skips, avoids, or excludes including the elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, elastic intra block prediction model parameters, in the encoded bitstream, andthe encoder includes differential elastic intra block prediction model reference parameters, or corresponding encoded, such as entropy coded, differential elastic intra block prediction model reference parameters, in the encoded bitstream for the current block.

[0121] To obtain the differential elastic intra block prediction model reference parameters the encoder uses the elastic intra block prediction model parameters obtained using the matched reference templates as elastic intra block prediction model reference parameters, the encoder obtains, determines, calculates, derives, or generates, (at 850) the elastic intra block prediction model parameters by parameter fitting, such as by regression, using the pixels of the current block and the pixels of the reference block, and the encoder obtains the differential elastic intra block prediction model reference parameters by subtracting the elastic intra block prediction model reference parameters, obtained using the matched reference templates, from the elastic intra block prediction model parameters, obtained using the current block and the prediction block.

[0122] In some implementations, the encoder may include information describing the matched reference templates in the encoded bitstream, which may include information describing a size, such as horizontal size, vertical size, or both, of the matched reference templates, information indicating the orientation or relative location of the matched reference templates, or both.

[0123] The output, compressed, or encoded, bitstream, is output, such as stored or transmitted, such as to a decoder, (at 870).

[0124] FIG. 9 is a block diagram of an example of image elements for coding using elastic intra block prediction 900 in accordance with implementations of this disclosure, such as for the encoding using elastic intra block prediction 800 shown in FIG. 8 or the decoding using elastic intra block prediction 1000 shown in FIG. 10.

[0125] FIG. 9 shows a current frame 910 including a current block 920 and a previously decoded reference block 930. Other previously coded blocks, and blocks to be subsequently coded in the current frame 910 are omitted from FIG. 9 for simplicity.

[0126] The pixels of a block, such as the current block 920 and the previously decoded reference block 930, may be referenced using Cartesian coordinates relative to the respective block.

[0127] The current block 920 includes a current pixel 922 (P) having a horizontal, columnar, location (i) in the current block 920 and a vertical, row, location (j) in the current block 920, such that the location of the current pixel 922 in the current block 920 may be expressed as P(i, j). A predicted value (Y) for the current pixel 922 may be expressed as Y(i,j).

[0128] The current block 920 has a height (H), such as eight pixels, and a width (W), such as eight pixels. Other block sizes may be used.

[0129] FIG. 9 shows current block template pixels 940 for the current block 920, which may be collectively referred to as a reference template for the current block 920. As shown in FIG. 9, the current block template pixels 940 for the current block 920 include pixels from four rows of the current frame 910 immediately above the current block 920, pixels from four columns of the current frame 910 immediately to the left of the current block 920, and pixels from four columns of the current frame 910 and four rows of the current frame 910 immediately above and to the left of the current block 920. The current block template pixels 940 may be previously reconstructed pixels from blocks from the current frame 910 other than the current block 920, which are previously decoded, or reconstructed, blocks immediately adjacent to the current block 920. The current block template pixels 940 are oriented with respect to the current block 920 in accordance with a defined orientation. Other cardinalities and orientations of the current block template pixels 940 may be used. The current block template pixels 940 may be referenced using Cartesian coordinates relative to the current block 920, such as relative to the top-left pixel of the current block 920. For example, the reference pixel at the top-left of the current block template pixels 940 may be expressed as P[i-4, j-4].

[0130] The current block template pixels 940 may be pixels from the current reconstructed frame, such as previously decoded, reconstructed, or both, pixels from the current reconstructed frame. The current block template pixels 940 may be identified in accordance with a defined spatial orientation relative to the current block 920. The current block template pixels 940 may correspond with a causal intra-prediction region for one or more intra- prediction modes for coding the current block 920. The defined orientation may indicate that the current block template pixels 940 are oriented proximate to, such as adjacent to or neighboring, the current block 920 in the current frame 910 or tile. For example, the current block template pixels 940 may include pixels from one or more blocks immediately adjacent above the current block 920, one or more blocks immediately adjacent to the left of the current block 920, one or more blocks immediately adjacent above and to the left of the current block 920, or a combination thereof. Other orientations of current block template pixels 940 relative to the current block 920 in the current frame 910 or tile may be used. Identifying the current block template pixels 940 may be similar to identifying context pixels for intra-prediction, except as is described herein or as is otherwise clear from context. In anexample, the current block template pixels 940 may be the pixels from the four nearest neighboring rows above the current block 920, the pixels from the four nearest neighboring columns to the left of the current block 920, and the pixels from the four nearest neighboring rows and columns above and to the left of the current block 920.

[0131] The reference template for the current block 920 has a height (Th), indicating a number, count, or cardinality (first defined cardinality) of rows of pixels in the reference template for the current block 920. The height (Th) of the reference template for the current block 920 may be the height (H) of the current block 920 plus a defined number, count, or cardinality of rows (I), such that the height (Th) of the reference template for the current block 920 may be expressed as Th = H + I. For example, as shown in FIG. 9, the defined number, count, or cardinality of rows (I) is four (I=4). Other values, such as two, for the defined number, count, or cardinality of rows (I) may be used.

[0132] The reference template for the current block 920 has a width (Tw), indicating a number, count, or cardinality (second defined cardinality) of columns of pixels in the reference template for the current block 920. The width (Tw) of the reference template for the current block 920 may be the width (W) of the current block 920 plus a defined number, count, or cardinality of columns (J), such that the width (Tw) of the reference template for the current block 920 may be expressed as Tw = W + J. For example, as shown in FIG. 9, the defined number, count, or cardinality of columns (J) is four (J=4). Other values, such as two, for the defined number, count, or cardinality of columns (J) may be used.

[0133] In some implementations, the defined number, count, or cardinality of rows (I) may be the defined number, count, or cardinality of columns (J) (I=J). In some implementations, the defined number, count, or cardinality of rows (I) may differ from the defined number, count, or cardinality of columns (J) (I<>J).

[0134] In some implementations, the size, such as the defined number, count, or cardinality of columns (J), the defined number, count, or cardinality of rows (I), or both, of the matched reference templates may be defined, or described, in association with a respective elastic intra block prediction model. For example, the size of the matched reference templates for the linear elastic intra block prediction model may be expressed as Th = H + 2 and Tw = W + 2. In another example, the size of the matched reference templates for the seven-parameter non-linear elastic intra block prediction model may be expressed as Th = H + 4 and Tw = W + 4.

[0135] The previously decoded reference block 930 includes a current reference pixel 932 (X) having a horizontal, columnar, location (i) in the previously decoded reference block 930and a vertical, row, location (j) in the previously decoded reference block 930, such that the location of the current reference pixel 932 in the previously decoded reference block 930 may be expressed as X(i, j).

[0136] The previously decoded reference block 930 has a height (H), such as eight pixels, and a width (W), such as eight pixels. Other block sizes may be used. The size of the previously decoded reference block 930 may match the size of the current block 920.

[0137] FIG. 9 shows previously decoded reference block template pixels 950 for the previously decoded reference block 930, which may be collectively referred to as a reference template for the previously decoded reference block 930. As shown in FIG. 9, the previously decoded reference block template pixels 950 for the previously decoded reference block 930 include pixels from four rows of the current frame 910 immediately above the previously decoded reference block 930, pixels from four columns of the current frame 910 immediately to the left of the previously decoded reference block 930, and pixels from four columns of the current frame 910 and four rows of the current frame 910 immediately above and to the left of the previously decoded reference block 930. The previously decoded reference block template pixels 950 may be previously reconstructed pixels from blocks from the current frame 910 other than the previously decoded reference block 930, which are previously decoded, or reconstructed, blocks immediately adjacent to the previously decoded reference block 930. The previously decoded reference block template pixels 950 are oriented with respect to the previously decoded reference block 930 in accordance with the defined orientation. Other cardinalities and orientations of the previously decoded reference block template pixels 950 may be used. The previously decoded reference block template pixels 950 may be referenced using Cartesian coordinates relative to the previously decoded reference block 930, such as relative to the top-left pixel of the previously decoded reference block 930. For example, the reference pixel at the top-left of the previously decoded reference block template pixels 950 may be expressed as P[i-4, j-4].

[0138] The previously decoded reference block template pixels 950 may be pixels from the current reconstructed frame, such as previously decoded, reconstructed, or both, pixels from the current reconstructed frame. The previously decoded reference block template pixels 950 may be identified in accordance with the defined spatial orientation relative to the previously decoded reference block 930. The previously decoded reference block template pixels 950 may correspond with a causal intra-prediction region for one or more intra- prediction modes for coding the previously decoded reference block 930. The defined orientation may indicate that the previously decoded reference block template pixels 950 areoriented proximate to, such as adjacent to or neighboring, the previously decoded reference block 930 in the current frame 910 or tile. For example, the previously decoded reference block template pixels 950 may include pixels from one or more blocks immediately adjacent above the previously decoded reference block 930, one or more blocks immediately adjacent to the left of the previously decoded reference block 930, one or more blocks immediately adjacent above and to the left of the previously decoded reference block 930, or a combination thereof. Other orientations of previously decoded reference block template pixels 950 relative to the previously decoded reference block 930 in the current frame 910 or tile may be used. Identifying the previously decoded reference block template pixels 950 may be similar to identifying context pixels for intra-prediction, except as is described herein or as is otherwise clear from context. In an example, the previously decoded reference block template pixels 950 may be the pixels from the four nearest neighboring rows above the previously decoded reference block 930, the pixels from the four nearest neighboring columns to the left of the previously decoded reference block 930, and the pixels from the four nearest neighboring rows and columns above and to the left of the previously decoded reference block 930.

[0139] The reference template for the previously decoded reference block 930 has a height (Th), indicating a number, count, or cardinality of rows of pixels in the reference template for the previously decoded reference block 930. The height (Th) of the reference template for the previously decoded reference block 930 may be the height (H) of the previously decoded reference block 930 plus the defined number, count, or cardinality of rows (I), such that the height (Th) of the reference template for the previously decoded reference block 930 may be expressed as Th = H + r.

[0140] The reference template for the previously decoded reference block 930 has a width (Tw), indicating a number, count, or cardinality of columns of pixels in the reference template for the previously decoded reference block 930. The width (Tw) of the reference template for the previously decoded reference block 930 may be the width (W) of the previously decoded reference block 930 plus the defined number, count, or cardinality of columns (J), such that the width (Tw) of the reference template for the previously decoded reference block 930 may be expressed as Tw = W + c.

[0141] The size, shape, and orientation, relative to the current block and the reference block respectively, of the reference template for the current block 920 (current block template pixels 940) and the reference template for the reference template for the previously decoded reference block 930 (previously decoded reference block template pixels 950) match, and thereference template for the current block and the reference template for the previously decoded reference block may be referred to as matched reference templates. The shape of the matched reference templates may be a flipped, or inverted, L-shape region above and to the left of the current block 920 and the previously decoded reference block 930 respectively.

[0142] FIG. 10 is a flowchart diagram of an example of decoding using elastic intra block prediction 1000 in accordance with implementations of this disclosure. Decoding using elastic intra block prediction 1000 may be implemented in a decoder, such as the decoder 500 shown in FIG. 5. Decoding using elastic intra block prediction 1000 includes block-based hybrid video coding as described herein.

[0143] Decoding using elastic intra block prediction 1000 includes generating reconstructed video data 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.

[0144] Decoding the encoded bitstream, or one or more portions thereof, for decoding using elastic intra block prediction 1000, includes obtaining the encoded bitstream (at 1010), accessing encoded block data (at 1020), obtaining a reference block (at 1030), obtaining template pixels (at 1040), obtaining model parameters (at 1050), obtaining a prediction (at 1060), obtaining decoded data (at 1070), and outputting reconstructed video data (at 1080). One or more aspects of decoding using elastic intra block prediction 1000 may be omitted from the description herein for simplicity and brevity.

[0145] The encoded bitstream is obtained (at 1010). 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. Obtaining the encoded bitstream includes identifying a current frame from a current sequence of frames to decode from the encoded bitstream to generate a current reconstructed frame.

[0146] The decoder accesses, such as decodes, encoded block data (at 1020) for a current block of the current frame. The encoded block data for the current block may be obtained (at 1020) subsequent to decoding one or more other blocks, such as a block sequentially preceding the current block in the current frame, in accordance with a block coding order for coding the current frame, and generating, or otherwise obtaining, a corresponding reconstructed block, or one or more portions thereof.

[0147] In some implementations, obtaining the encoded block data for the current block includes obtaining, such as by decoding from the encoded bitstream, or otherwise accessing, data indicating the use of elastic intra block prediction mode for decoding the current block.For example, the decoder may decode a bit, binary value, or flag indicating the use of elastic intra block prediction mode for decoding the current block.

[0148] The reference block, or intra block copy reference block, which is a previously decoded, or reconstructed, block in the current frame, is obtained (at 1030). For example, the decoder may access, such as decode, or otherwise obtain, data, such as a block vector, indicating the reference block from the encoded bitstream, such as from the encoded block data for the current block. Although described as reconstructed, the available reference blocks for intra block copy may be partially reconstructed, such as subsequent to decoding and prior to loop filtering. The available intra block copy reference blocks include previously coded, such as reconstructed, blocks from the current frame other than one or more blocks, or superblocks, proximate to, such as immediately adjacent to, the current block, or a current superblock that includes the current block. For example, a superblock immediately above the current superblock may be unavailable as an intra block copy reference block. In another example, a superblock immediately to the left of the current superblock may be unavailable as an intra block copy reference block. In another example, a superblock immediately to the left of the superblock immediately to the left of the current superblock may be unavailable as an intra block copy reference block. A superblock immediately above and to the left of the current superblock may be an available intra block copy reference block.

[0149] In some implementations, the decoder obtains, such as decodes, or otherwise accesses data, such as a block vector, from the encoded bitstream, such as from the encoded block data for the current block, indicating the reference block, and obtains the reference block, or reference block data, in accordance with the block vector.

[0150] The decoder obtains template pixels (at 1040). Obtaining the template pixels (at 1040) includes obtaining previously decoded pixels relative, such as spatially proximate to, the current block (obtained at 1020), which may be collectively referred to as a reference template for the current block or may be referred to as current block template pixels (first template pixels). The current block template pixels are obtained from one or more previously decoded blocks spatially adjacent to the current block. Obtaining the template pixels (at 1040) includes obtaining previously decoded template pixels relative, such as spatially proximate to, the reference block (obtained at 1030), which may be collectively referred to as a reference template for the previously decoded reference block or may be referred to as reference block template pixels (second template pixels). The reference block template pixels are obtained from one or more previously decoded blocks spatially adjacent to the reference block. The size, shape, and orientation, relative to the current block and the reference blockrespectively, of the reference template for the current block and the reference template for the previously decoded reference block match, and the reference template for the current block and the reference template for the previously decoded reference block may be referred to as matched reference templates. An example of matched reference templates is shown in FIG. 9.

[0151] The decoder obtains, accesses, determines, calculates, derives, or generates elastic intra block prediction model parameters (at 1050) for the current block.

[0152] In some implementations, the decoder omits, skips, avoids, or excludes obtaining, or accessing, data indicating the elastic intra block prediction model parameters from the encoded bitstream, and obtains the elastic intra block prediction model parameters by parameter fitting using the matched reference templates, which is similar to obtaining the elastic intra block prediction model parameters by parameter fitting using the matched reference templates as shown (at 850) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0153] In some implementations, the decoder obtains preliminary elastic intra block prediction model parameters, such as floating-point values, by performing parameter fitting using the current block template pixels and the reference block template pixels, or the pixels of the current block and the pixels of the reference block, and obtains the elastic intra block prediction model parameters by quantizing the preliminary elastic intra block prediction model parameters to integer values with a defined precision.

[0154] In some implementations, the decoder omits, skips, avoids, or excludes obtaining the template pixels (at 1040) and the decoder accesses, such as decodes or otherwise obtains, (at 1050) the elastic intra block prediction model parameters from the encoded bitstream, such as from the encoded block data for the current block.

[0155] In some implementations, the decoder omits, skips, avoids, or excludes obtaining the elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, elastic intra block prediction model parameters, from the encoded bitstream, the decoder omits, skips, avoids, or excludes obtaining the template pixels (at 1040), the decoder accesses, such as decodes or otherwise obtains, differential, or delta, elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, differential elastic intra block prediction model parameters, from the encoded bitstream, such as from the encoded block data for the current block, the decoder identifies previously used elastic intra block prediction model parameters, such as previously used elastic intra block prediction model parameters previously used for coding another block in the current frame, and obtains, as the elastic intra block prediction model parameters for the current block aresult of combining, such as adding, the differential elastic intra block prediction model parameters to previously used elastic intra block prediction model parameters previously used for decoding another block in the current frame.

[0156] In some implementations, multiple sets of previously used elastic intra block prediction model parameters are available for decoding the current block, the sets of previously used elastic intra block prediction model parameters are indexed, the decoder accesses, such as decodes or otherwise obtains, from the encoded bitstream, such as from the encoded block data for the current block, an index value indicating the set of previously used elastic intra block prediction model parameters for the current block, and obtains the previously used elastic intra block prediction model parameters for the current block in accordance with the index value.

[0157] In some implementations, the decoder omits, skips, avoids, or excludes obtaining the elastic intra block prediction model parameters, or corresponding encoded, such as entropy coded, elastic intra block prediction model parameters, from the encoded bitstream, the decoder accesses, such as decodes or otherwise obtains, differential elastic intra block prediction model reference parameters, or corresponding encoded, such as entropy coded, differential elastic intra block prediction model reference parameters, from the encoded bitstream, such as from the encoded block data for the current block, the decoder uses the elastic intra block prediction model parameters obtained using the matched reference templates as elastic intra block prediction model reference parameters, and the decoder obtains, as the elastic intra block prediction model parameters for the current block, a result of combining, such as by adding, the elastic intra block prediction model reference parameters, obtained using the matched reference templates, and the differential elastic intra block prediction model reference parameters, obtained from the encoded bitstream.

[0158] In some implementations, the decoder may access information describing the matched reference templates from the encoded bitstream, such as from the encoded block data for the current block, which may include information describing a size, such as horizontal size, vertical size, or both, of the matched reference templates, information indicating the orientation or relative location of the matched reference templates, or both.

[0159] The decoder obtains, determines, or calculates a prediction block (at 1060) of predicted pixel values for the current block using the elastic intra block prediction model with the elastic intra block prediction model parameters (obtained at 1050) and the reference block (obtained at 1030). Obtaining the prediction block (at 1060) includes obtaining a predicted value of a current pixel for the current block using the elastic intra block prediction model,the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from the previously decoded reference block. Obtaining the prediction block (at 1060) is similar to obtaining the prediction block as shown (at 860) in FIG. 8, except as is described herein or as is otherwise clear from context.

[0160] The decoder obtains, determines, or calculates decoded data (at 1070) for the current block. In some implementations, the decoder accesses, such as decodes or otherwise obtains, residual, or prediction error, data, such as entropy coded residual data, from the encoded bitstream, such as from the encoded block data for the current block, and obtains, as the decoded block data for the current block, a result of combining, such as by adding, the decoded residual block data and the prediction data for the current block, such as on a per- pixel basis.

[0161] The decoder includes the decoded block data for the current block in decoded data for the current frame and obtains reconstructed frame data for the current frame using the decoded data for the current frame. The decoder includes the reconstructed frame data in reconstructed video data.

[0162] The decoder outputs the reconstructed video data (at 1080).

[0163] 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.

[0164] 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.

[0165] 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 aspects or 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 “animplementation” 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.

[0166] 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 from implementations of methods in accordance with the disclosed subject matter.

[0167] The implementations of the transmitting computing and communication device 100A 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.

[0168] Further, in one implementation, for example, the transmitting computing and communication device 100A 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.

[0169] The transmitting computing and communication device 100A 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 communicationdevice 100A 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 100A 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 100A 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.

[0170] 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.

[0171] 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) or intangible 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.

[0172] 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

CLAIMS What is claimed is:

1. A method comprising: generating reconstructed video data by decoding an encoded bitstream, wherein decoding the encoded bitstream includes: accessing, from the encoded bitstream, encoded block data for a current block of a current frame; accessing, from the encoded bitstream, data indicating use of elastic intra block prediction mode for decoding the current block; obtaining, for decoding the current block using an elastic intra block prediction model, elastic intra block prediction model parameters; obtaining a predicted value of a current pixel from the current block using the elastic intra block prediction model, the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from a previously decoded reference block in the current frame that differs from one or more previously decoded blocks adjacent to the current block; obtaining decoded block data for the current block using the predicted value; obtaining reconstructed frame data for the current frame using the decoded block data; and including the reconstructed frame data in the reconstructed video data; and outputting the reconstructed video data.

2. The method of claim 1, wherein: obtaining the elastic intra block prediction model parameters includes decoding the elastic intra block prediction model parameters from the encoded bitstream.

3. The method of claim 1, wherein obtaining the elastic intra block prediction model parameters includes: decoding differential elastic intra block prediction model parameters from the encoded bitstream; and obtaining the elastic intra block prediction model parameters by adding the differential elastic intra block prediction model parameters to previously used elastic intrablock prediction model parameters previously used for decoding another block in the current frame.

4. The method of claim 1, wherein obtaining the elastic intra block prediction model parameters includes: obtaining first template pixels from one or more previously decoded blocks adjacent to the current block; and obtaining second template pixels from one or more previously decoded blocks adjacent to a previously decoded reference block in the current frame that differs from the one or more previously decoded blocks adjacent to the current block.

5. The method of claim 4, wherein obtaining the elastic intra block prediction model parameters includes: decoding differential elastic intra block prediction model reference parameters from the encoded bitstream; obtaining elastic intra block prediction model reference parameters using the first template pixels and the second template pixels; and obtaining the elastic intra block prediction model parameters by adding the differential elastic intra block prediction model reference parameters to the elastic intra block prediction model reference parameters.

6. The method of claim 4, wherein obtaining the elastic intra block prediction model parameters includes: obtaining the elastic intra block prediction model parameters using the first template pixels and the second template pixels.

7. The method of claim 4, wherein obtaining the elastic intra block prediction model parameters includes: obtaining preliminary elastic intra block prediction model parameters by performing parameter fitting using the first template pixels and the second template pixels; and obtaining the elastic intra block prediction model parameters by quantizing the preliminary elastic intra block prediction model parameters.

8. The method of claim 6, wherein:the elastic intra block prediction model is a linear model; and the parameter fitting includes linear regression.

9. The method of claim 4, wherein: the first template pixels include: previously decoded pixels from a first defined cardinality of rows immediately adjacent to the current block; and previously decoded pixels from a second defined cardinality of columns immediately adjacent to the current block; and the second template pixels include: previously decoded pixels from the first defined cardinality of rows immediately adjacent to the previously decoded reference block; and previously decoded pixels from the second defined cardinality of columns immediately adjacent to the previously decoded reference block.

10. The method of claim 1, wherein: the elastic intra block prediction model is a linear model; the elastic intra block prediction model parameters include a first parameter and a second parameter; and obtaining the predicted value includes obtaining, as the predicted value, a sum of the second parameter and a result of multiplying the first parameter by the value of the corresponding reference pixel.

11. The method of claim 1, wherein: the elastic intra block prediction model is a non-linear model; the elastic intra block prediction model parameters include a first parameter, a second parameter, a third parameter, a fourth parameter, a fifth parameter, a sixth parameter, and a seventh parameter; and obtaining the predicted value includes obtaining, as the predicted value, a sum of: a result of multiplying the first parameter by the value of the corresponding reference pixel; a result of multiplying the second parameter by a value of a pixel immediately left of the corresponding reference pixel;a result of multiplying the third parameter by a value of a pixel immediately right of the corresponding reference pixel; a result of multiplying the fourth parameter by a value of a pixel immediately above the corresponding reference pixel; a result of multiplying the fifth parameter by a value of a pixel immediately below the corresponding reference pixel; a result of multiplying the value of the corresponding reference pixel by a result of multiplying the sixth parameter by the value of the corresponding reference pixel; and the seventh parameter.

12. A method comprising: generating an encoded bitstream by encoding input video data, wherein encoding the input video data includes: obtaining a current frame from the input video data; obtaining a current block from the current frame; obtaining, for encoding the current block using an elastic intra block prediction model, elastic intra block prediction model parameters; obtaining a predicted value of a current pixel from the current block using the elastic intra block prediction model, the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from a previously decoded reference block in the current frame that differs from one or more previously decoded blocks adjacent to the current block; obtaining encoded block data for the current block using the predicted value; including, in the encoded bitstream, the encoded block data; and including, in the encoded bitstream, data indicating the use of elastic intra block prediction mode for the current block; and outputting the encoded bitstream.

13. The method of claim 12, wherein obtaining the encoded block data includes: obtaining, as differential elastic intra block prediction model parameters, a result of subtracting previously used elastic intra block prediction model parameters previously used for decoding another block in the current frame from the elastic intra block prediction model parameters; andincluding the differential elastic intra block prediction model parameters in the encoded bitstream.

14. The method of claim 12, wherein obtaining the elastic intra block prediction model parameters includes: obtaining first template pixels from one or more previously decoded blocks adjacent to the current block; and obtaining second template pixels from one or more previously decoded blocks adjacent to a previously decoded reference block in the current frame that differs from the one or more previously decoded blocks adjacent to the current block.

15. The method of claim 14, wherein obtaining the elastic intra block prediction model parameters includes: obtaining elastic intra block prediction model reference parameters by parameter fitting using the first template pixels and the second template pixels; obtaining the elastic intra block prediction model parameters by parameter fitting using the current block and the reference block; obtaining differential elastic intra block prediction model reference parameters by subtracting the elastic intra block prediction model reference parameters from the elastic intra block prediction model parameters; and including the differential elastic intra block prediction model reference parameters in the encoded bitstream.

16. The method of claim 14, wherein obtaining the elastic intra block prediction model parameters includes: obtaining preliminary elastic intra block prediction model parameters by performing parameter fitting using the first template pixels and the second template pixels; and obtaining the elastic intra block prediction model parameters by quantizing the preliminary elastic intra block prediction model parameters.

17. The method of claim 14, wherein: the first template pixels include: previously decoded pixels from a first defined cardinality of rows immediately adjacent to the current block; andpreviously decoded pixels from a second defined cardinality of columns immediately adjacent to the current block; and the second template pixels include: previously decoded pixels from the first defined cardinality of rows immediately adjacent to the previously decoded reference block; and previously decoded pixels from the second defined cardinality of columns immediately adjacent to the previously decoded reference block.

18. The method of claim 14, wherein: the elastic intra block prediction model is a linear model; the elastic intra block prediction model parameters include a first parameter and a second parameter; and obtaining the predicted value includes obtaining, as the predicted value, a sum of the second parameter and a result of multiplying the first parameter by the value of the corresponding reference pixel.

19. The method of claim 14, wherein: the elastic intra block prediction model is a non-linear model; the elastic intra block prediction model parameters include a first parameter, a second parameter, a third parameter, a fourth parameter, a fifth parameter, a sixth parameter, and a seventh parameter; and obtaining the predicted value includes obtaining, as the predicted value, a sum of: a result of multiplying the first parameter by the value of the corresponding reference pixel; a result of multiplying the second parameter by a value of a pixel immediately left of the corresponding reference pixel; a result of multiplying the third parameter by a value of a pixel immediately right of the corresponding reference pixel; a result of multiplying the fourth parameter by a value of a pixel immediately above the corresponding reference pixel; a result of multiplying the fifth parameter by a value of a pixel immediately below the corresponding reference pixel;a result of multiplying the value of the corresponding reference pixel by a result of multiplying the sixth parameter by the value of the corresponding reference pixel; and the seventh parameter.

20. 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: generate reconstructed video data, wherein, to generate the reconstructed video data, the processor is configured to execute the instructions to decode an encoded bitstream, wherein, to decode the encoded bitstream, the processor is configured to execute the instructions to: access, from the encoded bitstream, encoded block data for a current block of a current frame; access, from the encoded bitstream, data indicating use of elastic intra block prediction mode for decoding the current block; obtain, for decoding the current block using an elastic intra block prediction model, elastic intra block prediction model parameters; obtain a predicted value of a current pixel from the current block using the elastic intra block prediction model, the elastic intra block prediction model parameters, and a value of a corresponding reference pixel from a previously decoded reference block in the current frame that differs from one or more previously decoded blocks adjacent to the current block; obtain decoded block data for the current block using the predicted value; obtain reconstructed frame data for the current frame using the decoded block data; and include the reconstructed frame data in the reconstructed video data; and output the reconstructed video data.

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