Signal transmission of global motion vector in picture header

Abstract

To provide signal transmission of a global motion vector in a suitable picture header.SOLUTION: A decoder includes a circuit network. The circuit network is configured to receive a bitstream, extract a header including a list of reference frames that can be made available for global motion compensation, use the header to determine a global motion model for the current block where the global motion is for a reference frame contained in the list of reference frames, and decode the current block using the global motion model. Related devices, systems, techniques, and articles are also described.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 838,517, filed April 25, 2019, and entitled “SIGNALING OF GLOBAL MOTION VECTOR IN PICTURE HEADER,” which is incorporated by reference in its entirety.

[0002] The present invention relates generally to the field of video compression. In particular, the present invention is directed to signaling global motion vectors relative to available reference frames. [Background technology]

[0003] A video codec may include electronic circuitry or software that compresses or decompresses digital video. It can convert uncompressed video into a compressed format, or vice versa. In the context of video compression, a device that compresses video (and / or performs some function thereof) may typically be called an encoder, and a device that decompresses video (and / or performs some function thereof) may be called a decoder.

[0004] The format of the compressed data can conform to standard video compression specifications. The compression can be lossy, in that the compressed video lacks certain information present in the original video. Consequences of this can include that the decompressed video may have lower quality than the original uncompressed video, because there is insufficient information to accurately reconstruct the original video.

[0005] There may be a complex relationship between video quality, the amount of data used to represent the video (e.g., as determined by bit rate), the complexity of the encoding and decoding algorithms, sensitivity to data loss and errors, ease of organization, random access, end-to-end delay (e.g., latency), and the like.

[0006] Motion compensation can include an approach for predicting a video frame or a portion thereof given a reference frame, such as a past and / or future frame, by considering the motion of the camera and / or objects in the video. This can be employed in encoding and decoding video data for video compression, for example, in encoding and decoding using the Motion Picture Experts Group (MPEG)-2 (also referred to as Advanced Video Coding (AVC) and H.264) standard. Motion compensation can describe a picture in terms of a transformation of a reference picture to a current picture. The reference picture can be from the past in time compared to the current picture and from the future compared to the current picture. Compression efficiency can be improved when images can be accurately synthesized from previously transmitted and / or stored images. Summary of the Invention [Means for solving the problem]

[0007] In one aspect, the decoder includes circuitry configured to receive a bitstream, extract a header including a list of reference frames available for global motion compensation, use the header to determine a global motion model for a current block whose global motion is relative to a reference frame contained in the list of reference frames, and decode the current block using the global motion model.

[0008] In another aspect, a method includes receiving, by a decoder, a bitstream. The method includes extracting a header including a list of reference frames available for global motion compensation. The method includes determining, using the header, a global motion model for a current block, whose global motion is relative to a reference frame contained in the list of reference frames. The method includes decoding the current block using the global motion model.

[0009] The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. The present specification also provides, for example, the following items: (Item 1) 1. A decoder, comprising: A circuitry comprising: receiving a bitstream; extracting a header containing a list of reference frames available for global motion compensation; determining a global motion model for the current block using the header, the global motion being relative to a reference frame contained in the list of reference frames; decoding the current block using the global motion model; and A circuit network configured to: A decoder comprising: (Item 2) 2. The decoder of claim 1, wherein the reference frames are indexed in the list by order relative to a current frame. (Item 3) 2. The decoder of item 1, wherein all available frames are included in the list. (Item 4) 2. The decoder of claim 1, wherein the header includes a picture parameter set or a sequence parameter set. (Item 5) 2. The decoder of claim 1, wherein the header includes a flag that characterizes whether global motion is present for the current block. (Item 6) 2. The decoder of claim 1, wherein the header contains parameters of the global motion models contained in the list. (Item 7) 2. The decoder of claim 1, wherein the header includes a field that characterizes the presence of global motion for frames in the list. (Item 8) 2. The decoder of claim 1, wherein the header includes an index into the list. (Item 9) an entropy decoder processor configured to receive the bitstream and decode the bitstream into quantized coefficients; an inverse quantization and inverse transform processor, the inverse quantization and inverse transform processor configured to process the quantized coefficients including performing an inverse discrete cosine; A deblocking filter; A frame buffer; Intra prediction processor Item 1. The decoder of item 1, further comprising: (Item 10) 2. The decoder of claim 1, wherein the current block is a coding tree unit. (Item 11) 2. The decoder of claim 1, wherein the current block is a coding unit. (Item 12) 2. The decoder of claim 1, wherein the current block is a prediction unit. (Item 13) 1. A method, comprising: receiving, by a decoder, a bitstream; extracting a header containing a list of reference frames available for global motion compensation; determining a global motion model for the current block using the header, the global motion being relative to a reference frame contained in the list of reference frames; decoding the current block using the global motion model; and A method comprising: (Item 14) Item 14. The method of item 13, wherein the reference frames are indexed in the list by order relative to the current frame. (Item 15) Item 14. The method according to item 13, wherein all available frames are included in the list. (Item 16) Item 14. The method according to item 13, wherein the header includes a picture parameter set (PPS) or a sequence parameter set (SPS). (Item 17) Item 14. The method of item 13, wherein the header includes a flag that characterizes whether global motion is present for the current block. (Item 18) Item 14. The method according to item 13, wherein the header includes parameters of the global motion models contained in the list. (Item 19) Item 14. The method of item 13, wherein the header includes a field that characterizes the presence of global motion for the frames in the list. (Item 20) Item 14. The method of item 13, wherein the header includes an index into the list. (Item 21) The decoder further comprises: an entropy decoder processor configured to receive the bitstream and decode the bitstream into quantized coefficients; an inverse quantization and inverse transform processor, the inverse quantization and inverse transform processor configured to process the quantized coefficients including performing an inverse discrete cosine; A deblocking filter; A frame buffer; Intra prediction processor Item 14. The method of item 13, comprising: (Item 22) Item 14. The method of item 13, wherein the current block is a coding tree unit. (Item 23) Item 14. The method of item 13, wherein the current block is a coding unit. (Item 24) Item 14. The method of item 13, wherein the current block is a prediction unit. [Brief description of the drawings]

[0010] For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of the invention, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown in the drawings.

[0011] [Figure 1] FIG. 1 is a diagram illustrating motion vectors of an example frame with global and local motion.

[0012] [Diagram 2] FIG. 2 is a process flow diagram according to some example implementations of the present subject matter.

[0013] [Diagram 3] FIG. 3 is a system block diagram of an example decoder in accordance with some example implementations of the present subject matter.

[0014] [Figure 4] FIG. 4 is a process flow diagram according to some example implementations of the present subject matter.

[0015] [Diagram 5] FIG. 5 is a system block diagram of an example encoder in accordance with some example implementations of the present subject matter.

[0016] [Figure 6] FIG. 6 is a block diagram of a computing system that may be used to implement any one or more of, or any one or more portions of, the methodologies disclosed herein.

[0017] The drawings are not necessarily to scale and may be illustrated by phantom lines, schematic representations, and partial views. In some instances, details that are not necessary for an understanding of the embodiments or that make other details difficult to perceive may be omitted. Like reference symbols in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Global motion in video refers to motion that occurs in the entire frame. Global motion may be caused by camera motion, e.g., camera panning and zooming may generate motion in a frame that may typically affect the entire frame. Motion that is present within a portion of a video may be referred to as local motion. Local motion may be caused by moving objects in a scene, such as, but not limited to, an object moving from left to right in a scene. Video may contain a combination of local and global motion. Some implementations of the present subject matter may provide an efficient approach for communicating global motion to a decoder and the use of global motion vectors in improving compression efficiency.

[0019] FIG. 1 is a diagram illustrating motion vectors of an example frame 100 with global and local motion. Frame 100 may include several blocks of pixels, illustrated as squares, and their associated motion vectors, illustrated as arrows. Squares (e.g., blocks of pixels) with arrows pointing up and to the left indicate blocks with motion that may be considered to be global motion, and squares with arrows pointing in the other direction (indicated by 104) indicate blocks with local motion. In the illustrated example of FIG. 1, many of the blocks have the same global motion. Signaling the global motion in a header, such as a picture parameter set (PPS) or sequence parameter set (SPS), and using the signaled global motion may reduce the motion vector information required by blocks and may result in improved prediction. For illustrative purposes, the embodiments described below refer to determining and / or applying global or local motion vectors at the block level, although global motion vectors may be determined and / or applied with respect to any region of a frame and / or picture (including, but not limited to, a region comprised of multiple blocks, a region bounded by any geometric form, such as, but not limited to, a region defined by geometric and / or exponential coding, in which one or more lines and / or curves bounding a shape may be angled and / or curved, and / or the entire frame and / or picture). Although signaling is described herein as being performed at the frame level and / or within the header and / or frame parameter set, signaling may alternatively or additionally be performed at a sub-picture level, where a sub-picture may include any region of a frame and / or picture as described above.

[0020] As an example, still referring to FIG. 1, a simple translational motion is expressed as a two-component MV x , M.V. yMore complex motions such as rotation, magnification, and warping may be described using affine motion vectors, where an "affine motion vector" as used in this disclosure is a vector that describes the uniform displacement of a set of pixels or points, such as a video picture and / or a set of pixels that illustrate an object represented within a picture that moves across a field of view in a video without changing its apparent shape during the motion. Some approaches to video encoding and / or decoding may use a four-parameter or six-parameter affine model for motion compensation in inter-picture coding. For example, a six-parameter affine motion can be described as follows: x'=ax+by+c y'=dx+ey+f The four-parameter affine motion can be described as follows. x'=ax+by+c y'=-bx+ay+f

[0021] where (x,y) and (x',y') are pixel locations in the current and reference pictures, respectively, and a, b, c, d, e, and f are parameters of the affine motion model.

[0022] Still referring to FIG. 1, parameters used to describe affine motion may be signaled to a decoder to apply affine motion compensation at the decoder. In some approaches, the motion parameters may be signaled explicitly or by signaling translational control point motion vectors (CPMVs) and then deriving affine motion parameters from the translational motion vectors. Two control point motion vectors (CPMVs) may be utilized to derive affine motion parameters for a four-parameter affine motion model, and three control point translational motion vectors (CPMVs) may be utilized to obtain parameters for a six-parameter motion model. Signaling affine motion parameters using control point motion vectors may enable the use of efficient motion vector coding methods to signal affine motion parameters.

[0023] Continuing with reference to FIG. 1, some modern video compression techniques may use multiple reference frames in inter prediction. When multiple reference frames exist, global motion relative to the available reference frames may be signaled to more efficiently apply motion compensation and improve compression efficiency. A list of frames available for reference may be maintained in a frame list List0. The frames in the list may be indexed by their order relative to the current frame. All frames available for use as references in coding the current picture may be indexed in List0. Global motion parameters may be defined for all available reference frames. The presence or absence of global motion for frames in the reference list may also be signaled, which may enable efficient signaling of global motion information.

[0024] For example, still referring to FIG. 1, Table 1 shows a new PPS with global motion parameters for one or more frames in the reference picture list. In the example of Table 1, up to 16 reference pictures may be signaled. The presence of global motion for each available reference frame may be signaled. For all frames where global motion exists, the global motion parameters may be encoded as shown in Table 1. If a predicted block in the current picture does not use global motion from a previously coded frame that is available for reference, the corresponding global motion parameters may not be coded. On the encoder side, if the PPS needs to be updated after encoding the current picture, this may incur a frame delay. Alternatively, an efficient method of encoding may be able to predict which available reference frames are not suitable for global motion compensation and remove such frames from the PPS. [Table 1-1] [Table 1-2]

[0025] In an embodiment, still referring to FIG. 1, sps_affine_enabled_flag in the PPS and / or SPS may specify whether affine model-based motion compensation may be used for inter prediction. If sps_affine_enabled_flag is equal to 0, the syntax may be constrained such that affine model-based motion compensation is not used in a coded video sequence (CLVS), and inter_affine_flag and cu_affine_type_flag may not be present in the coding unit syntax of the CLVS. Otherwise (sps_affine_enabled_flag is equal to 1), affine model-based motion compensation may be used in the CLVS.

[0026] Continuing with reference to FIG. 1 , sps_affine_type_flag in the PPS and / or SPS may specify whether 6-parameter affine model-based motion compensation may be used for inter prediction. If sps_affine_type_flag is equal to 0, the syntax may be constrained such that 6-parameter affine model-based motion compensation is not used in CLVS, and cu_affine_type_flag may not be present in the coding unit syntax of CLVS. Otherwise (sps_affine_type_flag is equal to 1), 6-parameter affine model-based motion compensation may be used in CLVS. When not present, the value of sps_affine_type_flag may be inferred to be equal to 0.

[0027] Thus, still referring to FIG. 1, some implementations of the present subject matter may include utilizing global motion between a current frame and one of several reference frames. The reference frame to utilize may be explicitly signaled (e.g., within the PPS). In some implementations, if the reference frame to be utilized is not explicitly signaled, the reference frame to be utilized may be the frame immediately preceding the current frame. Such an approach may enable more accurate motion representation (e.g., smaller motion vector residuals) and smaller pixel residuals.

[0028] FIG. 2 is a process flow diagram illustrating an example process 200 that utilizes global motion between a current frame and one of several reference frames.

[0029] At step 205, still referring to FIG. 2, a bitstream is received by the decoder. A current block may be contained within the bitstream that the decoder receives. The bitstream may include data found in a stream of bits that is input to the decoder, for example, when using data compression. The bitstream may include information necessary to decode the video. The receiving step may include extracting and / or parsing the block and associated signaling information from the bitstream. In some implementations, the current block may include a coding tree unit (CTU), a coding unit (CU), or a prediction unit (PU).

[0030] 2, in step 210, a header may be extracted. The header may include a list of reference frames available for global motion compensation. In step 215, a global motion model for the current block may be determined using the header. The global motion may be relative to a reference frame contained in the list of reference frames. In step 220, the current block may be decoded using the global motion model.

[0031] 3 is a system block diagram illustrating an example decoder 300 capable of decoding a bitstream 328 utilizing global motion between a current frame and one of several reference frames. The decoder 300 may include an entropy decoder processor 304, an inverse quantization and inverse transform processor 308, a deblocking filter 312, a frame buffer 316, a motion compensation processor 320, and an intra prediction processor 324.

[0032] In operation, and still referring to FIG. 3, a bitstream 328 may be received by the decoder 300 and input to the entropy decoder processor 304, which may entropy decode a portion of the bitstream into quantized coefficients. The quantized coefficients may be provided to the inverse quantization and inverse transform processor 308, which may perform inverse quantization and inverse transform and generate a residual signal, which may be added to the output of the motion compensation processor 320 or the intra prediction processor 324, depending on the processing mode. The output of the motion compensation processor 320 and the intra prediction processor 324 may include block predictions based on previously decoded blocks. The sum of the predictions and residuals may be processed by the deblocking filter 630 and stored in the frame buffer 640.

[0033] FIG. 4 is a process flow diagram illustrating an example embodiment of a process 400 for encoding video using INSERT according to some aspects of what is disclosed herein, which may improve compression efficiency while reducing the complexity of the encoding step. In step 405, a video frame may undergo initial block segmentation, which may be accomplished using a tree-structured macroblock partitioning scheme, which may include, for example, partitioning a picture frame into CTUs and CUs. In step 410, a global motion for the current frame may be determined, including determining a reference frame from a number of available reference frames. In step 415, the global motion information and the block may be encoded and included in the bitstream. The encoded information may include an index to a list of available reference frames. The encoding may include, for example, utilizing inter-prediction and intra-prediction modes.

[0034] FIG. 5 is a system block diagram illustrating a non-limiting example of a video encoder 500 that can utilize global motion between a current frame and one of several reference frames. The exemplary video encoder 500 may receive an input video 504, which may first be segmented or divided according to a processing scheme such as a tree-structured macroblock partitioning scheme (e.g., quadtree+binary tree). An example of a tree-structured macroblock partitioning scheme may include partitioning a picture frame into large block elements called coding tree units (CTUs). In some implementations, each CTU may be further partitioned one or more times into several sub-blocks, called coding units (CUs). The end result of this partitioning may include a group of sub-blocks, which may be called prediction units (PUs). Transform units (TUs) may also be utilized.

[0035] 5, the exemplary video encoder 500 may include an intra-prediction processor 415, a motion estimation / compensation processor 512 (also referred to as an inter-prediction processor) capable of supporting global motion between a current frame and one of several reference frames, a transform / quantization processor 516, an inverse quantization / inverse transform processor 520, an in-loop filter 524, a decoded picture buffer 528, and / or an entropy coding processor 532. Bitstream parameters may be input to the entropy coding processor 532 for inclusion in an output bitstream 536.

[0036] In operation, and continuing to refer to FIG. 5, for each block of a frame of the input video 504, it may be determined whether to process the block via intra-picture prediction or using motion estimation / compensation. The block may be provided to an intra-prediction processor 508 or a motion estimation / compensation processor 512. If the block is to be processed via intra-prediction, the intra-prediction processor 508 may perform processing and output a predictor. If the block is to be processed via motion estimation / compensation, the motion estimation / compensation processor 512 may perform processing that includes using global motion between the current frame and one of several reference frames, if applicable.

[0037] With further reference to FIG. 5, a residual may be formed by subtracting the predictor from the input video. The residual may be received by a transform / quantization processor 516, which may perform a transform process (e.g., a discrete cosine transform (DCT)) to produce coefficients, which may be quantized. The quantized coefficients and any associated signaling information may be provided to an entropy coding processor 532 for entropy encoding and inclusion in an output bitstream 536. The entropy encoding processor 532 may assist in encoding signaling information related to encoding the current block. In addition, the quantized coefficients may be combined with the predictor and provided to an inverse quantization / inverse transform processor 520, which may reconstruct pixels that may be processed by an in-loop filter 524, the output of which may be stored in a decoded picture buffer 528 for use by a motion estimation / compensation processor 512, which may exploit global motion between the current frame and one of several reference frames.

[0038] Still referring to Figure 5, several variations have been described in detail above, but other modifications or additions are also possible. For example, in some implementations, the current block may include any symmetric block (8x8, 16x16, 32x32, 64x64, 128x128, and the like) and any asymmetric block (8x4, 16x8, and the like).

[0039] Continuing with reference to FIG. 5, in some implementations, a quad-tree plus binary decision tree (QTBT) may be implemented. In QTBT, at the coding tree unit level, partition parameters of QTBT may be dynamically derived to fit local characteristics without transmitting any overhead. Then, at the coding unit level, a joint classifier decision tree structure may eliminate unnecessary iterations and control the risk of erroneous prediction. In some implementations, an LTR frame block update mode may be available as an additional option available per leaf node of QTBT.

[0040] In some implementations, and still referring to FIG. 5, additional syntax elements may be signaled at different hierarchical levels of the bitstream. For example, a flag may be enabled throughout the sequence by including an enable flag coded in a sequence parameter set (SPS). Additionally, a CTU flag may be coded at the coding tree unit (CTU) level.

[0041] It should be noted that any one or more of the aspects and embodiments described herein may be conveniently implemented using digital electronic circuitry, integrated circuitry, specially designed application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), computer hardware, firmware, software, and / or combinations thereof, as realized and / or implemented in one or more machines (e.g., one or more computing devices utilized as user computing devices for electronic documents, one or more server devices, such as document servers, etc.) programmed according to the teachings herein, as would be apparent to one skilled in the computer arts. These various aspects or features may include implementation in one or more computer programs and / or software executable and / or interpretable on a programmable system including at least one programmable processor, which may be special purpose or general purpose, coupled to receive data and instructions from and transmit data and instructions to a storage system, at least one input device, and at least one output device. Appropriate software coding may be readily prepared by skilled programmers based on the teachings of the present disclosure, as would be apparent to one skilled in the software arts. The aspects and implementations discussed above that employ software and / or software modules may also include suitable hardware to assist in implementing the machine-executable instructions of the software and / or software modules.

[0042] Such software may be a computer program product employing a machine-readable storage medium. A machine-readable storage medium may be any medium capable of storing and / or encoding a sequence of instructions for execution by a machine (e.g., a computing device) and causing the machine to perform any one of the methodologies and / or embodiments described herein. Examples of machine-readable storage media include, but are not limited to, magnetic disks, optical disks (e.g., CDs, CD-Rs, DVDs, DVD-Rs, etc.), magneto-optical disks, read-only memory "ROM" devices, random access memory "RAM" devices, magnetic cards, optical cards, solid-state memory devices, EPROMs, EEPROMs, programmable logic devices (PLDs), and / or any combination thereof. Machine-readable media, as used herein, is intended to include a single medium as well as a collection of physically separate media, such as, for example, a collection of compact discs or one or more hard disk drives in combination with a computer memory. As used herein, machine-readable storage media does not include a transitory form of signal transmission.

[0043] Such software may also include information (e.g., data) carried as a data signal on a data carrier, such as a carrier wave. For example, machine-executable information may be included as a data carrying signal embodied in a data carrier, which signal encodes a sequence of instructions, or a portion thereof, for execution by a machine (e.g., a computing device), and any associated information (e.g., data structures and data) that causes the machine to perform any one of the methodologies and / or embodiments described herein.

[0044] Examples of computing devices include, but are not limited to, e-book reading devices, computer workstations, terminal computers, server computers, handheld devices (e.g., tablet computers, smart phones, etc.), web appliances, network routers, network switches, network bridges, any machine capable of executing a sequence of instructions that define actions to be taken by the machine, and any combination thereof. In one embodiment, the computing device may include and / or be included within a kiosk.

[0045] 6 illustrates a diagrammatic representation of one embodiment of a computing device in the exemplary form of a computer system 600 on which a set of instructions for causing a control system to perform any one or more of the aspects and / or methodologies of the present disclosure may be executed. It is also envisioned that multiple computing devices may be utilized to implement a specially configured set of instructions for causing one or more of the devices to perform any one or more of the aspects and / or methodologies of the present disclosure. The computer system 600 includes a processor 604 and a memory 608 that communicate with each other and with other components via a bus 612. The bus 612 may include any of several types of bus structures, including, but not limited to, a memory bus, a memory controller, a peripheral bus, a local bus, and any combination thereof, using any of a variety of bus architectures.

[0046] Memory 608 may include a variety of components (e.g., machine-readable media), including, but not limited to, random access memory components, read-only components, and any combination thereof. In one embodiment, a basic input / output system 616 (BIOS), including the basic routines that help to transfer information between elements within computer system 600, such as during start-up, may be stored in memory 608. Memory 608 may also include (e.g., stored on one or more machine-readable media) instructions (e.g., software) 620 that embody any one or more of the aspects and / or methodologies of the present disclosure. In another embodiment, memory 608 may further include any number of program modules, including, but not limited to, an operating system, one or more application programs, other program modules, program data, and any combination thereof.

[0047] Computer system 600 may also include a storage device 624. Examples of storage devices (e.g., storage device 624) include, but are not limited to, hard disk drives, magnetic disk drives, optical disk drives in combination with optical media, solid-state memory devices, and any combination thereof. Storage device 624 may be connected to bus 612 by an appropriate interface (not shown). Exemplary interfaces include, but are not limited to, SCSI, Advanced Technology Attachment (ATA), Serial ATA, Universal Serial Bus (USB), IEEE 1394 (FIREWIRE®), and any combination thereof. In one embodiment, storage device 624 (or one or more components thereof) may be removably interfaced with computer system 600 (e.g., via an external port connector (not shown)). In particular, storage device 624 and associated machine-readable media 628 may provide non-volatile and / or volatile storage of machine-readable instructions, data structures, program modules, and / or other data for computer system 600. In one embodiment, software 620 may reside, completely or partially, within machine-readable medium 628. In another embodiment, software 620 may reside, completely or partially, within processor 604.

[0048] Computer system 600 may also include input devices 632. In one embodiment, a user of computer system 600 may type commands and / or other information into computer system 600 via input devices 632. Examples of input devices 632 include, but are not limited to, alphanumeric input devices (e.g., keyboards), pointing devices, joysticks, gamepads, audio input devices (e.g., microphones, voice response systems, etc.), cursor control devices (e.g., mice), touchpads, optical scanners, video capture devices (e.g., still cameras, video cameras), touch screens, and any combination thereof. Input devices 632 may be interfaced to bus 612 via any of a variety of interfaces (not shown), including, but not limited to, a serial interface, a parallel interface, a game port, a USB interface, a FIREWIRE® interface, an interface directly to bus 612, and any combination thereof. Input devices 632 may include a touch screen interface, which may be part of or separate from display 636, discussed further below. The input device 632 may be utilized as a user selection device for selecting one or more graphical representations within a graphical interface such as those described above.

[0049] A user may also input commands and / or other information to computer system 600 via storage device 624 (e.g., a removable disk drive, flash drive, etc.) and / or network interface device 640. A network interface device, such as network interface device 640, may be utilized to connect computer system 600 to one or more of a variety of networks, such as network 644, and one or more remote devices 648 connected thereto. Examples of network interface devices include, but are not limited to, a network interface card (e.g., a mobile network interface card, a LAN card), a modem, and any combination thereof. Examples of networks include, but are not limited to, a wide area network (e.g., the Internet, a corporate network), a local area network (e.g., a network associated with an office, a building, a campus, or other relatively small geographic space), a telephone network, a data network associated with a telephone / voice provider (e.g., a data and / or voice network of a mobile communications provider), a direct connection between two computing devices, and any combination thereof. A network, such as network 644, may employ wired and / or wireless modes of communication. In general, any network topology may be used. Information (eg, data, software 620 , etc.) may be communicated to and / or from computer system 600 via network interface device 640 .

[0050] Computer system 600 may further include a video display adapter 652 for communicating images displayable on a display device, such as display device 636. Examples of display devices include, but are not limited to, a liquid crystal display (LCD), a cathode ray tube (CRT), a plasma display, a light emitting diode (LED) display, and any combination thereof. Display adapter 652 and display device 636 may be utilized in combination with processor 604 to provide graphical representations of aspects of the disclosure. In addition to a display device, computer system 600 may include one or more other peripheral output devices, including, but not limited to, audio speakers, a printer, and any combination thereof. Such peripheral output devices may be connected to bus 612 via a peripheral interface 656. Examples of peripheral interfaces include, but are not limited to, a serial port, a USB connection, a FIREWIRE® connection, a parallel connection, and any combination thereof.

[0051] The foregoing is a detailed description of exemplary embodiments of the present invention. Various modifications and additions may be made without departing from the spirit and scope of the present invention. Each feature of the various embodiments described above may be combined with features of other described embodiments as appropriate to provide a combination of features in a related new embodiment. Furthermore, while the foregoing describes several separate embodiments, what is described herein is merely illustrative of the application of the principles of the present invention. In addition, although certain methods herein may be illustrated and / or described as being performed in a specific order, the order may be highly variable among those skilled in the art to achieve the embodiments as disclosed herein. Thus, the present description is intended to be taken as an example only, and is not intended to otherwise limit the scope of the present invention.

[0052] In the above description and in the claims, phrases such as "at least one of" or "one or more of" may occur and be followed by a conjunctive enumeration of elements or features. The term "and / or" may also occur within a list of two or more elements or features. Unless otherwise implied or expressly contradicted by the context in which such a phrase is used, this is intended to mean any of the elements or features listed individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases "at least one of A and B," "one or more of A and B," and "A and / or B" are intended to mean "A alone, B alone, or A and B together," respectively. A similar interpretation is also intended with respect to lists containing more than two items. For example, the phrases "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, and / or C" are intended to mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together." Additionally, use of the term "based on" above and in the claims is intended to mean "based at least on," such that unrecited features or elements are also permissible.

[0053] The subject matter described herein may be embodied in a system, an apparatus, a method, and / or an article, depending on the desired configuration. The implementations described in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the subject matter described. Although some variations have been described in detail above, other modifications or additions are possible. In particular, further features and / or variations may be provided in addition to those described herein. For example, the implementations described above may be directed to various combinations and subcombinations of the disclosed features and / or combinations and subcombinations of some further features disclosed above. In addition, the logic flow depicted in the accompanying figures and / or described herein does not necessarily require the particular order shown or sequential order to achieve the desired results. Other implementations may be within the scope of the following claims.

Claims

1. A non-transitory computer-readable recording medium storing an encoded bitstream, the encoded bitstream being decodable by a decoder receiving the bitstream; the bitstream includes a coded current picture, the coded current picture including a plurality of coding tree units, each coding tree unit including one or more coding units and header information including a flag indicating that motion compensated prediction is enabled for the current coding unit; The decoder receiving the bitstream comprises: using the bitstream to build a list of stored previously decoded pictures for use as reference pictures for motion compensated prediction for the current coded picture; detecting, for a current coding unit in the current picture, a flag from header information in the bitstream for the current coding unit indicating that motion compensated prediction is enabled for the current coding unit, thereby indicating that each motion vector of the current coding unit is determined relative to a reference picture in the list based on motion vectors of neighboring coding units; if motion compensated prediction is enabled for the current coding unit, determining based on the header of the current coding unit whether a motion model for the current coding unit is translational motion, four-parameter affine motion, or six-parameter affine motion; determining at least a motion vector based on adjacent coding units, If the motion model of the current coding unit is translational, determining at least the motion vector further includes determining a translational motion vector from the motion vectors of adjacent coding units; and decoding the current coding unit using the translational motion vector; If the motion model of the current coding unit is four-parameter affine motion, determining the at least one motion vector further includes determining two control point motion vectors from the motion vectors of adjacent coding units; and decoding the current coding unit using the two control point motion vectors; if the motion model of the current coding unit is six-parameter affine motion, determining the at least one motion vector further includes determining three control point motion vectors from the motion vectors of adjacent coding units, and decoding the coding unit using the three control point motion vectors; A non-transitory computer-readable storage medium configured to perform the steps of:

2. The non-transitory computer-readable recording medium of claim 1, wherein the reference frames are indexed in the list by order relative to the current frame.

3. The non-transitory computer-readable recording medium of claim 1, wherein the header includes a picture parameter set or a sequence parameter set.

4. The non-transitory computer-readable recording medium of claim 1, wherein the header includes a flag characterizing whether global motion is present for the current block.

5. The non-transitory computer-readable recording medium of claim 1, wherein the global motion model includes a translational motion model.

6. The non-transitory computer-readable recording medium of claim 1, wherein the global motion model includes a four-parameter affine motion model.

7. The non-transitory computer-readable recording medium of claim 1, wherein the global motion model includes a six-parameter affine motion model.

8. The non-transitory computer-readable recording medium of claim 1, wherein the current picture includes a plurality of 128x128 coding tree units.

9. The non-transitory computer-readable recording medium of claim 8, wherein one of the coding tree units has a coding unit with a geometric partition.

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