Patent Description:
Video coding (video encoding and decoding) is used in a wide range of digital video applications, for example broadcast digital TV, video transmission over internet and mobile networks, real-time conversational applications such as video chat, video conferencing, DVD and Blu-ray discs, video content acquisition and editing systems, and camcorders of security applications.

The amount of video data needed to depict even a relatively short video can be substantial, which may result in difficulties when the data is to be streamed or otherwise communicated across a communications network with limited bandwidth capacity. Thus, video data is generally compressed before being communicated across modem day telecommunications networks. The size of a video could also be an issue when the video is stored on a storage device because memory resources may be limited. Video compression devices often use software and/or hardware at the source to code the video data prior to transmission or storage, thereby decreasing the quantity of data needed to represent digital video images. The compressed data is then received at the destination by a video decompression device that decodes the video data. With limited network resources and ever increasing demands of higher video quality, improved compression and decompression techniques that improve compression ratio with little to no sacrifice in picture quality are desirable.

Versatile Video Coding (Draft <NUM>) of <NUM>-<NUM>-<NUM>, (JVET) of ITU-T SG <NUM> WP <NUM> and <NPL> Document: JVET-L1001-v6 discloses a method of performing motion vector prediction for coding video data.

The purpose of this invention is to provide a solution to the problem of reducing memory capacity in storing information for deriving a temporal motion vector prediction while keeping the motion vector representation and precision in reasonable range.

This problem is solved according to the invention by providing a motion vector compression method according to claim <NUM>.

In a non-claimed embodiment, a step of performing at least one bit shift operation based on the exponent part or the mantissa part of the temporal motion vector to obtain a compressed motion vector may be applied.

In another a non-claimed embodiment, the exponent part may correspond to the most significant bit(s) (MSB) of the binary representation and the mantissa part may correspond to the least significant bit(s) (LSB) of the binary representation; or, the exponent part may correspond to LSB of the binary representation and the mantissa part may correspond to MSB of the binary representation.

Additionally, when the exponent part corresponds to MSB of the binary representation and the mantissa part corresponds to LSB of the binary representation, a value of the compressed motion vector may be derived by the following steps: deriving a first shift value by applying a right shift of M bit to the binary representation; deriving last M bit of the binary representation as a first basic binary representation; and deriving the value of the compressed motion vector by applying a left shift of the first shift value bit to the first basic binary representation.

Alternatively, when the exponent part corresponds to LSB of the binary representation and the mantissa part corresponds to MSB of the binary representation, the value of the motion vector component may be derived by the following steps: deriving last N bit of the binary representation as a second shift value; deriving a second basic binary representation by applying a right shift of N bit to the binary representation; and deriving the value of the compressed motion vector by applying a left shift of the second shift value bit to the second basic binary representation.

According to an embodiment, the temporal motion vector may comprise a motion vector horizontal component and a motion vector vertical component.

According to another embodiment, the motion vector compression method may comprise: coding a first indicator, wherein the first indicator is used to indicate whether the temporal motion vector is compressed according to the motion vector compression method according to the invention.

According to a non-claimed example, the motion vector compression method may comprise determining a value of N. Further, determining the value of N may comprises: coding the value of N; or setting a predetermined value as the value of N; or deriving the value of N based on a resolution of a picture unit, wherein the picture unit comprises a picture or a tile set; or deriving the value of N based on a size of coding tree unit (CTU) or coding unit (CU). More particularly, deriving the value of N based on the resolution of the picture unit may comprise: setting the value of N as <NUM>, when the width of the picture unit is smaller than a first threshold and the height of the picture unit is smaller than the first threshold; or, coding a second indicator to represent the value of N, when the width of the picture unit is smaller than a second threshold and the height of the picture unit is smaller than the second threshold; or, coding a third indicator to represent the value of N.

The second indicator may be binarized by a bit, and the third indicator may be binarized by two bits.

In an embodiment, the first indicator may be included in a sequence parameter set (SPS), a picture parameter set (PPS), a slice header, or a tile group header in a bitstream.

A non-claimed example provides a motion vector compression method, comprising: obtaining a temporal motion vector; determining an exponent part or a mantissa part of the temporal motion vector; performing at least one bit shift operation based on the exponent part or the mantissa part of the temporal motion vector to obtain a compressed motion vector, wherein the exponent part corresponds to Least Significant Bit (LSB) of the compressed motion vector and the mantissa part corresponds to Most Significant Bit (MSB) of the compressed motion vector; performing a temporal motion vector prediction (TMVP) using the compressed motion vector.

Another non-claimed example provides a coding method based on a motion vector, comprising: coding a first flag; performing a first method, when the first flag is a first value; and performing a second method, when the first flag is a second value, wherein the first value is different from the second value, wherein an original value of a first motion vector component of a current image block is binarized by M bits, wherein the first method comprises: applying a right shift of N bit to the original value, wherein (M-N) equals to a predetermined value, and wherein N and M are positive integers; setting the right shifted original value as a storage value of the first motion vector component; and coding a subsequent image block based on the storage value; and wherein the second method comprises: applying a clipping operation to the original value, wherein a clipped motion vector component represented by the clipped original value is restricted between -<NUM>M-N-<NUM> and <NUM>M-N-<NUM> - <NUM>; setting the clipped original value as the storage value of the first motion vector component; and coding a subsequent image block based on the storage value.

In a non-claimed embodiment, after setting the right shifted original value as the storage value of the motion vector according to the first method, the method may further comprise: applying a left shift of N bit to the storage value; wherein coding the subsequent image block based on the storage value comprises: coding the subsequent image block based on the left shifted storage value.

Alternatively, after setting the clipped original value as the storage value of the motion vector according to the second method, the method may further comprise: determining a restoration value of the first motion vector component based on the storage value, wherein the restoration value is binarized by M bits, wherein the last (M-N) bits of the restoration value is the same as the storage value, and wherein each of the first N bits of the restoration value equals to <NUM>, when the storage value is positive, and each of the first N bits of the restoration value equals to <NUM>, when the storage value is negative; wherein coding the subsequent image block based on the storage value comprises: coding the subsequent image block based on the restoration value.

In another non-claimed embodiment, the subsequent image block and the current block may be in different pictures, and the prediction mode of the subsequent image block may comprise temporal motion vector prediction (TMVP) and/or alternative temporal motion vector prediction (ATMVP).

In another embodiment, the first flag may be coded for each picture; or, the first flag may be coded for each tile; or, the first flag may be coded for each tile set; or, the first flag may be coded for each slice.

In still another embodiment, the first flag may be included in a sequence parameter set (SPS), a picture parameter set (PPS), a slice header, or a tile group header in a bitstream.

According to a non-claimed embodiment, the current image block may further have a second motion vector component, and the coding method may further comprise: coding a second flag; wherein: the first method may be performed for the second motion vector component, when the second flag is the first value; and the second method may be performed for the second motion vector component, when the second flag is the second value.

According to another non-claimed embodiment, before coding the first flag, the coding method may further comprise: determining if a resolution of a current picture is larger than or equal to a first preset value, and the current image block may be in the current picture.

Further, when the resolution of the current picture is smaller than the first preset value, the second method may be performed.

Moreover, when the current picture is divided into tile sets, the second method may be performed; or when a resolution of a tile set is smaller than a second preset value, the second method may be performed.

According to another non-claimed embodiment, before coding the first flag, the coding method may further comprise: determining if a size of a coding tree unit (CTU), a coding unit (CU), an image block, or a unit of a current image block satisfies a first size condition.

Further, if the size of CTU, CU, image block or unit of the current image block satisfies a second size condition, the first method may be performed; or, if the size of CTU, CU, image block, or unit of the current image block satisfies a third size condition, the second method may be performed.

A non-claimed example provides a coding method based on a motion vector, comprising: determining a size of a CTU, a CU, an image block, or a unit of a current image block; and performing at least one of a first method and a second method based on the size, or determining a resolution of a current picture; and performing at least one of the first method and the second method based on the resolution, wherein an original value of a first motion vector component of the current image block is binarized by M bits, wherein the first method comprises: applying a right shift of N bit to the original value, wherein (M-N) equals to a predetermined value, and wherein N and M are positive integers; setting the right shifted original value as a storage value of the first motion vector component; and coding a subsequent image block based on the storage value; and wherein the second method comprises: applying a clipping operation to the original value, wherein a clipped motion vector component represented by the clipped original value is restricted between -<NUM>M-N-<NUM> and <NUM>M-N-<NUM> - <NUM>; setting the clipped original value as the storage value of the first motion vector component; and coding a subsequent image block based on the storage value.

The above-mentioned problem is also solved by a non-transitory computer-readable storage medium storing programming for execution by a processing circuitry, wherein the programming, when executed by the processing circuitry, configures the processing circuitry to carry out any one of the methods described above.

The above-mentioned problem is also solved by a decoder, comprising circuitry configured to perform any one of the methods described above.

Additional features and advantages of the present invention will be described with reference to the drawings. In the description, reference is made to the accompanying figures that are meant to illustrate preferred embodiments of the invention. It is understood that such embodiments do not represent the full scope of the invention.

In the following embodiments of the application are described in more detail with reference to the attached figures and drawings, in which:.

In the following, identical reference signs refer to identical or at least functionally equivalent features if not explicitly specified otherwise.

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the application or specific aspects in which embodiments of the present application may be used. It is understood that embodiments of the application may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present application is defined by the appended claims.

Video coding typically refers to the processing of a sequence of pictures, which form the video or video sequence. Instead of the term "picture" the term "frame" or "image" may be used as synonyms in the field of video coding. Video coding (or coding in general) comprises two parts video encoding and video decoding. Video encoding is performed at the source side, typically comprising processing (e.g. by compression) the original video pictures to reduce the amount of data required for representing the video pictures (for more efficient storage and/or transmission). Video decoding is performed at the destination side and typically comprises the inverse processing compared to the encoder to reconstruct the video pictures. Embodiments referring to "coding" of video pictures (or pictures in general) shall be understood to relate to "encoding" or "decoding" of video pictures or respective video sequences. The combination of the encoding part and the decoding part is also referred to as CODEC (Coding and Decoding).

In case of lossless video coding, the original video pictures can be reconstructed, i.e. the reconstructed video pictures have the same quality as the original video pictures (assuming no transmission loss or other data loss during storage or transmission). In case of lossy video coding, further compression, e.g. by quantization, is performed, to reduce the amount of data representing the video pictures, which cannot be completely reconstructed at the decoder, i.e. the quality of the reconstructed video pictures is lower or worse compared to the quality of the original video pictures.

Several video coding standards belong to the group of "lossy hybrid video codecs" (i.e. combine spatial and temporal prediction in the sample domain and 2D transform coding for applying quantization in the transform domain). Each picture of a video sequence is typically partitioned into a set of non-overlapping blocks and the coding is typically performed on a block level. In other words, at the encoder the video is typically processed, i.e. encoded, on a block (video block) level, e.g. by using spatial (intra picture) prediction and/or temporal (inter picture) prediction to generate a prediction block, subtracting the prediction block from the current block (block currently processed/to be processed) to obtain a residual block, transforming the residual block and quantizing the residual block in the transform domain to reduce the amount of data to be transmitted (compression), whereas at the decoder the inverse processing compared to the encoder is applied to the encoded or compressed block to reconstruct the current block for representation. Furthermore, the encoder duplicates the decoder processing loop such that both will generate identical predictions (e.g. intra- and inter predictions) and/or re-constructions for processing, i.e. coding, the subsequent blocks.

In the following embodiments of a video coding system <NUM>, a video encoder <NUM> and a video decoder <NUM> are described based on <FIG>.

<FIG> is a schematic block diagram illustrating an example coding system <NUM>, e.g. a video coding system <NUM> (or short coding system <NUM>) that may utilize techniques of this present application. Video encoder <NUM> (or short encoder <NUM>) and video decoder <NUM> (or short decoder <NUM>) of video coding system <NUM> represent examples of devices that may be configured to perform techniques in accordance with various examples described in the present application.

As shown in <FIG>, the coding system <NUM> comprises a source device <NUM> configured to provide encoded picture data <NUM> e.g. to a destination device <NUM> for decoding the encoded picture data <NUM>.

The source device <NUM> comprises an encoder <NUM>, and may additionally, i.e. optionally, comprise a picture source <NUM>, a pre-processor (or pre-processing unit) <NUM>, e.g. a picture pre-processor <NUM>, and a communication interface or communication unit <NUM>.

The picture source <NUM> may comprise or be any kind of picture capturing device, for example a camera for capturing a real-world picture, and/or any kind of a picture generating device, for example a computer-graphics processor for generating a computer animated picture, or any kind of other device for obtaining and/or providing a real-world picture, a computer generated picture (e.g. a screen content, a virtual reality (VR) picture) and/or any combination thereof (e.g. an augmented reality (AR) picture). The picture source may be any kind of memory or storage storing any of the aforementioned pictures.

In distinction to the pre-processor <NUM> and the processing performed by the pre-processing unit <NUM>, the picture or picture data <NUM> may also be referred to as raw picture or raw picture data <NUM>.

Pre-processor <NUM> is configured to receive the (raw) picture data <NUM> and to perform pre-processing on the picture data <NUM> to obtain a pre-processed picture <NUM> or pre-processed picture data <NUM>. Pre-processing performed by the pre-processor <NUM> may, e.g., comprise trimming, color format conversion (e.g. from RGB to YCbCr), color correction, or de-noising. It can be understood that the pre-processing unit <NUM> may be optional component.

The video encoder <NUM> is configured to receive the pre-processed picture data <NUM> and provide encoded picture data <NUM> (further details will be described below, e.g., based on <FIG>).

Communication interface <NUM> of the source device <NUM> may be configured to receive the encoded picture data <NUM> and to transmit the encoded picture data <NUM> (or any further processed version thereof) over communication channel <NUM> to another device, e.g. the destination device <NUM> or any other device, for storage or direct reconstruction.

The destination device <NUM> comprises a decoder <NUM> (e.g. a video decoder <NUM>), and may additionally, i.e. optionally, comprise a communication interface or communication unit <NUM>, a post-processor <NUM> (or post-processing unit <NUM>) and a display device <NUM>.

The communication interface <NUM> of the destination device <NUM> is configured receive the encoded picture data <NUM> (or any further processed version thereof), e.g. directly from the source device <NUM> or from any other source, e.g. a storage device, e.g. an encoded picture data storage device, and provide the encoded picture data <NUM> to the decoder <NUM>.

The communication interface <NUM> and the communication interface <NUM> may be configured to transmit or receive the encoded picture data <NUM> or encoded data <NUM> via a direct communication link between the source device <NUM> and the destination device <NUM>, e.g. a direct wired or wireless connection, or via any kind of network, e.g. a wired or wireless network or any combination thereof, or any kind of private and public network, or any kind of combination thereof. The communication interface <NUM> may be, e.g., configured to package the encoded picture data <NUM> into an appropriate format, e.g. packets, and/or process the encoded picture data using any kind of transmission encoding or processing for transmission over a communication link or communication network.

The communication interface <NUM>, forming the counterpart of the communication interface <NUM>, may be, e.g., configured to receive the transmitted data and process the transmission data using any kind of corresponding transmission decoding or processing and/or de-packaging to obtain the encoded picture data <NUM>.

Both, communication interface <NUM> and communication interface <NUM> may be configured as unidirectional communication interfaces as indicated by the arrow for the communication channel <NUM> in <FIG> pointing from the source device <NUM> to the destination device <NUM>, or bi-directional communication interfaces, and may be configured, e.g. to send and receive messages, e.g. to set up a connection, to acknowledge and exchange any other information related to the communication link and/or data transmission, e.g. encoded picture data transmission.

The decoder <NUM> is configured to receive the encoded picture data <NUM> and provide decoded picture data <NUM> or a decoded picture <NUM> (further details will be described below, e.g., based on <FIG> or <FIG>).

The post-processor <NUM> of destination device <NUM> is configured to post-process the decoded picture data <NUM> (also called reconstructed picture data), e.g. the decoded picture <NUM>, to obtain post-processed picture data <NUM>, e.g. a post-processed picture <NUM>. The post-processing performed by the post-processing unit <NUM> may comprise, e.g. color format conversion (e.g. from YCbCr to RGB), color correction, trimming, or re-sampling, or any other processing, e.g. for preparing the decoded picture data <NUM> for display, e.g. by display device <NUM>.

The display device <NUM> of the destination device <NUM> is configured to receive the post-processed picture data <NUM> for displaying the picture, e.g. to a user or viewer. The display device <NUM> may be or comprise any kind of display for representing the reconstructed picture, e.g. an integrated or external display or monitor. The displays may, e.g. comprise liquid crystal displays (LCD), organic light emitting diodes (OLED) displays, plasma displays, projectors , micro LED displays, liquid crystal on silicon (LCoS), digital light processor (DLP) or any kind of other display. Although <FIG> depicts the source device <NUM> and the destination device <NUM> as separate devices, embodiments of devices may also comprise both or both functionalities, the source device <NUM> or corresponding functionality and the destination device <NUM> or corresponding functionality. In such embodiments the source device <NUM> or corresponding functionality and the destination device <NUM> or corresponding functionality may be implemented using the same hardware and/or software or by separate hardware and/or software or any combination thereof.

The encoder <NUM> (e.g. a video encoder <NUM>) or the decoder <NUM> (e.g. a video decoder <NUM>) or both encoder <NUM> and decoder <NUM> may be implemented via processing circuitry as shown in <FIG>, such as one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, hardware, video coding dedicated or any combinations thereof. The encoder <NUM> may be implemented via processing circuitry <NUM> to embody the various modules as discussed with respect to encoder 20of <FIG> and/or any other encoder system or subsystem described herein. The decoder <NUM> may be implemented via processing circuitry <NUM> to embody the various modules as discussed with respect to decoder <NUM> of <FIG> and/or any other decoder system or subsystem described herein. The processing circuitry may be configured to perform the various operations as discussed later. As shown in <FIG>, if the techniques are implemented partially in software, a device may store instructions for the software in a suitable, non-transitory computer-readable storage medium and may execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Either of video encoder <NUM> and video decoder <NUM> may be integrated as part of a combined encoder/decoder (CODEC) in a single device, for example, as shown in <FIG>.

Source device <NUM> and destination device <NUM> may comprise any of a wide range of devices, including any kind of handheld or stationary devices, e.g. notebook or laptop computers, mobile phones, smart phones, tablets or tablet computers, cameras, desktop computers, set-top boxes, televisions, display devices, digital media players, video gaming consoles, video streaming devices(such as content services servers or content delivery servers), broadcast receiver device, broadcast transmitter device, or the like and may use no or any kind of operating system. In some cases, the source device <NUM> and the destination device <NUM> may be equipped for wireless communication. Thus, the source device <NUM> and the destination device <NUM> may be wireless communication devices.

In some cases, video coding system <NUM> illustrated in <FIG> is merely an example and the techniques of the present application may apply to video coding settings (e.g., video encoding or video decoding) that do not necessarily include any data communication between the encoding and decoding devices. In other examples, data is retrieved from a local memory, streamed over a network, or the like. A video encoding device may encode and store data to memory, and/or a video decoding device may retrieve and decode data from memory. In some examples, the encoding and decoding is performed by devices that do not communicate with one another, but simply encode data to memory and/or retrieve and decode data from memory.

For convenience of description, embodiments of the application are described herein, for example, by reference to High-Efficiency Video Coding (HEVC) or to the reference software of Versatile Video coding (WC), the next generation video coding standard developed by the Joint Collaboration Team on Video Coding (JCT-VC) of ITU-T Video Coding Experts Group (VCEG) and ISO/IEC Motion Picture Experts Group (MPEG). One of ordinary skill in the art will understand that embodiments of the application are not limited to HEVC or WC.

<FIG> shows a schematic block diagram of an example video encoder <NUM> that is configured to implement the techniques of the present application. In the example of <FIG>, the video encoder <NUM> comprises an input <NUM> (or input interface <NUM>), a residual calculation unit <NUM>, a transform processing unit <NUM>, a quantization unit <NUM>, an inverse quantization unit <NUM>, and inverse transform processing unit <NUM>, a reconstruction unit <NUM>, a loop filter unit <NUM>, a decoded picture buffer (DPB) <NUM>, a mode selection unit <NUM>, an entropy encoding unit <NUM> and an output <NUM> (or output interface <NUM>). The mode selection unit <NUM> may include an inter prediction unit <NUM>, an intra prediction unit <NUM> and a partitioning unit <NUM>. Inter prediction unit <NUM> may include a motion estimation unit and a motion compensation unit (not shown). A video encoder <NUM> as shown in <FIG> may also be referred to as hybrid video encoder or a video encoder according to a hybrid video codec.

The residual calculation unit <NUM>, the transform processing unit <NUM>, the quantization unit <NUM>, the mode selection unit <NUM> may be referred to as forming a forward signal path of the encoder <NUM>, whereas the inverse quantization unit <NUM>, the inverse transform processing unit <NUM>, the reconstruction unit <NUM>, the buffer <NUM>, the loop filter <NUM>, the decoded picture buffer (DPB) <NUM>, the inter prediction unit <NUM> and the intra-prediction unit <NUM> may be referred to as forming a backward signal path of the video encoder <NUM>, wherein the backward signal path of the video encoder <NUM> corresponds to the signal path of the decoder (see video decoder <NUM> in <FIG>). The inverse quantization unit <NUM>, the inverse transform processing unit <NUM>, the reconstruction unit <NUM>, the loop filter <NUM>, the decoded picture buffer (DPB) <NUM>, the inter prediction unit <NUM> and the intra-prediction unit <NUM> are also referred to forming the "built-in decoder" of video encoder <NUM>.

The encoder <NUM> may be configured to receive, e.g. via input <NUM>, a picture <NUM> (or picture data <NUM>), e.g. picture of a sequence of pictures forming a video or video sequence. The received picture or picture data may also be a pre-processed picture <NUM> (or pre-processed picture data <NUM>). For sake of simplicity the following description refers to the picture <NUM>. The picture <NUM> may also be referred to as current picture or picture to be coded (in particular in video coding to distinguish the current picture from other pictures, e.g. previously encoded and/or decoded pictures of the same video sequence, i.e. the video sequence which also comprises the current picture).

A (digital) picture is or can be regarded as a two-dimensional array or matrix of samples with intensity values. A sample in the array may also be referred to as pixel (short form of picture element) or a pel. The number of samples in horizontal and vertical direction (or axis) of the array or picture define the size and/or resolution of the picture. For representation of color, typically three color components are employed, i.e. the picture may be represented or include three sample arrays. In RBG format or color space a picture comprises a corresponding red, green and blue sample array. However, in video coding each pixel is typically represented in a luminance and chrominance format or color space, e.g. YCbCr, which comprises a luminance component indicated by Y (sometimes also L is used instead) and two chrominance components indicated by Cb and Cr. The luminance (or short luma) component Y represents the brightness or grey level intensity (e.g. like in a grey-scale picture), while the two chrominance (or short chroma) components Cb and Cr represent the chromaticity or color information components. Accordingly, a picture in YCbCr format comprises a luminance sample array of luminance sample values (Y), and two chrominance sample arrays of chrominance values (Cb and Cr). Pictures in RGB format may be converted or transformed into YCbCr format and vice versa, the process is also known as color transformation or conversion. If a picture is monochrome, the picture may comprise only a luminance sample array. Accordingly, a picture may be, for example, an array of luma samples in monochrome format or an array of luma samples and two corresponding arrays of chroma samples in <NUM>:<NUM>:<NUM>, <NUM>:<NUM>:<NUM>, and <NUM>:<NUM>:<NUM> colour format.

Embodiments of the video encoder <NUM> may comprise a picture partitioning unit (not depicted in <FIG>) configured to partition the picture <NUM> into a plurality of (typically non-overlapping) picture blocks <NUM>. These blocks may also be referred to as root blocks, macro blocks (H. <NUM>/AVC) or coding tree blocks (CTB) or coding tree units (CTU) (H. <NUM>/HEVC and WC). The picture partitioning unit may be configured to use the same block size for all pictures of a video sequence and the corresponding grid defining the block size, or to change the block size between pictures or subsets or groups of pictures, and partition each picture into the corresponding blocks.

In further embodiments, the video encoder may be configured to receive directly a block <NUM> of the picture <NUM>, e.g. one, several or all blocks forming the picture <NUM>. The picture block <NUM> may also be referred to as current picture block or picture block to be coded.

Like the picture <NUM>, the picture block <NUM> again is or can be regarded as a two-dimensional array or matrix of samples with intensity values (sample values), although of smaller dimension than the picture <NUM>. In other words, the block <NUM> may comprise, e.g., one sample array (e.g. a luma array in case of a monochrome picture <NUM>, or a luma or chroma array in case of a color picture) or three sample arrays (e.g. a luma and two chroma arrays in case of a color picture <NUM>) or any other number and/or kind of arrays depending on the color format applied. The number of samples in horizontal and vertical direction (or axis) of the block <NUM> define the size of block <NUM>. Accordingly, a block may, for example, an MxN (M-column by N-row) array of samples, or an MxN array of transform coefficients.

Embodiments of the video encoder <NUM> as shown in <FIG> may be configured encode the picture <NUM> block by block, e.g. the encoding and prediction is performed per block <NUM>.

The residual calculation unit <NUM> may be configured to calculate a residual block <NUM> (also referred to as residual <NUM>) based on the picture block <NUM> and a prediction block <NUM> (further details about the prediction block <NUM> are provided later), e.g. by subtracting sample values of the prediction block <NUM> from sample values of the picture block <NUM>, sample by sample (pixel by pixel) to obtain the residual block <NUM> in the sample domain.

The transform processing unit <NUM> may be configured to apply a transform, e.g. a discrete cosine transform (DCT) or discrete sine transform (DST), on the sample values of the residual block <NUM> to obtain transform coefficients <NUM> in a transform domain. The transform coefficients <NUM> may also be referred to as transform residual coefficients and represent the residual block <NUM> in the transform domain.

The transform processing unit <NUM> may be configured to apply integer approximations of DCT/DST, such as the transforms specified for H. <NUM>/HEVC. Compared to an orthogonal DCT transform, such integer approximations are typically scaled by a certain factor. In order to preserve the norm of the residual block which is processed by forward and inverse transforms, additional scaling factors are applied as part of the transform process. The scaling factors are typically chosen based on certain constraints like scaling factors being a power of two for shift operations, bit depth of the transform coefficients, tradeoff between accuracy and implementation costs, etc. Specific scaling factors are, for example, specified for the inverse transform, e.g. by inverse transform processing unit <NUM> (and the corresponding inverse transform, e.g. by inverse transform processing unit <NUM> at video decoder <NUM>) and corresponding scaling factors for the forward transform, e.g. by transform processing unit <NUM>, at an encoder <NUM> may be specified accordingly.

Embodiments of the video encoder <NUM> (respectively transform processing unit <NUM>) may be configured to output transform parameters, e.g. a type of transform or transforms, e.g. directly or encoded or compressed via the entropy encoding unit <NUM>, so that, e.g., the video decoder <NUM> may receive and use the transform parameters for decoding.

The quantization unit <NUM> may be configured to quantize the transform coefficients <NUM> to obtain quantized coefficients <NUM>, e.g. by applying scalar quantization or vector quantization. The quantized coefficients <NUM> may also be referred to as quantized transform coefficients <NUM> or quantized residual coefficients <NUM>.

The quantization process may reduce the bit depth associated with some or all of the transform coefficients <NUM>. For example, an n-bit transform coefficient may be rounded down to an m-bit Transform coefficient during quantization, where n is greater than m. The degree of quantization may be modified by adjusting a quantization parameter (QP). For example for scalar quantization, different scaling may be applied to achieve finer or coarser quantization. Smaller quantization step sizes correspond to finer quantization, whereas larger quantization step sizes correspond to coarser quantization. The applicable quantization step size may be indicated by a quantization parameter (QP). The quantization parameter may for example be an index to a predefined set of applicable quantization step sizes. For example, small quantization parameters may correspond to fine quantization (small quantization step sizes) and large quantization parameters may correspond to coarse quantization (large quantization step sizes) or vice versa. The quantization may include division by a quantization step size and a corresponding and/or the inverse dequantization, e.g. by inverse quantization unit <NUM>, may include multiplication by the quantization step size. Embodiments according to some standards, e.g. HEVC, may be configured to use a quantization parameter to determine the quantization step size. Generally, the quantization step size may be calculated based on a quantization parameter using a fixed point approximation of an equation including division. Additional scaling factors may be introduced for quantization and dequantization to restore the norm of the residual block, which might get modified because of the scaling used in the fixed point approximation of the equation for quantization step size and quantization parameter. In one example implementation, the scaling of the inverse transform and dequantization might be combined. Alternatively, customized quantization tables may be used and signaled from an encoder to a decoder, e.g. in a bitstream. The quantization is a lossy operation, wherein the loss increases with increasing quantization step sizes.

Embodiments of the video encoder <NUM> (respectively quantization unit <NUM>) may be configured to output quantization parameters (QP), e.g. directly or encoded via the entropy encoding unit <NUM>, so that, e.g., the video decoder <NUM> may receive and apply the quantization parameters for decoding.

The inverse quantization unit <NUM> is configured to apply the inverse quantization of the quantization unit <NUM> on the quantized coefficients to obtain dequantized coefficients <NUM>, e.g. by applying the inverse of the quantization scheme applied by the quantization unit <NUM> based on or using the same quantization step size as the quantization unit <NUM>. The dequantized coefficients <NUM> may also be referred to as dequantized residual coefficients <NUM> and correspond - although typically not identical to the transform coefficients due to the loss by quantization - to the transform coefficients <NUM>.

The inverse transform processing unit <NUM> is configured to apply the inverse transform of the transform applied by the transform processing unit <NUM>, e.g. an inverse discrete cosine transform (DCT) or inverse discrete sine transform (DST) or other inverse transforms, to obtain a reconstructed residual block <NUM> (or corresponding dequantized coefficients <NUM>) in the sample domain. The reconstructed residual block <NUM> may also be referred to as transform block <NUM>.

The reconstruction unit <NUM> (e.g. adder or summer <NUM>) is configured to add the transform block <NUM> (i.e. reconstructed residual block <NUM>) to the prediction block <NUM> to obtain a reconstructed block <NUM> in the sample domain, e.g. by adding - sample by sample - the sample values of the reconstructed residual block <NUM> and the sample values of the prediction block <NUM>.

The loop filter unit <NUM> (or short "loop filter" <NUM>), is configured to filter the reconstructed block <NUM> to obtain a filtered block <NUM>, or in general, to filter reconstructed samples to obtain filtered samples. The loop filter unit is, e.g., configured to smooth pixel transitions, or otherwise improve the video quality. The loop filter unit <NUM> may comprise one or more loop filters such as a de-blocking filter, a sample-adaptive offset (SAO) filter or one or more other filters, e.g. a bilateral filter, an adaptive loop filter (ALF), a sharpening, a smoothing filters or a collaborative filters, or any combination thereof. Although the loop filter unit <NUM> is shown in <FIG> as being an in loop filter, in other configurations, the loop filter unit <NUM> may be implemented as a post loop filter. The filtered block <NUM> may also be referred to as filtered reconstructed block <NUM>.

Embodiments of the video encoder <NUM> (respectively loop filter unit <NUM>) may be configured to output loop filter parameters (such as sample adaptive offset information), e.g. directly or encoded via the entropy encoding unit <NUM>, so that, e.g., a decoder <NUM> may receive and apply the same loop filter parameters or respective loop filters for decoding.

The decoded picture buffer (DPB) <NUM> may be a memory that stores reference pictures, or in general reference picture data, for encoding video data by video encoder <NUM>. The DPB <NUM> may be formed by any of a variety of memory devices, such as dynamic random access memory (DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The decoded picture buffer (DPB) <NUM> may be configured to store one or more filtered blocks <NUM>. The decoded picture buffer <NUM> may be further configured to store other previously filtered blocks, e.g. previously reconstructed and filtered blocks <NUM>, of the same current picture or of different pictures, e.g. previously reconstructed pictures, and may provide complete previously reconstructed, i.e. decoded, pictures (and corresponding reference blocks and samples) and/or a partially reconstructed current picture (and corresponding reference blocks and samples), for example for inter prediction. The decoded picture buffer (DPB) <NUM> may be also configured to store one or more unfiltered reconstructed blocks <NUM>, or in general unfiltered reconstructed samples, e.g. if the reconstructed block <NUM> is not filtered by loop filter unit <NUM>, or any other further processed version of the reconstructed blocks or samples.

The mode selection unit <NUM> comprises partitioning unit <NUM>, inter-prediction unit <NUM> and intra-prediction unit <NUM>, and is configured to receive or obtain original picture data, e.g. an original block <NUM> (current block <NUM> of the current picture <NUM>), and reconstructed picture data, e.g. filtered and/or unfiltered reconstructed samples or blocks of the same (current) picture and/or from one or a plurality of previously decoded pictures, e.g. from decoded picture buffer <NUM> or other buffers (e.g. line buffer, not shown). The reconstructed picture data is used as reference picture data for prediction, e.g. inter-prediction or intra-prediction, to obtain a prediction block <NUM> or predictor <NUM>. Mode selection unit <NUM> may be configured to determine or select a partitioning for a current block prediction mode (including no partitioning) and a prediction mode (e.g. an intra or inter prediction mode) and generate a corresponding prediction block <NUM>, which is used for the calculation of the residual block <NUM> and for the reconstruction of the reconstructed block <NUM>.

Embodiments of the mode selection unit <NUM> may be configured to select the partitioning and the prediction mode (e.g. from those supported by or available for mode selection unit <NUM>), which provide the best match or in other words the minimum residual (minimum residual means better compression for transmission or storage), or a minimum signaling overhead (minimum signaling overhead means better compression for transmission or storage), or which considers or balances both. The mode selection unit <NUM> may be configured to determine the partitioning and prediction mode based on rate distortion optimization (RDO), i.e. select the prediction mode which provides a minimum rate distortion. Terms like "best", "minimum", "optimum" etc. in this context do not necessarily refer to an overall "best", "minimum", "optimum", etc. but may also refer to the fulfillment of a termination or selection criterion like a value exceeding or falling below a threshold or other constraints leading potentially to a "sub-optimum selection" but reducing complexity and processing time.

In other words, the partitioning unit <NUM> may be configured to partition the block <NUM> into smaller block partitions or sub-blocks (which form again blocks), e.g. iteratively using quad-tree-partitioning (QT), binary partitioning (BT) or triple-tree-partitioning (TT) or any combination thereof, and to perform, e.g., the prediction for each of the block partitions or sub-blocks, wherein the mode selection comprises the selection of the tree-structure of the partitioned block <NUM> and the prediction modes are applied to each of the block partitions or sub-blocks.

In the following the partitioning (e.g. by partitioning unit <NUM>) and prediction processing (by inter-prediction unit <NUM> and intra-prediction unit <NUM>) performed by an example video encoder <NUM> will be explained in more detail.

The partitioning unit <NUM> may partition (or split) a current block <NUM> into smaller partitions, e.g. smaller blocks of square or rectangular size. These smaller blocks (which may also be referred to as sub-blocks) may be further partitioned into even smaller partitions. This is also referred to tree-partitioning or hierarchical tree-partitioning, wherein a root block, e.g. at root tree-level <NUM> (hierarchy-level <NUM>, depth <NUM>), may be recursively partitioned, e.g. partitioned into two or more blocks of a next lower tree-level, e.g. nodes at tree-level <NUM> (hierarchy-level <NUM>, depth <NUM>), wherein these blocks may be again partitioned into two or more blocks of a next lower level, e.g. tree-level <NUM> (hierarchy-level <NUM>, depth <NUM>), etc. until the partitioning is terminated, e.g. because a termination criterion is fulfilled, e.g. a maximum tree depth or minimum block size is reached. Blocks which are not further partitioned are also referred to as leaf-blocks or leaf nodes of the tree. A tree using partitioning into two partitions is referred to as binary-tree (BT), a tree using partitioning into three partitions is referred to as ternary-tree (TT), and a tree using partitioning into four partitions is referred to as quad-tree (QT).

As mentioned before, the term "block" as used herein may be a portion, in particular a square or rectangular portion, of a picture. With reference, for example, to HEVC and VVC, the block may be or correspond to a coding tree unit (CTU), a coding unit (CU), prediction unit (PU), and transform unit (TU) and/or to the corresponding blocks, e.g. a coding tree block (CTB), a coding block (CB), a transform block (TB) or prediction block (PB).

For example, a coding tree unit (CTU) may be or comprise a CTB of luma samples, two corresponding CTBs of chroma samples of a picture that has three sample arrays, or a CTB of samples of a monochrome picture or a picture that is coded using three separate colour planes and syntax structures used to code the samples. Correspondingly, a coding tree block (CTB) may be an NoN block of samples for some value of N such that the division of a component into CTBs is a partitioning. A coding unit (CU) may be or comprise a coding block of luma samples, two corresponding coding blocks of chroma samples of a picture that has three sample arrays, or a coding block of samples of a monochrome picture or a picture that is coded using three separate colour planes and syntax structures used to code the samples. Correspondingly a coding block (CB) may be an MxN block of samples for some values of M and N such that the division of a CTB into coding blocks is a partitioning.

In embodiments, e.g., according to HEVC, a coding tree unit (CTU) may be split into CUs by using a quad-tree structure denoted as coding tree. The decision whether to code a picture area using inter-picture (temporal) or intra-picture (spatial) prediction is made at the CU level. Each CU can be further split into one, two or four PUs according to the PU splitting type. Inside one PU, the same prediction process is applied and the relevant information is transmitted to the decoder on a PU basis. After obtaining the residual block by applying the prediction process based on the PU splitting type, a CU can be partitioned into transform units (TUs) according to another quadtree structure similar to the coding tree for the CU.

In embodiments, e.g., according to the latest video coding standard currently in development, which is referred to as Versatile Video Coding (WC), Quad-tree and binary tree (QTBT) partitioning is used to partition a coding block. In the QTBT block structure, a CU can have either a square or rectangular shape. For example, a coding tree unit (CTU) is first partitioned by a quadtree structure. The quadtree leaf nodes are further partitioned by a binary tree or ternary (or triple) tree structure. The partitioning tree leaf nodes are called coding units (CUs), and that segmentation is used for prediction and transform processing without any further partitioning. This means that the CU, PU and TU have the same block size in the QTBT coding block structure. In parallel, multiple partition, for example, triple tree partition was also proposed to be used together with the QTBT block structure.

In one example, the mode selection unit <NUM> of video encoder <NUM> may be configured to perform any combination of the partitioning techniques described herein.

As described above, the video encoder <NUM> is configured to determine or select the best or an optimum prediction mode from a set of (pre-determined) prediction modes. The set of prediction modes may comprise, e.g., intra-prediction modes and/or inter-prediction modes.

The set of intra-prediction modes may comprise <NUM> different intra-prediction modes, e.g. non-directional modes like DC (or mean) mode and planar mode, or directional modes, e.g. as defined in HEVC, or may comprise <NUM> different intra-prediction modes, e.g. non-directional modes like DC (or mean) mode and planar mode, or directional modes, e.g. as defined for WC.

The intra-prediction unit <NUM> is configured to use reconstructed samples of neighboring blocks of the same current picture to generate an intra-prediction block <NUM> according to an intra-prediction mode of the set of intra-prediction modes.

The intra prediction unit <NUM> (or in general the mode selection unit <NUM>) is further configured to output intra-prediction parameters (or in general information indicative of the selected intra prediction mode for the block) to the entropy encoding unit <NUM> in form of syntax elements <NUM> for inclusion into the encoded picture data <NUM>, so that, e.g., the video decoder <NUM> may receive and use the prediction parameters for decoding.

The set of (or possible) inter-prediction modes depends on the available reference pictures (i.e. previous at least partially decoded pictures, e.g. stored in DBP <NUM>) and other inter-prediction parameters, e.g. whether the whole reference picture or only a part, e.g. a search window area around the area of the current block, of the reference picture is used for searching for a best matching reference block, and/or e.g. whether pixel interpolation is applied, e.g. half/semi-pel and/or quarter-pel interpolation, or not.

Additional to the above prediction modes, skip mode and/or direct mode may be applied.

The inter prediction unit <NUM> may include a motion estimation (ME) unit and a motion compensation (MC) unit (both not shown in <FIG>). The motion estimation unit may be configured to receive or obtain the picture block <NUM> (current picture block <NUM> of the current picture <NUM>) and a decoded picture <NUM>, or at least one or a plurality of previously reconstructed blocks, e.g. reconstructed blocks of one or a plurality of other/different previously decoded pictures <NUM>, for motion estimation. a video sequence may comprise the current picture and the previously decoded pictures <NUM>, or in other words, the current picture and the previously decoded pictures <NUM> may be part of or form a sequence of pictures forming a video sequence.

The encoder <NUM> may, e.g., be configured to select a reference block from a plurality of reference blocks of the same or different pictures of the plurality of other pictures and provide a reference picture (or reference picture index) and/or an offset (spatial offset) between the position (x, y coordinates) of the reference block and the position of the current block as inter prediction parameters to the motion estimation unit. This offset is also called motion vector (MV).

The motion compensation unit is configured to obtain, e.g. receive, an inter prediction parameter and to perform inter prediction based on or using the inter prediction parameter to obtain an inter prediction block <NUM>. Motion compensation, performed by the motion compensation unit, may involve fetching or generating the prediction block based on the motion/block vector determined by motion estimation, possibly performing interpolations to sub-pixel precision. Interpolation filtering may generate additional pixel samples from known pixel samples, thus potentially increasing the number of candidate prediction blocks that may be used to code a picture block. Upon receiving the motion vector for the PU of the current picture block, the motion compensation unit may locate the prediction block to which the motion vector points in one of the reference picture lists.

Motion compensation unit may also generate syntax elements associated with the blocks and the video slice for use by video decoder <NUM> in decoding the picture blocks of the video slice.

The entropy encoding unit <NUM> is configured to apply, for example, an entropy encoding algorithm or scheme (e.g. a variable length coding (VLC) scheme, an context adaptive VLC scheme (CAVLC), an arithmetic coding scheme, a binarization, a context adaptive binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding or another entropy encoding methodology or technique) or bypass (no compression) on the quantized coefficients <NUM>, inter prediction parameters, intra prediction parameters, loop filter parameters and/or other syntax elements to obtain encoded picture data <NUM> which can be output via the output <NUM>, e.g. in the form of an encoded bitstream <NUM>, so that, e.g., the video decoder <NUM> may receive and use the parameters for decoding,. The encoded bitstream <NUM> may be transmitted to video decoder <NUM>, or stored in a memory for later transmission or retrieval by video decoder <NUM>.

Other structural variations of the video encoder <NUM> can be used to encode the video stream. For example, a non-transform based encoder <NUM> can quantize the residual signal directly without the transform processing unit <NUM> for certain blocks or frames. In another implementation, an encoder <NUM> can have the quantization unit <NUM> and the inverse quantization unit <NUM> combined into a single unit.

<FIG> shows an example of a video decoder <NUM> that is configured to implement the techniques of this present application. The video decoder <NUM> is configured to receive encoded picture data <NUM> (e.g. encoded bitstream <NUM>), e.g. encoded by encoder <NUM>, to obtain a decoded picture <NUM>. The encoded picture data or bitstream comprises information for decoding the encoded picture data, e.g. data that represents picture blocks of an encoded video slice and associated syntax elements.

In the example of <FIG>, the decoder <NUM> comprises an entropy decoding unit <NUM>, an inverse quantization unit <NUM>, an inverse transform processing unit <NUM>, a reconstruction unit <NUM> (e.g. a summer <NUM>), a loop filter <NUM>, a decoded picture buffer (DBP) <NUM>, an inter prediction unit <NUM> and an intra prediction unit <NUM>. Inter prediction unit <NUM> may be or include a motion compensation unit. Video decoder <NUM> may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder <NUM> from <FIG>.

As explained with regard to the encoder <NUM>, the inverse quantization unit <NUM>, the inverse transform processing unit <NUM>, the reconstruction unit <NUM> the loop filter <NUM>, the decoded picture buffer (DPB) <NUM>, the inter prediction unit <NUM> and the intra prediction unit <NUM> are also referred to as forming the "built-in decoder" of video encoder <NUM>. Accordingly, the inverse quantization unit <NUM> may be identical in function to the inverse quantization unit <NUM>, the inverse transform processing unit <NUM> may be identical in function to the inverse transform processing unit <NUM>, the reconstruction unit <NUM> may be identical in function to reconstruction unit <NUM>, the loop filter <NUM> may be identical in function to the loop filter <NUM>, and the decoded picture buffer <NUM> may be identical in function to the decoded picture buffer <NUM>. Therefore, the explanations provided for the respective units and functions of the video <NUM> encoder apply correspondingly to the respective units and functions of the video decoder <NUM>.

The entropy decoding unit <NUM> is configured to parse the bitstream <NUM> (or in general encoded picture data <NUM>) and perform, for example, entropy decoding to the encoded picture data <NUM> to obtain, e.g., quantized coefficients <NUM> and/or decoded coding parameters (not shown in <FIG>), e.g. any or all of inter prediction parameters (e.g. reference picture index and motion vector), intra prediction parameter (e.g. intra prediction mode or index), transform parameters, quantization parameters, loop filter parameters, and/or other syntax elements. Entropy decoding unit <NUM> maybe configured to apply the decoding algorithms or schemes corresponding to the encoding schemes as described with regard to the entropy encoding unit <NUM> of the encoder <NUM>. Entropy decoding unit <NUM> may be further configured to provide inter prediction parameters, intra prediction parameter and/or other syntax elements to the mode selection unit <NUM> and other parameters to other units of the decoder <NUM>. Video decoder <NUM> may receive the syntax elements at the video slice level and/or the video block level.

The inverse quantization unit <NUM> may be configured to receive quantization parameters (QP) (or in general information related to the inverse quantization) and quantized coefficients from the encoded picture data <NUM> (e.g. by parsing and/or decoding, e.g. by entropy decoding unit <NUM>) and to apply based on the quantization parameters an inverse quantization on the decoded quantized coefficients <NUM> to obtain dequantized coefficients <NUM>, which may also be referred to as transform coefficients <NUM>. The inverse quantization process may include use of a quantization parameter determined by video encoder <NUM> for each video block in the video slice to determine a degree of quantization and, likewise, a degree of inverse quantization that should be applied.

Inverse transform processing unit <NUM> may be configured to receive dequantized coefficients <NUM>, also referred to as transform coefficients <NUM>, and to apply a transform to the dequantized coefficients <NUM> in order to obtain reconstructed residual blocks <NUM> in the sample domain. The reconstructed residual blocks <NUM> may also be referred to as transform blocks <NUM>. The transform may be an inverse transform, e.g., an inverse DCT, an inverse DST, an inverse integer transform, or a conceptually similar inverse transform process. The inverse transform processing unit <NUM> may be further configured to receive transform parameters or corresponding information from the encoded picture data <NUM> (e.g. by parsing and/or decoding, e.g. by entropy decoding unit <NUM>) to determine the transform to be applied to the dequantized coefficients <NUM>.

The reconstruction unit <NUM> (e.g. adder or summer <NUM>) may be configured to add the reconstructed residual block <NUM>, to the prediction block <NUM> to obtain a reconstructed block <NUM> in the sample domain, e.g. by adding the sample values of the reconstructed residual block <NUM> and the sample values of the prediction block <NUM>.

The loop filter unit <NUM> (either in the coding loop or after the coding loop) is configured to filter the reconstructed block <NUM> to obtain a filtered block <NUM>, e.g. to smooth pixel transitions, or otherwise improve the video quality. The loop filter unit <NUM> may comprise one or more loop filters such as a de-blocking filter, a sample-adaptive offset (SAO) filter or one or more other filters, e.g. a bilateral filter, an adaptive loop filter (ALF), a sharpening, a smoothing filters or a collaborative filters, or any combination thereof. Although the loop filter unit <NUM> is shown in <FIG> as being an in loop filter, in other configurations, the loop filter unit <NUM> may be implemented as a post loop filter.

The decoded video blocks <NUM> of a picture are then stored in decoded picture buffer <NUM>, which stores the decoded pictures <NUM> as reference pictures for subsequent motion compensation for other pictures and/or for output respectively display.

The decoder <NUM> is configured to output the decoded picture <NUM>, e.g. via output <NUM>, for presentation or viewing to a user.

The inter prediction unit <NUM> may be identical to the inter prediction unit <NUM> (in particular to the motion compensation unit) and the intra prediction unit <NUM> may be identical to the inter prediction unit <NUM> in function, and performs split or partitioning decisions and prediction based on the partitioning and/or prediction parameters or respective information received from the encoded picture data <NUM> (e.g. by parsing and/or decoding, e.g. by entropy decoding unit <NUM>). Mode selection unit <NUM> may be configured to perform the prediction (intra or inter prediction) per block based on reconstructed pictures, blocks or respective samples (filtered or unfiltered) to obtain the prediction block <NUM>.

When the video slice is coded as an intra coded (I) slice, intra prediction unit <NUM> of mode selection unit <NUM> is configured to generate prediction block <NUM> for a picture block of the current video slice based on a signaled intra prediction mode and data from previously decoded blocks of the current picture. When the video picture is coded as an inter coded (i.e., B, or P) slice, inter prediction unit <NUM> (e.g. motion compensation unit) of mode selection unit <NUM> is configured to produce prediction blocks <NUM> for a video block of the current video slice based on the motion vectors and other syntax elements received from entropy decoding unit <NUM>. For inter prediction, the prediction blocks may be produced from one of the reference pictures within one of the reference picture lists. Video decoder <NUM> may construct the reference frame lists, List <NUM> and List <NUM>, using default construction techniques based on reference pictures stored in DPB <NUM>.

Mode selection unit <NUM> is configured to determine the prediction information for a video block of the current video slice by parsing the motion vectors and other syntax elements, and uses the prediction information to produce the prediction blocks for the current video block being decoded. For example, the mode selection unit <NUM> uses some of the received syntax elements to determine a prediction mode (e.g., intra or inter prediction) used to code the video blocks of the video slice, an inter prediction slice type (e.g., B slice, P slice, or GPB slice), construction information for one or more of the reference picture lists for the slice, motion vectors for each inter encoded video block of the slice, inter prediction status for each inter coded video block of the slice, and other information to decode the video blocks in the current video slice.

Other variations of the video decoder <NUM> can be used to decode the encoded picture data <NUM>. For example, the decoder <NUM> can produce the output video stream without the loop filtering unit <NUM>. For example, a non-transform based decoder <NUM> can inverse-quantize the residual signal directly without the inverse-transform processing unit <NUM> for certain blocks or frames. In another implementation, the video decoder <NUM> can have the inverse-quantization unit <NUM> and the inverse-transform processing unit <NUM> combined into a single unit.

It should be understood that, in the encoder <NUM> and the decoder <NUM>, a processing result of a current step may be further processed and then output to the next step. For example, after interpolation filtering, motion vector derivation or loop filtering, a further operation, such as Clip or shift, may be performed on the processing result of the interpolation filtering, motion vector derivation or loop filtering.

It should be noted that further operations may be applied to the derived motion vectors of current block (including but not limit to control point motion vectors of affine mode, sub-block motion vectors in affine, planar, ATMVP modes, temporal motion vectors, and so on). For example, the value of motion vector is constrained to a predefined range according to its representing bit. If the representing bit of motion vector is bitDepth, then the range is - <NUM>^(bitDepth-<NUM>) ~ <NUM>^(bitDepth-<NUM>)-<NUM>, where "^" means exponentiation. For example, if bitDepth is set equal to <NUM>, the range is -<NUM> ~ <NUM>; if bitDepth is set equal to <NUM>, the range is -<NUM>~<NUM>. Here provides two methods for constraining the motion vector.

Method <NUM>: remove the overflow MSB (most significant bit) by flowing operations <MAT> <MAT> <MAT> <MAT>.

For example, if the value of mvx is -<NUM>, after applying formula (<NUM>) and (<NUM>), the resulting value is <NUM>. In computer system, decimal numbers are stored as two's complement. The two's complement of -<NUM> is <NUM>,<NUM>,<NUM>,<NUM>,<NUM> (<NUM> bits), then the MSB is discarded, so the resulting two's complement is <NUM>,<NUM>,<NUM>,<NUM> (decimal number is <NUM>), which is same as the output by applying formula (<NUM>) and (<NUM>). <MAT> <MAT> <MAT> <MAT>.

The operations may be applied during the sum of mvp and mvd, as shown in formula (<NUM>) to (<NUM>). Method <NUM>: remove the overflow MSB by clipping the value <MAT> <MAT> where the definition of function Clip3 is as follow: <MAT>.

<FIG> is a schematic diagram of a video coding device <NUM> according to an embodiment of the disclosure. The video coding device <NUM> is suitable for implementing the disclosed embodiments as described herein. In an embodiment, the video coding device <NUM> may be a decoder such as video decoder <NUM> of <FIG> or an encoder such as video encoder <NUM> of <FIG>.

The video coding device <NUM> comprises ingress ports <NUM> (or input ports <NUM>) and receiver units (Rx) <NUM> for receiving data; a processor, logic unit, or central processing unit (CPU) <NUM> to process the data; transmitter units (Tx) <NUM> and egress ports <NUM> (or output ports <NUM>) for transmitting the data; and a memory <NUM> for storing the data. The video coding device <NUM> may also comprise optical-to-electrical (OE) components and electrical-to-optical (EO) components coupled to the ingress ports <NUM>, the receiver units <NUM>, the transmitter units <NUM>, and the egress ports <NUM> for egress or ingress of optical or electrical signals.

The processor <NUM> is implemented by hardware and software. The processor <NUM> may be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), FPGAs, ASICs, and DSPs. The processor <NUM> is in communication with the ingress ports <NUM>, receiver units <NUM>, transmitter units <NUM>, egress ports <NUM>, and memory <NUM>. The processor <NUM> comprises a coding module <NUM>. The coding module <NUM> implements the disclosed embodiments described above. For instance, the coding module <NUM> implements, processes, prepares, or provides the various coding operations. The inclusion of the coding module <NUM> therefore provides a substantial improvement to the functionality of the video coding device <NUM> and effects a transformation of the video coding device <NUM> to a different state. Alternatively, the coding module <NUM> is implemented as instructions stored in the memory <NUM> and executed by the processor <NUM>.

The memory <NUM> may comprise one or more disks, tape drives, and solid-state drives and may be used as an overflow data storage device, to store programs when such programs are selected for execution, and to store instructions and data that are read during program execution. The memory <NUM> may be, for example, volatile and/or non-volatile and may be a read-only memory (ROM), random access memory (RAM), ternary content-addressable memory (TCAM), and/or static random-access memory (SRAM).

<FIG> is a simplified block diagram of an apparatus <NUM> that may be used as either or both of the source device <NUM> and the destination device <NUM> from <FIG> according to an exemplary embodiment.

A processor <NUM> in the apparatus <NUM> can be a central processing unit. Alternatively, the processor <NUM> can be any other type of device, or multiple devices, capable of manipulating or processing information now-existing or hereafter developed. Although the disclosed implementations can be practiced with a single processor as shown, e.g., the processor <NUM>, advantages in speed and efficiency can be achieved using more than one processor.

A memory <NUM> in the apparatus <NUM> can be a read only memory (ROM) device or a random access memory (RAM) device in an implementation. Any other suitable type of storage device can be used as the memory <NUM>. The memory <NUM> can include code and data <NUM> that is accessed by the processor <NUM> using a bus <NUM>. The memory <NUM> can further include an operating system <NUM> and application programs <NUM>, the application programs <NUM> including at least one program that permits the processor <NUM> to perform the methods described here. For example, the application programs <NUM> can include applications <NUM> through N, which further include a video coding application that performs the methods described here.

The apparatus <NUM> can also include one or more output devices, such as a display <NUM>. The display <NUM> may be, in one example, a touch sensitive display that combines a display with a touch sensitive element that is operable to sense touch inputs. The display <NUM> can be coupled to the processor <NUM> via the bus <NUM>.

Although depicted here as a single bus, the bus <NUM> of the apparatus <NUM> can be composed of multiple buses. Further, the secondary storage <NUM> can be directly coupled to the other components of the apparatus <NUM> or can be accessed via a network and can comprise a single integrated unit such as a memory card or multiple units such as multiple memory cards. The apparatus <NUM> can thus be implemented in a wide variety of configurations.

Precision of MV derived by calculation of intermediate values of motion vectors in affine prediction was increased from ¼ in pixel length to <NUM>/<NUM>th. This increase of precision cause the memory storage capacity for motion vector field up to <NUM> bit per motion vector component. During video codec development each MV was stored with the granularity 4x4 pixels. Later few attempts has been made to reduce memory capacity for storing motion vector information. One of proposals about granularity reduction to the grid size 8x8 was adopted. Another attempt to reduce MV precision (for temporal MV storage or the local line buffer or both) has been made in [JVET-L0168] by simple removal of MSB (most significant bits) from motion vector component values, which lead to reduction of mv representing range which could reduce the efficiency of prediction and compression of large size pictures and <NUM>° video. Such <NUM>-bit representation of <NUM>/<NUM>th precision motion vector is not enough for <NUM> or higher resolution video coding. The two other solutions proposes to remove LSB from MV components for both horizontal and vertical direction and it was attempt to remove MSB/LSB adaptively with additional <NUM> bit for signaling.

The purpose of this invention is to provide the solution/method and a device which may reduce memory capacity in storing information for deriving a temporal motion vector prediction with keeping motion vector representation and precision in reasonable range. Keeping the precision in a reasonable range implies some reduction of the precision, resulting in some distortion of the representation. Therefore, a result of the conversion to a floating point representation is a distorted/quantized/rounded value of the MV.

Currently available solutions operate with <NUM>-bit values of each MV component for storage with reference frame (<FIG>, top). It is lead to memory increase for storing MVs by <NUM>% for HW and by <NUM>% for SW. This invention propose to use <NUM>-bit binary floating point representation of MV components values for storage within reference frame instead of <NUM> bits. However, the <NUM> bit floating point representation is an example and the invention also includes representations with less than <NUM> bit (a <NUM> bit representation, for example). Moreover, for the embodiment <NUM> where MSB are used as exponent part of floating number - there are no change in codec processing in respect to current solution when picture resolution is small.

The basic concept of the invention is <NUM> bit binary floating point representation of MV components values for storage within reference frame instead of <NUM> bits.

To reduce memory capacity for storing temporal MVs keeping MV representation and precision in reasonable range.

In order to solve the above problems, the following unclaimed aspects are disclosed, each of them can be applied individually and some of them can be applied in combination:.

Furthermore, the invention proposes to use <NUM>-bit binary representation of MV components values for storage within reference frame instead of <NUM> bits, wherein <NUM>-bit values can be obtained from the <NUM>-bit values by removing <NUM> LSB (least significant bits) or <NUM> MSB (most significant bits) depending on value signaled in the bitstream. The signaling can be by the predefined signaling mechanism as described in [JVET-L0168].

To reduce memory capacity for storing temporal MVs keeping MV representation and precision in reasonable range. In order to solve the above problems, the following aspects are disclosed, wherein aspect <NUM> is the only aspect falling under the scope of protection, each of them can be applied individually and some of them can be applied in combination:
<NUM>. Prior to saving MV to the motion buffer, MV components are converted from <NUM>-bit binary representation to <NUM>-bit representation, using one of the following methods, depending on value signaled in bitstream:.

Restoration of MV components (converting from <NUM>-bit to <NUM>-bit binary representation) is performed using following rules:.

<FIG> shows a flow diagram of a general motion vector compression method according to the invention. The method comprises a step <NUM> of obtaining a temporal motion vector; a step <NUM> of determining a compressed motion vector using a binary representation of the temporal motion vector, wherein the binary representation comprises an exponent part and/or a mantissa part, and wherein the exponent part comprises N bits, the mantissa part comprises M bits, and wherein N is a non-negative integer and M is a positive integer; and a step <NUM> of performing a temporal motion vector prediction (TMVP) using the compressed motion vector.

Although embodiments of the application have been primarily described based on video coding, it should be noted that embodiments of the coding system <NUM>, encoder <NUM> and decoder <NUM> (and correspondingly the system <NUM>) and the other embodiments described herein may also be configured for still picture processing or coding, i.e. the processing or coding of an individual picture independent of any preceding or consecutive picture as in video coding. In general only inter-prediction units <NUM> (encoder) and <NUM> (decoder) may not be available in case the picture processing coding is limited to a single picture <NUM>. All other functionalities (also referred to as tools or technologies) of the video encoder <NUM> and video decoder <NUM> may equally be used for still picture processing, e.g. residual calculation <NUM>/<NUM>, transform <NUM>, quantization <NUM>, inverse quantization <NUM>/<NUM>, (inverse) transform <NUM>/<NUM>, partitioning <NUM>/<NUM>, intra-prediction <NUM>/<NUM>, and/or loop filtering <NUM>, <NUM>, and entropy coding <NUM> and entropy decoding <NUM>. Embodiments, e.g. of the encoder <NUM> and the decoder <NUM>, and functions described herein, e.g. with reference to the encoder <NUM> and the decoder <NUM>, may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium or transmitted over communication media as one or more instructions or code and executed by a hardware-based processing unit.

By way of example, and not limitating, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

For reference, the following logical operators are defined as follows:.

For reference, the following relational operators are defined as follows:.

When a relational operator is applied to a syntax element or variable that has been assigned the value "na" (not applicable), the value "na" is treated as a distinct value for the syntax element or variable. The value "na" is considered not to be equal to any other value.

For reference, the following bit-wise operators are defined as follows:.

Claim 1:
A motion vector compression method, comprising:
obtaining (<NUM>) a <NUM>-bit temporal motion vector;
determining (<NUM>) a <NUM>-bit compressed motion vector using a binary representation of the obtained temporal motion vector, wherein the compressed motion vector is determined by removing <NUM> least significant bits, LSB, or most significant bits, MSB, depending on a value signaled in the bitstream; and
performing (<NUM>) a temporal motion vector prediction, TMVP, using the compressed motion vector.