RU2786626C2 - Method and device for image separation - Google Patents

Abstract

FIELD: video encoding.

SUBSTANCE: group of inventions relates to the field of video encoding, namely to image separation technologies. A method for image separation is proposed. The method includes: determination of a mode of separation of the current node, where the current node includes a brightness block and a chromaticity block. Next, it is determined, based on the mode of separation of the current node and a size of the current node, that the chromaticity block of the current node is not additionally separated. The brightness block of the current node is separated based on the mode of separation of the current node.

EFFECT: reduction in throughput capacity of codec due to determination of separation of the current node.

45 cl, 16 dwg, 2 tbl

Description

The field of technology to which the invention belongs

The present invention relates to the field of video coding, and more specifically, to a method and device for dividing an image (picture partition).

State of the art

At present, Internet technologies are continuously improving, the material and spiritual culture of people is increasingly enriched, and the need for video applications, especially high-definition video, on the Internet is increasing. However, HD video contains quite a large amount of data. To transmit high-definition video on the Internet with limited bandwidth, you must first solve the technical problem associated with encoding and decoding video. Video encoding is used in a wide range of digital video applications, such as digital broadcast television, video transmission over the Internet and mobile networks, real-time conversational applications such as video chat and video conferencing, DVD and Blu-ray discs, content collection and editing systems. video and security camera applications.

Each picture of a video sequence is usually divided into a set of non-overlapping blocks, and encoding is usually done at the block level. For example, a prediction block is generated by spatial (inner image) prediction and/or temporal (outer) prediction. Accordingly, the prediction mode may include an intra prediction mode (spatial prediction) and an inter prediction mode (temporal prediction). The set of intra prediction modes may include 35 different intra prediction modes, such as non-directional modes such as DC (or averaged) mode and planar mode, or directional modes defined in H.265; or may include 67 different intra prediction modes, such as non-directional modes such as DC (or averaged) mode and planar mode, or directional modes defined in H.266 under development. The set of inter prediction modes depends on the available reference picture and another inter prediction parameter, such as whether the entire reference picture is used or only part of the reference picture.

The video currently in use is typically color video and includes a chrominance component in addition to a luminance component. Therefore, in addition to encoding and decoding the luma component, it is also necessary to encode and decode the chrominance component. However, the efficiency of encoding and decoding in the conventional technology is relatively low.

The essence of the invention

Embodiments of the present invention (or this disclosure) provide an apparatus and method for dividing an image.

According to a first aspect, an embodiment of the present invention relates to an image division method. The method is performed by a device for decoding or encoding a video stream. The method includes: determining a split mode of the current node, where the current node includes a luminance block and a chrominance block; determining, based on the split mode of the current node and the size of the current node, that the chrominance block of the current node is not further split; and, when the current node's chrominance block is no longer split, splitting the current node's luminance block based on the splitting mode of the current node.

According to the method in the first aspect, when the chrominance block of the current node is not further divided, only the luminance block of the current node can be divided, thereby improving encoding and decoding efficiency, reducing the maximum bandwidth of the codec, and facilitating the implementation of the codec.

According to a second aspect, an embodiment of the present invention relates to a device for decoding a video stream, including a processor and a memory. An instruction is stored in the memory, and the instruction enables the processor to execute the method according to the first aspect.

According to a third aspect, an embodiment of the present invention relates to a video stream encoding apparatus including a processor and a memory. An instruction is stored in the memory, and the instruction enables the processor to execute the method according to the first aspect.

According to a fourth aspect, a computer-readable storage medium is provided. A computer-readable storage medium stores an instruction; and when the instruction is executed, one or more processors are configured to encode the video data. The instruction allows one or more processors to execute the method according to any possible embodiment of the first aspect.

According to a fifth aspect, an embodiment of the present invention relates to a computer program including a program code. When the program code is executed on the computer, the method according to any possible embodiment of the first aspect is executed.

The accompanying drawings and the following descriptions provide details of one or more embodiments. Other features, objects and advantages will be apparent from the description, drawings and claims.

Brief description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present invention or the prior art, the following describes the accompanying drawings to describe the embodiments of the present invention or the prior art.

Fig. 1A is a block diagram of an example of a video coding system for implementing an embodiment of the present invention;

fig. 1B is a block diagram of an example of a video coding system including one or two encoders 20 in FIG. 2 and decoder 30 in FIG. 3;

fig. 2 is a block diagram showing an exemplary structure of a video encoder for implementing an embodiment of the present invention;

fig. 3 is a block diagram showing an exemplary structure of a video decoder for implementing an embodiment of the present invention;

fig. 4 is a block diagram illustrating an example of an encoding device or a decoding device;

fig. 5 is a block diagram illustrating an example of another encoding device or another decoding device;

fig. 6 shows an example of an exemplary grid in YUV format;

fig. 7A-fig. 7E show five different types of separation;

fig. 8 shows the quadtree plus binary tree split mode;

fig. 9 is a flowchart of a method according to the first embodiment of the present invention;

fig. 10 is a flowchart of step 906 in Embodiment 1 of the present invention; and

fig. 11 shows a flowchart of a method according to a third embodiment of the present invention.

In the following, identical reference numerals represent identical or at least functionally equivalent features, unless otherwise indicated.

Description of Embodiments

Video coding generally refers to the processing of a sequence of images that form a video or video sequence. In the field of video coding, the terms "image (picture)", "frame (frame)" and "image (image)" can be used interchangeably. The video coding used in the present invention (or the present disclosure) refers to video coding or video decoding. Video encoding is performed at the source side, for example by processing (eg, by compressing) the raw video images to reduce the amount of data required to represent the video images for more efficient storage and/or transmission. The video decoding is performed on the destination side and usually involves inverse processing compared to the encoder to recover the video images. "Coding" of video images in the embodiments should be understood as "coding" or "decoding" of a video sequence. The combination of encoding components and decoding components is also called a codec (encoding and decoding).

Each picture of a video sequence is usually divided into a set of non-overlapping blocks, and encoding is usually done at the block level. In other words, at the encoder side, the video is usually processed, i.e., encoded at the block level (which is also called a picture block or video block), for example, using spatial (inner picture) prediction and/or temporal (outer picture) prediction to generate a prediction block. , subtracting the prediction block from the current block (the block currently being processed/to be processed) to obtain a residual block, transforming the residual block, and quantizing the residual block in the transform region to reduce the amount of data to be transmitted (compressed). On the decoder side, the encoded or compressed block is back-processed compared to the encoder to reconstruct the current block for presentation. In addition, the encoder duplicates the decoder's processing cycle so that the encoder and decoder generate identical predictions (eg, intra predictions and inter predictions) and/or reconstruction for processing, i.e., encoding subsequent blocks.

The term "block" can be part of an image or frame. Key terms are defined in the present invention as follows:

The current block is the block that is being processed. For example, when encoding, the current block is the block that is currently being encoded; when decoding, the current block is the block that is being decoded. If the block currently being processed is a chrominance component block, the block currently being processed is called the current chroma block. The luma block corresponding to the current chrominance block may be referred to as the current luma block.

CTU is short for coding tree unit. An image includes a plurality of CTUs, and one CTU typically corresponds to one square image area and includes luma samples and chrominance samples in the image area (either may include only luma samples or may include only chrominance samples). The CTU additionally includes syntax elements. These syntax elements indicate how to divide the CTU into at least one coding unit (CU) and decode each coding unit to obtain a reconstructed image.

CU is short for coding unit. The CU typically corresponds to a rectangular region AxB and includes the luminance samples AxB and the chrominance samples corresponding to the luminance samples, where A is the width of the rectangle, B is the height of the rectangle, and A can be the same as or different from B. The values of A and B are typically are integer powers of 2, such as 256, 128, 64, 32, 16, 8, and 4. The encoding block may be decoded by decoding processing to obtain a reconstructed image of the rectangle area AxB. The decoding processing typically includes performing processing such as prediction, dequantization, and inverse transform to generate a predicted image and a residual. The reconstructed image is obtained by overlaying the predicted image and the residual.

Embodiments of encoder 20, decoder 30, and encoding system 10 are described below with reference to FIG. 1A-fig. 3.

Fig. 1A is a conceptual or block diagram illustrating an example of an encoding system 10, such as a video encoding system 10, that may use the techniques of the present invention (of this disclosure). Encoder 20 (eg, video encoder 20) and decoder 30 (eg, video decoder 30) of video coding system 10 represent examples of devices that can be configured to perform intra prediction in accordance with the various examples described in the present invention. As shown in FIG. 1A, the encoding system 10 includes a source device 12 configured to provide encoded data 13, such as an encoded image 13, to a destination device 14 for decoding the encoded data 13.

The source device 12 includes an encoder 20 and may additionally or optionally include an image source 16, a pre-processing unit 18, such as an image pre-processing unit 18, and a communication interface or communication unit 22.

Image source 16 may include or be any type of image capture device, such as for capturing a real image, and/or any type of device for generating an image or comment (for screen content encoding, screen text is also considered part of the image or image to be encoded). ), for example, a computer graphics processor for generating a computer animated image, or any other device for receiving and / or providing an image of the real world, a computer animated image (for example, screen content or a virtual reality image (virtual reality, VR)) and / or any of them combination (for example, an image of augmented reality (augmented reality, AR)).

An image can be thought of as a two-dimensional array or matrix of samples with brightness values. A sample in an array can also be referred to as a pixel (short for picture element) or a pixel. The number of samples in the horizontal and vertical directions (or axes) of an array or image determines the size and/or resolution of the image. To represent a color, three color components are usually used, in particular, an image can be represented as three arrays of samples or can include them. In RBG format or color space, an image includes a corresponding array of red, green, and blue color samples. However, in video encoding, each pixel is typically represented in a luma/chrominance format or color space. For example, YCbCr, which includes a luma component labeled Y (sometimes L is used instead) and two chrominance components labeled Cb and Cr. The Y component of luminance (which is luminance for short) represents the brightness or intensity of the gray level (such as in a grayscale image), while the two chrominance components (which are chroma for short) Cb and Cr represent chrominance or color information components. Accordingly, the YCbCr format image includes a luma sample array of luminance sample values (Y) and two chrominance sample arrays of chroma values (Cb and Cr). Images in RGB format can be converted or converted to YCbCr format and vice versa, and this process is also known as color conversion or conversion. If the image is monochrome, it may only include an array of brightness samples.

Image source 16 (e.g., video source 16) may be, for example, an image capture camera, a memory such as an image memory including or storing a previously captured or generated image, and/or any type (internal or external) interface for receiving an image. The camera may be, for example, a local camera or an integrated camera integrated into the source device, and the memory may be a local memory or an integrated memory, for example, integrated into the source device. The interface may be, for example, an external interface for receiving an image from an external video source. The external video source is, for example, an external image capture device such as a camera, external memory, or an external imaging device. The external imaging device is, for example, an external computer graphics processor, a computer or a server. The interface may be any type of interface, such as a wired or wireless interface, or an optical interface, in accordance with any proprietary or standardized interface protocol. The interface for obtaining image data 17 may be the same interface as the communication interface 22 or may be part of the communication interface 22 .

Unlike the pre-processing unit 18 and the processing performed by the pre-processing unit 18, the image or image data 17 (eg, video data 16) may also be referred to as raw image or original image data 17.

The pre-processing unit 18 is configured to: receive (raw) image data 17 and pre-processed image data 17 to obtain a pre-processed image 19 or pre-processed image data 19. For example, the pre-processing performed by the pre-processor 18 may include cropping, color format conversion (eg, conversion from RGB to YCbCr), color adjustment, and noise reduction. Obviously, the pre-processing unit 18 could be a possible component.

The encoder 20 (eg, video encoder 20) is configured to receive pre-processed image data 19 and provide encoded image data 21 (details are further described below, for example, with reference to FIG. 2 or FIG. 4). In one example, encoder 20 may be configured to implement embodiments 1-3.

The communication interface 22 of source device 12 may be configured to: receive encoded image data 21 and transmit encoded image data 21 to another device, such as destination device 14 or any other device, for storage or direct retrieval, or may be configured to process data 21 encoded image before appropriately storing the encoded data 13 and/or transmitting the encoded data 13 to another device, where the other device is, for example, the destination device 14 or any other device. for decoding or storage.

Destination device 14 includes a decoder 30 (eg, video decoder 30) and may additionally, that is, possibly, include a communication interface or communication unit 28, a post-processing unit 32, and a display device 34.

The communication interface 28 of the destination device 14 is configured to receive encoded image data 21 or encoded data 13, for example directly from source device 12 or from any other source. Any other source is, for example, a storage device such as an encoded image data storage device.

Communication interface 22 and communication interface 28 may be configured to transmit or receive encoded image data 21 or encoded data 13 over a direct link between source device 12 and destination device 14 or over any type of network. A direct link is, for example, a direct wired or wireless connection, and any type of network is, for example, a wired or wireless network, or any combination thereof, or any type of private and public networks, or any combination thereof.

The communication interface 22 may, for example, be configured to package the encoded image data 21 into an appropriate format, such as packets, for transmission over a communication channel or communication network.

The communication interface 28, analogous to the communication interface 22, may be configured to decompress the encoded data 13 to obtain encoded image data 21, for example.

Both communication interface 22 and communication interface 28 can be configured as unidirectional communication interfaces as indicated by the arrow for encoded data 13 from source device 12 to destination device 14 in FIG. 1A, or may be configured as a bi-directional communication interface and may be configured to, for example, send and receive messages to establish a connection, as well as acknowledge and exchange any other information related to the communication channel and/or data transmission, such as the transmission of encoded data. Images.

The decoder 30 is configured to receive encoded image data 21 and provide decoded image data 31 or decoded image 31 (details are further described below, for example, with reference to FIG. 3 or FIG. 5). In one example, decoder 30 may be configured to implement embodiments 1-3.

The post processor 32 of the destination device 14 is configured to post-process the decoded image data 31 (also referred to as reconstructed image data), such as the decoded image 131, to obtain an image after processing the data 33, such as the post-processed image 33. Post-processing performed by the post-processing unit 32 , may include, for example, color format conversion (eg, conversion from YCbCr to RGB), color correction, cropping or resampling, or any other processing, for example, to prepare the decoded image data 31 for display by the display device 34.

The display device 34 of the destination device 14 is configured to receive the image data 33 after processing, to display the image to a user, viewer, or the like. The display device 34 may be or include any type of display for presenting the reconstructed image, such as an integrated or external display or monitor. For example, the display may include a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a plasma display, a projector, a micro LED display, a liquid crystal on silicon , LCoS), digital light processor (DLP) or any other display.

Although FIG. 1A depicts source device 12 and destination device 14 as separate devices, an embodiment of the device may alternatively include both source device 12 and destination device 14, or the functionality of both source device 12 and destination device 14, i.e., device 12 source or corresponding function and device 14 destination or corresponding function. In such an embodiment, source device 12 or related functionality and destination device 14 or related functionality may be implemented using the same hardware and/or software, separate hardware and/or software, or any combination thereof.

As will be apparent to one skilled in the art based on the descriptions, the (precise) separation of the functionality of the various blocks or functions of source device 12 and/or destination device 14 shown in FIG. 1A may differ depending on the actual device and application.

Encoder 20 (e.g., video encoder 20) and decoder 30 (e.g., video decoder 30) may be implemented as any of various suitable circuits, e.g., one or more microprocessors, digital signal processor (DSP), application specific integrated circuit (application -specific integrated circuit (ASIC), field-programmable gate array (FPGA), discrete logic, hardware, or any combination thereof. If the technologies are implemented in part using software, the device may store the program instruction on an appropriate permanent computer-readable storage medium and may execute the instruction using hardware, such as one or more processors, to implement the technologies of the present invention. Any of the above content (including hardware, software, a combination of hardware and software, and the like) may be considered one or more processors. Video encoder 20 and video decoder 30 may each be contained in one or more encoders or decoders, and either the encoder or decoder may be integrated into a combined encoder/decoder (codec) portion of a respective device.

The source device 12 may be referred to as a video encoding device or a video encoding tool. The destination device 14 may be referred to as a video decoding device or a video decoding tool. Source device 12 and destination device 14 may be examples of a video encoding device or a video encoding device.

Source device 12 and destination device 14 may include any of a wide range of devices, including any type of portable or stationary device, such as a laptop or laptop computer, mobile phone, smartphone, tablet or tablet computer, camera, desktop computer, set-top box. , a television, a display device, a digital media player, a game console, a video streaming device (such as a content service server or a content delivery server), a broadcast receiver device, or a broadcast transmitter device, and may or may not use any type of operating system.

In some cases, source device 12 and destination device 14 may be equipped for wireless communication. Therefore, source device 12 and destination device 14 may be wireless communication devices.

In some cases, the video coding system 10 shown in FIG. 1A is just an example, and the techniques of the present invention are applicable to video encoding settings (eg, video encoding or video decoding) that do not necessarily include any communication between encoding and decoding devices. In another example, data may be retrieved from local memory, streamed over a network, or the like. The video encoding device may encode the data and store the data in memory, and/or the video decoding device may retrieve the data from the memory and decode the data. In some examples, encoding and decoding are performed by devices that do not communicate with each other, but simply encode data into memory and/or retrieve data from memory and decode the data.

It should be understood that for each of the above examples described with reference to video encoder 20, video decoder 30 may be configured to reverse the process. With regard to signaling syntax elements, video decoder 30 may be configured to receive and parse these syntax elements and decode the corresponding video data. In some examples, video encoder 20 may entropy encode syntax elements into an encoded video bitstream. In these examples, video decoder 30 may parse these syntax elements and decode the corresponding video data accordingly.

Fig. B is an illustrative diagram of an example video coding system 40 including encoder 20 in FIG. 2 and/or decoder 30 in FIG. 3 according to an exemplary embodiment. System 40 may implement a combination of various technologies of the present invention. In the illustrated implementation, the video encoding system 40 may include an imager 41, a video encoder 20, a video decoder 30 (and/or a video encoder/decoder implemented by processing unit 46 logic 47), an antenna 42, one or more processors 43, one or more memories 44 and/or display device 45.

As shown in the drawing, the imaging device 41, the antenna 42, the processing unit 46, the logic circuit 47, the video encoder 20, the video decoder 30, the processor 43, the memory 44 and/or the display device 45 may interact with each other. As described, although video encoding system 40 is illustrated using video encoder 20 and video decoder 30, in another example, video encoding system 40 may include only video encoder 20 or only video decoder 30.

In some examples, as shown in the drawing, video coding system 40 may include an antenna 42. For example, antenna 42 may be configured to transmit or receive encoded bitstream video data. In addition, in some examples, the video coding system 40 may include a display device 45 . The display device 45 may be configured to present video data. In some examples, as shown in the drawing, the logic circuit 47 may be implemented by the block 46 processing. The processing unit 46 may include application-specific integrated circuit (ASIC) logic, a graphics processor, a general purpose processor, and the like. The video encoding system 40 may also include an additional processor 43. The additional processor 43 may likewise include application-specific integrated circuit (ASIC) logic, a graphics processor, a general purpose processor, and the like. In some examples, logic circuitry 47 may be implemented in hardware, such as dedicated video coding hardware, and processor 43 may be implemented in general purpose software, an operating system, or the like. Additionally, the memory 44 may be any type of memory, such as volatile memory (for example, Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM) or non-volatile memory (for example, In a non-limiting example, memory 44 may be implemented using cache memory. In some examples, logic circuit 47 may access memory 44 (for example, to implement an image buffer). In other examples, logic circuit 47 and/or block 46 processing may include memory (eg, cache) for implementing an image buffer, and the like.

In some examples, the video encoder 20 implemented by the logic circuit may include an image buffer (which, for example, is implemented by processing unit 46 or memory 44) and a graphics processing unit (which, for example, is implemented by processing unit 46). The graphics processing unit may be communicatively connected to the image buffer. The graphics processing unit may include a video encoder 20 implemented by logic 47 to implement the various modules that are described with reference to FIG. 2 and/or any other encoder system or subsystem described in this specification. The logic circuit may be configured to perform various operations described in this specification.

Video decoder 30 may be implemented in a manner similar to that implemented by logic circuitry 47 to implement various modules as described with respect to decoder 30 in FIG. 3 and/or any other decoder system or subsystem described in this specification. In some examples, video decoder 30 implemented by logic may include an image buffer (which, for example, is implemented by processing unit 2820 or memory 44) and a graphics processing unit (which, for example, is implemented by processing unit 46). The graphics processing unit may be communicatively connected to the image buffer. The graphics processing unit may include a video decoder 30 implemented by logic 47 to implement various modules, which are described with reference to FIG. 3 and/or any other decoder system or subsystem described in this specification.

In some examples, antenna 42 of video coding system 40 may be configured to receive video data of the encoded bitstream. As described, the encoded bitstream may include data, an indicator, an index value, mode selection data, and the like, which is related to the encoding of video frames and which is described in this specification, for example, data related to coding separation (for example, coefficient transform or a quantized transform coefficient, an optional indicator (as described) and/or data defining a coding split). The video coding system 40 may further include a video decoder 30 that is connected to the antenna 42 and configured to decode the encoded bit stream. The display device 45 is configured to present a video frame.

Encoder & encoding method

Fig. 2 is a schematic/conceptual block diagram of an example of a video encoder 20 capable of implementing the technology (disclosed) in the present invention. In the example in FIG. 2, the video encoder 20 includes a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a buffer 216, a loop filter unit 220, a decoded image buffer 230 (decoded picture buffer, DPB), prediction processing unit 260, and entropy encoding unit 270. The prediction processing block 260 may include an inter prediction block 244, an intra prediction block 254, and a mode selection block 262. Inter prediction block 244 may include a motion estimator and a motion compensation block (which is not shown in the diagram). Video encoder 20 shown in FIG. 2 may also be referred to as a hybrid video encoder or a video encoder based on a hybrid video codec.

For example, the residual calculation block 204, the transform processing block 206, the quantization block 208, the prediction processing block 260, and the entropy encoding block 270 form a direct signal path of the encoder 20, while, for example, the inverse quantization block 210, the inverse transform processing block 212, block 214 recovery buffer 216, loop filter 220, decoded picture buffer (DPB) 230, and prediction processor 260 form an encoder return signal path, where the video encoder return signal path corresponds to the decoder signal path (see decoder 30 in FIG. 3) .

Encoder 20 receives, for example, via input 202 an image 201 or a block 203 of image 201, for example an image in a sequence of images constituting a video or video sequence. Image block 203 may also be referred to as the current image block or image block to be encoded, and image 201 may be referred to as the current image or image to be encoded (particularly in video encoding, to distinguish the current image from other images, e.g. , previously encoded and/or decoded pictures in the same video sequence, namely a video sequence that also includes the current picture).

Separation

In an embodiment, encoder 20 may include a splitter (which is not shown in FIG. 2) configured to split image 201 into multiple blocks, such as blocks 203. Image 201 is typically divided into multiple non-overlapping blocks. The dividing block may be configured to: use the same block size for all images of the video sequence and the corresponding grid defining the block size, or change the block size between images or subsets or groups of images and divide each image into appropriate blocks.

In one example, prediction processing unit 260 of video encoder 20 may be configured to perform any combination of the aforementioned separation techniques.

Like image 201, block 203 is also or can be thought of as a two-dimensional array or matrix of samples with sample values, although the size of block 203 is smaller than the size of image 201. In other words, block 203 may include, for example, one array of samples ( eg, a luminance array in the case of a monochrome image 201), three sample arrays (eg, one luminance array and two chrominance arrays in the case of a color image), or any other number and/or type of arrays depending on the color format used. The number of samples in the horizontal and vertical directions (or axes) of block 203 determines the size of block 203.

Encoder 20 shown in FIG. 2 is configured to encode image 201 block by block, such as encoding and predicting each block 203.

Remainder Calculation

Residual block 204 is configured to calculate residual block 205 based on image block 203 and predictor 265 (details on predictor 265 are further provided below), for example, by subtracting sample values of predictor 265 from sample values of image block 203 sample by sample ( pixel by pixel) to obtain a residual block 205 in the sample area.

transformation

The transform processing unit 206 is configured to apply transforms, such as a discrete cosine transform (DCT) or a discrete sine transform (DST), to the sample values of the residual block 205 to obtain transform coefficients 207 in the transform domain. The transform coefficients 207 may also be referred to as residual transform coefficients and represent the residual block 205 in the transform region.

Transform processing unit 206 may be configured to apply DCT/DST integer approximations such as the transforms specified in HEVC/H.265. Compared to the orthogonal DCT, such integer approximations are usually scaled by a certain factor. To preserve the norm of the residual block that is processed using forward and inverse transforms, an additional scaling factor is applied as part of the transform process. The scaling factor is usually chosen based on some constraints, for example, the scaling factor is a power of two for the shift operation, the bit depth of the transform coefficients, and a trade-off between accuracy and implementation cost. For example, a specific scaling factor is set for the inverse transform, for example, by the inverse transform processing unit 212 on the decoder 30 side (and the corresponding inverse transform, for example, by the inverse transform processing unit 212 on the encoder 20 side), and accordingly, the corresponding scaling factor can be specified for direct conversion by the conversion processing unit 206 on the side of the encoder 20.

Quantization

Quantizer 208 is configured to quantize transform coefficients 207 to obtain quantized transform coefficients 209, for example by applying scalar quantization or vector quantization. The quantized transform coefficients 209 may also be referred to as quantized residual coefficients 209. The quantization process may reduce the bit depth associated with some or all of the transform coefficients 207. For example, an n-bit transform factor may be rounded to an m-bit transform factor during quantization, where n is greater than m. The degree of quantization can be changed by adjusting the quantization parameter (QP). For example, for scalar quantization, different scaling may be applied to achieve finer or coarser quantization. Smaller quantization step size corresponds to finer quantization and larger quantization step size corresponds to coarser quantization. The appropriate quantization step size may be indicated by a quantization parameter (QP). For example, the quantization parameter may be an index to a given set of suitable quantization step sizes. For example, a smaller quantization parameter may correspond to finer quantization (smaller quantization step size) and a larger quantization parameter may correspond to coarser quantization (larger quantization step size) or vice versa. Quantization may include dividing by the quantization step size and corresponding quantization or inverse quantization, such as performed by inverse quantizer 210, or may include multiplying by the quantization step size. Embodiments according to some standards, such as HEVC, may use a quantization parameter to determine the quantization step size. Typically, the quantization step size can be calculated based on the quantization parameter using a fixed-point approximation of an equation involving division. Additional scaling factors for quantization and dequantization can be introduced to restore the residual block norm, which can be changed due to the scaling used in the fixed-point approximation of the equation for the quantization step size and the quantization parameter. In one exemplary implementation, inverse transform scaling and dequantization may be combined. Alternatively, customized quantization tables can be used and transmitted from the encoder to the decoder, for example, in a bit stream. Quantization is a lossy operation in which the loss increases as the quantization step size increases.

The inverse quantizer 210 is configured to apply the inverse quantization of the quantizer 208 to the quantized coefficients to obtain the dequantized coefficients 211, for example, apply, based on or using the same quantization step size as the quantizer 208, the inverse quantization scheme applied by the quantizer 208 quantization. The dequantized coefficients 211 may also be referred to as the dequantized residual coefficients 211 and correspond to the transform coefficients 207, although they are usually not identical to the transform coefficients due to losses caused by quantization.

The inverse transform processing unit 212 is configured to apply the inverse transform applied by the transform processing unit 206, such as an inverse discrete cosine transform (DCT) or an inverse discrete sine transform (DST), to obtain an inverse transform unit 213 in the sample area. The inverse transform block 213 may also be referred to as the dequantized inverse transform block 213 or the residual inverse transform block 213 .

Restoration block 214 (e.g., adder 214) is configured to add inverse transform block 213 (i.e., restored residual block 213) to prediction block 265, for example, by adding the sample values of the restored residual block 213 and the sample value of prediction block 265 to obtain reconstructed block 215 in the sample area.

Optionally, buffer block 216 (or "buffer" 216 for short), such as linear buffer 216, is configured to buffer or store the reconstructed block 215 and the corresponding sample value, such as for intra prediction. In other embodiments, the encoder may be configured to use the unfiltered reconstructed block and/or the corresponding sample value stored in buffer block 216 for any type of estimation and/or prediction, such as intra prediction.

For example, in an embodiment, encoder 20 may be configured for buffer block 216 to not only store reconstructed block 215 for intra prediction 254, but is also used for loop filter block 220 (which is not shown in FIG. 2), and/or so, that, for example, buffer block 216 and decoded picture buffer block 230 form one buffer. In other embodiments, filtered blocks 221 and/or blocks or samples from decoded picture buffer 230 (blocks or samples not shown in FIG. 2) are used as input or basis for intra prediction 254.

The loop filter block 220 (or "loop filter" 220 for short) is configured to filter the reconstructed block 215 to obtain a filtered block 221, smooth pixel transitions, or improve video quality. The loop filter block 220 is designed to represent one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or another filter, such as a two-sided filter, an adaptive loop filter, ALF), sharpen or smooth filter, or collective filter. Although the loop filter unit 220 is shown in FIG. 2, in another configuration, the loop filter block 220 may be implemented as a post-loop filter. The filtered block 221 may also be referred to as the filtered reconstructed block 221. The decoded picture buffer 230 may store the reconstructed coded blocks after the loop filter block 220 performs filtering operations on the reconstructed coded blocks.

In an embodiment, encoder 20 (respectively, loop filter block 220) may be configured to output loop filter parameters (such as adaptive bias sample information), for example, directly or after entropy encoding performed by entropy encoding block 270 or any other entropy encoding block. so that, for example, decoder 30 can receive the same loop filter parameters and apply the same loop filter parameters for decoding.

Decoded picture buffer (DPB) 230 may be a reference picture memory that stores reference picture data for use in encoding video data by video encoder 20. DPB 230 may be formed by any of a variety of memory devices, such as dynamic random access memory ( dynamic random access memory, DRAM) (including synchronous DRAM (synchronous DRAM, SDRAM), magnetoresistive RAM (magneto resistive RAM, MRAM), resistive RAM (resistive RAM, RRAM)) or other types of storage devices. DPB 230 and buffer 216 may be provided by the same memory or separate storage devices. In an example, decoded picture buffer (DPB) 230 is configured to store a filtered block 221. Decoded picture buffer 230 may be further configured to store other previously filtered blocks, such as previously reconstructed and filtered blocks 221 of the same of the current picture or different pictures, e.g., previously reconstructed pictures, and may provide completely previously reconstructed pictures, i.e., decoded pictures (and corresponding reference blocks and samples) and/or partially reconstructed current picture (and corresponding reference blocks and samples), e.g. , for external prediction. In one example, if the reconstructed block 215 is reconstructed without in-loop filtering, the decoded picture buffer (DPB) 230 is configured to store the reconstructed block 215.

The prediction processing unit 260, also referred to as the block prediction processing unit 260, is configured to receive or obtain an image block 203 (the current block 203 of the current image 201) and reconstructed image data such as a reference sample of the same (current) image from the buffer 216 and/or reference picture data 231 from one or more previously decoded pictures from decoded picture buffer 230 and process that data for prediction, to be specific, to provide prediction block 265, which may be inter prediction block 245 or intra prediction block 255.

Mode selector 262 may be configured to select a prediction mode (e.g., intra or inter prediction mode) and/or a corresponding prediction block 245 or 255 to be used as prediction block 265 to compute the residual block 205 and to recover the reconstructed block. 215.

In an embodiment, mode selector 262 may be configured to select a prediction mode (eg, from among the prediction modes supported by prediction processor 260). The predictive mode provides the best match, or in other words, minimum residual (lowest residual means better compression for transmission or storage), or provides minimum signaling overhead (minimum signaling overhead means better compression for transmission or storage), or takes into account or balances both. The mode selector 262 may be configured to determine a prediction mode based on rate distortion optimization (RDO), i.e., select a prediction mode that provides the minimum rate distortion optimization, or select a prediction mode for which the corresponding rate the distortion at least satisfies the prediction mode selection criterion.

Further, a detailed description is given of the prediction processing performed (for example, using the prediction processing block 260) and the mode selection performed (for example, using the mode selection block 262) using the example encoder 20.

As described above, encoder 20 is configured to determine or select the best prediction mode or optimal prediction mode from a set of (predetermined) prediction modes. The set of prediction modes may include, for example, intra prediction modes and/or inter prediction modes.

The set of intra prediction modes may include 35 different intra prediction modes, or may include 67 different intra prediction modes, or may include a developing intra prediction mode defined in H.266.

The plurality of interrelated prediction modes depends on the available reference frame (i.e., at least a portion of the decoded picture stored in DBP 230) and another inter-prediction parameter, such as whether all reference pictures or only part of the reference picture are used, for example, an area search box around the area of the current block, to find the best match of the reference block and/or depending on, for example, whether pixel interpolation is applied, such as half-pixel and/or quarter-pixel interpolation.

In addition to the aforementioned prediction modes, a skip mode and/or a direct mode may be applied.

The prediction processor 260 may be further configured to partition the block 203 into smaller block sections or sub-blocks, for example, by iteratively using quad-tree (QT) partitioning, binary-tree (BT), ternary partitioning. tree (triple-tree, TT) or any combination of them, as well as to perform, for example, prediction for each of the sections of blocks or subblocks. Mode selection includes selecting a tree structure of the partitioned block 203 and selecting a prediction mode applied to each of the block partitions or subblocks.

Inter prediction block 244 may include a motion estimation (ME) block (which is not shown in FIG. 2) and a motion compensation (MC) block (which is not shown in FIG. 2). The motion estimator is configured to receive or obtain a picture block 203 (the current picture block 203 of the current picture 201) and a decoded picture 231 of at least one or more previously reconstructed blocks, e.g., one or more reconstructed blocks of other/different previously decoded 231 images for motion estimation. For example, the video sequence may include the current picture and previously decoded pictures 31. In other words, the current picture and previously decoded pictures 31 may be part of or form a sequence of pictures that make up the video sequence.

Thus, for example, encoder 20 may be configured to select a reference block from a plurality of reference blocks of the same picture or different pictures from a plurality of other pictures, and supply to a motion estimator (which is not shown in FIG. 2) a reference picture and/or an offset (spatial offset) between the position (X and Y coordinates) of the reference block and the position of the current block as an inter prediction parameter. This offset is also called the motion vector (MV).

The motion compensation block is configured to receive, for example, receive inter prediction parameters, and perform inter prediction based on or using the inter prediction parameters to obtain inter prediction block 245 . Motion compensation performed by a motion compensator (which is not shown in FIG. 2) may include sampling or generating a prediction block based on a motion vector/block determined by motion estimation (perhaps by performing sub-pixel interpolation). Interpolation filtering can generate additional pixel samples from known pixel samples, thereby potentially increasing the number of prediction block candidates that can be used to encode an image block. After receiving the motion vector for the PU of the current picture block, the motion compensator 246 may find the prediction block pointed to by the motion vector in one of the reference picture lists. Motion compensation block 246 may also generate syntax elements associated with video blocks and segments for use by video decoder 30 when decoding image blocks of a video segment.

The intra prediction block 254 is configured to receive, for example, an image block 203 (of the current image block) and one or more previously reconstructed blocks, such as reconstructed adjacent blocks, of the same image for intra estimation. Encoder 20 may be, for example, configured to select an intra prediction mode from a plurality of (predetermined) intra prediction modes.

In an embodiment, encoder 20 may be configured to select an intra prediction mode based on an optimization criterion, such as minimum residual (e.g., intra prediction mode providing a prediction block 255 that best fits the current image block 203) or minimum rate distortion. .

The intra prediction block 254 is further configured to determine the intra prediction block 255 based on, for example, intra prediction parameters in the selected intra prediction mode. In any case, after the block intra prediction mode is selected, the intra prediction block 254 is further configured to provide intra prediction parameters, that is, information indicative of the selected block intra prediction mode, to the entropy encoding block 270 . For example, intra predictor 254 may be configured to perform any combination of intra prediction technologies described below.

The entropy encoding unit 270 is configured to apply (or not apply) an entropy coding algorithm or schemes (e.g., variable length coding (VLC) scheme, context adaptive VLC (context adaptive VLC, CAVLC), arithmetic coding scheme , context-adaptive binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy , PIPE) or other entropy coding method or technology) to one or all of the quantized residual coefficients 209, inter prediction parameters, intra prediction parameters, and/or loop filter parameters to obtain encoded image data 21 that can be output via output 272, e.g. ep, in the form of an encoded bitstream 21. The encoded bitstream may be transmitted to video decoder 30, or stored for later transmission or retrieval by video decoder 30. Entropy encoding unit 270 may be further configured to entropy encode other syntax elements for the current video segment being encoded.

Other structural variations of video encoder 20 may be used to encode the video stream. For example, for some blocks or frames, non-transform-based encoder 20 may quantize the residual signal directly without transform processing block 206 . In another implementation, the encoder 20 may have a quantizer 208 and an inverse quantizer 210 combined into a single block.

Fig. 3 shows an example of a video decoder 30 capable of implementing the technology of the present invention. Video decoder 30 is configured to receive encoded picture data (eg, encoded bitstream) encoded by, for example, encoder 20 to obtain a decoded image 231. In the decoding process, video decoder 30 receives video data from video encoder 20, such as an encoded video bitstream that represents an image block of an encoded video segment and associated syntax elements.

In the example in FIG. 3, the decoder 30 includes an entropy decoding block 304, an inverse quantization block 310, an inverse transform processing block 312, a reconstruction block 314 (e.g., adder 314), a buffer 316, a loop filter 320, a decoded image buffer 330, and a prediction processing block 360. The prediction processing block 360 may include an inter prediction block 344, an intra prediction block 354, and a mode selection block 362. In some examples, video decoder 30 may perform a decoding process that is generally the reverse of the encoding process described with reference to video encoder 20 in FIG. 2.

The entropy decoding unit 304 is configured to perform entropy decoding of the encoded image data 21 to obtain, for example, quantized coefficients 309 and/or decoded coding parameters (which are not shown in FIG. 3), for example, any one or all of the inter prediction parameters, intra predictions, loop filter parameters, and/or other syntax elements (which are decoded). Entropy decoding block 304 is further configured to send inter prediction parameters, intra prediction parameters, and/or other syntax elements to prediction processing block 360 . Video decoder 30 may receive syntax elements at the video segment level and/or video block level.

The inverse quantization block 310 may have the same function as the inverse quantization block 110, the inverse transform processing block 312 may have the same function as the inverse transform processing block 212, the reconstruction block 314 may have the same function as the reconstruction block 214 , buffer 316 may have the same function as buffer 216, loop filter 320 may have the same function as loop filter 220, and decoded picture buffer 330 may have the same function as decoded picture buffer 230.

Prediction processing block 360 may include an inter prediction block 344 and an intra prediction block 354 . Inter prediction block 344 may be similar to inter function prediction block 244 and intra prediction block 354 may be similar to intra function prediction block 254 . Prediction processing unit 360 is typically configured to perform block predictions and/or obtain prediction block 365 from encoded data 21, and to receive or obtain (explicitly or implicitly) prediction-related parameters and/or information about the selected prediction mode, for example, from block 304 entropy decoding.

When a video segment is encoded as an intra (I) segment, the intra prediction block 354 of the prediction processing block 360 is configured to generate a prediction block 365 for a picture block of the current video segment based on the signaled intra prediction mode and data from previously decoded blocks of the current frame or picture. . When a video frame is encoded as an inter-coded (i.e., B or P) segment, the inter prediction block 344 (e.g., motion compensation block) of the prediction processing block 360 is configured to generate a predictor 365 for the video block of the current video segment based on the motion vector and other elements. syntax received from block 304 entropy decoding. For inter prediction, a prediction block may be generated from one of the reference pictures in one of the reference picture lists. Video decoder 30 may construct reference frame lists, list 0 and list 1 using default construction techniques based on reference pictures stored in DPB 330.

The prediction processing unit 360 is configured to determine prediction information for a video block of the current video segment by parsing the motion vector and other syntax elements and using the prediction information to generate a prediction block for the current decoded video block. For example, prediction processing block 360 uses some of the received syntax elements to determine the prediction mode (eg, intra or inter prediction) used to encode video blocks of a video segment, the type of inter prediction segment (eg, B-segment, P-segment, or GPB-segment ), structure information of one or more reference picture lists for a segment, motion vectors for each inter-coded video block of the segment, inter-prediction status for each inter-coded video block of the segment, and other information for decoding video blocks in the current segment.

Inverse quantizer 310 may be configured to inverse quantize (ie, dequantize) the quantized transform coefficients provided in the bitstream and decoded by entropy decoder 304 . The inverse quantization process may include: using the quantization parameters calculated by video encoder 20 for each video block in a video segment to determine the amount of quantization to be applied, and likewise the amount of inverse quantization to be applied.

The inverse transform processing unit 312 is configured to apply an inverse transform (eg, inverse DCT, inverse integer transform, or a conceptually similar inverse transform process) to transform the coefficients to generate a residual block in the pixel region.

A restorer 314 (eg, adder 314) is configured to add an inverse transform block 313 (namely, a reconstructed residual block 313) to a prediction block 365, for example, by adding sample values of the reconstructed residual block 313 and a sample value of prediction block 365 to obtain reconstructed block 315 in the sample area.

The loop filter block 320 (either in the encoding loop or after the encoding loop) is configured to filter the reconstructed block 315 to obtain a filtered block 321, smooth pixel transitions, or improve video quality. In one example, the loop filter unit 320 may be configured to perform any combination of the filter technologies described below. The loop filter block 320 is designed to represent one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or another filter, such as a two-sided filter, an adaptive loop filter, ALF), sharpen or smooth filter, or collective filter. Although the loop filter unit 320 is shown in FIG. 3, in another configuration, the loop filter block 320 may be implemented as a post-loop filter.

The decoded video blocks 321 in that frame or picture are then stored in the decoded picture buffer 330, which stores reference pictures used for subsequent motion compensation.

The decoder 30 is configured to, for example, output the decoded image 31 via output 332 for presentation to or viewing by the user.

Other variants of video decoder 30 may be configured to decode the compressed bitstream. For example, decoder 30 may generate an output video stream without loop filter block 320 . For example, the non-transform decoder 30 may inversely quantize the residual signal directly without the inverse transform processor 312 for some blocks or frames. In another implementation, video decoder 30 may have an inverse quantizer 310 and an inverse transform processor 312 combined into one unit.

Fig. 4 is a schematic block diagram of a video encoding device 400 (eg, video encoding device 400 or video decoding device 400) according to an embodiment of the present invention. The video encoder 400 is suitable for implementing the embodiments described in this specification. In an embodiment, video encoding device 400 may be a video decoder (eg, video decoder 30 in FIG. 1A) or a video encoder (eg, video encoder 20 in FIG. 1A).). In another embodiment, video encoding device 400 may be one or more components in video decoder 30 in FIG. 1A or video encoder 20 in FIG. 1A.

The video encoder 400 includes input ports 410 and a receiver (Rx) unit 420 that are designed to receive data; a processor, logical unit, or central processing unit (CPU) 430 for processing data; a transmitter (Tx) unit 440 and output ports 450 that are dedicated to transmitting data; and a memory 460 for storing data. The video encoder 400 may also include optical-electrical components and electrical-optical (EO) components that are connected to input ports 410, receiver unit 420, transmitter unit 440, and output ports 450 for outputting or inputting optical or electrical signals.

Processor 430 is implemented in hardware and software. Processor 430 may be implemented as one or more CPU chips, cores (eg, a multi-core processor), FPGA, ASIC, and DSP. Processor 430 communicates with input ports 410, receiver unit 420, transmitter unit 440, output ports 450, and memory 460. Processor 430 includes an encoding module 470 (eg, encoding module 470 or decoding module 470). The encoding/decoding module 470 implements the above disclosed embodiments. For example, the encoding/decoding module 470 performs, processes, or provides various encoding operations. Therefore, the encoding/decoding module 470 provides a significant improvement in the functionality of the video encoding device 400 and affects the conversion of the video encoding device 400 to another state. Alternatively, encode/decode module 470 is implemented as instructions stored in memory 460 and executed by processor 430.

Memory 460 includes one or more disks, tape drives, and solid state drives and can be used as a storage device for overflowing data, for storing programs when those programs are selected for execution, and for storing instructions and data that are read during program execution. . Memory 460 may be volatile and/or non-volatile and may be read only memory (ROM), random access memory (RAM), ternary content-addressable memory (TCAM), and/or static random access memory (SRAM). ).

Fig. 5 is a simplified block diagram of a device 500 that can be used as one or two of source device 12 and destination device 14 in FIG. 1A according to an exemplary embodiment. Device 500 may implement the technology of the present invention. The device 500 for realizing image division may be in the form of a computing system including a plurality of computing devices, or in the form of a single computing device such as a mobile phone, tablet computer, laptop computer, or desktop computer.

Processor 502 of device 500 may be a central processing unit. Alternatively, processor 502 may be any other type of device or a plurality of devices that can control or process information that are currently in use or will be developed in the future. As shown in the drawing, although the disclosed implementations may be implemented with a single processor, such as processor 502, speed and efficiency advantages may be achieved by using more than one processor.

In an implementation, the memory 504 of the device 500 may be Read Only Memory (ROM) or random access memory (RAM). The memory 504 may be any other suitable type of storage device. Memory 504 may include code and data 506 accessed by processor 502 using bus 512. Memory 504 may further include operating system 508 and application programs. 510. Application programs 510 include at least one program that allows the processor 502 to perform the methods described in this specification. For example, applications 510 may include applications 1 through N, applications 1 through N further include a video encoding application that performs the method described in this specification. Device 500 may also include additional memory in the form of secondary storage 514. Secondary storage 514 may be, for example, a memory card used with a mobile computing device. Because video communications may contain a large amount of information, this information may be stored in whole or in part in secondary storage 514 and loaded into memory 504 as needed for processing.

The device 500 may also include one or more output devices, such as a display 518. In an example, the display 518 may be a touch display that combines a display with a touch element that is configured to accept touch inputs. Display 518 may be coupled to processor 502 via bus 512. In addition to or alternatively to display 518, other output devices may be provided that allow a user to program or otherwise use device 500. When an output device is or includes a display, The display can be implemented in a variety of ways, including liquid crystal display (LCD), cathode-ray tube (CRT), plasma display, or light emitting diode (LED) display , a display such as an organic LED (organic LED, OLED) display.

The device 500 may also include or be connected to an imaging device 520. The imaging device 520 is, for example, a camera or any other imaging device 520 capable of sensing an image that is currently in use or will be developed in the future. The image is, for example, an image of a user who uses the device 500. The image reader 520 may be placed directly in front of the user who starts the device 500. In the example, the position and optical axis of the image reader 520 may be configured such that the field of view of the device 520 imaging includes an area adjacent to the display 518, and the display 518 can be seen from this area.

The device 500 may also include or interact with an audio detection device 522, such as a microphone or any other audio device that is currently in use or will be developed in the future that can sense sounds in the vicinity of the device 500. The audio detection device 522 may be placed directly in front of the user who starts the device 500, and may be configured to receive sound, such as a voice or other sound made by the user when the device 500 is started.

Although FIG. 5 depicts the processor 502 and memory 504 of the device 500 as being integrated into a single unit, other configurations may be used. The operation of the processor 502 may be distributed among a plurality of machines (each machine includes one or more processors), which may be directly connected or distributed over a local area or other network. Memory 504 may be distributed across multiple machines, such as network storage or memory across multiple machines running device 500. Although depicted here as a single bus, bus 512 of device 500 may include multiple buses. Additionally, secondary storage 514 may be directly connected to other components of the device 500 or may be accessed over a network and may include a single integrated unit, such as a memory card, or multiple units, such as a plurality of memory cards. Thus, device 500 can be implemented in a wide variety of configurations.

As described above in the present invention, in addition to using a luminance (Y) component, color video further includes chrominance (U, V) components. Therefore, in addition to encoding the luminance component, it is also necessary to encode the chrominance components. According to different sampling methods of luma component and chrominance components, YUV4:4:4, YUV4:2:2, and YUV4:2:0 are commonly used in color video. As shown in FIG. 6, a cross represents a luma component sample and a circle represents a chrominance component sample.

The 4:4:4 format indicates that the chrominance component is not downsampled.

The 4:2:2 format indicates that 2:1 horizontal downsampling is performed on the luminance component of the chroma component and no vertical downsampling is performed on the chrominance component. For every two U or V samples, each row includes four Y samples.

The 4:2:0 format indicates that the luminance component is downsampled 2:1 horizontally and the chrominance component is vertically downsampled 2:1.

The video decoder may be configured to partition a video block according to three different partition patterns (QT, BT, and TT) using five different partition types allowed at each depth. Split types include quadtree split structure (QT split structure), horizontal binary tree split (BT split structure), vertical binary tree split (BT split structure), and horizontal ternary tree split in the center (TT split structure), and vertical ternary split tree in the center (TT split structure), as shown in Fig. 7A-fig. 7E.

The five types of division are defined as follows: it should be noted that a square is considered as a special case of a rectangle.

Quad-tree splitting (QT): The block is further divided into four rectangular blocks of the same size. Fig. 7A shows an example of splitting a quadtree. According to the QT quadtree-based CTU partitioning method, the CTU is used as the root node of the quadtree. The CTU is recursively split into multiple leaf nodes based on the split mode of the quadtree. One node corresponds to one area of the image. If a node is not split, the node is called a leaf node, and the image area corresponding to the node becomes CU. If the node is split, the image area corresponding to the node is divided into four image areas of the same size (the length and width of the four areas are respectively half the length and width of the split area), and each area corresponds to one node. It is separately determined whether these nodes will be further divided. Whether a node should be split is indicated by the split_cu_flag flag, which is in the bitstream and corresponds to the node. The depth (qtDepth) of the root node's quadtree is 0, and the depth of the child node's quadtree is the parent node's quadtree depth plus 1. For brevity, the size and shape of the node in the present invention is the size and shape of the image area corresponding to the node, that is, the node is rectangular area in the image. A node obtained by splitting a node in an encoding tree may be called a child node of a node, which is a child node for short.

More specifically, a 64x64 CTU node (with a quadtree depth of 0) cannot be split based on the split_cu_flag corresponding to the CTU node and becomes a 64x64 CU; or it can be split into four 32x32 nodes (with a quadtree depth of 1). Each of the four 32x32 nodes may or may not be further split based on the split_cu_flag corresponding to the node. If a 32x32 node keeps splitting, four 16x16 nodes (with a quadtree depth of 2) are generated. The rest can be deduced by analogy until no node is split. Thus, one CTU is split into one group of CUs. The minimum size (size) of a CU is specified in the SPS. For example, 8x8 is the minimum CU size. In the above recursive partitioning process, if the node size is equal to the minimum CU size, the node does not need to be further partitioned by default, and the node partitioning flag does not need to be added to the bitstream.

After it is known through parsing that the node is a leaf node and the leaf node is a CU, coding information (including information such as prediction mode and transform coefficient of the CU, such as the coding_unit() syntax structure in H.266 ) corresponding to CU is analyzed further. Then, at the CU, decoding processing such as prediction, inverse quantization, inverse transform, and loop filtering is performed based on the encoding information to generate a reconstructed image corresponding to the CU. In a quadtree (QT) structure, a CTU may be divided into a group of CUs of appropriate sizes based on a local image feature. For example, a flat area is split into larger CUs, while a richly textured area is split into smaller CUs.

The mode of dividing the CTU into a group of CUs corresponds to the coding tree. The specific coding tree to be used by the CTU is typically determined by the rate distorting optimization (RDO) encoder technology. The encoder considers multiple CTU split modes, and each split mode corresponds to one rate distortion cost (RD cost). The encoder compares the cost RDs for the split modes that are being attempted to find the split mode with the minimum RD cost as the optimal CTU split mode for actual CTU encoding. All CTU split modes checked by the encoder must match the split rule specified by the decoder so that the CTU split modes can be correctly identified by the decoder.

Splitting on a vertical binary tree (binary tree, BT): a block is vertically split into two rectangular blocks of the same size. Fig. 7B shows an example of vertical partitioning of a binary tree.

Horizontal splitting of a binary tree: a block is split horizontally into two rectangular blocks of the same size. Fig. 7C shows an example of horizontal partitioning of a binary tree.

Vertical splitting of the ternary tree at the center (TT): the block is vertically divided into three rectangular blocks, so that the two side blocks are the same size and the size of the central block is the sum of the sizes of the two side blocks. Fig. 7D is an example of vertically splitting a ternary tree down the center.

Horizontal splitting of a ternary tree in the center: the block is horizontally split into three rectangular blocks, so that the two side blocks are the same size and the size of the central block is the sum of the sizes of the two side blocks. Fig. 7E shows an example of horizontal splitting of a ternary tree along the center.

Specific separation methods in FIG. 7B-fig. 7E are similar to the descriptions in FIG. 7A, and details are not described here again. In addition, the QT and BT/TT cascading separation mode, which is called QT-BTT for short, can be used. That is, a node in the level 1 coding tree can only be subdivided into child nodes by Q, and a leaf node in the level 1 coding tree is the root node of the level 2 coding tree; a node in the layer 2 coding tree may be split into child nodes using one of the following four splitting modes: horizontal binary split, vertical binary split, horizontal ternary split, and vertical ternary split; the leaf node of the layer 2 coding tree is the coding block. In particular, binary tree splitting and quadtree splitting are performed in a cascaded manner, which for brevity, may be the QTBT splitting mode. For example, the CTU is first split by QT, and the QT leaf node may be further split by BT, as shown in FIG. 8. On the right side of FIG. 8 each endpoint represents one node. One node connected to four solid lines represents a quadtree split and one node connected to two dashed lines represents a binary tree split. The node resulting from the split may be referred to as the child node of the node, which is a child node for short. There are 13 leaf nodes among child nodes a through m, and each leaf node represents one CU. At a binary tree node, 1 represents a vertical split and 0 represents a horizontal split. The CTU is divided into 13 CUs: a to m, as shown on the left side of FIG. 8. In the QTBT split mode, each CU has a QT depth (Quad-tree depth, QT depth) and a BT depth (Binary tree depth, BT depth). The QT depth represents the QT depth of the QT leaf node to which the CU belongs, and the BT depth represents the BT depth of the BT leaf node to which the CU belongs. For example, in FIG. 8, QT depths a and b are 1, BT depths a and b are 2; the QT depths for c, d, and e are 1; the BT depths for c, d, and e are 1; the QT depths for f, k and l are 2, the BT depths for f, k and l are 1; the depths of QT i and j are equal to 2, the depths of BT i and j are equal to 0; the QT depths for g and h are 2, the BT depths for g and h are 2; the QT depth m is 1, the BT depth m is 0. If the CTU is divided into only one CU, the QT depth of the CU is 0 and the BT depth of the CU is 0.

For a block associated with a particular depth, encoder 20 determines which split type (including no additional split) is used and explicitly or implicitly (eg, split type can be derived from a predefined rule) signals the determined split type to decoder 30 The encoder 20 may determine which type of split to use based on the rate distortion cost to test a different split type for the block.

If a 2xM chroma block, particularly a 2x2, 2x4, or 2x8 chroma block, is generated by splitting a node, the chroma encoding and decoding efficiency is relatively low, and the hardware decoder processing cost is relatively high. This is unfavorable for the hardware decoder implementation. When the chrominance block of the current node is not further divided, in this embodiment of the present invention, only the luminance block of the current node can be divided, thereby improving encoding and decoding efficiency, reducing the maximum codec bandwidth, and facilitating implementation. codec. Specifically, in this embodiment of the present invention, when the child nodes generated by splitting a node using the split mode include a chrominance block whose side length is the first threshold value (or includes a chroma block whose side length is less than the second threshold values), the luminance block contained in the node is divided using this separation mode, the chrominance block included in the node is not further divided. In this mode, it is possible to avoid generating a chrominance block whose side length is the first threshold value (or the side length is less than the second threshold value). In a particular implementation, the first threshold may be 2 and the second threshold may be 4. The following provides detailed descriptions with reference to Embodiments 1-3. In this embodiment of the present invention, descriptions are provided using the YUV4:2:0 video data format, and a similar method can be used for YUV4:2:2 data.

In the extended SCC HEVC standard, an Intra Block Copy (IBC) coding tool is adopted and is mainly used to improve the efficiency of encoding screen video content. The IBC mode is a block level coding mode. On the encoder side, block matching (BM) is used to find the optimal block vector or motion vector for each CU. The motion vector in this document is mainly used to represent the displacement from the current block to the reference block, and is also referred to as the displacement vector. The reference block is the reconstructed block in the current image. The IBC mode can be considered as a third prediction mode different from the intra prediction mode or the inter prediction mode. To save storage space and simplify the decoder, VTM4's IBC mode allows only the reconstructed portion of a predefined region of the current CTU to be used for prediction.

The VTM uses a flag at the CU level to indicate whether IBC mode is used for the current CU. The IBC mode is subdivided into the IBC AMVP mode, the IBC skip mode, or the IBC merge mode.

Embodiment 1

Fig. 9 is a flowchart of a method 900 according to Embodiment 1 of the present invention.

Step 901: determine whether to split the current node if the current node includes a luminance block and a chrominance block.

If the current node is not further divided into child nodes, the current node is a coding unit (CU), and step 910 is performed to obtain information about the coding unit through parsing; or, if the current node needs to be split, step 902 is executed.

Embodiment 1 of the present invention may be implemented by a video decoding apparatus, namely the apparatus described in any of FIGS. 3 - fig. five.

Embodiment 1 of the present invention may alternatively be implemented by a video encoding device, namely the device described in any of FIGS. 2, fig. 4 and FIG. five.

When Embodiment 1 is implemented by the video decoder, step 902: The video decoder parses the bitstream to determine the split mode of the current node. The split mode of the current node can be at least one of quadrant split (QT), horizontal binary split (horizontal BT), horizontal triple split (horizontal TT), vertical binary split (Vertical BT) and vertical triple split (Vertical TT) or can be different split mode. This is not limited to this embodiment of the present invention. Information about the split mode of the current node is usually transmitted in the bitstream, and the split mode of the current node can be obtained by parsing the corresponding syntax element in the bitstream.

When Embodiment 1 is implemented by a video coding device, step 902: determine how to split the current node.

Step 904: determine, based on the splitting mode of the current node and the size of the current node, whether to split the chrominance block of the current node; and, when the current node's chrominance block is no longer split, execute step 906; or, when the current node's chrominance block is to be split, execute step 908.

In particular, an implementation may determine whether a chrominance block whose side length is the first threshold (or a chrominance block whose side length is less than the second threshold) is generated by splitting the current node based on the splitting mode of the current node. If it is determined that the child node generated by splitting the current node includes a chrominance block whose side length is the first threshold value (or includes a chroma block whose side length is less than the second threshold value), the current node's chrominance block is not further divided . For example, the first threshold may be 2 and the second threshold may be 4.

In this embodiment of the present invention, the chrominance block whose side length is the first threshold is the chrominance block whose width or height is the first threshold.

In another implementation, for example, when any of conditions 1 - conditions 5 is true, it may be determined that the chrominance block of the current node is not further divided; otherwise, it is determined that the current node's chrominance block is to be split:

condition 1: the width of the current node is equal to twice the second threshold value, and the division mode of the current node is vertical binary division;

condition 2: the height of the current node is equal to twice the second threshold value, and the division mode of the current node is horizontal binary division;

condition 3: the width of the current node is four times the second threshold value, and the division mode of the current node is vertical triple division.

condition 4: the height of the current node is four times the second threshold, and the division mode of the current node is horizontal triple division; or

condition 5: the width of the current node is equal to twice the second threshold value, and the division mode of the current node is a quadruple division.

Typically, the width of the current node is the width of the luminance block corresponding to the current node, and the height of the current node is the height of the luminance block corresponding to the current node. In a particular implementation, for example, the second threshold may be 4.

In a third implementation, it may be determined whether a chrominance block whose width is the first threshold (or a chrominance block whose width is less than the second threshold) is generated by splitting the current node based on the splitting mode of the current node. If it is determined that the child node generated by splitting the current node includes a chrominance block whose width is the first threshold (or includes a chroma block whose width is less than the second threshold), the current node's chrominance block is not additionally split. For example, the first threshold may be 2 and the second threshold may be 4.

In a fourth implementation, it may be determined whether a chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node. If it is determined that the child node generated by splitting the current node includes a chroma block whose number of chroma samples is less than the third threshold, the chroma block of the current node is not further divided. For example, the third threshold may be 16. In this case, a chroma block whose number of chroma samples is less than 16 includes, but is not limited to, a 2x2 chroma block, a 2x4 chroma block, and a 4x2 chroma block. The third threshold may be 8. In this case, a chroma block whose number of chroma samples is less than 8 includes, but is not limited to, a 2x2 chroma block.

Specifically, if condition 1 or condition 2 is true, it can be determined that a chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node; otherwise, it may be determined that no chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node:

condition 1: the product of the width and height of the current node is less than 128, and the division mode of the current node is vertical binary division or horizontal binary division; or

condition 2: The product of the width and height of the current node is less than 256, and the split mode of the current node is vertical triple split, horizontal triple split, or quadruple split.

Specifically, in another implementation, if either condition 3 or condition 4 is met, it may be determined that a chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node; otherwise, it may be determined that no chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node:

condition 3: the product of the width and height of the current node is 64, and the split mode of the current node is vertical binary split, horizontal binary split, quadruple split, horizontal triple split, or vertical triple split; or

condition 4: The product of the width and height of the current node is 128, and the split mode of the current node is vertical triple split or horizontal triple split.

In a fifth implementation, it may be determined whether a chrominance block whose height is the first threshold (or a chrominance block whose height is less than the second threshold) is generated by splitting the current node based on the splitting mode of the current node. If it is determined that the child node generated by splitting the current node includes a chrominance block whose height is the first threshold (or a chrominance block whose height is less than the second threshold), the current node's chroma block is not further divided. For example, the first threshold may be 2 and the second threshold may be 4.

Step 906: Divide the luma block of the current node based on the split mode of the current node to obtain child nodes (which may also be referred to as child nodes of the luma block, luma nodes for short) of the current node. Each child node only includes a luminance block. The chroma block of the current node is not further split and becomes a coding block including only the chroma block.

Perhaps, as shown in Fig. 10, step 906 may further include step 9062: parse the current node luminance block to obtain prediction information and residual information of each of the sub-regions in the current node luminance block, where each sub-region corresponds to one child node.

In particular, block 9062 may be implemented using any of the following methods:

Method 1: Optionally, do not separate each default luminance block child node (that is, each luminance node is a coding block and one luminance block child node corresponds to one coding block including only the luminance block), and sequentially parse the coding block data for the child nodes luminance block to obtain prediction information and residual information of each luminance block. The luminance node luminance block is a subregion in the current node luminance block, and the luma node luminance blocks constitute the current node luminance block.

Method 2: determine whether to continue the additional sequential division of the child nodes of the brightness block; and, when the child nodes need to be further divided, parse the child node separation mode and the corresponding coding block data. More specifically, if the luminance node is not further divided, coding block data corresponding to the luminance node is parsed to obtain prediction information and residual information that correspond to the luma node luminance block; or, if the luma node continues to split, determine whether to split the child nodes (note that the child node still includes only the luma block) of the luma node until the prediction information and the residual information of each block subregions are determined. the brightness of the current node.

The prediction information includes, but is not limited to, a prediction mode (indicating an intra prediction mode or an inter prediction mode), an intra prediction mode, motion information, and/or the like. The intra-luma block prediction mode may be one of planar mode (Planar Mode), DC mode (DC Mode), angular mode (angular Mode), and derived chroma mode (chroma derived mode, DM). The motion information may include information such as prediction direction (forward, backward, or bi-directional), reference index, and/or motion vector.

The residual information includes a coded block flag (CBF), a transform coefficient and/or a transform type (eg, DCT-2, DST-7, or DCT-8), and the like.

Perhaps, as shown in Fig. 10, step 906 may further include step 9064: obtain prediction information and/or residual chrominance block information.

In particular, block 9064 may include block 90642 and block 90644. Block 90642 may be block 90642A or block 90642B.

Step 90642A specifically includes:

Get the prediction mode for the given luminance block position of the current node as the chrominance block prediction mode of the current node. The position of the top left corner of the current node's luminance block can be expressed as (x0, y0) and its size is WxH. In this case, the specified position may include, but is not limited to, top left corner, bottom right corner (x0 + W - 1, y0 + H - 1), center (x0 + W/2, y0 + H/2), (x0 + W/2, 0) or (0, y0 + H/2) luminance blocks or the like. The prediction mode indicates whether intra prediction or inter prediction is performed for a pixel at a given position, such as the information indicated by the pred_mode_flag syntax element in HEVC. For example, the VTM may determine whether the prediction mode for a given position is the IBC mode based on information indicated by the pred_mode_ibc_flag syntax element.

If the prediction mode for a given position is inter prediction, one of the following methods is used to determine the chrominance block prediction mode:

Method 1: Perform inter-prediction for a chroma block to obtain motion information for a given position as motion information for a chroma block.

Method 2: Perform inter-prediction on a chrominance block, and divide the chroma block into chrominance prediction sub-blocks (where the size of the chroma prediction sub-block is, for example, two width chroma samples and two height chroma samples) and obtain motion information of the chroma prediction sub-blocks as follows:

If inter-prediction is performed for luma blocks at luminance image positions corresponding to chrominance prediction subblocks, motion information at luma image positions corresponding to chrominance prediction subblocks is used as motion information of the chrominance prediction subblock; otherwise, motion information for a given position is obtained as motion information of chrominance prediction sub-blocks.

For a YUV4:2:0 image, coordinates of a chroma prediction sub-block in the chroma image are denoted as (xC, yC). In this case, the position coordinates of the luminance image corresponding to the chrominance prediction subblock are (xC << 1, yC << 1).

Method 3: parse pred_mode_flag to determine whether intra or inter prediction is performed for a chrominance block; and, if intra prediction is performed for a chrominance block, parse the intra prediction mode from the bitstream as an intra prediction mode of the chrominance block; or, if inter-prediction is performed for the chrominance block, obtain the motion information for the given position as the motion information for the chrominance block.

Method 4: Parse pred_mode_flag to determine whether intra or inter prediction is performed for a chrominance block; and, if intra prediction is performed in the chrominance block, parse the intra prediction mode from the bit stream as the intra prediction mode of the chrominance block, where the intra prediction mode may be one of the inter-component linear model mode and the DM mode, and the intra luminance prediction mode corresponding to the DM mode , is set to planar mode; or, if inter-prediction is performed on a chroma block, divide the chroma block into chroma prediction sub-blocks, where motion information of the chroma prediction sub-blocks is obtained as follows:

If inter-prediction is performed for luma blocks at luminance image positions corresponding to chrominance prediction subblocks, motion information at luma image positions corresponding to chrominance prediction subblocks is used as motion information of the chrominance prediction subblock; otherwise, motion information for a given position is obtained as motion information of chrominance prediction sub-blocks.

The context model used to parse the pred_mode_flag is the given model, eg model number 2.

If the prediction mode for the given position is intra prediction, intra prediction is performed for the chrominance block, and the intra prediction mode is parsed from the bit stream as the intra prediction mode of the chrominance block. Alternatively, it is directly determined that the chrominance block intra prediction mode is one of DC mode, planar mode, angular mode, cross-component linear model mode, or DM mode.

If the prediction mode for the given position is the IBC mode, the chrominance block is predicted in the IBC mode to obtain displacement vector information for the given position as the chrominance block displacement vector information; or

if the prediction mode for a given position is the IBC mode, the chroma block prediction mode is determined based on the pred_mode_ibc_flag flag:

1) if pred_mode_ibc_flag is 1, the IBC mode for the chrominance block is used; more specifically, the IBC prediction method for a chrominance block may be a method in VTM 4.0, that is, the chrominance block is divided into 2x2 subblocks, and the offset vector of each subblock is equal to the offset vector of the luma region corresponding to the subblock; or

2) if pred_mode_ibc_flag is 0, the intra-prediction mode or the inter-prediction mode is used for the chrominance block.

When the intra prediction mode is used, a syntax element from the bit stream is parsed to determine the intra chrominance prediction mode. Alternatively, it is directly determined that the chroma block intra prediction mode belongs to the intra chroma prediction mode set. The set of intra chrominance prediction modes includes DC mode, planar mode, angular mode, cross-component linear model mode, and DM mode.

When the inter prediction mode is used, motion information for a given position can be obtained as motion information of a chrominance block.

It should be noted that when there is no pred_mode_ibc_flag in the bitstream, if the type of the picture in which the current node is located is I-frame / I-segment, and the IBC mode is allowed to be used, the default pred_mode_ibc_flag is 1, that is, the IBC mode is used for default color block; or, if the type of picture in which the current node is located is a P/B frame/segment, pred_mode_ibc_flag defaults to 0.

In the VTM, it can be determined whether the prediction mode for a given position is the IBC mode based on the information indicated by the pred_mode_ibc_flag syntax element. For example, if pred_mode_ibc_flag is 1, this indicates that the IBC prediction mode is being used; or, if pred_mode_ibc_flag is 0, this indicates that the IBC mode is not used. When there is no pred_mode_ibc_flag in the bitstream, if in the I-frame/I-slot the value of pred_mode_ibc_flag is equal to the value of sps_ibc_enabled_flag; if in a P frame/segment or a B frame/segment, pred_mode_ibc_flag is equal to 0. When sps_ibc_enabled_flag is equal to 1, it indicates that the current picture is allowed to be used as a reference picture in the current picture decoding process; or, when sps_ibc_enabled_flag is 0, it means that the current frame is not allowed to be used as a reference picture in the current picture decoding process.

The chroma block intra prediction mode may be one of DC mode, planar mode, angular mode, cross-component liner model (CCLM) mode, and derived chroma mode. (chroma derived mode, DM), such as DC mode, planar mode, angular mode, cross-component linear model mode, and VTM derived chroma mode.

Step 90642B specifically includes:

Obtain the prediction modes for the set of luminance blocks of the current node and determine the prediction mode of the chrominance block corresponding to the current node using the following method:

If intra prediction is performed on the entire plurality of luma blocks, intra prediction is performed on the chrominance block, and the intra prediction mode is parsed from the bit stream as the intra prediction mode of the chrominance block.

If inter-prediction is performed on the entire set of luminance blocks, one of the following methods is used to determine the chrominance prediction mode:

Method 1: Perform inter-prediction for a chrominance block to obtain motion information for a given position as motion information for a chrominance block. The set position has the same meaning as in Embodiment 1.

Method 2: parse the pred_mode_flag to determine whether intra or inter prediction is performed for a chrominance block; and, if intra prediction is performed for the chrominance block, parse the intra prediction mode from the bitstream as the intra prediction mode of the chrominance block; or, if inter-prediction is performed for the chrominance block, obtain the motion information for the given position as the motion information for the chrominance block.

If inter prediction and intra prediction are applied to a plurality of luma blocks, the chroma block mode information may be determined in one of the following ways:

(1) if the prediction mode for the given position is inter prediction, inter prediction is performed for the chrominance block to obtain motion information for the given position as motion information of the chrominance block;

(2) if the prediction mode for the given position is intra prediction, intra prediction is performed on the chrominance block, and the intra prediction mode is parsed from the bit stream as the intra prediction mode of the chrominance block; or it is directly determined that the chrominance block intra prediction mode is one of DC mode, planar mode, angular mode, cross-component linear model mode, or DM mode;

(3) if the prediction mode for the given position is the IBC mode, the chrominance block is predicted in the IBC mode to obtain the offset vector information for the given position as the offset vector information of the chrominance block; and

(4) the chrominance prediction mode is directly listed as one mode in the mode set, where the mode set includes AMVP mode, IBC mode, skip mode, DC mode, planar mode, angular mode, cross-component linear model mode, and DM mode.

Step 90644: analyze the residual information of the chrominance block. The residual information of the chrominance block is contained in the transform block. The default conversion type may be DCT-2.

Step 908: Divide the current node into child nodes, where each child node includes a luminance block and a chrominance block. Step 901 is performed on each child node, and parsing continues for the child node split mode to determine if the child node (which is also referred to as a node) should be further split.

After obtaining the sub-region separation mode of the luminance block and prediction information and residual information of each of the sub-regions, inter prediction processing or intra prediction processing may be performed for each sub-region based on the corresponding sub-region prediction mode to obtain an inter-prediction image or an intra-prediction image for the sub-region. Then, dequantization and inverse transform processing of the transform coefficient are performed based on the residual information of each sub-region to obtain a residual image, and the residual image is superimposed on the predicted image in the corresponding sub-region to generate a reconstructed luminance block image.

After obtaining prediction information and residual chroma block information, inter prediction processing or intra prediction processing may be performed on the chroma block based on the chroma block prediction mode to obtain an inter prediction image or intra chroma block image prediction. Then, dequantization and inverse transformation processing of the transform coefficient based on the residual chrominance block information are performed to obtain a residual image, and the residual image is superimposed on the predicted chrominance block image to generate a reconstructed chrominance block image.

In Embodiment 1 of the present invention, when the chrominance block of the current node is not further divided, the method can be used to separate only the luma block of the current node, thereby improving encoding and decoding efficiency, reducing the maximum codec bandwidth, and simplifying its implementation.

Embodiment 2

Compared to Embodiment 1, the following constraint is added to step 9062: luma nodes (i.e., child nodes of luminance blocks) use the same prediction mode, i.e., either intra-prediction or inter-prediction is performed at each luminance node. Other steps are the same as those in Embodiment 1, and details are not described again.

To use the same prediction mode for luma nodes, any of the following methods can be used:

Method 1: If the current frame is an I-frame, all child nodes of the current node perform intra-prediction by default; or, if the current frame is a P-frame or a B-frame, the first node (which may be the first child node for short) on which parsing processing is performed is parsed to obtain the prediction mode of the first node, and the prediction mode of the remaining child node (which is the brightness node for short) defaults to the prediction mode of the first node on which parsing processing is performed; or

method 2: if the current frame is an I-frame, perform intra-prediction on all child nodes of the current default node; or, if the current frame is a P-frame or a B-frame, inter-prediction is performed on all child nodes of the current default node.

Option 3 implementation

Fig. 11 is a flowchart 1100 of a method according to Embodiment 3 of the present invention. Embodiment 3 is the same as Embodiment 1 except for step 1104.

Step 1104: Determine, based on the partitioning mode of the current node, the size of the current node and the prediction mode of the first node on which parsing processing is performed (which may be the first child node for short) in the current node, whether to split the chrominance block of the current node, where the first child is the node includes only the luma block. The same prediction mode is performed for multiple child nodes of the current node. Each child node only includes a luminance block.

Whether the division mode of the current node and the size of the current node should be determined, or whether the prediction mode of the first child node is determined first is not limited in this embodiment of the present invention.

Based on Embodiment 1 or 2, in Embodiment 3, the chrominance block splitting mode of the current node corresponding to the prediction information parsing mode and corresponding to the residual information parsing mode is determined with reference to the prediction mode of the first child node of the current node.

In the implementation, based on the split mode of the current node and the size of the current node, it is determined that the child node generated by splitting the current node includes a chrominance block whose side length is equal to the first threshold value, or whose side length is less than the second threshold value, and the prediction mode the first child node is an intra prediction; in this case, the current node's chrominance block is not split. Similar to Embodiment 1, for example, the first threshold may be 2 and the second threshold may be 4.

In this embodiment of the present invention, the chrominance block whose side length is the first threshold is the chrominance block whose width or height is the first threshold.

In another implementation, when the prediction mode of the first child node is intra prediction and any of conditions 1-5 are met:

condition 1: the width of the current node is equal to twice the second threshold value, and the division mode of the current node is vertical binary division;

condition 2: the height of the current node is equal to twice the second threshold value, and the division mode of the current node is horizontal binary division;

condition 3: the width of the current node is four times the second threshold value, and the division mode of the current node is vertical triple division;

condition 4: the height of the current node is four times the second threshold, and the division mode of the current node is horizontal triple division; or

condition 5: if the width of the current node is twice the second threshold value and the division mode of the current node is four times division, the chrominance block of the current node is not further divided.

Typically, the width of the current node is the width of the luminance block corresponding to the current node, and the height of the current node is the height of the luminance block corresponding to the current node. In a particular implementation, for example, the second threshold may be 4.

When the prediction mode of the first child node is intra prediction similar to the first embodiment, in the third implementation, it can be determined whether a chrominance block whose width is the first threshold value (or a chrominance block whose width is less than the second threshold value) is generated by dividing the current node based on the partitioning mode of the current node. If it is determined that the child node generated by dividing the current node includes a chrominance block whose width is the first threshold value (or a chrominance block whose width is less than the second threshold value) and the prediction mode of the first child node is intra prediction, the chrominance block of the current node is not further divided. For example, the first threshold may be 2 and the second threshold may be 4.

When the prediction mode of the first child node is intra prediction similar to the first embodiment, in the fourth implementation, it can be determined whether a chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node. If it is determined that the child node generated by dividing the current node includes a chrominance block whose number of chroma samples is less than the third threshold, and the prediction mode of the first child node is intra prediction, the chrominance block of the current node is not further divided. For example, the third threshold may be 16. In this case, a chroma block whose number of chroma samples is less than 16 includes, but is not limited to, a 2x2 chroma block, a 2x4 chroma block, and a 4x2 chroma block. The third threshold may be 8. In this case, a chroma block whose number of chroma samples is less than 8 includes, but is not limited to, a 2x2 chroma block.

Specifically, if either condition 1 or condition 2 is true, it can be determined that a chrominance block whose number of chroma samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node; otherwise, it may be determined that no chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node:

condition 1: the product of the width and height of the current node is less than 128, and the division mode of the current node is vertical binary division or horizontal binary division; or

condition 2: The product of the width and height of the current node is less than 256, and the split mode of the current node is vertical triple split, horizontal triple split, or quadruple split.

Specifically, in another implementation, if either condition 3 or condition 4 is met, it may be determined that a chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node; otherwise, it may be determined that no chrominance block whose number of chrominance samples is less than the third threshold is generated by splitting the current node based on the splitting mode of the current node:

condition 3: the product of the width and height of the current node is 64, and the division mode of the current node is vertical binary division, horizontal binary division, quadruple division, horizontal triple division, or vertical triple division; or

condition 4: The product of the width and height of the current node is 128, and the split mode of the current node is vertical triple split or horizontal triple split.

When the prediction mode of the first child node is intra prediction similar to the first embodiment, in the fifth implementation, it can be determined whether a chrominance block whose height is the first threshold value (or a chrominance block whose height is less than the second threshold value) is generated by dividing the current node based on the partitioning mode of the current node. If it is determined that the child node generated by dividing the current node includes a chroma block whose height is the first threshold (or a chroma block whose height is less than the second threshold), and the prediction mode of the first child node is intra prediction, the chroma block the current node is not further split. For example, the first threshold may be 2 and the second threshold may be 4.

If the chrominance block of the current node is not further divided, the chrominance block of the current node becomes a coding block including only the chrominance block. Method 1100 may further include: obtaining prediction information and/or residual chroma block information.

In another implementation, based on the splitting mode of the current node and the size of the current node, it is determined that a child node generated by splitting the current node includes a chroma block whose side length is less than a threshold value. If the prediction mode of the first child node is inter-prediction, the chrominance block of the current node is divided based on the split mode of the current node. Perhaps the motion information of the corresponding child node of the chrominance block is determined based on the motion information of the child node of the current node. For example, the motion information of a chrominance block child node of the current node may be set as the motion information of the corresponding luminance node (ie, the motion information of each child node of the chrominance block need not be parsed from the bitstream). The child nodes of the chrominance block are parsed to obtain residual information about the child nodes of the chrominance block.

When the prediction mode of the first child node is inter-prediction, and any of the following conditions are met:

condition 1: the width of the current node is equal to twice the second threshold value, and the division mode of the current node is vertical binary division;

condition 2: the height of the current node is equal to twice the second threshold value, and the division mode of the current node is horizontal binary division;

condition 3: the width of the current node is four times the second threshold value, and the division mode of the current node is vertical triple division;

condition 4: the height of the current node is four times the second threshold, and the division mode of the current node is horizontal triple division; or

condition 5: if the width of the current node is equal to twice the second threshold value and the division mode of the current node is four times division, the chrominance block of the current node still needs to be divided.

Typically, the width of the current node is the width of the luminance block corresponding to the current node, and the height of the current node is the height of the luminance block corresponding to the current node. In a particular implementation, for example, the second threshold may be 4.

In Embodiment 3, a chrominance block separation mode corresponding to the prediction information parsing mode and corresponding to the residual information parsing mode can also be determined based on the luma node prediction mode. In this way, greater flexibility is achieved. In addition, when the luma node prediction mode is intra prediction, the chrominance block of the current node is not further divided, thereby improving chroma encoding and decoding efficiency, reducing the maximum codec bandwidth, and facilitating codec implementation.

Table 1 shows some syntax structures at the CU level. If the current node is not further divided into child nodes, the current node is a coding block, and the coding block prediction block is parsed according to the following syntax structures.

skip_flag is a flag representing the skip mode. When the value of skip_flag is 1, it indicates that the current CU is in skip mode; or when the value of skip_flag is 0, it indicates that the current CU does not use the skip mode.

merge_flag is a flag representing direct mode. When the value of merge_flag is 1, it indicates that the current CU is in merge mode; or when the value of merge_flag is 0, it indicates that the merge mode is not used.

cu_pred_mode is a flag representing the coding block prediction mode. When the value of cu_pred_mode is 1, it indicates that the current coding block is using intra prediction mode; or, when the value of cu_pred_mode is 0, it indicates that the current coding block is using the common inter prediction mode.

Table 1

Table 2 shows some parsing at the CU level. Table 2 is just an example. In table 2, the value of skip_flag is the same as skip_flag in table 1, and the value of pred_mode_flag is the same as cu_pred_mode in table 1.

cu_skip_flag is a flag representing the skip mode. When the value of cu_skip_flag is 1, it indicates that the current CU is in skip mode; or, when the value of cu_skip_flag is 0, it indicates that the current CU does not use skip mode.

merge_flag is a flag representing direct mode. When the value of merge_flag is 1, it indicates that the current CU is in merge mode; or, when the value of merge_flag is 0, it indicates that the merge mode is not used.

pred_mode_flag is a flag representing the coding block prediction mode. When the value of pred_mode_flag is 1, this indicates that the intra prediction mode is used for the current prediction block; or, when the value of pred_mode_flag is 0, it indicates that the current prediction block is using the common inter prediction mode. If the value of pred_mode_flag is 1, the value of CuPredMode[x0][y0] is MODE_INTRA; or, if the value of pred_mode_flag is 0, the value of CuPredMode[x0][y0] is MODE_INTER.

table 2

In vertical binary splitting (or horizontal binary splitting) mode, an 8xM (or Mx8) node is split into two 4xM (or Mx4) child nodes. Similarly, a 16xM (or Mx16) node is split into four 4xM (or Mx4) children and one 8xN (or Nx8) child in a vertical extended quadruple split (or horizontal extended quadruple split). Similarly, a 16xM (or Mx16) node is split in vertical ternary split (or horizontal ternary split) mode to generate two 4xM (or Mx4) children and one 8xM (or Mx8) child. For the YUV4:2:0 data format, the resolution of the chrominance component is 1/2 of the luma component. That is, a 4xM node includes one 4xM luminance block and two 2x (M/2) chrominance blocks. For a hardware decoder, the cost of processing small blocks (especially 2x2, 2x4 and 2x8 sizes) is relatively high. However, in this split mode, small blocks of 2x2, 2x4, etc. are generated, which is unfavorable for the hardware decoder implementation. For a hardware decoder, the complexity of processing small blocks is relatively high, which is specifically embodied in the following three aspects.

(1) Technical tasks of intra prediction: in the design of equipment to improve the processing speed, it is common to process 16 pixels once for intra prediction at the same time, and a small block of 2x2, 2x4, 4x2 or the like includes less than 16 pixels, which reduces the processing performance of the internal predictions.

(2) Coefficient coding technical problems: In HEVC, transform coefficient coding is based on a coefficient group (coefficient group, CG) including 16 coefficients, but a small block of 2x2, 2x4, 4x2 or the like includes four or eight transform coefficients . As a result, in order to support coefficient coding of these small blocks, coefficient groups including four coefficients and eight coefficients must be added; hence, the implementation complexity increases.

(3) Technical challenges of inter prediction: small block inter prediction has a relatively high data bandwidth requirement, and also affects the decoding processing speed.

When a node is further divided based on a partition mode, and one of the generated child nodes includes a chrominance block whose side length is 2, the luminance block included in the child node continues to be further divided in this partition mode, and the chrominance block included in the child node is not further divided. This mode can avoid generating a chrominance block whose side length is 2, reduce the maximum throughput of the decoder, and facilitate the implementation of the decoder. Further, a method for determining a chrominance block prediction mode based on a luminance block prediction mode is provided, effectively improving coding efficiency.

The method provided in the present invention can be applied to the video codec in the above embodiment.

Implementation Option 4

This embodiment relates to a block division mode in video decoding. The video data format in this embodiment is the YUV4:2:0 format. A similar mode can be used for YUV4:2:2 data.

Step 1: parse partition mode S of node A, where if node A continues to split, step 2 is performed; or, if the current node is not further divided into child nodes, the current node corresponds to one coding block, and information about the coding block is obtained by parsing.

The splitting mode of node A may be at least one of quadtree splitting, vertical binary splitting, horizontal binary splitting, vertical ternary splitting, and horizontal ternary splitting, or may be another splitting mode. Node A split mode is not limited to the present invention. Information about the split mode of the current node may be transmitted in the bitstream, and the split mode of the current node can be obtained by parsing the corresponding syntax element in the bitstream. Alternatively, the split mode of the current node may be determined according to a predetermined rule and is not limited to the present invention.

Step 2: determine whether the chrominance block of at least one child node B in the child nodes obtained by partitioning node A based on partition mode S is a small block (or has the width, height and/or partition mode of node A and /or the width and height of node B satisfy at least one of the conditions). If the chrominance block of at least one child node B in the child nodes obtained by splitting node A is a small block, steps 3 to 6 are performed.

In particular, one of the following methods may be used to determine whether a chroma block of at least one child node B of node A is a sub-block:

(1) If the chrominance block of at least one child node B of node A has a size of 2x2, 2x4, or 4x2, the chroma block of at least one child node B of node A is a small block;

(2) if the width or height of the chrominance block of at least one child node B of node A is 2, the chrominance block of at least one child node B of node A is a small block;

(3) if node A includes 128 luminance samples and ternary tree splitting is performed at node A, or node A includes 64 luma samples and binary tree splitting is performed at node A, quadtree split mode or ternary tree split mode, block the chromaticity of at least one child node B of node A is a small block;

(4) if node A includes 256 luminance samples and the node splits in ternary tree split mode or quadtree split mode, or node A includes 128 luma samples, the node splits in binary tree split mode, the chrominance block is at least at least one child node B node A is a small block;

(5) if node A includes N1 luma samples and ternary tree splitting is performed at node A, where N1 is 64, 128, or 256;

(6) if node A includes N2 luma samples and a quadtree split is performed at node A, where N2 is 64 or 256; or

(7) if node A includes N3 luma samples and node A is split in binary tree split mode, where N3 is 64, 128, or 256.

It should be noted that node A includes 128 luminance samples can also be described as that the area of the current node is 128, or the product of the width and height of node A is 128. Details are not described.

Step 3: Limit the execution of intra prediction or inter prediction for all coding blocks in the coverage area of node A. For intra prediction and inter prediction for all coding blocks, parallel processing of small blocks can be realized by hardware, thereby improving encoding and decoding performance.

One of the following methods may be used to determine whether intra prediction or inter prediction is performed for all coding blocks in the coverage area of node A.

Method 1: The determination is made based on a flag in the syntax table.

If the chrominance block of at least one child node B obtained by partitioning node A based on the partition mode S is a small block (and the chroma block of node A is not a small block), the cons_pred_mode_flag flag is parsed from the bitstream. When the value of cons_pred_mode_flag is 0, this indicates that inter-prediction is performed for all coding blocks in the coverage area of node A; or, when the value of cons_pred_mode_flag is equal to 1, it indicates that intra prediction is performed for all coding blocks in the coverage area of node A. cons_pred_mode_flag may be a syntax element to be parsed in the block splitting process. When a syntax element is parsed, the cu_pred_mode of the coding block in the coverage area of node A may no longer be parsed, and the value of cu_pred_mode is the default value corresponding to the value of cons_pred_mode_flag.

It should be noted that if only the intra prediction mode can be used for the child nodes of node A, for example, node A is in an intra-picture (that is, a picture type in which node A is an intra-type or I-type), or node A is in the internal image, and IBC technology is not used for the sequence, the default value of cons_pred_mode_flag is 1, cons_pred_mode_flag is not present in the bitstream. The IBC technology may belong to external prediction or may belong to intra prediction.

Method 2: The determination is performed based on the prediction mode of the first node in the region of node A.

The prediction mode of the first coding block B0 (where the prediction mode of the first coding block B0 is not limited) in the region of node A is analyzed. If the prediction mode B0 is intra prediction, intra prediction is performed for all coding blocks in the coverage region of node A; or, if the prediction mode of B0 is inter prediction, inter prediction is performed for all coding blocks in the coverage area of node A.

Step 4: determine the chrominance block separation mode and the luma block separation mode of node A based on the prediction mode used for coding blocks in the coverage area of node A.

If the intra prediction mode is used for all coding blocks in the coverage area of node A, the luminance block of node A is divided based on the division mode S to obtain N nodes of the luminance coding tree; and node A's chroma block is not split and corresponds to one chroma coding block (which is chroma CB for short). The N nodes of the luma coding tree may or may not be limited to the additional partition. If the child luminance node continues to split, the split mode of the child luma node is analyzed to perform a recursive split. When the luma coding tree node is not further split, the luminance coding tree node corresponds to a luminance coding block (which is luminance CB for short). The chrominance transform block corresponding to the CB of the chrominance signal and the chrominance coding block have the same size, and the chrominance prediction block and the chrominance coding block have the same size.

If the inter prediction mode is used for all coding blocks in the coverage area of node A, the luminance block and chrominance block of node A are further divided into N coding tree nodes including the luminance block and the chrominance block based on the separation mode S, and the N coding tree nodes may continue to be separated or may not be separated and correspond to coding blocks including a luma block and a chrominance block.

Step 5: analyze prediction information and residual CU information obtained by splitting Node A.

The prediction information includes a prediction mode (indicating an intra prediction mode or a non-intra prediction mode), an intra prediction mode, an inter prediction mode, motion information, and the like. The motion information may include information such as prediction direction (forward, backward, or bi-directional), reference index, and motion vector.

The residual information includes a coded block flag (CBF), a transform factor, a transform type (eg, DCT-2, DST-7, DCT-8), and the like. The default conversion type may be DCT-2.

If it is limited that only intra prediction can be performed for each CU obtained by splitting node A, the parsing of the luminance prediction block CB obtained by splitting node A includes: skip_flag, merge_flag, and cu_pred_mode are set to 0, 0, and 1, respectively (that is, , none of skip_flag, merge_flag, and cu_pred_mode are present in the bitstream), or skip_flag and cu_pred_mode are set to 0 and 1, respectively, by default (that is, none of skip_flag and cu_pred_mode are present in the bitstream), and the mode information of the internal CB brightness predictions; analyzing the chroma CB prediction block obtained by splitting node A includes: analyzing the chroma CB intra prediction mode. A method for parsing a chroma CB intra prediction mode may be: (1) parsing a syntax element from a bitstream to obtain a chroma CB intra prediction mode; and (2) directly setting the CB intra chroma prediction mode to one prediction mode in the intra chroma prediction mode set, for example, one of inter-component linear model mode, chroma derived mode (DM) mode, or IBC mode.

If it is limited that only inter-prediction can be performed for each CU obtained by splitting node A, parsing the prediction mode of the CU obtained by splitting node A includes: parsing skip_flag or/and merge_flag, setting cu_pred_mode to 0 by default, and obtaining by parsing analysis of an inter prediction block such as merge index, inter dir direction, reference index, motion vector predictor index, and motion vector difference.

skip_flag is a flag representing the skip mode. When the value of skip_flag is 1, it indicates that the current CU is in skip mode; or when the value of skip_flag is 0, it indicates that no skip mode is used for the current CU. merge_flag is a flag representing the merge mode. When the value of merge_flag is 1, it indicates that the current CU is in merge mode; or when the value of merge_flag is 0, it indicates that the merge mode is not used. cu_pred_mode is a flag representing the coding block prediction mode. When the value of cu_pred_mode is 1, it indicates that intra prediction is being performed for the current prediction block; or, when the value of cu_pred_mode is 0, it indicates that the overall inter prediction is performed for the current prediction block (information such as inter prediction direction, reference index, motion vector predictor index, and motion vector difference component are identified in the bitstream).

It should be noted that in this embodiment, the intra prediction mode is a prediction mode for generating a coding block predictor using a spatial reference pixel of an image in which the coding block is located, for example, direct current mode (DC), planar mode ) or angular mode, or may include template matching mode and IBC mode.

The inter prediction mode is a prediction mode for generating a coding block predictor using a temporal reference pixel in the coding block reference picture, e.g., skip mode, merge mode, AMVP (advanced motion vector prediction) mode, general inter mode or IBC mode.

Step 6: decode each CU to obtain a reconstructed image block corresponding to node A.

For example, the predictor of each CU performs inter-prediction processing or intra-prediction processing of the CU to obtain an inter-predictive image or an intra-predictive image for the CU. Then, dequantization and inverse transform processing are performed on the transform coefficient based on the residual information of each CU to obtain a residual image, and the residual image is superimposed on the predicted image in the corresponding area to generate a reconstructed image.

According to the division mode in Embodiment 4, a large chrominance block is generated on which intra prediction is performed, thereby solving the technical problem of small block intra prediction.

Implementation Option 5

Step 1, Step 2, Step 3, and Step 6 in this embodiment are the same as in Embodiment 4.

Step 4: Determine the chroma block split mode and the luminance block split mode of node A.

The node A luminance block continues to be divided based on the division mode S to generate N nodes of the luminance coding tree. The node A chroma block is not further split and corresponds to one chroma coding block (CB chroma). The chrominance conversion block corresponding to the chroma CB and the chroma code block have the same size. [Note: Compared with Embodiment 4, in this embodiment, regardless of whether the inter prediction mode or the intra prediction mode is used, the constraint that the chrominance block is always not divided and the luma block is always divided based on the separation mode S is used regardless on the prediction mode for the coverage area of node A.]

Step 5: analyze the prediction block and the CU residual information obtained by splitting node A.

If it is limited that only intra prediction can be performed for each CU obtained by splitting Node A, the processing is the same as in Embodiment 4.

If it is limited that only inter-prediction can be performed for each CU obtained by splitting node A, parsing the luminance prediction mode CB obtained by splitting node A includes: parsing skip_flag or/and merge_flag, setting cu_pred_mode to 0 by default, and obtaining by parsing an inter prediction block such as merge index, inter dir direction, reference index, motion vector predictor index, and motion vector difference . The motion information of each 4x4 sub-block in the CB luma is output from the inter-prediction block obtained by parsing.

If it is limited that only inter-prediction can be performed for each CU obtained by splitting Node A, the chroma CB prediction block obtained by splitting Node A does not need to be parsed, and the chroma CB is divided into 2x2 chroma sub-blocks (where the split mode may be S separation). The motion information of each 2x2 chrominance subblock is the motion information of the 4x4 luma region corresponding to the 2x2 chrominance subblock.

According to the separation mode in Embodiment 5, neither a small chrominance block on which intra prediction is performed nor a transform block smaller than 16 pixels is generated. Therefore, in Embodiment 5, the above technical problems of intra prediction and coefficient coding are solved.

Embodiment 6

Step 1, step 2, step 3, step 4 and step 6 in this embodiment are the same as those in Embodiment 5.

Step 5: analyze the prediction block and the CU residual information obtained by splitting node A.

If it is limited that only intra prediction can be performed for each CU obtained by splitting Node A, the processing is the same as in Embodiment 5.

If it is limited that only inter-prediction can be performed for each CU obtained by splitting node A, the parsing of the luminance prediction block CB obtained by splitting node A is the same as in Embodiment 5.

If it is limited that only inter-prediction can be performed for each CU obtained by splitting Node A, the chrominance prediction block CB obtained by splitting Node A does not need to be parsed, the chrominance prediction block and the chrominance coding blocks have the same size, and information about The chrominance CB motion is motion information for a particular predetermined position in the luminance region corresponding to the CB color (eg, center, lower right corner, or upper left corner of the luminance region).

According to the division mode in Embodiment 6, neither the small block chroma on which intra prediction is performed, nor the small block transform block, nor the small chrominance block on which inter prediction is generated is generated.

Embodiment 7

Step 1: Step 1 is the same as Step 1 in Embodiment 4.

Step 2: determine if the luma block of at least one child block B in the child nodes obtained by splitting node A based on the partition mode S is a 4x4 luma block (whether it be width, height and/or split mode of node A and /or the width and height of node B satisfy at least one of the conditions in case 1).

If the size (ie, width and height) of node A and/or partition mode S satisfies/satisfies at least one of the conditions in case 1, it is restricted that intra prediction is performed for all coding blocks in the coverage area of node A; otherwise, it is determined whether the chrominance block of at least one child node B in the child nodes obtained by partitioning node A based on the partition mode S is a small block (regardless of whether the size and/or partition mode S of the node A and/or width and height of node B, at least one of the conditions in case 2, if yes, steps 3 to step 6 are performed.

In particular, the following two cases are considered for the method of determining that a chrominance block of at least one child Node B of Node A is a small block.

Case 1:

If one or more of the following preset conditions are met, node A is split based on split mode S to obtain a 4x4 luma block:

(1) Node A includes M1 pixels, and the split mode of Node A is quadtree split. For example, M1 is 64;

(2) Node A includes M2 pixels, and the split mode of Node A is ternary tree split. For example, M2 is 64;

(3) Node A includes M3 pixels, and Node A splitting mode is binary tree splitting. For example, M3 is 32;

(4) the width of node A is equal to four times the second threshold, the height of node A is equal to the second threshold, and the split mode of node A is a vertical split ternary tree;

(5) the width of node A is equal to the second threshold value, the height of node A is equal to four times the second threshold value, and the partitioning mode of node A is horizontal splitting of the ternary tree;

(6) the width of node A is equal to twice the second threshold, the height of node A is equal to the second threshold, and the split mode of the current node is vertical binary split;

(7) the height of node A is equal to twice the second threshold, the width of node A is equal to the second threshold, and the division mode of the current node is horizontal binary division; or

(8) the width or/and height of node A is twice the second threshold, and the split mode of node A is quadtree split.

The size may be the width and height of the image area corresponding to node A, or the number of luminance samples included in the image area corresponding to node A or the image area corresponding to node A.

Typically, the width of the current node is the width of the luminance block corresponding to the current node, and the height of the current node is the height of the luminance block corresponding to the current node. In a particular implementation, for example, the second threshold may be 4.

Case 2:

(1) the chrominance block of at least one child node B of node A has a size of 2x4 or 4x2;

(2) the width or height of the chrominance block of at least one child node B of node A is 2;

(3) node A includes 128 luma samples and ternary tree splitting is performed at node A, or node A includes 64 luma samples and binary tree splitting, quadtree splitting, or ternary tree splitting is performed at node A;

(4) node A includes 256 luma samples and ternary tree splitting or quadtree splitting is performed at the node, or node A includes 128 luma samples and binary tree splitting is performed at the node;

(5) node A includes N1 luma samples, and a ternary tree split is performed at node A, where N1 is 64, 128, or 256;

(6) node A includes N2 luma samples, and a quadtree split is performed at node A, where N2 is 64 or 256; or

(7) node A includes N3 luma samples, and a binary tree split is performed at node A, where N3 is 64, 128, or 256.

It should be noted that node A includes 128 luminance samples can also be described as that the area of the current node is 128, or the product of the width and height of node A is 128. Details are not described.

Step 3: Step 3 is the same as Step 3 in Embodiment 4.

Step 4: determine the chrominance block separation mode and the luma block separation mode of node A based on the prediction mode used for coding blocks in the coverage area of node A.

If the inter prediction mode is used for all coding blocks in the node A coverage area, the luma block and the chrominance block of node A are separated based on the separation mode S to obtain node A children and/or child nodes in the node A coverage area. If a 4x4 luma block is generated based on the split mode of the child node A and/or the child node in the coverage area of the node A, the split mode of the child node is not allowed or additional split of the child node cannot be performed. For example, if node A is generated that has a size of 8x8 and two 8x4 nodes (or two 4x8) by splitting node A in horizontal splitting binary tree mode (or vertical splitting binary tree), then the 8x4 mode (or 4x8) node continues splitting into a 4x4 block; in this case, the 8x4 (or 4x8) node cannot be further split.

If the intra prediction mode is used for all coding blocks in the coverage area of node A, the methods in Embodiments 4, 5, and 6 may be used as implementation methods, and details are not described here again. For example, node A's luma block is split and node A's chrominance block is not split.

Step 5: analyze the prediction block and the CU residual information obtained by splitting node A.

This step is the same as step 5 in Embodiment 4, and details are not described here again.

Step 6: decode each CU to obtain a reconstructed picture block signal corresponding to node A.

Step 6 may be implemented similarly to step 6 in Embodiment 4 and is not further described here.

Embodiment 8

Step 1: Step 1 is the same as Step 1 in Embodiment 4.

Step 2: determine if the luma block of at least one child block B in the child nodes obtained by splitting node A based on the partition mode S is a 4x4 luma block (whether it be width, height and/or split mode of node A and /or the width and height of node B satisfy at least one of the conditions in case 1). If the size (ie, width and height) of node A and/or partition mode S satisfies/satisfies at least one of the conditions in case 1, it is restricted that intra prediction is performed for all coding blocks in the coverage area of node A; or

it is determined whether the chrominance block of at least one child node B in the child nodes obtained by partitioning node A based on partition mode S is a small block (or size and/or partition mode S of node A, and/or width and height node B satisfy at least one of the conditions in case 2, steps 3 to step 6 are performed.

In particular, the following two cases are considered for the method of determining that a chrominance block of at least one child Node B of Node A is a small block.

Case 1:

If one or more of the following specified conditions are true, node A is split based on split mode S to obtain a 4x4 luma block:

(1) Node A includes M1 pixels, and Node A split mode is quadtree split. For example, M1 is 64;

(2) Node A includes M2 pixels, and the split mode of Node A is ternary tree split. For example, M2 is 128;

(3) Node A includes M3 pixels, and Node A splitting mode is binary tree splitting. For example, M3 is 32;

(4) the width of node A is equal to four times the second threshold, the height of node A is equal to the second threshold, and the split mode of node A is a vertical split ternary tree;

(5) the width of node A is equal to the second threshold value, the height of node A is equal to four times the second threshold value, and the partitioning mode of node A is horizontal splitting of the ternary tree;

(6) the width of node A is equal to twice the second threshold, the height of node A is equal to the second threshold, and the division mode of the current node is vertical binary division;

(7) the height of node A is equal to twice the second threshold, the width of node A is equal to the second threshold, and the division mode of the current node is horizontal binary division; or

(8) the width and/or height of node A is twice the second threshold, and the split mode of node A is quadtree split.

The size may be the width and height of the image area corresponding to node A, or the number of luminance samples included in the image area corresponding to node A or the area of the image area corresponding to the node. AND.

Typically, the width of the current node is the width of the luminance block corresponding to the current node, and the height of the current node is the height of the luminance block corresponding to the current node. In a particular implementation, for example, the second threshold may be 4.

Case 2:

(1) the chrominance block of at least one child node B of node A has a size of 2x4 or 4x2;

(2) the width or height of the chrominance block of at least one child node B of node A is 2;

(3) Node A includes 128 luma samples and node A ternary tree split is performed, or Node A includes 64 luma samples and binary tree split, quadtree split, or ternary tree split is performed at node A;

(4) Node A includes 256 luminance samples, and node A splits ternary tree or quadtree splits, or Node A includes 128 luma samples, and binary tree splits performs at node;

(5) node A includes N1 luma samples, and a ternary tree split is performed at node A, where N1 is 64, 128, or 256;

(6) node A includes N2 luma samples, and quadtree splitting is performed at node A, where N2 is 64 or 256; or

(7) node A includes N3 luma samples, and a binary tree split is performed at node A, where N3 is 64, 128, or 256.

It should be noted that node A includes 128 luminance samples can also be described as that the area of the current node is 128, or the product of the width and height of node A is 128. Details are not described.

Step 3: Step 3 is the same as Step 3 in Embodiment 4.

Step 4: determine the chrominance block separation mode and the luma block separation mode of node A based on the prediction mode used for coding blocks in the coverage area of node A.

If inter prediction mode is used for all coding blocks in the Node A coverage area, the luma block and the chrominance block of Node A are separated based on the separation mode S to obtain Node A children and/or children in the Node A coverage area. If a 4x4 luma block is generated based on the split mode of the child node A and/or the child node in the coverage area of node A, the split mode of the child node is not allowed or the child node is not further split. For example, if node A has a size of 8x8 and two 8x4 nodes (or two 4x8) are generated by splitting node A in horizontal splitting binary tree mode (or vertical splitting binary tree), then the 8x4 mode (or 4x8) node continues to split into a 4x4 block; in this case, the 8x4 (or 4x8) node cannot be split.

If intra prediction mode is used for all coding blocks in the coverage area of node A, the methods in Embodiments 4, 5, and 6 may be used as implementation methods, and details are not described here again. For example, node A's luma block is split and node A's chrominance block is not split.

Step 5: analyze the prediction block and the CU residual information obtained by splitting node A.

This step is the same as step 5 in Embodiment 4, and details are not described here again.

Step 6: decode each CU to obtain a reconstructed picture block signal corresponding to node A.

Step 6 may be implemented similarly to step 6 in Embodiment 4 and is not further described here.

Option 9 implementation

If the current area is split once to generate a 4x4 luma block (for example, 64 luma samples are split in QT mode or 128 luma samples are split in TT mode), it is only limited that the default internal mode can be used for the current region;

otherwise, a flag is passed indicating that only outer mode or only inner mode can be used for the current region.

If it is limited that only outer mode can be used for the current area, luma and chrominance are shared together. If a node in the current region is split to generate a 4x4 luma block, such splitting is not allowed. For example, if the current node is 8x8 and split in HBT (or VBT) mode to generate two 8x4 nodes. If these nodes are still split to generate 4x4 CUs, these 8x4 nodes cannot further split.

If it is restricted that only intra mode can be used for an area, this implementation is the same as the original implementation (luma is split, but chroma is not split).

This embodiment of the present invention provides a block splitting method to avoid using the intra prediction mode for a chrominance block with a relatively small area and to facilitate hardware pipelining and decoder implementation. Additionally, in inter prediction, parsing processes of syntax elements for some prediction modes can be skipped, thereby reducing coding complexity.

Thus, the technical problems of coding the coefficients are solved and the complexity of coding is reduced.

The block splitting method can be as follows:

The partitioning mode of node A is analyzed.

It is determined whether a chrominance block of at least one child node B is received as a small block after the node A is divided based on the partition mode S. (It is determined whether the width, height, and/or split mode of node A and/or the width and height of node B satisfy at least one of the above conditions.)

If it is determined that a chrominance block of at least one child node B is obtained as a small block after node A is partitioned based on the partition mode S, the intra prediction mode or the inter prediction mode is used for all coding blocks in the coverage area of node A.

Determines whether to continue separating the chroma block and the luma block of node A.

If intra prediction is performed for all coding blocks in the node A coverage area, the node A luminance block is further divided based on the separation mode S, and the node A chrominance block is not further divided. If inter-prediction is performed for all coding blocks in the coverage area of node A, the luma block and the chrominance block of node A continue to be divided based on the split mode S into N coding tree nodes including the luma block and the chrominance block.

The node A luminance block continues to be divided based on the separation mode S, and the node A chrominance block is no longer divided. The chrominance conversion block and the chroma encoding block have the same size.

When intra prediction is performed for all coding blocks in the coverage area of node A, the chrominance prediction block and the chrominance coding block have the same size; or, when inter-prediction is performed for all coding blocks in the coverage area of node A, the chrominance prediction block is divided into subblocks (where the subblocks are smaller than the chrominance coding block), and the motion vector of each subblock is the motion vector in the luminance region corresponding to the subblock.

The luminance block of node A is further divided based on the separation mode S. The node A chrominance block is not further split. The chrominance conversion block corresponding to the chrominance coding block and the chrominance coding block have the same size, the chrominance prediction block and the chrominance coding block have the same size, and the chrominance motion information CB is motion information for a specific predetermined position in the luma region corresponding to the chrominance CB.

For example, it should be understood that the disclosed content with reference to the described method may also be true for the corresponding device or system configured to perform the method, and vice versa. For example, if one or more specific method steps are described, the corresponding device may include one or more blocks, such as functional blocks, for performing the one or more method steps described (for example, one block performing one or more steps; or a plurality of blocks , each of which performs one or more of the plurality of steps) even if such one or more units are not explicitly described or illustrated in the accompanying drawings. Additionally, for example, if a particular device is described in terms of one or more blocks, such as functional blocks, the corresponding method may include one step to perform the functions of one or more blocks (for example, one step to perform the functions of one or more blocks) one or several blocks or a plurality of steps, each of which is used to perform the functions of one or more of the plurality of blocks), even if such one or more steps are not explicitly described or illustrated in the accompanying drawings. Additionally, it should be understood that features of the exemplary embodiments and/or aspects described in this specification may be combined with each other unless specifically noted otherwise.

In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored or transmitted as one or more instructions or code on a computer-readable medium and executed by a hardware processor. A computer-readable medium may include a computer-readable medium that corresponds to a tangible medium, such as a data medium, or a communication medium, including any medium that facilitates the transfer of a computer program from one place to another, for example, in accordance with a protocol. Thus, a computer-readable medium can typically correspond to (1) a non-volatile tangible computer-readable storage medium, or (2) a communication medium such as a signal or carrier wave. A storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, code, and/or data structures for implementing the technologies described in the present invention. The computer program product may include a computer readable medium.

By way of example, and not limitation, such type of computer-readable storage medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage device, magnetic disk storage device or other magnetic storage device, flash memory, or any another medium that can be used to store the desired program code in the form of instructions or data structures and that can be accessed by a computer. Additionally, any connection is appropriately referred to as a computer-readable medium. For example, if instructions are sent from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are contained in the media definition. However, it should be understood that the computer-readable storage medium and the storage medium do not include a connection, carrier wave, signal, or other temporary medium, and are in fact directed to non-volatile tangible storage media. As used in this specification, a disc and an optical disc include a compact disc (CD), a laser disc, an optical disc, a digital versatile disc (DVD), a soft disc, and a Blu-ray disc. A disc usually reproduces data magnetically, while an optical disc reproduces data optically using a laser. A combination of the above should also be included in the scope of computer readable media.

Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays, FPGA) or other equivalent integrated or discrete logic circuits. Therefore, the term "processor" as used in this specification may represent any of the above structures, or another structure that is applicable to implement the technologies described in this specification. Furthermore, in some aspects, the functionality described in this specification may be provided within dedicated hardware and/or software modules capable of encoding and decoding or contained in a combined codec. Additionally, all technologies may be implemented in one or more circuits or logic elements.

The technologies of the present invention may be implemented in a wide variety of devices or devices, including a wireless telephone, an integrated circuit (IC), or a set of ICs (eg, a chipset). The present invention describes various components, modules, or blocks to describe the functional aspects of devices capable of performing the disclosed technologies, but not necessarily requiring implementation by different hardware blocks. Exactly as described above, the blocks may be combined into a codec hardware block, or provided by a set of cooperating hardware blocks, including one or more processors, as described above, along with associated software and/or firmware.

Claims (98)

1. A method for dividing an image, comprising: determining a splitting mode of the current node, in which the current node contains a luminance block and a chrominance block; determining, based on the split mode of the current node and the size of the current node, that the chrominance block of the current node is not further split; and splitting the luminance block of the current node based on the splitting mode of the current node. 2. The method of claim 1, wherein determining that the current node's chrominance block is not further split comprises: when determining based on the splitting mode of the current node and the size of the current node that the child node generated by splitting the current node contains a chrominance block whose side length is less than a threshold value, the chrominance block of the current node is not further divided. 3. The method according to claim 1, in which when the width of the current node is two times the threshold and the splitting mode of the current node is vertical binary splitting, or when the height of the current node is two times the threshold and the splitting mode of the current node is horizontal binary splitting, or when the width of the current node is four times the threshold and the split mode of the current node is vertical triple split, or when the height of the current node is four times the threshold and the split mode of the current node is horizontal triple split, or when the width of the current node is two times the threshold value and the split mode of the current node is quadruple split, the current node's chrominance block is not further split. 4. The method according to any one of paragraphs. 1-3, wherein the luminance block of the current node is split based on the splitting mode of the current node to obtain child nodes of the current node, wherein each child node contains only the luminance block. 5. The method of claim 4, wherein the method further comprises: parsing the luminance block information of the current node to obtain prediction information and residual information of each of the sub-regions in the luminance block, in which the sub-regions one-to-one correspond to child nodes. 6. The method according to claim 4 or 5, wherein the child nodes are further not split by default and each child node corresponds to one coding block containing only a luma block. 7. The method according to any one of paragraphs. 1-6, wherein the method further comprises: when the chrominance block of the current node is not further divided, obtaining the chrominance block prediction mode. 8. The method of claim 7, wherein the chrominance block prediction mode of the current node is determined based on the luminance block prediction mode at a given position of the current node. 9. The method of claim 8, wherein when the prediction mode used for the luminance block at the given position is an inter prediction mode, the inter prediction mode is used for the chrominance block of the current node; or the first flag is parsed to determine a chrominance block prediction mode based on the first flag. 10. The method of claim 9, wherein when the inter prediction mode is used for a chrominance block of the current node, information about the movement of the luminance block at a given position is obtained as information about the movement of the chrominance block; or the chrominance block is divided into chrominance prediction sub-blocks, and motion information of the chrominance prediction sub-blocks is obtained. 11. The method of claim 9, wherein when it is determined, based on the first flag, that the intra prediction mode is used for the chrominance block, the intra prediction mode is parsed from the bitstream and used as the intra prediction mode of the chrominance block; when, based on the first flag, it is determined that the inter prediction mode is used for the chrominance block, motion information of the luma block at a given position is obtained as motion information of the chrominance block; or when, based on the first flag, it is determined that the inter prediction mode is used for a chrominance block, the chrominance block is divided into chrominance prediction subblocks, and movement information of the chrominance prediction subblocks is obtained. 12. The method according to claim 10 or 11, wherein the motion information of the chrominance prediction sub-blocks is obtained, comprising: if inter-prediction is performed for luma blocks at luma image positions corresponding to chrominance prediction subblocks, motion information at luminance image positions corresponding to chrominance prediction subblocks is used as motion information of chrominance prediction subblocks; otherwise, the motion information at the given position is used as the motion information of the chrominance prediction sub-blocks. 13. The method of claim 8, wherein when the prediction mode used for the luma block at the given position is the intra prediction mode, the intra prediction mode is used for the chrominance block of the current node. 14. The method of claim 13, wherein the intra prediction mode is parsed from the bitstream as the intra prediction mode of the current node's chrominance block; or the chrominance block intra prediction mode of the current node is one of: constant mode, planar mode, angular mode, cross-component linear model mode, or derived DM chroma mode. 15. The method of claim 8, wherein when the prediction mode used for the luminance block at the given position is the intra block copy mode, IBC, IBC prediction mode is used for the current node's chrominance block; or the second flag is parsed to determine a chrominance block prediction mode based on the second flag. 16. The method of claim 15, wherein when the IBC prediction mode is used for a chrominance block of the current node, the method further comprises: obtaining the offset vector information of the luminance block at a given position as the offset vector information of the chrominance block of the current node. 17. The method of claim 15, wherein the IBC mode is used for the chroma block if the value of the second flag is the first value; the intra prediction mode is used for the chrominance block if the value of the second flag is the first value; or the inter prediction mode is used for the chrominance block if the value of the second flag is the second value. 18. The method of claim 7, wherein the method further comprises: obtaining a prediction mode of a plurality of luminance blocks obtained by division; and determining a chrominance block prediction mode of the current node based on the prediction mode of the plurality of luma blocks obtained by splitting. 19. The method of claim 18, wherein when the prediction mode used for the plurality of luma blocks is an intra prediction mode, the intra prediction mode is used for the chrominance block of the current node. 20. The method of claim 18, wherein when the prediction mode used for the plurality of luma blocks is an inter prediction mode, the motion information of the luminance block at a given position is used as the motion information of the chrominance block of the current node when the inter prediction mode is used. for the chrominance block of the current node; or when the prediction mode used for the plurality of luminance blocks is the inter prediction mode, the first flag is analyzed to determine the chrominance block prediction mode based on the first flag. 21. The method of claim 20, wherein when it is determined, based on the first flag, that an intra prediction mode is used for the chrominance block, the intra prediction mode is parsed from the bitstream and used as the intra prediction mode for the chrominance block; or when, based on the first flag, it is determined that the inter prediction mode is used for a chrominance block, motion information of the luma block at a given position is obtained as motion information of the chrominance block. 22. The method of claim 18, wherein when the prediction mode used for the plurality of luminance blocks comprises an inter prediction mode and an intra prediction mode, the luminance block prediction mode at a given position of the current node is obtained as the chrominance block prediction mode of the current node. 23. The method according to any one of paragraphs. 1-22, in which, if the current node is an I-frame, the intra prediction mode is used for each child node of the current node; or, if the current node is a P-frame or a B-frame, the first child node is parsed to obtain the prediction mode of the first child node, in which the prediction mode of the remaining child nodes is the same as the prediction mode for the first child node, and the first child node is the node that is parsed first. 24. The method according to any one of paragraphs. 1-22, in which, if the current node is an I-frame, the intra prediction mode is used for each child node of the current node; or, if the current node is a P-frame or a B-frame, the inter prediction mode is used for each child node of the current node. 25. The method according to any one of paragraphs. 1-24, wherein determining, based on the splitting mode of the current node, the size of the current node, and the prediction mode of the first child node of the current node, that the chrominance block of the current node is not further divided, in which the first child node contains only the luma block, and the first child node is the node that is parsed first. 26. The method of claim 25, wherein, based on the split mode of the current node and the size of the current node, it is determined that the child node generated by splitting the current node contains a chrominance block whose side length is less than a threshold value and the prediction mode of the first child node is mode of intra prediction, the chrominance block of the current node is not further divided. 27. The method of claim 26, wherein when the prediction mode of the first child node is intra prediction, and any of the following conditions are met: when the width of the current node is twice the threshold and the splitting mode of the current node is vertical binary splitting, or when the height of the current node is twice the threshold value and the splitting mode of the current node is horizontal binary splitting, or when the width of the current node is four times the threshold and the split mode of the current node is vertical triple split, or when the height of the current node is four times the threshold and the split mode of the current node is horizontal triple split, or when the width of the current node is twice the threshold value and the split mode of the current node is quadruple split, the current node's chrominance block is not further split. 28. The method according to any one of paragraphs. 1-24, in which, based on the division mode of the current node and the size of the current node, it is determined that the child node generated by the division of the current node contains a chrominance block whose side length is less than a threshold value; if the prediction mode of the first child node is inter-prediction, the chrominance block of the current node is divided based on the split mode of the current node, in which the first child node is the node that is parsed first. 29. The method of claim 28, wherein the method further comprises: determining motion information of a corresponding child node of the chrominance block based on the motion information of the child nodes of the current node. 30. The method according to any one of paragraphs. 1-24, wherein, when it is determined based on the splitting mode of the current node and the size of the current node that the child node generated by splitting the current node contains a chroma block whose width is less than a threshold value, the chroma block of the current node is not further divided. 31. The method according to any one of paragraphs. 1-24, wherein when it is determined, based on the splitting mode of the current node and the size of the current node, that the child node generated by splitting the current node contains a chroma block whose number of chroma samples is less than 16, the chroma block of the current node is not further divided. 32. The method according to claim 31, in which when the product of the current node's width and height is less than 128 and the current node's split mode is vertical binary split or horizontal binary split, or when the product of the current node's width and height is less than 256 and the current node's split mode is vertical tri-split, horizontal tri-split, or quadruple split, or when the product of the current node's width and height is 64 and the current node's split mode is vertical binary split, horizontal binary split, quadruple split, horizontal triple split, or vertical triple split, or when the product of the width and height of the current node is 128 and the split mode of the current node is vertical triple split or horizontal triple split, the current node's chrominance block is not further split. 33. The method according to paragraphs. 2, 3, 26, 27, 28, or 30 where the threshold is 4. 34. The method according to any one of paragraphs. 1-33, wherein the split mode of the current node comprises at least one of: quadruple split (QT), horizontal binary split (horizontal BT), horizontal ternary split (horizontal TT), vertical binary split (Vertical BT), and vertical triple separation (Vertical TT). 35. The method of claim 1, wherein when the product of the width and height of the current node is 64 and the split mode of the current node is quadtree split or ternary tree split, or when the product of the width and height of the current node is 32 and the splitting mode of the current node is binary tree splitting, the current node's chrominance block is not further split. 36. The method according to p. 1, in which the current node belongs to the I-segment; when the product of the current node's width and height is 64 and the current node's split mode is a binary tree split, or when the product of the width and height of the current node is 128 and the split mode of the current node is ternary tree split, the current node's chrominance block is not further split. 37. The method according to any one of paragraphs. 1-36, in which the need to split the chrominance block of the current node is determined based on the split mode of the current node, the size of the current node, and the ID (cons_pred_mode_flag) of the prediction mode of the node. 38. The method of claim 37, wherein the current node belongs to a P or B segment; when the product of the width and height of the current node is 64 and the split mode of the current node is binary tree split, or the product of the width and height of the current node is 128 and the split mode of the current node is ternary tree split, and when the node prediction mode identifier indicates that inter-prediction is not performed on the coding block obtained by dividing the current node, the current node's chrominance block is not further split. 39. The method according to any one of paragraphs. 1-38, in which, based on the data format of the current node, the division mode of the current node, and the size of the current node, it is determined whether to further divide the chrominance block of the current node. 40. The method of claim 39, wherein the data format of the current node is YUV4:2:0 or YUV4:2:2. 41. The method of claim 39, wherein intra prediction or inter prediction is performed on all coding blocks in the coverage area of the current node. 42. A device for decoding a video stream, comprising a processor and a memory, in which the memory stores an instruction, and this instruction allows the processor to perform the method according to any one of paragraphs. 1-41. 43. A device for encoding a video stream, containing a processor and memory, in which the memory stores an instruction, and this instruction allows the processor to perform the method according to any one of paragraphs. 1-41. 44. A device for decoding, containing a read-only memory and a processor that are connected to each other, in which the memory is configured to store a program instruction, and the program instruction allows the processor to perform the method according to any one of paragraphs. 1-41. 45. A device for encoding, containing a read-only memory and a processor that are connected to each other, in which the memory is configured to store a program instruction, and the program instruction allows the processor to perform the method according to any one of paragraphs. 1-41.

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