Prediction model acquisition method and device

Abstract

The present disclosure relates to a method and device for obtaining a luma intra-frame prediction mode. The method comprises the following steps: obtaining a content identifier of a luma prediction block of a current coding unit; and obtaining a luma intra-frame prediction mode of the luma prediction block according to the obtained content identifier.

Description

Technical Field

[0001] The present invention relates to the technical field of video coding and decoding, and in particular to a method and device for obtaining a prediction mode in video coding and decoding. Background Art

[0002] In video decoding, it is necessary to divide the image into the largest decoding unit and the basic block. Figure 1a As shown in , the image is divided into a series of maximum decoding units, and each maximum decoding unit is decoded in sequence according to the raster scanning order within the slice. Figure 1b As shown in the figure, the maximum decoding unit adopts the basic block division structure of QT+BT+EQT. QT (quadtree structure) divides one decoding unit into four sub-decoding units, and BT (binary tree structure) can divide one decoding unit into two sub-decoding units: left and right / upper and lower. EQT (extended quadtree structure) includes two I-shaped division methods, horizontal and vertical, which divides one decoding unit into 4 sub-decoding units.

[0003] A prediction unit consists of a luma prediction block and a corresponding chroma prediction block, and is divided by a decoding unit. If the decoding unit type of the decoding unit is 'I_2M_2N', 'I_2M_hN', 'I_2M_nU', 'I_2M_nD', 'I_hM_2N', 'I_nL_2N', or 'I_nR_2N', its prediction type is normal intra prediction, and the prediction type of the prediction block it contains is normal intra prediction; otherwise, if the decoding unit type is 'IBC_2M_2N', its prediction type is block copy intra prediction, and the prediction type of the prediction block it contains is block copy intra prediction; otherwise, the prediction type of the decoding unit is inter prediction, and the prediction type of the prediction unit and prediction block it contains is inter prediction. Summary of the Invention

[0004] One aspect of the present invention provides a prediction mode acquisition method for a video decoder, comprising: obtaining a content identifier of a luminance prediction block of a current coding unit; and obtaining a luminance intra-frame prediction mode of the luminance prediction block according to the obtained content identifier.

[0005] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining the luminance intra-frame prediction mode of a luminance prediction block according to an obtained content identifier includes: obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier, deriving a first intra-frame prediction mode and a second intra-frame prediction mode based on the obtained intra-frame prediction mode A and intra-frame prediction mode B, and deriving the luminance intra-frame prediction mode of the luminance prediction block based on the intra-frame luminance prediction mode of the luminance prediction block and the first intra-frame prediction mode and the second intra-frame prediction mode.

[0006] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining the luminance intra-frame prediction mode of a luminance prediction block according to an obtained content identifier includes: obtaining intra-frame prediction mode A and intra-frame prediction mode B, deriving a first intra-frame prediction mode and a second intra-frame prediction mode based on the obtained intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier, and deriving the luminance intra-frame prediction mode of the luminance prediction block based on the intra-frame luminance prediction mode of the luminance prediction block and the first intra-frame prediction mode and the second intra-frame prediction mode.

[0007] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining the luminance intra-frame prediction mode of a luminance prediction block according to an obtained content identifier includes: obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier, deriving a first intra-frame prediction mode and a second intra-frame prediction mode based on the obtained intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier, and deriving the luminance intra-frame prediction mode of the luminance prediction block based on the intra-frame luminance prediction mode of the luminance prediction block and the first intra-frame prediction mode and the second intra-frame prediction mode.

[0008] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining intra-frame prediction mode A and intra-frame prediction mode B according to an obtained content identifier includes: when prediction block A and prediction block B exist and the condition of being a normal intra-frame prediction mode does not hold, the values ​​of intra-frame prediction mode A and intra-frame prediction mode B are different according to the obtained content identifier.

[0009] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier includes: when the obtained content identifier is a first content identifier, if the prediction block A exists and is in a normal intra-frame prediction mode, the intra-frame prediction mode of the prediction block A is assigned to the intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to a first predetermined value; if the prediction block B exists and is in a normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to the intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to the first predetermined value; when the obtained content identifier is a second content identifier, if the prediction block A exists and is in a normal intra-frame prediction mode, the intra-frame prediction mode of the prediction block A is assigned to the intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to the second predetermined value; if the prediction block B exists and is in a normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to the intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to the second predetermined value.

[0010] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining intra-frame prediction mode A and intra-frame prediction mode B according to an obtained content identifier includes: when the obtained content identifier is a first content identifier, if the prediction block A exists and is in a normal intra-frame prediction mode and the content identifier of the coding unit where the prediction block A is located is the first content identifier, then the intra-frame prediction mode of the prediction block A is assigned to the intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to a first predetermined value; if the prediction block B exists and is in a normal intra-frame prediction mode and the coding unit where the prediction block B is located is the first content identifier, then the intra-frame prediction mode of B is assigned to the intra-frame prediction mode A. mode is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to the first predetermined value; when the obtained content identifier is the second content identifier, if the prediction block A exists and is in the normal intra-frame prediction mode and the content identifier of the coding unit where the prediction block A is located is the second content identifier, then the intra-frame prediction mode of the prediction block A is assigned to the intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to the second predetermined value; if the prediction block B exists and is in the normal intra-frame prediction mode and the coding unit where the prediction block B is located is the second content identifier, then the intra-frame prediction mode of B is assigned to the intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to the second predetermined value.

[0011] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining intra-frame prediction mode A and intra-frame prediction mode B according to an obtained content identifier includes: when the obtained content identifier is a first content identifier, if the prediction block A exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of the prediction block A to the intra-frame prediction mode A; otherwise, assigning the intra-frame prediction mode A to a first predetermined value; if the prediction block B exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of the prediction block B to the intra-frame prediction mode B; otherwise, assigning the intra-frame prediction mode B to the first predetermined value; when the obtained content identifier is a second content identifier, if the prediction block A exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of the prediction block B to the intra-frame prediction mode B; otherwise, assigning the intra-frame prediction mode B to the first predetermined value. The intra-frame prediction mode of prediction block A is assigned to intra-frame prediction mode A; if prediction block A exists and is a block copy intra-frame prediction mode, and the reference block pointed to by prediction block A is a normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by prediction block A is assigned to intra-frame prediction mode A; otherwise, intra-frame prediction mode A is assigned to a second predetermined value; if prediction block B exists and is a normal intra-frame prediction mode, the intra-frame prediction mode of prediction block B is assigned to intra-frame prediction mode B; if prediction block B exists and is a block copy intra-frame prediction mode, and the reference block pointed to by prediction block B is a normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by prediction block B is assigned to intra-frame prediction mode B; otherwise, intra-frame prediction mode B is assigned to the second predetermined value.

[0012] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining intra-frame prediction mode A and intra-frame prediction mode B according to an obtained content identifier includes: when the obtained content identifier is a first content identifier, if the prediction block A exists and is in a normal intra-frame prediction mode, the intra-frame prediction mode of the prediction block A is assigned to the intra-frame prediction mode A; otherwise, the intra-frame prediction mode A is assigned to a first predetermined value; if the prediction block B exists and is in a normal intra-frame prediction mode, the intra-frame prediction mode of the prediction block B is assigned to the intra-frame prediction mode B; otherwise, the intra-frame prediction mode B is assigned to the first predetermined value; when the obtained content identifier is a second content identifier, if the prediction block A exists and is in a normal intra-frame prediction mode, the intra-frame prediction mode of the prediction block A is assigned to the intra-frame prediction mode A; if the prediction block A exists and is in a block copy intra-frame prediction mode, and the reference block pointed to by the prediction block A is in a normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by the prediction block A is assigned to the intra-frame prediction mode A; if the prediction block A exists and is in a normal intra-frame prediction mode In the block copy intra prediction mode, if the reference block pointed to by the prediction block A is not in the ordinary intra prediction mode, but the adjacent block of the reference block pointed to by the prediction block A is in the ordinary intra prediction mode, the intra prediction mode of the adjacent block of the reference block pointed to by the prediction block A is assigned to the intra prediction mode A; otherwise, the intra prediction mode A is assigned to the second predetermined value; if the prediction block B exists and is in the ordinary intra prediction mode, the intra prediction mode of the prediction block B is assigned to the intra prediction mode B; if the prediction block B exists and is in the block copy intra prediction mode , and the reference block pointed to by prediction block B is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by prediction block B is assigned to intra-frame prediction mode B; if prediction block B exists and is in block copy intra-frame prediction mode, and the reference block pointed to by prediction block B is not in normal intra-frame prediction mode, but the adjacent block of the reference block pointed to by prediction block B is in normal intra-frame prediction mode, then the intra-frame prediction mode of the adjacent block of the reference block pointed to by prediction block B is assigned to intra-frame prediction mode B; otherwise, the intra-frame prediction mode B is assigned to a second predetermined value.

[0013] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein, according to the obtained content identifier, deriving the first intra-frame prediction mode and the second intra-frame prediction mode based on the obtained intra-frame prediction mode A and the intra-frame prediction mode B includes: in the case where the obtained content identifier is the first content identifier, if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the first predetermined value, then assigning the intra-frame prediction mode B to the second predetermined value; if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is not equal to the first predetermined value, then assigning the intra-frame prediction mode A to the first predetermined value; assigning the intra-frame prediction mode B to the second predetermined value; The smaller of mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger one is assigned to the second intra-frame prediction mode. When the obtained content identifier is the second content identifier, if intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is equal to the third predetermined value, then intra-frame prediction mode B is assigned to the fourth predetermined value. If intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is not equal to the third predetermined value, then intra-frame prediction mode A is assigned to the third predetermined value. The smaller of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger one is assigned to the second intra-frame prediction mode.

[0014] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein, according to the obtained content identifier, deriving the first intra-frame prediction mode and the second intra-frame prediction mode based on the obtained intra-frame prediction mode A and the intra-frame prediction mode B includes: when the obtained content identifier is the first content identifier, if the intra-frame prediction mode A is not equal to the intra-frame prediction mode B, assigning the smaller value of the intra-frame prediction mode A and the intra-frame prediction mode B to the first intra-frame prediction mode and the larger value to the second intra-frame prediction mode; if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode B is equal to the intra-frame prediction mode B, the first intra-frame prediction mode and the second intra-frame prediction mode are derived. Formula A is equal to the first predetermined value, then the first high frequency mode in the intra mode frequency table is assigned to the first intra prediction mode, and the second high frequency mode in the intra mode frequency table is assigned to the second intra prediction mode. If intra prediction mode A is equal to intra prediction mode B, and intra prediction mode A is not equal to the first predetermined value, if the first high frequency mode in the intra mode frequency table is not equal to intra prediction mode A, then the smaller of the first high frequency mode and intra prediction mode A in the intra mode frequency table is assigned to the first intra prediction mode, and the larger one is assigned to the second intra prediction mode. Otherwise, the second high frequency mode in the intra mode frequency table is assigned to the second intra prediction mode. The smaller of the intra-frame prediction mode A and the intra-frame prediction mode A is assigned to the first intra-frame prediction mode, and the larger one is assigned to the second intra-frame prediction mode. When the obtained content identifier is the second content identifier, if the intra-frame prediction mode A is not equal to the intra-frame prediction mode B, the smaller of the intra-frame prediction mode A and the intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger one is assigned to the second intra-frame prediction mode. If the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the second predetermined value, the first high-frequency mode in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the intra-frame mode B is assigned to the second intra-frame prediction mode. The second high frequency mode in the intra mode frequency table is assigned to the second intra prediction mode; if intra prediction mode A is equal to intra prediction mode B, and intra prediction mode A is not equal to the second predetermined value, if the first high frequency mode in the intra mode frequency table is not equal to intra prediction mode A, then the smaller value of the first high frequency mode and intra prediction mode A in the intra mode frequency table is assigned to the first intra prediction mode, and the larger value is assigned to the second intra prediction mode; otherwise, the smaller value of the second high frequency mode and intra prediction mode A in the intra mode frequency table is assigned to the first intra prediction mode, and the larger value is assigned to the second intra prediction mode.

[0015] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein the content identifier is a frame-level identifier or a coding unit-level identifier.

[0016] Another aspect of the present invention provides a method for obtaining a prediction mode of a video decoder, wherein the content identifier is obtained by parsing a bit stream or the content identifier is derived at the video decoder.

[0017] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, further comprising: deriving a content type of a current coding unit according to a content identifier and related coding unit size information.

[0018] Another aspect of the present invention provides a video decoder of a prediction mode acquisition method, comprising: a content identification acquisition module, which is configured to obtain the content identification of the luminance prediction block of the current coding unit; and a prediction mode acquisition module, which is configured to obtain the luminance intra-frame prediction mode of the luminance prediction block based on the obtained content identification.

[0019] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, comprising: acquiring information of an intra-frame mode frequency table; and obtaining a luminance intra-frame prediction mode of a luminance prediction block according to the information of the intra-frame mode frequency table.

[0020] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining the luminance intra-frame prediction mode of a luminance prediction block according to information in an intra-frame mode frequency table includes: obtaining intra-frame prediction mode A and intra-frame prediction mode B according to information in the intra-frame mode frequency table; deriving a first intra-frame prediction mode and a second intra-frame prediction mode according to the obtained intra-frame prediction mode A and intra-frame prediction mode B; and deriving the luminance intra-frame prediction mode of the luminance prediction block according to the intra-frame luminance prediction mode of the luminance prediction block and the first intra-frame prediction mode and the second intra-frame prediction mode.

[0021] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein intra-frame prediction mode A and intra-frame prediction mode B are obtained according to information in an intra-frame mode frequency table: if the value of the frequency intra-frame mode encoding enable flag is 1, intra-frame prediction mode A and intra-frame prediction mode B are obtained according to the adjacent prediction units of the current luminance prediction block and the information in the intra-frame mode frequency table; if the value of the frequency intra-frame mode encoding enable flag is 0, intra-frame prediction mode A and intra-frame prediction mode B are obtained according to the information of the adjacent prediction units of the current luminance prediction block.

[0022] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein obtaining intra-frame prediction mode A and intra-frame prediction mode B according to information in an intra-frame mode frequency table includes: if prediction block A exists and is a normal intra-frame prediction mode, then the intra-frame prediction mode of prediction block A is assigned to intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to the first high-frequency mode in the intra-frame mode frequency table; if prediction block B exists and is a normal intra-frame prediction mode, then the intra-frame prediction mode of B is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to one of the first and second high-frequency modes in the intra-frame mode frequency table that is not equal to the intra-frame prediction mode A.

[0023] Another aspect of the present invention provides a prediction mode acquisition method for a video decoder, wherein, based on the obtained intra-frame prediction mode A and intra-frame prediction mode B, deriving the first intra-frame prediction mode and the second intra-frame prediction mode includes: if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the first predetermined value, then the intra-frame prediction mode A is assigned to the first predetermined value, and the intra-frame prediction mode B is assigned to the second predetermined value; if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is not equal to the first predetermined value, then the intra-frame prediction mode A is assigned to the predetermined value; the smaller of the intra-frame prediction mode A and the intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode.

[0024] Another aspect of the present invention provides a video decoder that performs a prediction mode acquisition method, including: an intra-frame mode frequency table acquisition module, which is configured to obtain information of an intra-frame mode frequency table; and a prediction mode acquisition module, which is configured to obtain a luminance intra-frame prediction mode of a luminance prediction block based on the information of the intra-frame mode frequency table.

[0025] Another aspect of the present invention provides a method for obtaining a luminance intra-frame prediction mode of a video decoder, wherein the content identifier is derived at the video decoder, including: obtaining adjacent prediction unit information of the current coding unit, and deriving the content identifier of the current coding unit based on the adjacent prediction unit information of the current coding unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals represent like parts:

[0027] Figure 1a and Figure 1b A schematic diagram showing a structure of image partitioning into a maximum decoding unit and a basic block partitioning structure;

[0028] Figure 2 A schematic diagram showing a prediction block structure is shown;

[0029] Figure 3 A schematic diagram showing a block copy intra prediction technique;

[0030] Figure 4a and Figure 4b A flowchart of an intra-frame prediction method of a video decoder according to an embodiment of the present invention is shown;

[0031] Figure 5a and Figure 5b A flowchart of an intra-frame prediction method of a video decoder according to an embodiment of the present invention is shown;

[0032] Figure 6A flow chart showing a method for encoding content identification of image content types at the encoding end;

[0033] Figure 7 A flowchart showing a method for decoding image content types at a decoding end is shown;

[0034] Figure 8 A flow chart showing a method for encoding content identification of a content type of an encoding unit at an encoding end;

[0035] Figure 9 A flowchart showing a method for decoding content types of encoding units at a decoding end is shown;

[0036] Figure 10 A flow chart showing a method for deriving a content type of a decoding-side encoding unit content type;

[0037] Figure 11 A block diagram showing a video decoder that performs an intra-frame prediction method; and

[0038] Figure 12 A block diagram of a video decoder performing an intra prediction method is shown. DETAILED DESCRIPTION

[0039] Before proceeding with the detailed description below, it may be helpful to set forth the definitions of certain words and phrases used throughout this patent document. The term "coupled" and its derivatives refer to any direct or indirect communication between two or more elements, regardless of whether those elements are in physical contact with each other. The terms "transmit," "receive," and "communicate," and their derivatives, encompass both direct and indirect communication. The terms "include," "comprise," and their derivatives, mean including, but not limited to. The term "or" is inclusive, meaning and / or. The phrase "associated with..." and its derivatives mean including, included within, interconnected, containing, contained within, connected or connected with, coupled or coupled with, communicate with, cooperate with, intertwine, juxtapose, approach, bound or bound with, have, have an attribute of, have a relationship with, or have a relationship with, etc. The term "controller" refers to any device, system, or portion thereof that controls at least one operation. Such a controller may be implemented using hardware, or a combination of hardware and software and / or firmware. The functionality associated with any particular controller may be centralized or distributed, whether local or remote. The phrase "at least one of," when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one of the items in the list may be needed. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A, B, and C.

[0040] Definitions for other specific words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior and future uses of such defined words and phrases.

[0041] Figures 1 to 2 discussed below Figure 10 The various embodiments used to describe the principles of the present disclosure in this patent document are merely exemplary and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any suitably arranged system or device.

[0042] The ordinary intra-frame prediction mode is to use the correlation of the video spatial domain to predict the pixels of the current prediction block using the encoded pixels of the current image, so as to achieve the purpose of removing the redundancy of the video spatial domain.

[0043] The AVS3 standard currently provides 65 common intra-frame prediction modes for luma prediction blocks (see Table 1). However, encoding the prediction mode for each prediction block independently introduces unnecessary redundancy. Leveraging the correlation between adjacent blocks or using the frequency of prediction modes in coded prediction blocks to create a candidate list of prediction values ​​for the prediction mode can improve coding efficiency.

[0044] Table 1 Intra-frame prediction mode of luma prediction block

[0045]

[0046]

[0047] against Figure 2 The prediction block structure shown in FIG, the steps of determining the prediction value of the prediction mode of each luma prediction block in the coding unit are as follows:

[0048] 1) If the value of the frequency intra mode coding enable flag is 1, the prediction value of the current luma prediction block prediction mode is calculated as follows:

[0049] Assign the first high-frequency mode in the intra mode frequency table to the first intra prediction mode;

[0050] The second most frequent mode in the intra mode frequency table is assigned to the second intra prediction mode.

[0051] 2) If the value of the frequency intra mode coding enable flag is 0, the prediction value of the current luma prediction block prediction mode is calculated as follows:

[0052] If the prediction block A on the left "exists" and is in normal intra prediction mode, then the intra prediction mode of A is assigned to intra prediction mode A; otherwise, the intra prediction mode A is assigned to 0;

[0053] If the prediction block B exists and is in normal intra prediction mode, then the intra prediction mode of B is assigned to intra prediction mode B; otherwise, the intra prediction mode B is assigned to 0.

[0054] If intra-frame prediction mode A is not equal to intra-frame prediction mode B, the smaller of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode. If intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is equal to 0, the first intra-frame prediction mode is assigned a value of 0, and the second intra-frame prediction mode is assigned a value of 2. If intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is not equal to 0, the first intra-frame prediction mode is assigned a value of 0, and the second intra-frame prediction mode is assigned to intra-frame prediction mode A.

[0055] Screen content refers to images captured directly from the image display unit of a computer or mobile device. Examples include computer graphics, text images, images that combine natural images with text and graphics, and computer-generated animated images. These types of screen content images are common in applications such as desktop collaboration, desktop sharing, and cloud gaming. The main difference between screen content images and natural images captured with a camera is that screen content images are noise-free, have discrete tones, and sharp edges, while natural images are typically noisy, have continuous tones, and have complex textures.

[0056] For screen content sequences, there are many repeated textures in the same frame, that is, there is a strong spatial correlation. If the area of ​​the current frame that has been encoded can be referenced when encoding the current block, the encoding efficiency can be greatly improved. Given the strong spatial correlation of screen images, this technology of referencing the encoded blocks of the current frame and using them for the prediction value of the current block is called intra block copy (IBC). Figure 3 As shown in Figure 2, block copy intra prediction is similar to inter-frame image prediction, except that the prediction block of block copy intra prediction is generated by the reconstructed block of the current coded image frame.

[0057] In the prior art, when calculating the prediction value for the prediction mode of a luma prediction block, if the prediction block to the left or above does not exist or is not in a normal intra-frame prediction mode, this can lead to the following problems: the prediction value is assigned to 0, failing to adapt to the image content; and only the normal intra-frame prediction mode is considered, ignoring the block copy intra-frame prediction mode. These problems can lead to reduced coding efficiency.

[0058] Figure 4a A flowchart of an intra-frame prediction method of a video decoder according to an embodiment of the present invention is shown. Figure 4a The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 4aThe embodiments shown are subject to adaptations and modifications.

[0059] refer to Figure 4a At step 401a, it is determined that the luminance prediction block of the current coding unit is in a normal intra-frame prediction mode, and the intra-frame luminance prediction mode of the luminance prediction block is obtained.

[0060] At step 402a, the content identifier of the luminance prediction block of the current coding unit is obtained. If the content identifier is 0, the current coding unit is natural content. If the content identifier is 1, the current coding unit is non-natural content (e.g., screen content). It should be noted that in this embodiment, the coding unit content is divided into natural content and screen content, and other content classifications can also be used, which is not limited here. In this embodiment, there are two types of content, or more than two types of content. When there are more than two types of content, the content identifier is 0, 1, ..., N, which is not limited here.

[0061] At step 403a, the luma intra prediction mode of the luma prediction block is obtained according to the obtained content identifier of the luma prediction block of the current coding unit.

[0062] (I) According to an embodiment of the present invention, if the content of the luma prediction block of the current coding unit is identified as natural content, the luma intra prediction mode of the luma prediction block is obtained as follows:

[0063] (1) Obtain intra-frame prediction mode A and intra-frame prediction mode B based on the information of the adjacent prediction blocks of the current luminance prediction block.

[0064] In one embodiment, if the left prediction block A "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of A is assigned to intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to 0; if the upper prediction block B "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to 0.

[0065] In another embodiment, if the left prediction block A "exists" and is in a normal intra-frame prediction mode and the content of the coding unit where A is located is identified as natural content, then the intra-frame prediction mode of A is assigned to intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to 0; if the upper prediction block B "exists" and is in a normal intra-frame prediction mode and the content of the coding unit where B is located is identified as natural content, then the intra-frame prediction mode of B is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to 0.

[0066] In another embodiment, if the left prediction block A "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of A is assigned to intra-frame prediction mode A; if the left prediction block A "exists" and is in block copy intra-frame prediction mode, and the reference block pointed to by A is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by A is assigned to intra-frame prediction mode A; otherwise, the intra-frame prediction mode A is assigned to 0. If the upper prediction block B "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to intra-frame prediction mode B; if the upper prediction block B "exists" and is in block copy intra-frame prediction mode, and the reference block pointed to by B is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by B is assigned to intra-frame prediction mode B; otherwise, the intra-frame prediction mode B is assigned to 0.

[0067] In another embodiment, if the left prediction block A "exists" and is in the normal intra-frame prediction mode, the intra-frame prediction mode of A is assigned to the intra-frame prediction mode A; if the left prediction block A "exists" and is in the block copy intra-frame prediction mode, and the reference block pointed to by A is in the normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by A is assigned to the intra-frame prediction mode A; if the left prediction block A "exists" and is in the block copy intra-frame prediction mode, and the reference block pointed to by A is not the normal intra-frame prediction mode, but the adjacent block of the reference block pointed to by A is the normal intra-frame prediction mode, then the intra-frame prediction mode of the adjacent block of the reference block pointed to by A is assigned to the intra-frame prediction mode A; otherwise, the intra-frame prediction mode A is assigned to 0. If the upper prediction block B "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to intra-frame prediction mode B; if the upper prediction block B "exists" and is in block copy intra-frame prediction mode, and the reference block pointed to by B is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by B is assigned to intra-frame prediction mode B; if the upper prediction block B "exists" and is in block copy intra-frame prediction mode, and the reference block pointed to by B is not in normal intra-frame prediction mode, but the adjacent block of the reference block pointed to by B is in normal intra-frame prediction mode, the intra-frame prediction mode of the adjacent block of the reference block pointed to by B is assigned to intra-frame prediction mode B; otherwise, the intra-frame prediction mode B is assigned to 0.

[0068] The performance of video coding is improved by adaptively assigning values ​​according to image content and considering block copy intra prediction mode.

[0069] (2) The first intra prediction mode and the second intra prediction mode are derived according to the obtained intra prediction mode A and intra prediction mode B.

[0070] In one embodiment, if intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is equal to 0, then intra-frame prediction mode A is assigned a value of 0 and intra-frame prediction mode B is assigned a value of 2. If intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is not equal to 0, then intra-frame prediction mode A is assigned a value of 0. The smaller of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode. The values ​​assigned in this embodiment are 0 and 2, but other values ​​may also be used and are not limited here.

[0071] In another embodiment, if intra-frame prediction mode A is not equal to intra-frame prediction mode B, the smaller of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger is assigned to the second intra-frame prediction mode. If intra-frame prediction mode A is equal to intra-frame prediction mode B and intra-frame prediction mode A is equal to 0, the first high-frequency mode in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the second high-frequency mode in the intra-frame mode frequency table is assigned to the second intra-frame prediction mode. If intra-frame prediction mode A is equal to intra-frame prediction mode B and intra-frame prediction mode A is not equal to 0, if the first high-frequency mode in the intra-frame mode frequency table is not equal to intra-frame prediction mode A, the smaller of the first high-frequency mode in the intra-frame mode frequency table and intra-frame prediction mode A is assigned to the first intra-frame prediction mode, and the larger is assigned to the second intra-frame prediction mode; otherwise, the smaller of the second high-frequency mode in the intra-frame mode frequency table and intra-frame prediction mode A is assigned to the first intra-frame prediction mode, and the larger is assigned to the second intra-frame prediction mode.

[0072] The performance of video coding is improved by adaptively assigning values ​​according to image content and considering block copy intra prediction mode.

[0073] (3) The luma intra prediction mode of the luma prediction block is derived according to the intra luma prediction mode of the luma prediction block and the first intra prediction mode and the second intra prediction mode.

[0074] In one embodiment, if the intra-frame luminance prediction mode value is 0, the first intra-frame prediction mode is assigned to the luminance intra-frame prediction mode of the luminance prediction block; if the normal intra-frame luminance prediction mode is identified as 1, the second intra-frame prediction mode is assigned to the luminance intra-frame prediction mode of the luminance prediction block.

[0075] (II) According to an embodiment of the present invention, if the content of the luma prediction block of the current coding unit is identified as non-natural (screen) content, the luma intra prediction mode of the luma prediction block is obtained as follows:

[0076] (1) Obtain intra-frame prediction mode A and intra-frame prediction mode B according to the information of the adjacent prediction units of the current luminance prediction block.

[0077] In one embodiment, if the left prediction block A "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of A is assigned to intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to 12 (in another embodiment, the value is 24); if the upper prediction block B "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to 12 (in another embodiment, the value is 24).

[0078] It should be noted that for the prediction blocks of natural content and non-natural content, the values ​​assigned are different when the prediction block A on the left or the prediction block B above "exists" and the conditions for the normal intra-frame prediction mode are not met. In this embodiment, the value assigned when the prediction block is natural content is 0, and the value assigned when the prediction block is non-natural content is 12 or 24. Other values ​​can also be assigned respectively, and there is no restriction here.

[0079] In another embodiment, if the left prediction block A "exists" and is in a normal intra-frame prediction mode and the content of the coding unit where A is located is identified as non-natural (screen) content, then the intra-frame prediction mode of A is assigned to intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to 12 (in another embodiment, the value is assigned to 24); if the upper prediction block B "exists" and is in a normal intra-frame prediction mode and the content of the coding unit where B is located is identified as non-natural (screen) content, then the intra-frame prediction mode of B is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to 12 (in another embodiment, the value is assigned to 24).

[0080] In another embodiment, if the left prediction block A "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of A is assigned to intra-frame prediction mode A; if the left prediction block A "exists" and is in block copy intra-frame prediction mode, and the reference block pointed to by A is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by A is assigned to intra-frame prediction mode A; otherwise, the intra-frame prediction mode A is assigned to 12 (in another embodiment, the value is 24). If the upper prediction block B "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to intra-frame prediction mode B; if the upper prediction block B "exists" and is in block copy intra-frame prediction mode, and the reference block pointed to by B is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by B is assigned to intra-frame prediction mode B; otherwise, the intra-frame prediction mode B is assigned to 12 (in another embodiment, the value is 24).

[0081] In another embodiment, if the left prediction block A "exists" and is in a normal intra-frame prediction mode, the intra-frame prediction mode of A is assigned to the intra-frame prediction mode A; if the left prediction block A "exists" and is in a block copy intra-frame prediction mode, and the reference block pointed to by A is in a normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by A is assigned to the intra-frame prediction mode A; if the left prediction block A "exists" and is in a block copy intra-frame prediction mode, and the reference block pointed to by A is not a normal intra-frame prediction mode, but the adjacent block of the reference block pointed to by A is a normal intra-frame prediction mode, then the intra-frame prediction mode of the adjacent block of the reference block pointed to by A is assigned to the intra-frame prediction mode A; otherwise, the intra-frame prediction mode A is assigned to 12 (in another embodiment, it is assigned to 24). If the upper prediction block B "exists" and is in normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to intra-frame prediction mode B; if the upper prediction block B "exists" and is in block copy intra-frame prediction mode, and the reference block pointed to by B is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by B is assigned to intra-frame prediction mode B; if the upper prediction block B "exists" and is in block copy intra-frame prediction mode, and the reference block pointed to by B is not in normal intra-frame prediction mode, but the adjacent block of the reference block pointed to by B is in normal intra-frame prediction mode, the intra-frame prediction mode of the adjacent block of the reference block pointed to by B is assigned to intra-frame prediction mode B; otherwise, the intra-frame prediction mode B is assigned to 12 (in another embodiment, it is assigned to 24).

[0082] The performance of video coding is improved by adaptively assigning values ​​according to image content and considering block copy intra prediction mode.

[0083] (2) The first intra prediction mode and the second intra prediction mode are derived according to the obtained intra prediction mode A and intra prediction mode B.

[0084] In one embodiment, if intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is equal to 12, then intra-frame prediction mode A is assigned a value of 12, and intra-frame prediction mode B is assigned a value of 24. If intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is not equal to 12, then intra-frame prediction mode A is assigned a value of 12. The smaller of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode. The values ​​assigned in this embodiment are 12 and 24, and may also be other values, which are not limited here, but must be different from the values ​​assigned to the natural content prediction unit.

[0085] In another embodiment, if intra-frame prediction mode A is not equal to intra-frame prediction mode B, the smaller of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger is assigned to the second intra-frame prediction mode. If intra-frame prediction mode A is equal to intra-frame prediction mode B and intra-frame prediction mode A is equal to 12, the first high-frequency mode in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the second high-frequency mode in the intra-frame mode frequency table is assigned to the second intra-frame prediction mode. If intra-frame prediction mode A is equal to intra-frame prediction mode B and intra-frame prediction mode A is not equal to 12, if the first high-frequency mode in the intra-frame mode frequency table is not equal to intra-frame prediction mode A, the smaller of the first high-frequency mode in the intra-frame mode frequency table and intra-frame prediction mode A is assigned to the first intra-frame prediction mode, and the larger is assigned to the second intra-frame prediction mode; otherwise, the smaller of the second high-frequency mode in the intra-frame mode frequency table and intra-frame prediction mode A is assigned to the first intra-frame prediction mode, and the larger is assigned to the second intra-frame prediction mode.

[0086] The performance of video coding is improved by adaptively assigning values ​​according to image content and considering block copy intra prediction mode.

[0087] (3) The luma intra prediction mode of the luma prediction block is derived according to the intra luma prediction mode of the luma prediction block and the first intra prediction mode and the second intra prediction mode.

[0088] In one embodiment, if the intra-frame luma prediction mode value is 0, the first intra-frame prediction mode is assigned to the prediction mode of the luma prediction block; if the intra-frame luma prediction mode identifier is 1, the second intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block.

[0089] It should be noted that in this embodiment, the adjacent prediction block A of the current brightness prediction block is the prediction block on the left, and B is the prediction block above. It can also be an adjacent prediction block at other positions, or more than two adjacent prediction blocks. There is no restriction on the position and number of adjacent prediction blocks.

[0090] At step 404a, ordinary intra-frame prediction is performed according to the derived luma intra-frame prediction mode of the luma prediction block to obtain luma samples.

[0091] The luminance intra-frame prediction mode of the luminance prediction block is obtained according to the obtained content identifier of the luminance prediction block of the current coding unit, thereby improving the performance of video coding.

[0092] Figure 4b Another flowchart of the intra-frame prediction method of a video decoder according to an embodiment of the present invention is shown. Figure 4b The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 4bThe embodiments shown are subject to adaptations and modifications.

[0093] refer to Figure 4b , at step 401b, the content identifier of the luma prediction block of the current coding unit is obtained.

[0094] At step 402b, the luma intra prediction mode of the luma prediction block is obtained according to the obtained content identifier.

[0095] Figure 5a is a flowchart illustrating an intra-frame prediction method of a video decoder according to an embodiment of the present invention. Figure 5a The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 5a The embodiments shown are subject to adaptations and modifications.

[0096] refer to Figure 5a , at step 501a, determining that the luma prediction block of the current coding unit is in a normal intra prediction mode, and obtaining the intra luma prediction mode of the current luma prediction block;

[0097] At step 502a, the luma intra prediction mode of the luma prediction block is obtained according to the frequency intra mode coding enable flag.

[0098] According to an embodiment of the present invention, the luma intra prediction mode of the luma prediction block is obtained according to the neighboring prediction units of the current luma prediction block and the information of the intra mode frequency table in the following steps:

[0099] (1) Obtain intra-frame prediction mode A and intra-frame prediction mode B according to the information of the adjacent prediction units of the current luminance prediction block and the intra-frame mode frequency table.

[0100] If the value of the frequency intra-frame mode encoding enable flag is 1, intra-frame prediction mode A and intra-frame prediction mode B are obtained based on the adjacent prediction units of the current luminance prediction block and the information in the intra-frame mode frequency table. If the left prediction block A "exists" and is a normal intra-frame prediction mode, the intra-frame prediction mode of A is assigned to intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to the first high-frequency mode in the intra-frame mode frequency table; if the upper prediction block B "exists" and is a normal intra-frame prediction mode, the intra-frame prediction mode of B is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to one of the first and second high-frequency modes in the intra-frame mode frequency table that is not equal to intra-frame prediction mode A.

[0101] If the value of the frequency intra mode coding enable flag is 0, intra prediction mode A and intra prediction mode B are obtained based on the information of the adjacent prediction units of the current luminance prediction block. If the left prediction block A "exists" and is in normal intra prediction mode, the intra prediction mode of A is assigned to intra prediction mode A, otherwise the intra prediction mode A is assigned to 0; if the upper prediction block B "exists" and is in normal intra prediction mode, the intra prediction mode of B is assigned to intra prediction mode B, otherwise the intra prediction mode B is assigned to 0.

[0102] By adaptively assigning values ​​according to image content, the performance of video encoding is improved.

[0103] (2) The first intra prediction mode and the second intra prediction mode are derived according to the obtained intra prediction mode A and intra prediction mode B.

[0104] In one embodiment, if intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is equal to 0, then intra-frame prediction mode A is assigned a value of 0 and intra-frame prediction mode B is assigned a value of 2. If intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is not equal to 0, then intra-frame prediction mode A is assigned a value of 0. The smaller of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode. The values ​​assigned in this embodiment are 0 and 2, but other values ​​may also be used and are not limited here.

[0105] In another embodiment, if intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is equal to 12, then intra-frame prediction mode A is assigned a value of 12, and intra-frame prediction mode B is assigned a value of 24. If intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is not equal to 12, then intra-frame prediction mode A is assigned a value of 12. The smaller value of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode. The values ​​assigned in this embodiment are 12 and 24, but other values ​​may also be used and are not limited here.

[0106] By adaptively assigning values ​​according to image content, the performance of video encoding is improved.

[0107] (3) The luma intra prediction mode of the luma prediction block is derived according to the intra luma prediction mode of the luma prediction block and the first intra prediction mode and the second intra prediction mode.

[0108] In one embodiment, if the intra-frame luminance prediction mode value is 0, the first intra-frame prediction mode is assigned to the luminance intra-frame prediction mode of the luminance prediction block; if the normal intra-frame luminance prediction mode is identified as 1, the second intra-frame prediction mode is assigned to the luminance intra-frame prediction mode of the luminance prediction block.

[0109] In step 503a, ordinary intra-frame prediction is performed according to the derived luma intra-frame prediction mode of the luma prediction block to obtain luma samples.

[0110] The luminance intra prediction mode of the luminance prediction block is obtained according to the information of the adjacent prediction units and the intra mode frequency table of the current luminance prediction block, and the value is adaptively assigned according to the image content, thereby improving the performance of video coding.

[0111] Figure 5b is another flow chart illustrating an intra-frame prediction method of a video decoder according to an embodiment of the present invention. Figure 5b The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 5b The embodiments shown are subject to adaptations and modifications.

[0112] refer to Figure 5b , at step 501b, obtain information of the intra-frame mode frequency table.

[0113] At step 502b, the luma intra prediction mode of the luma prediction block is obtained according to the information in the intra mode frequency table.

[0114] Figure 6 The flowchart of the method for encoding the content identifier of the image content type at the encoding end is shown. Figure 6 The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 6 The embodiments shown are subject to adaptations and modifications.

[0115] refer to Figure 6 , at step 601, the original image of the current image to be encoded is obtained.

[0116] At step 602, a hash table is constructed. For each hash value, it is calculated whether the value corresponds to two or more blocks. When the probability of the above situation occurring is greater than a certain threshold, the current image to be encoded is a non-natural (screen) content image, and the content identifier is assigned a value of 1; otherwise, the current image to be encoded is a natural content image, and the content identifier is assigned a value of 0.

[0117] At step 603, the content identifier of the current image is written into the code stream.

[0118] Figure 7 A flowchart of a method for decoding image content types at a decoding end is shown. Figure 7 The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 7 The embodiments shown are subject to adaptations and modifications.

[0119] refer to Figure 7 At step 701, the image content identifier of the current image to be decoded is obtained from the code stream.

[0120] At step 702, the content type of the current image to be decoded is obtained according to the image content identifier.

[0121] Figure 8 The flowchart of the content identification encoding method of the content type of the encoding unit at the encoding end is shown. Figure 8 The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 8 The embodiments shown are subject to adaptations and modifications.

[0122] refer to Figure 8 , at step 801, the original image of the current coding unit to be encoded is obtained.

[0123] At step 802, convolution is performed using a Sobel operator. When the calculated Sobel value is greater than a certain threshold, the current coding unit to be encoded is a non-natural (screen) content image, and the content identifier is assigned a value of 1; otherwise, the current coding unit to be encoded is a natural content image, and the content identifier is assigned a value of 0.

[0124] At step 803, the content identifier of the current coding unit is written into the code stream.

[0125] If only the maximum coding unit is identified, then only the content identifier of the current maximum coding unit needs to be written into the bitstream; if the identified coding unit is not only the maximum coding unit, then the size information of the identified coding unit and the content identifier of the coding unit are written into the bitstream together.

[0126] Figure 9 A flowchart of a method for decoding content types of coding units at a decoding end is shown. Figure 9 The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 9 The embodiments shown are subject to adaptations and modifications.

[0127] refer to Figure 9 At step 901, the content identifier of the current coding unit is obtained, or the relevant coding unit size information is obtained at the same time.

[0128] At step 902, the content type of the current coding unit is derived according to the content identifier of the current coding unit, or the content identifier and related coding unit size information.

[0129] Figure 10 A flow chart of a method for deriving a content identifier of a content type of an encoding unit at a decoding end is shown. Figure 10The embodiment of the method shown is for illustration only and other methods may be used without departing from the scope of the present disclosure. Figure 10 The embodiments shown are subject to adaptations and modifications.

[0130] refer to Figure 10 , at step 1001, the adjacent prediction unit information of the current coding unit is obtained.

[0131] At step 1002, the content type of the current coding unit is derived according to the neighboring prediction unit information of the current coding unit.

[0132] In one embodiment, if there is one (or two, not limited here) prediction unit whose prediction mode is a block copy intra prediction mode among the adjacent prediction units of the current coding unit, then the current coding unit is a non-natural (screen) content type; otherwise, it is a natural content type.

[0133] Figure 11 A block diagram of a video decoder performing an intra prediction method is shown. Figure 11 The embodiments shown are for illustration only and other embodiments may be used without departing from the scope of the present disclosure. Figure 11 The embodiments shown are subject to adaptations and modifications.

[0134] refer to Figure 11 According to an embodiment of the present invention, a video decoder 1100 for performing an intra-frame prediction method includes: an intra-frame luminance prediction mode acquisition module 1101, which is configured to determine that the luminance prediction block of the current coding unit is a normal intra-frame prediction mode, and obtain the intra-frame luminance prediction mode of the current luminance prediction block; a content identification acquisition module 1102, which is configured to obtain the content identification of the luminance prediction block of the current coding unit; a prediction mode acquisition module 1103, which is configured to obtain the luminance intra-frame prediction mode of the luminance prediction block according to the obtained content identification; and a luminance sample value acquisition module 1104, which is configured to perform normal intra-frame prediction according to the derived prediction mode of the current luminance prediction block to obtain luminance samples.

[0135] Figure 12 A block diagram of a video decoder performing an intra prediction method is shown. Figure 12 The embodiments shown are for illustration only and other embodiments may be used without departing from the scope of the present disclosure. Figure 12 The embodiments shown are subject to adaptations and modifications.

[0136] refer to Figure 12According to an embodiment of the present invention, a video decoder 1200 for performing an intra-frame prediction method includes: an intra-frame prediction mode acquisition module 1201, which is configured to determine that the luminance prediction block of the current coding unit is a normal intra-frame prediction mode, and obtain the intra-frame luminance prediction mode of the current luminance prediction block; an intra-frame mode frequency table acquisition module 1202, which is configured to obtain information of the intra-frame mode frequency table; a prediction mode acquisition module 1203, which is configured to obtain the luminance intra-frame prediction mode of the luminance prediction block according to the adjacent prediction units of the current luminance prediction block and the information of the intra-frame mode frequency table; a luminance sample value acquisition module 1204, which is configured to perform normal intra-frame prediction according to the derived prediction mode of the current luminance prediction block to obtain luminance samples.

[0137] The present invention also discloses an electronic device, which includes: a memory configured to store a computer program; and a processor configured to read the computer program from the memory, run the computer program, and implement the above method.

[0138] The above-mentioned application combination of step blocks and division of step blocks are only for illustration. Without departing from the scope of the present disclosure, the application combination and division of step blocks may be in different ways.

[0139] Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.

[0140] Nothing in this application should be construed as implying that any particular element, step, or function is essential to be included in the claims scope. The scope of the patented subject matter is limited only by the claims.

Claims

1. A method for obtaining a prediction mode of a video decoder, comprising: Obtaining the content identifier of the luma prediction block of the current coding unit; Obtain the luma intra prediction mode of the luma prediction block according to the obtained content identifier, The luma intra prediction mode of the luma prediction block is obtained according to the obtained content identifier, including: The intra-frame prediction mode A and the intra-frame prediction mode B are obtained according to the obtained content identifier. When the prediction block A and the prediction block B exist and the intra-frame prediction mode of the prediction block A and the prediction block B is not a common intra-frame prediction mode, the values ​​of the intra-frame prediction mode A and the intra-frame prediction mode B are different according to the obtained content identifier. A first intra-frame prediction mode and a second intra-frame prediction mode are derived based on the obtained intra-frame prediction mode A and intra-frame prediction mode B. If the intra-frame prediction mode A is not equal to the intra-frame prediction mode B, the smaller value of the intra-frame prediction mode A and the intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode. The luma intra-frame prediction mode of the luma prediction block is derived based on the intra-frame luma prediction mode value of the luma prediction block and the first intra-frame prediction mode and the second intra-frame prediction mode. When the intra-frame luma prediction mode value is 0, the first intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block, and when the intra-frame luma prediction mode value is 1, the second intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block.

2. The method according to claim 1, wherein Obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier further includes: When the obtained content identifier is the first content identifier, if prediction block A exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of prediction block A to intra-frame prediction mode A, otherwise assigning the intra-frame prediction mode A to a first predetermined value; if prediction block B exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of prediction block B to intra-frame prediction mode B, otherwise assigning the intra-frame prediction mode B to the first predetermined value; When the obtained content identifier is the second content identifier, if prediction block A exists and is in normal intra-frame prediction mode, the intra-frame prediction mode of prediction block A is assigned to intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to the second predetermined value; if prediction block B exists and is in normal intra-frame prediction mode, the intra-frame prediction mode of prediction block B is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to the second predetermined value.

3. The method according to claim 1, wherein Obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier further includes: In a case where the obtained content identifier is the first content identifier, if prediction block A exists and is in a normal intra-frame prediction mode and the content identifier of the coding unit where prediction block A is located is the first content identifier, assigning the intra-frame prediction mode of prediction block A to intra-frame prediction mode A; otherwise, assigning the intra-frame prediction mode A to a first predetermined value; if prediction block B exists and is in a normal intra-frame prediction mode and the coding unit where prediction block B is located is the first content identifier, assigning the intra-frame prediction mode of prediction block B to intra-frame prediction mode B; otherwise, assigning the intra-frame prediction mode B to the first predetermined value; When the obtained content identifier is the second content identifier, if prediction block A exists and is in a normal intra-frame prediction mode and the content identifier of the coding unit where prediction block A is located is the second content identifier, the intra-frame prediction mode of prediction block A is assigned to intra-frame prediction mode A, otherwise the intra-frame prediction mode A is assigned to the second predetermined value; if prediction block B exists and is in a normal intra-frame prediction mode and the coding unit where prediction block B is located is the second content identifier, the intra-frame prediction mode of prediction block B is assigned to intra-frame prediction mode B, otherwise the intra-frame prediction mode B is assigned to the second predetermined value.

4. The method according to claim 1, wherein Obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier further includes: In a case where the obtained content identifier is the first content identifier, if prediction block A exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of prediction block A to intra-frame prediction mode A; otherwise, assigning the intra-frame prediction mode A to a first predetermined value; if prediction block B exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of prediction block B to intra-frame prediction mode B; otherwise, assigning the intra-frame prediction mode B to the first predetermined value; When the obtained content identifier is the second content identifier, if prediction block A exists and is in normal intra-frame prediction mode, the intra-frame prediction mode of prediction block A is assigned to intra-frame prediction mode A; if prediction block A exists and is in block copy intra-frame prediction mode, and the reference block pointed to by prediction block A is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by prediction block A is assigned to intra-frame prediction mode A; otherwise, intra-frame prediction mode A is assigned to a second predetermined value; if prediction block B exists and is in normal intra-frame prediction mode, the intra-frame prediction mode of prediction block B is assigned to intra-frame prediction mode B; if prediction block B exists and is in block copy intra-frame prediction mode, and the reference block pointed to by prediction block B is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by prediction block B is assigned to intra-frame prediction mode B; otherwise, intra-frame prediction mode B is assigned to the second predetermined value.

5. The method according to claim 1, wherein Obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the obtained content identifier further includes: In a case where the obtained content identifier is the first content identifier, if prediction block A exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of prediction block A to intra-frame prediction mode A; otherwise, assigning the intra-frame prediction mode A to a first predetermined value; if prediction block B exists and is in a normal intra-frame prediction mode, assigning the intra-frame prediction mode of prediction block B to intra-frame prediction mode B; otherwise, assigning the intra-frame prediction mode B to the first predetermined value; In the case where the obtained content identifier is the second content identifier, if the prediction block A exists and is in the normal intra-frame prediction mode, the intra-frame prediction mode of the prediction block A is assigned to the intra-frame prediction mode A; if the prediction block A exists and is in the block copy intra-frame prediction mode, and the reference block pointed to by the prediction block A is in the normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by the prediction block A is assigned to the intra-frame prediction mode A; if the prediction block A exists and is in the block copy intra-frame prediction mode, and the reference block pointed to by the prediction block A is not the normal intra-frame prediction mode, but the adjacent block of the reference block pointed to by the prediction block A is the normal intra-frame prediction mode, the intra-frame prediction mode of the adjacent block of the reference block pointed to by the prediction block A is assigned to the intra-frame prediction mode A; otherwise, the intra-frame prediction mode A is assigned a second predetermined value; if prediction block B exists and is in normal intra-frame prediction mode, the intra-frame prediction mode of prediction block B is assigned to intra-frame prediction mode B; if prediction block B exists and is in block copy intra-frame prediction mode, and the reference block pointed to by prediction block B is in normal intra-frame prediction mode, the intra-frame prediction mode of the reference block pointed to by prediction block B is assigned to intra-frame prediction mode B; if prediction block B exists and is in block copy intra-frame prediction mode, and the reference block pointed to by prediction block B is not in normal intra-frame prediction mode, but the adjacent block of the reference block pointed to by prediction block B is in normal intra-frame prediction mode, the intra-frame prediction mode of the adjacent block of the reference block pointed to by prediction block B is assigned to intra-frame prediction mode B; otherwise, intra-frame prediction mode B is assigned to the second predetermined value.

6. The method according to claim 1, wherein Deriving the first intra prediction mode and the second intra prediction mode based on the obtained intra prediction mode A and the intra prediction mode B further includes: In a case where the obtained content identifier is a first content identifier, if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the first predetermined value, then the intra-frame prediction mode B is assigned to the second predetermined value; if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is not equal to the first predetermined value, then the intra-frame prediction mode A is assigned to the first predetermined value; the smaller of the intra-frame prediction mode A and the intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode, When the obtained content identifier is the second content identifier, if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the third predetermined value, then the intra-frame prediction mode B is assigned to the fourth predetermined value; if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is not equal to the third predetermined value, then the intra-frame prediction mode A is assigned to the third predetermined value; the smaller of the intra-frame prediction mode A and the intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode.

7. The method according to claim 1, wherein Deriving the first intra prediction mode and the second intra prediction mode based on the obtained intra prediction mode A and the intra prediction mode B further includes: In the case where the obtained content identifier is the first content identifier, if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the first predetermined value, then the first high-frequency mode in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the second high-frequency mode in the intra-frame mode frequency table is assigned to the second intra-frame prediction mode; if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is not equal to the first predetermined value, if the first high-frequency mode in the intra-frame mode frequency table is not equal to the intra-frame prediction mode A, then the smaller value of the first high-frequency mode and the intra-frame prediction mode A in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode; otherwise, the smaller value of the second high-frequency mode and the intra-frame prediction mode A in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode. When the obtained content identifier is the second content identifier, if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the second predetermined value, the first high-frequency mode in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the second high-frequency mode in the intra-frame mode frequency table is assigned to the second intra-frame prediction mode; if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is not equal to the second predetermined value, if the first high-frequency mode in the intra-frame mode frequency table is not equal to the intra-frame prediction mode A, the smaller value of the first high-frequency mode and the intra-frame prediction mode A in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode; otherwise, the smaller value of the second high-frequency mode and the intra-frame prediction mode A in the intra-frame mode frequency table is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode.

8. The method according to claim 1, wherein The content identification includes a frame-level identification and / or a coding unit-level identification.

9. The method according to claim 1, wherein The content identifier is obtained by parsing the bitstream or is derived at the video decoder.

10. The method according to claim 9, wherein: The content identifier is derived at the video decoder, including: obtaining neighboring prediction unit information of the current coding unit, and deriving the content identifier of the current coding unit according to the neighboring prediction unit information of the current coding unit.

11. The method according to claim 1 , further comprising: The content type of the current coding unit is derived based on the content identifier and the related coding unit size information.

12. A video decoder according to a prediction mode acquisition method, comprising: A content identification acquisition module configured to obtain a content identification of a luminance prediction block of a current coding unit; A prediction mode acquisition module is configured to obtain a luma intra-frame prediction mode of a luma prediction block according to the obtained content identifier, The luma intra prediction mode of the luma prediction block is obtained according to the obtained content identifier, including: The intra-frame prediction mode A and the intra-frame prediction mode B are obtained according to the obtained content identifier. When the prediction block A and the prediction block B exist and the intra-frame prediction mode of the prediction block A and the prediction block B is not a common intra-frame prediction mode, the values ​​of the intra-frame prediction mode A and the intra-frame prediction mode B are different according to the obtained content identifier. A first intra-frame prediction mode and a second intra-frame prediction mode are derived based on the obtained intra-frame prediction mode A and intra-frame prediction mode B. If the intra-frame prediction mode A is not equal to the intra-frame prediction mode B, the smaller value of the intra-frame prediction mode A and the intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode. The luma intra-frame prediction mode of the luma prediction block is derived based on the intra-frame luma prediction mode value of the luma prediction block and the first intra-frame prediction mode and the second intra-frame prediction mode. When the intra-frame luma prediction mode value is 0, the first intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block, and when the intra-frame luma prediction mode value is 1, the second intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block.

13. A method for obtaining a prediction mode of a video decoder, comprising: Obtain information of the intra-frame mode frequency table; Obtain the luma intra prediction mode of the luma prediction block according to the information in the intra mode frequency table. The luma intra prediction mode of the luma prediction block is obtained according to the information of the intra mode frequency table, including: Obtaining intra-frame prediction mode A and intra-frame prediction mode B according to information in the intra-frame mode frequency table; if the value of the frequency intra-frame mode encoding enable flag is 1, obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the neighboring prediction units of the current luma prediction block and information in the intra-frame mode frequency table; deriving a first intra-frame prediction mode and a second intra-frame prediction mode according to the obtained intra-frame prediction mode A and intra-frame prediction mode B, and if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the first predetermined value, assigning the intra-frame prediction mode A to the first predetermined value and assigning the intra-frame prediction mode B to the second predetermined value; and The luma intra-frame prediction mode of the luma prediction block is derived based on the intra-frame luma prediction mode value of the luma prediction block and the first intra-frame prediction mode and the second intra-frame prediction mode. When the intra-frame luma prediction mode value is 0, the first intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block, and when the intra-frame luma prediction mode value is 1, the second intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block.

14. The method according to claim 13, wherein Obtaining intra prediction mode A and intra prediction mode B according to the information in the intra mode frequency table further includes: If the value of the frequency intra mode coding enable flag is 0, intra prediction mode A and intra prediction mode B are obtained according to information of neighboring prediction units of the current luma prediction block.

15. The method according to claim 14, wherein Obtaining intra prediction mode A and intra prediction mode B according to the information of the intra mode frequency table includes: If prediction block A exists and is in normal intra-frame prediction mode, the intra-frame prediction mode of prediction block A is assigned to intra-frame prediction mode A, otherwise intra-frame prediction mode A is assigned to the first high-frequency mode in the intra-frame mode frequency table; if prediction block B exists and is in normal intra-frame prediction mode, the intra-frame prediction mode of prediction block B is assigned to intra-frame prediction mode B, otherwise intra-frame prediction mode B is assigned to one of the first high-frequency mode and the second high-frequency mode in the intra-frame mode frequency table that is not equal to intra-frame prediction mode A.

16. The method according to claim 13, wherein: Deriving the first intra prediction mode and the second intra prediction mode according to the obtained intra prediction mode A and the intra prediction mode B further includes: If intra-frame prediction mode A is equal to intra-frame prediction mode B, and intra-frame prediction mode A is not equal to the first predetermined value, then the intra-frame prediction mode A is assigned to the predetermined value; the smaller value of intra-frame prediction mode A and intra-frame prediction mode B is assigned to the first intra-frame prediction mode, and the larger value is assigned to the second intra-frame prediction mode.

17. A video decoder for performing a prediction mode acquisition method, comprising: an intra-frame mode frequency table acquisition module, configured to obtain information of the intra-frame mode frequency table; as well as A prediction mode acquisition module is configured to obtain the luma intra prediction mode of the luma prediction block according to the information of the intra mode frequency table, The luma intra prediction mode of the luma prediction block is obtained according to the information of the intra mode frequency table, including: Obtaining intra-frame prediction mode A and intra-frame prediction mode B according to information in the intra-frame mode frequency table; if the value of the frequency intra-frame mode encoding enable flag is 1, obtaining intra-frame prediction mode A and intra-frame prediction mode B according to the neighboring prediction units of the current luma prediction block and information in the intra-frame mode frequency table; deriving a first intra-frame prediction mode and a second intra-frame prediction mode according to the obtained intra-frame prediction mode A and intra-frame prediction mode B, and if the intra-frame prediction mode A is equal to the intra-frame prediction mode B, and the intra-frame prediction mode A is equal to the first predetermined value, assigning the intra-frame prediction mode A to the first predetermined value and assigning the intra-frame prediction mode B to the second predetermined value; and The luma intra-frame prediction mode of the luma prediction block is derived based on the intra-frame luma prediction mode value of the luma prediction block and the first intra-frame prediction mode and the second intra-frame prediction mode. When the intra-frame luma prediction mode value is 0, the first intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block, and when the intra-frame luma prediction mode value is 1, the second intra-frame prediction mode is assigned to the luma intra-frame prediction mode of the luma prediction block.

18. An electronic device comprising: a memory configured to store a computer program; as well as A processor configured to execute the computer program to implement the method according to any one of claims 1-11 and 13-16.

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