LCEVC-based enhancement layer encoding method, apparatus, device, and medium

Abstract

The present disclosure relates to an LCEVC-based enhancement layer coding method, device, equipment and medium, applied to the technical field of video coding, which can improve the coding quality of video coding. The method comprises: in the case of using temporal prediction for a to-be-coded enhancement layer sequence, obtaining the code rate of the current frame base layer corresponding to the current frame enhancement layer and the average code rate of the C frame base layer before the current frame base layer, the to-be-coded enhancement layer sequence comprising a plurality of enhancement layers, and the current frame enhancement layer being any frame in the plurality of enhancement layers; in the case that the code rate of the current frame base layer is less than or equal to the average code rate, coding the current frame enhancement layer based on a first quantization parameter; in the case that the code rate of the current frame base layer is greater than the average code rate, updating the quantization parameter of the current frame enhancement layer from the first quantization parameter to a second quantization parameter, and coding the current frame enhancement layer based on the second quantization parameter, the second quantization parameter being less than the first quantization parameter.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of video coding. More particularly, it relates to an enhancement layer coding method and device based on LCEVC, a terminal device and a storage medium. BACKGROUND

[0002] In the low complexity enhancement video coding (LCEVC) standard, there are a base layer and an enhancement layer. The base layer is generally encoded using an existing video coding standard such as H.264 / H.265, and H.264 / H.265 and the like have relatively mature research on the frame-level code rate allocation method. The enhancement layer is encoded using the tools described in the LCEVC standard, and in the LCEVC standard, there is currently only a fixed quantization parameter coding method, that is, the quantization parameter of each frame of a video sequence is the same. The fixed quantization parameter coding method ignores the differences between video frames.

[0003] Because the content of a video picture is constantly changing, there are differences between frames, and there is a certain arithmetic relationship between the quantization parameter and the coding quality. Therefore, the fixed quantization parameter coding method may affect the coding quality of video coding. SUMMARY

[0004] To solve the above technical problems or at least partially solve the above technical problems, the embodiment of the present application provides an enhancement layer coding method and device based on LCEVC, which can improve the coding quality of video coding.

[0005] In a first aspect, the embodiment of the present application provides an enhancement layer coding method based on LCEVC, comprising:

[0006] In the case of using temporal prediction for the to-be-encoded enhancement layer sequence, the code rate of the current frame base layer corresponding to the current frame enhancement layer is obtained, and the average code rate of the C frame base layer before the current frame base layer is obtained, the to-be-encoded enhancement layer sequence includes multiple enhancement layers, the current frame enhancement layer is any frame in the multiple enhancement layers, the average code rate is the average of the code rate of each frame base layer in the C frame base layer, and C is an integer greater than 1;

[0007] In the case where the code rate of the current frame base layer is less than or equal to the average code rate, the current frame enhancement layer is encoded based on a first quantization parameter;

[0008] In a case where the code rate of the current frame base layer is greater than the average code rate, a quantization parameter of the current frame enhancement layer is updated from a first quantization parameter to a second quantization parameter, the current frame enhancement layer is encoded based on the second quantization parameter, and the second quantization parameter is less than the first quantization parameter.

[0009] In a second aspect, the embodiments of the present application provide an LCEVC-based enhancement layer encoding apparatus, comprising:

[0010] a memory configured to store a computer program;

[0011] a processor configured to, when the computer program is invoked, cause the LCEVC-based enhancement layer encoding apparatus to implement the LCEVC-based enhancement layer encoding method of the first aspect.

[0012] In a third aspect, the embodiments of the present application provide a terminal device, comprising the LCEVC-based enhancement layer encoding apparatus of the second aspect.

[0013] In a fourth aspect, the embodiments of the present application provide a computer-readable storage medium, comprising: a computer program stored on the computer-readable storage medium, the computer program being executed by a processor to implement the LCEVC-based enhancement layer encoding method of the second aspect.

[0014] In a fifth aspect, the embodiments of the present application provide a computer program product, comprising: when the computer program product is run on a computer, causing the computer to implement the LCEVC-based enhancement layer encoding method of the second aspect.

[0015] Compared with the related art, the technical scheme provided by the embodiments of the present application has the following effects: in some embodiments of the present application, in the case that the to-be-encoded enhancement layer sequence uses temporal prediction, the code rate of the current frame base layer corresponding to the current frame enhancement layer of the to-be-encoded enhancement layer sequence and the average code rate of the C frame base layer before the current frame base layer are obtained, in the case that the code rate of the current frame base layer is less than or equal to the average code rate, the current frame enhancement layer is encoded based on a first quantization parameter (original quantization parameter); in the case that the code rate of the current frame base layer is greater than the average code rate, the quantization parameter of the current frame enhancement layer is updated from the first quantization parameter to a second quantization parameter (the second quantization parameter is less than the first quantization parameter, that is, the original quantization parameter is reduced, and the quantization parameter is reduced from the first quantization parameter to the second quantization parameter), and the current frame enhancement layer is encoded based on the second quantization parameter. In this way, in the case that the current frame enhancement layer of the to-be-encoded enhancement layer sequence uses temporal prediction, the coding quality of the current frame is improved by reducing the quantization parameter of the current frame enhancement layer (reducing the quantization parameter can improve the code rate), and since the current frame enhancement layer uses temporal prediction (utilizing the correlation between frames), in the case that the coding quality of the current frame enhancement layer is improved, the coding quality of the subsequent multiple frames of enhancement layers (using inter-frame coding) of the current frame enhancement layer is also relatively improved, thereby improving the average coding quality of video coding. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the implementation manners in the related art, the drawings needed to be used in the embodiments or related art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0017] Figure 1 The structural schematic diagram of the LCEVC encoder in some embodiments of the present application is shown;

[0018] Figure 2 The structural schematic diagram of the temporal prediction process of the LCEVC encoder in some embodiments of the present application is shown;

[0019] Figure 3 The schematic diagram of the motion vector being 0 between the current frame to-be-encoded block and the previous frame to-be-encoded block in some embodiments of the present application is shown;

[0020] Figure 4 One of the flow schematic diagrams of the LCEVC-based enhancement layer encoding method in some embodiments of the present application is shown;

[0021] Figure 5 The other of the flow schematic diagrams of the LCEVC-based enhancement layer encoding method in some embodiments of the present application is shown;

[0022] Figure 6 Fig. 3 shows a flowchart of a method for LCEVC-based enhancement layer encoding according to some embodiments of the present application;

[0023] Figure 7 Fig. 4 shows a flowchart of a method for LCEVC-based enhancement layer encoding according to some embodiments of the present application;

[0024] Figure 8 Fig. 5 shows a flowchart of a method for LCEVC-based enhancement layer encoding according to some embodiments of the present application;

[0025] Figure 9 Fig. 6 shows a flowchart of a method for LCEVC-based enhancement layer encoding according to some embodiments of the present application;

[0026] Figure 10 Fig. 7 shows a schematic diagram of an apparatus for LCEVC-based enhancement layer encoding according to some embodiments of the present application. DETAILED DESCRIPTION

[0027] For the purpose of clarity, the present application will be described with reference to exemplary embodiments described in the following description and attached drawings. It should be appreciated that the exemplary embodiments can be implemented in any number of ways, by any number of configurations. It also should be understood that any number of the features described herein can be combined in any combination. It should be understood that various modifications can be made to the embodiments and implementations described herein, and that such modifications, if within the spirit and scope of the application as defined by the appended claims, are to be considered equivalents. Therefore, specific embodiments discussed and illustrated are meant to be only examples of implementations as presently contemplated by the inventors.

[0028] It should be noted that the brief description of terms in the present application is only for the convenience of understanding the following described embodiments, and is not intended to limit the embodiments of the present application. Unless otherwise specified, these terms should be understood according to their ordinary and general meanings.

[0029] The terms "first", "second", "third", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar or like objects or entities, and do not necessarily mean a specific order or sequence, unless otherwise noted. It should be understood that the terms used in this way can be interchanged under appropriate circumstances.

[0030] The terms "include" and "have" and any variations thereof are intended to cover but not exclusively include, for example, a product or device that includes a list of components without being limited to all the components clearly listed, but can include other components that are not clearly listed or inherent to such products or devices.

[0031] The LCEVC-based enhancement layer coding method provided in some embodiments of the present application is used to optimize the coding process of the first enhancement layer and the second enhancement layer of the LCEVC encoder, so as to improve the coding quality of the enhancement layer of some frames, and further improve the average coding quality of video coding. Therefore, first, the structure of the LCEVC encoder is described below.

[0032] Referring to Figure 1 As shown in the figure, the LCEVC encoder includes a first down-sampling layer 11, a second down-sampling layer 12, a base layer 13, a first up-sampling layer 14, a first enhancement layer 15, an L1 residual reconstruction layer 16, a fusion layer 17, a second up-sampling layer 18, and a second enhancement layer 19.

[0033] The first down-sampling layer 11 is used to down-sample the video to be coded, so as to reduce the resolution of the video to be coded.

[0034] The second down-sampling layer 12 is used to further down-sample the output of the first down-sampling layer 11, so as to further reduce the resolution of the video frames of the video to be coded. It should be noted that in the LCEVC standard, there are two processes of down-sampling, and the down-sampling method of each layer or whether to perform down-sampling can be selected according to actual needs, which is not limited here.

[0035] The base layer 13 is used to code the output of the second down-sampling layer 12 by a base layer encoder, so as to generate a base layer bitstream. It should be noted that the base layer encoder can be any encoder, such as x264, x265, a High Efficiency Video Coding (HEVC) encoder, a Versatile Video Coding (VVC) encoder, etc. The base layer is also called a basic layer or a bottom layer.

[0036] The first up-sampling layer 14 is used to up-sample the coding reconstruction image of the base layer 13, so as to improve the resolution of the coding reconstruction image of the base layer 13.

[0037] The first enhancement layer 15 is used to calculate the residual (L1 residual) of the output of the first down-sampling layer 11 and the output of the first up-sampling layer 14, and sequentially perform transform, quantization and entropy coding on the L1 residual, so as to obtain L1 enhancement coefficients.

[0038] The L1 residual reconstruction layer 16 is used to sequentially perform dequantization, inverse transform and filtering on the data obtained by the quantization of the first enhancement layer 15, so as to obtain the output of the L1 residual reconstruction layer 16, i.e., the reconstructed L1 residual.

[0039] The fusion layer 17 is used to add and fuse the output of the L1 residual reconstruction layer 16 and the output of the first up-sampling layer 14, so as to obtain the output of the fusion layer 17.

[0040] The second upsampling layer 18 is used to upsample the output of the fusion layer 17 to improve the resolution of the image output by the fusion layer 17. The resolution of the output of the second upsampling layer 18 is consistent with the resolution of the original video to be encoded.

[0041] The second enhancement layer 19 is used to calculate the difference image between the output of the second upsampling layer 18 and the original video to be encoded, i.e., the L2 residual. Temporal prediction can be performed on the L2 residual as needed. The generated prediction coefficients can be compressed and transmitted to the terminal device. The L2 residual is also transformed, quantized and entropy encoded in sequence to obtain the L2 enhancement coefficients.

[0042] Temporal prediction in the LCEVC encoder is used to determine whether to encode the L2 residual in intra-frame mode or inter-frame mode. For example... Figure 2 The diagram shown illustrates the specific process of time-domain prediction, mainly comprising sections 21 to 26. The following sections will discuss... Figure 2 The various processes in the process are explained in detail, including:

[0043] Specifically, 21 involves subtracting the L2 residual of the previous frame from the L2 residual of the current frame to reconstruct the inter-frame prediction residual (inter_resi);

[0044] Specifically, 22 involves transforming and quantizing inter_resi to obtain inter_symbols; and then performing inverse quantization and inverse transform on inter_symbols to obtain inter_resi_recon.

[0045] Specifically, inter_resi_recon is added to the L2 residual reconstruction of the previous frame and the upsampled image of the current frame to obtain the inter-frame reconstructed image (inter_recon); based on inter_recon and inter_symbols, the inter-frame rate distortion cost (inter_cost) is calculated.

[0046] 24 Specifically, the L2 residual of the current frame is directly transformed and quantized to obtain intra-symbols; intra-symbols are then dequantized and de-transformed to obtain intra-residual reconstruction.

[0047] 25 Specifically, intra_resi_recon is added to the upsampled image of the current frame to obtain the intra-reconstructed image (intra_recon); based on intra_recon and intra_symbols, the intra-rate distortion cost (intra_cost) is calculated.

[0048] 26Specifically, it is determined whether the inter-frame rate-distortion cost is greater than the intra-frame rate-distortion cost; in the case where the inter-frame rate-distortion cost is greater than the intra-frame rate-distortion cost, it is determined that the intra-frame mode is selected, and then the L2 residual coding of the current frame is performed based on the intra-frame mode; in the case where the inter-frame rate-distortion cost is less than or equal to the intra-frame rate-distortion cost, it is determined that the inter-frame mode is selected, and then the L2 residual coding of the current frame is performed based on the inter-frame mode.

[0049] In the case of using temporal prediction, the motion vector of the current frame and the previous frame is always 0. Exemplarily, as shown in (B) of FIG. 1, a current to-be-encoded block of a current to-be-encoded image is (a, b), as shown in (A) of FIG. 1, a reference block of the previous to-be-encoded image corresponding to the current to-be-encoded block is also (a, b), so the current to-be-encoded block and the reference block are two same blocks in the current to-be-encoded image and the previous to-be-encoded image, and in this case, the motion vector of the current to-be-encoded block and the reference block is 0. In the LCEVC encoder, in the case of using temporal prediction for L2 residual, the motion vector of each to-be-encoded block of the current to-be-encoded image and the reference block in the corresponding previous to-be-encoded block is 0. Figure 3 Figure 3 In the case of using temporal prediction, the motion vector of the current frame and the previous frame is always 0. Exemplarily, as shown in (B) of FIG. 1, a current to-be-encoded block of a current to-be-encoded image is (a, b), as shown in (A) of FIG. 1, a reference block of the previous to-be-encoded image corresponding to the current to-be-encoded block is also (a, b), so the current to-be-encoded block and the reference block are two same blocks in the current to-be-encoded image and the previous to-be-encoded image, and in this case, the motion vector of the current to-be-encoded block and the reference block is 0. In the LCEVC encoder, in the case of using temporal prediction for L2 residual, the motion vector of each to-be-encoded block of the current to-be-encoded image and the reference block in the corresponding previous to-be-encoded block is 0.

[0050] The relationship between the quantization parameter, the code rate and the coding quality of the video is introduced below.

[0051] According to the existing research on the code rate control algorithm and the experimental research on the LCEVC standard, it is found that the logarithmic model can be used to describe the relationship between the quantization parameter and the code rate, as shown in formula (1).

[0052] Q = λ · lnR + γ (1)

[0053] Wherein, Q is the quantization parameter, R is the code rate, λ and γ are the coefficients of the relationship model between the quantization parameter and the code rate. From formula (1), it can be obtained that there is a linear relationship between the quantization parameter and the logarithm of the code rate, and in the actual situation, λ is a value less than 0, so the quantization parameter decreases with the increase of the code rate; the quantization parameter increases with the decrease of the code rate. That is, the quantization parameter increases, and the code rate decreases; the quantization parameter decreases, and the code rate increases.

[0054] In addition, it is found through experimental research that there is also a similar relationship between the code rate and the coding quality of the video (here, the objective index vmaf close to the subjective is used to measure), that is, the logarithmic relationship can also be used to describe, as shown in formula (2).

[0055] vmaf = α · lnR + β (2)

[0056] ​Wherein, vmaf is the encoding quality, R is the code rate, and a, b are the coefficients of the relationship model between the encoding quality and the code rate. It can be obtained from formula (2) that the encoding quality and the logarithm of the code rate are also in a linear relationship, and in actual situations, a is a value greater than 0, so the encoding quality increases with the increase of the code rate; the encoding quality decreases with the decrease of the code rate.

[0057] Further, we can deduce that the quality of the video frame and the quantization parameter are approximately in a linear relationship, that is, can be described by formula (3).

[0058] vmaf = a Q + b (3)

[0059] Wherein, vmaf is the encoding quality, Q is the quantization parameter, and a, b are the coefficients of the relationship model between the encoding quality and the quantization parameter.

[0060] It can be obtained from formula (3) that the encoding quality and the quantization parameter are also in a linear relationship, and in actual situations, a is a value less than 0, so the encoding quality decreases with the increase of the quantization parameter; the encoding quality increases with the decrease of the quantization parameter.

[0061] The LCEVC-based enhancement layer encoding method provided by some embodiments of the present application can be applicable to the LCEVC encoding scheme with fixed quantization parameters, can be applicable to the LCEVC encoding scheme with code rate control such as average code rate, and can be applicable to other LCEVC encoding schemes, which are not limited here.

[0062] The standard of LCEVC uses fixed quantization parameter encoding, that is, the quantization parameter of each frame of a video sequence is the same. At present, there is no mature scheme for the code rate allocation of the enhancement layer of LCEVC, but reference can be made to other video encoding standards such as H.264 / AVC and H.265 / HEVC, and an average code rate allocation scheme can be analogously adopted. However, neither the existing fixed quantization parameter encoding nor the average code rate allocation encoding takes into account the differences between frames.

[0063] To solve the above technical problems, in some embodiments of the present application, in the case that the to-be-encoded enhancement layer sequence uses temporal prediction, the code rate of the current frame base layer corresponding to the current frame enhancement layer of the to-be-encoded enhancement layer sequence is obtained, and the average code rate of the C frame base layer before the current frame base layer. In the case that the code rate of the current frame base layer is less than or equal to the average code rate, the current frame enhancement layer is encoded based on the first quantization parameter (original quantization parameter). In the case that the code rate of the current frame base layer is greater than the average code rate, the quantization parameter of the current frame enhancement layer is updated from the first quantization parameter to the second quantization parameter (the second quantization parameter is less than the first quantization parameter, that is, the original quantization parameter is reduced, and the quantization parameter is reduced from the first quantization parameter to the second quantization parameter). The current frame enhancement layer is encoded based on the second quantization parameter. In this way, in the case that the current frame enhancement layer of the to-be-encoded enhancement layer sequence uses temporal prediction, the coding quality of the current frame is improved by reducing the quantization parameter of the current frame enhancement layer (reducing the quantization parameter can improve the code rate). Since the current frame enhancement layer uses temporal prediction (the current frame enhancement layer is usually encoded in inter mode, and the correlation between frames is used), the coding quality of the subsequent multiple frames of the current frame enhancement layer (encoded in inter mode) is also relatively improved, thereby improving the average coding quality of video encoding.

[0064] In some embodiments of the present application, the execution subject of the LCEVC-based enhancement layer encoding method can be a server or a terminal device, or a functional module or functional entity capable of implementing the LCEVC-based enhancement layer encoding method in the server or terminal device. The specific determination can be made according to the actual situation.

[0065] The server can be a server cluster or multiple server clusters, and can include one or more types of servers. The terminal device can be a television, a smart television, a laser projection device, a monitor, an electronic bulletin board, an electronic table, a mobile phone, a tablet computer, a notebook computer, a palm computer, a vehicle-mounted terminal device, etc., which are not limited here.

[0066] Figure 4 To implement the steps of the LCEVC-based enhancement layer encoding method according to one or more embodiments of the present application, the LCEVC-based enhancement layer encoding method can include S401 to S405 as follows.

[0067] S401, in the case that the to-be-encoded enhancement layer sequence uses temporal prediction, the code rate of the current frame base layer corresponding to the current frame enhancement layer of the to-be-encoded enhancement layer sequence is obtained, and the average code rate of the C frame base layer before the current frame base layer.

[0068] The enhancement layer sequence to be encoded includes multiple enhancement layers, the current frame enhancement layer is any frame in the multiple enhancement layers, and the average bitrate is the average bitrate of each frame base layer in the C-frame base layer, where C is an integer greater than 1.

[0069] Where the enhancement layer sequence to be encoded uses temporal prediction, then the enhancement layer sequence to be encoded belongs to Figure 1 L2 residuals in.

[0070] Combination Figure 1 It can be seen that if the enhancement layer sequence to be encoded uses temporal prediction, the enhancement layer sequence to be encoded will be an L2 residual; if the enhancement layer sequence to be encoded uses temporal prediction, the enhancement layer sequence to be encoded may be an L2 residual or an L1 residual.

[0071] S402. Determine whether the bit rate of the current frame's base layer is greater than the average bit rate.

[0072] If the bit rate of the current frame base layer is less than or equal to the average bit rate, perform step S403; if the bit rate of the current frame base layer is greater than the average bit rate, perform steps S404 and S405.

[0073] S403. If the bit rate of the base layer of the current frame is less than or equal to the average bit rate, the enhancement layer of the current frame is encoded based on the first quantization parameter.

[0074] S404. If the bit rate of the base layer of the current frame is greater than the average bit rate, update the quantization parameter of the enhancement layer of the current frame from the first quantization parameter to the second quantization parameter.

[0075] S405. Encode the current frame enhancement layer based on the second quantization parameter, where the second quantization parameter is less than the first quantization parameter.

[0076] In some embodiments of this application, encoding the current frame enhancement layer based on quantization parameters (first quantization parameter or second quantization parameter) includes: transforming the current frame enhancement layer, quantizing the transformed output based on the quantization parameters, and entropy encoding the quantized output to obtain the enhancement coefficients of the current frame enhancement layer after encoding.

[0077] It can be understood that the first quantization parameter is the original quantization parameter of the current frame enhancement layer, and the second quantization parameter is less than the first quantization parameter. That is, when the bit rate of the current frame base layer is less than or equal to the average bit rate, the original quantization parameter is used to encode the current frame enhancement layer. When the bit rate of the current frame base layer is greater than the average bit rate, the original quantization parameter is reduced (the first quantization parameter is reduced to the second quantization parameter), and then the reduced quantization parameter is used to encode the current frame enhancement layer.

[0078] Correspondingly, according to the time domain prediction result, it is determined whether to use the inter-frame mode or the intra-frame mode to encode the current frame of the enhancement layer.

[0079] In the encoding of the LCEVC enhancement layer, the time domain prediction mainly utilizes the correlation between adjacent frames (the current frame and the previous frame) to further improve the performance of compression. Different from the complex video encoding standards such as H.264 / H.265, the time domain prediction in LCEVC mainly reflects that the motion vector is always 0, so the time domain prediction has good compression effect in scenes with little motion. Once there is a large change in the picture content, the performance of the algorithm will decrease. In the encoding process of the base layer, the code rate of the relevant frames is relatively stable in the case of little scene motion. When there is a scene change (the scene has a large change), the code rate of the relevant frames is usually increased. Therefore, the change in the code rate of the base layer can be used to adjust the quantization parameter of some frames of the enhancement layer. That is, in the encoding process of the enhancement layer, the size relationship between the code rate of the current frame of the base layer and the average code rate of the C frames of the base layer before the current frame of the base layer can be used to determine whether there is a large scene change in the current frame of the base layer relative to the previous frame of the base layer, so as to determine whether to adjust the quantization parameter of the current frame of the enhancement layer. Specifically, in the case where the code rate of the current frame of the base layer is less than or equal to the average code rate of the C frames of the base layer before the current frame of the base layer, it is determined that the scene change of the current frame of the base layer relative to the previous frame of the base layer is not large, the motion is not intense, and it is not a scene change frame, so it is not necessary to adjust the quantization parameter of the current frame of the enhancement layer. In the case where the code rate of the current frame of the base layer is greater than the average code rate of the C frames of the base layer before the current frame of the base layer, it is determined that the scene change of the current frame of the base layer relative to the previous frame of the base layer is large, the motion is intense, and it is a scene change frame, so it is necessary to adjust the quantization parameter of the current frame of the enhancement layer, that is, it is necessary to reduce the quantization parameter of the current frame of the enhancement layer to increase the code rate, thereby improving the encoding quality.

[0080] In some embodiments of the present application, in the case of using time domain prediction, the above S401 to S405 are used to adaptively increase the code rate of some scene change frames (the current frame of the enhancement layer corresponds to the current frame of the base layer, and the code rate of the current frame of the base layer is greater than the average code rate of the previous C frames of the base layer, and the current frame of the enhancement layer is an important frame) by using a sliding window algorithm, to reduce the influence of error propagation, and to further improve the encoding quality of the video.

[0081] In some embodiments of the present application, the code rate of the current frame base layer corresponding to the current frame enhancement layer of the to-be-encoded enhancement layer sequence is obtained when the to-be-encoded enhancement layer sequence uses temporal prediction, and the code rate of the C frame base layer before the current frame base layer (the code rate of the C frame base layer includes the code rate of each frame base layer in the C frame base layer) is obtained. The target number of the code rate of the C frame base layer that is less than the code rate of the current frame base layer is determined. When the target number is less than or equal to a number threshold (the number threshold is determined according to actual conditions, which is not limited here), the current frame enhancement layer is encoded based on a first quantization parameter. When the target number is greater than the number threshold, the quantization parameter of the current frame enhancement layer is updated from the first quantization parameter to a second quantization parameter. The current frame enhancement layer is encoded based on the second quantization parameter, and the second quantization parameter is less than the first quantization parameter.

[0082] It can be understood that the number of the code rate of the C frame base layer that is less than the code rate of the current frame base layer determines whether the current frame base layer has a larger scene change relative to the previous frame base layer, thereby determining whether to adjust the quantization parameter of the current frame enhancement layer. Specifically, when the number of the code rate of the C frame base layer that is less than the code rate of the current frame base layer is less than or equal to a number threshold, it is determined that the scene change of the current frame base layer relative to the previous frame base layer is not large, and the motion is not intense, which is not a scene change frame, so it is not necessary to adjust the quantization parameter of the current frame enhancement layer. When the number of the code rate of the C frame base layer that is less than the code rate of the current frame base layer is greater than the number threshold, it is determined that the scene change of the current frame base layer relative to the previous frame base layer is large, and the motion is intense, which is a scene change frame, so it is necessary to adjust the quantization parameter of the current frame enhancement layer, that is, it is necessary to reduce the quantization parameter of the current frame enhancement layer to improve the code rate, thereby improving the encoding quality.

[0083] In some embodiments of the present application, the frame type of the current frame base layer corresponding to the current frame enhancement layer is obtained when the to-be-encoded enhancement layer sequence uses temporal prediction, and then when the frame type of the current frame base layer is a key frame (I frame), the quantization parameter of the current frame enhancement layer is updated from a first quantization parameter to a second quantization parameter. The current frame enhancement layer is encoded based on the second quantization parameter, and the second quantization parameter is less than the first quantization parameter. When the frame type of the current frame base layer is a non-key frame (P frame or B frame), the current frame enhancement layer is encoded based on the first quantization parameter.

[0084] It can be understood that generally the key frame is a scene change frame, so when the frame type of the current frame base layer is a key frame, it is necessary to adjust the quantization parameter of the current frame enhancement layer, that is, it is necessary to reduce the quantization parameter of the current frame enhancement layer to improve the code rate, thereby improving the encoding quality. When the frame type of the current frame base layer is a non-key frame, it is not necessary to adjust the quantization parameter of the current frame enhancement layer.

[0085] In some embodiments of this application, when temporal prediction is used for the enhancement layer sequence to be encoded, the frame type of the current frame base layer corresponding to the current frame enhancement layer, the bitrate of the current frame base layer corresponding to the current frame enhancement layer, and the bitrate of the C-frame base layer before the current frame base layer can be combined to determine whether to adjust the quantization parameters of the current frame enhancement layer. The specific adjustment can be determined according to the actual situation and is not limited here.

[0086] In some embodiments of this application, the coding quality is improved by reducing the quantization parameters (increasing the bitrate) of some scene-changing frames. Simultaneously, due to the use of temporal prediction, the improved coding quality of these scene-changing frames also improves the coding quality of subsequent frames. Furthermore, since frames with significant scene changes generally exhibit locality—meaning that no further significant scene changes occur for a short period after a major scene change—the number of enhancement frames in the sequence to be encoded that require reduced quantization parameters to improve coding quality is small. Therefore, the overall bitrate improvement of the enhancement layer sequence is relatively small, meaning the impact on the overall bitrate is minimal.

[0087] In this embodiment of the application, when LCEVC-based video encoding uses fixed quantization parameters, the first quantization parameter is determined before encoding, and the second quantization parameter can also be determined before encoding, or it can be calculated in real time based on the first quantization parameter when it is determined that the current frame enhancement layer will use reduced quantization parameter encoding; when LCEVC-based video encoding uses rate control encoding, the first quantization parameter is determined according to the corresponding rate control method, and the second quantization parameter is calculated in real time based on the first quantization parameter when it is determined that the current frame enhancement layer will use reduced quantization parameter encoding.

[0088] The second quantization parameter is calculated in real time based on the first quantization parameter. Specifically, it can be determined by the difference between the first quantization parameter and the preset value, or by the product of the first quantization parameter and the preset adjustment coefficient. It can also be calculated by other methods, which are not limited here.

[0089] In some embodiments of this application, combined with Figure 4 ,like Figure 5 As shown, the above S404 can be specifically implemented through the following S404a and S404b.

[0090] S404a. The product of the first quantization parameter and the adjustment coefficient is determined as the second quantization parameter.

[0091] The adjustment coefficient is greater than 0 and less than 1.

[0092] The adjustment coefficient can be determined according to the actual situation, and no limit is set here.

[0093] wherein the second quantization parameter can be calculated according to a formula sw2 = sw1 S0 and the first quantization parameter.

[0094] wherein sw2 is the second quantization parameter, sw1 is the first quantization parameter, and S0 is the adjustment coefficient.

[0095] S404b, updating the quantization parameter of the current frame enhancement layer from the first quantization parameter to the second quantization parameter.

[0096] In some embodiments of the present application, the product of the first quantization parameter and the adjustment coefficient is determined as the second quantization parameter, and the adjustment coefficient is greater than 0 and less than 1. By multiplying the adjustment coefficient, a certain proportion of the quantization parameter is reduced, and the second quantization parameter after the first quantization parameter is reduced can be quickly determined.

[0097] In some embodiments of the present application, the adjustment coefficient is greater than or equal to 0.5 and less than or equal to 0.8. In this way, on the one hand, the quantization effect can not be affected, and on the other hand, the code rate can be improved by reducing the quantization parameter, thereby improving the encoding quality.

[0098] In some embodiments of the present application, C is k times the size of the basic layer encoding group of pictures (GOP), and k is a positive integer.

[0099] wherein the value of k is related to the size of the GOP, the length of the to-be-encoded enhancement layer sequence, etc., and can be determined according to actual conditions, which is not limited here. For example, k can take values of 1, 2, 3, etc.

[0100] In some embodiments of the present application, C is the difference between the size of the GOP and 1.

[0101] In some embodiments of the present application, an arbitrary value of C will cause a large fluctuation in effect. C being an integer multiple or close to an integer multiple of the size of the GOP can ensure that in the case that the number of enhancement frames that need to be adjusted quantization parameters is relatively small and the improvement of the overall code rate is relatively small, the average encoding quality of the video encoding is improved.

[0102] Since the video picture content is constantly changing, there are differences between frames, and such differences will also be reflected in the relationship between the quantization parameter, the code rate and the encoding quality. The main influence is the coefficients (λ, α, a) of the above-mentioned formula (1) to formula (3) corresponding to the three relationship models. That is, some video frame contents are more sensitive to the change of the encoding code rate (or the change of the quantization parameter), while some frames are less sensitive. For example, for the ith frame and the jth frame, the change of the encoding quality brought by the same code rate ΔR (or ΔQ) is not equal, that is, Δvmaf i ≠ Δvmaf j .

[0103] In some embodiments of the present application, the average encoding quality of video encoding can be improved by appropriately reducing the quantization parameter of sensitive frames (increasing the code rate).

[0104] For example, as shown in Figure 6 The LCEVC-based enhancement layer encoding method provided in some embodiments of the present application can include the following S601-S604.

[0105] S601, for each frame of enhancement layer in the to-be-encoded enhancement layer sequence, respectively performing: first pre-encoding based on a first pre-encoding quantization parameter, determining a first encoding quality and a first code rate corresponding to the first pre-encoding, second pre-encoding based on a second pre-encoding quantization parameter, determining a second encoding quality and a second code rate corresponding to the second pre-encoding.

[0106] The first pre-encoding quantization parameter and the second pre-encoding quantization parameter are different, for example, the first pre-encoding quantization parameter is smaller than the second pre-encoding quantization parameter. The first pre-encoding quantization parameter and the second pre-encoding quantization parameter can be determined according to actual conditions, which are not limited here. One of the first pre-encoding quantization parameter and the second pre-encoding quantization parameter can be the same as the quantization parameter of the LCEVC encoding of the corresponding frame of enhancement layer (the third quantization parameter or the fifth quantization parameter described below), or both can be different from the quantization parameter of the LCEVC encoding of the corresponding frame of enhancement layer, which is not limited here.

[0107] For each frame of enhancement layer in the to-be-encoded enhancement layer sequence, the first pre-encoding quantization parameter can be the same or different; for each frame of enhancement layer in the to-be-encoded enhancement layer sequence, the second pre-encoding quantization parameter can be the same or different, which is not limited here.

[0108] S602, based on the first encoding quality, the first code rate, the second encoding quality and the second code rate of each frame of enhancement layer, determining M target frame of enhancement layer from the to-be-encoded enhancement layer sequence.

[0109] The encoding quality of each target frame of enhancement layer is more affected by the code rate than the encoding quality of other frames of enhancement layer in the to-be-encoded enhancement layer sequence except the M target frame of enhancement layer, and M is an integer greater than 1. The value of M can be determined according to actual conditions, which is not limited here, for example, it can be determined according to the length of the to-be-encoded enhancement layer sequence.

[0110] In some embodiments of the present application, the following formula (4) can be obtained based on the above formula (2).

[0111]

[0112] Wherein, vmaf1 is the first encoding quality, R1 is the first code rate, vmaf2 is the second encoding quality, and R2 is the second code rate. Therefore, the first encoding quality, the first code rate, the second encoding quality, and the second code rate corresponding to each frame of the enhancement layer are substituted into the above formula (4) respectively, that is, the degree of influence of the code rate on the encoding quality of each frame of the enhancement layer α can be calculated, and then the α of each frame of the enhancement layer is sorted to determine the M frames of the enhancement layer with the maximum α, that is, the M target frames of the enhancement layer.

[0113] S603, updating the quantization parameter of each target frame of the enhancement layer from the third quantization parameter to the fourth quantization parameter.

[0114] Wherein, the fourth quantization parameter is less than the third quantization parameter.

[0115] S604, encoding each target frame of the enhancement layer based on the fourth quantization parameter.

[0116] In some embodiments of the present application, the M target frames of the enhancement layer with greater influence of the code rate on the encoding quality (sensitive to the change of the encoding quality to the code rate) are determined from the sequence of the to-be-encoded enhancement layer, and then the quantization parameter of each target frame of the enhancement layer is reduced (the third quantization parameter is reduced to the fourth quantization parameter) to improve the code rate and further improve the encoding quality of each target frame of the enhancement layer.

[0117] In some embodiments of the present application, the other frames of the enhancement layer except the M target frames of the enhancement layer in the sequence of the to-be-encoded enhancement layer can be encoded based on the original quantization parameter, so that the average encoding quality of the video encoding is improved by reducing the quantization parameter of only a small number of target frames of the enhancement layer sensitive to the change of the encoding quality to the code rate, and the influence on the code rate is not great.

[0118] In some embodiments of the present application, some specific frames of the enhancement layer except the M target frames of the enhancement layer in the sequence of the to-be-encoded enhancement layer, which are not sensitive to the change of the encoding quality to the code rate, can be encoded by increasing the quantization parameter to reduce the code rate. Because the encoding quality of these specific frames of the enhancement layer is not greatly affected by the code rate, appropriately increasing the code rate of these specific frames of the enhancement layer has little influence on the overall encoding quality, and can offset the increased code rate of the target frames of the enhancement layer, and further improve the quantization parameter of the specific frames of the enhancement layer (reduce the code rate of the frames not sensitive to the change of the encoding quality to the code rate), so that the average encoding quality of the video encoding is improved under the condition that the overall code rate of the video encoding is basically unchanged.

[0119] In some embodiments of the present application, the above-mentioned formula (4) is combined with Figure 6 For example, the formula (4) is combined with Figure 7As shown, after S601, the LCEVC-based enhancement layer encoding method provided in some embodiments of the present application can further include S605-S607 described below.

[0120] S605, based on the first encoding quality, the first code rate, the second encoding quality and the second code rate of each frame enhancement layer, determining N specific frame enhancement layers from the to-be-encoded enhancement layer sequence.

[0121] Wherein, the degree of influence of the encoding quality of each specific frame enhancement layer on the code rate is less than the degree of influence of the encoding quality of other frame enhancement layers in the to-be-encoded enhancement layer sequence on the code rate, and N is an integer greater than 1. The value of N can be determined according to actual conditions, which is not limited here, for example, it can be determined according to the length of the to-be-encoded enhancement layer sequence.

[0122] In combination with the related description of S602 described above, after sorting the α of each frame enhancement layer, the N frame enhancement layers with the smallest α are determined as the N specific frame enhancement layers.

[0123] S606, updating the quantization parameter of each specific frame enhancement layer from the fifth quantization parameter to the sixth quantization parameter.

[0124] Wherein, the sixth quantization parameter is greater than the fifth quantization parameter.

[0125] S607, encoding each specific frame enhancement layer based on the sixth quantization parameter.

[0126] In some embodiments of the present application, by determining N specific frame enhancement layers with less encoding quality affected by the code rate (encoding quality not sensitive to code rate changes) from the to-be-encoded enhancement layer sequence, then by increasing the quantization parameter of each specific frame enhancement layer (increasing the fifth quantization parameter to the sixth quantization parameter) to reduce the code rate of each specific frame enhancement layer, but since each specific frame enhancement layer is a frame with encoding quality not sensitive to code rate changes, the impact on the encoding quality of each specific frame enhancement layer is small.

[0127] Exemplarily, assuming that M and N are both 3, and the to-be-encoded enhancement layer sequence includes 20 frame enhancement layers, then the following steps are performed on each frame enhancement layer in the 20 frame enhancement layers: based on the first pre-encoding quantization parameter, the i-th frame enhancement layer is pre-encoded to determine the vmaf1 i and R1 i of the i-th (i=0, 1, 2, 3, …, 19) frame enhancement layer, based on the second pre-encoding quantization parameter, the i-th frame enhancement layer is pre-encoded to determine the vmaf2 i and R2 i of the i-th frame enhancement layer, based on vmaf1 i and R1 ivmaf2 i and R2 i and the above formula (4), the α i , i.e. the α 0 , α 1 , α 3 ……α 19 , α 0 , α 1 , α 3 ……α 19 are sorted, the 3 frames of enhancement layers with the maximum α are determined as the target frames of enhancement layers, and the 3 frames of enhancement layers with the minimum α are determined as the specific frames of enhancement layers. Then, the quantization parameter of the target frames of enhancement layers is reduced, and the quantization parameter of the specific frames of enhancement layers is increased.

[0128] In some embodiments of the present application, the quantization parameter of the M target frames of enhancement layers in the to-be-encoded enhancement layer sequence is reduced, the quantization parameter of the N specific frames of enhancement layers in the to-be-encoded enhancement layer sequence is increased, and the other frames of enhancement layers in the to-be-encoded enhancement layer sequence are encoded based on the original quantization parameter, so as to improve the code rate of some frames of enhancement layers with sensitive encoding quality to code rate change, effectively improve the encoding quality of the some frames of enhancement layers with sensitive encoding quality to code rate change, reduce the code rate of some frames of enhancement layers with insensitive encoding quality to code rate change, and almost not affect the encoding quality of the some frames of enhancement layers with insensitive encoding quality to code rate change. In this way, the overall encoding quality (i.e. the average encoding quality) is effectively improved under the condition that the overall code rate of the to-be-encoded enhancement layer sequence is basically unchanged.

[0129] In some embodiments of the present application, the fourth quantization parameter is the product of the third quantization parameter and the first adjustment coefficient, the first adjustment coefficient is the difference between 1 and the target coefficient; and the sixth quantization parameter is the product of the fifth quantization parameter and the second adjustment coefficient, the second adjustment coefficient is the sum of 1 and the target coefficient. In this way, the increase of the code rate of the M target frames of enhancement layers and the decrease of the code rate of the N specific frames of enhancement layers can be offset to each other as much as possible, so as to effectively improve the overall encoding quality (i.e. improve the average encoding quality) under the condition that the overall code rate of the to-be-encoded enhancement layer sequence is basically unchanged.

[0130] The fourth quantization parameter can be calculated according to the formula sw4=sw3·(1-S) and the third quantization parameter, and the sixth quantization parameter can be calculated according to the formula sw6=sw5·(1+S) and the fifth quantization parameter.

[0131] Wherein, sw3 is the third quantization parameter, sw4 is the fourth quantization parameter, sw5 is the fifth quantization parameter, sw6 is the sixth quantization parameter, S is the target coefficient, (1-S) is the first adjustment coefficient, and (1+S) is the second adjustment coefficient. S is greater than 0 and less than 1; for example, S is greater than or equal to 0.2 and less than or equal to 0.5.

[0132] In some embodiments of this application, when temporal prediction is used in the enhancement layer sequence to be encoded, the quantization parameters of sensitive frames can be appropriately reduced (to increase the bit rate) through the above-described S601 to S604 to improve the average encoding quality of the video encoding; alternatively, when temporal prediction is not used in the enhancement layer sequence to be encoded, the quantization parameters of sensitive frames can be appropriately reduced (to increase the bit rate) through the above-described S601 to S604 to improve the average encoding quality of the video encoding.

[0133] In some embodiments of this application, the correlation between enhancement layer frames is not utilized without using temporal prediction, but the picture content between frames still differs, making the coding quality of some enhancement layer frames more sensitive to changes in bitrate. Therefore, the quantization parameters of some enhancement layer frames whose coding quality is greatly affected by bitrate can be adjusted to improve the overall coding quality.

[0134] In some embodiments of this application, combined with Figure 4 and Figure 6 ,like Figure 8 As shown, S608 is included before S401 and S601, and S601 can be specifically implemented by S601a.

[0135] S608. Determine whether to use time-domain prediction.

[0136] S601a. ​​When the enhancement layer sequence to be encoded does not use temporal prediction, each enhancement layer in the enhancement layer sequence to be encoded performs the following: first precoding based on the first precoding quantization parameter to determine the first coding quality and the first bit rate corresponding to the first precoding; and second precoding based on the second precoding quantization parameter to determine the second coding quality and the second bit rate corresponding to the second precoding.

[0137] Therefore, when temporal prediction is not used in the enhancement layer sequence to be encoded, the quantization parameters of frames sensitive to bitrate changes in coding quality are reduced to increase the bitrate of these frames. This effectively improves the overall coding quality (i.e., increases the average coding quality) while keeping the overall bitrate of the enhancement layer sequence relatively small. This method adjusts the quantization parameters of certain frames. Because it does not use temporal prediction and employs intra-frame coding, there is no cross-referencing between frames. Therefore, it only improves the coding quality of frames sensitive to bitrate changes, ultimately resulting in an increase in average coding quality.

[0138] In some embodiments of this application, combined with Figure 7 and Figure 8 ,like Figure 9 As shown, without using temporal prediction, this method improves the overall coding quality (i.e., increases the average coding quality) by reducing the bitrate of frames whose coding quality is insensitive to bitrate changes (by increasing the quantization parameter) and increasing the bitrate of frames whose coding quality is sensitive to bitrate changes (by decreasing the quantization parameter), while keeping the overall bitrate of the enhancement layer sequence essentially unchanged. This method adjusts the quantization parameters of certain frames, and because it doesn't use temporal prediction, there's no cross-referencing between frames. It only improves the coding quality of frames sensitive to bitrate changes, ultimately resulting in an increase in average coding quality.

[0139] Based on the same inventive concept, as an implementation of the above method, such as Figure 10 As shown, some embodiments of this application also provide an enhancement layer encoding device based on LCEVC, including: a memory 1001 configured to store a computer program; and a processor 1002 configured to, when the computer program is invoked, enable the LCEVC-based enhancement layer encoding device to implement the LCEVC-based enhancement layer encoding method provided in the above-described method embodiments, and achieve the same technical effect. Wherein:

[0140] The processor 1002 is configured to, when temporal prediction is used in the enhancement layer sequence to be encoded, obtain the bitrate of the current frame base layer corresponding to the current frame enhancement layer, and the average bitrate of the C-frame base layers preceding the current frame base layer, wherein the enhancement layer sequence to be encoded includes multiple frame enhancement layers, the current frame enhancement layer is any frame among the multiple frame enhancement layers, and the average bitrate is the average bitrate of each base layer in the C-frame base layers, where C is an integer greater than 1; if the bitrate of the current frame base layer is less than or equal to the average bitrate, encode the current frame enhancement layer based on a first quantization parameter; if the bitrate of the current frame base layer is greater than the average bitrate, update the quantization parameter of the current frame enhancement layer from the first quantization parameter to a second quantization parameter, and encode the current frame enhancement layer based on the second quantization parameter, wherein the second quantization parameter is less than the first quantization parameter.

[0141] In some embodiments of the present application, in the case of using temporal prediction for the current frame enhancement layer of the to-be-encoded enhancement layer sequence, the coding quality of the current frame is improved by reducing the quantization parameter of the current frame enhancement layer (reducing the quantization parameter can improve the code rate), and since the current frame enhancement layer uses temporal prediction (utilizing the correlation between frames), the coding quality of the subsequent multiple frames of the current frame enhancement layer (using inter-frame coding) is also relatively improved, thereby improving the average coding quality of the video coding.

[0142] Some embodiments of the present application also provide a terminal device, which comprises the above-mentioned LCEVC-based enhancement layer coding apparatus and can achieve the same technical effects. To avoid repetition, details are not described here.

[0143] The embodiments of the present application also provide a computer-readable storage medium, which stores a computer program. The computer program is executed by a processor to implement each process of the above-mentioned LCEVC-based enhancement layer coding method and can achieve the same technical effects. To avoid repetition, details are not described here.

[0144] The computer-readable storage medium can be a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0145] The present application provides a computer program product, which comprises: when the computer program product is run on a computer, the computer implements the above-mentioned LCEVC-based enhancement layer coding method.

[0146] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the above embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

[0147] In order to facilitate explanation, the above description has been made in combination with specific embodiments. However, the above exemplary discussion is not intended to exhaust or limit the embodiments to the specific forms disclosed above. Various modifications and variations can be derived according to the above teachings. The selection and description of the above embodiments are to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various different modified embodiments suitable for specific use considerations.

Claims

1. An enhancement layer coding method based on LCEVC, characterized in that, include: When temporal prediction is used in the enhancement layer sequence to be encoded, the bitrate of the current frame base layer corresponding to the current frame enhancement layer and the average bitrate of the C frame base layers before the current frame base layer are obtained. The enhancement layer sequence to be encoded includes multiple frame enhancement layers. The current frame enhancement layer is any frame in the multiple frame enhancement layers. The average bitrate is the average bitrate of each base layer in the C frame base layers, where C is an integer greater than 1. If the bitrate of the current frame base layer is less than or equal to the average bitrate, the current frame enhancement layer is encoded based on the first quantization parameter. If the bitrate of the current frame base layer is greater than the average bitrate, the quantization parameter of the current frame enhancement layer is updated from the first quantization parameter to the second quantization parameter, and the current frame enhancement layer is encoded based on the second quantization parameter. Wherein, the second quantization parameter is smaller than the first quantization parameter.

2. The method according to claim 1, characterized in that, When the bitrate of the current frame base layer is greater than the average bitrate, updating the quantization parameters of the current frame enhancement layer from the first quantization parameter to the second quantization parameter includes: If the bitrate of the current frame base layer is greater than the average bitrate, the product of the first quantization parameter and the adjustment coefficient is determined as the second quantization parameter, wherein the adjustment coefficient is greater than 0 and less than 1. The quantization parameters of the current frame enhancement layer are updated from the first quantization parameter to the second quantization parameter.

3. The method according to claim 2, characterized in that, The adjustment coefficient is greater than or equal to 0.5 and less than or equal to 0.

8.

4. The method according to any one of claims 1 to 3, characterized in that, C is k times the size of the encoded image group of the basic layer, where k is a positive integer.

5. The method according to claim 1, characterized in that, The method further includes: Without using temporal prediction, each frame enhancement layer in the sequence to be encoded performs the following operations: first precoding based on first precoding quantization parameters to determine the first coding quality and first bitrate corresponding to the first precoding; and second precoding based on second precoding quantization parameters to determine the second coding quality and second bitrate corresponding to the second precoding. Based on the first coding quality, first bit rate, second coding quality and second bit rate of each frame enhancement layer, M target frame enhancement layers are determined from the sequence of enhancement layers to be encoded. The coding quality of each target frame enhancement layer is affected by the bit rate to a greater extent than the coding quality of the first other frame enhancement layers is affected by the bit rate. The first other frame enhancement layers are the frame enhancement layers in the sequence of enhancement layers to be encoded other than the M target frame enhancement layers, where M is an integer greater than 1. The quantization parameter of each target frame enhancement layer is updated from the third quantization parameter to the fourth quantization parameter, where the fourth quantization parameter is less than the third quantization parameter. The enhancement layer of each target frame is encoded based on the fourth quantization parameter.

6. The method according to claim 5, characterized in that, The method further includes: Based on the first coding quality, first bit rate, second coding quality and second bit rate of each frame enhancement layer, N specific frame enhancement layers are determined from the sequence of enhancement layers to be encoded. The coding quality of each specific frame enhancement layer is less affected by the bit rate than the coding quality of the second other frame enhancement layers. The second other frame enhancement layers are the frame enhancement layers in the sequence of enhancement layers to be encoded other than the N specific frame enhancement layers, where N is an integer greater than 1. The quantization parameter of each specific frame enhancement layer is updated from the fifth quantization parameter to the sixth quantization parameter, where the sixth quantization parameter is greater than the fifth quantization parameter. Based on the sixth quantization parameter, each specific frame enhancement layer is encoded.

7. The method according to claim 6, characterized in that, N=M; The fourth quantization parameter is the product of the third quantization parameter and the first adjustment coefficient, where the first adjustment coefficient is the difference between 1 and the target coefficient. The sixth quantization parameter is the product of the fifth quantization parameter and the second adjustment coefficient, where the second adjustment coefficient is the sum of 1 and the target coefficient.

8. An enhancement layer coding device based on LCEVC, characterized in that, include: Memory, configured to store computer programs; The processor is configured to, when a computer program is invoked, cause the LCEVC-based enhancement layer coding apparatus to implement the LCEVC-based enhancement layer coding method according to any one of claims 1 to 7.

9. A terminal device, characterized in that, include: The LCEVC-based enhancement layer coding apparatus as described in claim 8.

10. A computer-readable storage medium, characterized in that, include: A computer program is stored on a computer-readable storage medium, which, when executed by a processor, implements the LCEVC-based enhancement layer coding method as described in any one of claims 1 to 7.

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