CN106254870B - Video encoding method, system and computer-readable recording medium using adaptive color conversion - Google Patents

Abstract

A video encoding method and system, the method includes the following steps. Receive a source video frame. Split the original video picture into a coding tree unit (coding tree unit). A coding unit (coding unit) is determined from the coding tree unit. Enable or disable a coding mode of the coding unit. If the encoding mode is enabled, it is determined whether to estimate the size of a transformation unit (transform unit) in the enabled encoding mode. The enabled encoding mode determines the encoding unit's translation unit. The size of the coding unit is NxN.

Description

Video encoding method, system and computer readable using adaptive color conversion recording medium

technical field

The present disclosure relates to video encoding and decoding methods and systems.

Background technique

The demand for high-quality images is gradually increasing. With the advent of video standards such as 4K and 8K, it is extremely necessary to improve the efficiency of video encoding and decoding. In addition, consumers expect to be able to transmit and receive high-quality images through a variety of transmission media. For example, consumers want to be able to view high-quality images on portable devices (eg, smart phones, tablet computers, notebook computers) and home TVs and computers via the Internet. Consumers also expect high-quality images to be displayed during video conferencing and screen sharing.

High Efficiency Video Coding (HEVC) H.265 provides a new standard for improving the encoding and decoding performance of video compression. Compared with the original AVC (Advanced Video Coding) standard, HEVC established by ISO/IEC JTC 1/SC 29/WG 11 MPEG (Moving Picture Experts Group) and ITU-T SG16 VCEG (Video Coding Experts Group) can reduce compression Data rate for high quality video. The AVC standard is also known as H.264.

HEVC utilizes various coding tools such as Inter prediction and Intraprediction to compress video. Inter prediction techniques utilize temporal redundancies between different video pictures of a video stream to compress video data. For example, encoded and decoded video pictures containing similar content may be used to encode the current video picture. These encoded and decoded video pictures can be used to predict the encoding region of the current video picture. In contrast, intra-prediction techniques utilize only the internal data of currently encoded video pictures to compress video data. Intra prediction techniques do not use the temporal redundancy of different video frames. For example, current video pictures are encoded using another part of the same picture. The intra-frame prediction technology includes 35 intra-frame modes, including a Planar mode, a DC mode, and 33 directional modes.

Compared with the AVC standard, the HEVC standard adopts an expansion partitioning and dividing technique for each input video picture. The AVC standard uses only macroblocks of the input video picture for segmentation during encoding and decoding. Conversely, the HEVC standard can divide the input video frame into data units and blocks of different sizes, as described below. Compared with the AVC standard, the HEVC standard provides more flexibility for the encoding and decoding procedures of dynamic, multi-detail and multi-edge video images.

Some coding tools that can improve the video coding process are also included in the HEVC standard. Such coding tools are called coding extensions. The Screen Content Coding extension (SCC extension) focuses on improving the processing performance of video screen content under the HEVC standard. The content of the screen is a video rendered by a pattern, text or animation, rather than a video scene extracted by a camera. The imaged patterns, text or animation can be dynamic or static and can be provided in video within the video scene captured by the camera. Application examples of SCC can include screen mirroring, cloud gaming, wireless display of content, displays generated during remote computer desktop access, and screen sharing (screen sharing) (eg instant screen sharing for video conferencing).

An encoding tool within the SCC is adaptive color transform (ACT). ACT is a color space transformation applied to residual pixel samples (residue pixel samples) of a coding unit (CU). For a particular color space, correlations exist for color components of a pixel of a coding unit (CU). When the correlation of color elements of a pixel is high, the pixel performing ACT can help related color elements concentrate energy by de-correlating. This way of concentrating energy can improve coding efficiency and reduce coding cost. Therefore, ACT can improve coding performance during HEVC coding.

However, during encoding, an additional rate distortion optimization (RDO) function is required to evaluate whether ACT is enabled. RDO is used to estimate the cost of rate distortion (RD). These evaluation processes may increase coding complexity and coding time. Furthermore, ACT may not be necessary when the color elements of the pixels have been decorrelated. In this case, further decorrelation procedures on color elements may not bring any benefit since the cost of performing ACT outweighs the benefits of encoding.

SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, a video encoding method is provided. The video encoding method includes the following steps. A source video frame is received. The original video picture is divided into a coding tree unit. A coding unit is determined from the coding tree unit. Enables or disables a coding mode of the coding unit. If the encoding mode is enabled, it is determined whether to estimate the size of a transform unit when the encoding mode is enabled. Determines the translation unit of the coding unit in the enabled coding mode. The size of the coding unit is NxN.

According to another aspect of the present disclosure, a video encoding system is provided. The video encoding system includes a memory and a processor. Memory is used to store a set of instructions. The processor is used to execute the set of instructions. This set of instructions includes the following steps. A source video frame is received. The original video picture is divided into a coding tree unit. A coding unit is determined from the coding tree unit. Enables or disables a coding mode of the coding unit. If the encoding mode is enabled, it is determined whether to estimate the size of a transform unit in the enabled encoding mode. Determines the translation unit of the coding unit in the enabled coding mode. The size of the coding unit is NxN.

According to another aspect of the present disclosure, a non-transitory computer-readable recording medium is provided. A non-transitory computer-readable recording medium stores a set of instructions. The set of instructions are executed by one or more processors to perform a video encoding method. This video encoding method includes the following steps. A source video frame is received. The original video picture is divided into a coding tree unit. A coding unit is determined from the coding tree unit. Enables or disables a coding mode of the coding unit. If the encoding mode is enabled, it is determined whether to estimate the size of a transform unit in the enabled encoding mode. Determines the translation unit of the coding unit in the enabled coding mode. The size of the coding unit is NxN.

In order to have a better understanding of the above-mentioned and other aspects of the present disclosure, a number of embodiments are exemplified below, and are described in detail as follows in conjunction with the accompanying drawings:

Description of drawings

1A-1J illustrate video frames and related segmentations according to several embodiments of the present disclosure.

2 illustrates a video encoder of the present disclosure.

FIG. 3 illustrates an encoding method according to an embodiment of the present disclosure.

FIG. 4 illustrates an encoding method according to another embodiment of the present disclosure.

FIG. 5 illustrates an encoding method according to another embodiment of the present disclosure.

FIG. 6 illustrates an encoding method according to another embodiment of the present disclosure.

FIG. 7 illustrates the calculation flow of IPM in non-444 chroma format.

FIG. 8 illustrates a system implementing the encoding and decoding methods of the present disclosure.

【Symbol Description】

101: Video frame (video frame)

102: coding tree unit (coding tree unit, CTU)

103: Luma coding tree block (luma coding tree block, luma CTB)

104: Cb CTB

105: Cr CTB

106, 111: related instructions

107-1, 107-2, 107-3, 107-4: Luma coding block (luma coding block, luma CB)

108: Coding unit (Coding unit, CU)

109: Cb CB

110: Cr CB

112: Luma prediction block (luma prediction block, PB)

113-1, 113-2, 113-3, 113-4: Transform block (TB)

114: Transformation unit (Transform unit, TU)

200: Video encoder

202: Frame Dividing Module

204: Inter Prediction enabling adaptive colortransformation Module

206: Inter Prediction disabling ACT Module

208: Picture register (Frame Buffer)

210: Mode Decision Module

212: Intra Prediction enabling ACT Module (Intra Prediction enabling ACT Module)

214: Intra Prediction disabling ACT Module

216, 218: Summing Module

220: Switcher

222: Adaptive Color Conversion (ACT) module

224: CCP, Transform, and Quantization Module

226: Entropy Coding Module

228: Inverse CCP, Transform, and Quantization Module (Inverse CCP, Transform, and QuantizationModule)

230: Switcher

232: Inverse ACT Module (Inverse ACT Module)

300, 400, 500, 600, 700, 800: Coding method

304: Component correlation analysis

306: Rough mode decision

308: end

310: Rate distortion optimization mode decision (RDO mode decision)

311: Judging whether the chroma format is non-444 (non-444)

312: Judgment of whether the CU size is smaller than the critical value T1

314: TU size decision

316: chroma mode decision

402: Judgment of whether the CU size is smaller than the critical value T2

702: Non-transitory computer readable media

704: Processor

Detailed ways

Exemplary embodiments will be described in detail below in conjunction with the accompanying drawings. In the drawings described below, unless otherwise indicated, the same reference numbers in different drawings represent the same or similar elements. The examples presented below are not representative of all implementations of the present disclosure. In fact, these embodiments are merely examples of systems and methods corresponding to the claims.

1A-1J illustrate a video picture and its associated segmentation according to embodiments of the present disclosure.

FIG. 1A shows a video frame 101 . The video picture 101 includes several pixels. The video picture 101 is divided into a number of coding tree units (CTUs) 102 . The size of each CTU 102 is determined according to L vertical samples and L horizontal samples (LxL). Each sample corresponds to a pixel value at a different pixel location of the CTU. For example, L can be 16, 32, or 64. The pixel position may be the position of the pixel at the position where the CTU is located or the position between the pixels. When the pixel locations are locations between pixels, the pixel value may be an interpolated value of one or more pixels near the pixel location. Each CTU 102 includes a luma coding tree block (luma CTB), a chroma coding tree block (chroma CTB), and associated syntax.

FIG. 1B shows that several CTBs may be included in one CTU 102 of FIG. 1A. For example, CTU 102 may include luma CTB (luma CTB) 103, chroma CTB (chroma CTB) (including Cb CTB 104Cr CTB 105). The CTU 102 may also include associated syntax 106 . The Cb CTB 104 is a bluedifference chroma component CTB (bluedifference chroma component CTB), which represents the change of the CTB in blue. The Cr CTB 105 is a red difference chroma component CTB (red difference chroma component CTB), which represents the change of the CTB in red. The related description 106 includes information on how the luma CTB 103 , Cb CTB 104 and Cr CTB 105 are encoded, as well as further partitioning of the luma CTB 103 , Cb CTB 104 and Cr CTB 105 . The size of CTB 103 , Cb CTB 104 and Cr CTB 105 may be the same as the size of CTU 102 . Alternatively, the size of luma CTB 103 may be the same as the size of CTU 102 , but the size of Cb CTB 104 and Cr CTB 105 may be smaller than the size of CTU 102 .

Coding tools such as intra prediction, inter prediction and others operate on coding blocks (CBs). In order to decide whether the coding procedure is to use intra-frame prediction or inter-frame prediction, the CTB can be divided into one or more CBs. The procedure for partitioning CTB into CB is based on quad-tree partitioning techniques. Therefore, the CTB can be divided into four CBs, and each CB can be further divided into four CBs. Depending on the size of the CTB, such a segmentation procedure may continue.

FIG. 1C shows the luma CTB 103 of FIG. 1B divided into one or more luma CBs 107-1, 107-2, 107-3, or 107-4. Taking a luminance CTB of 64x64 as an example, the corresponding luminance CB 107-1, 107-2, 107-3 or 107-4 may be NxN in size, for example, 64x64, 32x32, 16x16 or 8x8. In Figure 1C, the size of the luma CTB 103 is 64x64. The size of the luminance CTB 103 may be 32x32 or 16x16.

FIG. 1D illustrates an example of quadtree partitioning performed by the luma CTB 103 of FIG. 1B , wherein the luma CTB 103 is partitioned into the luma CBs 107-1, 107-2, 107-3, or 107-4 of FIG. 1C. In Figure ID, the size of the luma CTB 103 is 64x64. However, the size of the luminance CTB 103 may also be 32x32 or 16x16.

In Figure ID, the luma CTB 103 is divided into four 32x32 luma CBs 107-2. Each 32x32 luminance CB can be further divided into four 16x16 luminance CBs 107-3. Each 16x16 luminance CB can be further divided into four 8x8 luminance CBs 107-4.

A coding unit (Coding unit, CU) is used to encode the CB. A CTB may include a single CU, or be divided into several CUs. Therefore, the size of the CU can also be NxN, such as 64x64, 32x32, 16x16 or 8x8. Each CU includes one luma CB, two chrominance CBs, and related descriptions. The size of the residual CU generated in the encoding and decoding process may be the same as the size of its corresponding CU.

FIG. 1E shows a schematic diagram of CBs (luminance CB 107 - 1 of FIG. 1C ), which may be part of CU 108 . For example, CU 108 may include luma CB 107-1 and chrominance CB (Cb CB 109) and chrominance CB (Cr CB 110). The CU 108 may include associated instructions 111 . The related description 111 contains information on how to encode the luma CB 107-1, Cb CB 109 and Cr CB 110, such as a description of the quadtree information (size, position and further partitioning of the luma CB and chroma CB). Each CU 108 may have associated prediction blocks (PBs) at luma CB 107-1, Cb CB 109, and Cr CB 110. The prediction blocks are grouped into prediction units (PUs).

FIG. 1F illustrates various possible scenarios of partitioning of CB 107-1 into luminance PB 112 of FIG. 1D. The luminance CB 107-1 is, for example, divided into luminance PBs 112 according to the predictability of different regions of the luminance CB 107-1. For example, luminance CB 107-1 may include a single luminance PB 112 that is the same size as luminance CB 107-1. Alternatively, the luminance CB 107-1 may be divided into two even luminance PBs 112 vertically or horizontally. Or the luminance CB 107-1 may be divided into four luminance PBs 112 vertically or horizontally. It should be noted that FIG. 1F is only an example. Any way of partitioning into PBs under the HEVC standard is within the scope of this disclosure. The manner in which the luminance CB 107-1 is divided into the luminance PB 112 shown in FIG. 1F is mutually exclusive. For example, in the intra prediction mode of HEVC, CBs of 64x64, 32x32 and 16x16 may be partitioned into a single PB with the same size as the CB. However, an 8x8 CB may be split into a single 8x8 PB or four 4x4 PBs.

Once intra-frame prediction or inter-frame prediction is used, the residual signal generated by the difference between the prediction block and the source video image block is converted to another domain for further discrete cosine transform (discrete cosine transform, DCT) or discrete sine transform (discrete sine transform, DST) encoding. To provide these transformations, each CU or each CB needs to utilize one or more transform blocks (TBs).

1G illustrates how the luminance CB 107-1 of FIG. 1E or FIG. 1F is divided into different TBs 113-1, 113-2, 113-3, and 113-4. If luminance CB 107-1 is a 64x64 CB, TB 113-1 is a 32x32 TB, TB 113-2 is a 16x16 TB, TB 113-3 is an 8x8 TB, and TB 113-4 is a 4x4 TB. The luminance CB 107-1 can be divided into 4 TBs 113-1, 16 TBs 113-2, 64 TBs 113-3, and 256 TBs 113-4. One luminance CB 107-1 may be divided into TBs 113 of the same size or TBs 113 of different sizes.

The procedure for splitting CBs into TBs is based on quad-tree splitting. Thus, a CB can be partitioned into one or more TBs, where each TB can be further partitioned into 4 TBs. Such a segmentation procedure may continue depending on the size of the CB.

1H illustrates a quadtree partition of luma CB 107-1 of FIG. 1E or FIG. 1F, which is partitioned into TBs 113-1, 113-2, 113-3, or 113-4 of FIG. 1G using various partitioning methods. In FIG. 1H, the size of luminance CB 107-1 is 64x64. However, the size of the luminance CB 107-1 may also be 32x32 or 16x16.

In Figure 1H, the luminance CB 107-1 is divided into four 32x32 TBs 113-1. Each 32x32 TB can be further divided into four 16x16 TBs 113-2. Each 16x16 TB can be further divided into four 8x8 TB113-3. Each 8x8 TB can be further divided into four 4x4 TBs 113-4.

TB 113 is then followed by conversion to DCT or any HEVC standard. Transform units (TUs) summarize TB 113. One or more TBs are employed by each CB. CBs form individual CUs. Therefore, the structure of the translation unit (TU) is different for different CUs 108 and is determined by the CUs 108 .

FIG. 1I depicts TBs 113-1, 113-2, 113-3, and 113-4 of various partitions of TU 114. Each TU summarizes the TB partitioned in Figure 1G or Figure 1H. A 32x32 TU 114 may employ a single 32x32 TB 113-1, or one or more 16x16 TB 113-2, 8x8 TB 113-3, or 4x4 TB 113-4. For a CU employing HEVC inter-prediction, the TU may be larger than the PU, so that the TU may contain PU boundaries. However, for a CU employing HEVC intra-prediction, the TU may not cross PU boundaries.

FIG. 1J depicts a quadtree partition of the TU 114 of FIG. 1I utilizing the various TBs 113-1, 113-2, 113-3, or 113-4 of FIG. 1I. In Figure 1J, the dimensions of TU 114 are 32x32. However, the size of the TU can be 16x16, 8x8, or 4x4.

In Figure 1J, TU 114 is divided into one 32x32 TB 113-1 and four 16x16 TBs 113-2. Each 16x16 TB can be further divided into four 8x8 TBs 113-3. Each 8x8 TB can be further divided into four 4x4 TBs 113-4.

The CTU, CTB, CB, CU, PU, PB, TU, or TB described in this disclosure may include any feature, size, and property of the HEVC standard. The segmentation described in Figures 1C, 1E and 1F can also be applied to Chroma CTB (Cb CTB 104), Chroma CTB (Cr CTB 105) and Chroma CB (Cb CB 109), Chroma CB (Cr CB 110) .

FIG. 2 illustrates a video encoder 200 performing the encoding method of the present disclosure. Video encoder 200 may include one or more additional components that provide additional encoding functions of HEVC-SCC, such as palette mode, sample adaptive offset, and deblocking filtering ( de-blocking filtering). Furthermore, the present disclosure contemplates the intra-prediction mode of ACT and other encoding modes, such as the inter-prediction mode of ACT.

The video encoder 200 receives an input source video frame. The input original video frame is first input to the Frame Dividing Module 202 . The frame division module 202 divides the original video frame into at least one source CTU (source CTU). The original CU (source CU) is then obtained from the original CTU. The size of the original CTU and the size of the original CU are determined by the picture segmentation module 202 . Next, encoding is performed on a CU-by-CU basis. After the original CU is output by the screen segmentation module 202, it is input to the Inter Prediction enabling ACT module (Inter Predictionenabling adaptive color transformation Module) 204, the Inter Prediction disabling ACT Module (InterPrediction disabling ACT Module) 206, and the intra prediction enabling ACT module (Intra Predictionenabling ACT Module) 212 and Intra Prediction disabling ACT Module 214 .

The original CU of the input picture is encoded by the inter prediction enabled ACT module 204, which utilizes inter prediction techniques and enables adaptive color conversion (ACT) to determine a prediction of an original CU from the input picture. The original CU of the input picture is also encoded by the inter prediction disabled ACT module 206, which utilizes inter prediction techniques and does not enable adaptive color conversion (ACT) to determine the prediction of an original CU from the input picture (ie, disable ACT).

The reference CU stored in the frame buffer 208 may be used for inter prediction. The original PU and PB are also obtained from the original CU, and use the inter prediction procedure for the ACT module 204 for inter prediction and the ACT module 206 for inter prediction to be disabled. Inter-frame prediction utilizes regions of a video picture at different times for motion detection. The coded inter-prediction CUs of the inter-prediction-enabled ACT module 204 and the inter-prediction-disabled ACT module 206 are predetermined for the highest picture quality. The coded inter-predicted CU is then input to Mode Decision Module 210.

The original CU of the input picture is also encoded by the intra-prediction enabled ACT module 212, which utilizes intra-prediction techniques and enables adaptive color conversion (ACT) to determine a prediction of an original CU from the input picture.

The original CU of the input picture is also encoded by the intra-prediction disabled ACT module 214, which utilizes intra-prediction techniques and does not enable adaptive color conversion (ACT) to determine the prediction of an original CU from the input picture (ie, disables ACT).

The intra-prediction-enabled ACT module 212 and the intra-prediction-disabled ACT module 214 may use the original CU of the same picture stored in the picture register 208 when performing intra-prediction. The original PU and PB are also obtained from the original CU, and use the intra-prediction procedure for intra-prediction-enabled ACT module 212 and intra-prediction-disable ACT module 214. The coded intra-predicted CU is predetermined for the highest picture quality. The encoded intra-prediction CUs output from the intra-prediction-enable ACT module 212 and the intra-prediction-disable ACT module 214 are input to the mode decision module 210 .

In the mode decision module 210 , the cost of encoding the original CU is compared with the quality of the predicted CU by using inter prediction enabled ACT, inter prediction disabled ACT, intra prediction enabled ACT, and intra prediction disabled ACT. According to the result of the comparison, the prediction CU of which coding mode (for example, an inter-frame prediction CU or an intra-frame prediction CU) is determined. The selected predicted CUs are then passed to Summing Modules 216 , 218 .

In the summing module 216, the selected predicted CU is subtracted from the original CU to provide a residual CU (residual CU). The switch 220 switches to position A if the selected prediction CU is from one of the inter-prediction-enabled ACT module 204 and the intra-prediction-enabled ACT module 121 . At position A, the remaining CUs are input to the ACT Module 222 and then to the CCP, Transform, and Quantization Module 224 . However, if the predicted CU that has been selected is from one of the inter-prediction-disable ACT module 206 and the intra-prediction-disable ACT module 214, the switch 220 switches to position B. In position B, the ACT block 222 is skipped and not executed during the encoding process. The remaining CUs are input directly from the summation module 216 to the CCP, transform and quantization module 224 .

At ACT module 222, adaptive color transform is performed on the remaining CUs. The output of the ACT module 222 is routed to the CCP, conversion and quantization module 224 .

The CCP, transform and quantization module 224 performs cross component prediction (CCP), transforms (eg, Discrete Cosine Transform (DCT) or Discrete Sine Transform (DST)), and quantization of the remaining CUs. The output of the CCP, transform, and quantization module 224 is connected to an entropy coding module (Entropy Coding Module) 226 and an inverse CCP, transform, and quantization module (Inverse CCP, Transform, and Quantization Module) 228 .

The entropy encoding module 226 performs residual entropy encoding. For example, Context Adaptive Binary Arithmetic Coding (CABAC) may be performed to encode the remaining CUs. Any other entropy encoding process provided by HEVC can be performed in the entropy encoding module 226 .

After performing entropy encoding, the encoded bitstream of the CU of the input video picture is output from the video encoder 200. The output encoded bitstream may be stored in a memory, broadcast over a transmission line or network, provided to a display, or the like.

In the inverse CCP, transform and quantization module 228, the inverse of the CCP, transform and quantization module 224 is performed to determine the remaining CUs to provide a reconstructed remaining CU.

The switch 230 switches to position C if the selected prediction CU is from the inter-prediction-enabled ACT module 204 or the intra-prediction-enabled ACT module 212 . At position C, the reconstructed remaining CU is input to Inverse ACT Module 232 and then to Summing Module 218 . However, if the predicted CU that has been selected is from the inter-prediction-disable ACT module 206 or the intra-prediction-disable ACT module 214, the switch 230 switches to position D. In position D, the inverse ACT block 232 is skipped and not executed, and the reconstructed remaining CUs are input directly to the summing block 218 .

Inverse operation The ACT module 232 performs the inverse operation of the adaptive color conversion of the ACT module 232 on the reconstructed remaining CUs. The output of the inverse ACT block 232 is input to the summing block 218 .

In the summation module 218, the selected predicted CU from the mode decision module 210 is added to the reconstructed remaining CUs to provide a reconstructed source CU (reconstructed source CU). The reconstructed original CU is then stored in the picture register 208 for use in inter-prediction and intra-prediction of other CUs.

The encoding methods 300 , 400 and 500 described below are performed within the intra-prediction enabled ACT module 212 . The coding methods 300, 400 and 500 can improve coding efficiency and coding time.

The inter-prediction-enabled ACT module 204, the inter-prediction-disabled ACT module 206, the intra-prediction-enabled ACT module 212, and the intra-prediction-disabled ACT module 214 are not limited to being arranged in parallel. In one embodiment, the inter prediction enabled ACT module 204, the inter prediction disabled ACT module 206, the intra prediction enabled ACT module 212, and the intra prediction disabled ACT module 214 may be arranged in order. The arrangement of the inter prediction enabled ACT module 204, the inter prediction disabled ACT module 206, the intra prediction enabled ACT module 212, and the intra prediction disabled ACT module 214 may vary.

FIG. 3 illustrates an encoding method 300 for determining whether TU size evaluation needs to be performed in an ACT enabled intra prediction encoding process according to an embodiment of the present disclosure. More specifically, the encoding method 300 utilizes a threshold calculation on the size of the CU to decide whether to perform estimation of the size of the TU.

In step 304, a component correlation analysis is performed on an original CU to determine whether the ACT encoding mode of the CU needs to be enabled. The correlation of the color components of each pixel within the CU is analyzed. In each pixel, the correlation of the color components is compared with a pixel correlation threshold to analyze whether the correlation is higher, equal to or lower than the pixel correlation threshold.

In a CU, the total number of pixels above the pixel correlation threshold is calculated, wherein pixels equal to the pixel correlation threshold are also counted as being above the pixel correlation threshold. The total number of pixels is then compared to a CU correlation threshold.

If the total number of pixels is below the CU correlation threshold, it is determined that the color components of the CU have low correlation. Therefore, the CU does not need ACT, so the flow proceeds to step 308, and ACT is disabled in the coding of the CU.

However, if the total number of pixels is higher than the CU correlation threshold, it is determined that the color components of the CU have high correlation. In this case, ACT is the component correlation needed to remove the individual pixels of the CU. When high correlation is confirmed, ACT is enabled and the flow proceeds to step 306 . At step 306, with intra prediction enabled ACT, a rough mode decision is made.

The correlation analysis of step 304 may further or alternatively be performed according to the colorspace of the CU. For example, in step 304, the color components of the pixels within the CU may be analyzed, and the color space of the CU may be determined. The color space can be determined as a red, green and blue (RGB) space or a luminance and chrominance (YUV) space.

When it is determined that the color space is the RGB color space, the flow proceeds to step 306 . At step 306, with intra prediction enabled ACT, a rough mode decision is made. Since RGB pixel components usually have high correlation, ACT is required to remove the correlation of the components of each pixel within the CU to isolate the pixel energy into a single component.

On the other hand, when the color space is determined to be the YUV color space, the flow proceeds to step 308, and ACT is disabled. This is because YUV pixel components generally have low correlation, and most pixel energy is stored in a single pixel component. It is not necessary to enable ACT on YUV pixel components since further de-correlation of CU pixel components does not yield additional coding benefits.

In the intra-prediction-enabled ACT module 212 , when the encoding method 300 disables ACT, the encoding mode of the intra-prediction-enabled ACT is disabled, and the intra-prediction-enabled ACT module 212 does not output predictions to the mode decision module 210 .

In the inter prediction enabled ACT module 204 , when the inter prediction encoding is disabled ACT, the encoding mode of the inter prediction enabled ACT is disabled, and the inter prediction enabled ACT module 204 does not output predictions to the mode decision module 210 .

In step 306, a rough mode decision is made with ACT enabled for intra prediction. The rough mode decision may be a cost-based mode decision. For example, in a rough mode decision, the selected encoding mode of low complexity cost may be decided to make the decision quickly, which typically has the highest quality and lowest encoding cost.

In step 310, a rate distortion optimization mode decision (RDO mode decision) is performed in the ACT-enabled encoding mode. Here, when ACT, CCP, transform, quantization, and entropy encoding are performed, the variation of the original video and the bit cost of the encoding mode are calculated. Variation can be obtained by an error calculation, eg mean squared error (MSE). Next, the ROD analysis selects the coding mode with the lowest coding cost and the highest coding quality.

For example, in the intra prediction enabled ACT module 212, 35 intra prediction modes (IPMs) are available for encoding. The intra-prediction-enabled ACT module 212 uses a simple, low-complexity coding cost determination method to select the lowest coding cost and highest coding quality from these intra-prediction modes in the rough mode determination in step 306 . For example, the sum of absolute transform distortion (SATD) cost can be used to determine the low complexity coding cost of each IPM. For example, the selection of the lowest coding cost and the highest partial code quality may be to choose 3 IPMs or to choose 8 IPMs. Intra prediction enabled ACT module 212, in the RDO mode decision of step 310, makes an RDO mode decision for each selected IPM. When ACT, CCP, transformation, quantization, and entropy encoding are performed, the variation of the original video for each selected IPM and the bit cost of encoding are calculated. Variation can be obtained by an error calculation, eg mean squared error (MSE). Next, the IPM with the lowest coding cost and the highest coding quality is selected from the selected IPMs by ROD analysis.

Variations of the flow described above with respect to enabling the ACT module 212 for intra-prediction may also be performed to enable the ACT module 204 for inter-prediction. For example, when the inter prediction enabled ACT module 204 performs the encoding method 300, at step 306, a rough mode determination of the best inter prediction for temporally adjacent video frames is made, which provides the lowest encoding cost and highest encoding quality. At step 310, an RDO mode decision for inter prediction is made. Here, when ACT, CCP, transform, quantization, and entropy coding are performed, the variation and coding bit cost of the inter-predicted original video are calculated. Variation can be obtained by error calculation (error calculation), eg mean squared error (MSE). Next, the ROD analysis selects the inter prediction with the lowest coding cost and the highest coding quality.

In step 312, the CU size of the currently processed CU is calculated. The size of a CU may be NxN, where N may be 4, 8, 16, 32, or 64. The N value of CU is compared with the critical value T1. The threshold value T1 can be 4, 8, 16, 32 or 64. According to the comparison result, it is determined whether the size of the CU is smaller than the threshold value T1, and thereby the size of the conversion unit to be activated in the coding mode is estimated. If the CU size is smaller than the threshold value T1, the process proceeds to step 314 to make a TU size decision. However, if the CU size is equal to or greater than the threshold value T1, the flow proceeds to step 316 and the TU size determination step of step 314 is skipped. At step 312, when the CU size is greater than the threshold T1, the TU size for the CU may be greater than the threshold T1. If the CU size CU is equal to or greater than the threshold T1, the TU quadtree structure can be determined as the largest possible TU size. For example, when the CU size is equal to or greater than the threshold T1, for a CU with a size of 64x64, four 32x32 TUs can be determined. In another embodiment, when the CU size is equal to or greater than the threshold T1, for a 32x32, 16x16, 8x8 or 4x4 CU, the TU may be the same size as the CU. For example, if the size of the CU is 32x32, the corresponding PU size may be 32x32.

Since TU size determination is time consuming and increases encoding cost, step 312 may improve encoding time and efficiency. Therefore, if the determination of the TU size can be omitted, the coding cost, that is, time can be saved. Furthermore, the CU size equal to or greater than the threshold T1 indicates that the content of the CU is not complicated. For example, a CU size larger than the threshold T1 may indicate that the video image has a large area without borders, dynamic or complex images. Therefore, the determination of the TU size may not need to be performed to efficiently perform encoding of CUs with high video quality.

In step 314, if the CU size is lower than the threshold T1, the TU size determination is performed. Here, the TU of the original CU is determined. Through the RDO cost estimation in step 310, the TU size is analyzed, and the ACT conversion of the CU with the highest efficiency and high video quality has been obtained. For example, TU sizes of 4x4, 8x8, 16x16, and 32x32 can be analyzed. When the TU size that can obtain the most efficient ACT conversion is determined, the TU size is selected for the ACT conversion of the CU and step 316 is entered. The selected TU size is used as the optimal TU quadtree size.

At step 316, a chroma mode decision is made. The determination of the chroma mode is performed according to the determination of the prediction mode in step 310, and the determined prediction mode is used to make the chroma prediction (chroma prediction) to generate the chroma PU (chroma PU) and the corresponding chroma TU (chroma TU). The TUs determined from step 312 or step 314 may also be used to generate chroma TUs. The chroma TU is also subsampled according to the chroma format. Therefore, in one embodiment, when the chroma format is 4:2:0 and the size of the luma TU is 32x32, the determined chroma TU is a 16x16 chroma TU.

At step 308, the process of selecting the best intra-prediction mode and selecting the best TU quadtree size of the intra-prediction-enabled ACT module is complete. Prediction and RDO costs have been generated and input to the mode decision module 210 for comparison with the RDO costs input to the mode decision module 210 by other prediction modules. For example, inter-prediction-enabled ACT module 204 may generate prediction and RDO costs for ACT-enabled CUs and input the predicted CU and RDO costs to mode decision module 210 . Inter-prediction-disable ACT module 206 and intra-prediction-disable ACT module 214 also generate predicted CU and RDO costs and input their respective predicted CU and RDO costs to mode decision module 210 . The mode decision module 210 compares the predicted CU and RDO costs input by the inter prediction enabled ACT module 204, the inter prediction disabled ACT module 206, the intra prediction enabled ACT module 212, and the intra prediction disabled ACT module 214, and determines the predicted CU and RDO costs to be input to The predicted CUs of the modules 216, 218 are summed.

FIG. 4 illustrates an encoding method 400 according to another embodiment of the present disclosure, which determines whether ACT needs to be enabled according to another embodiment of the present disclosure. More specifically, the encoding method 400 utilizes a threshold calculation regarding the size of the CU and the determination of the correlation of the color components of the CU pixels. ACT can be enabled or disabled based on threshold calculations. Elements with the same reference numerals may refer to the foregoing related descriptions.

At step 304, a component correlation analysis is performed on the original CU to determine whether ACT needs to be enabled or disabled. Step 304 is as described for the encoding method 300 . If the correlation of the color components of the CU is high, ACT is enabled and the flow proceeds to steps 306, 310, 314, 316 and 308 (same as the encoding step 300 described above). However, if the correlation is low, the flow proceeds to step 402 .

In step 402, the size of the currently processed CU is determined. As before, the CU size is NxN, where N can be 4, 8, 16, 32, or 64. The N value of the CU is compared with the critical value T2 to compare whether the CU size is smaller than the critical value T2. The threshold value T2 can be 4, 8, 16, 32 or 64. If the CU size is less than the threshold value T2, ACT is enabled and the flow proceeds to step 310, as in the RDO mode determination of step 310 of the encoding method 300. However, if the CU size is equal to or greater than the threshold value T2, the flow proceeds to step 308 and ACT is disabled.

In the inter prediction enabled ACT module 204, when ACT is disabled in the encoding method 400, the output of the inter prediction enabled ACT module 204 is the inter prediction CU without ACT applied. Thus, in this case, the CU output by the inter-prediction enabled ACT module 204 is the same as the output of the inter-prediction disabled ACT module 206 . Likewise, in the intra-prediction-enabled ACT module 212, when ACT is disabled in the encoding method 400, the output of the intra-prediction-enabled ACT module 212 is the intra-prediction CU without ACT applied. Thus, in this case, the output CU of the intra-prediction-enabled ACT module 212 is the same as the output of the intra-prediction-disabled ACT module 214 .

Since the size of the CU is the same or larger than the threshold T2, it means that the content of the CU is not complicated, step 402 can improve the coding time and coding efficiency. A CU size larger than the critical value T2 may indicate that the video image has a large area without borders, dynamic or complex images. In combining color components that have been sufficiently decorrelated, ACT may not be required in order to encode the CU efficiently.

5 illustrates an encoding method 500 according to another embodiment of the present disclosure that determines whether ACT needs to be enabled and whether TU size estimation needs to be performed through two threshold calculations, according to another embodiment of the present disclosure. More specifically, encoding method 500 uses a first threshold calculation with respect to CU size and a correlation decision for CU pixel color components used to determine whether to enable ACT. The encoding method 500 also uses a second threshold calculation with respect to the size of the CU to decide whether or not estimation of the size of the TU needs to be performed. Elements with the same reference numerals may refer to the foregoing related descriptions.

At step 304, a component correlation analysis is performed on the original CU to determine whether ACT needs to be enabled or disabled. Step 304 is as described for the encoding method 300 . If the correlation of the color components of the CU is high, ACT is enabled and the flow proceeds to step 306 for rough mode determination and RDO mode determination in step 310 . Steps 306 and 310 are the same as described for the encoding method 300 above. However, if the correlation is low, the flow proceeds to step 402 .

In step 402, the size of the currently processed CU is determined (as described in the encoding method 400 of FIG. 4 above). If the CU size is smaller than the threshold value T2, the ACT is enabled, and the process proceeds to step 310 for RDO mode determination. However, if the CU size is equal to or greater than the threshold T2, the flow proceeds to step 308 and ACT is disabled.

In the inter prediction enabled ACT module 204, when ACT is disabled in the encoding method 500, the output of the inter prediction enabled ACT module 204 is the inter prediction CU without ACT applied. Thus, in this case, the CU output by the inter-prediction enabled ACT module 204 is the same as the output of the inter-prediction disabled ACT module 206 .

Likewise, in the intra-prediction-enabled ACT module 212, when ACT is disabled in the encoding method 500, the output of the intra-prediction-enabled ACT module 212 is the intra-prediction CU to which ACT is not applied. Therefore, in this case, the output CU of the intra-prediction-enabled ACT module 212 is the same as the output of the intra-prediction-disabled ACT module 214.

At step 310, the RDO mode is determined as described in the encoding method 300 described above.

In step 312, the calculation of the size of the CU currently being processed is the same as that described in the encoding method 300, to determine whether the size of the CU is smaller than the threshold value T1. If the CU size is smaller than the threshold value T1, the process proceeds to step 314 to determine the TU size. However, if the CU size is equal to or greater than the threshold T1, the flow proceeds to step 316, and the TU size determination of step 314 is skipped. The decision process of steps 314 and 316 is the same as the encoding method 300 described above.

The thresholds T1 and T2 can be set to the same or different values.

The encoding method 500 of FIG. 5 incorporates threshold calculation to improve encoding efficiency and time. As described above, a CU size equal to or greater than the threshold T2 indicates that the content of the CU is not complex, and a large area of unbounded, dynamic or complex patterns can be expected. In combining color components that have been sufficiently decorrelated, ACT may not be required in order to encode the CU efficiently. Furthermore, after the TU size determination in step 314 is omitted, the coding cost can be saved.

6 illustrates an encoding method 600 (similar to encoding method 300) according to another embodiment of the present disclosure for determining whether TU size estimation needs to be performed in an ACT-enabled intra prediction procedure according to another embodiment of the present disclosure. More specifically, the coding method 600 uses a threshold calculation with respect to the CU size, and determines whether or not to perform TU size estimation according to the threshold calculation.

At step 304, a component correlation analysis is performed on the original CU to determine whether ACT needs to be enabled or disabled. Step 304 is as described for the encoding method 300 . If the correlation of the color components of the CU is high, ACT is enabled and the flow proceeds to step 306 for rough mode determination and RDO mode determination in step 310 . Steps 306 and 310 are the same as described for the encoding method 300 above. However, if the correlation in step 304 is low, or the color space is determined to be the YUV color space, the encoding mode of ACT is enabled and step 310 is directly entered, but the rough mode determination in step 306 is not performed. Here, for low-correlation pixel components or YUV color spaces, ACT is still enabled to confirm that decorrelation of pixel components may yield additional coding benefits.

At step 310, the calculation of the RDO mode decision is the same as the encoding method 300 described above.

In step 312, the calculation of the size of the CU currently being processed is the same as that described in the encoding method 300, to determine whether the size of the CU is smaller than the threshold value T1. If the CU size is smaller than the threshold value T1, the process proceeds to step 314 to determine the TU size. However, if the CU size is equal to or greater than the threshold T1, the flow proceeds to step 316, and the TU size determination of step 314 is skipped. The decision process of steps 314 and 316 is the same as the encoding method 300 described above.

The thresholds T1 and T2 can be set to the same or different values.

A decoding method that performs the reverse steps of the encoding methods 300, 400, 500, 600 can efficiently decode the video encoded by the encoding methods 300, 400, 500, 600. Therefore, the foregoing of the present disclosure suffices to understand decoding methods that perform the opposite steps of encoding methods 300 , 400 , 500 , 600 . The above content of the present disclosure is also sufficient to understand other decoding procedures required for decoding the video encoded by the encoding methods 300 , 400 , 500 , 600 .

If a large CU uses IPM as screen visual content, it may indicate that the content of this area is not complex and the size of the TU does not need to be estimated. Therefore, IPMs in non-444 chroma formats are prohibited from TU partitioning for some large CUs. FIG. 7 illustrates the calculation flow of IPM in non-444 chroma format. Steps 306 and 310 are the same as those of the encoding method 300 described above. At step 310, the RDO mode decision is calculated as in the encoding method 300 described above.

In step 311, it is determined whether the chroma format is non-444. If the chroma format is not 444, go to step 312 . If the chroma scale is not non-444, then go to step 314, and determine according to the nearest row TU size.

In step 312, the calculation of the size of the CU currently being processed is the same as that described in the encoding method 300, to determine whether the size of the CU is smaller than the threshold value T1. If the CU size is smaller than the threshold value T1, the process proceeds to step 314 to determine the TU size. However, if the CU size is equal to or greater than the threshold T1, the flow proceeds to step 316, and the TU size determination of step 314 is skipped. The decision process of steps 314 and 316 is the same as the encoding method 300 described above.

The thresholds T1 and T2 can be set to the same or different values.

FIG. 8 illustrates a system 700 implementing the encoding and decoding methods of the present disclosure. System 700 includes a non-transitory computer-readable medium 702, which may be a memory that stores array instructions. Such instructions may be executed by processor 704 . Notably, one or more non-transitory computer-readable media 702 and/or one or more processors 704 may optionally be employed to perform the encoding and decoding methods of the present disclosure.

The non-transitory computer-readable medium 702 may be any type of non-transitory computer-readable storage medium (non-transitory CRM). The non-transitory computer-readable recording medium may include a floppy disk, a flexible disk, a hard disk, a hard drive, a solid state drive, magnetic tape, any magnetic data storage medium, CD-ROM, any optical data storage medium, any physical medium with a hole pattern, dynamic random access Memory (RAM), Programmable Read Only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), Flash Erasable Programmable Read Only Memory (FLASH-EPROM), any flash memory, non-volatile NVRAM, cache, register, memory chip, cartridge and network. The computer-readable recording medium can store an array of instructions to be executed by at least one processor. Such instructions include causing a processor to perform steps or stages of the encoding and decoding methods of the present disclosure. Furthermore, one or more computer-readable recording media may be used to implement the encoding and decoding methods of the present disclosure. A "computer-readable recording medium" contains tangible objects but does not contain carrier carrier signals and transient signals.

The processor 704 may be any form of digital signal processor (DSP), application specific integrated circuit (ASIC), digital signal processing device (DSPD), programmable logic device (programmable logic device, PLD), programmable logic array (field programmable gate arrays, FPGA), controller (controller), microcontroller (micro-controller), microprocessor (micro-processor), computer or any other capable of executing Electronic components of the encoding and decoding methods of the present disclosure.

Experimental results

The experimental results of the encoding method of the present disclosure are described below.

The laboratory here uses the HEVC SCC reference model, SCM 4.0 under common test conditions (CTC). The coding performance of the coding method of the present disclosure is compared with the reference model of HEVC. The HEVC reference model took encoding time A to encode. The test encoding method of the present disclosure took to encode time B to encode. The encoding time percentage is encoding time B divided by encoding time A. The experiment can adopt the general test process of HEVC. Video can be mixed with text, images, motion pictures, mixed content, animation, and camera-extracted content. Video can be in RGB color space and YUV color space with 720p, 1080p, or 1440p quality. The experiments use full intra-frame prediction, random access and low-B prediction under lossy conditions. Full intra prediction uses information within the picture currently being compressed to compress video pictures, while random access and low-B prediction uses information from previously encoded pictures and the picture currently being compressed to compress video pictures. In the following description, low B prediction may also refer to low delay B prediction. In each experiment, encoding time and decoding time were recorded as percentages, which represented the ratio of encoding method to decoding method relative to the reference model. A positive percentage for each G/Y, B/U, and R/V component represents a bit rate coding loss relative to the original video source, and a negative percentage represents a bit rate coding gain. For example, a value of 0.1% for the G/Y component means that the encoding loss of the G/Y component of the encoded video relative to the G/Y component of the original video is 0.1%. In another example, a value of -0.1% for the G/Y component represents a coding gain of 0.1% for the G/Y component of the encoded video relative to the G/Y component of the original video.

Please refer to the encoding method 500 of FIG. 5 and Table 1 below. In the encoding method 500, the laboratory operates under the following three settings. In setting 1, both the threshold value T2 and the threshold value T1 are set to 64. In setting 2, the threshold value T2 is set to 64, and the threshold value T1 is set to 32. In setting three, the threshold value T2 is set to 64, and the threshold value T1 is set to 16. Intra prediction is a predetermined coding mode.

In setting one, when pixel components have low correlation, CUs with size greater than or equal to 64x64 are encoded without ACT enabled. CUs with sizes smaller than 64x64 are encoded in an ACT-enabled manner. Furthermore, when the CU size is larger than 64×64, step 314 of determining the TU size is omitted. In the case where the CU size is smaller than 64×64, step 314 of TU size determination is performed.

In setting two, when the pixel components have low correlation, CUs of size greater than or equal to 64x64 are encoded without ACT enabled. CUs with sizes smaller than 64x64 are encoded in an ACT-enabled manner. Furthermore, when the CU size is larger than 32×32, step 314 of determining the TU size is omitted. In the case where the CU size is smaller than 32x32, step 314 of TU size determination is performed.

In setting three, when the pixel components have low correlation, CUs with size greater than or equal to 64x64 are encoded without ACT enabled. CUs with sizes smaller than 64x64 are encoded in an ACT-enabled manner. Furthermore, when the CU size is larger than 16×16, step 314 of determining the TU size is omitted. For the case where the CU size is smaller than 16x16, step 314 of TU size determination is performed.

Table 1

As shown in Table 1, the encoding performance of Setting 1, Setting 2 and Setting 3 are improved. Setting one reduces encoding complexity by 3%, setting two reduces encoding complexity by 6%. Setting three reduces coding complexity by 9% (setting three reduces the most). Therefore, all settings can improve coding efficiency. Each setting improves encoding time and efficiency at a minimal loss of bit rate.

Please refer to the encoding method 500 and Tables 2 and 3 below. Here, the experiments are performed under full intra-frame, random access and low delay B (low delay B). In experiment 1, both the threshold value T2 and the threshold value T1 are set to 32. In experiment 2, the threshold value T2 and the threshold value T1 are both set to 16. Like the encoding method 500, in experiment 1, TU evaluation is disabled for CUs with a size greater than or equal to 32x32, and ACT is not enabled for encoding with a size greater than or equal to 32x32. In experiment two, CUs with size greater than or equal to 16x16 disabled TU estimation, and sizes greater than or equal to 16x16 were coded without ACT enabled. CUs with size less than 16x16 are encoded in ACT-enabled. The experiments are carried out under lossy condition and full frame intra block copy technology.

Table 2

As described in Table 2, in Experiment 1, all intra mode reduces coding complexity by 5%. Random access and low latency B each reduce coding complexity by 1%. The individual settings showed very low bitrate loss, with full intraframe and random access barely changing the bitrate.

In experiment two, the full intra mode reduces the coding complexity by 8%. Random access reduces coding complexity by 1%. Low latency B does not change the coding complexity. Compared with experiment 1, each mode has more bit rate loss, but the bit rate loss is still kept to a minimum (only in the decimal range of the percentage). Compared to the original video, the bitrate of the encoded video is only slightly reduced, so only a small amount of video quality is lost. Since the encoding method 500 improves encoding time, such video quality is acceptable for most applications.

table 3

As shown in Table 3, in Experiment 1 and Experiment 2, each mode does not change the bit rate in total or on average. Encoding complexity is reduced by the most ratio (1% reduction in each experiment) in full frame.

Please refer to the encoding method 500 of FIG. 5 and Table 4 below. Here, the experiments are performed under lossy condition, 4-CTU Intra block copy technology and 4:4:4 chroma mode. Intra-block copy techniques use motion vectors to copy a block from a previously coded CU to the currently coded video picture. The 4-CTU indicates the range within which the motion vector can be searched.

In experiment 1, both the threshold value T2 and the threshold value T1 are set to 32. In experiment 2, the threshold value T2 and the threshold value T1 are both set to 16. As with the encoding method 500, in Experiment 1, TU estimation is disabled for CUs of size greater than or equal to 32x32. In experiment 2, TU estimation is disabled for CUs with size greater than or equal to 16x16. In Experiment 1, ACT is enabled for CUs with size greater than 32x32, and ACT is disabled for CUs with size greater than or equal to 32x32. In experiment 2, ACT is enabled for CUs with a size smaller than 16x16, and ACT is disabled for CUs with a size greater than or equal to 16x16.

Table 4

As described in Table 4, in Experiment 1 and Experiment 2, full intra-frame, random access or low-latency B-mode are all the minimum bit rate changes. Intra-frame reduces the coding complexity the most, by 5% in experiment one and 8% in experiment two.

Please refer to the encoding method 400 of FIG. 4 and Table 5.1 and Table 5.2 below. Here, the threshold value T2 is set to 64. Therefore, when the component correlation analysis in step 304 shows that the color components of the CU have low correlation, step 402 is executed to determine whether the size of the CU is smaller than 64×64. If the CU size is less than 64x64, ACT is enabled and the RDO mode determination of step 310 is performed. If the CU size is greater than or equal to 64x64, then ACT is disabled and step 308 is entered. Experiment 1 adopts the lossy all intra encoding mode of full frame intra block copy technology (full frame intra block copy), and experiment 2 adopts the lossy full intra encoding mode of 4CTU IBC technology. The chrominance mode was chosen to be 4:4:4 in each experiment.

Table 5.1: Experiment 1

Table 5.2: Experiment 2

As shown in Table 5.1, the encoding method 400 reduces the encoding time by 1% to 3% with minimal bit rate loss under the YUV color space and full intra, lossy, full picture intra block copy technology. As shown in Table 5.2, under the full Intra, lossy, 4CTU Intra block copy technology, the encoding method 400 reduces the encoding time at a rate similar to that of experiment 1 in Table 5.1 with minimal bit loss.

Please refer to the encoding method 400 and Table 6 below. Here, the threshold value T2 is set to 64. Lossless intra encoding is performed in 4:4:4 chroma mode.

Table 6

In YUV color space, the encoding method saves 0% to 2% of encoding time.

Please refer to the encoding method 300 of FIG. 3 and Table 7 below. Here, the critical value T1 was set to 32 in the first experiment and 16 in the second experiment. Like the encoding method 300, in experiment 1, when the CU size is greater than or equal to 32x32, the TU size determination in step 314 is omitted; when the CU size is smaller than 32x32, the TU size determination in step 314 is performed. In experiment 2, when the CU size is greater than or equal to 16x16, the TU size determination in step 314 is omitted; when the CU size is smaller than 16x16, the TU size determination in step 314 is performed. The experiments performed ACT-enabled lossy full intra-coding.

Table 7

The encoding time for experiment one was saved by 3% to 6%. The encoding time for experiment two was saved by 6% to 10%. Therefore, TU size decisions are only allowed under CU sizes below 32x32 or 16x16 to help coding efficiency.

The above content is used to illustrate the technology of the present disclosure, but it is not intended to limit the content of the present invention. Modifications and adjustments of the embodiments fall within the scope of the present disclosure. For example, the disclosed embodiments include both software and hardware, but the systems and methods of the present disclosure may be implemented in hardware only.

A software developer can develop a computer program based on the methods of the present disclosure, which can be developed using various computer programming techniques. For example, program segments or program modules may be developed in Java, C, C++, assembly language, or any other programming language. One or more software segments and modules may be installed on a computer system, non-transitory computer readable medium, or existing communications software.

Furthermore, while the foregoing discloses various embodiments, the scope of the present disclosure includes equivalents, modifications, omissions, combinations (eg, between different embodiments), applications, or selections of various elements. The elements of the claims are to be construed in the broadest sense and are not limited to the content of the embodiments. Furthermore, the steps of the method may be modified (including reordering, insertion or deletion of steps). Although the present disclosure has been disclosed above in terms of preferred embodiments, it is not intended to limit the present disclosure. The scope of protection of the present disclosure should be determined by the scope defined by the appended claims.

Those skilled in the art to which the present invention pertains will also recognize other embodiments from the description of the present disclosure. The scope of the present disclosure includes various changes, implementations, and applications incorporating general knowledge. The description and the embodiments are only used as examples, and the protection scope of the present disclosure should be determined by the scope defined by the appended claims.

Claims (14)

1. A video coding method, comprising: Receive the original video picture; dividing the original video picture into a coding tree unit; determine a coding unit from the coding tree unit; a coding mode that enables adaptive color conversion of the coding unit, wherein the size of the coding unit is NxN; determining whether N is less than a first critical value; When N is less than the first threshold, determining the size of a conversion unit and determining the chroma mode of the coding unit; and When N is not less than the first threshold, the size of the conversion unit is not determined and the chroma mode of the coding unit is determined. 2. The method of claim 1, further comprising: Determine the color space of the coding unit; The determining of the color space of the coding unit includes determining whether the color space is a red, green and blue color space or a luminance and chrominance color space. 3. The method of claim 2, further comprising: If the enabled encoding mode is an adaptive color conversion enabled intra prediction mode, the cost mode determination is performed when the color space is determined to be the red, green and blue color spaces. 4. The method of claim 2, further comprising: If the enabled encoding mode is an adaptive color conversion-enabled intra prediction mode, the cost mode determination is performed when the color space is determined to be a luma and chroma color space. 5. The method of claim 2, further comprising: determining whether N is less than a second critical value; and When the color space is determined to be the luminance and chrominance color space and N is greater than or equal to the second threshold, the encoding mode of the encoding unit is disabled. 6. The method of claim 2, further comprising: determining whether N is less than the second threshold; and When the color space is determined to be the luminance and chrominance color space and N is less than the second threshold, the encoding mode is enabled, and the encoding mode enables adaptive color conversion. 7. The method of claim 2, further comprising: Determine whether N is greater than or equal to the second critical value; When the color space is determined to be the luminance and chrominance color space and N is not greater than or equal to the second threshold, the encoding mode is enabled, and the encoding mode enables adaptive color conversion. 8. The method of claim 1, further comprising: If the original video frame is non-444 and N is less than the first threshold, the size of the conversion unit is evaluated. 9. A video coding system, comprising: memory for storing group instructions; and a processor to execute the set of instructions, the set of instructions includes: Receive the original video picture; dividing the original video picture into a coding tree unit; determine a coding unit from the coding tree unit; a coding mode that enables adaptive color conversion of the coding unit, wherein the size of the coding unit is NxN; determining whether N is less than a first critical value; When N is less than the first threshold, determining the size of a conversion unit and determining the chroma mode of the coding unit; and When N is not less than the first threshold, the size of the conversion unit is not determined and the chroma mode of the coding unit is determined. 10. The system of claim 9, wherein the set of instructions executed by the processor further comprises: Determine the color space of the coding unit; The color space is judged whether it is the red, green and blue color space or the luminance and chrominance color space. 11. The system of claim 10, wherein the set of instructions for execution by the processor further comprises: Determine whether N is less than the second critical value; When the color space is determined to be the luminance and chrominance color space and N is less than the second threshold, the encoding mode is enabled, and the encoding mode enables adaptive color conversion. 12. The system of claim 10, wherein the set of instructions for processing by the processor further comprises: Determine whether N is greater than or equal to the second critical value; When the color space is determined to be the luminance and chrominance color space and N is not greater than or equal to the second threshold, the encoding mode is enabled, and the encoding mode enables adaptive color conversion. 13. The system of claim 9, wherein the set of instructions for processing by the processor further comprises: If the original video frame is non-444 and N is less than the first threshold, the size of the conversion unit is evaluated. 14. A non-transitory computer-readable recording medium for storing a set of instructions executable by one or more processors to perform a video encoding method, wherein the video encoding method comprises: Receive the original video picture; dividing the original video picture into a coding tree unit; determine a coding unit from the coding tree unit; a coding mode that enables adaptive color conversion of the coding unit, wherein the size of the coding unit is NxN; judging whether N is less than a first critical value; When N is less than the first threshold, determining the size of a conversion unit and determining the chroma mode of the coding unit; and When N is not less than the first threshold, the size of the conversion unit is not determined and the chroma mode of the coding unit is determined.

Images