KR20110049586A - Video coding method and apparatus by using tool set - Google Patents

Abstract

PURPOSE: A video coding method and apparatus by using a tool set are provided to reduce the bit quantity for encoding the additional information for indicating a selected encoding type. CONSTITUTION: Plural image encoders(120-150) encode the image of encoding unit according to plural encoding types, and an encoding type selector(160) selects one from the plural encoding types. Based on the encoding costs for a selection frequency of encoding type and/or the selected encoding type, an encoding tool set manager(110) updates the encoding tool set by determining the update of the encoding tool set.

Description

Video coding / decoding method and apparatus using tool set {Video Coding Method and Apparatus by Using Tool Set}

The present invention relates to a method and apparatus for image encoding / decoding using a tool set. More specifically, in encoding a prediction residual signal using an adaptive encoding technique, a method and apparatus for improving the compression efficiency of an image by efficiently selecting and encoding an encoding scheme or a decoding scheme using a tool set. It is about.

Advances in video compression technology have laid the foundations for more efficient use of video media. In particular, the H.264 / AVC video encoding technique improves the compression performance by about 2 times compared to the previous encoding technique. H.264 / AVC technology has a feature of coding in the time and space domain based on a hybrid coding technique.

Coding in the time domain reduces temporal redundancy of an image through motion compensation prediction from an image of a reference frame. The motion compensation prediction is determined by a correlation between a block of a reference frame and a block to be currently encoded of the current frame, that is, a motion vector, and obtains a motion vector predicted block by block. The prediction residual obtained as the difference between the predicted image and the original image is aligned in blocks, transformed into a frequency domain, and then quantized and encoded. However, when the prediction residuals in a block correlate with each other in the spatial domain, that is, only when they exist in a low frequency band, the encoding efficiency is increased by the conversion to the frequency domain, while the efficiency is low when only a few correlations are performed in the spatial domain. There is a problem losing.

In order to solve this problem, a method of encoding a prediction residual in a spatial domain without performing a frequency conversion is added to an existing method of encoding the prediction residual in a frequency domain, thereby converting the prediction residual signal into a frequency domain or for encoding. A technique for adaptively determining and encoding whether to maintain a prediction residual signal in a spatial domain has been proposed. However, this technique assumes that no conversion can be more effective than a conversion.

While this technique can provide higher coding performance when compared to H.264 / AVC coding, the pixels of prediction residuals in a block not only have low correlation in the spatial domain, but also large irregularities and small residuals are scattered irregularly. If so, there is a problem of low efficiency.

In order to solve the above problems, the present invention has a main object to reduce the amount of calculation for encoding while improving the compression efficiency by encoding the image using a coding method having a good efficiency among various coding methods.

According to an aspect of the present invention, there is provided an apparatus for encoding an image, the apparatus comprising: a plurality of image encoders encoding an image of a coding unit according to a plurality of encoding schemes included in an encoding tool set; An encoding scheme selector for selecting one encoding scheme among a plurality of encoding schemes for each coding unit and outputting image data encoded by the selected encoding scheme; A frequency memory for storing a selection frequency of an encoding scheme selected for each coding unit; And an encoding tool set manager configured to update the encoding tool set by determining whether to update the encoding tool set based on at least one of a frequency of selection of the encoding scheme and an encoding cost according to the selected encoding scheme. To provide.

According to another object of the present invention, there is provided an apparatus for decoding an image, comprising: a frequency memory for storing a selection frequency of an encoding scheme selected for each coding unit; Decoding encoding scheme index data and update data extracted from the bitstream to restore encoding scheme index and update information, and selecting an encoding scheme identified by the encoding scheme index to be restored among a plurality of encoding schemes included in the encoding toolset, An encoding tool set manager configured to output an image of a coding unit reconstructed according to a decoding scheme corresponding to a selected encoding scheme, and to update an encoding tool set based on a selection frequency and reconstructed update information; And a plurality of image decoders for reconstructing an image of a coding unit by decoding image encoded data extracted from a bitstream according to a decoding scheme corresponding to a selected encoding scheme.

According to still another object of the present invention, there is provided a method of encoding an image, the method comprising: encoding an image of a coding unit according to a plurality of encoding methods included in an encoding tool set; Selecting one encoding scheme among a plurality of encoding schemes for each coding unit and outputting image data encoded according to the selected encoding scheme; Storing a selection frequency of a coding scheme selected for each coding unit; And determining whether to update the encoding tool set based on at least one of a frequency of selection of the encoding scheme and an encoding cost according to the selected encoding scheme, thereby updating the encoding tool set. .

According to still another object of the present invention, there is provided a method of decoding an image, the method comprising: restoring encoding scheme index and update information by decoding encoding scheme index data and update data extracted from a bitstream; Selects an encoding method identified by a reconstructed encoding method index among a plurality of encoding methods included in the encoding tool set, and decodes the image encoded data extracted from the bitstream according to a decoding method corresponding to the selected encoding method to determine a coding unit. Restoring the image; Storing a selection frequency of a coding scheme selected for each coding unit; And updating the encoding tool set based on the selection frequency and the reconstructed update information.

As described above, according to the present invention, when encoding an image, a computation amount or an implementation complexity for selecting an efficient encoding scheme while selecting and encoding an efficient encoding scheme among various coding units is selected. In addition to reducing the amount of bits required to encode additional information for indicating the selected encoding scheme, the compression efficiency can be improved and the implementation of the apparatus can be simplified.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected or connected to that other component, but between components It will be understood that may be "connected", "coupled" or "connected".

The video encoding apparatus (Video Encoding Apparatus) and the video decoding apparatus (Video Decoding Apparatus) to be described later will be a personal computer (PC), notebook computer, personal digital assistant (PDA), portable multimedia player ( It may be a user terminal such as a PMP (Portable Multimedia Player), a PlayStation Portable (PSP), or a Mobile Communication Terminal, or a server terminal such as an application server or a service server, and may communicate with various devices or wired / wireless communication networks. Various devices including a communication device such as a communication modem for performing, various programs for encoding or decoding a motion vector, encoding or decoding an image, a memory for storing data, a microprocessor for executing and operating a program, and the like. Means the device.

In addition, the image encoded in the bitstream by the video encoding apparatus is real-time or non-real-time through the wired or wireless communication network, such as the Internet, local area wireless communication network, wireless LAN network, WiBro network, mobile communication network, or the like, or a cable, universal serial bus (USB: Universal) It may be transmitted to an image decoding apparatus through various communication interfaces such as a serial bus, and may be decoded by the image decoding apparatus to restore and reproduce the image.

In general, a moving picture is composed of a series of pictures, and each picture is divided into a predetermined area such as a block. When a region of an image is divided into blocks, the divided blocks are largely classified into intra blocks and inter blocks according to encoding methods. An intra block refers to a block that is encoded by using an intra prediction coding method. An intra prediction coding is performed by using pixels of blocks previously encoded, decoded, and reconstructed in a current picture that performs current encoding. A prediction block is generated by predicting pixels of a current block, which is a block to be encoded, and a difference value with pixels of the current block is encoded. An inter block refers to a block that is encoded using inter prediction coding. Inter prediction coding generates a prediction block by predicting a current block within a current picture by referring to one or more past or future pictures, and then generates a current block. This is a method of encoding the difference value with. Here, a picture referred to for encoding or decoding the current picture is referred to as a reference picture.

1 is a block diagram schematically illustrating a video encoding apparatus according to an embodiment of the present invention.

The video encoding apparatus 100 according to an embodiment of the present invention includes an encoding tool set manager 110, a plurality of video encoders, an encoding method selector 160, and a frequency memory. (Frequency Number Memory, 170).

The encoding tool set manager 110 stores the encoding tool set and updates the encoding tool set by determining whether to update the encoding tool set based on at least one of a selection frequency of the encoding scheme and an encoding cost according to the selected encoding scheme. . That is, the encoding tool set manager 110 stores an encoding tool set including a plurality of efficient encoding methods among various encoding methods available in the image encoding apparatus 100, and is stored in the frequency memory 170. Whether to replace and update some of the plurality of encoding schemes in the stored encoding toolset based on the encoding frequency when encoding the image of the coding unit according to the selection frequency of the encoding scheme and the encoding scheme selected by the encoding scheme selector 160. Determine and update the encoding toolset accordingly. The encoding tool set manager 110 will be described in detail with reference to FIG. 2 in a later process.

In an embodiment of the present invention, an encoding tool set refers to a set including information for identifying a plurality of encoding schemes. The plurality of encoding schemes refers to a limited number of encoding schemes selected from among the encoding schemes available in the image encoding apparatus 100 to compress the image with good efficiency. Although a plurality of encoding schemes included in the encoding tool set may be initially set to predetermined encoding schemes for encoding an image, they may be adaptively replaced and updated according to an encoding process.

Available encoding schemes may be set to any number and arbitrary encoding schemes under the assumption that the image encoding apparatus 100 and the image decoding apparatus to be described later are previously promised to each other. For example, the available coding schemes may be four coding schemes, such as a first coding scheme, a second coding scheme, a third coding scheme, and a fourth coding scheme, as shown in FIG. 3.

Here, the first encoding method refers to a method of encoding a prediction residual in a frequency domain when encoding an image, and the second encoding method refers to a method of encoding a prediction residual in a spatial domain when encoding an image. The encoding method refers to a method of encoding an additional prediction residual in a frequency domain when encoding an image, and the fourth encoding method refers to a method of encoding an additional prediction residual in a spatial domain when encoding an image.

In an embodiment of the present invention, the additional prediction refers to further predicting and further reducing the prediction residual to further remove temporal or spatial redundancy remaining in the prediction residual generated by the primary prediction. As the additional prediction, various additional predictions, such as additional prediction from a previous reference picture, additional prediction using neighboring blocks of the current block, additional prediction using vector quantization, and additional prediction using representative block selection, may be used based on the motion vector. Accordingly, when each of these various additional predictions is used, the number of available coding schemes may also increase according to the number of additional predictions used.

However, the types of encoding schemes shown in FIG. 3 are merely exemplary, and in one embodiment of the present invention, the plurality of encoding schemes is not limited to the example illustrated in FIG. 3, and various other encoding schemes may be used. .

Referring back to FIG. 1, a plurality of image encoders encode an image of a coding unit according to a plurality of encoding schemes included in an encoding tool set. That is, the plurality of image encoders encode the image of the coding unit according to each of the plurality of encoding schemes included in the encoding tool set to generate image encoded data for each encoding scheme. The plurality of image encoders may be configured in the image encoding apparatus 100 more than the number of encoding methods included in the encoding tool set.

The plurality of image encoders may be configured with the number of encoding methods available to the image encoding apparatus 100. For example, when the encoding scheme available as described above with reference to FIG. 3 is the first to fourth encoding schemes, the first image encoder 120 to the fourth image encoder 150 illustrated in FIG. Each of the first and fourth encoding methods may be an encoder for encoding an image.

In this case, the first image encoder 120 may include a predictor, a subtractor, a transformer and a quantizer, and an encoder, and may include an inverse quantizer and an inverse transformer. An inverse transformer and inverse quantizer, an adder, a deblocking filter, a memory, and the like may further be included. Here, the predictor generates a predicted block by inter-prediction or intra-prediction of the current block, the subtractor generates a residual block by subtracting the current block and the predictive block, and the transformer and the quantizer generate a residual block. The quantized transform coefficients are transformed and quantized to generate quantized transform coefficients, and the encoder generates image data by encoding the quantized transform coefficients. In addition, the inverse quantizer and the inverse transformer inverse quantize and inverse transform the quantized transform coefficients to reconstruct the residual block, and the adder reconstructs the current block by reconstructing the prediction block and the reconstructed residual block, and the reconstructed current block is deblocked. The deblocking filter is filtered by a deblocking filter, accumulated in units of pictures in a memory, stored as a reference picture, and used to predict the next block or the next picture.

In addition, since the second image encoder 120 encodes the prediction residual in the spatial domain, the second image encoder 120 may include all components except the transformer and the inverse transformer in the configuration of the first image encoder 120. Since the third image encoder 140 encodes the additional prediction residual in the frequency domain, the third image encoder 140 may further include a predictor for additional prediction between the subtractor, the transformer, and the quantizer in the configuration of the first image encoder 120. have. Since the fourth image encoder 150 encodes the additional prediction residual in the spatial domain, all the components of the third image encoder 140 may include all components except the transformer and the inverse transformer.

In addition, the first image encoder 120 to the fourth image encoder 140 determine whether to encode the prediction residual or the additional prediction residual in the frequency domain or the spatial domain, or whether to encode through the additional prediction. It may further comprise an adaptive controller for determining the. Such an adaptive controller may determine each case described above by determining whether a cost weighted by a Lagrange parameter and a cost due to distortion are minimized.

In FIG. 1, although the plurality of video encoders are configured as the first video encoder 120 to the fourth video encoder 150, the plurality of video encoders are merely illustrative. It may consist of more than one video encoder.

The encoding method selector 160 selects one encoding method among a plurality of encoding methods for each coding unit, and outputs image data encoded by the selected encoding method. To this end, the encoding method selector 160 analyzes the image encoding data output from each of the plurality of image encoders for each coding unit, calculates the encoding cost required for encoding according to each encoding method, and encodes the lowest encoding cost. You can choose the method. In this case, the encoding cost may be a rate-distortion cost, but various encoding costs may be used without being limited thereto.

In addition, the encoding method selector 160 accumulates and stores the selection frequency of the encoding method selected for each coding unit in the frequency memory 170. For example, when the first coding scheme is selected in the first coding unit, the encoding scheme selector 160 sets the selection frequency of the first coding scheme to 1 and stores it in the frequency memory 170. When the coding scheme is selected, the frequency of selection of the first coding scheme is increased by 1 and set to 2 and stored in the frequency memory 170. When the second coding scheme is selected as the third coding unit, the frequency of selection of the second coding scheme is selected. It is set to 1 and stored in the frequency memory 170. The encoding scheme selector 160 accumulates and stores the selection frequency of the encoding scheme selected for each coding unit in the frequency memory 170 in this manner.

In addition, the encoding scheme selector 160 may encode an encoding scheme index indicating an encoding scheme selected for each coding unit, and the number of bits of encoding scheme index data generated by encoding the encoding scheme index may be included in the encoding tool set. Can be determined by the number of schemes. That is, assuming that the number of encoding methods included in the encoding tool set is n, the number of bits of the encoding scheme index data may be log ₂ n .

The frequency memory 170 stores a selection frequency of an encoding method selected for each coding unit. The frequency of selection of the stored encoding scheme is utilized by the encoding tool set manager 110 to determine whether to update the encoding tool set.

2 is a block diagram schematically illustrating an encoding tool set manager for image encoding according to an embodiment of the present invention.

The encoding tool set manager 110 for image encoding according to an embodiment of the present invention may include a tool set update determiner 210, an additional encoding method selector 220, and a tool set update. It may be configured to include a Tool Set Updator (230) and an Update Information Encoder (240).

The tool set update determiner 210 determines whether to update the encoding tool set based on at least one of a selection frequency of the encoding scheme and an encoding cost according to the selected encoding scheme. That is, each time the tool set update determiner 210 encodes an image of a coding unit, the tool set update determiner 210 encodes according to a selection frequency of an encoding scheme stored in the frequency memory 170 and / or an encoding scheme selected by the encoding scheme selector 160. It is determined whether to update the stored encoding tool set based on the encoding cost of the generated image data.

To this end, the tool set update determiner 210 may determine to update the encoding tool set when any one of a plurality of encoding schemes is continuously selected for a predetermined number of consecutive times. That is, each time the image of the coding unit is encoded, the tool set update determiner 210 checks the selection frequency stored in the frequency memory 170 and continuously performs the preset consecutive number of encoding methods included in the encoding tool set. When the selected encoding scheme occurs, it may be determined to update the encoding tool set.

In this case, if a plurality of encoding schemes are continuously selected with a predetermined number of consecutive times regardless of the type, it may be determined to update the encoding toolset, but only when a specific encoding scheme is continuously selected among the plurality of encoding schemes. You may decide to update the encoding toolset. Here, the specific encoding scheme may be a scheme of transforming the prediction residual into a frequency domain and encoding the residual residual, as in the first encoding scheme illustrated in FIG. 3. In other words, one of a plurality of encoding schemes, in particular, a conventional encoding scheme such as the first encoding scheme is selected continuously may mean that the other encoding scheme in the encoding toolset has not been selected as the encoding scheme because it is not efficient. Therefore, in order to efficiently manage the encoding tool set, it may be decided to update the encoding tool set.

In addition, the tool set update determiner 210 may determine that the encoding tool set is updated when there is an encoding method in which the encoding cost is selected to be greater than or equal to a reference number of times. That is, the tool set update determiner 210 calculates an encoding cost according to a selected encoding method each time an image of a coding unit is encoded, checks whether the calculated encoding cost is greater than a preset cost threshold, and checks the frequency memory ( If the encoding method in which the encoding cost is greater than the preset cost threshold is selected from the plurality of encoding methods included in the encoding tool set by checking the selection frequency stored at 170, it is determined to update the encoding tool set. Can be. In other words, even if any one of a plurality of encoding schemes is selected, if the encoding cost is high, it may mean that the encoding scheme in the encoding tool set is not efficient. Therefore, updating the encoding tool set to efficiently manage the encoding tool set is necessary. It can be decided.

In this case, when an encoding method having a coding cost greater than a predetermined cost threshold is selected from the plurality of encoding methods, the encoding tool set may be updated. It may be determined that the encoding tool set is updated only when the method corresponds to the case described above. Here, the specific encoding method may be a method of encoding the prediction residual in the spatial domain or a method of encoding the additional prediction residual, like the second to third encoding methods except for the first encoding method illustrated in FIG. 3. .

The additional encoding method selector 220 encodes an image of a coding unit to be encoded after the updating of the encoding tool set is determined according to a remaining encoding scheme other than the encoding scheme included in the encoding tool set among preset available encoding schemes. Choose a coding scheme with the lowest cost. That is, when it is determined that the additional encoding scheme selector 220 updates the encoding toolset by the tool set update determiner 210, various encoding schemes available to the plurality of image encoders are preset in the image encoding apparatus. An encoding cost calculated by calculating encoding cost for encoding an image by controlling to encode an image of a coding unit to be encoded later according to each of the remaining encoding methods except a plurality of encoding methods included in the encoding tool set. This minimum coding scheme is selected as a coding scheme to be further included in the coding tool set. Here, the coding cost may be a rate-distortion cost but various other coding costs may be used.

The tool set updater 230 adds an encoding scheme having a minimum encoding cost to the encoding tool set, and removes the encoding scheme having the smallest selection frequency among the plurality of encoding schemes in the encoding tool set from the encoding tool set. Update the toolset. That is, the tool set updater 230 adds the encoding scheme selected by the additional encoding scheme selector 220 to the stored encoding tool set, analyzes the selection frequency stored in the frequency memory 170, and encodes the smallest selection frequency. Update the encoding toolset by removing the scheme from the encoding toolset. Here, the reason why the coding method having the smallest selection frequency is removed from the coding toolset is that the coding efficiency may be determined to be the lowest. However, the tool set updater 230 may update the encoding tool set by adding only an encoding scheme to the encoding tool set, or update the encoding tool set by removing only an encoding scheme having the smallest selection frequency from the encoding tool set. The updated encoding tool set is used when encoding an image of a next coding unit.

Also, the tool set updater 230 may initialize the selection frequency stored in the frequency memory 170 after updating the encoding tool set. That is, the tool set updater 230 updates the encoding tool set so that the updated encoding tool set can be maintained in an efficient state, and then initializes the selection frequency stored in the frequency memory 170 to the next encoding tool set. When encoding an image of a coding unit, a selection frequency is accumulated from the beginning, so that an optimal state for a corresponding encoding tool set can be maintained.

The update information encoder 240 encodes update information including additional information for identifying an encoding scheme added to an encoding tool set. In other words, the update information encoder 240 may identify the added encoding scheme so that the image decoding apparatus to be described later may identify the encoding scheme selected by the additional encoding scheme selector 220 and added to the updated encoding tool set. The update information including the information is encoded. Here, the additional information may be an encoding scheme index of an encoding scheme added as illustrated in, for example, FIG. 3. In addition, as a technique of encoding additional information, entropy coding techniques such as fixed length coding, variable length coding, arithmetic coding, and the like may be used. The code according to the technique may be predetermined based on a transform coefficient transformed into a frequency domain or a probability determined separately for pixels in a spatial domain.

Hereinafter, a process of determining and updating the encoding tool set by using FIG. 4 to FIG. 6 will be described as an example.

4 is an exemplary diagram illustrating a coding tool set according to an embodiment of the present invention.

For example, assuming that the encoding scheme available in the image encoding apparatus 100 is set as illustrated in, for example, FIG. 3, an initial encoding tool set stored in the encoding tool set manager 110 is illustrated in FIG. 4. As illustrated, whenever the image encoding apparatus 100 encodes an image of a coding unit, the encoding tool set manager 110 determines whether to update the encoding tool set by determining whether to update the encoding tool set. In this case, as illustrated in FIG. 4, the encoding tool set may be updated in various ways such as the first updated encoding tool set and the second updated encoding tool set.

Referring to FIG. 4, although the initial encoding tool set includes a first encoding scheme and a second encoding scheme, whenever the tool set update determiner 210 encodes an image of a coding unit, it is determined whether to update or not. If the following decision is made, the additional coding scheme selector 220 selects a third coding scheme based on the coding cost of the image of the coding unit to be coded in the future, so that the tool set updater 230 selects a frequency of selection from the initial coding toolset. A first updated encoding tool set is configured by adding a third encoding scheme selected to remove and add a second encoding scheme based on the second encoding scheme, wherein the first updated encoding tool set includes a first encoding scheme and a third encoding scheme. It can be configured. In a similar manner, a second updated encoding tool set including the first encoding scheme and the fourth encoding scheme may be configured.

5 and 6 are exemplary diagrams for describing a process of determining whether to update an encoding tool set and updating according to an embodiment of the present invention.

In FIGS. 5 and 6, when an initial encoding tool set is configured as illustrated in FIG. 4, encoding is performed by using a selection frequency of an encoding method selected each time an image of a coding unit is encoded and an encoding cost according to the selected encoding method. An example of updating the encoding tool set by determining whether to update the tool set is illustrated.

In FIGS. 5 and 6, when the image encoding apparatus 100 encodes a series of pictures, such as the first to n-th pictures, constituting a video, the pictures are encoded in units of blocks as predetermined coding units, and each picture is 16 blocks. It is assumed to consist of. However, this is merely exemplary and the coding unit may be a formal region such as a slice, a picture, a sequence, etc., or a non-standard region other than the block. In addition, each picture is composed of only 16 blocks, but each picture may be composed of various blocks, such as 32, 64, 128.

5 and 6, numerals indicated in each block represent an encoding scheme index indicating a coding scheme selected when the corresponding block is encoded. Accordingly, '1' represents the first coding scheme, '2' represents the second coding scheme, '3' represents the third coding scheme, and '4' represents the fourth coding scheme.

Referring to FIG. 5, in the process of encoding each block by using an initial encoding tool set including a first encoding scheme and a second encoding scheme, the encoding scheme selector 160 accumulates the encoding scheme selected for each block. The frequency is stored in the frequency memory 170, and the tool set update determiner 210 determines whether to update the selected frequency stored in the frequency memory 170 each time each block is encoded.

If it is assumed that the number of consecutive times is set to six times, the coding scheme in which six coding sequences are continuously selected from among the coding schemes in the encoding tool set does not occur until all blocks of the first picture are encoded. Since the first encoding scheme has been selected six times in succession in the block, the tool set update determiner 210 determines to update the initial encoding toolset before encoding the first block of the second picture.

In this case, the additional encoding scheme selector 220 may include a first encoding scheme other than the first encoding scheme and the second encoding scheme included in the initial encoding toolset among the first to fourth encoding schemes available. The encoding cost required to encode the first block of the second picture to be encoded according to each of the third encoding method and the fourth encoding method is calculated, and the encoding method having the lowest encoding cost is selected as an encoding method to be added. In FIG. 5, it is assumed that the third encoding method is selected as an encoding method to be added.

Thereafter, the tool set updater 230 updates the initial encoding tool set. First, the second encoding method having the smallest selection frequency among the encoding methods in the initial encoding tool set is removed from the initial encoding tool set, and further encoding is performed. The third encoding scheme selected by the scheme selector 220 is added to the initial encoding toolset to configure the first updated encoding toolset.

The update information encoder 240 generates update data by encoding the encoding scheme index 3 of the third encoding scheme as information for identifying the third encoding scheme selected by the additional encoding scheme selector 220. The update data generated in this way is included in the bitstream.

Subsequently, the first block of the second picture is encoded using the first updated encoding tool set including the first encoding scheme and the third encoding scheme until the encoding tool set is updated again.

Referring to FIG. 6, in the process of encoding each block by using an initial encoding tool set including a first encoding scheme and a second encoding scheme, the encoding scheme selector 160 accumulates the encoding scheme selected for each block. The frequency is stored in the frequency memory 170. The tool set update determiner 210 checks the selection frequency stored in the frequency memory 170 each time each block is encoded, and selects the encoding scheme selected when each block is encoded. The encoding cost is calculated to determine whether to update.

If the reference number is set four times, and the encoding cost for the block blocked in FIG. 6 is greater than or equal to a preset cost threshold, the encoding schemes in the encoding toolset until all blocks of the first picture are encoded. Since the coding scheme in which the coding cost is selected four times larger than the cost threshold does not occur, but the second coding scheme is selected four times in the last block of the first picture because the coding cost is larger than the cost threshold, the tool set update is determined. The flag 210 determines to update the initial encoding tool set before encoding the first block of the second picture.

In this case, the additional encoding scheme selector 220 may include a first encoding scheme other than the first encoding scheme and the second encoding scheme included in the initial encoding toolset among the first to fourth encoding schemes available. The encoding cost required to encode the first block of the second picture to be encoded according to each of the third encoding method and the fourth encoding method is calculated, and the encoding method having the lowest encoding cost is selected as an encoding method to be added. In FIG. 6, it is assumed that the fourth encoding method is selected as an encoding method to be added.

Thereafter, the tool set updater 230 updates the initial encoding tool set. First, the second encoding method having the smallest selection frequency among the encoding methods in the initial encoding tool set is removed from the initial encoding tool set, and further encoding is performed. The fourth encoding scheme selected by the scheme selector 220 is added to the initial encoding toolset to configure the first updated encoding toolset.

The update information encoder 240 generates update data by encoding the encoding scheme index 4 of the fourth encoding scheme as information for identifying the fourth encoding scheme selected by the additional encoding scheme selector 220. The update data generated in this way is included in the bitstream.

Subsequently, the first block of the second picture is encoded using the second updated encoding tool set including the first encoding method and the fourth encoding method until the encoding tool set is updated again.

7 is a flowchart illustrating a video encoding method according to an embodiment of the present invention.

According to an image encoding method according to an embodiment of the present invention, the image encoding apparatus 100 encodes an image of a coding unit according to a plurality of encoding schemes included in an encoding tool set (S710), and encodes a plurality of encoding units for each coding unit. One encoding method is selected and the image data encoded according to the selected encoding method is output (S720), the selection frequency of the encoding method selected for each coding unit is stored (S730), and the selection frequency and selection of the encoding method are selected. The encoding tool set is updated based on whether one or more encoding toolsets are updated based on one or more of encoding costs according to the encoding schemes (S740).

In operation S740, when any one of a plurality of encoding schemes is continuously selected for a predetermined number of consecutive times, the image encoding apparatus 100 updates the encoding toolset or sets a preset encoding cost among the selected encoding schemes. If there is an encoding method selected more than the reference number of times larger than the cost threshold value, the encoding tool set may be updated.

In operation S740, the image encoding apparatus 100 may determine an image of a coding unit to be encoded after the updating of the encoding tool set is determined according to a remaining encoding scheme other than the encoding scheme included in the encoding tool set among preset available encoding schemes. The encoding tool set may be updated by adding an encoding method having a minimum encoding cost to the encoding tool set.

In operation S740, the image encoding apparatus 100 may update the encoding tool set by removing the encoding method having the smallest selection frequency from among the plurality of encoding methods in the encoding tool set.

In addition, the image encoding apparatus 100 may initialize the selection frequency after updating the encoding tool set, and additional information for identifying an encoding scheme added to the updated encoding tool set every time the encoding tool set is updated. Update information including may be encoded.

The image encoding apparatus 100 may further encode an encoding scheme index indicating an encoding scheme selected for each coding unit, and the number of bits of encoding scheme index data generated by encoding the encoding scheme index is included in the encoding tool set. It may be determined by the number of coding schemes.

8 is a flowchart illustrating an example of a method of determining whether to update an encoding tool set according to an embodiment of the present invention.

When the image encoding apparatus 100 determines whether to update the encoding tool set in step S740 illustrated in FIG. 7, the image encoding apparatus 100 may determine the sequence in the order shown in FIG. 8.

That is, the image encoding apparatus 100 determines whether the first encoding scheme illustrated in FIG. 3 is continuously selected at a preset continuous number (S810), and the first encoding scheme is not continuously selected at the preset continuous number. If not, it is determined whether there is an encoding method in which the encoding cost is greater than the threshold number greater than the threshold value (S820). (S830). However, as a result of the determination in step S810, when the first encoding method is continuously selected for a predetermined number of consecutive times, or as a result of the determination in the step S820, when there is an encoding method in which the encoding cost is larger than the reference number of times, the selection frequency is greater than the threshold. The encoding tool set can be updated by removing the smallest encoding cost from the encoding tool set (S840) and adding an encoding method having the lowest encoding cost to the encoding tool set among other encoding methods other than the encoding tool set (S850). .

9 is a block diagram schematically illustrating an image decoding apparatus according to an embodiment of the present invention.

The image decoding apparatus 900 according to an embodiment of the present invention may include an encoding tool set manager 910, a frequency memory 920, and a plurality of image decoders.

The encoding tool set manager 910 decodes the encoding scheme index data and the update data extracted from the bitstream to restore the encoding scheme index and the update information, and encodes the encoding scheme index among the plurality of encoding schemes included in the encoding toolset. A coding scheme identified by the coding scheme is selected, an image of a coding unit reconstructed according to a decoding scheme corresponding to the selected coding scheme is output, and the coding tool set is updated based on the selection frequency and the reconstructed update information. In addition, the encoding tool set manager 910 accumulates and stores the occurrence frequency of the encoding scheme identified by the encoding scheme index restored for each coding unit, in the frequency memory 920. The encoding tool set manager 910 will be described in detail with reference to FIG. 10 in a later process.

The frequency memory 920 stores a frequency of selection of a coding scheme selected for each coding unit. That is, the frequency memory 920 stores the selection frequency delivered from the encoding tool set manager 910.

The plurality of image decoders reconstruct an image of a coding unit by decoding image encoded data extracted from a bitstream according to a decoding scheme corresponding to a selected encoding scheme. The plurality of image decoders may be configured with the number of encoding schemes available to the image decoding apparatus 900. For example, when the coding scheme available as described above with reference to FIG. 3 is the first to fourth coding schemes, the first video decoder 930 to the fourth video decoder 960 illustrated in FIG. 9 may be used. ) May be a decoder for decoding an image according to an image decoding scheme corresponding to the first to fourth encoding schemes, respectively.

In this case, the first image decoder 930 may include a decoder, an inverse quantizer and an inverse converter, a predictor, an adder, a deblocking filter, a memory, and the like. Here, the decoder decodes the image coded data extracted from the bitstream to restore the quantized transform coefficients, the inverse quantizer and the inverse transformer inverse quantized and inverse transform the recovered quantized transform coefficients to restore the residual block, A predictive block is generated by predicting the current block through inter prediction or intra prediction, and the adder may reconstruct the current block by adding the reconstructed residual block and the predictive block. The current block to be reconstructed is deblocked filtered by a deblocking filter, accumulated in units of pictures, and output as a reconstructed image or stored in a memory so that the predictor is used to predict the next block or the next picture.

In addition, since the second image encoder 940 decodes the image encoded data by a decoding method corresponding to an encoding method for encoding the prediction residual in the spatial domain, the second image encoder 940 removes all components of the first image encoder 930 except the inverse converter. The decoder may decode the image encoded data to restore a quantized signal. Since the third image decoder 950 decodes the image encoded data according to a decoding scheme corresponding to an encoding scheme encoded in the frequency domain with respect to the additional prediction residue, the inverse transformer and the adder in the configuration of the first image decoder 930. It may be configured to further include a predictor for further prediction in between. Since the fourth image decoder 960 encodes the additional prediction residual in the spatial domain, all the components of the third image decoder 950 may include all components except the inverse converter.

In FIG. 9, the plurality of video decoders are configured as a first video decoder 930 to a fourth video decoder 960, but this is merely an example. The decoder may be configured with more than a number of video decoders available.

10 is a block diagram schematically illustrating an encoding tool set manager for image decoding according to an embodiment of the present invention.

The encoding tool set manager 910 for image decoding may include an information decoder 1010, an encoding scheme selector 1020, and a tool set updater 1030.

The information decoder 1010 extracts and decodes encoding scheme index data and update data from the bitstream to restore the encoding scheme index and update information.

The encoding method selector 1020 selects an encoding method identified by an encoding method index reconstructed from among a plurality of encoding methods included in the encoding tool set, and reconstructs an image of a coding unit reconstructed according to a decoding method corresponding to the selected encoding method. Outputs In addition, the encoding method selector 1020 accumulates and stores the selection frequency of the encoding method selected for each coding unit in the frequency memory 920. For example, when the encoding tool set includes a first encoding scheme and a second encoding scheme as illustrated in FIG. 3, and the encoding scheme index reconstructed by the information decoder 1010 indicates the second encoding scheme, encoding is performed. The method selector 1020 selects a second encoding scheme as an encoding scheme for an image of a coding unit to be decoded, and decodes the image decoded data according to a decoding scheme corresponding to the second encoding scheme 940. ) May be used to output an image of a coding unit reconstructed by.

The encoding tool set manager 1030 updates the encoding tool set based on the selection frequency and the restored update information. To this end, the encoding tool set manager 1030 may update the encoding tool set by adding the encoding scheme identified by the additional information included in the reconstructed update information to the encoding tool set. In addition, the encoding tool set manager 1030 may update the encoding tool set by removing the encoding method having the smallest selection frequency among the plurality of encoding methods from the encoding tool set. For example, if the encoding scheme identified by the additional information included in the update information is the third encoding scheme, the third encoding scheme may be added to the encoding tool set. As a result of checking the selection frequency stored in the frequency memory 920 If the frequency of selection of the second coding scheme among the first coding scheme and the second coding scheme included in the coding tool set is the least, the second coding scheme may be removed from the coding toolset.

In addition, after updating the encoding tool set, the encoding tool set manager 1030 may initialize the selection frequency stored in the frequency memory 920. That is, when the encoding tool set is updated, the encoding tool set manager 1030 may initialize the selection frequency so that the encoding tool set may be managed in an efficient state.

In addition, when the update data is extracted from the bitstream, the encoding tool set manager 1030 may identify that the encoding tool set has been updated, and updates the encoding tool set before encoding the image of the coding unit at the time point at which the update data is extracted.

11 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

According to an image decoding method according to an embodiment of the present invention, the image decoding apparatus 900 restores encoding scheme index and update information by decoding encoding scheme index data and update data extracted from a bitstream (S1110). Selects a coding scheme identified by a coding scheme index to be restored from among a plurality of coding schemes included in the luxury toolset, decodes the video encoded data extracted from the bitstream according to a decoding scheme corresponding to the selected coding scheme, The image is reconstructed (S1120), the selection frequency of the encoding scheme selected for each coding unit is stored (S1130), and the encoding tool set is updated based on the selection frequency and the reconstructed update information (S1140).

In operation S1140, the image decoding apparatus 900 updates the encoding tool set by adding the encoding scheme identified by the additional information included in the reconstructed update information to the encoding tool set, or selects the least frequently among the plurality of encoding schemes. The encoding tool set may be updated by removing the encoding scheme from the encoding tool set.

In addition, the image decoding apparatus 900 may initialize the selection frequency after updating the encoding tool set.

As described above, according to an embodiment of the present invention, when encoding an image, an amount of calculation for selecting an efficient encoding method while selecting and encoding an efficient encoding method among various encoding methods for each predetermined coding unit In addition, the implementation complexity of the device can be reduced, as well as the amount of bits required to encode additional information for indicating the selected encoding scheme can be reduced, thereby improving compression efficiency and simplifying the implementation of the device.

In the above description, all elements constituting the embodiments of the present invention are described as being combined or operating in combination, but the present invention is not necessarily limited to the embodiments. In other words, within the scope of the present invention, all of the components may be selectively operated in combination with one or more. In addition, although all of the components may be implemented in one independent hardware, each or all of the components may be selectively combined to perform some or all functions combined in one or a plurality of hardware. It may be implemented as a computer program having a. Codes and code segments constituting the computer program may be easily inferred by those skilled in the art. Such a computer program may be stored in a computer readable storage medium and read and executed by a computer, thereby implementing embodiments of the present invention. The storage medium of the computer program may include a magnetic recording medium, an optical recording medium, a carrier wave medium, and the like.

In addition, the terms "comprise", "comprise" or "having" described above mean that the corresponding component may be inherent unless specifically stated otherwise, and thus excludes other components. It should be construed that it may further include other components instead. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. Terms used generally, such as terms defined in a dictionary, should be interpreted to coincide with the contextual meaning of the related art, and shall not be interpreted in an ideal or excessively formal sense unless explicitly defined in the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, the present invention is applied to the field of image compression processing for encoding and decoding an image, so that an amount of computation or an apparatus for selecting an efficient encoding scheme while selecting and encoding an efficient encoding scheme may be used. In addition to reducing implementation complexity, the amount of bits required to encode additional information to represent the chosen encoding scheme can be reduced, which is very useful for improving the compression efficiency and generating the effect of simplifying the implementation of the device. Invention.

1 is a block diagram schematically illustrating a video encoding apparatus according to an embodiment of the present invention;

2 is a block diagram schematically illustrating an encoding tool set manager for image encoding according to an embodiment of the present invention;

3 is an exemplary diagram showing an available coding scheme according to an embodiment of the present invention;

4 illustrates an encoding tool set according to an embodiment of the present invention.

5 and 6 are exemplary diagrams for explaining a process of determining and updating a coding tool set according to an embodiment of the present invention;

7 is a flowchart illustrating a video encoding method according to an embodiment of the present invention;

8 is a flowchart illustrating an example of a method of determining whether to update an encoding tool set according to an embodiment of the present invention;

9 is a block diagram schematically illustrating an image decoding apparatus according to an embodiment of the present invention;

10 is a block diagram schematically illustrating an encoding tool set manager for image decoding according to an embodiment of the present invention;

11 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

Claims (20)

In the apparatus for encoding a video, A plurality of image encoders encoding an image of a coding unit according to a plurality of encoding schemes included in an encoding tool set; An encoding scheme selector for selecting one encoding scheme among the plurality of encoding schemes for each coding unit and outputting image data encoded by the selected encoding scheme; A frequency memory for storing a selection frequency of an encoding scheme selected for each coding unit; And An encoding tool set manager configured to update the encoding tool set by determining whether to update the encoding tool set based on at least one of a frequency of selection of the encoding scheme and an encoding cost according to the selected encoding scheme. An image encoding apparatus comprising a. The method of claim 1, wherein the encoding tool set manager, A tool set update determiner that determines whether to update the encoding tool set based on at least one of a frequency of selection of the encoding scheme and an encoding cost according to the selected encoding scheme; Encoding that minimizes the encoding cost when encoding an image of a coding unit to be encoded after the updating of the encoding tool set is determined according to a remaining encoding scheme other than the encoding scheme included in the encoding tool set among preset available encoding schemes. An additional encoding scheme selector for selecting the scheme; The encoding tool set having the minimum encoding cost is added to the encoding tool set, and the encoding method having the least selection frequency among the plurality of encoding methods in the encoding tool set is removed from the encoding tool set. A tool set updater for updating the program; And An update information encoder for encoding update information including additional information for identifying an encoding scheme added to the encoding tool set. An image encoding apparatus comprising a. In the apparatus for decoding an image, A frequency memory for storing a selection frequency of an encoding scheme selected for each coding unit; Coding scheme index data and update data extracted from a bitstream are decoded to restore coding scheme index and update information, and a coding scheme identified by the restored coding scheme index is selected from a plurality of coding schemes included in an encoding tool set. An encoding tool set manager configured to output an image of a coding unit reconstructed according to a decoding scheme corresponding to the selected encoding scheme, and to update the encoding tool set based on the selection frequency and the restored update information; And A plurality of image decoders for reconstructing the image of the coding unit by decoding the image encoded data extracted from the bitstream according to the decoding scheme corresponding to the selected encoding scheme. Video decoding apparatus comprising a. The method of claim 3, wherein the encoding tool set manager, An information decoder for extracting and decoding the encoding scheme index data and the update data from the bitstream to restore encoding scheme index and update information; An encoding method that selects an encoding method identified by the reconstructed encoding method index among a plurality of encoding methods included in the encoding tool set, and outputs an image of a coding unit reconstructed according to a decoding method corresponding to the selected encoding method A mode selector; And An encoding tool set manager for updating the encoding tool set based on the selection frequency and the restored update information Video decoding apparatus comprising a. In the method of encoding an image, Encoding an image of a coding unit according to a plurality of encoding schemes included in an encoding tool set; Selecting one encoding method among the plurality of encoding methods for each coding unit, and outputting image data encoded according to the selected encoding method; Storing a selection frequency of an encoding scheme selected for each coding unit; And Updating the encoding tool set by determining whether to update the encoding tool set based on at least one of a frequency of selection of the encoding scheme and an encoding cost according to the selected encoding scheme. Image encoding method comprising a. The method of claim 5, wherein updating the encoding tool set, And if any one of the plurality of encoding schemes is continuously selected for a predetermined number of consecutive times, updating the encoding tool set. The method of claim 5, wherein updating the encoding tool set, And the encoding tool set is updated when there is an encoding scheme in which the encoding cost is selected to be greater than or equal to a reference number of times, among the selected encoding schemes. The method of claim 5, wherein updating the encoding tool set, Encoding that minimizes the encoding cost when encoding an image of a coding unit to be encoded after the updating of the encoding tool set is determined according to a remaining encoding scheme other than the encoding scheme included in the encoding tool set among preset available encoding schemes. And encoding the encoding tool set by adding a method to the encoding tool set. The method of claim 5, wherein updating the encoding tool set, And encoding the encoding tool set by removing the encoding method having the smallest frequency of selection among the plurality of encoding methods in the encoding tool set from the encoding tool set. The method of claim 5, wherein the video encoding method comprises: And initializing the selection frequency. The method of claim 5, wherein the video encoding method comprises: And encoding update information including additional information for identifying an encoding scheme added to the updated encoding tool set each time the encoding tool set is updated. The method of claim 5, wherein the plurality of encoding schemes, A first coding scheme for coding the prediction residuals in the frequency domain, a second coding scheme for coding the prediction residuals in the spatial domain, a third coding scheme for coding the additional prediction residues in the frequency domain, and a spatial domain for the additional prediction residues And at least one of the fourth encoding schemes to be encoded. The method of claim 5, wherein the video encoding method comprises: And encoding a coding scheme index indicating the selected coding scheme for each coding unit. The method of claim 13, And the number of bits of encoding scheme index data generated by encoding the encoding scheme index is determined by the number of encoding schemes included in the encoding tool set. In the method of decoding an image, Restoring encoding scheme index and update information by decoding encoding scheme index data and update data extracted from the bitstream; Selecting an encoding scheme identified by the reconstructed encoding scheme index among a plurality of encoding schemes included in an encoding tool set, and decoding image encoded data extracted from the bitstream according to a decoding scheme corresponding to the selected encoding scheme. Restoring an image of a coding unit; Storing a selection frequency of an encoding scheme selected for each coding unit; And Updating the encoding tool set based on the selection frequency and the restored update information. Image decoding method comprising a. The method of claim 15, wherein updating the encoding tool set, And encoding the encoding tool set by adding the encoding scheme identified by the additional information included in the restored update information to the encoding tool set. The method of claim 15, wherein updating the encoding tool set, And removing the encoding method having the least selection frequency among the plurality of encoding methods from the encoding tool set to update the encoding tool set. The method of claim 15, wherein the image decoding method, And initializing the selection frequency. The method of claim 15, wherein the plurality of encoding schemes, A first coding scheme for coding the prediction residuals in the frequency domain, a second coding scheme for coding the prediction residuals in the spatial domain, a third coding scheme for coding the additional prediction residues in the frequency domain, and a spatial domain for the additional prediction residues And at least one of the fourth encoding schemes to be encoded in the. The number of bits of the encoding scheme index data, And a method of determining the number of encoding methods included in the encoding toolset.

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