KR101867096B1 - Scalable video coding method and apparatus for enhancement layer - Google Patents

Abstract

The present invention relates to a scalable video coding method and apparatus for an enhancement layer. The encoding method is an extension block having an LCU (Largest Coding Unit) of an enhancement layer extended in size according to a difference in resolution between layers from an LCU of a base layer, Determining whether to use the mode; And signaling whether to use the determined extended block mode.

Description

[0001] SCALABLE VIDEO CODING METHOD AND APPARATUS FOR ENHANCEMENT LAYER [0002]

The present invention relates to an image processing technique, and more particularly, to a scalable video coding method and apparatus for encoding / decoding an image.

Recently, broadcasting service with HD (High Definition) resolution (1280x1024 or 1920x1080) has been expanded not only in Korea but also in the world, so that many users are accustomed to high resolution and high image quality. Therefore, many organizations are spurring on development of next generation video equipment . In addition, as interest in UHD (Ultra High Definition) with resolution more than four times that of HDTV with HDTV increased, video standardization organizations became aware of the necessity of compression technology for higher resolution, high image quality. In addition, it provides higher quality than existing video coding compression standard H.264 / AVC (Advanced Video Coding) used in HDTV, mobile phone, etc., A new standard is needed that can be Currently, Moving Picture Experts Group (MPEG) and Video Coding Experts Group (VCEG) jointly work on standardization of High Efficiency Video Coding (HEVC), the next generation video codec. The outline goal of HEVC is to encode the images including UHD images at a compression efficiency twice that of H.264 / AVC. In addition to HD and UHD images, HEVC can provide high-quality images at lower frequencies than those currently available in 3D broadcasting and mobile communication networks.

HEVC provides prediction of the current temporal image and will provide spatial prediction in the future. In addition, a prediction image can be generated using various techniques for high-resolution coding, and the difference between the original image and the prediction image can be encoded. The efficiency of image coding can be increased by such predictive coding.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a scalable video coding method and apparatus capable of improving coding / decoding efficiency.

According to an aspect of the present invention, there is provided a scalable video encoding method in which an LCU (Largest Coding Unit) of an enhancement layer is divided into a plurality of sub- Determining whether to use an extended block mode that has an extended size and is set to have the same block structure as the base layer; And signaling whether to use the determined extended block mode.

The scalable video encoding apparatus according to an embodiment of the present invention includes an enhancement layer LCU having an expanded size according to a difference in resolution between layers than an LCU of a base layer, A block mode determination unit for determining whether to use the block mode; And a signaling unit for signaling whether the determined extended block mode is used or not.

According to an embodiment of the present invention, by determining whether to use the extended block mode for the LCU of the enhancement layer from the viewpoint of Rate Distortion Optimization (RD-O), the encoding information used for scalable coding The coding efficiency can be improved and the complexity of the encoder can be reduced.

1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.
2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention.
3 is a conceptual diagram schematically showing an embodiment of a scalable video coding structure based on a multi-layer.
4 is a block diagram schematically showing a configuration of a video encoding apparatus according to an embodiment of the present invention.
5 is a flowchart illustrating a scalable video coding method according to an embodiment of the present invention.
6 is a diagram for explaining an embodiment of the extended block (LB) mode.
7 is a diagram for explaining an embodiment of a non-extended block (non-LB) mode.
8 is a flow chart illustrating an embodiment of a method for determining whether to use the extended block (LB) mode.
FIG. 9 is a diagram for explaining an example of a method for determining whether to use the extended block (LB) mode.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of the embodiments 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 disclosure rather unclear.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . In addition, the description of "including" a specific configuration in the present invention does not exclude a configuration other than the configuration, and means that additional configurations can be included in the practice of the present invention or the technical scope of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

In addition, the components shown in the embodiments of the present invention are shown independently to represent different characteristic functions, which does not mean that each component is composed of separate hardware or software constituent units. That is, each constituent unit is included in each constituent unit for convenience of explanation, and at least two constituent units of the constituent units may be combined to form one constituent unit, or one constituent unit may be divided into a plurality of constituent units to perform a function. The integrated embodiments and separate embodiments of the components are also included within the scope of the present invention, unless they depart from the essence of the present invention.

In addition, some of the components are not essential components to perform essential functions in the present invention, but may be optional components only to improve performance. The present invention can be implemented only with components essential for realizing the essence of the present invention, except for the components used for the performance improvement, and can be implemented by only including the essential components except the optional components used for performance improvement Are also included in the scope of the present invention.

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

1, the image encoding apparatus 100 includes a motion prediction unit 111, a motion compensation unit 112, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, A quantization unit 140, an entropy encoding unit 150, an inverse quantization unit 160, an inverse transformation unit 170, an adder 175, a filter unit 180, and a reference image buffer 190.

The image encoding apparatus 100 performs encoding in an intra mode or an inter mode with respect to an input image and outputs a bit stream. Intra prediction is intra prediction, and inter prediction is inter prediction. In the intra mode, the switch 115 is switched to the intra mode, and in the inter mode, the switch 115 is switched to the inter mode. The image encoding apparatus 100 generates a prediction block for an input block of the input image, and then encodes the difference between the input block and the prediction block.

In the intra mode, the intraprediction unit 120 generates a prediction block by performing spatial prediction using the pixel value of the already coded block around the current block.

In the inter mode, the motion predicting unit 111 finds a motion vector by searching an area of the reference image stored in the reference image buffer 190 that is best matched with the input block. The motion compensation unit 112 generates a prediction block by performing motion compensation using a motion vector.

The subtracter 125 generates a residual block by a difference between the input block and the generated prediction block. The transforming unit 130 performs a transform on the residual block to output a transform coefficient. The quantization unit 140 quantizes the input transform coefficient according to the quantization parameter and outputs a quantized coefficient. The entropy encoding unit 150 entropy-codes the input quantized coefficients according to a probability distribution to output a bit stream.

Since the HEVC performs inter prediction coding, i.e., inter prediction coding, the currently encoded image needs to be decoded and stored for use as a reference image. Accordingly, the quantized coefficients are inversely quantized in the inverse quantization unit 160 and inversely transformed in the inverse transformation unit 170. The inverse quantized and inverse transformed coefficients are added to the prediction block through the adder 175 and a reconstruction block is generated.

The restoration block passes through the filter unit 180 and the filter unit 180 applies at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) can do. The filter unit 180 may be referred to as an adaptive in-loop filter. The deblocking filter can remove block distortion occurring at the boundary between the blocks. The SAO may add a proper offset value to the pixel value to compensate for coding errors. The ALF may perform filtering based on a comparison between the reconstructed image and the original image, and may be performed only when high efficiency is applied. The restoration block having passed through the filter unit 180 is stored in the reference image buffer 190.

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

2, the image decoding apparatus 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, a motion compensation unit 250, (260) and a reference image buffer (270).

The video decoding apparatus 200 receives the bit stream output from the encoder and decodes the video stream into an intra mode or an inter mode, and outputs a reconstructed video, i.e., a reconstructed video. In the intra mode, the switch is switched to the intra mode, and in the inter mode, the switch is switched to the inter mode. The video decoding apparatus 200 obtains a residual block from the input bitstream, generates a prediction block, and then adds the residual block and the prediction block to generate a reconstructed block, that is, a reconstruction block.

The entropy decoding unit 210 entropy-decodes the input bitstream according to a probability distribution and outputs a quantized coefficient. The quantized coefficients are inversely quantized in the inverse quantization unit 220 and inversely transformed in the inverse transformation unit 230. As a result of inverse quantization / inverse transformation of the quantized coefficients, a residual block is generated.

In the intra mode, the intraprediction unit 240 generates a prediction block by performing spatial prediction using the pixel value of the already coded block around the current block.

In the inter mode, the motion compensation unit 250 generates a prediction block by performing motion compensation using a motion vector and a reference image stored in the reference image buffer 270.

The residual block and the prediction block are added through the adder 255, and the added block is passed through the filter unit 260. [ The filter unit 260 may apply at least one of a deblocking filter, SAO, and ALF to a restoration block or a restored picture. The filter unit 260 outputs a reconstructed image, that is, a reconstructed image. The restored image is stored in the reference image buffer 270 and can be used for inter-view prediction.

Methods for improving the prediction performance of the encoding / decoding apparatus include a method of increasing the accuracy of the interpolation image and a method of predicting the difference signal. Here, the difference signal is a signal indicating the difference between the original image and the predicted image. In the present invention, the term "difference signal" may be replaced by a "difference signal "," residual block ", or "difference block" depending on the context. Those skilled in the art may influence the idea You will be able to distinguish this within the scope of not giving.

Even if the accuracy of the interpolation image increases, the difference signal can not be generated. Therefore, it is necessary to improve the coding signal performance by improving the performance of differential signal prediction, thereby reducing the difference signal to be encoded as much as possible.

As a differential signal prediction method, a filtering method using fixed filter coefficients can be used. However, since the filtering method can not adaptively use the filter coefficient according to the image characteristic, there is a limit in the prediction performance. Therefore, it is necessary to improve the accuracy of the prediction by causing the prediction block to perform filtering according to the characteristic of each prediction block.

On the other hand, the current block to be coded is a set of spatially connected pixels in the current image to be coded. The encoding target block is a unit for encoding and decoding, and may be a square or an arbitrary shape. The neighboring reconstruction block is a block in which the current encoding target block is encoded and decoded before the current encoding target block is encoded in the current encoding target image.

The predictive image is a group of prediction blocks used for coding each block from the current block to be coded to the current block to be coded in the current encoding target image. Here, the prediction block refers to a block having a prediction signal used for coding each of the current blocks in the current image to be coded. That is, the prediction block refers to each block in the prediction image.

The neighboring blocks are the neighboring prediction blocks which are the neighboring reconstruction blocks of the current block to be encoded and the prediction blocks of the neighboring reconstruction blocks. That is, the neighboring block refers to the neighboring restoration block and the neighboring prediction block together.

The prediction block of the current block to be coded may be a prediction block generated by the motion compensation unit 112 or the intra prediction unit 120 according to the embodiment of FIG. In this case, after the prediction block filtering process for the prediction block generated by the motion compensation unit 112 or the intra prediction unit 120 is performed, the subtractor 125 performs a difference between the filtered final prediction block and the original block .

The neighboring block may be a reference image buffer 190 in the embodiment of FIG. 1 or a block stored in a separate memory. Also, the neighboring reconstruction block or the neighboring prediction block generated in the image encoding process may be used as a neighboring block.

3 is a conceptual diagram schematically showing an embodiment of a scalable video coding structure using a plurality of layers to which the present invention can be applied. In Fig. 3, a GOP (Group of Picture) represents a picture group, that is, a group of pictures.

In order to transmit video data, a transmission medium is required, and the performance of the transmission medium varies depending on various network environments. A scalable video coding method may be provided for application to these various transmission media or network environments.

The scalable video coding method is a coding method for enhancing the coding / decoding performance by eliminating inter-layer redundancy by utilizing texture information, motion information, residual signal, etc. between layers. The scalable video coding method can provide various scalabilities in terms of spatial, temporal, and image quality according to surrounding conditions such as a transmission bit rate, a transmission error rate, and a system resource.

Scalable video coding can be performed using multiple layers structure to provide a bitstream applicable to various network situations. For example, the scalable video coding structure may include a base layer that compresses and processes image data using a general image encoding method, and compresses and compresses the image data using the base layer encoding information and the general image encoding method together Lt; RTI ID = 0.0 > layer. ≪ / RTI >

Here, a layer is a set of video and bitstreams classified on the basis of space (for example, image size), time (for example, coding order, image output order), image quality, it means. The plurality of layers may also have dependencies between each other.

Referring to FIG. 3, for example, a base layer may be defined by QCIF (Quarter Common Intermediate Format), a frame rate of 15 Hz, a bit rate of 3 Mbps, a first enhancement layer may be defined as CIF Format), a frame rate of 30 Hz, and a bit rate of 0.7 Mbps, and the second enhancement layer can be defined as SD (Standard Definition), a frame rate of 60 Hz, and a bit rate of 0.19 Mbps. The format, the frame rate, the bit rate, and the like are one example, and can be determined as needed. Also, the number of layers to be used is not limited to the present embodiment, but can be otherwise determined depending on the situation.

At this time, if a CIF 0.5 Mbps bit stream is required, the bit stream may be truncated so that the bit rate is 0.5 Mbps in the first enhancement layer. The scalable video coding method can provide temporal, spatial, and image quality scalability by the method described in the embodiment of FIG.

Hereinafter, a target layer, a target image, a target slice, a target unit, a target block, a target symbol, and a target bin mean layers, images, slices, units, blocks, symbols, and bins that are currently encoded or decoded, respectively. Thus, for example, the target layer may be the layer to which the target symbol belongs. The other layer is a layer excluding the target layer, which means a layer available in the target layer. That is, another layer can be used for performing decoding in the target layer. The available layers in the target layer may be, for example, temporal, spatial, or image sub-layers.

Hereinafter, the corresponding layer, the corresponding image, the corresponding slice, the corresponding unit, the corresponding block, the corresponding symbol, and the corresponding bin are the layers corresponding to the target layer, the target image, the target slice, the target unit, Image, slice, unit, block, symbol, and bin. The corresponding video means a video of another layer existing on the same time axis as the target video. If the display order of the image in the target layer and the image in the other layer are the same, the image in the target layer and the image in the other layer exist on the same time axis. Whether images are present on the same time axis can be identified using coding parameters such as POC (picture order count). The corresponding slice means a slice existing in a position corresponding to or similar to the target slice of the target image spatially within the corresponding image. The corresponding unit means a unit existing in a position corresponding to or similarly corresponding to the target unit of the target image spatially within the corresponding image. The corresponding block means a block existing in a position corresponding to or spatially equivalent to the target block of the target image in the corresponding image.

Hereinafter, a slice representing a unit in which an image is divided is used to mean a divisional unit such as a tile, an entropy slice, and the like. Independent image encoding and decoding are possible between each divided unit.

Hereinafter, a block refers to a unit of image encoding and decoding. The coding or decoding unit during image coding and decoding refers to the divided unit when one image is divided into subdivided units and is then encoded or decoded. Therefore, a macroblock, a coding unit (CU), a prediction unit (PU) , A prediction unit, a transform unit (TU), a transform block, and the like. One block may be further subdivided into sub-blocks of smaller size.

The size of the encoding unit CU may range from an LCU (Largest Coding Unit) which is the largest unit to a Smallest Coding Unit (SCU) which is the smallest unit. The encoding units (CU) Can be expressed by depth information.

In consideration of the characteristics of scalable video coding as described above, inter-layer intra prediction, inter-layer inter prediction or inter-layer differential signal prediction can be performed to eliminate redundancy between layers.

According to an embodiment of the present invention, in order to provide an efficient coding method using inter-layer spatial scalability in coding or decoding the enhancement layer, the LCU of the enhancement layer has an inter-layer resolution An LB (Large Block) mode having an extended size may be defined according to the difference.

Hereinafter, a scalable video coding method according to an embodiment of the present invention will be described in detail with reference to FIGS. In the following, a method of coding an enhancement layer as described with reference to FIG. 3 will be described.

FIG. 4 is a block diagram illustrating a schematic configuration of an image encoding apparatus according to an embodiment of the present invention, and shows a configuration of a part of the encoding apparatus 100 shown in FIG.

Referring to FIG. 4, the encoding apparatus 100 may include a block mode determining unit 101 and a signaling unit 105.

For example, the block mode determination unit 101 or the signaling unit 105 may be located at the front end of the encoding apparatus 100 shown in FIG. 1, or may be located at the motion compensation unit 112 and the intra prediction unit 120 ). ≪ / RTI > However, the present invention is not limited to the position of the block mode determination unit 101 or the signaling unit 105, and the like.

The block mode determination unit 101 determines whether to use the extended block (LB) mode for the LCU of the enhancement layer and the signaling unit 105 determines whether the extended block (LB) mode determined by the block mode determination unit 101 And the like.

For example, in the extended block (LB) mode, the LCU of the enhancement layer may have an expanded size according to the difference between layers of the LCU of the base layer, and may be set to have the same block structure as the base layer .

On the other hand, the block mode determination unit 101 can determine whether to use the extended block (LB) mode for the LCU of the enhancement layer from the viewpoint of rate-distortion optimization (RD-O) And a rate-distortion cost calculator 102 for calculating a rate-distortion cost (RD cost).

More specifically, the block mode determining unit 101 determines the rate-distortion cost when using the extended block (LB) mode calculated using the rate-distortion cost calculator 102 and the rate- Rate-distortion cost to determine whether to use the extended block (LB) mode for the LCU of the enhancement layer.

That is, when the rate-distortion cost of the extended block (LB) mode is smaller than the rate-distortion cost when the extended block (LB) mode is not used for the LCU of the enhancement layer, It is determined to use the extended block (LB) mode, and conversely, when the rate-distortion cost of the extended block (LB) mode is larger, it may be determined that the extended block (LB) mode is not used.

The signaling unit 105 may designate a flag indicating whether or not the extended block mode is used, for example, a value of 'UseLBflag', and the value of 'UseLBflag' may be designated for each LCU of the enhancement layer .

Specific embodiments of the extended block (LB) mode and its determination method will be described in more detail below.

FIG. 5 is a flowchart illustrating a scalable video encoding method according to an embodiment of the present invention. The encoding method shown in FIG. 4 is a block diagram showing a configuration of an encoding apparatus according to an embodiment of the present invention, .

Referring to FIG. 5, the block mode determination unit 101 of the encoding apparatus 100 determines whether or not the extended block (LB) mode is used for the LCU of the enhancement layer (operation S300).

6, if the enhancement layer has a resolution twice that of the base layer and the size of the base layer LCU 450 is '32x32' , The size of the LCU 410 of the enhancement layer in the extended block (LB) mode may be set to '64x64' according to the resolution difference (i.e., twice) between the base layer and the enhancement layer.

Also, in the extended block (LB) mode, the block structure 415 of the enhancement layer may be used in the same manner as the block structure 455 of the base layer.

Accordingly, when the enhancement layer is encoded according to the extended block (LB) mode, the number of bits used for encoding information can be reduced.

For example, 'split_coding_unit_flag' indicating the cleavage of a block can be reduced by using the block structure 415 of the enhancement layer in the same manner as the block structure 455 of the base layer.

Further, 'skip_flag', 'pred_type' or 'skip_flag' signaled in units of the prediction unit (PU) as the size of the prediction unit (PU) of the enhancement layer is expanded twice as much as the size of the prediction unit 'merge_idx or the like can be reduced to a maximum of 1/4.

The non-LB mode in which the LB mode is not used will be described in detail with reference to an example shown in FIG. 7. In the non-LB mode, The size of the LCU 420 of the enhancement layer may be set to be equal to the size of the LCU 450 of the base layer irrespective of the resolution difference between layers.

In this case, in order to encode the LCU of the enhancement layer, the encoding apparatus 100 must undergo the same process as the encoding process of the LCU of the base layer.

Also, in the non-LB mode, the enhancement layer's block structure 425 is not associated with the base layer's block structure 455, The coding information should be signaled in the same manner as the base layer.

Thereafter, the signaling unit 105 signals whether the determined extended block (LB) mode is used (step S310).

For example, when the signaling unit 105 determines to use the extended block (LB) mode for the LCU 410 of the enhancement layer, the signaling unit 105 selects 'UseLBflag' as '1' for the corresponding LCU, If 'UseLBflag' is set to '0' for the corresponding LCU when determining to use the extended block (LB) mode for the LCU 420 of the enhancement layer (i.e., in the case of non- '.

According to the method of determining the LB mode according to the embodiment of the present invention, for the current LCU of the enhancement layer to decide whether to use the extended block (LB) mode, Whether or not to use the extended block (LB) mode can be determined based on whether or not the block (LB) mode is used.

For example, when the left and upper LCUs do not use the extended block mode, the block mode determination unit 101 may determine that the extended block mode is not used for the current LCU of the enhancement layer.

If at least one of the left and upper LCUs uses the extended block mode, the block mode determination unit 101 determines the rate-distortion cost for the current LCU of the enhancement layer through the rate-distortion cost calculation unit 102, The distortion cost may be calculated to determine whether to use the extended block mode.

FIG. 8 is a flowchart showing an embodiment of a method for determining whether to use the extended block (LB) mode.

Referring to FIG. 8, the block mode determination unit 101 first determines whether 'UseLBflag' of the left LCU adjacent to the current LCU of the enhancement layer is '1' (S500).

If the 'UseLBflag' of the left LCU is not '1', the block mode determining unit 101 checks whether the 'UseLBflag' of the left LCU adjacent to the left side of the current LCU of the enhancement layer is '1' If the 'UseLBflag' of the left LCU is not '1', it is determined that the extended block (LB) mode is not used (operation S520).

Referring to an example of the enhancement layer frame structure shown in FIG. 9, the use of the extended block (LB) mode may be determined in units of extended LCUs 410.

On the other hand, the use of the extended block (LB) mode for each of the left LCU 412 and the upper LCU 411 at the time of determining whether to use the extended block (LB) mode for the current LCU 413 of the enhancement layer (For example, 'UseLBflag') may have already been determined.

For example, 'UseLBflag' for the left LCU 412 or the upper LCU 411 may be used to minimize rate-distortion cost (RD cost) in the extended block (LB) mode and the non-extended block (non-LB) Mode. ≪ / RTI >

On the other hand, 'UseLBflag' of either the left LCU 412 or the upper LCU 411 may be determined based on the left LCU of the left LCU 412 and the 'UseLBflag' of the upper LCU 411 in accordance with the method described with reference to FIG. 8 .

If the 'UseLBflag' of the left LCU 412 and the 'UseLBflag' of the upper LCU 411 are all '0' (i.e., the left LCU 412 and the upper LCU 411 both use the extended block (LB) mode , The block mode determination unit 101 may determine not to use the extended block (LB) mode for the current LCU 413 of the enhancement layer .

If the 'UseLBflag' of the left LCU is '1' or the 'UseLBflag' of the upper LCU is '1', the block mode determination unit 101 determines that the current LCU 413 of the enhancement layer The rate-distortion cost is calculated (S540), and it is determined whether the extended block (LB) mode is the optimal mode (S550).

The block mode determining unit 101 determines whether the current block size of the extended block LB mode is the best mode based on the result of the rate-distortion optimization (RD-O) LB mode, and may decide to use a non-LB mode for the current LCU 413 of the enhancement layer if the extended block (LB) mode is not the optimal mode.

For example, when 'UseLBflag' of both the left LCU 412 and the upper LCU 411 is '1', or when 'UseLBflag' of any of the left LCU 412 and the upper LCU 411 is '1' , The block mode determining unit 101 may determine the mode to minimize the rate-distortion cost (RD cost) in the extended block (LB) mode and the non-extended block (non-LB) mode.

That is, the process of determining the use of the extended block (LB) mode by calculating the rate-distortion cost (RD cost) for the current LCU 413 of the enhancement layer is performed by using the left LCU 412 and the upper LCU 411, Can be performed only when 'UseLBflag' is set to '1'.

Accordingly, the complexity of the encoding apparatus 100 can be reduced to determine whether to use the extended block (LB) mode for each of the enhancement layer LCUs.

8, the 'UseLBflag' of the lower LCU is confirmed first. However, the 'UseLBflag' of the lower LCU may be checked first, or may be simultaneously checked in parallel Do.

Referring to FIGS. 4 to 9, it is assumed that the LCU of the enhancement layer in the extended block (LB) mode has an enlarged size according to the difference in resolution between layers, and has the same block structure as that of the base layer LCU For example, in the extended block (LB) mode, the LCU of the enhancement layer has the same block structure as that of the reference layer other than the base layer, and the present invention is not limited thereto. And may have an expanded size depending on the resolution difference.

Meanwhile, a method and apparatus for scalable video coding according to an embodiment of the present invention have been described with reference to a video coding method and apparatus. However, the scalable video decoding method according to an embodiment of the present invention is not limited to FIGS. 4 to 9 May be implemented by performing a series of steps according to the encoding method as described above.

More specifically, the scalable video decoding method and apparatus according to the embodiment of the present invention may use an extended block (LB) mode or a non-extended block (non-LB) mode as described with reference to FIGS. And the use of the extended block (LB) mode may be signaled from the encoding apparatus.

In the above-described embodiments, methods are described based on a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders or in a different order than the steps described above have. It will also be understood by those skilled in the art that the steps depicted in the flowchart illustrations are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention You will understand.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (11)

A scalable video coding method based on a plurality of layers,
Wherein an LCU (Largest Coding Unit) of an enhancement layer has an expanded size according to a difference in resolution between layers than an LCU of a base layer, and an extension block mode set to have the same block structure as the base layer Determining whether or not to use the data; And
And signaling whether to use the determined extended block mode. 2. The method of claim 1,
Calculating a rate-distortion cost according to whether the extended block mode is used for the LCU of the enhancement layer to determine whether to use the extended block mode. 2. The method of claim 1,
Wherein the use of the extended block mode is determined based on whether or not the left LCU and the upper LCU use the extended block mode for the LCU of the enhancement layer. 4. The method of claim 3, wherein the determining comprises:
And determining that the enhanced block mode is not to be used for the LCU of the enhancement layer if both of the left and upper LCUs do not use the enhancement block mode. 4. The method of claim 3, wherein the determining comprises:
Calculating a rate-distortion cost for the LCU of the enhancement layer to determine whether to use the enhancement block mode if at least one of the left and upper LCUs uses the enhancement block mode. 2. The method of claim 1, wherein the signaling step comprises:
Wherein a flag value indicating whether or not the extended block mode is used is specified for each LCU of the enhancement layer. A scalable video coding apparatus based on a plurality of layers,
A block mode determining unit for determining whether to use an extended block mode in which an LCU of an enhancement layer has an expanded size according to a resolution difference between layers than an LCU of a base layer and is set to have the same block structure as the base layer; And
And a signaling unit for signaling whether or not to use the determined extended block mode. 8. The apparatus of claim 7, wherein the block mode determination unit
Wherein whether to use the extended block mode is determined based on whether or not the left LCU and the upper LCU use the extended block mode for the LCU of the enhancement layer. 9. The apparatus of claim 8, wherein the block mode determination unit
And determines that the extended block mode is not used for the LCU of the enhancement layer when the left and upper LCUs do not use the extended block mode. 9. The apparatus of claim 8, wherein the block mode determination unit
Wherein, when at least one of the left and upper LCUs uses the extended block mode, a rate-distortion cost is calculated for the LCU of the enhancement layer to determine whether to use the extended block mode. 8. The apparatus of claim 7, wherein the signaling unit
And a flag value indicating whether to use the extended block mode is specified for each LCU of the enhancement layer.

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