KR20060108510A - Apparatus and method for predicting motion vector - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a motion vector prediction apparatus and method.

2. The technical problem to be solved by the invention

According to the present invention, in scalable video coding / decoding that supports temporal scalability of a multi-level structure such as MCTF or hierarchical B picture, a motion vector of a current step is predicted by using a motion vector of a neighboring step. It is an object of the present invention to provide a motion vector prediction apparatus and method for improving the coding efficiency of motion vectors and a video encoding / decoding device using the same.

3. Summary of Solution to Invention

The present invention provides a motion vector prediction apparatus in a video encoding system supporting scalable video coding, comprising: a motion estimator for generating a motion vector of a block to be encoded; And a predicted motion vector unit for generating a predicted motion vector of the block to be encoded using the motion vector of a predetermined neighboring block of the block to be encoded and a corresponding neighboring step block.

4. Important uses of the invention

The present invention is used in a video coding system.

Video, MCTF, Hierarchical B Picture, Motion Vector

Description

Apparatus and Method for Predicting Motion Vector

1 is a diagram illustrating an example of providing spatial scalability in scalable video coding (SVC);

2 is a diagram illustrating an example of providing time scalability using MCTF in SVC;

3 is a diagram illustrating an example of providing temporal scalability using hierarchical B pictures in SVC;

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

5 is a detailed configuration diagram of an embodiment of the motion vector extractor of FIG. 4;

6 is a flowchart illustrating an embodiment of a motion vector prediction process according to the present invention;

7 is a diagram illustrating an example of a motion vector when using an MCTF;

8 is a diagram illustrating an example of a motion vector when using a hierarchical B picture;

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

FIG. 10 is a detailed block diagram of an embodiment of a motion vector recovery unit of FIG. 9. FIG.

* Description of main parts of drawing *

110: spatial filtering unit 120: fragmentation unit

130: motion vector extraction unit 140: time filtering unit

150: spatial transform unit 160: quantization unit

170: entropy encoder 180: multiplexer

The present invention relates to an apparatus and method for predicting motion vectors, and more particularly, to an apparatus and method for predicting motion vector for improving coding efficiency of motion vectors in a scalable video coding / decoding system.

Since a medium for transmitting a current video has various transmission speeds and different resolutions of a terminal for each user, image data having a data rate suitable for each medium and the terminal is required. To this end, it is possible for the image data provider to provide a plurality of image data corresponding to the transmission speed of each medium and the resolution of the user, but this is limited due to the limitation of the storage space. However, if the image data is encoded by an image compression standard having scalability, the image data may be extracted and provided to the user according to the transmission speed of each medium and the resolution of the user.

Joint Video Team (JVT), a group of video experts from ISO / IEC and ITU-T, is working on standardizing Scalable Video Coding (SVC), a video compression standard that provides scalability. SVC provides scalability for space, time, and picture quality.

FIG. 1 is a diagram illustrating an example of providing spatial scalability in scalable video coding (SVC).

The base layer is coded in Quarter Common Intermediate Format (QCIF) / 15 Hz, the first enhancement layer is coded in Common Intermediate Format (CIF) / 30 Hz, and the second enhancement layer is coded in 4CIF / 60 Hz. In this way, spatial scalability is provided.

FIG. 2 is an example of providing time scalability using MCTF in SVC, and FIG. 3 is an example of providing time scalability using hierarchical B pictures in SVC.

MCTF and Hierarchical B Pictures are representative technologies that provide temporal scalability. The hierarchical B picture is an MCTF without an update process. In both cases, in FIG. 2 and FIG. 3, 60Hz is coded in step 1, 30Hz is coded in step 2, 15Hz is coded in step 3, and 7,5Hz is coded in step 4.

Motion vector coding, which is used in multi-stage techniques such as conventional MCTF and hierarchical B pictures, generates prediction values using motion vectors of neighboring blocks in the current stage, as in the conventional video compression standard. Code the difference with the predicted value.

However, this does not take advantage of the properties of the multilevel structure. In a multi-level structure, motion vectors of neighboring steps have much correlation. Here, the neighboring step means a higher or lower step having motion vector information available at the current step.

Therefore, the conventional method does not use the correlation of the motion vector of the neighboring step having much correlation with the motion vector of the current step, and thus does not provide the optimal coding efficiency.

The present invention has been proposed to solve the above-mentioned problem. In the scalable video coding / decoding that supports temporal scalability of a multi-level structure such as MCTF or hierarchical B picture, a motion vector of a neighboring step is determined. It is an object of the present invention to provide a motion vector prediction apparatus and method for improving the coding efficiency of a motion vector by predicting a motion vector at the present stage, and a video encoding / decoding device using the same.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

According to an aspect of the present invention, there is provided a video encoding apparatus that supports scalable video coding, and includes: a spatial filtering unit for extracting and outputting layers of various resolutions from an input image to provide spatial scalability; ; A fragmentation unit for receiving the hierarchical image and dividing the image into a GOP unit; A motion vector extractor configured to receive a GOP from the fragmentation unit, extract a motion vector of a block to be encoded, generate a predictive motion vector, and calculate a motion vector difference value that is a difference between the motion vector and the predicted motion vector; A time filtering unit for receiving the GOP image and separating the high frequency and low frequency frames to reduce temporal redundancy; A spatial transform unit for receiving a transformed frame separated from the temporal filtering unit and outputting a transform coefficient from which spatial redundancy is removed; A quantizer for receiving and transforming the transform coefficients, and an encoder for receiving and encoding the quantized transform coefficients and the motion vector difference value, wherein the motion vector extracting unit comprises: a neighboring step corresponding to a block to be encoded; A predictive motion vector of a block to be encoded is generated by using a motion vector of.

The present invention also provides a motion vector prediction apparatus in a video encoding system supporting scalable video coding, comprising: a motion estimation unit for generating a motion vector of a block to be encoded; And a predicted motion vector unit for generating a predicted motion vector of the block to be encoded, using the motion vector of a predetermined neighboring block of the block to be encoded and a corresponding neighboring step block.

In addition, the present invention provides a motion vector prediction method in a video system supporting scalable video coding or decoding, comprising: a peripheral block motion vector extraction step of extracting motion vectors of a neighboring block of a current step of a block to predict a motion vector; A neighboring step motion vector extracting step of extracting a motion vector of a neighboring step block corresponding to the block to be predicted; And a prediction motion vector generation step of calculating a prediction motion vector of the block to be predicted using the motion vector of the neighboring block and the motion vector of the neighboring step block.

In addition, the present invention provides a video decoding apparatus that supports scalable video decoding, comprising: a demultiplexer for receiving a bitstream and demultiplexing and outputting the bitstream by resolution; An entropy decoder configured to receive bitstreams of each resolution and entropy decode to extract texture information and motion vector difference values; An inverse quantization unit for inversely quantizing the texture information and outputting a transform coefficient; An inverse spatial transform unit inversely transforming the transform coefficients into transform coefficients in a spatial domain by performing spatial transform inversely; The motion vector decompressor receives the motion vector difference value, calculates a predicted motion vector of the block to be decoded, and restores the motion vector of the block to be decoded. And a reconstructed inverse time filtering unit, wherein the motion vector reconstruction unit generates a predictive motion vector of a block to be decoded by using a motion vector of a neighboring step corresponding to the block to be decoded.

In addition, the present invention is a motion vector prediction apparatus in a video decoding system that supports scalable video decoding, the block to be decoded by using the motion vector of a predetermined neighboring block of the block to be decoded and the neighboring step block corresponding thereto. And a motion vector adder for generating a predicted motion vector, and a motion vector adder for reconstructing the motion vector by adding the predicted motion vector and the motion vector difference value.

The following merely illustrates the principles of the invention. Therefore, those skilled in the art, although not explicitly described or illustrated herein, can embody the principles of the present invention and invent various devices that fall within the spirit and scope of the present invention. Furthermore, all conditional terms and embodiments listed herein are in principle clearly intended for the purpose of understanding the concept of the invention and are not to be limited to the specifically listed embodiments and states. Should be. In addition, it is to be understood that all detailed descriptions, including the principles, aspects, and embodiments of the present invention, as well as listing specific embodiments, are intended to include structural and functional equivalents of these matters. In addition, these equivalents should be understood to include not only equivalents now known, but also equivalents to be developed in the future, that is, all devices invented to perform the same function regardless of structure.

Accordingly, the functionality of the various elements shown in the figures, including functional blocks represented by a processor or similar concept, can be provided by the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functionality may be provided by a single dedicated processor, by a single shared processor or by a plurality of individual processors, some of which may be shared. In addition, the use of terms presented in terms of processor, control, or similar concept should not be interpreted exclusively as a citation of hardware capable of executing software, and without limitation, ROM for storing digital signal processor (DSP) hardware, software, and the like. (ROM), RAM, and non-volatile memory are to be understood to implicitly include. Other hardware for the governor may also be included.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. In describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

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

As shown in FIG. 4, the video encoding apparatus according to the present invention includes a spatial filtering unit 110, a fragmentation unit 120, a motion vector extractor 130, a temporal filtering unit 140, and a spatial transform unit 150. , The quantization unit 160, the entropy encoding unit 170, and the multiplexing unit 180 are configured.

The input image is divided into hierarchical images having various resolutions by the spatial filtering unit 110, and outputted to the hierarchical fragmentation unit 120, and the hierarchical images of each resolution have the same processing.

The fragmentation unit 120 classifies and outputs an image received from the spatial filtering unit 110 into a group of pictures (GOP) which is a basic unit of encoding.

The motion vector extractor 130 receives an image separated by a GOP, extracts a motion vector to be used for temporal filtering, generates a motion vector difference value, and outputs the motion vector difference to the entropy encoder 170.

5 is a detailed block diagram of an embodiment of a motion vector extractor according to the present invention.

As shown in FIG. 5, the motion vector extractor 130 includes a motion estimator 131, a predictive motion vector generator 132, and a motion vector difference unit 133.

The motion estimator 131 generates a motion vector and outputs the motion vector to the predicted motion vector generator 132 and the temporal filter 140.

The predictive motion vector generator 132 generates a predicted motion vector and outputs the predicted motion vector to the motion vector differential unit 133, and the motion vector differential unit 133 generates the motion vector and the predictive motion vector generated from the motion estimation unit 131. The motion vector difference value, which is the difference value of the predicted motion vector generated from the unit 132, is output to the entropy encoder 170.

Hereinafter, a detailed operation of the motion vector extractor 130 will be described with reference to FIG. 6.

6 is a flowchart illustrating a motion vector prediction process according to the present invention.

First, the motion estimator 131 extracts a motion vector of a block to be encoded in the current step (610).

Next, the prediction motion vector generator 132 extracts motion vectors cMV1, cMV2,..., CMVn of the neighboring block of the current step of the block to be encoded (620).

Next, a block of a neighboring step corresponding to the block to be encoded is searched (630). The neighboring step may be larger or smaller than the frame rate of the current step depending on the time filtering method. However, in the time filtering method used, the motion vectors of the neighboring steps corresponding to the current step must be known before the motion vectors of the current step. 7 is a diagram illustrating an example of a motion vector when using an MCTF. As shown in FIG. 7, in the case of the MCTF, the motion vector information may be known in the order of 3 steps, 2 steps, and 1 step. Therefore, in the case of the MCTF, the neighboring step of the first step becomes the second step.

Subsequently, the motion vectors uMV1, uMv2,..., UMVm of the corresponding block of the neighboring step are extracted (640), filtered (660), and a predicted motion vector is generated (660). The processes 640 to 660 will be described in more detail with reference to FIG. 7 as follows. In the example of FIG. 7, the motion vectors of the first stage corresponding to the motion vectors of the two stages MV ^F _{2 , 1} are MV ^F _{1 , 0} and MV ^B _{1 , 0} . The filtering process is applied to the two vectors to match the same frame rate as the vector of the current stage, and the sign is changed as necessary. In the example of FIG. 7, the two vectors are changed to 2 × MV ^F _1,0 and −2 × MV ^B _{1 , 0} . A prediction motion vector (pMV) is obtained by using Equation 1 below using the motion vector of the neighboring block of the block to be encoded in the current step and the above two vectors.

Subsequently, the motion vector difference unit 133 generates difference values (MV-pMV) between the motion vector of the block to be encoded and the predicted motion vector, and outputs the difference values to the entropy coder 160 to perform entropy encoding (670).

8 illustrates motion vector information when hierarchical B picturs are used. In the case of hierarchical B pictures, like the MCTF, the motion vector information can be known in the order of 3 steps, 2 steps, and 1 step. Therefore, the same process as the above-described MCTF example is applied to the process of obtaining pMV.

Referring to FIG. 4, the remaining components of the video encoding apparatus will be described below.

The temporal filtering unit 140 separates and codes the images of the GOP into high frequency and low frequency frames to reduce temporal redundancy. Temporal filtering methods include MCTF and Hierarchical B Pictures.

The spatial transform unit 150 removes spatial redundancy for each frame by using a discrete cosine transform or a wavelet transform. In addition, by obtaining texture information of the lower layer, spatial redundancy of each layer is also removed. The coefficients obtained by the spatial transform result are called transform coefficients.

The quantization unit 160 receives the transform coefficients from the spatial transform unit 150 and quantizes them and outputs them to the entropy encoder 170.

The entropy encoder 170 losslessly encodes the quantized transform coefficients and the motion vector difference value and outputs them as a bit stream.

The multiplexer 180 multiplexes the bitstreams of each resolution layer to provide scalability.

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

As shown in FIG. 9, the video decoding apparatus according to the present invention is a video decoding apparatus that supports scalable video decoding, including a demultiplexer 210, an entropy decoder 220, a motion vector reconstruction unit 230, The inverse quantization unit 240, the inverse spatial transform unit 250, and the inverse time filtering unit 260 are configured, and the other components except the demultiplexer 210 are installed in layers and operate in the same manner. .

The demultiplexer 210 demultiplexes the input bitstream into a bitstream for each layer providing various spatial resolutions and outputs the bitstream to the entropy encoder 220 for each layer.

The entropy decoder 220 extracts the texture information and the motion vector difference value by decoding the input bitstream and outputs the texture information and the motion vector difference.

The inverse quantizer 240 inversely quantizes the extracted texture information and outputs a transform coefficient.

The inverse spatial transform unit 250 performs a spatial transform inversely, and inversely transforms the transform coefficients into transform coefficients in the spatial domain.

The motion vector reconstruction unit 230 generates motion vectors to be used in the inverse time filtering unit by using the motion vector difference value received from the entropy decoding unit 220.

The inverse time filtering unit 260 receives the motion vector from the motion vector reconstruction unit 230, and provides an output image by performing inverse time filtering on the transform coefficient in the spatial domain, that is, the temporal difference image using the motion vector. do.

10 is a detailed configuration diagram of an embodiment of a motion vector recovery unit according to the present invention.

As shown in FIG. 10, the motion vector reconstructor 230 includes a predicted motion vector generator 231 and a motion vector adder 232.

The operation of the prediction motion vector generator 231 is the same as the operation of the prediction motion vector generator 132 of FIG. 5. The motion vector adder 232 reconstructs the motion vector by adding the motion vector differential value received from the entropy decoder 220 and the predicted motion vector value generated by the predicted motion vector generator 132.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

The present invention is applied to a video coding system having a multi-level structure such as an MCTF or a hierarchical B picture, and can increase the coding efficiency of the motion vector by predicting the motion vector of the current step using the motion vector of the neighboring step. It has an effect.

Claims (14)

A video encoding apparatus supporting scalable video coding, A spatial filtering unit for extracting and outputting images of layers having various resolutions from the input image to provide spatial scalability; A fragmentation unit for receiving the hierarchical image and dividing the image into a GOP unit; A motion vector extractor configured to receive a GOP from the fragmentation unit, extract a motion vector of a block to be encoded, generate a predictive motion vector, and calculate a motion vector difference value that is a difference between the motion vector and the predicted motion vector; A time filtering unit for receiving the GOP image and separating the high frequency and low frequency frames to reduce temporal redundancy; A spatial transform unit for receiving a transformed frame separated from the temporal filtering unit and outputting a transform coefficient from which spatial redundancy is removed; A quantizer for receiving the transform coefficients and quantizing the transform coefficients; Encoder for receiving the encoded quantized transform coefficients and the motion vector difference value, encoded and output Including but not limited to: The motion vector extractor, And a predictive motion vector of a block to be encoded is generated using a motion vector of a neighboring step corresponding to the block to be encoded. The method of claim 1, The motion vector extractor, A motion estimation unit for generating a motion vector of a block to be encoded; A predicted motion vector unit for generating a predicted motion vector of the block to be encoded using the motion vector of a predetermined neighboring block of the block to be encoded and a corresponding neighboring step block; A motion vector difference unit for calculating a difference value between the motion vector and the predicted motion vector Video encoding apparatus comprising a. The method of claim 2, The prediction motion vector unit, And a motion vector of the neighboring step is filtered and used to coincide with a frame rate of the motion vector of the current step. The method of claim 2, The prediction motion vector unit, A video encoding apparatus, characterized by generating a predicted motion vector using the following equation. [Equation]

Where pMV is a predictive motion vector, cMV1, cMV2, ..., cMVn are motion vectors of neighboring blocks of the current stage of the block to be encoded, and MV ^F _{1 , 0} and MV ^B _{1 , 0} are Motion vector of the block of the corresponding neighboring step)  A motion vector prediction apparatus in a video encoding system that supports scalable video coding, A motion estimation unit for generating a motion vector of a block to be encoded; And A predicted motion vector unit for generating a predicted motion vector of the block to be encoded using the motion vector of a predetermined neighboring block of the block to be encoded and a corresponding neighboring step block. Motion vector prediction device comprising a. The method of claim 5, The prediction motion vector unit, And filtering the motion vector of the neighboring step to match the frame rate of the motion vector of the current step. The method of claim 5, The prediction motion vector unit, Motion vector prediction apparatus, characterized in that for generating a predictive motion vector using the following equation. [Equation]

Where pMV is a predictive motion vector, cMV1, cMV2, ..., cMVn are motion vectors of neighboring blocks of the current stage of the block to be encoded, and MV ^F _{1 , 0} and MV ^B _{1 , 0} are Motion vector of the corresponding block) A motion vector prediction method in a video system supporting scalable video coding or decoding, A neighboring block motion vector extraction step of extracting motion vectors of a neighboring block of a current step of a block to predict a motion vector; A neighboring step motion vector extracting step of extracting a motion vector of a neighboring step block corresponding to the block to be predicted; And A prediction motion vector generation step of calculating a prediction motion vector of the block to be predicted using the motion vector of the neighboring block and the motion vector of the neighboring step block. Motion vector prediction method comprising a. The method of claim 8, Filtering the motion vector of the extracted neighboring step block to match the frame rate of the motion vector of the current step; Motion vector prediction method further comprising. The method of claim 8, The predictive motion vector generation step, A motion vector prediction method comprising generating a predictive motion vector using the following equation. [Equation]

(Where pMV is a predictive motion vector, cMV1, cMV2, ..., cMVn are motion vectors of blocks around the current step of the block to be predicted, and MV ^F _{1 , 0} and MV ^B _{1 , 0} are motion vectors of neighboring step corresponding blocks) A video decoding apparatus supporting scalable video decoding, A demultiplexer for receiving a bitstream and demultiplexing the output by resolution; An entropy decoder configured to receive bitstreams of each resolution and entropy decode to extract texture information and motion vector difference values; An inverse quantization unit for inversely quantizing the texture information and outputting a transform coefficient; An inverse spatial transform unit inversely transforming the transform coefficients into transform coefficients in a spatial domain by performing spatial transform inversely; A motion vector reconstruction unit for receiving the motion vector difference value, calculating a predicted motion vector of a block to be decoded, and reconstructing the motion vector of the block to be decoded; An inverse time filtering unit reconstructing an image by inversely time filtering the transform coefficients using the motion vector Including but not limited to: The motion vector reconstruction unit, And a predictive motion vector of a block to be decoded using a motion vector of a neighboring step corresponding to the block to be decoded. The method of claim 11, The motion vector reconstruction unit, A predicted motion vector generator for generating a predicted motion vector of the block to be decoded using the motion vector of a predetermined neighboring block of the block to be decoded and a neighboring step block corresponding thereto; A motion vector adder for reconstructing the motion vector by adding the predicted motion vector and the motion vector difference value. Video decoding apparatus comprising a. The method of claim 12, The prediction motion vector generator, A video decoding apparatus, characterized by generating a predicted motion vector using the following equation. [Equation]

Where pMV is the predictive motion vector, cMV1, cMV2, ..., cMVn is the motion vector of the neighboring block of the current stage of the block to be decoded, and MV ^F _{1 , 0} and MV ^B _{1 , 0} are Motion vector of the block of the corresponding neighboring step)  A motion vector prediction apparatus in a video decoding system supporting scalable video decoding, A predictive motion vector generator for generating a predictive motion vector of the block to be decoded by using a motion vector of a predetermined neighboring block of the block to be decoded and a neighboring step block corresponding thereto; A motion vector adder for reconstructing the motion vector by adding the predicted motion vector and the motion vector difference value. Motion vector prediction apparatus in a video decoding system comprising a.

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