KR100734141B1 - Method and Apparatus for a Temporal ? Spatial Scalable Encoding/Decoding Based on Multiple Reference Frames - Google Patents

Abstract

The present invention relates to a method and apparatus for temporal and spatial scalable encoding and decoding referencing a plurality of frames.

According to the present invention, when encoding / decoding video information to have temporal and spatial scalability, by determining the frame to be referred to by the extended frame in units of macroblocks constituting the frame, the frame is not determined in units of frames. Each of the macroblocks constituting the same extended frame may select a reference frame individually. And, this has the effect of further improving the compression ratio than the prior art.

Description

Temporal and spatial scalable encoding and decoding method for referencing a plurality of frames, and apparatus therefor {Method and Apparatus for a Temporal & Spatial Scalable Encoding / Decoding Based on Multiple Reference Frames}

1 is a schematic diagram of a digital broadcasting system;

2 is a schematic diagram of a temporal scalable encoding / decoding method for referring to a single frame according to the prior art;

3 is a view for explaining a frame structure used in the present invention,

4 is a schematic diagram of a temporal scalable encoding / decoding method for referring to a plurality of frames according to the present invention;

FIG. 5 is a diagram illustrating a process in which one frame refers to a plurality of frames in macroblock units; FIG.

6 is a schematic diagram of a temporal and spatial scalable encoding / decoding method for referring to a plurality of frames according to the present invention;

7 is a configuration diagram of a temporal and spatial scalable encoding apparatus for referring to a plurality of frames according to the present invention;

8 is a configuration diagram of a temporal and spatial scalable decoding apparatus for referring to a plurality of frames according to the present invention;

9 is a diagram illustrating a process of transmitting frame information through a heterogeneous network.

<Description of Symbols for Main Parts of Drawings>

100, 110: digital broadcasting center 200: communication network

210: first communication network 220: second communication network

310: first terminal 320: second terminal

400: Frame 500, 510, 520, 530: Macroblock

600: encoding device 610: video information input unit

620: frame extraction unit 630: frame information generation unit

640: frame information output unit 700: decoding device

710: frame information input unit 720: frame generation unit

730: frame combination

The present invention relates to a method and apparatus for temporal and spatial scalable encoding and decoding referencing a plurality of frames. More specifically, the present invention relates to temporal and spatial scalability for digital broadcasting services such as satellite digital multimedia broadcasting (DMB). Temporal & Spatial Scalable Encoding and Decoding Method for Referencing Multiple Frames That Can Improve Compression Rate by Compressing Video Information (Data) with Spatial Scalability And device.

In general, since video information (data) has a large capacity, it is effectively compressed and transmitted or stored. As a standard of the video information (data) compression technology, moving picture MPEG (Moving Picture) of ISO / IEC (International Data Communication / International Electrotechnical Commission) Experts Group) and ITU-T (International Telecommunication Union-Telecommunication Session) H.26x series. In relation to digital broadcasting, "H.264 / MPEG4 part 10" proposed by JVT (Joint Video Team) jointly formed by "MPEG4 part2 video" or MPEG group of ISO / IEC and VCEG group of ITU-T. AVC "is mainly used.

Video compression technology takes advantage of the fact that the statistical characteristics of video data have a lot of spatial and temporal redundancy.In general, to reduce spatial redundancy, a discrete cosine transform (DCT) is performed on a frame-by-frame basis. In order to reduce temporal redundancy, differential pulse coded modulation (DPCM) is performed by searching for continuity and similarity between images from the reference image that has been encoded for each frame.

As encoding modes for video compression, there are an intra mode and an inter mode. Intra mode is a mode that converts and encodes based on continuity and similarity included in the original image itself. In addition, the inter mode is a mode for encoding based on continuity and similarity between images, which is a predictive mode for predicting a motion from an existing image in time and encoding the prediction error by comparing it with the original image. And a bi-predictive mode for predicting a motion from an image existing before or after in time and encoding the prediction error by comparing it with the original image.

1 and 2, the outline of the digital broadcasting system and the temporal scalable encoding / decoding technology according to the prior art will be described briefly. As shown in FIG. 1, the digital broadcasting center 100 includes a satellite DMB network or a terrestrial DMB network. Digital broadcasting has been performed in such a manner that the video information is transmitted using the network 200 and the DMB receiving terminals 310 and 320 receive and reproduce the same. On the other hand, although not commercially available in current digital broadcasting, there is a technology that has temporal or spatial scalability when encoding / decoding so that frame playback speed or resolution can be selected for video playback for high quality broadcasting, and among them, temporal scalability technology. This is as follows.

Referring to FIG. 2, the frames constituting the video include a plurality of basic frames B '(0), ..., B' (n-4), B '(n-2), and B for basic quality viewing. '(n), B' (n + 2), ...) and a plurality of extended frames T '(1), ..., T' ( n-3), T '(n-1), T' (n + 1), ...) and encodes the basic frame and the extended frame, respectively, to generate the basic frame information and the extended frame information. During playback, temporal scalability is achieved by decoding only basic frame information or by decoding and combining both basic frame information and extended frame information.

Looking at the processing technique for the frame for this purpose, the first frame (B '(0)) of the basic frame is processed in the intra mode from the original image, the subsequent basic frames (B' (2), ..., B ' (n-4), B '(n-2), B' (n), B '(n + 2), ...) are mainly used in inter mode by comparing continuity and similarity with previous or subsequent frames. If the continuity and similarity with the processed or neighboring frames is low (e.g., the scene is switched), it is processed in intra mode.

Meanwhile, separate extended frame information is generated for high-definition viewing with better frame playback speed than the basic frame. As shown in FIG. 2, the extended frame T '(n + 1) generally corresponds to the previous basic frame B'. (n) or later (inter mode processing) with reference to base frame B '(n + 2) or with reference to previous extended frames T' (n-3), T '(n-1) Inter mode processing). The extended frames T '(1), ..., T' (n-3), T '(n-1), T' (n + 1), and the like generated in this way are respectively the basic frames B '(0). By inserting between B '(n-4), B' (n-2) and B '(n), the frame reproduction speed is doubled.

However, the temporal or spatial scalable encoding / decoding technique according to the prior art has determined a frame to be referred to in units of frames when the extended frame is processed in inter mode (eg, forward prediction mode and bidirectional prediction mode). There was a limit.

The present invention was devised to solve the above-mentioned problems of the prior art, and an object of the present invention is to separately macro macro blocks constituting the same extended frame when compressing moving picture information (data) to have temporal and spatial scalability. The present invention provides a method and apparatus for temporal and spatial scalable encoding and decoding capable of improving a compression rate by referring to a plurality of frames.

For this purpose, a temporal and spatial scalable encoding method for referring to a plurality of frames according to the present invention includes: a) a basic frame for viewing a basic image with respect to moving image information, and a high picture quality with a higher frame reproduction speed and resolution than the basic image; Extracting an extended frame for viewing; And b) generating basic frame information by encoding the basic frame in macroblock units and generating extended frame information by encoding the extended frame in macroblock units, wherein macroblocks constituting the same extended frame are individually referred to. And generating the basic frame information and the extended frame information so that one frame refers to a plurality of frames by selecting a frame.

In addition, the temporal and spatial scalable decoding method for referring to a plurality of frames according to the present invention includes: i) basic frame information capable of reproducing a basic frame for viewing a basic image quality, an extension having a higher frame reproduction speed and a resolution than the basic image quality; Receiving frame information; Ii) generating the basic frame by decoding the basic frame information in macroblock units, and generating an extended frame by decoding the extended frame information in macroblock units, wherein macroblocks constituting the same extended frame are individually referenced frames Generating a base frame and first and second extended frames with reference to a plurality of frames by one frame; And iii) combining the basic frame and the extended frame.

On the other hand, the temporal and spatial scalable encoding apparatus for referencing a plurality of frames according to the present invention, a video input unit for inputting video information; A frame extracting unit extracting a basic frame for viewing a basic quality from the video information and an extended frame for high quality viewing having a higher frame reproduction speed and resolution than the basic quality; Basic frame information is generated by encoding the basic frame in macroblock units, and extended frame information is generated by encoding the extended frame in macroblock units, and macroblocks constituting the same extended frame individually select reference frames. A frame information generation unit generating the basic frame information and the first and second extended frame information so that one frame refers to a plurality of frames; And a frame information output unit configured to output the basic frame information and extended frame information.

In addition, the temporal and spatial scalable decoding apparatus referencing a plurality of frames according to the present invention includes basic frame information capable of reproducing a basic frame for viewing a basic quality, high-definition viewing having a higher frame reproduction speed and resolution than the basic quality. A frame information input unit configured to receive extended frame information capable of reproducing the extended frame for the frame; Decode the basic frame information in macroblock units to generate a basic frame, and decode the extended frame information in macroblock units to generate an extended frame, wherein macroblocks constituting the same extended frame individually select reference frames. A frame generator configured to generate the basic frame and the extended frame by referring to a plurality of frames by one frame; And a frame combination unit for combining the generated basic frame and the extended frame.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments. In the following description, the same or similar components are denoted by the same reference numerals as much as possible, and detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention are omitted.

Prior to the detailed description, the terms used in the present invention are simply defined, and the term "basic quality" refers to a minimum quality (or standard quality) provided for watching a video. For example, the resolution and Refers to picture quality of frame rate of QVGA (320 x 240) and 15 fps, respectively. In addition, a frame playback speed and / or a resolution higher than the basic quality is referred to as "high definition". Similarly, for satellite DMB, for example, QVGA / 30fps, VGA / 15fps, VGA / 30fps, VGA / 60fps, XGA / 30fps, XGA / 60fps. In the present invention, for convenience of description, the image quality having a higher frame reproduction speed than the basic image quality is used as the first high image quality, and the image quality higher than the basic image quality is higher than the basic image quality.

3 is a view for explaining a frame structure used in the present invention. A frame representing one screen (image) is divided into a plurality of macroblocks. In FIG. 3, four macroblocks MB_0 (500), MB_1 (510), BM_2 (520), and MB_3 (530) are one. An example of configuring the frame 500 is shown.

The main technical idea of the present invention is that video information (data) is encoded / decoded for each macroblock constituting a frame as described above, which will be described in detail below.

4 is a schematic diagram of a temporal scalable encoding / decoding method for referring to a plurality of frames used in the present invention.

The input or transmitted video information is extracted as a basic frame for viewing a basic picture for temporal scalability and a first extended frame for high quality viewing with a higher frame reproduction rate than the basic picture. These base frames form a so-called "Base Layer" and extension frames form a so-called "Enhancement Layer".

The first frame of the basic frame is generally processed in the intra mode from the original image, and subsequent frames are mainly processed in the inter mode by comparing the continuity and similarity with previous or subsequent frames, and the continuity and similarity with neighboring frames are compared. If it is low (eg when the scene is switched), it is processed in intra mode.

Although not shown in detail with reference to FIG. 4, assuming that B (0) is the first frame, B (0) is composed of four macroblocks, and each macroblock can be referred to as a frame (reference frame). Since it does not exist, it is processed in intra mode from the original image itself. On the other hand, B (n), which is the nth basic frame, is similarly composed of four macroblocks, and each macroblock has neighboring basic frames B (n-4), B (n-2), and B (n + 2). ) And continuity and similarity are compared with the macroblocks constituting the &lt; RTI ID = 0.0 &gt; etc., &Lt; / RTI &gt;

FIG. 5 illustrates a process in which one frame refers to a plurality of frames in macroblock units, and macroblocks constituting the n-th frame are compared with the macroblocks constituting the previous frame and continuity and similarity, respectively. The processing in the inter mode is shown with reference to the most similar macroblock. In FIG. 5, for example, a first macroblock of macroblocks constituting an nth frame refers to a macroblock constituting an n-2nd frame, and a second macroblock refers to a macroblock constituting an n-1th frame. For reference, the third macroblock refers to a macroblock constituting the n-4th frame, whereby macroblocks constituting the same frame (eg, the nth frame of FIG. 5) are individually selected by selecting a reference frame. Frames are encoded / decoded with reference to a plurality of frames.

To this end, in the basic frame information, frame information representing the position or order of the frame among all the basic frames, reference macroblock information representing a macroblock referred to by the macroblock during encoding / decoding, and reference macroblocks A motion vector for moving to a position and prediction error information for reconstructing the macroblock by performing motion compensation on the reference macroblock are included.

Meanwhile, a separate first extended frame is generated for viewing a first high quality image having a better frame playback speed than the basic picture quality, and the first extended frame is inserted between the basic frames to improve the frame playback speed per hour. For example, the extended frames T (n-3), T (n-1), and T (n + 1) shown in FIG. 4 are the basic frames B (n-4), B (n-2), and B (n, respectively). ) To double the frame playback speed.

The first extended frames forming the first extended layer are processed in inter mode from the base frame of the base layer or from the first extended frame of its own (first extended layer). Like the base frame, each first extended frame is also a macroblock. It consists of For example, the first extended frame T (n + 1) consists of four macroblocks, each of which refers to a macroblock constituting a neighboring basic frame B (n) or B (n + 2) or in time. In the inter mode, the macroblock constituting the first extended frame T (n-3) or T (n-1) previously located is processed in the inter mode.

6 is a schematic diagram of a temporal and spatial scalable encoding / decoding method for referring to a plurality of frames according to the present invention.

Based on the base frame and the first extended frame generated as described above, separate second extended frame information is generated for viewing a second high definition having a higher resolution than the first high quality, wherein the second extended frame is the base extended frame. The same screen (picture) as the combination of the frame and the first extended frame is provided and corresponds one-to-one to the base frame and the first extended frame. For example, the second extended frame TS (n-4), TS (n-3), TS (n-2), TS (n-1), TS (n), TS (n + 1) shown in FIG. , TS (n + 2) is B (n-4), T (n-3), B (n-2), T (n-1), B (n), T (n + 1) and B, respectively. One-to-one correspondence with (n + 2), and the resolution is twice as wide and vertical respectively.

The second extended frames forming the second extended layer are processed in an inter mode from a base frame representing the same screen (picture) or from a first extended frame or a second extended frame previously located in time. Like the one extended frame, each second extended frame is composed of macroblocks. For example, the extended frame TS (n) is composed of four macroblocks, each of which refers to a macroblock constituting a basic frame B '(n) representing the same picture (picture) or is previously located in time. Refer to a macroblock constituting the second extended frame TS (n-2) or TS (n-1) or refer to a first extended frame T (N + 1) located later in time to process in inter mode do

Similarly, in the first and second extended frame information, frame information, reference macroblock information representing a macroblock referred to by the corresponding macroblock during encoding / decoding, and reference macroblocks may be precisely positioned so that extended frames may be sequentially configured. A motion vector for moving to and a prediction error information for reconstructing the macroblock by performing motion compensation on the reference macroblock are included.

7 is a block diagram of a temporal and spatial scalable encoding apparatus for referring to a plurality of frames according to the present invention. The encoding apparatus 600 according to the present invention includes a video input unit 610 to which video information (data) is largely input, and a frame extraction unit to extract basic frames and extended frames (first and second extended frames) from the video information. 620, a frame information generation unit 630 for generating basic frame information and extended frame information by encoding the basic frame and the extended frame in macroblock units, and the basic frame information and extended frame information (first and second). Frame information output unit 640 for outputting extended frame information).

The moving picture information or moving picture data is information (data) generated by a video camera, a movie shooting device, or the like, and, in principle, refers to information that has not yet been compressed (encoded). However, even if data compressed (encoded) information is decompressed (decoded) when inputted to the video input unit 610 or information that can generate (restore) an original frame, the information is included in the video information according to the present invention. something to do.

The video information input to the video input unit 610 is transmitted to the frame extractor 620, and the frame extractor 620 uses a frame reproduction speed and / or a basic frame for viewing a basic picture from the video information. Extract extended frame for high resolution viewing. For example, the basic frame is extracted with respect to the video information at a predetermined basic period, and the first extended frame except for the basic frame is extracted at a period faster than the basic period (for example, one half of the basic period). The second extended frame having a higher resolution is extracted based on the base frame and the first extended frame.

The basic frame and the first and second extended frames are transmitted to the frame information generator 630, and the frame information generator 630 encodes them in units of macroblocks, respectively. First and second extended frame information). As described in detail above, the macroblocks constituting the same extended frame each select a reference frame individually, so that one frame is referred to a plurality of frames to generate frame information. Meanwhile, the frame information generator 630 generates a first extended frame information by encoding a basic frame in macroblock units and generating a basic frame information by encoding the first frame and a first extended frame in macroblock units. The first extended frame information generating unit and the second extended frame information generating unit for generating the second extended frame information by encoding the second extended frame in macroblock units, are respectively divided into basic frame information and the first and second It is also preferably configured to generate extended frame information. Finally, the frame information output unit 640 outputs the generated basic frame information and the first and second extended frame information to the outside.

The detailed process of generating the basic frame information and the extended frame information from the basic frame and the extended frame may refer to the above-described encoding method, and thus redundant description thereof will be omitted.

So far, a method and apparatus for encoding temporal and spatial scalable encoding referring to a plurality of frames have been described. Hereinafter, a method and apparatus for decoding basic frame information and extended frame information encoded by the above-described process will be described.

For convenience of description, a decoding method and apparatus for referring to a plurality of frames according to the present invention will be described with reference to FIG. 8.

The decoding apparatus 700 according to the present invention largely includes a frame information input unit 710, a frame generator 720, and a frame combination unit 730.

The frame information input unit 710 may include basic frame information for reproducing a basic frame for viewing a basic image from outside, and a first extension for reproducing a first extended frame for viewing a first high quality image having a higher frame reproduction speed than the basic quality. Receives or receives frame information and second extended frame information capable of reproducing a second extended frame for viewing a second high definition having a higher resolution than the first high definition. The received (input) basic frame information and the first and second extended frame information are decoded in macroblock units by the frame generator 720, respectively, and thus are encoded into the basic frame and the first and second extended frames before being encoded. Is restored. That is, during decoding, the frame is restored based on the reference macroblock information, the motion vector, and the prediction error information included in each frame information. In this case, the macroblocks constituting the same extended frame are individually separated by the reference macroblock information. By selecting a reference frame (exactly a macroblock), one frame is decoded with reference to a plurality of frames. The frame generator 720 decodes the basic frame information in macroblock units to generate a basic frame, and decodes the first extended frame information in macroblock units to generate a first extended frame. The extended frame generator is divided into a second extended frame generator for generating a second extended frame by decoding the second extended frame information in macroblock units, so as to separately generate a basic frame and a first and second extended frame. It is also preferable that it is comprised.

The generated basic frame and the first and second extended frames are combined in the frame combination unit 730 to generate original video information (data). On the other hand, when combining the basic frame and the first and second extended frame in the frame combination unit 730, it is possible to view the basic quality by outputting only the basic frames according to the type of the terminal that can play the user selection or the video or It is preferable to output both the basic frame and the first extended frame to view the first high definition, or to output the second extended frame to select the second high definition. That is, the frame combination unit 730 combines only the basic frame, or combines the basic frame and the first extended frame together, or combines only the second extended frame, based on image quality selection information input by a user. The combination of all of the first and second extended frames may be implemented to provide a user with a desired video quality.

Since the method and apparatus for temporal and spatial scalable decoding referencing the plurality of frames described above are to decode basic frame information and extended frame information generated by the method and apparatus for temporal and spatial scalable encoding referring to the plurality of frames described above, The basic principles and details thereof may refer to the contents of the encoding method and apparatus.

Meanwhile, as shown in FIG. 9, when the present invention is applied to digital broadcasting such as satellite DMB, the basic frame information and the extended frame information (first and second extended frame information) generated by the encoding apparatus are different from each other. It is also desirable to transmit to a user terminal through a communication network. For example, the basic frame information is transmitted through a first communication network specialized for digital broadcasting (eg, satellite DMB network, terrestrial DMB network, etc.) 210, and extended frame information is not a professional digital broadcasting network but is a commercially available system. By transmitting through the two communication networks (eg, wireless Internet, wired Internet, mobile communication network, etc.) 220, it is possible to reduce the load of the first communication network.

In addition, the DMB receiving terminals 310 and 320 receive only basic frame information according to its performance (function) or user selection to provide basic quality broadcasting or receive both basic frame information and extended frame information to broadcast in high quality. Can be provided.

Although the present invention has been described in detail with reference to preferred embodiments, it will be apparent to those skilled in the art that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. One embodiment is to be understood in all respects as illustrative and not restrictive. For example, in the above-described embodiment, a case in which the spatial scalability technique is applied again after the temporal scalability technique is applied as an example, on the contrary, includes the case where the temporal scalability technique is applied after the spatial scalability technique is applied. Will be included.

In addition, the scope of the present invention is specified by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts are included in the scope of the present invention. Should be interpreted as

According to the present invention, when encoding / decoding video information to have temporal and spatial scalability, the same extended frame is configured by determining the frame to be referred to by the extended frame in units of macroblocks constituting the frame, rather than determining the frame to be referred to. Each of the macroblocks has an effect of further improving the compression rate by individually selecting the reference frame.

Claims (11)

a) extracting a basic frame for basic image viewing and a first extended frame for first high definition viewing having a higher frame reproduction speed and resolution than the basic image with respect to the video information; b) generating basic frame information by encoding the basic frame in macroblock units; c) generating first extended frame information by encoding the first extended frame in units of macroblocks, wherein macroblocks constituting one first extended frame each select a reference frame so that one first extended frame is Generating first extended frame information to refer to the plurality of frames; And d) generating a second extended frame for viewing a second high definition having a higher resolution than the first high definition based on the basic frame and the first extended frame, encoding the second extended frame in units of macroblocks; Generating second extended frame information, and generating second extended frame information so that one second extended frame refers to a plurality of frames by each of the macroblocks constituting one second extended frame individually selecting a reference frame; ; Temporal and spatial scalable encoding method for referring to a plurality of frames comprising a. The method of claim 1, e) outputting the basic frame information, the first extended frame information, and the second extended frame information to different communication networks, further comprising the step of referring to a plurality of frames. The method according to claim 1 or 2, Each of the first extended frames is inserted between the respective basic frames. And the second extended frame corresponds one to one to the base frame and the first extended frame in a temporal order. The method according to claim 1 or 2, The basic frame information includes reference macroblock information, a motion vector, and prediction error information. The method according to claim 1 or 2, And each of the first and second extended frame information includes reference macroblock information, a motion vector, and prediction error information. Iii) basic frame information capable of reproducing a basic frame for viewing a basic quality, first extended frame information having a higher frame reproduction speed and resolution than the basic quality, and a second extension having a higher frame reproduction speed and resolution than the first extended frame; Receiving frame information; Ii) generating a basic frame by decoding the basic frame information in a macroblock unit, and generating an extended frame by decoding the first and second extended frame information in a macroblock unit, wherein one first and second extended frame is generated; Generating each of the base frame and the first and second extended frames by referring to a plurality of frames, wherein each of the first and second extended frames each selects a reference frame individually; And Iii) a method of temporal and spatial scalable decoding referencing a plurality of frames comprising combining said base frame, said first extended frame and said second extended frame. A video input unit to which video information is input; From the video information, a basic frame for viewing a basic quality, and a first extended frame for first high quality viewing having a higher frame reproduction speed and resolution than the basic quality are extracted, and the basic frame and the first in chronological order. A frame extracting unit which extracts a second frame for viewing a second high definition having a higher resolution than the first high definition corresponding to an extended frame one-to-one; A frame information generation unit generating basic frame information from the basic frame and generating first and second extended frame information from the first extended frame and the second extended frame; And And a frame information output unit configured to output the basic frame information and extended frame information. The frame information generation unit, A basic frame information generator for generating basic frame information by encoding the basic frame in macroblock units; The first extended frame information is generated by encoding the first extended frame in macroblock units, and macroblocks constituting the first extended frame select a reference frame individually so that one first extended frame is plural. A first extended frame information generation unit generating first extended frame information to refer to a frame of the first frame information; And The second extended frame information is generated by encoding the second extended frame in macroblock units, and macroblocks constituting the second extended frame individually select a reference frame so that one second extended frame is plural. And a second extended frame information generator configured to generate second extended frame information so as to refer to the frame of the frame. delete Basic frame information for reproducing the basic frame for viewing the basic image quality, first extended frame information for the first high definition viewing frame having a higher frame reproduction speed and resolution than the basic quality, and a frame reproduction speed and resolution higher than the first extended frame A frame information input unit configured to receive second extended frame information for high second high quality viewing; A basic frame is generated by decoding the basic frame information in macroblock units, and an extended frame is generated by decoding the first and second extended frame information in macroblock units, and constitutes one first and second extended frames. A frame generator configured to generate the base frame and the first and second extended frames with reference to a plurality of frames, wherein each of the first and second extended frames each selects a reference frame; And And a plurality of frames including a frame combination unit configured to combine the generated basic frame, the first extended frame, and the second extended frame. delete The method of claim 9, The frame combining unit combines only the basic frame, combines the basic frame and the first extended frame together, or combines only the second extended frame according to image quality selection information. Decoding device.

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