KR100914318B1 - Method for forming IDR unit for trick play, and Trick play system and method using that - Google Patents

Abstract

The present invention relates to a method for generating an IDR unit for trick play, a trick play system using the same, and a method thereof, by generating an IDR unit for implementing trick play by adjusting the number and data amount of video frames in the trick play system. An IDR unit generation method for trick play, a trick play system using the same, and a method for preserving a content transmission rate and minimizing a load on a server to adjust a double speed are provided.

To this end, the present invention, in the trick play system, determining transmission conditions in IDR (Instantaneous Decoding Refresh) unit on the basis of the double speed information input means for receiving double speed information, the double speed information input through the double speed information input means; The transmission condition determining means for generating the IDR unit by adjusting the number and data amount of video frames to be transmitted, and the IDR unit generated by the IDR unit generating means by the transmission condition determining means. And transmitting means for transmitting to an external user terminal according to the determined transmission condition.

 H.264, VoD, Trick Play, Transmission Condition Determination, Video Frame Count Control, Data Volume Control, IDR Unit Generation, Double Speed Control

Description

Method for forming IDR unit for trick play, trick play system and method using same {Method for forming IDR unit for trick play, and Trick play system and method using that}

The present invention relates to a method of generating an Instantaneous Decoding Refresh (IDR) unit for trick play, a trick play system using the same, and a method thereof. More specifically, the number and data amount of a video frame in a trick play system can be determined. By generating an IDR unit to adjust the trick play by creating an IDR unit, the method of generating an IDR unit for trick play, to control the speed of the transmission to preserve the transmission rate of the original content and minimize the load on the server, a trick play system using the same and the method It is about.

First, in the present invention, "IDR unit" refers to a unit of a frame that performs 'transmission' or 'skip' at a time during a trick play, and includes an IDR frame and its dependent frames. It is generated based on double speed.

The present invention is derived from the research conducted as part of the IT new growth engine core technology development project of the Ministry of Information and Communication [Task management number: 2005-S-405-02, Title: Development of next-generation Internet server technology].

In the video on demand (VoD) system, it is very important for the user to support trick play, which corresponds to the function of the video cassette recorder (VCR) such as fast forward.

Such VoD How to implement trick play in the system is to target content such as Moving Picture Experts Group-4 (MPEG-4) or H.263. Many methods have been developed such as selection method and trick play-only content generation method.

The conventional trick play method can be largely described in two directions.

The first method is to implement a double speed by periodically removing frames from the original content. This method can efficiently adjust the speed without putting a heavy load on the server, but it does not maintain the data rate because it selects the frame regularly and does not consider the size of the compressed frame.

In this case, if the data rate is changed, an incorrect data rate may be notified to the UE at an initial setting stage with the UE through a control protocol such as RTSP (Real-Time Streaming Protocol) at the start of streaming, which may cause a hardware terminal to cause an abnormality in the buffer. Therefore, there is a problem that it is difficult to accurately stream.

The second method to solve the above problem is to re-encode and transmit the original content itself for trick play or to perform a simple encoding operation for the server to adjust the bit rate of the content in real time. to be. Although this method can compensate for the problem of the first method, there is a problem that the real time is poor and even if a simple encoding operation is put, a large load is placed on the server when a plurality of terminals are connected. In addition, since H. 264 has a higher complexity of the algorithm itself than the existing video compression standard, there is a problem that the load on the server is further increased.

Therefore, there is an urgent need for a method that can deliver high-speed effects in the H.264 system by transmitting accurate content while maintaining the transmission rate of the original content without putting a load on the server.

The present invention has been proposed to solve the above problems and to meet the needs, and by generating the IDR unit to implement the trick play by adjusting the number of video frames and the amount of data in the trick play system, to preserve the transmission rate of the original content and the server It is an object of the present invention to provide a method of generating an IDR unit for trick play, a trick play system using the same, and a method for controlling the speed by minimizing the load of the controller.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned above 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.

The system of the present invention for achieving the above object is, in a trick play system, an IDR (Instantaneous Decoding Refresh) unit based on double speed information input means for receiving double speed information and double speed information input through the double speed information input means. Transmission condition determining means for determining a transmission condition of an IDR, IDR unit generating means for generating an IDR unit by adjusting the number and data amount of video frames to be transmitted, and an IDR unit generated by the IDR unit generating means. And transmission means for transmitting to an external user terminal according to the transmission condition determined by the transmission condition determining means.

On the other hand, in the method of the present invention for achieving the above object, in the trick play method, the transmission speed information input step of receiving the double speed information, the transmission condition in IDR (Instantaneous Decoding Refresh) unit is determined based on the received double speed information A transmission condition determined in the transmission condition determining step, the IDR unit generating step of generating an IDR unit by adjusting the number of video frames to be transmitted and the amount of data to be transmitted, and the IDR unit generated in the IDR unit generating step And transmitting to the user terminal.

Meanwhile, another method of the present invention for achieving the above object is a method of generating an Instantaneous Decoding Refresh (IDR) unit for trick play, wherein the entire frame from the first IDR frame to the next second IDR frame A first frame removing step of removing half of the second dependent frame among the first frames; and checking whether the data size of the remaining remaining frames removed from the entire frames is less than half the data size of the entire frames to generate the corresponding frames in IDR units. And generating an IDR unit.

In addition, the other method of the present invention, the second frame removing step of proceeding to the IDR unit generation step after removing the frame referring to the removed second dependent frame in the remaining remaining frame removed in the first frame removing step It further includes.

The present invention as described above has the effect of providing a trick play service in real time by maintaining the transmission characteristics of the original content without placing a large computational load on the server.

In addition, since the present invention does not need to use a special encoding scheme or the user terminal is modified for trick play in implementing trick play, there is an effect that the service can be provided without modification of the existing content and the user terminal.

The above objects, features, and advantages will become more apparent from the detailed description given hereinafter with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains may share the technical idea of the present invention. It will be easy to implement. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist 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.

1 is a diagram illustrating an embodiment of an IDR frame and a dependent frame used in the present invention.

In general, a video consists of a series of IDR frames and dependent frames, as shown in FIG. An IDR frame is referred to as a frame referred to in H. 264, that is, a 'Reference Frame', and a dependent frame (P frame and B frame) is called a 'Prediction Frame'.

For example, suppose you have a video showing 29.97 frames per second, which means that it displays 29.97 frames per second, one picture per frame at 1000 ms / 29.97 hours. Here, H.264 video means that each frame (every picture) is compressed by H.264 compression.

In compressing a frame, H.264 compresses the frame efficiently by determining the continuity of the frame or the similarity between the frames. For example, if the IDR frame 101 and the P frame 102 are very similar, the P frame 102 extracts only the changed portion of the IDR frame 101 and compresses them separately. In this case, the compression efficiency is higher than that of simply compressing the P frame 102. At this time, since the P frame and the B frame refer to the IDR frame, if the IDR frame does not exist, the P frame and the B frame cannot be recovered (that is, the frame is regenerated by decompressing the video compressed by the H.264 method). Can not).

2 is a diagram illustrating an embodiment of a trick play system using an IDR frame according to the present invention.

As shown in FIG. 2, the trick play system using the IDR frame according to the present invention includes a speed information input unit 21 and a speed information input unit 21 for receiving a user's desired speed value S. A transmission condition determining unit 22 for determining 'transmission' or 'skipping' in IDR units (transmission condition determination) based on the double speed value S, and adjusting the number and data amount of video frames to be transmitted. The IDR unit generation unit 23 and the IDR unit generation unit 23 generating the IDR unit at the double speed are transmitted to the user terminal according to the transmission condition determined by the transmission condition determination unit 22. It includes a transmission unit 24 for the. At this time, the transmission unit 24 transmits the IDR unit to the user terminal in a known streaming (Streaming) method.

Here, the transmission condition determining unit 22 determines the 'transfer' or 'skip' in IDR units according to the result of subtracting 1 after dividing the double speed value S input to the double speed information input unit 21 by two. That is, if the result of subtracting 1 after dividing 1 by the double speed value S inputted to the double speed information input unit 21 by 2 and subtracting 1 is '0', the transmission condition determiner 22 determines 'send by IDR unit', If not, it is determined as 'skip to the next IDR frame position', and the value 1 is subtracted until the result of subtracting 1 equals to '0' after dividing the speed value (S) input to the speed information input unit 21 by 2 and subtracting 1. Repeat the above process.

In this case, the transmission condition determiner 22 divides the double speed value S by 2 and subtracts 1 from the video so that the IDR unit generator 23 processes the video frame to generate the double speed when generating the IDR unit. This is because the transmission condition determination unit 22 does not need to process the double speed because the frame is generated to generate the IDR unit.

The IDR unit generation unit 23 receives the IDR frame start position from the IDR frame start position to the subordinate frame before the next IDR frame start position, and removes the second dependent frames among the subordinate frames between the two IDR frames, and subordinates the IDR frames. An IDR unit is generated by adjusting the sum of the data sizes of the dependent frames in the first half of the frames not more than half.

Then, the process of trick-playing a frame based on the IDR frame and the dependent frame used in the present invention of FIG. 1 (see FIG. 3) and an IDR unit generation method (see FIG. 4) according to the present invention will be described in more detail. Shall be.

FIG. 3 is an exemplary explanatory diagram illustrating a process of trick-playing an IDR frame and a dependent frame, and illustrates a process of trick-playing an IDR unit generated based on a double speed. In this case, it is assumed that one unit of a frame that performs 'transmit' or 'skip' at one time is called an IDR unit, and the IDR unit is composed of an IDR frame and dependent frames.

Here, when the user wants a double speed screen, the speed value input by the trick play system is 2. Then, the trick play system (particularly, the transmission condition determiner 22) divides the double speed value 2 by 2 and divides the double speed value 2 by 2, that is, the result of subtracting 1 from 1 becomes 0. All IDR units are determined to be 'transmit', and as shown in FIG. 3, 'transmission' is continuously performed in IDR units.

On the other hand, if the user wants a screen of 4x speed, the speed value input by the trick play system is 4. Then, the trick play system (particularly, the transmission condition determiner 22) divides the double speed value, 4 by 2, and divides the double speed value 4 by 2, that is, the result of subtracting 1 from 2 becomes 1. In addition, it is determined to repeatedly perform the 'transfer' and the 'skip' of the IDR unit, and repeat the 'transmit' and 'skip' in the IDR unit as shown in FIG. 3.

Here, assuming that IDR frames exist every 30 frames and perform trick play at twice the speed, conventionally, trick play was performed at twice the speed by alternately performing 'transfer' and 'skip', but the present invention is continuous. Performs trick play at twice the speed through 15 transfers and 15 consecutive skips.

The reason is that the human eye does not notice much of the 30 ms picture change (for 30 frames of content per second), so that 15 out of 30 pieces are skipped and 15 pieces are skipped. Of course, if there is one IDR frame every 10 seconds, the user can recognize the unnaturalness of trick play, but as the current DMB (Digital Multimedia Broadcasting) standard shows, one or more IDR frames exist within one second. It does not recognize unnaturalness greatly. However, in some cases, when IDRs are present at relatively large intervals, when the speed control is set to IDR units, unnaturalness may appear, the present invention minimizes such unnaturalness by generating IDR units.

Video compression (also known as lossy compression), on the other hand, is not 100% reconstructed because it compresses while removing invisible parts (of course, it appears to be 100% reconstructed by the human eye). Thus, if you extract only the differences (changes) and compress them (removing what is invisible to the human eye, but removing something that is not perfect and slightly visible), the amount of loss gradually accumulates and the error increases.

In order to minimize such an error, a method of periodically inserting a reference frame is generally used. That is, the first chapter is used as a reference, the next 10 are compressed only with differences, and the next chapter is used as a reference frame again. For example, this process is repeated every 15 sheets in Moving Picture Experts Group-2 (MPEG-2), and is repeated every 30 sheets in MPEG-4.

If a file is played at twice the speed, playing the file one by one may be the most effective method of double speed playback. However, when double-speed playback is skipped one by one, if the IDR frame is removed, the P frame and the B frame compressed with reference to the IDR frame cannot be recovered. For example, if a central IDR frame is removed from a video composed of 'IDR, P, P, B, B, IDR, P, B, B, B, IDR', the IDR frame between the removed IDR frame and the next IDR frame P, B, B, and B become useless compressed frames, and playback is impossible.

However, playing in IDR unit may solve the problem of removing the IDR frame. For example, suppose a video plays (IDR, P, B, B), (IDR, P, B, B), (IDR, P, B, B) at twice the speed. In terms of units of 1, 2, and 3 units, it can be reproduced at double speed by displaying only 1 unit or 3 units. This approach can easily prevent problems caused by missing reference frames. However, if the frequency of IDR frames is low, for example, once IDR frames appear once per second (typically IDR frames appear once every 0.5 seconds), the picture appears smoothly and suddenly for 1 second. After the volume disappears, it may come out again for 1 second, and the 1 second volume may disappear.

Therefore, in the present invention, the original video is compressed as (IDR, P, B, B), (IDR, P, B, B), (IDR, P, B, B), (IDR, P, B, B). If present, do not play them in the form of (IDR, P, B, B), (Discard), (IDR, P, B, B), (Discard) during double-speed playback, and (IDR, P), (IDR). , P), (IDR, P), (IDR, P).

Then, if the IDR group is compressed as (IDR, P, B, B, P, B, B, P, B, B), there is a problem of how to divide it into units of IDR.

At this time, the easiest way of dividing by IDR unit is to extract the first part (IDR, P, B, B, P) from IDR group (IDR, P, B, B, P, B, B, P, B, B). Throw out the back part (B, B, P, B, B). If you divide the IDR unit (5 frames in the front, 5 frames in the back), the number of frames is divided in half, but it is not actually half. This is because the P frame and the B frame only compress the difference from the IDR frame, so the amount of data is smaller than the IDR frame. In other words, if the compressed data of the IDR frame is 50 KByte, it means that 20 KBytes for P frame and 10 KBytes for B frame. Therefore, the actual amount of data in IDR units divided by 5 frames in the front (IDR, P, B, B, P) totals 110KBytes (50 + 20 + 10 + 10 + 20), and 5 frames in the back ( B, B, P, B, B) total 60 KByets (10 + 10 + 20 + 10 + 10). When the divided IDR unit is transmitted, the data rate that the server sends to the client increases. Because the original video is sent 10 times, the total was 110 + 60 KBytes (average of 160 / 10KBytes per sheet), but when playing at double speed, it becomes 110KBytes (average of 110 / 5KBytes per sheet) for 5 transmissions, and the average transfer rate increases significantly. This occurs. Therefore, it is important to cut not only 10 sheets by 5 but also by considering the transmission rate.

Next, a method of generating IDR units will be described in more detail with reference to FIG. 4.

FIG. 4 is a flowchart illustrating a method of generating an IDR unit for trick play according to the present invention, assuming that there are 15 frames between an IDR frame and a next IDR frame, and F0 (IDR frame) and F1 to F15 (dependent). Frame) and F16 (next IDR frame).

Here, the trick play system generates IDR units so that the data size of frames to be generated in IDR units is maintained from IDR frame F0 to the next IDR frame F16 in order to maintain the transmission rate of the original content without putting a load on the server. It is about half of the data size of the frames. At this time, the trick play system takes the first half frame including the IDR frame and removes the second half frame as a frame to be generated in units of IDR, and in order to efficiently perform the operation, the stack is used (from the second half of the stack, More efficient because they can be removed in reverse order).

First, the trick play system initializes the number N1 of consecutive frames including the IDR frame and the size S1 of the consecutive compressed frames including the IDR frame in order to retrieve the start position IPos of the input IDR frame ( N1 = 0, S1 = 0) (401).

Thereafter, the trick play system searches (402) the start position (F1) of the frame and checks whether the current frame is the IDR frame (F16) (403). At this time, the trick play system searches for the start position F1 of the frame according to a method of searching for the start position of the frame specified in "ISO 14496-10".

As a result of the check 403, when the current frame is not the IDR frame F16, the trick play system accumulates information on the number N1 and the size S1 up to the current frame and stores it on the stack (N1 = N1 + 1, S1 = S1 + current frame size) 404, searching for the next frame (405) and repeating steps 403 to 405 until the retrieved frame is an IDR frame F16.

On the other hand, if the check result 403, the current frame is the IDR frame (F16), the trick play system performs a half of the frames between the IDR frame (F0) and the next IDR frame (F16) stored in the stack The erase frame number "N2" is set to N1 / 2, and the accumulated data size S2 of the erase frames is initialized (N2 = N1 / 2, S2 = 0) (406).

Here, the reason why the trick play system sets the number of removal frames "N2" to N1 / 2 is to perform half of the frames stored in the stack. At this time, the value of N1 (number of frames from F0 to F15) is 16, and the value of N2 (half of N1) is 8.

After that, the trick play system removes one of the second frames among the entire frames F0 to F15 stored in the stack, and decreases the number of removed frames 'N2' by one (N2 = N2-1) 408, and corresponding second frames. The process of accumulating and storing the data size S2 of (F15) (S2 = S2 + frame size) 409 is repeatedly performed until the number of removed frames 'N2' becomes 0 (step 407). At this time, since the value of N2 is 8, the process of "407" to "409" is performed a total of eight times.

Thereafter, the trick play system checks whether there is a frame referring to the removed late frames F8 to F15 among the first half frames F0 to F7 (410), and if the second half frames F8 to F15 are not referenced, If the frame is left as it is, and the latter frames F8 to F15 are referred to, the corresponding first half frame that has lost the reference is removed and the cumulative data size S2 of the removed frames is updated (411).

Then, the trick play system checks whether the cumulative data size S2 of the elimination frames exceeds half of the data size S1 of the entire frames F0 to F15 from the IDR frame F0 to the next IDR frame F16. (S1 < S2 * 2) 412 (i.e., verifying that the data size of the remaining frames is less than half the data size of the entire frames F0 to F15), the cumulative data size S2 of the eliminating frames is the IDR frame. If half of the data size S1 of the entire frames F0 to F15 from F0 to the next IDR frame F16 is exceeded (that is, the data size of the remaining frames is equal to the data size of the entire frames F0 to F15). If it is less than half), it is determined that the transmission rate of the original content can be maintained without putting a load on the server, and then, from IDR frame F0 to a frame that satisfies the condition is generated in IDR units (413).

On the other hand, if the check result 412, the data size (S2) of the removal frame is less than half of the data size (S1) of the entire frame (F0 to F15) from the IDR frame (F0) to the next IDR frame (F16) ( That is, if the data size of the remaining frames is more than half of the data size of the entire frames F0 to F15, the trick play system removes the remaining first half frames one by one from the second half to update the cumulative data size S2 of the removed frames. (414) It proceeds to "412" process and repeats.

In the method of generating an IDR unit for the trick play as described above, removing the latter frames among the frames between the two IDR frames is such that the IDR unit to be generated is approximately doubled and the sum of the data sizes of the first half frames. Adjusting not to exceed half of the data size of these entire frames is to ensure that the rate of IDR units to be generated does not exceed the rate of original content.

5 is a flowchart illustrating a trick play method using an IDR frame according to the present invention.

First, the trick play system receives a desired speed value S from the user (501), and determines a transmission condition based on the input speed value S (S502).

That is, the trick play system divides the input double speed value (S) by 2 (N = S / 2) (503) and subtracts 1 from the result (N) of dividing the double speed value (S) by 2 (N = N- 1) 504. The trick play system checks whether the value of N is '0' (505), and if the value of N is '0', decides to transmit by IDR unit (506), and if the value of N is not '0' It is determined as 'skip to the next IDR frame position' (507).

Thereafter, the trick play system generates an IDR unit to perform 'transfer' or 'skip' (508).

Here, the process of generating the IDR unit by the trick play system has been described in detail with reference to FIG. 4 and will not be described in detail.

Thereafter, the trick play system transmits the IDR unit generated in step “508” to the user terminal in a known streaming method according to the determination result of step “506” or “507” (509).

As described above, the present invention automatically generates a double speed IDR unit in the process of generating an IDR unit, and automatically adjusts the double speed at a double speed (step 1 double speed control), and according to the transmission conditions in the transmission process, "continuous transmission" (2 In the case of double speed) or "transfer-skip repetition" (for 4 times speed), etc., the speed is adjusted again (two speed control).

In the above, the method of generating an IDR unit for trick play according to the present invention has been described by applying the trick play system. However, the present invention is not limited thereto and may be applied to a system such as a video cassette recorder (VCR).

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention can be used in an H.264 VoD (Video on Demand) system.

1 is a diagram illustrating an embodiment of an IDR frame and a dependent frame used in the present invention;

2 is a diagram illustrating an embodiment of a trick play system using an IDR frame according to the present invention;

3 is an exemplary explanatory diagram illustrating a process of trick-playing an IDR frame and a dependent frame;

4 is a flowchart illustrating an embodiment of a method of generating an IDR unit for trick play according to the present invention;

5 is a flowchart illustrating a trick play method using an IDR frame according to the present invention.

* Explanation of symbols on the main parts of the drawing

21: double speed information input unit 22: transmission condition determination unit

23: IDR unit generation unit 24: transmission unit

Claims (15)

In the trick play system, Double speed information input means for receiving double speed information; Transmission condition determining means for determining a transmission condition in units of Instantaneous Decoding Refresh (IDR) based on the input double speed information; An IDR frame and an IDR frame among the dependent frames are configured for the trick play of the entire frame including a P-frame and a B-frame, which are compressed by the difference between the Instantaneous Decoding Refresh (IDR) frame and the IDR frame. IDR unit generation means for generating an IDR unit using up to a frame which is half of the total data amount; And Transmitting means for transmitting the IDR unit generated by the IDR unit generating means to an external user terminal according to the transmission condition determined by the transmission condition determining means Trick play system that includes. The method of claim 1, The transmission condition determining means, And determining the transmission or skipping in units of IDR based on a result of subtracting 1 from a value of a double speed inputted through the double speed information input unit. The method of claim 2, The transmission condition is, If the result of subtracting 1 from the result of dividing the double speed value by 2 is 0, it is determined as 'send by IDR unit', And a result of subtracting 1 from a result of dividing the double speed value by 2, wherein the value is 1 and skips by IDR units. delete The method according to any one of claims 1 to 3, The IDR unit generating means, Trick play system, characterized in that to remove from the dependent frame of the second half of the entire frame using a stack (Stack). In the trick play method, A speed information input step of receiving speed information; A transmission condition determining step of determining a transmission condition in an Instantaneous Decoding Refresh (IDR) unit based on the input double speed information; An IDR frame and an IDR frame among the dependent frames are configured for the trick play of the entire frame including a P-frame and a B-frame, which are compressed by the difference between the Instantaneous Decoding Refresh (IDR) frame and the IDR frame. An IDR unit generation step of generating an IDR unit using frames up to half of the total data amount; And Transmitting the IDR unit generated in the IDR unit generation step to the user terminal according to the transmission condition determined in the transmission condition determination step. The trick play method comprising a. The method of claim 6, The transmission condition determining step, And determining 'transmit' or 'skip' in IDR units according to a result of subtracting 1 from a value of a double speed inputted in the double speed information input step. The method of claim 7, wherein The transmission condition is, If the result of subtracting 1 from the result of dividing the double speed value by 2 is 0, it is determined as 'send by IDR unit', If the result of subtracting 1 from the result of dividing the double speed value by 2 is 1, the trick play method characterized in that it is determined as "skip by IDR unit." delete The method according to any one of claims 6 to 8, The IDR unit generation step, A first frame removing step of removing the late dependent frames such that half of the data amount is among the entire frames from the first IDR frame to the next second IDR frame; Generating a residual frame in double-speed-based IDR units by checking whether the data size of the remaining frame removed from the entire frame is less than half of the data size of the entire frame; And A second frame removing step of proceeding to the generating step after removing the frame referring to the removed late dependent frame among the remaining frames that are removed in the first frame removing step; The trick play method comprising more. The method of claim 10, The first frame removing step, And using a stack to remove half of the dependent frames from the latter half of the entire frame. In the method of generating an Instantaneous Decoding Refresh (IDR) unit for trick play, A first frame elimination that eliminates late dependent frames such that the amount of data is half of the entire frame from the first IDR frame to the second IDR frame following the first and second dependent frames of the P and B frames step; And An IDR unit generation step of generating a corresponding residual frame in IDR units by checking whether the data size of the remaining remaining frames removed from the entire frames is less than half of the data size of the entire frames IDR unit generation method comprising a. The method of claim 12, A second frame removing step of proceeding to generating the IDR unit after removing a frame referring to the removed late dependent frame among the remaining remaining frames removed in the first frame removing step; IDR unit generation method further comprising. The method according to claim 12 or 13, The IDR unit generation step, A checking step of checking whether a data size of the remaining remaining frames removed from the entire frame is less than half of the data size of the entire frame; If the data size of the remaining frame removed from the entire frame is more than half of the data size of the entire frame, as a result of the checking of the checking step, after removing the second frame from the remaining remaining frame and additionally removing the second frame Removing the third frame to proceed to; And If the data size of the remaining remaining frames removed from the entire frame is less than half of the data size of the entire frame as a result of the checking step, generating the corresponding residual frame in IDR units IDR unit generation method comprising a. The method of claim 14, The first frame removing step, A method of generating an IDR unit according to claim 1, wherein the second subframe of the half of the entire frames is removed using a stack.

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