KR101665853B1 - Video streaming and user prefix caching methods for the playback delay reduction in wireless video streaming service - Google Patents

Abstract

A method of playing back moving picture streaming according to an embodiment includes generating each prefix for a plurality of moving pictures and storing a part of the prefix considering the user's personal information in the generated prefix, The prefix including a predetermined number of packets from a first packet from a moving picture comprising a plurality of packets; And receiving a packet for the moving picture by requesting at least one moving picture including the stored prefix or the non-stored packet to an access point (AP).

Description

TECHNICAL FIELD [0001] The present invention relates to a video streaming method for reducing a playback delay and a method and a device for storing a user's packet,

The following description relates to a video streaming technique, and relates to a method and apparatus for storing packets.

The present invention is a research conducted with the support of the Korea Research Foundation as a fund of the government (future creation science department) in 2014. (No. 2011-0029329)

Recently, wireless data traffic has increased sharply due to a rapid increase in wireless mobile devices and related services. This trend is expected to continue for the time being. In addition, most of this rapidly growing data traffic is due to mobile video and is expected to account for more than 70% of total mobile data traffic by 2018. Accordingly, techniques for wireless communication and data processing techniques for improving the quality of mobile video streaming service are becoming important.

 Video streaming service is more sensitive to delay than existing web browsing or download service. In other words, for seamless video playback, the data must be transmitted in a stable and timely manner. In an effort to reduce the delay of data transmission, a proxy server 120 is utilized in a wired network. For example, as shown in FIG. 1, when the user 110 receives the image data directly from the main server 130 in response to a request for a YouTube image, a large amount of delay occurs because the user 110 receives the image data from a long distance. However, If the same video is requested next time, the data is transmitted from the proxy server 120 without going through the main server 130, so that the delay is greatly reduced and the main server 130 of the mobile station.

However, there are a lot of videos on the Internet, and the number of videos has increased significantly over time. In addition, since the video streaming service processes a large number of users, it saves only the famous images that have many requests. In this case, users who are interested in the stored popularity image can benefit from the stored image, but users who are interested in the image in the relatively unavailable category receive a large delay from the remote server. In addition, in the case of wireless transmission to a terminal, a new type of communication and image storing method is required because a transmission error is more likely to occur in a wireless channel than in a wired network and a large amount of power is required for wireless transmission.

Korean Patent Publication No. 2003-0049548 discloses a multimedia streaming method.

The moving picture streaming playback apparatus according to an exemplary embodiment of the present invention proposes a method of efficiently storing moving pictures in consideration of a user's taste and a viewing pattern.

A moving picture streaming reproducing apparatus according to an embodiment proposes a method of reproducing by minimizing a transmission error and power.

A method of playing back moving picture streaming according to an embodiment includes generating each prefix for a plurality of moving pictures and storing a part of the prefix considering the user's personal information in the generated prefix, The prefix including a predetermined number of packets from a first packet from a moving picture comprising a plurality of packets; And receiving a packet for the moving picture by requesting at least one moving picture including the stored prefix or the non-stored packet to an access point (AP).

According to an aspect of the present invention, the step of receiving a packet for the moving picture may include receiving, in order from the AP, the unstored packet, when requesting a moving picture for the stored prefix.

According to another aspect, the step of receiving a packet for the moving picture is repeatedly performed until the transmission of the packet to the AP succeeds as the packet transmission for the prefix fails based on the state of the wireless channel .

According to another aspect of the present invention, the step of receiving a packet for the moving image may include receiving the moving image in response to the stored packet from the AP when the moving image is requested.

According to another aspect of the present invention, the step of storing some prefixes of the prefixes for each moving picture considering the user's personal information may include storing a prefix of a plurality of moving pictures having a viewing probability higher than a predetermined reference, And storing the prefix for the memory in the memory via the wire.

According to another aspect of the present invention, the step of storing a prefix of a prefix for each moving picture considering the user's personal information includes storing the user's personal information, the transmission failure probability of the packet, And setting a size of the prefix based on at least one of the space and the space.

In an apparatus for playing streaming moving pictures according to an exemplary embodiment of the present invention, an apparatus for generating a plurality of prefixes for a plurality of moving pictures, and storing a part of prefixes in consideration of personal information of a user among the generated prefixes, - the prefix comprises a predetermined number of packets from a first packet from a moving picture comprising a plurality of packets; And a receiver for receiving a packet for the moving picture by requesting at least one moving picture including the stored prefix or the non-stored packet to an access point (AP).

According to an aspect of the present invention, the receiving unit may include receiving, in order from the AP, the unstored packet when requesting a moving picture for the stored prefix.

According to another aspect, the receiving unit may include repeatedly transmitting the packet to the AP until the packet transmission is successful as packet transmission for the prefix fails based on the state of the wireless channel.

According to another aspect of the present invention, the receiving unit may include receiving, in order from the AP, the stored packets when requesting a moving picture for the unsaved packets.

According to another aspect of the present invention, the storage unit may include storing a prefix for a plurality of moving pictures whose viewing probability is equal to or greater than a predetermined standard in a memory through a wired line as the terminal determines that the terminal is charged.

According to another aspect, the storage unit may include setting the size of the prefix based on at least one of the personal information of the user, the transmission failure probability of the packet, and the storage space of the prefix.

The moving picture streaming playback apparatus according to an exemplary embodiment can efficiently use a limited storage space by storing only a part of the moving picture. In addition, unlike the proxy server or the base station storing the viewing tendency for a plurality of users, the video streaming playback apparatus according to the embodiment stores the videos based on the taste and usage pattern of the user for each terminal, It is possible not only to utilize the storage space but also to guarantee the image quality of the user who mainly watches the non-image.

The moving picture streaming playback apparatus according to the embodiment updates the image file to be stored in the wired state at the time of charging, so that the power for wireless transmission can be reduced. Unlike the conventional data storing method in which the confirmed data is stored in preparation for the next request, the video streaming playback apparatus according to the embodiment is a video which is firstly played back by storing a moving picture in preparation for future viewing If it is stored, it can be watched seamlessly.

1 is a diagram illustrating an operation of reproducing a moving picture on a terminal through a proxy server.
2 is a block diagram showing a configuration of a video streaming playback apparatus according to an embodiment.
3 is a diagram illustrating a structure of a moving picture file of a moving picture streaming playback apparatus according to an embodiment.
FIG. 4 is a diagram illustrating an example of storing a prefix of a moving picture according to an embodiment.
5 is a diagram illustrating a moving picture streaming operation between an AP and a terminal according to an embodiment of the present invention.
FIG. 6 is a flowchart illustrating a moving image streaming playback method of the moving image streaming playback apparatus according to an embodiment.
FIG. 7 is a graph illustrating an average playback delay according to a size of a prefix of a moving picture streaming playback apparatus according to an exemplary embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing a configuration of a video streaming playback apparatus according to an embodiment.

The video streaming playback apparatus 200 according to the embodiment may include a processor 210, a bus 220, a network interface 230, The processor 210 may include a storage unit 211 and a reception unit 212. In other embodiments, the video streaming playback apparatus 200 may include more components than the components of FIG. However, there is no need to clearly illustrate most prior art components. For example, the video streaming playback apparatus 200 may include other components such as a display or a transceiver.

The memory 240 may be a computer-readable recording medium and may include a permanent mass storage device such as a random access memory (RAM), a read only memory (ROM), and a disk drive. Also, the memory 240 may store program codes for an operating system and a streaming playback routine. These software components may be loaded from a computer readable recording medium separate from the memory 240 using a drive mechanism (not shown). Such a computer-readable recording medium may include a computer-readable recording medium (not shown) such as a floppy drive, a disk, a tape, a DVD / CD-ROM drive, or a memory card. In other embodiments, the software components may be loaded into the memory 240 via the network interface 230 rather than from a computer readable recording medium.

The bus 220 may enable communication and data transmission between the components of the moving picture streaming playback apparatus 200. [ The bus 220 may be configured using a high-speed serial bus, a parallel bus, a Storage Area Network (SAN), and / or other suitable communication technology.

The network interface 230 may be a computer hardware component for connecting the video streaming playback apparatus 200 to a computer network. The network interface 230 may connect the video streaming playback apparatus 200 to a computer network via a wireless or wired connection.

The processor 210 may be configured to process instructions of a computer program by performing basic arithmetic, logic, and input / output operations of the video streaming playback apparatus 200. The instructions may be provided by the memory 240 or the network interface 230 and to the processor 210 via the bus 220. The processor 210 may be configured to execute program code for the storage unit 211 and the receiver unit 212. Such program code may be stored in a recording device such as memory 240. [

The storage unit 211 may generate a prefix for each of a plurality of moving pictures, and may store some prefixes considering the user's personal information among the generated prefixes. In this case, the prefix may mean that a predetermined number of packets are included in the moving picture composed of a plurality of packets from the first packet.

The storage unit 211 may store a prefix for a plurality of moving pictures whose viewing probability is equal to or higher than a predetermined reference value in the memory 240 through the wired line as the terminal determines that the terminal is charged. The storage unit 211 may set the size of the prefix based on at least one of the personal information of the user, the transmission failure probability of the packet, and the storage space of the prefix.

The receiving unit 212 can receive a packet for a moving picture by requesting at least one moving picture including a stored prefix or an un-stored packet to an access point (AP). When a motion picture for the stored prefix is requested, the receiving unit 212 can receive the packets in order from the AP in order from the AP. When the packet transmission to the prefix is failed based on the state of the wireless channel, It can be repeatedly transmitted. In addition, when the receiver 212 requests a moving picture for a packet that has not been stored, the receiver 212 can receive the packet from the AP in order.

3 is a diagram illustrating a structure of a moving picture file of a moving picture streaming playback apparatus according to an embodiment.

FIG. 3 shows a structure of a moving picture file. The moving picture may be composed of a plurality of packets, and the first plurality of packets, for example,? Packets may be defined as a prefix. Referring to FIG. 3, for example, each moving picture may be composed of a total of A packets 310, and a first packet, a second packet, and a third packet may be defined as a prefix 320. At this time, the size of the prefix can be changed according to the number of packets.

FIG. 4 is a diagram illustrating an example of storing a prefix of a moving picture according to an embodiment.

In the structure of the moving picture file, the size of the prefix may be set based on at least one of the user's personal information, the probability of failing to transmit the packet, and the storage space of the prefix.

For example, the terminal may store the prefixes of images with high viewing probability in a memory via a wired line when charging, in consideration of the user's taste and the usual viewing pattern. If there is a space in which the terminal can store M packets, it is possible to store a prefix for a plurality of videos among a total of M as shown in FIG.

5 is a diagram illustrating a moving picture streaming operation between an AP and a terminal according to an embodiment of the present invention.

It is assumed that the user requests a prefix of one of the plurality of videos stored as shown in FIG. The AP 510 can sequentially transmit an α + 1th packet that is not stored in the terminal, and the terminal 520 can receive the α + 1th packet sequentially from the AP 510. At this time, if the packet transmission fails because the state of the wireless channel is poor, the terminal 520 can repeatedly transmit the packet until the AP 510 succeeds.

If the user requests a video that does not store the prefix, the AP 510 can transmit the first packet to the terminal 520 in order, and the terminal 520 can receive the first packet from the AP 510. At this time, the terminal 520 can receive the packets from the first packet until success.

The moving picture streaming playback apparatus according to the embodiment can reduce the delay because the number of packets to be received through wireless transmission decreases as the size of the prefix increases as a moving picture stored in the terminal is requested.

On the other hand, the number of prefixes that can be stored in the limited memory of the terminal decreases as the size of the prefix increases, so that the probability that the stored moving pictures are requested may decrease. Accordingly, in order to minimize the playback interruption due to the transmission failure, the video streaming playback apparatus can set a proper prefix size in consideration of the storage space, viewing preference and pattern of the user, and the like. For example, the size of the prefix can be increased in proportion to the transmission failure probability and the size of the storage space, and the size of the prefix can be set to be larger as the viewing probability according to the user's taste and pattern is concentrated in some videos.

FIG. 6 is a flowchart illustrating a moving image streaming reproducing method of the moving image streaming reproducing apparatus according to an embodiment.

The video streaming playback method may be performed by the video streaming playback apparatus. The video streaming playback apparatus will be described with reference to FIGS. 2 to 5 as described above.

The moving picture streaming playback apparatus can generate a respective prefix for a plurality of moving pictures. Here, the prefix may include a first packet to a predetermined number of packets from a moving picture composed of a plurality of packets.

The video streaming playback apparatus may store 610 some prefixes considering the user's personal information among the generated prefixes. At this time, the personal information of the user may include consideration of a user's taste, a transmission failure probability of a packet, and a storage space of a prefix.

The video streaming playback apparatus can request 620 the AP with at least one image including a stored prefix or an unsaved packet.

The video streaming playback apparatus may determine 630 that the video streaming playback apparatus is a video request for the prefix stored in the terminal. At this time, if the moving picture streaming playback apparatus requests the moving picture for the stored prefix, the moving picture streaming playback apparatus can sequentially receive the unsaved packets from the AP (640). When the moving picture streaming playback apparatus requests a moving picture for a packet that is not a moving picture request for a stored prefix but a non-stored packet, the moving picture streaming playback apparatus can receive the moving picture packet from the AP in order (641).

FIG. 7 is a graph illustrating an average playback delay according to a size of a prefix of a moving picture streaming playback apparatus according to an exemplary embodiment.

It is assumed that the total number of videos is infinitely large and the request probability of each video clip follows the Weibull distribution. In other words, the probability that a moving picture streaming playback apparatus requests one of the top i moving pictures having a high probability of being requested by the user can be expressed by Equation (1).

&Quot; (1) "

와

는 각각 Weibull분포의 scaling 파라메터, shape 파라메터를 나타낸다. 이 파라메터들은 사용자의 시청 취향에 따라 다른 값을 갖는다. 무선 전송되는 패킷들은 각각 i.i.d. fading을 겪게 되어 사용자가 전송된 패킷을 무사히 수신할 확률을 P_e로 정의한다. 도 3 내지 도 5를 통해 설명한 방법으로 저장 공간을 사용할 경우, 사용자가 평균적으로 체감하는 재생 지연은 수학식 2와 같이 나타낼 수 있다. here

Wow

Represent the scaling parameter of the Weibull distribution and the shape parameter, respectively. These parameters have different values depending on the viewing preference of the user. Each packet of wireless transmission experiences iid fading, and defines the probability that the user can safely receive the transmitted packet as P _e . When the storage space is used in the method described with reference to FIGS. 3 to 5, the reproduction delay experienced by the user on an average can be expressed by Equation (2).

&Quot; (2) "

는 프리픽스가 저장되어 있는 동영상 중 하나를 사용자가 요청하는 사건을 나타내고 Q(x)는 Q-function을 나타낸다. 평균 지연 값의 근사치는 전체 전송 실패 횟수의 normal approximation을 통해 얻을 수 있다. 근사된 수식을 최소화 시키는

값을 구함으로써 평균 재생 지연을 최소화 시키는 최적의 프리픽스의 크기를 얻을 수 있다. 이때, 한 동영상을 구성하는 패킷 개수 A가 충분히 크다는 가정 하에 최적의 프리픽스의 크기는

=AP_e로 간소화 될 수 있으며, 10분짜리 YouTube 동영상이 약 17000개의 패킷들로 구성됨을 고려하였을 때 이 가정은 합당하다 할 수 있다. 이는 결국 최적의 프리픽스의 사이즈는 저장 공간 또는 분포의 변화에 영향을 받지 않고 간단하여 실제 시스템 상에 구현이 쉽다고 볼 수 있다. here

Denotes an event that the user requests one of the videos stored in the prefix, and Q (x) denotes the Q-function. An approximation of the average delay value can be obtained through the normal approximation of the total number of transmission failures. Minimize the approximated formula

It is possible to obtain the optimum size of the prefix that minimizes the average reproduction delay. At this time, assuming that the number of packets A constituting one moving picture is sufficiently large, the size of the optimal prefix is

= AP _e , and this assumption is reasonable given that a 10-minute YouTube video consists of about 17,000 packets. This means that the size of the optimal prefix can be easily implemented on an actual system without being affected by changes in storage space or distribution.

에 따른 평균 재생 지연 수치를 서로 다른 두 저장공간 (M=4A, 100A)에 대해 보여주고 있다. 이 저장 공간들은 각각 100MB, 2.5GB에 해당한다. 도 7에서의 실험 환경은 다음과 같다.7, the size of the prefix

(M = 4A, 100A), which are different from each other. These storage spaces correspond to 100MB and 2.5GB, respectively. The experimental environment in FIG. 7 is as follows.

The dotted line representing No caching in the graph represents the result when the storage space is not used, the solid line representing Simul is obtained from the mote-carlo simulation, another dotted line representing Normal Approx represents the normal approximation and the lower bound of Equation 2 The marker shows the lower bound of playback delay.

=AP_e=3400에서 지연 값이 최소화 됨을 확인할 수 있다.By confirming that the solid line representing Simul and another dotted line representing Normal Approx agree very much, it is confirmed that the error due to the normal approximation is very small, and the optimum prefix size

= AP _e = 3400, it can be confirmed that the delay value is minimized.

On the other hand, not given the storage space M minimum storage space in an environment that must be in the reproduction delay requirement of the user exists, to be smaller the average reproduction delay than D _max, be reserved for the delay requirements satisfaction is expressed as Equation (3) have.

&Quot; (3) "

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (12)

A method of playing streaming video,
Generating a prefix for each of a plurality of moving pictures and storing a part of the prefix in consideration of the user's personal information among the generated prefixes, A number of packets; And
Receiving a packet for the moving picture by requesting at least one moving picture including the stored prefix or the non-stored packet to an access point (AP)
Lt; / RTI >
Wherein the step of storing a part of the prefix in consideration of the personal information of the user comprises:
A prefix for a plurality of moving pictures whose viewing probability is equal to or greater than a predetermined reference value is stored in a memory via a wire and the at least one of a transmission failure probability of the user and a storage space of the prefix Setting a size of the prefix based on the size of the prefix
The method comprising the steps of: The method according to claim 1,
Wherein receiving the packet for the moving picture comprises:
When receiving a moving picture for the stored prefix, receiving packets from the AP in order from the unstored packet
The method comprising the steps of: 3. The method of claim 2,
Wherein receiving the packet for the moving picture comprises:
Repeating and transmitting a retransmission request until the packet transmission to the AP is successful for a packet that is not received by the terminal that reproduces a moving picture due to failure of packet transmission for the prefix based on a state of a wireless channel
The method comprising the steps of: The method according to claim 1,
Wherein receiving the packet for the moving picture comprises:
When receiving the moving picture for the unsaved packet, receiving the moving picture from the AP in order from the stored packet
The method comprising the steps of: delete delete An apparatus for playing streaming video,
A storing unit for storing a plurality of prefixes for a plurality of moving pictures and storing a part of the prefixes in consideration of the user's personal information among the generated prefixes, Comprising a predetermined number of packets; And
(AP) for requesting at least one moving picture including the stored prefix or the non-stored packet,
Lt; / RTI >
Wherein,
A prefix for a plurality of moving pictures whose viewing probability is equal to or greater than a predetermined reference value is stored in a memory via a wire and the at least one of a transmission failure probability of the user and a storage space of the prefix Based on the size of the prefix
Wherein the video streaming reproduction apparatus comprises: 8. The method of claim 7,
The receiver may further comprise:
When a moving picture for the stored prefix is requested,
Wherein the video streaming reproduction apparatus comprises: 9. The method of claim 8,
The receiver may further comprise:
A retransmission request is repeatedly transmitted until the packet transmission to the AP is successful for a packet that the terminal reproducing the moving picture fails to receive due to a failure in packet transmission for the prefix based on the state of the wireless channel
Wherein the video streaming reproduction apparatus comprises: 8. The method of claim 7,
The receiver may further comprise:
When the mobile terminal requests a moving picture for the unsaved packet,
Wherein the video streaming reproduction apparatus comprises: delete delete

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