JPH09252304A - Video distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drastically reduce cost required for a transmission line by accumulating and preserving an ATM cell received from a video server once in a video storage part in an access node, and allotting the accumulated ATM cell at proper timing. SOLUTION: In a near video on-demand system, before compressed video information resolved into the ATM cell is outputted from the video server 1, and is allotted directly to a set top box(STB) 4 connected to a TV set in each user home, one access node 3 is installed for every 8 subscribers, for instance. The access node 3 is provided with the video storage part and an allotment control part, and the cell received from the video server 1 is accumulated and preserved once here. The cell preserved here is allotted to the STB 4 of a user through an optical fiber 103 only at time selected by the user at the predetermined time (e.g. every 15min). Thus, traffic between the video server 1 and the access node 3 is reduced, and the cost required for the transmission lines 101, 102 and a sub-network 2, etc., is curtailed remarkably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video distribution system for transmitting video information including moving images (for example, movies) in real time.

[0002]

2. Description of the Related Art Conventionally, one of the video distribution systems of this type has been used.
As one of them, there is known a near video on demand system in which the same moving picture is shifted in time and transmitted to improve the convenience of the viewer. This system is, for example, the Technical Report of the Institute of Electronics, Information and Communication Engineers SSE94.
-99 "Traffic Design of ATM Switch with Multicast Function", its configuration is described.
This is shown in FIG.

As shown in FIG. 12, this near video on demand system includes a video server 1 as a source of movie programs and an optical fiber transmission line 101.
And a subscriber line termination device (SLT) 20 connected by an optical fiber transmission line 101 and a subscriber line 202 which is installed in each subscriber's house and is composed of an optical fiber or the like.
Optical network units (O
NU) 21, set-top box (STB) 4 connected to ONU 21 in each subscriber's home, and STB 4
And a television device (TV) 5 connected to the.

A digitally compressed movie program is stored in the video server 1, and this movie program is transmitted via the optical fiber transmission line 101 at a predetermined time.
It is designed to be transmitted to the LT 20. As the transmission protocol in this case, the ATM method is used in which the movie program is decomposed into ATM (asynchronous transmission mode) cells and transmitted. This method is recommended by the ATM forum and the like. The SLT 20 broadcasts the movie program to each optical fiber of the subscriber line 202.
The broadcast function is realized by the broadcast switching function of the ATM switch provided in the SLT 20. The movie program transmitted by broadcast is transmitted to the STB 4 via the ONU 21 in the subscriber's house where the subscriber line 202 terminates. The STB 4 takes out the data from the received ATM cell and reproduces the movie program. The reproduced movie program can be viewed on the TV 5.

In such a system, in the case of transmission by the near video on demand system, movie programs of the same content are shifted by a predetermined time and transmitted. Now, for example, the bandwidth (transmission rate) required to transmit one movie program is 6 Mbps, the broadcast time of the movie program is 2 hours, and 15 movie programs having the same content are used.
Staggered by minutes (that is, 00 minutes, 15 minutes, 30 minutes, 45 minutes, 60 minutes, 75 minutes from the basic start time, respectively)
If transmission is performed by shifting by 90 minutes, 90 minutes, and 105 minutes), the bandwidth required for transmission is 48 Mbps (= 6 Mbps x
8). Here, the number of patterns at the broadcast start time (here, eight patterns) will be referred to as the “phase number”. In this case, the band of 48 Mbps is the band consumed by the optical fiber transmission line 101 and the subscriber line 202.

FIG. 13 is an example showing the concept of the near video on demand system. In this example, one type of movie program having a broadcast time of 2 hours (the title is "Title 1") is transmitted in 15 phases at 8 phases. Specifically, the first broadcast starts at 20:00 and ends at 22:00, and the second broadcast starts at 20:15 and ends at 22:15. Similarly, transmission is performed at intervals of 15 minutes.

[0007]

However, in such a conventional near video on demand system, there is a problem that the required transmission band becomes extremely huge when the number of kinds of movie programs to be broadcast increases. there were. For example, if there are 20 types of movie programs, the required bandwidth is 960 Mbps (= 48 Mbps x 2).
0). This transmission band is an unrealistic value considering that the transmission band used by the subscriber line 202 is usually 156 Mbps, and even if this can be realized, it is economically very expensive. This will result in such a system. In addition, the optical fiber transmission line 101 between the video server 1 and the SLT 20 is required to have the same wide band as described above, and thus the video server 1 and the SLT 20 are required.
When the distance between the above and the above is large, the cost of the transmission line of the ATM backbone network connecting them becomes considerably large.

As described above, the conventional near video on
Since the demand system requires an extremely large transmission band according to the number of phases at the time of transmission, there is a problem that the transmission cost becomes huge in both the backbone network and the access network.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a video distribution system capable of significantly reducing the cost required for a transmission line as compared with the conventional system.

[0010]

According to a first aspect of the present invention, there is provided a video distribution system for storing a video signal and outputting the video signal using ATM cells according to a predetermined schedule. A set-top box and a television set installed in a user's house for extracting data from a received ATM cell and reproducing a video signal as an image, and an ATM cell output from the video server in the set-top box of each user's house. An access node for transmission is provided, and a video cell storage unit for accumulating and storing ATM cells received from the video server is provided in the access node.

In this video distribution system, the ATM cells received from the video server are temporarily stored and stored in the video cell storage section in the access node. Therefore, after this, the accumulated ATM cells can be delivered at an appropriate timing.

According to a second aspect of the present invention, in the video delivery system according to the first aspect, the access node delivers an ATM cell stored in the video cell storage unit to a user at a predetermined time. It is configured to do.

In this video distribution system, the ATM cells stored in the video cell storage section of the access node are distributed to the user at a predetermined time.

According to a third aspect of the present invention, in the video delivery system according to the first aspect, the access node stores in the video cell storage unit only at a time selected by a user among predetermined times. The configured ATM cell is configured to be delivered to the user.

In this video distribution system, the ATM cells stored in the video cell storage unit of the access node are distributed to the user only at the time selected by the user among the predetermined times.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a video distribution system according to an embodiment of the present invention. In this figure, the same components as those of the above-mentioned conventional example (FIG. 12) are designated by the same reference numerals, and the description thereof will be appropriately omitted.

This system comprises a video server 1 as a source of movie programs, an ATM subnetwork 2 connected to the video server 1 by an optical fiber transmission line 101, and an ATM subnetwork 2 by an optical fiber transmission line 102. Access node 3 and STB 4 installed in each subscriber's house and connected to access node 3 by optical fiber transmission line 103.
And a TV 5 connected to the STB 4 by the RGB cable 104 in each subscriber's house.

The transmission line between the access node 3 and the STB 4 is called an access network. The form of this access network usually differs from system to system, but in this embodiment, it is composed of the optical fiber transmission line 103. The number of STBs 4 that can be connected to the access node 3 can be expanded depending on the system scale, but this embodiment exemplifies a case of 8 users A to H.

Next, the structure of each part in FIG. 1 will be described.

FIG. 2 shows the configuration of the video server 1. The video server 1 includes a video data input unit 6
, A video data storage unit 7, an ATM cell conversion unit 8,
TM interface section 9 and control section 1 for controlling these
0.

The video data storage unit 7 stores a plurality of types of movies as digital data. The format of digital data is based on, for example, the MPEG (Moving Picture Coding Experts Group) system defined as an international standard. In this method, the image compression format is MPEG2, and this MPEG2 data is converted into MP2.
It is stored in the video data storage unit 7 in a state of being contained in a packet called an EG2 transport stream packet. Hereinafter, the video data storage unit 7 of the video server 1
The movie data stored in the above will be referred to as video data. The length of each movie is 2 hours and the transmission rate is 6M.
This will be described as bps.

In FIG. 2, the video data of each movie is input from the video data input unit 6, and the above-mentioned MPEG2 is used.
It is accumulated in the video data storage unit 7 in the form of transport stream packets. Each video data is controlled by the control unit 1.
0 is read from the video data storage unit 7 according to a schedule, and the read video data is ATM.
The cell assembling unit 8 accommodates the ATM cell (hereinafter, simply referred to as a cell).

In this case, a so-called "MPEG over ATM" standardized by the ATM forum is used as a cell format. This standard called "MPEG over ATM" uses the above-described MPEG2 transport stream packet as a type 5 ATM adaptation layer protocol.
(AAL5) is used to define a cell conversion method. Normally, two MPEG2 transport stream packets are decomposed into eight ATM cells, so the cell flow traffic is about 1.13 (= (53 × 8 / (188 × 2)) times that of the MPEG2 transport stream. In this embodiment, since the transmission rate of each video data stream is 6 Mbps, the cell flow traffic is about 6.77 Mbps, and the cell carrying the video data passes through the ATM interface unit 9. Then, it is designed to be output to the outside.

Although not shown, the ATM sub-network 2 includes an ATM line and an ATM switch for switching cells. The number of ATM switches may be one or plural. However, when both the video server 1 and the access node 3 are installed in the same premises, the ATM switch may be omitted.

FIG. 3 shows the configuration of the access node 3. This access node 3 is a backbone AT
M interface section 11, ATM switch section 12,
Access network ATM interface unit 13
A user information management unit 14, a video data cell storage unit 15, an ATM switch control unit 16, and a video data cell distribution control unit 17.

Backbone ATM interface unit 1
1 is connected to the ATM sub-network 2 and receives cells sent from the video server 1 and sent via the optical fiber transmission line 102. Then, the cell format of the received cell is inspected, and a normal cell is detected by the ATM switch unit 1.
It is designed to transfer to 2.

The ATM switch section 12 includes a backbone ATM interface section 11, an access network ATM interface section 13, a user information management section 14,
The video data cell storage unit 15 and the ATM switch control unit 16 are connected to each other, and cells are switched between these units.

The access network ATM interface unit 13 is connected to the optical fiber transmission line 103, which is an access network, and transmits cells to the STB 4 of each user.

Upon receiving the request from each user, the user information management section 14 determines whether or not the request can be accepted. The request accepted here is stored in a database (not shown) in the user information management unit 14.

The video data cell storage unit 15 is adapted to receive and store cells containing video data sent from the video server 1.

The ATM switch control section 16 is for setting the connection for switching of the ATM switch section 12 based on the setting of the user information management section 14.

The video data cell distribution control unit 17 controls the video data cell storage unit 15 based on the information of the user information management unit 14.

FIG. 4 shows the structure of the STB 4.
As shown in this figure, the STB 4 includes a network interface module 18 and a set top unit 1.
9 is provided and the data is taken out from the received cell to play the movie program. The network interface module 18 uses the optical fiber transmission line 1
It is connected to the access node 3 by one-to-one communication with the access terminal 03 and has a cell transmission / reception function and an ATM adaptation layer (AAL) processing function. The set top unit 19 has a function of processing an MPEG2 transport stream packet and reproducing a video signal and an audio signal and sending them to the TV 5. This allows the user to watch the movie on the TV 5.

Next, the near video with the above-mentioned structure
The operation of the on-demand system will be described.

Each user notifies the STB 4 of the title of the movie he / she wants to watch and the desired broadcast time by using, for example, a wireless remote controller. Broadcast time is selected from a predetermined schedule.

FIG. 5 shows an example of the broadcast schedule. This schedule is for July 20, 1996, and 10 movie titles (“Title 1” to “Title 10”) are listed. Each movie will be broadcast for 2 hours. The number of broadcast times (phase number) of each movie is 8, and "broadcast start reference time" + "difference time"
The time calculated by is the broadcast start time of each phase. For example, in the case of the movie “Title 1”, 18:00, 1
8:15, 18:30, 18:45, 19:00, 1
There are eight phases of 9:15, 19:30, and 19:45. In this table, program codes are displayed for each broadcast time (phase) of each movie. For example, the "program code" of the program of the movie "Title 1" started at 18:30 is "0102".

The user looks at this broadcast schedule table, selects the desired movie title and broadcast time, and notifies the STB 4 of the corresponding program code. Now, when the user A selects a program of the movie “Title 1” that starts broadcasting at 18:30 from the above-mentioned broadcast schedule table, the user A selects “01” as the “program code”.
02 ”to STB4. The STB 4 accommodates the input program code in the cell, and the optical fiber transmission line 1
It transmits to the access node 3 via 03.

In the access node 3, the access network ATM interface unit 13 causes the STB 4
Receive cells from. The ATM switch unit 12 transfers the cell received by the access network ATM interface unit 13 to the user information management unit 14. The user information management unit 14 checks the request from the user A written in the cell and registers it in the database in the user information management unit 14.

FIG. 6 shows the contents of the user request information registered in the database in the user information management section 14. As shown in this figure, the user name making the request is registered in this database in association with each movie title name, broadcast start date and time, and program code. For example, users A and C are registered as users who have notified the program code “0102” whose movie title name is “Title 1” and whose broadcast start date and time is “July 20th 18:30”.
In addition, program codes “0100”, “0103”,
“0104” corresponds to users B, F, and
D has been requested, and the program code “0107” has been requested by users E and H. Program code "0101", "0105"
And "0106" have not been requested by any user.

On the other hand, the video server 1 starts transmitting each movie at each "broadcast start reference time" shown in FIG. 5 regardless of the request status (FIG. 6) managed by the user information management section 14. . That is, for the movie of “Title 1”, only one broadcast is transmitted at 18:00.
The movie is transmitted by ATM (that is, MPEG2 transport stream packets are divided into cells using AAL5). The transmitted cell is sent to the access node 3 through the ATM subnetwork 2.

At the access node 3, the backbone system A
The TM interface unit 11 receives the cell from the video server 1. The received cell is the ATM switch unit 1
2 is transferred. The ATM switch unit 12 transfers cells to the video data cell storage unit 15 or the access network ATM interface unit 13 or both according to an instruction from the ATM switch control unit 16.

The ATM switch control unit 16 is based on the information from the user information management unit 14 and the ATM switch unit 1
The communication channel in 2 is set.

On the other hand, the user information management unit 14 creates the ATM switch control information as shown in FIGS. 7 and 8 according to the above user request information.

As shown in FIG. 7, the ATM switch control information includes channel type, transmission band, multicast identification number, channel identifier (input port), channel identifier (output port), channel corresponding to each program code. It consists of the set date and time and the channel release date and time. For example, for the program with the program code “0102” requested by the user A, the channel type is “multicast”, the multicast identification number is “2”, the transmission band is “6 Mbps”, and the port number of the channel identifier (input port) is “ 30 ", the virtual path identifier (VPI) is" 10 ", the virtual channel identifier (VCI) is" 17 ", the channel setting date and time is" July 20, 18:30 ", and the channel release date and time is" July 20 ".
20:30 on the day ".

Since the program code “0102” is requested by the users A and C, the channel type is “multicast”. For multicast communication, channel identifier (output port)
Is omitted and the multicast identification number is set instead. Program code "010
Since “3” and “0104” are both requested by only one user (user F or user D), the channel type is “single cast”, and the channel identifier (input port) and channel identifier (output port) Both are set and no multicast identification number is set. Program code is "0101", "0"
The programs "105" and "0106" are not transmitted because there is no request from the user. This is indicated by "*" in the channel type column. The program with the program code “0100” is a request from only one user (user B), but the broadcast time of the movie matches the “broadcast start reference time”, and the video server 1
Cell from user B and video data cell storage unit 1
5, the channel type is set to "multicast" and the multicast identification number is set to "1". For the program code in which the channel type is set to "multicast", the "multicast setting information" provided from the user information management unit 14 by referring to the multicast identification number
The channel is set based on (FIG. 8).

FIG. 8 shows an example of “multicast setting information” provided by the user information management unit 14. As shown in this figure, in the multicast setting information, the port number on the output side of the ATM switch unit 12, VPI, and VCI are set for each multicast identification number. For example, multicast identification number "1"
Indicates channel 1 set to “port = 21, VPI = 17, VCI = 11” and “port = 30, VPI =
2, the VCI = 16 ”is set to be multicast. The number that can be multicast depends on the scale of the ATM switch unit 12,
It is not limited to the case where the number of multicasts is 2 as in this embodiment.

Then, the ATM switch control section 16 sets the channel of the ATM switch section 12 using the ATM switch control information shown in FIGS. 7 and 8.

FIG. 9 shows the channel setting state of the ATM switch section 12, which shows each port number and V of each channel.
PI and VCI are shown. As shown in this figure, the ATM switch unit 12 and the backbone ATM interface unit 11 are connected using the port 10 of the ATM switch unit 12, and the ATM switch unit 12 and the video data cell storage unit 15 are connected. Are connected using port 30. The ATM switch unit 12 and each user (S
Ports 20-27 are used for connection with TB4). The ATM switch unit 12 is also connected to the user information management unit 14 by an ATM line, but it is omitted in FIG. The port 26 is a port connected to the STB 4 of the user G, but since there is no request from the user G, the channel is not set.

After the above settings are made, the actual movie is transmitted. Hereinafter, the operation will be described focusing on the flow of movie data.

First, from the video server 1 "title 1"
A cell with a movie (the program code is "0100"
Cell) is output at 18:00. The cell is 6.77
It is sent at a fixed rate of Mbps traffic for 2 hours. The values of VPI and VCI attached to the cell are preset for each movie. The cell transmitted by the video server 1 is an optical fiber transmission line 101,
The port 10 of the access node 3 is reached via the ATM subnetwork 2 and the optical fiber transmission line 102.
VPI of cell that has reached port 10 of access node 3
And VCI values are typically ATM subnetwork 2
Has been changed within. In this example, as shown in FIG. 7, it is assumed that VPI = 7 and VCI = 10.

In the access node 3, since the channel setting as shown in FIG. 9 is made in the ATM switch section 12, the program code reaching the port 10 =
The cell of “0100”, VPI = 7, and VCI = 10 is multicast to the port 21 and the port 30. The cell output to the port 21 is transmitted to the STB 4 of the user B as a cell having VPI = 17 and VCI = 11, and the port 30
The cell output to the video data cell storage unit 15 is output as a cell having VPI = 2 and VCI = 16. The STB 4 of the user B takes out the MPEG2 transport stream packet from the received cell by the network interface module 18, and further reproduces the video signal and the audio signal from the MPEG2 transport stream packet by the set top unit 19.
The reproduced video signal and audio signal are sent to the TV 5. As a result, the unit B can watch the movie of “Title 1” from the designated 18:00.

On the other hand, the cell output to the port 30 is sent to the video data cell storage unit 15 and stored in the cell form. The video data cell distribution control unit 17 manages the cells stored in the video data cell storage unit 15 based on the information from the user information management unit 14.

From the user information management unit 14 to the video data cell distribution control unit 17, the video data cell storage unit control information having the contents shown in FIG. 10 is sent. This information includes the program name, data capacity, data storage period, and the like. The video data cell distribution control unit 17 determines the storage address of each program based on this information.

The user information management unit 14 further sends the video data cell storage unit control information having the contents shown in FIG. 11 to the video data cell distribution control unit 17. This information includes the date and title of each program, VPI and VCI values and input start times for input cells, and VPI and VC for output cells.
The value of I and the output start time are included.

The video data cell storage unit 15 is a cell on which the movie of "Title 1" received from the ATM switch unit 12 is placed (the above VPI = 2 and VCI = 16 cells).
Is stored in the storage area assigned to the storage address “001” by using the above-mentioned video data cell storage control information (FIGS. 10 and 11) held by the video data cell distribution control unit 17.

The cells stored in the video data cell storage unit 15 are output at a designated time based on the video data cell storage unit control information shown in FIG. The traffic at the time of output is the same as the traffic sent by the video server 1, that is, a fixed rate of 6.77 Mbps. The payload of the cell when sent from the video data cell storage unit 15 is the same as that of the video data cell storage unit 15, but the VPI and VCI values of the cell header are specified by the video data cell storage unit control information in FIG. It is rewritten to the specified value. At this time, the cell in which the movie of "Title 1" is stored in the video data cell storage unit 15 is not modified or deleted.

The cell on which the movie of "Title 1" is placed, according to the control information of the video data cell storage section shown in FIG. 11, according to the above procedure, first VPI = 1 at 18:30.
It is output to the ATM switch unit 12 as a cell of 0, VCI = 17. The ATM switch unit 12 sets this cell to VPI = 7 for the port 20 as shown in FIG.
As a cell with VCI = 10, VP is applied to port 22.
Broadcast as a cell with I = 28 and VCI = 12. The cell output to port 20 is sent to STB4 of user A, and the cell output to port 22 is STB4 of user C.
Sent to As a result, the users A and C can start watching the movie of “Title 1” from the desired time of 18:30.

Similarly, the cell in which the movie of "Title 1" is placed follows the video data cell storage unit control information shown in FIG. 11 at VPI = 10 and VCI = 1 at 18:45.
8 cells are output to the ATM switch unit 12. A
The TM switch unit 12 transmits this cell to the port 25 as a cell with VPI = 51 and VCI = 15, as shown in FIG. The cell output to the port 25 is sent to the STB 4 of the user F. Thereby, the user F can start watching the movie of “Title 1” from the desired time of 18:45.

Similarly, the cell on which the movie of "Title 1" is placed has VPI = 10 and VCI = 1 at 19:00 according to the video data cell storage unit control information shown in FIG.
9 cells are output to the ATM switch unit 12. A
The TM switch unit 12 transmits this cell to the port 23 as a cell with VPI = 39 and VCI = 13, as shown in FIG. The cell output to the port 23 is sent to the STB 4 of the user D. Thereby, the user D can start watching the movie of “Title 1” from the desired time of 19:00.

Similarly, the cell on which the movie of "Title 1" is placed has VPI = 10 and VCI = 2 at 19:45 in accordance with the video data cell storage unit control information shown in FIG.
It is output to the ATM switch unit 12 as a cell of 0. A
As shown in FIG. 9, the TM switch unit 12 sends this cell to the port 24 with VPI = 40 and VCI = 14.
Cell of VPI = 73, V for port 27
It is transmitted as a cell of CI = 17. The cell output to port 24 is sent to STB4 of user E, and the cell output to port 27 is sent to STB4 of user H. As a result, the users E and H can start watching the movie of "Title 1" from 19:45, which is the desired time.

Although the present invention has been described above with reference to some embodiments, the present invention is not limited to these embodiments, and various modifications can be made within the equivalent range. For example, in the above-described embodiment, the cells of the video data cell storage unit 15 are distributed in response to each user's request. However, each user does not make a request, and all the movies are sent to all the users. Of course, it may be configured to transmit at the phase of.

[0063]

As described above, according to the video distribution system of the present invention, the ATM cells received from the video server are once stored and stored in the video cell storage section in the access node. The accumulated ATM
It becomes possible to deliver cells at an appropriate timing.

Particularly, according to the video delivery system of the third aspect, the ATM cells accumulated in the video cell storage unit in the access node are delivered to the user only at the time selected by the user among the predetermined times. As a result, it is possible to reduce the traffic between the video server and the access node and also reduce the traffic between the access node and the set-top box in each user's house. Therefore, there is an effect that the cost required for the transmission path can be significantly reduced as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video distribution system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a video server.

FIG. 3 is a block diagram showing a configuration of an access node.

FIG. 4 is a block diagram showing a configuration of an STB (set top box).

FIG. 5 is a diagram illustrating an example of a near video on demand broadcast schedule.

FIG. 6 is a diagram showing a request status of a user.

7 is a diagram showing an example of ATM switch control information created by a user information management unit in FIG.

FIG. 8 is a diagram showing an example of ATM switch control information created by a user information management unit in FIG.

9 is a diagram illustrating an example of channel setting contents of the ATM switch unit in FIG.

10 is a diagram showing an example of video data cell storage unit control information created by a user information management unit in FIG.

11 is a diagram illustrating an example of video data cell storage unit control information created by a user information management unit in FIG.

FIG. 12 is a block diagram showing a configuration of a conventional near video on demand system.

FIG. 13 is a diagram showing a concept of a near video on demand system.

[Explanation of symbols]

1 video server, 2 ATM subnetwork, 3
Access node, 4 STB, 5 television device, 6
Video data input section, 7 Video data storage section, 8
ATM cell conversion section, 9 ATM interface section, 10
Control unit, 11 backbone ATM interface unit,
12 ATM switch section, 13 access network interface section, 14 user information management section, 15
Video data cell storage unit, 16 ATM switch control unit, 101, 102, 103 optical fiber transmission line.

Claims (3)

[Claims] 1. A video server that stores video signals and outputs the video signals using ATM cells according to a predetermined schedule, and a data server that is installed in each user's house and extracts data from the received ATM cells. A set-top box and a television device for reproducing a video signal as a video image by using an access node for transmitting an ATM cell output from the video server to the set-top box at each user's house. A video distribution system comprising a video cell storage unit for accumulating and storing ATM cells received from the video server. 2. The video distribution system according to claim 1, wherein the access node distributes the ATM cells stored in the video cell storage unit to a user at a predetermined time. 3. The access node delivers the ATM cell stored in the video cell storage unit to the user only at a time selected by the user among predetermined times. The described video distribution system.