JPH06326983A - Digital video distributing system - Google Patents

Abstract

PURPOSE:To start the video source distributing service within a certain time after each service request by providing a video, distributing center device with a means which reads out video sources from a high-speed video medium, where video sources are stored, at n-fold reproducing speed in a user terminal. CONSTITUTION:When the service request is issued from one user terminal 8 to the same video source at intervals of an approximately fixed time, n read pointers can be set for a source file 4 because the high-speed video source medium has n-fold transfer capability of the video reproducing speed in the user terminal. That is, the video source file is divided into (n), and the read position to one user terminal is selected from n painters. When one terminal requests the service to the same video source approximately simultaneously, a registered group transfer address management table 7 is transferred to a high-speed communication network 9, and group transfer is requested. When requests are issued to the same video source beyond the transfer capability of one video source medium, an empty medium is selected to copy the file in the same manner, and thus, the video source is distributed within a prescribed time.

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 supplying high-definition video to a plurality of user terminals via a high-speed digital communication network, and more particularly, to the same video media source on demand from a plurality of user terminals. The present invention relates to a digital video distribution system for distributing a requested media source within a predetermined response time when service requests are concentrated.

[0002]

2. Description of the Related Art As an example of a conventional high-definition video distribution system, "Special Issue on Image Communication: Flowering, New Image Communication System" (NTT Technology Journal, 1989.6, pp. 2)
There is a moving picture information system described in 3-29).
As described in this document, in the conventional technology (FIG. 3), moving image information according to the purpose of use is provided from the center device 1 to each terminal via the line connection device. The line is a dedicated line between the center and the user terminal 8, and because one-to-one communication is performed, the video signal transferred through the line is an analog signal, and the high-definition video source has the same time as the reproduction time. Since it is read from file 4, one video source (for example, a VT suitable for a long time that is used like a library)
In the case where multiple user terminals simultaneously access R files, etc., no consideration other than broadcasting is taken into consideration.

Therefore, in the prior art, even if a plurality of users access the same video source that is frequently used at the same time, only the terminal permitted to use by the center can use it, and the other terminals can use it first. There is a drawback that the user must wait until the access from the terminal is released or cancel the use. Further, even if a plurality of video sources are prepared, the number of terminals that can simultaneously use the same video source is limited.

[0004]

Since the above-mentioned conventional high-definition video distribution system provides high-definition video on a one-to-one basis between a center device and a user terminal via a dedicated line, a plurality of video signals can be simultaneously transmitted to the same video source. If there is a service request from a user terminal, one or a part of the terminals can be serviced but the remaining user terminals must wait until one of the terminals releases the access or give up the access. There was a problem in that it would not happen.

An object of the present invention is to provide the same video source to all terminals that have requested a service within a fixed time without limiting the number of terminals even if a plurality of user terminals request the service to the same video source at the same time. It is to provide a high-definition video distribution system capable of providing a distribution service.

[0006]

A first method for achieving the above object is to allow a simultaneous access in a video distribution center apparatus so that a user terminal can be operated from a first high speed video medium storing a video source. And a means for reading out the video source at n times the reproduction speed.

A second method for achieving the above object is
In the video distribution center apparatus, when the maximum number of user terminals Nmax that can be serviced by one video media file is exceeded and a plurality of user terminals simultaneously request service for the same video media, the (N-1) th user terminal Means to copy the video source from the first high-speed medium to the second high-speed video medium for extended service in advance by using the Nmax-th channel when the same video source is accessed from And

A third method for achieving the above object is as follows:
In a video distribution center device, when a plurality of user terminals simultaneously request a service to the same video medium, a plurality of user terminals that have requested a service to the same video medium within a fixed time are set as a simultaneous access group. It is characterized in that a means for collectively managing is provided.

[0009]

In the high-definition video distribution system according to the present invention, when a plurality of user terminals make a service request to the same video source at random in the same time zone, a digital compressed video source for a predetermined reproduction time is supplied. N of the reproduction time
Since it is possible to read at twice the high speed, it is possible to easily specify n reading positions for the same video source,
It is possible to easily provide the same video source data having different read positions to n user terminals within the reproduction time. Further, in the high-definition video distribution system of the present invention, a plurality of user terminals that have requested a service to the same video medium within a fixed time can be collectively managed as one simultaneous access group, so that a high-speed digital communication network can be realized. It is possible to easily perform a multicast to the plurality of user terminals via the.

[0010]

1 is a block diagram of a first embodiment according to the present invention. Reference numeral 1 is a video distribution service center device including a video distribution controller 2, a communication adapter 3, a video source file group 4, and an extended service file group 5.
The video distribution service center device 5 responds to the on-demand service request from the user terminal 8 with multimedia information including video, data, and audio to the i user terminals 81 to 8i via the high-speed digital communication network 9. And transfer at high speed.

For the sake of simplicity, the high-definition video distribution service will be described in detail, and the description of data and audio will be omitted because they operate similarly to video information.

First, it is assumed that the transfer capability from one high-speed video source medium is n times the reproduction speed at each user terminal. At this time, (1) i user terminals 81 to 8
If there are service requests from i to the same video source at almost constant intervals (2) If i user terminals make service requests to the same video source at almost the same time, (3) 1
Description will be given separately when there is a service request for the same video source that exceeds the transfer capability of the video source media of one unit.

(I) When there is a service request from the i user terminals to the same video source at substantially constant intervals In this case, i ≦ n. Since the high-speed video source media has a transfer capacity n times as fast as the video playback speed on the user terminal, n source file read pointers can be set. That is, in consideration of the response time at the user terminal, if the video source file is divided into n with the optimum length, it is possible to always read from n pointers. Therefore, the reading position to i user terminals is selected from n pointers. All you have to do is

For example, the reproduction time at the user terminal is 12
When the 0 minute video source is in the video source file of the video distribution center and the maximum wait time for waiting the user after requesting the service is 3 minutes, the 120 minute video source can be divided into 40 and the read pointer can be set. If a high-speed video source media that can sequentially read out video sources for only 3 minutes from all pointers within a minute is installed as a center device, it can be played on the user terminal from any access point after waiting 3 minutes. Becomes If the video source media is not so fast, n <40
In the case of i, if i ≦ n, i read pointers corresponding to the user can be set, and by selecting any of 40 pointers, the video source of the read point requested within 3 minutes Can be played on each terminal.

(II) When i user terminals make a service request to the same video source at almost the same time Next, when i user terminals access the same video source at almost the same time, the group transfer provided in the video distribution controller is performed. The source address and destination address for group transfer are registered in the address management table, the registered group transfer address management table is transferred to the high-speed digital communication network, and the group transfer is requested to distribute the video to each service terminal at the same time. To do.

(III) When there is a service request for the same video source that exceeds the transfer capability of one video source medium When there is a service request for the same video source that exceeds the transfer capability of one video source medium, That is, when i ≧ n. First, it is assumed that access requests to the same video medium are randomly made, that is, in the above example, at an interval of about 3 minutes which is the maximum wait time, from more than n user terminals to the same video medium.

In the present invention, (n-1) is used for the same video medium.
When there is a service request from one user terminal, an empty medium is selected from the extended service file group, and the image source is copied from the image source medium to the selected empty medium. Access to the copied video media is also (n-
1) When the number of units becomes one, select another empty medium and copy it in the same way, so that even if service requests concentrate on the same video source, empty files will be added to the extended service file group. As long as the number of user terminals to the same video medium is increased, the video source for which a service request is made can be distributed within a predetermined time period. Also, when service requests are concentrated almost at the same time, it can be dealt with by using the multicast function of the high-speed digital communication network.
This is possible by executing the same control as in I).

Next, the principle of the video data distribution procedure according to the present invention will be described with reference to FIG. As shown in FIG. 2, video service requests may be concentrated from each user terminal 8 or may be accessed at random intervals. First, a case where video service requests are concentrated will be described. In this case, if it can be regarded as the start at the same time even if the access is concentrated, the high-speed digital communication network 9
Using the multicast function of, the video distribution service center device only needs to transfer once.

However, if the service requests to the same source have different service start times, it is necessary to transfer as many service requests having different start times as shown in FIG. 2A, but in this case as well. Since the video source file has a speed N times as fast as the reproduction speed, high-speed transfer is possible within the transfer capacity of the network.

If the access is considered random, then
As shown in FIG. 2B, since the video source is read out at a high speed immediately after the service request and is sequentially transferred at a high speed via the network, the response time seen on the network seems rather fast.

[0021]

According to the first effect of the present invention, when the video distribution center apparatus makes a service request at random from a plurality of terminals in the same time zone, each terminal requests each service request within a certain time. A video distribution system that can start a video source distribution service can be provided.

According to the second effect of the present invention, the same video service is requested at the same time when there is a service request from a plurality of user terminals exceeding the maximum number Nmax of simultaneous user service that can be simultaneously distributed for one video source medium. When the number of user terminals reaches (Nmax-1), empty media is allocated from the extended service file group, and Nmax
A video distribution system capable of performing a video distribution service within a predetermined time from a service request even if the access to the same video media exceeds Nmax by copying the video source in advance by using the second channel. Can be provided. According to the third effect of the present invention, even when transfer requests are made from a plurality of user terminals at approximately the same time, a video that can be simultaneously distributed to a plurality of user terminals that are considered to be simultaneously accessed within a certain time by the multicast function. A distribution system can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment according to the present invention.

FIG. 2 is an explanatory view of the principle of a video reading procedure according to the present invention.

FIG. 3 is a block diagram of a conventional example.

[Explanation of symbols]

1 ... Video distribution service center device, 2 ... Video distribution controller, 3 ... High-speed digital communication adapter, 4 ... High-definition video source file, 5 ... Extended service file group, 6
... Transfer address management table, 7 ... Group transfer address management table, 8, 81 to 8i ... User terminal, 9 ... High-speed digital communication network.

Claims (4)

[Claims] 1. A video distribution center device of a video distribution system for supplying high-definition video to a plurality of user terminals via a high-speed digital communication network, wherein the plurality of digital compressed video sources stored in a high-speed medium are used for the plurality of digital compressed video sources. When there is a service request from the user terminal at the same time, the video data corresponding to a predetermined reproduction time corresponding to a plurality of read positions designated for each user can be reproduced at a speed higher than N times the reproduction speed of the user terminal. Read out, and the read out video data is maximum N for the user terminal
A digital video distribution system characterized in that video is distributed in real time by dividing into channels and sequentially transmitting to the user terminal by the reproduction start time of the next video data. 2. The maximum permissible number of channels of one medium with respect to the first high-speed medium is Nma according to claim 1.
When service requests are made to the same video source from users exceeding x at the same time, when service requests are sent from (Nmax-1) user terminals, the Nmax-th time slot is used for the second high-speed media group. A digital video distribution for distributing the video source in real time to the remaining users who have exceeded the maximum allowable number of channels Nmax of one medium by selecting an empty high-speed medium and copying the video source. method. 3. The service request from the user to the same video source at the same time as the n-th (n ≧ 1) high-speed medium released to the user according to claim 1, which exceeds the maximum allowable channel number Nmax of one medium. When a service request is made to the high-speed medium from (Nmax-1) user terminals, an empty high-speed medium is selected from the second high-speed media group as the (n + 1) th high-speed medium. Select as the medium, Nmax of the high-speed media
By copying the video source using the th time slot, the (n + 1) th high speed medium is allocated to the remaining users who have exceeded the maximum allowable channel number Nmax of the n th high speed medium, A digital video distribution system that can distribute the video source in real time. 4. A digital video distribution system according to claim 1, wherein users who have randomly requested to read the same video within a fixed time are collectively managed as a simultaneous access group, and multicast-transferred to a plurality of users.