JPH1032790A - Video-on demand system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a real-time image by preventing the registration updating request and reproducing request of video contents from being interferred. SOLUTION: A video data storage part 5 stores the video data of various video contents. The video data are stored in the video data storage part 5 while being divided into plural blocks more than four at least. Concerning the plural divided blocks, an updating block managing part 6 successively and cyclically performs the registration of new video data into the video data storage part 5 and the update of registered video data to new data in prescribed order. In the case of accessing the video data stored in the video data storage part 5 corresponding to the demand of client PC 4A-4X, the regenerative block managing part 7 performs access so as not to collide with the file updated by a video register server 2 according to the updated block managing part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video-on-demand (VO) for providing video information according to a user's request.
D: video on demand) system, and more particularly to a video on demand system that efficiently provides real-time video.

[0002]

2. Description of the Related Art In a video-on-demand system, a video-on-demand (VOD) server stores video files composed of video data such as moving pictures of various video contents. The registration of the video content to the VOD server is performed by the video registration server. VOD
The server is a personal computer (hereinafter, referred to as "PC") operated by a user.
In response to a request from the client terminal, the video file is transmitted and played back to the client terminal, thereby providing the requested video content to the user. In recent years, MPEG (Mo
The compression efficiency of video contents is also increased by applying a video data compression method such as the Motion Picture Experts Group method.

[0003] In such a video-on-demand system, it is impossible to perform an operation in which a registration update request from the video registration server and a video reproduction request from the client terminal collide with each other for the same video file. That is, the content of the video file being reproduced on the client terminal cannot be updated by the video registration server. Further, the contents of the video file whose registration is being updated by the video registration server cannot be reproduced even if requested by the client terminal.

Therefore, in many conventional video-on-demand systems, registration and update of video content by the video registration server are performed during a period (time) during which service to the client terminal is blocked. That is,
Many video-on-demand systems employ a service form in which new registration or updating of video content is not performed by the video registration server during a service period (time) to a client terminal.

[0005]

As described above, in the conventional video-on-demand system, the content of the video file being reproduced cannot be updated by the video registration server, and the content of the video file being registered and updated is not updated. The contents cannot be reproduced even if requested by the client terminal. Therefore, in many conventional video-on-demand systems, registration and updating of video content by the video registration server are performed during a period in which services are closed, and new registration and updating of video content are performed during a service period to a client terminal. Is not performed.

Therefore, in the conventional video-on-demand system, real-time video cannot be provided since the video content being reproduced cannot be updated and registered at any time.

[0007] The present invention has been made in view of the above circumstances, and provides a video-on-demand system capable of preventing interference between a registration update request and a reproduction request for video content and providing a real-time video. With the goal.

[0008]

In order to achieve the above object, a video-on-demand system according to a first aspect of the present invention is a video-on-demand system which stores a video file consisting of video information divided into four or more blocks. Storage means; update block designating means for sequentially and cyclically designating update blocks to be updated among the blocks of the video file stored in the video storage means in a predetermined order; Playback block designating means for designating blocks other than the update block designated by the update block designating means among the blocks of the video file as playback blocks to be played; blocks of the video file stored in the video storage means Updating the video information by accessing the update block designated by the update block designating means. A lock updating unit; and a block reproducing unit that accesses a reproduction block specified by the reproduction block specifying unit among blocks of the video file stored in the video storage unit and reproduces video information. Features.

In order to achieve the above object, a second aspect of the present invention is provided.
The video on demand system according to the aspect of the present invention comprises: a video storage unit for storing a video file logically divided into four or more blocks; and an update block to be updated among the blocks stored in the video storage unit. Update block designating means for designating cyclically in a predetermined order,
Playback block designation means for designating blocks other than the update block designated by the update block designation means among the blocks stored in the video accumulation means as playback blocks to be reproduced, Block updating means for accessing the update block designated by the update block designation means of the updated blocks to update the video information, and designated by the reproduction block designation means of the blocks stored in the video storage means. And a block reproducing unit for reproducing the video information by accessing the reproduced block.

[0010] The playback block designating means may include means for designating a playback block based on the latest block that has been updated last among blocks that can be designated as the playback block.

[0011] The reproduction block designating means may include means for designating a reproduction block with at least one block interposed between the update block designated by the update block designating means.

[0012] The reproduction block designating means may include means for suppressing designation of at least one block adjacent to the update block designated by the update block designating means as a reproduction block.

[0013] The update block designating means, when at least one block adjacent to the designated update block is accessed by the block reproducing means,
A means for forcibly releasing access to the block by the block reproducing means may be further provided.

[0014] The block reproducing means may include a buffer means for temporarily storing the video information extracted from the reproduction block designated by the reproduction block designating means and providing it for reproduction.

[0015] A video-on-demand system according to a third aspect of the present invention comprises: a video storage means for storing a video file consisting of video information divided into four or more blocks; and a video stored in the video storage means. Update block designating means for sequentially and cyclically designating update blocks to be updated among the blocks of the file in a predetermined order; and the update block designating means among the blocks of the video file stored in the video storage means. A reproduction block designating unit that designates one or more blocks other than the designated update block as a reproducible reproducible block; and the update block designating unit among the blocks of the video file stored in the video storage unit. A block updating means for accessing a designated update block to update video information; Characterized by comprising the block reproduction means for reproducing video information by accessing renewable block the specified by the reproduction block specifying means of the blocks of the image file stored in the means.

A video-on-demand system according to a fourth aspect of the present invention is a video-on-demand system which is logically divided into four or more blocks, stores video files, and stores the video files in the video storage units. Update block designating means for designating update blocks to be updated in a predetermined order; and at least one of blocks stored in the video storage means other than the update block designated by the update block designating means. A reproduction block designating unit for designating a block as a reproducible reproducible block, and updating the video information by accessing the update block designated by the update block designating unit among the blocks stored in the video storage unit. A block updating unit, and a block designated by the playback block designation unit among the blocks stored in the video storage unit. Accessing renewable block, characterized by comprising, a block reproduction means for reproducing video information.

[0017] The reproduction block designating means may include means for designating a reproducible block based on the latest updated latest block among blocks reproducible as the reproducible block.

[0018] The reproduction block designating means may include means for designating a reproducible block with at least one block interposed between the update block designated by the update block designating means.

[0019] The reproduction block designating means may include means for suppressing designation of at least one block adjacent to the update block designated by the update block designating means as a reproducible block.

[0020] The update block designating means, when at least one block adjacent to the designated update block is accessed by the block reproducing means,
A means for forcibly releasing access to the block by the block reproducing means may be further provided.

[0021] The block reproducing means may include a buffer means for temporarily storing the video information extracted from the reproducible block designated by the reproducing block designating means and providing it for reproduction.

In the video-on-demand system according to the present invention, a video file composed of video information is divided into four or more blocks and stored, and the update blocks to be updated among the blocks of the video file are arranged in a predetermined order. To sequentially update the video information by accessing the designated update block and updating the video information, and designating blocks other than the update block as playback blocks to be played back and accessing the designated playback block. Play video information. In this system, a video file is divided into a large number of blocks, and access to registration and playback of video data is appropriately scheduled for each block, thereby preventing interference between a registration update request and a playback request for video content. And real-time video can be provided.

Software and programs for realizing the above-described video-on-demand system may be stored and distributed on a magnetic storage medium or an optical storage medium, or may be distributed and distributed via a communication medium or the like.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. A video-on-demand system according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 schematically shows a configuration of a video-on-demand system according to a first embodiment of the present invention. MP as video data to provide video content
An example in which video data compressed in the EG format is used will be described.

The video-on-demand system shown in FIG. 1 comprises a video camera 1, a video registration server 2, a VOD server 3, and a client PC (personal computer) 4.
A, 4B,..., 4X.

[0027] The video camera 1 is a video information source that shoots video and outputs video information. The video camera 1 is installed at a remote place, for example, and collects video contents such as real-time video. The video camera 1 may be a camera for obtaining video content that requires promptness such as news, or a camera fixed for fixed point observation such as a sightseeing spot video live broadcast system. Good. In this case, the video registration server 2 encodes the video data of the video information shot by the video camera 1 in real time in the MPEG format, compresses the data, and transmits it to the VOD server 3 via the high-speed communication line.

The VOD server 3 accumulates and stores the video data supplied from the video registration server 2, and transmits the stored video data to the client PCs 4A to 4X in response to requests from the client PCs 4A to 4X. Transfer to 4X.

The client PCs 4A to 4X are client terminals connected as terminals to the VOD server 3 via a communication line. These client PCs 4A-4X
Requests the VOD server 3 for a service of desired video information according to the operation of the user, decodes the video data in the MPEG format transferred from the VOD server 3 in response to the request, and displays the video content. . VO
A plurality of client PCs 4A to 4X are connected to the D server 3. The client terminal does not need to be constituted by a PC, but can be constituted by an apparatus having an arbitrary data processing function such as an office computer, a minicomputer, and a workstation. However, in this embodiment, a case in which the apparatus is constituted by a PC will be described as an example.

The VOD server 3 has a video data storage 5,
An update block management unit 6 and a reproduction block management unit 7 are provided. The video data storage unit 5 is configured by a large-capacity disk storage device such as a hard disk device, and stores video data of various video contents to construct a video database. In this case, each piece of video data is divided into at least four or more blocks, for example, a plurality of files, and stored in the video data storage unit 5 (in other words, the video data storage unit 5 is logically 4
The image data is divided into a plurality of blocks, and video data is stored in each of the blocks.)

The update block management unit 6 manages registration and update of video data from the video registration server 2 to the video data storage unit 5. That is, the registration of new video data in the video data storage unit 5 and the update of the already registered video data to the latest data are managed by the update block management unit 6 and are performed for each file on a block basis.

The reproduction block management unit 7 manages access to video data stored in the video data storage unit 5. The video data stored in the video data storage unit 5 is accessed and read under the control of the reproduction block management unit 7 in response to a request from the client PCs 4A to 4X, and is read out. 4X for playback. At this time, the reproduction block management unit 7
Manages the access to the video data stored in the video data storage unit 5 so as to be performed for each block in file units.

In this case, the update block management unit 6 registers new video data in the video data storage unit 5 and updates the already registered video data to the latest data for a plurality of divided files in a predetermined manner. Cyclically in the following order. When accessing the video data stored in the video data storage unit 5 at the request of the client PCs 4A to 4X, the reproduction block management unit 7
An access is made so as not to collide with a file updated by the video registration server 2 according to the update block management unit 6. The scheduling of access to the video data storage unit 5 by the update block management unit 6 and the reproduction block management unit 7 is a major feature of the present invention.

FIG. 2 shows a video data storage unit 5, an update block management unit 6, and a reproduction block management unit 7 of the VOD server 3.
3 schematically shows a functional configuration corresponding to the operation of FIG. FIG.
As shown in the figure, the video data stored in the video data storage unit 5 is divided into four blocks F1, F2, F3, and F4 which are continuous in time series, and is filed. The update block management section 6 has an update pointer 61, and the reproduction block management section 7 has a reproduction pointer 71.

The update pointer 61 specifies a file to be registered and updated by the video registration server 2. Here, the files F1 to F4 are sequentially and cyclically specified. The reproduction pointer 71 designates a file almost immediately after registration and update by the video registration server 2, accesses a file of almost latest video data, and provides the file for reproduction by the client PCs 4A to 4X. However, a file whose registration is being updated cannot be accessed until the update is completed, and the file to be updated must have completed access for reproduction at the time the update is started.

Therefore, the video data is stored in files F1 to F4.
Is divided into four parts, for example, the reproduction pointer 71
Specifies a file other than the file immediately adjacent to the file being updated based on the update pointer 61 among the files F1 to F4. That is, the file specified by the playback pointer 71 is not the latest file immediately after the update, but the next newest file. The file specified by the playback pointer 71 is not the file to be updated next to the file currently being updated, but the file to be updated next (1
Next file) For example, file F1
Assuming that the update pointer 61 designates the file F3 among the files F4 to F4 and the file F3 is currently being updated, the reproduction pointer 71 designates the file F1 excluding the files F2 and F4 adjacent to the file F3.

Next, a specific operation of the video-on-demand system configured as shown in FIGS. 1 and 2 will be described.
This will be described with reference to FIGS. For example, a real-time video taken by a video camera 1 installed at a remote place is real-time encoded into an MPEG format by a video registration server 2 in this case. Note that the real-time encoding into the MPEG format may be performed by the video camera 1 instead of the video registration server 2. The real-time encoded video data in the MPEG format is transferred from the video registration server 2 to the VOD server 3 as needed via a high-speed communication line such as a high-speed communication network, and the video data stored in the video data storage unit 5 is updated. It is performed sequentially. VOD server 3
The video data in the video data storage unit 5 is divided into a plurality of blocks and stored as a file of each block. The update of the video data in the video data storage unit 5 is cyclically performed by the update block management unit 6 in a predetermined order in a time series for each block file. In this way, the video data is constantly updated in the video-on-demand system.

The VOD server 3 reads out the video data stored in the video data storage unit 5 in response to a reproduction request from the client PCs 4A to 4X serving as client terminals, and transfers the read video data to the client PCs 4A to 4X. Always real-time video close to client P
C4A to 4X can be reproduced. The reading of the video data from the video data storage unit 5 is also performed by the reproduction block management unit 7 for each block file and so as not to conflict with the update of the video data by the update block management unit 6. Thus, the provision of the video data in the video-on-demand system is performed.

The video-on-demand system according to the present invention is largely characterized by the update of registration of video data from the video registration server 2 to the VOD server 3 and the scheduling of designation of video data read from the client PCs 4A to 4X. Hereinafter, registration and update of the video data from the video registration server 2 to the VOD server 3 and the client PC 4A
The specification of the read video data from .about.4X will be described in detail. The method of registering and updating a block file of video data in the VOD server 3 and the method of specifying a block file to be reproduced can be modeled as a ring buffer as shown in FIG.

The video data is divided into four blocks of files F1 to F4 and stored in the video data storage unit 5. The update processing of the video content is performed on the block file specified by the update pointer 61 of the update block management unit 6. The playback of the video content is performed on the block file specified by the playback pointer 71 of the playback block management unit 7.

The update file and the file to be reproduced in the video data storage unit 5 are scheduled by the update pointer 61 and the reproduction pointer 71 as shown in FIGS. It can be done without. Access to the video data registration update destination file and playback source file,
The scheduling method described above is called a ring buffer method.

In FIG. 3, the updating process of the video content is performed on the file F3, and the reproduction of the video content is designated by the file F1. That is, in FIG. 3, while updating the file F3,
Play 1 Then, when the file F3 is updated and the file F1 is reproduced, the file F4 is designated as the next update source and the file F2 is designated as the next reproduction source.

Then, the state shown in FIG. 4 is reached, and the file F4 is updated and the file F2 is reproduced. When the file F4 is updated and the file F2 is reproduced, the file F1 is designated as the next update source and the file F3 is designated as the next reproduction source.

Similarly, next, the state shown in FIG. 5 is reached. The file F1 is updated and the file F3 is reproduced. Then, the file F1 is updated and the file F1 is updated.
When the reproduction of No. 3 is performed, the file F2 is designated as the next update source and the file F4 is designated as the next reproduction source.

The same operation is sequentially repeated cyclically, and scheduling of the updated reproduction file by the ring buffer system is performed. As described above, in this scheduling, as shown in FIG. 2, the video data storage unit 5 stores the video data by dividing the file into four or more blocks of files, and specifies the file to be registered and updated. This is realized by using an update pointer 61 to be reproduced and a reproduction pointer 71 for specifying a file to start reproduction.

The update pointer 61 has, for example, an update pointer table.
A file to be updated for each piece of video information may be sequentially registered. The playback pointer 71 has, for example, a playback pointer table.
The latest reproducible file for each video information may be sequentially registered. In this way, the video data storage unit 5 having a small storage capacity such as a disk capacity can effectively provide real-time video.

For example, in a method of simply sequentially adding video information such as a live video from a video camera installed in a remote place to a disk area and selectively reproducing it,
Requires a lot of disk space. Therefore, FIGS.
In the system described above, the content of the file is updated as needed in the same disk area using the ring buffer method, thereby reducing the disk capacity required for storing real-time video.

Further, the following points are improved by such a ring buffer system. Conventionally, it has not been possible to update the contents of a video file being accessed for reproduction by a client terminal, that is, the client PCs 4A to 4X, by additional registration. In contrast,
With the above-described ring buffer method, it is possible to prevent the file to be updated from being played back, and it is possible to avoid updating the video file being played back.

The reproduction source file is a file that has been updated immediately before the file that has just been updated at that time. For this reason, almost the latest video can be reproduced from those registered in advance in accordance with the status of registration of video information in the VOD server 3 without performing special processing on the client PCs 4A to 4X side. .

The contents of the video file being updated cannot be reproduced until the registration is completed. So, VO
By subdividing the file size of the video information to be registered in the D server 3 into blocks, the additional update registration of each file of the live video to the VOD server 3 can be completed in a short time. Then, by sequentially reproducing the file immediately after the additional recording, it is possible to reproduce in almost real time at a timing very close to the input point.

As described above, when the video file is subdivided into a large number of blocks, the VOD server can reproduce the video for each area where the video camera 1 is installed, for example, in the case of a live video of fixed point observation. It is desirable to have a live video pointer table to the block of the latest video in the playback pointer. In this way, when a request to play a live video of a certain area is issued, the client P
Even if the C side is not aware of anything or the client P
When there is no special instruction from the C side, the live video pointer table is referred to, and the latest live video in the area is reproduced.

Further, in the video on demand service, special reproduction such as pause, slow reproduction, fast forward reproduction, rewind reproduction, and skipping to a desired portion is possible. In the ring buffer system described above, it is possible to cope with such special reproduction by subdividing a video file into a large number of blocks. However, pause, slow playback, fast forward playback using past video,
In order to realize special playback such as rewind playback and skipping to a past video, some contrivance is required. Therefore, the video-on-demand system according to the second embodiment of the present invention is a system that takes the above points into consideration.

FIG. 6 schematically shows a functional configuration corresponding to the operation of the VOD server of the video-on-demand system according to the second embodiment of the present invention.

As shown in FIG. 6, the video data storage section 5A
Are divided into ten blocks B1, B2,..., B10 which are continuous in time series, and are filed. Update block management unit 6A
Has an update pointer 61A, and
A has a reproduction pointer 71A.

The update pointer 61A indicates that the video registration server 2
Specifies the file to be registered and updated. Here, blocks B1 to B10 are sequentially and cyclically specified. The reproduction pointer 71A designates a block from almost immediately after registration update by the video registration server 2 to almost immediately before registration update. Playback block management unit 7A
Accesses the most recent block of video data based on the reproduction pointer 71A and
A to 4X for reproduction.

However, of the blocks B1 to B10, the block whose registration is being updated cannot be accessed until the update is completed, and the block to be updated does not have access for reproduction at the time of starting the update. Have to do it.

Therefore, the video data is stored in blocks B1 to B1.
If the playback pointer 7 is divided into ten, the playback pointer 7
1A is an update pointer 6 among the blocks B1 to B10.
A block other than a block immediately adjacent to the block being updated can be designated based on 1A. That is, the latest block that can be designated by the reproduction pointer 71A is not the latest block immediately after the update, but the next newest block as the latest block.
This latest block is a block for reproducing the live video and serves as a reference for specifying the reproduction pointer 71A. The oldest block that can be designated by the reproduction pointer 71A is not the block to be updated next to the block currently being updated, but the block to be updated next (one block from the block currently being updated). Next block)
It is. The playback pointer 71A can specify a block between these blocks to perform live video playback and various special playbacks.

For example, if the update pointer 61A designates the block B2 among the blocks B1 to B10 and it is currently being updated, the block B1 adjacent to the block B2 is updated.
One of the blocks B4 to B10 excluding the blocks B4 and B3 is designated by the reproduction pointer 71.

Next, a specific operation of the video-on-demand system as shown in FIG. 6 will be described with reference to FIG. As shown in FIG. 6, by increasing the number of blocks constituting the ring buffer from four in FIG. 2 to, for example, ten, the number of reproducible files can be increased as shown in FIG.

That is, in the case of FIG. 7, the video data storage 5A
Stores blocks B1 to B10 obtained by dividing video data. Update pointer 61 of update block management unit 6A
In accordance with A, the video registration server 2
2 (indicated by a rectangle in FIG. 7), the block B1 that has just been updated is the latest block. In this case, to avoid collisions,
The reproduction of the blocks B1 and B3 before and after the block B2 being updated is prohibited.

Accordingly, in the playback pointer 71A of the playback block management unit 7A, the blocks B4 to B10 (shown by circles in FIG. 7) are
It is possible to specify a playback block for playback in A to 4X. That is, by controlling the playback pointer 71A within the range using the reproducible block, special controls such as pause, slow playback, fast-forward playback using the past video, rewind playback, and skip to the past video are performed. Playback can be performed. in this way,
Increasing the number of divided blocks of video data stored in the video data storage unit 5A increases the number of reproducible blocks. Within these reproducible blocks, special reproductions such as slow reproduction, pause, rewind, etc., which go back to the past video, can be performed.

In a situation in which special playback such as slow playback, pause, rewind, etc. cannot be performed from the terminal, that is, the client PC side, the update destination block is obtained by the method described with reference to FIGS. Can always create a state where there is no reproduction access. However, as described above with reference to FIGS. 6 and 7, in order to ensure that there is no user trying to reproduce the video of the block to be updated by enabling special reproduction, the following two methods are required. The situation needs to be considered. (a) The video playback catches up with the block being updated. (b) The update catches up with the block being played.

The third embodiment of the present invention considers these situations and firstly prevents the video reproduction from catching up with the block being updated.

FIG. 8 schematically shows a functional configuration corresponding to the operation of the VOD server of the video-on-demand system according to the third embodiment of the present invention. As shown in FIG. 8, the video data stored in the video data storage unit 5B is equally divided into eight equal-sized blocks B1, B2,. The update block management unit 6B has an update pointer 61B,
The playback block management unit 7B has a playback enable pointer 72 and a pointer control unit 73.

The update pointer 61B is stored in the video registration server 2
Designates a file to be registered and updated. Here, blocks B1 to B8 are sequentially and cyclically designated. The reproducible pointer 72 has a pointer table for reproducible blocks, and only the blocks registered in the reproducible pointer 72 are the client PCs 4A to 4C.
It is possible to access it for playback by 4X. The pointer control unit 73 includes the reproducible pointer 72
And the block registered in the reproducible pointer 72 always has at least one free block with respect to the block registered and updated by the video registration server 2 almost immediately after the registration update. Specify the block from to just before the registration update.

In this case, the following two conditions are always ensured to prevent the video reproduction from reaching the block being updated. (1) The sizes of the blocks B1 to B8 of the video data are equal to each other. (2) There is always one or more free blocks between the reproducible block and the block being updated.

Therefore, the video data is stored in blocks B1 to B8.
Is divided into eight, for example, the pointer control unit 73
Pointer 72 controlled by block B
Of the blocks 1 to B8, one or more blocks, for example, one block immediately adjacent to the block being updated are designated based on the update pointer 61B. That is, the latest block designated by the reproducible pointer 72 is not the latest block immediately after the update, but the next newest block as the latest block. The oldest block that can be designated by the playable pointer 72 is
Not the next block to update after the one currently being updated,
Further, it is a block to be updated next (the next block which is set one after the block currently being updated).

When performing various special reproductions, the reproduction block management section 7B can access only the block designated by the reproducible pointer 72, and cannot reproduce other blocks. For example, block B1
If the update pointer 61A designates the block B2 among the blocks B4 to B8 and the block B2 is currently being updated, the blocks B4 to B8 excluding the blocks B1 and B3 adjacent to the block B2
Is designated by the reproducible pointer 72.

Next, a specific operation of the video-on-demand system as shown in FIG. 8 will be described with reference to FIG. As shown in FIG. 8, by controlling the block designated by the reproducible pointer 72 by the pointer control unit 73 so as to secure the above-described condition, the video reproduction reaches the block being updated. To prevent that.

That is, in the case of FIG. 9, the video data storage section 5B
Stores blocks B1 to B8 obtained by equally dividing video data. Update pointer 61 of update block management unit 6B
According to B, the video registration server 2
When the block 2 is updated, the block B1 whose update has been completed immediately before is the latest block. In this case, in order to avoid a collision, the reproduction of the blocks B1 and B3 before and after the block B2 being updated is prohibited by the pointer control unit 73.

In the reproducible pointer 72 of the reproduction block management section 7B, the blocks B4 to B8 are designated as blocks that can be used as reproduction blocks for reproduction by the client PCs 4A to 4X. That is, during special playback such as pause, slow playback, fast-forward playback using the past video, rewind playback, and skipping to the past video, only the block specified by the playable pointer 72 can be played. Become.

As described above, the blocks B1 to B8 obtained by equally dividing the video data are stored in the video data storage unit 5B, and the reproducible pointer 72 is controlled by the pointer control unit 73, so that the size of the blocks B1 to B8 of the video data is Are equal to each other, and the condition that there is always one or more empty blocks between the reproducible block and the block being updated is ensured. Therefore, even when performing special playback that goes back to the past video, such as slow playback, pause, and rewind, the playback block can be prevented from reaching the block being updated.

Next, consideration will be given to preventing the update from catching up with the block being reproduced.
It is conceivable that reproduction access such as pause or slow reproduction among special reproductions may cause a reproduction access to remain in the update destination block to be updated. In other words, the playback block may be stagnated by the playback such as the pause or the slow playback, and the update destination block sequentially advanced in real time may overlap the block that is still being played.

In such a case, the following two methods are used.
The access of the client PC (client terminal) accessing the block to be updated can be released. (ba) Forcibly disconnect playback access from the VOD server side. (bb) The terminal (PC) voluntarily cancels the pause or slow playback. Thus, in the fourth embodiment of the present invention, the VOD server forcibly cuts off the reproduction access so that the update does not catch up with the block being reproduced.

FIG. 10 schematically shows a functional configuration corresponding to the operation of the VOD server of the video-on-demand system according to the fourth embodiment of the present invention. In FIG. 10, video data stored in the video data storage unit 5B includes blocks B1 to B
8 are equally divided into eight equally sized blocks. As shown in FIG. 10, the update block management unit 6C
The reproduction block management unit 7C includes an update pointer 61B and an access check unit 62.
And an access control unit 74.

The update pointer 61B is stored in the video registration server 2
Designates a file to be registered and updated. Here, blocks B1 to B8 are sequentially and cyclically designated. The access check unit 62 instructs the access control unit 74 of the reproduction block management unit 7C whether or not there is a reproduction access immediately before the update access for the block specified by the update pointer 61B.

The reproducible pointer 72 has a pointer table for reproducible blocks, and only the blocks registered in the reproducible pointer 72
It is possible to access to provide for reproduction by C4A to 4X. The blocks registered in the reproducible pointer 72 always have one or more free blocks with respect to the blocks registered and updated by the video registration server 2 and are provided from almost immediately after the registration update to almost immediately before the registration update. Block is specified.

The access control unit 74 operates in association with the reproducible pointer 72 and accesses the client PC
It has an access management table for managing 4A to 4X.
As shown in FIG. 11, the access management table stores the terminal of the accessing user, that is, the client PCs 4A to 4X (more precisely, any of these) for each of the video blocks B1 to B8. I have. The access control unit 74 checks the presence / absence of reproduction access of the block to be updated next according to the instruction of the access check unit 62 of the update block management unit 6C, and if there is any of the client PCs 4A to 4X that are performing reproduction access. Then, the access of the client PCs 4A to 4X to the block is forcibly disconnected.

When the video data is divided into eight blocks B1 to B8, the reproducible pointer 72 is directly adjacent to one of the blocks B1 to B8 which is being updated based on the update pointer 61B. Specify 5 blocks excluding 2 blocks. For example, of the blocks B1 to B8, the block B2 is set to the update pointer 61B.
Is specified and is currently being updated, blocks B4 to B4 excluding blocks B1 and B3 adjacent to block B2
B8 is designated by the playable pointer 72.

Next, a specific operation of the video-on-demand system as shown in FIG. 10 will be described with reference to FIG. As shown in FIG.
The block specified by
And, the control by the access control unit 74 prevents the update of the video from overlapping the block being reproduced.

That is, in FIG. 10, an access control table (FIG. 11) for managing the client PCs 4A to 4X that are performing reproduction access for each block is prepared in the access control unit 74 of the reproduction block management unit 7C. Then, according to the update pointer 61B of the update block management unit 6C, the access check unit 62 causes the access control unit 74 to execute a check sequence for releasing access before starting registration update for the update destination block. According to the operation of the access control unit 74, if there is an access being reproduced based on the access management table, the access is forcibly disconnected.

For example, as shown in FIGS. 11 and 12,
Block B3 is reproduced by the client PC 4E,
Block B4 is reproduced by the client PC 4D,
Block B6 is reproduced by the client PC 4C,
It is assumed that block B8 is reproduced by the client PCs 4A and 4B. Now, update pointer 61
If the block B2 is being updated in accordance with B, the block B3 is updated next, so that the access check unit 62 operates a check sequence for the block B3. In this case, since the block B3 is being accessed by the client PC 4E, the reproduction access by the client PC 4E is forcibly disconnected.

As described above, the access control unit 74 prepares the access management table for managing the client PC performing the reproduction access for each block, and before starting the registration update for the update destination block, the access check unit 62. However, the access control unit 74 operates a check sequence for releasing the access, refers to the access management table, and forcibly disconnects the access if there is an access being reproduced. Therefore, even when the access state is stagnant due to slow playback or pause playback,
Forcibly canceling the reproduction of the block before the update block reaches the reproduction block can prevent the update block from overlapping the block being reproduced.

Next, in order to prevent the updated block from catching up with the block being reproduced and overlapping the two, the terminal (PC) voluntarily cancels the pause or slow reproduction from the terminal (PC) side. This is the fifth embodiment of the present invention. FIG. 13 schematically shows a functional configuration corresponding to the operation of the VOD server of the video-on-demand system according to the fifth embodiment of the present invention.

In FIG. 13, the video data storage unit 5B
Are equally divided into eight equal-sized blocks B1 to B8 that are continuous in time series, as in FIG. The update block management unit 6B
As in FIG. 8, it has an update pointer 61B. The update pointer 61B designates a file to be registered and updated by the video registration server 2, and sequentially designates blocks B1 to B8 sequentially.

In FIG. 13, the reproduction block management section 7D has a reproduction enable pointer 72 and an access control section 74A. The reproducible pointer 72 has a pointer table for reproducible blocks, and only the blocks registered in the reproducible pointer 72 can be accessed for reproduction by the client PCs 4A to 4X. The blocks registered in the reproducible pointer 72 always have one or more free blocks with respect to the blocks registered and updated by the video registration server 2 and are provided from almost immediately after the registration update to almost immediately before the registration update. Block is specified.

The access control section 74A operates in association with the reproducible pointer 72, and refers to the reproducible pointer 72 at predetermined time intervals at least when performing slow reproduction or pause reproduction. The time interval for referring to the reproducible pointer 72, that is, the predetermined time is set sufficiently short as compared with the time required for updating or reproducing one block. Then, when the reproduction access block deviates from the specification of the reproducible pointer 72, the access control unit 74A cancels the slow reproduction or the pause reproduction in the corresponding client PCs 4A to 4X.

As described above, the reproducible pointer 72
When the video data is divided into eight blocks B1 to B8, the update pointer 61 of the blocks B1 to B8
B that is immediately adjacent to one block being updated based on B
Specify five blocks excluding these blocks.

Next, a specific operation of the video-on-demand system as shown in FIG. 13 will be described with reference to FIGS. As shown in FIG. 13, at least during pause playback or slow playback, the access control unit 74
By A, the designated block of the reproducible pointer 72 is periodically checked. When the block being accessed for reproduction is out of the designated range of the reproducible pointer 72, the access control unit 74A determines that the corresponding client P
By forcibly canceling the pause reproduction or the slow reproduction of C and performing control so as to reproduce the normal live video, it is possible to prevent the update of the video from overlapping the block being reproduced.

That is, in FIG. 13, the access control unit 74A of the reproduction block management unit 7D is
When at least pause reproduction or slow reproduction is performed for A to 4X, the pointer table for the reproducible block of the reproducible pointer 72 is referred to at every preset time. When the block being played back by the client PCs 4A to 4X in the pause playback or the slow playback state deviates from the block registered in the pointer table to the reproducible block, the access control unit 74A sends the corresponding client PC 4A to 4X. Is released from the pause playback or the slow playback, and a normal, for example, live video playback is performed.

For example, as shown in FIG.
3 is played back in a pause playback state by the client PC 4A. If it is assumed that the block B2 is being updated according to the update pointer 61B, the block B3 is updated next, so that the block B3 is not a reproducible block. Therefore, the designation of the reproducible pointer 72 as a reproducible block is released, and registration of the reproducible block in the pointer table is deleted. The reproducible blocks at this time are blocks B4 to
B8.

The client PC 4A uses the block B
3 is reproduced in the pause reproduction state, the access control unit 74A refers to the reproducible pointer 72 at predetermined time intervals, and immediately when the designation of the reproducible block to the block B3 is released, Can be detected. Upon detecting the release of the designation of the reproducible block of the block B3, the access control unit 74A immediately releases the pause reproduction of the client PC 4A as shown in FIG. 15, and reproduces a normal live video after the block B4. .
Therefore, even when the access state is stagnant due to the slow reproduction or the pause reproduction, the pause reproduction or the slow reproduction of the block is forcibly released before the update block reaches the reproduction block, and the update block is reproduced. It is possible to prevent overlapping with the middle block.

Next, the processing when an update error occurs during updating will be discussed. Due to the occurrence of the update error, it is expected that video data of a specific block cannot be reproduced. In such a case, if the block is to be reproduced as it is, there is a danger that a system error or a hang-up will occur, causing inconvenience in subsequent reproduction or system operation. If the reproduction of the block is skipped, the reproduced video will be disturbed. In addition, there is a possibility that the timing for the block update may not be synchronized. So, at the time of reproduction,
For a block in which an update error has occurred, the effect of the update error can be minimized by reproducing a dummy video or blank video corresponding to the block size.

Therefore, when a block update error occurs, the effect of the update error is minimized by reproducing a dummy video or a blank video corresponding to the block size when a reproduction request is issued from the terminal. This is the sixth embodiment of the present invention.

FIG. 16 schematically shows a functional configuration corresponding to the operation of the VOD server of the video-on-demand system according to the sixth embodiment of the present invention. In FIG. 16, video data stored in the video data storage unit 5B includes blocks B1 to B
8 are equally divided into eight equally sized blocks. As shown in FIG. 16, the update block management unit 6D
The reproduction block management unit 7E includes an update pointer 61B and an update processing monitoring unit 63, and includes a reproducible pointer 72 and a reproduction control unit 75.

The update pointer 61B is stored in the video registration server 2
Designates a file to be registered and updated. Here, blocks B1 to B8 are sequentially and cyclically designated. The update process monitoring unit 63 monitors the update process for the update block specified by the update pointer 61B,
When the update fails and an update error occurs, for example, an update failure flag indicating an update failure is set in the video data of the block. This update failure flag is set as additional information in, for example, a header attached to the head of each block.

The reproducible pointer 72 has a pointer table for reproducible blocks, and only the blocks registered in the reproducible pointer 72
It is possible to access to provide for reproduction by C4A to 4X. The blocks registered in the reproducible pointer 72 always have one or more free blocks with respect to the blocks registered and updated by the video registration server 2 and are provided from almost immediately after the registration update to almost immediately before the registration update. Block is specified. The playback control unit 75 operates in association with the playable pointer 72, and detects an update failure flag of a playback block accessed for playback. When an update failure flag is detected during reproduction, the reproduction control unit 75 replaces the video data of the block with a prepared alternative video in the client PCs 4A to 4A.
Transfer to X for playback. As the substitute video, for example, appropriate dummy video data corresponding to a block size or blank video data corresponding to a block size can be used.

Next, a specific operation of the video-on-demand system as shown in FIG. 16 will be described with reference to FIG. As shown in FIG. 16, at the time of reproduction, the reproduction control unit 75 detects an update failure flag indicating an update error of a block, and reproduces a dummy video or a blank video corresponding to the block size. To a minimum. That is, in FIG. 16, when detecting the occurrence of an update error, the update process monitoring unit 63 sets an update failure flag in a corresponding block area among the blocks B1 to B8. At the time of reproduction at the request of the client PCs 4A to 4X, this update failure flag indicates the reproduction control unit 75.
Is detected by When detecting the update failure flag, the reproduction control unit 75 reproduces dummy video data such as a dummy video or a blank video prepared in advance instead of the data of the corresponding block area.

For example, as shown in FIG.
Assuming that a registration update error has occurred at the time of update of the block B2, the update processing monitoring unit 63 detects the error, and the block B2
, An update failure flag (indicated by an X in FIG. 17) is set. An update failure flag is set in the block B6 at the time of the previous update.

Assuming that the video after block B5 is being reproduced at the request of the client PC 4A, the reproduction control unit 75 detects an update failure flag in block B6. Upon detecting the update failure flag, the reproduction control unit 75 reproduces a dummy video or a blank video corresponding to the block size for the block, and performs subsequent reproduction.

As described above, the update process monitoring unit 63
Detect update errors, flag update failure,
At the time of reproduction, the reproduction control unit 75 reproduces a dummy or blank video for the block in which the update failure flag has been detected. Therefore, an adverse effect on reproduction due to the occurrence of an update error is minimized.

If the number of divisions of the video block is increased as described above, the time required for switching the video block during reproduction may not be ignored. Therefore, in this video-on-demand system, V
On the OD server 3 side and the client PC side, video continuity can be ensured as follows. VO
After the reproduction of one block of video is completed, the D server 3 starts sending the contents of the next video block without confirming the reception of the confirmation signal from the client PCs 4A to 4X.

In the client PCs 4A to 4X, a buffer for buffering video data for several seconds or more, for example, is provided in the client PCs 4A to 4X. VOD server 3 and client PCs 4A-4
In a transmission network between X, for example, 1.5 Mbp
If the bandwidth of s or more can be ensured, even if it takes some time to switch the pointer between the video blocks, the video stored in the buffer is played during that time.
Video continuity can be ensured.

Further, the blocks obtained by dividing the video data are set as smaller units on the disk, and the pointer operation is performed by an OS (operating system) for accessing the disk, that is, a disk operating system (DO).
By incorporating it in S), it is possible to achieve a VOD server that can reproduce even during registration of video data.

The video-on-demand system can be realized by using a general computer system without using a dedicated system. For example, a medium (a floppy disk, a floppy disk, or the like) storing a program for executing the above-described operation in a computer including a large-capacity auxiliary storage device storing image data and a relatively large-capacity buffer memory capable of dividing an area into four or more areas. By installing the program from a CD-ROM or the like, a video server of a video-on-demand system that executes the above-described processing can be configured.

Further, the medium for supplying the program to the computer may be a communication medium (a medium that temporarily and dynamically stores the program, such as a communication line, a communication network, or a communication system). For example, the program may be posted on a bulletin board (BBS) of a communication network and distributed via the network. Then, by starting this program and executing it in the same manner as other application programs under the control of the OS, the above-described processing can be executed.

[0107]

As described above, in the video-on-demand system according to the present invention, a video file consisting of video information is divided into four or more blocks and stored, and the update of the blocks of these video files is performed. A target update block is sequentially and cyclically specified in a predetermined order, and the specified update block is accessed to update the video information. A block other than the update block is specified as a reproduction block to be reproduced. The video information is reproduced by accessing the designated reproduction block. In this system, the video file is divided into a number of blocks, and the registration and playback access of video data is appropriately scheduled for each block so that the registration update request and the playback request do not interfere with each other.
It can provide almost real-time video and effective special playback video. That is, according to the present invention, video data registration and reproduction access is appropriately scheduled, thereby preventing interference between a video content registration update request and a reproduction request, and enabling video-on-demand provision of real-time video. A system can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of a video-on-demand system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a main part of the video-on-demand system in FIG. 1;

FIG. 3 is a schematic diagram of a first state for explaining an operation in the video-on-demand system of FIG. 1;

FIG. 4 is a schematic diagram of a second state for describing an operation in the video-on-demand system of FIG. 1;

FIG. 5 is a schematic diagram of a third state for describing an operation in the video-on-demand system of FIG. 1;

FIG. 6 is a block diagram showing a schematic configuration of a main part of a video-on-demand system according to a second embodiment of the present invention.

FIG. 7 is a schematic diagram for explaining an operation in the video-on-demand system in FIG. 6;

FIG. 8 is a block diagram showing a schematic configuration of a main part of a video-on-demand system according to a third embodiment of the present invention.

FIG. 9 is a schematic diagram for explaining an operation in the video-on-demand system in FIG. 8;

FIG. 10 is a block diagram showing a schematic configuration of a main part of a video-on-demand system according to a fourth embodiment of the present invention.

FIG. 11 is a schematic diagram for explaining an access management table in the video-on-demand system in FIG.

FIG. 12 is a schematic diagram for explaining an operation in the video-on-demand system in FIG. 10;

FIG. 13 is a block diagram showing a schematic configuration of a main part of a video-on-demand system according to a fifth embodiment of the present invention.

FIG. 14 is a schematic diagram of a first state for describing an operation in the video-on-demand system in FIG. 13;

FIG. 15 is a schematic diagram of a second state for describing an operation in the video-on-demand system of FIG. 13;

FIG. 16 is a block diagram showing a schematic configuration of a main part of a video-on-demand system according to a sixth embodiment of the present invention.

FIG. 17 is a schematic diagram for explaining an operation in the video-on-demand system in FIG. 16;

[Explanation of symbols]

Reference Signs List 1 video camera 2 video registration server 3 VOD (video on demand) server 4A to 4X client PC (personal computer) 5, 5A, 5B video data storage unit 6, 6A, 6B, 6C, 6D update block management unit 7, 7A, 7B, 7C, 7D, 7E Reproduction block management unit 61, 61A, 61B Update pointer 62 Access check unit 63 Update processing monitoring unit 71, 71A Reproduction pointer 72 Reproducible pointer 73 Pointer control unit 74, 74A Access control unit 75 Reproduction control unit

Claims (14)

[Claims] 1. A video storage means for dividing a video file into four or more blocks and storing the same, and updating blocks to be updated among blocks of the video file stored in the video storage means in a predetermined order. An update block designating means for cyclically designating, and a block other than the update block designated by the update block designating means among the blocks of the video file stored in the video storage means is designated as a reproduction block to be reproduced. Block updating means for accessing the update block designated by the update block designating means among the blocks of the video file stored in the video accumulating means to update the video information; and Of the blocks of the video file stored in the means specified by the playback block specifying means. A video playback system comprising: a block playback unit that accesses a raw block and plays back video information. 2. A video storage means for storing a video file logically divided into four or more blocks, and an update block to be updated among the blocks stored in the video storage means in a predetermined order. Update block designating means for cyclically designating, and a reproduction block for designating a block other than the update block designated by the update block designation means among blocks stored in the video storage means as a reproduction block to be reproduced. Designation means; block update means for accessing the update block designated by the update block designation means among the blocks stored in the video storage means to update the video information; and blocks stored in the video storage means Block that accesses the reproduction block designated by the reproduction block designation means and reproduces the video information. A video-on-demand system, comprising: 3. The reproduction block designating means includes means for designating a reproduction block on the basis of the latest block that has been updated last among blocks that can be designated as the reproduction block. 3. The video-on-demand system according to 1 or 2. 4. The reproduction block designating means includes means for designating a reproduction block by interposing at least one block between the reproduction block and the update block designated by the update block designation means. 4. The video-on-demand system according to 1, 2, or 3. 5. The reproduction block designating means according to claim 4, further comprising means for suppressing designation of at least one block adjacent to the update block designated by said update block designation means as a reproduction block. The video on demand system according to 1. 6. When at least one block adjacent to the designated update block is accessed by the block reproducing means, the update block designating means forcibly cancels access to the block by the block reproducing means. The video-on-demand system according to claim 4 or 5, further comprising means for causing the video-on-demand. 7. The apparatus according to claim 1, wherein said block reproducing means includes a buffer means for temporarily storing video information taken out from a reproduction block designated by said reproduction block designating means and providing it for reproduction. The video-on-demand system according to any one of the above. 8. A video storing means for dividing a video file into four or more blocks and storing the divided blocks, and updating blocks to be updated among blocks of the video file stored in the video storing means in a predetermined order. Update block designating means for designating, and one or more blocks other than the update block designated by the update block designating means among the blocks of the video file stored in the video storage means as reproducible reproducible blocks. Playback block designating means for designating; block updating means for updating video information by accessing an update block designated by the update block designating means among blocks of a video file stored in the video storage means; Playable specified by the playback block designating means among the blocks of the video file stored in the storage means And a block reproducing means for reproducing video information by accessing a functional block. 9. A video storage means for storing a video file logically divided into four or more blocks, and an update block to be updated among the blocks stored in the video storage means is arranged in a predetermined order. Update block designating means to be designated; and one of blocks stored in the video storage means other than the update block designated by the update block designating means.
Playback block designating means for designating at least one block as a reproducible reproducible block; and video information by accessing an update block designated by the update block designating means among blocks stored in the video storage means. And a block reproducing unit for reproducing video information by accessing a reproducible block designated by the reproduction block designating unit among blocks stored in the video accumulating unit. Video on demand system. 10. The reproduction block designating means includes means for designating a reproducible block based on a latest updated latest block among blocks reproducible as the reproducible block. The video-on-demand system according to claim 8. 11. The reproduction block specifying means includes means for specifying a reproducible block by interposing at least one block between the reproduction block and the update block specified by the update block specification means. Item 11. The video-on-demand system according to item 8, 9 or 10. 12. The reproduction block designating means includes means for suppressing designation of at least one block adjacent to the update block designated by the update block designation means as a reproducible block. 12. The video-on-demand system according to item 11. 13. When at least one block adjacent to the designated update block is accessed by the block reproducing means, the update block designating means forcibly cancels access to the block by the block reproducing means. 13. The video-on-demand system according to claim 11, further comprising means for causing the video-on-demand. 14. The apparatus according to claim 8, wherein said block reproducing means includes buffer means for temporarily storing video information extracted from the reproducible block designated by said reproducing block designating means and providing the information for reproduction. 14. The video-on-demand system according to any one of the thirteenth aspects.