JP2693367B2 - Video library system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video library system for simultaneously reading out a plurality of video programs from an information storage device such as a magnetic disk device, and a plurality of video programs for different terminals. It is used for the center equipment of the video-on-demand system provided at the same time.

[0002] In a video library system for simultaneously reading and providing a plurality of different video programs, even if the multiplicity is high, the start of a new request can be waited for without adversely affecting the reproduction of the currently ongoing video program. A technique is needed to minimize the time.

[0003]

2. Description of the Related Art As a conventional system of this type, for example, there is a "video library system" disclosed in Japanese Patent Laid-Open No. 4-269087. FIG. 4 is a block diagram of a conventional video library system, in which a disk device Dk21 which is an information storage device for storing video programs,
A plurality of buffer memories Bm2 via the switch Sw21
1, Bm22, Bm23, Bm24 are connected,
They are all controlled by the controller Cn21. Each buffer memory is Bm21A / Bm21B, Bm22
A / Bm22B, Bm23A / Bm23B, Bm24A
/ Bm24B has a two-sided structure of an A side and a B side. Monitors Tv21 and Tv in each buffer memory
22, Tv23, Tv24 are connected.

FIG. 5 is a time chart of multiple read control in the conventional video library system shown in FIG. In the figure, Ts21, Ts22, Ts23, Ts2
4 is a time slot, Pr2 is a time slot cycle time, Cts21 is a time slot sequence, and Rq21 and Rq2.
2, Rq23 and Rq24 represent time slot use requests for starting video program read (hereinafter referred to as video program read start request), and W22, W23 and W24 represent read start waiting times.

First, in the control unit Cn21, four time slots Ts21, Ts22, Ts23, Ts2 are provided.
A control time slot sequence Cts21 having a cycle of 4 is generated, and in response to a video program read start request from the outside,
The closest empty time slot is assigned, and thereafter the video program is continuously read out using the same fixed time slot. That is, as shown in FIG. 5, a video program read start request R to the monitor Tv21 at the beginning of the first cycle
A time slot Ts21 is assigned to q21. For the video program read start request Rq22 to the monitor Tv22 at the beginning of the second cycle, the time slot T
Since s21 is already in use, the next time slot Ts2
2 is allocated. Similarly, the monitor Tv2 at the beginning of the third cycle
The time slot Ts23 is allocated to the video program read start request Rq23 for the third time slot since the time slots Ts21 and Ts22 are already in use.
For the video program read start request Rq24 to the monitor Tv24 at the beginning of the cycle, the time slots Ts21, T
Since s22 and Ts23 are already in use, the time slot Ts24 is allocated. Then, in each time slot, the reading of the video program corresponding to each request of Rq21 to Rq24 is started.

Each time slot Ts21, Ts22, T
The video information read in s23 and Ts24 is
The buffer memory Bm is switched by the switch Sw21.
21, Bm22, Bm23, Bm24.
In each buffer memory, at first, side A (Bm21A, Bm21A, Bm21A,
22A, Bm23A, Bm24A) switch Sw21
The video information transferred from the device is temporarily stored, and immediately after the end of each time slot, the monitor information Tv21, Tv22, Tv23, Tv24 connected to each buffer memory is multiplied by one time slot cycle time Pr2 to display the video information. I do.

Thereafter, each monitor Tv21, Tv22, Tv
23 and Tv24 are continued, the same time slots Ts21, Ts22, Ts23, and T used to start the reading of the video program are continued.
Similarly, using s24, the video information is read, the transfer destination buffer memory is switched, and the transfer to the buffer memory is performed. Of the two faces of the buffer memory A and B, one face has already accumulated the video information for the current monitor display, so that the vacant face is accumulated. Each monitor Tv
In 21, Tv22, Tv23, and Tv24, when the current video information accumulated in the buffer memory surface is completed, the buffer information is switched to another buffer surface to continuously display the video information.
At this time, the same time slot always rotates in the same phase within one cycle, so that the display of the video program on each monitor can be continued without interruption.

[0008]

In the conventional video library system as described above, in response to a request to start reading a video program from a terminal, the empty time slot closest to the request time is used to read the video information. Start,
After that, the same time slot used at the beginning was used to read out the video information for continuous display of the video program. In this case, after issuing the video read start request, until the empty time slot comes around,
The reading of video information will be delayed.

For example, in FIG. 5, the waiting times for the video program read start requests Rq22, Rq23, and Rq24 are W22 (one time slot) and W23, respectively.
(For 2 time slots) and W24 (for 3 time slots). In this way, the waiting time from when a request is issued to when the first reading of the video program from the information storage device for that request is actually started has only one empty slot, and the request is empty. When it is issued immediately after the slot, it becomes the maximum, and the waiting time until it can be actually displayed matches the length of one cycle.

On the other hand, since the access time of the disk device is, for example, about 20 to 50 ms in the case of a magnetic hard disk device, a time slot of 50 m is required for implementation.
It is necessary to set the time slot to s or more, and further to set the time slot to 100 ms or more in order to improve the reading efficiency of the video information in one time slot. For example, if the time slot is set to 0.5 s, the waiting times of W22, W23, and W24 shown in FIG. 5 correspond to 0.5 s, 1 s, and 1.5 s, respectively. Further increase the number of time slots in one cycle,
When the number of multiplexing is increased, this waiting time increases. For example, when one cycle is 0.5 s and one cycle is 100 time slots, the maximum waiting time reaches 50 seconds.

An object of the present invention is to shorten the waiting time for starting the reading of a new video program without interrupting the reproduction of each video program that is currently continuing.

[0012]

In order to achieve the above object, the present invention switches between an information storage device storing a plurality of video programs and a transfer destination buffer memory of video information read from the information storage device. A switch, a controller for controlling the information storage device and the switch for each time slot in a periodic time slot sequence, a plurality of buffer memories for temporarily storing video information transferred from the switch, In a video library system having a plurality of monitors for displaying video information temporarily stored in the buffer memory, the time slot used for starting the reading of a video program has a high priority and the video currently being read is Timeslots used for program continuity are of low priority and require the use of timeslots Means for sequentially allocating time slots to be used on a first-come-first-served basis for each priority for each time slot use request, and time slot use for starting the reading of a new video program generated within one cycle time. And a means for limiting the number of requests generated to be equal to or less than the total number of empty time slots in the current one cycle.

The prior art differs greatly in that the used time slot for each video read request is not fixed but is dynamically assigned with priority.

[0014]

[Operation] A time slot used for starting the reading of a new video program has a high priority, and a time slot used for continuing the video program currently being read has a low priority, and the use of the time slot is requested. By means of this means, it becomes possible to identify the priority of the current time slot use request, and by means of sequentially allocating time slots to be used on a first-come-first-served basis for each time slot use request, a large number of times are currently available. Even if the other video programs are being read, the use of the time slot for starting the reading of the new video program is executed earlier than the use of the time slot for continuing the video program. Therefore, the waiting time from when a new video read request is received until the video information is actually read out is It is shrinking.

Further, by means of limiting the number of time slot use requests for starting the reading of a new video program occurring within one cycle within the total number of empty time slots within one cycle, The total number of time slots used with high priority for reading a video program is at most within the number of empty time slots within one cycle. Therefore, even if a time slot use request is issued with a low priority for continuation of a video program and the use is delayed due to a high priority use request, one cycle is always issued from the time when the request is issued. Within that it can be guaranteed that the time slot can be used. This enables continuous video playback for each ongoing video program.

[0016]

1 is a block diagram of an embodiment of the present invention. A disk device Dk11, which is an information storage device for storing video programs, is connected to a plurality of buffer memories Bm11, Bm12, Bm13, Bm14 via a switch Sw11, all of which are controlled by a control device Cn11. . Each buffer memory may be a FIFO memory, but here, Bm11A / Bm11B, Bm12A
/ Bm12B, Bm13A / Bm13B, Bm14A /
Like Bm14B, it has a two-sided structure of an A side and a B side. Each buffer memory Bm11, Bm12, Bm
Time slot use request devices Tr11, Tr12, Tr13, Tr14 are connected to 13 and Bm14, respectively. Furthermore, each buffer memory Bm11, Bm1
2, Bm13 and Bm14 have a monitor Tv1 respectively.
1, Tv12, Tv13, Tv14 are connected.

The control unit Cn11 is a time slot management unit Cn that dynamically manages the allocation of time slots.
12 is connected to the management device Cn12, and a time slot use request queue Cn of low priority is connected to the management device Cn12.
13 and the high priority time slot use request queue Cn14 are connected. The queue Cn13 includes the time slot use request devices Tr11, Tr12, T
It is connected to r13 and Tr14. On the other hand, queue C
n14 is connected to the control device Cn15 which controls the number of read start requests for new video programs from the outside. A request to start reading a new video program is issued to the control device Cn15.

A request R for starting the reading of a new video program from the outside to the monitor Tv11 to the controller Cn15.
The flow of processing when q11 arrives is shown in FIG. When the request Rq11 arrives (Ch0), first, the control device Cn
At 15, it is determined whether the number of video program start requests in the past one cycle time Pr1 exceeds the total number of empty time slots in the current one cycle (Ch1). If it exceeds the threshold, the request is made to wait for one time slot (Ch2), and the determination is made again (Ch1). If it does not exceed, the request Rq11 is input to the time slot use request queue Cn14 of high priority as a time slot use request for starting the video program reading (Ch3). The queue Cn14 is a first-come-first-served processing discipline, and time slots are allocated in order from the request at the head of the queue at each time slot head.

Next, it is judged whether or not the read start request Rq11 of the video program has reached the head of the queue Cn14 (Ch4), and if it has not reached, wait for one time slot (Ch5). . If the read start request Rq11 for the video program reaches the head of the queue Cn14 at the head of the time slot Ts11, the time slot management device C immediately starts.
n12 allocates the current time slot Ts11 to the request Rq11, and the controller Cn11
The disk device Dk11 and the switch Sw11 are set,
Disk device Dk1 using time slot Ts11
The video information for one cycle Pr read from 1 is transferred to the buffer memory Bm11A through the switch Sw11 (Ch6). Then, after the end of the time slot Ts11, display of the video information accumulated in the buffer memory Bm11A on the monitor Tv11 is started (Ch7).

Next, a disk device D for all video program information
It is judged whether the reading from k11 is completed (Ch
8) If it is finished, the process is finished (Ch
9). When the following video information exists in the disk device Dk11, the time slot use request device Tr11
As a result, the time slot use request Sq11 for continuing the video information currently being read to the currently empty buffer memory Bm11B is output to the time slot use request queue Cn13 of low priority (Ch10).

Next, it is judged whether or not the request Sq11 input to the queue Cn13 has reached the head of the queue Cn13 and the queue Cn14 having a high priority has no wait (Ch11). If this state has not been reached, waiting for one time slot is performed (Ch12). The number of time slot use requests input to the queue Cn13 for continuation of a video program at any given time is always less than or equal to the number of monitors currently performing continuous display of the video program. Since the queue Cn13 is a first-come-first-served processing discipline, the request is always issued within a time slot time corresponding to the number of monitors currently displaying the continuous video program from the time when a new request is input to the queue Cn13. Reach the top of the queue.

The number of time slot use requests input to the queue Cn14 in the last one cycle is determined by the control device Cn.
Since the number is limited to the total number of empty time slots within one cycle by 15, the queue Cn14 is within the time slot time of the total number of empty time slots within one cycle from the time when a new request is input to the queue Cn13. The request inside is empty. Since the sum of the "number of monitors requesting continuation" and the "total number of empty time slots" is the total number of time slots in the cycle, from the time of issuing the time slot use request Sq11, it must be within one cycle Pr1. The request Sq11 reaches the head of the queue Cn13,
Moreover, the queue Cn14 reaches a state where there is no waiting.

If the request Sq11 reaches the head of the queue Cn13 at the head of the time slot Ts12 and the queue Cn14 reaches a waiting state, the time slot management device Cn12 immediately responds to the request Sq11. Current time slot Ts12
Is allocated, the controller Cn11 sets the disk device Dk11 and the switch Sw11, and the video information for one period Pr1 read from the disk device Dk11 using the time slot Ts11 is switched to the switch Sw1.
1 to the buffer memory Bm11B (Ch
13).

Next, it is judged whether or not the display of the video information started at Ch7 in FIG. 2 is finished (Ch1).
4). If it has not ended, one time slot is waited for (Ch15). Time slot Ts
If the display of the video information is completed at the end of 12, the process returns to Ch7 of FIG. 2 again, and the continuous display of the video program is displayed on the monitor Tv11 using the buffer memory surface (Bm11B) in which the video information is accumulated. At the same time as the start, the request Sq11 is issued.

The above is the read start request R for each video program.
Regarding the processing flow for q11, an example of a time chart in the case where a read start request for a plurality of video programs is generated is shown in FIG. This figure shows four monitors Tv11 and Tv1.
2, an example in which read start requests Rq11, Rq12, Rq13, and Rq14 of a video program to Tv13 and Tv14 are generated. As indicated by ch10 in FIG. 2, after the start of reading the video program, the use request Sq1 of the time slot for continuation of the video program being read every time one of the buffer memories becomes empty in each buffer memory.
1, Sq12, Sq13, Sq14 are issued.

At the beginning of the time slot Ts12 of the second cycle, the video program read start request Rq12 and the time slot use request Sq11 for continuation of the video program being read overlap with each other. Since the time slots are assigned with priority, there is no waiting to start reading the video program. Further, at the beginning of the time slot Ts12 of the third cycle, a read start request Rq13 of the video program and a use request Sq of the time slot for continuation of the video program being read.
11, and at the beginning of Ts13 in the fourth cycle, the read start request Rq14 of the video program and the use requests Sq12 and Sq13 of the time slot for continuation of the video program being read are overlapped. Also, video program read start requests Rq13, Rq14
No priority has been given to the video program, so there is no waiting to start reading the video program.

As described above, the video program read start requests Rq11, Rq12, Rq13, and Rq14 have high priority, and time slot use requests Sq11, Sq12, Sq13, and Sq for continuing the video program being read.
Time slots are assigned to 14 with low priority. Therefore, at the start of reading a video program, reading of video information is started without waiting time. Further, regarding the time slot use requests Sq11, Sq12, Sq13, and Sq14 for continuing the video program being read, the read start request Rq1 of the video program having a high priority is also issued.
1, Rq12, Rq13, Rq14 are present, or when a time slot use request for continuing a video program has already been issued in advance, the time slot is delayed within 1 cycle after the request is issued. Has been assigned.

As described above, in the present embodiment, the display of the video program on all the monitors does not have to be waited at the start of reading the video program, and the video program can be continued without interruption.

[0029]

As described above, according to the present invention, the reading of a new video program is started while guaranteeing the use of the time slot for continuation of each video program currently being read within one cycle after the request. Since the priority control of the use of the time slot is performed, there is an effect that the waiting time for starting the reading of a new video program can be shortened without interrupting each video program that is currently continuing.

While reading one video program,
Even when starting special playback such as frame jump for playing the same video program from another time point, the video information from another time point after the jump is considered as a new video program, and the reading is started after the frame jump. The priority control of the time slot used for is also effective in shortening the jump response time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a processing flowchart for one video program read start request in the embodiment of the present invention.

FIG. 3 is a time chart when a plurality of video program read start requests are received in the embodiment of the present invention.

FIG. 4 is a block diagram of a conventional video library system.

FIG. 5 is a time chart of a conventional video library system.

[Explanation of symbols]

Dk11 Disk device Sw11 switch Bm11, Bm12, Bm13, Bm14 Buffer memory Bm11A / Bm11B to Bm11A / Bm11B
Buffer side Cn11 Control device Cn12 Time slot management device Cn13 Low priority time slot use request queue Cn14 High priority time slot use request queue Cn15 Control device Tr11, Tr12, Tr13, Tr14 Time slot use request device Tv11, Tv12 , Tv13, Tv14 monitor Ts11, Ts12, Ts13, Ts14 time slot Pr1 time slot cycle time Cts11 time slot sequence Rq11, Rq12, Rq13, Rq14 video program read start request Sq11, Sq12, Sq13, Sq14 for continuation of video program Time slot usage request

Claims (1)

(57) [Claims] 1. An information storage device in which a plurality of video programs are stored, and a plurality of monitors for displaying video information, wherein a request for a video program from the monitor is provided.
In a video library system for allocating a time slot in a periodic time slot sequence and controlling the reading of video information from the information storage device in the allocated time slot, in order to start the reading of a video program when the time slot is used Means for requesting the use of timeslots with a high priority for the timeslots used for, and low priority for the timeslots used for continuation of the video program currently being read, Means for sequentially allocating time slots on a first-come-first-served basis for each priority, prioritizing the higher priority ones in response to slot use requests, and a time slot for starting the reading of a new video program generated within one cycle time. The number of usage requests generated is determined by the available time slot within the current cycle. Video library system characterized by having a means for limiting the total number following.