JPH09102924A - Video data filing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency of data transfer from a storage device by performing the read-out scheduling of the storage device to a pseudo cyclic request signal. SOLUTION: In a slot managing device 5, a fixed cycle is set based on time information provided from a timer 8 and in each cycle, the read-out table of a magnetic disk storage device 8 is sent to a scheduler 6. When there is a slot allocation signal from a request converting device 4, according to this allocation signal, the managing device 5 changes the read-out table. Based on read-out conditions such as the position of video data on the disk, position and deadline described in respective reading requests contained in the read-out table, the scheduler 6 decides the order of reading from respective disks in the storage device 9 and prepares a schedule table. This table is sent out to a reading controller 7 and according to this schedule, reading from the storage device 9 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video data file device for continuously supplying video data to a plurality of user terminals, and more particularly, to a magnetic field for aperiodic video data transmission requests from the user terminals. The present invention relates to a video data file device that supplies data by periodically reading from a storage device such as a disk.

[0002]

2. Description of the Related Art In recent years, multi-channel type video information services using CATV, public lines, etc. have been spreading.
One of the services that is becoming mainstream among these services is that the user selects the video information such as a movie that he / she wants to watch through two-way communication between the user and the business, and the business searches for this video information. A service for selectively transmitting to a lever user, so-called video on demand (VOD:
VIDEO ON DEMAND). In order to perform such a service, a method is generally used in which a VCR device corresponding to a user who has requested a video service is prepared, and video information is reproduced by the VCR and transmitted to the user. However, this method requires the same number of VCR devices as the number of users requesting the service, and the same number of media (VCR tapes) as the number of users requesting the service for the same information. There are problems such as the necessity.

As a method of electronically solving such a problem, the image information is divided into a large number of segments, which are distributed and stored in a plurality of medium-speed storage devices (such as magnetic disks), and these are stored by the user. There is known a method of reproducing the original video information by sequentially reading and combining them in response to the request. With such a technique, the same or different video information can be simultaneously provided to a plurality of users by one set of reproducing apparatus. Hereinafter, the basic configuration of this technique will be described with reference to the drawings.

FIG. 6 is a diagram showing the basic configuration of the VOD system as described above. In the figure, a plurality of user terminals 100 are connected to the video server 110. The user terminal 100 decodes and reproduces packet-shaped data of a certain size supplied from the video server, and sequentially requests the video server to send successive video data packets so that the reproduced data is not interrupted. . The video server 100 includes a user control device 10
1, read queue 102, read control device 103,
It is composed of a magnetic disk storage device 104 and a data buffer 105. The user control device 101 integrates video data distribution requests from a plurality of user terminals 100,
Further, a request signal from each terminal is sent to the magnetic disk storage device 1
It is converted into position information on 04 and sent to the read queue 102. The read control device 103 uses the read queue 1
The read request packet is sequentially fetched from the control unit 02 to control the magnetic disk storage device 104 for reading.
The read data is temporarily stored in the data buffer 105, packetized into a form suitable for distribution to the user terminal 100, and then transmitted via the user control unit 101 to the user terminal 1.
Sent to 00.

In this way, the magnetic disk storage device 1
The data stored in 04 is sequentially transmitted to a plurality of user terminals 100, and continuous video reproduction is performed in each user terminal 100.

In such a structure, the video server 1
Assuming that the data rate that can be supplied from the magnetic disk storage device 10 is N times the average data rate that the user terminal 100 requests the video server 110, one video server can continuously connect up to N terminals. It becomes possible to supply video data. Further, in the magnetic disk storage device 104, if there are no restrictions on the reading position and the order, a maximum of N parallel readings of the same data (program) becomes possible.

[0007]

However, in the video data distribution according to the above configuration, the user terminal 1
If the video data packet does not reach the user terminal within a fixed time (usually determined by the size of the data buffer in the user terminal 100) after 00 makes a data packet request to the server 110, the reproduced video is interrupted. I will end up. For this reason, when many terminals are connected or when data request timing from multiple terminals concentrates in a very short period, it may not be possible to reproduce normal video on each terminal. .

On the other hand, in the above system, it is considered that the data packet request from each user terminal is randomly generated. Realistic design parameters for such user terminal model (read queue depth,
When the system is designed with the data buffer amount in the server and the terminal), the average read capability is 20 times that of the data read capability of the magnetic disk storage device 104 that limits the maximum data transfer rate of the server 110. ~ 3
It is known that it is necessary to set it to about 0%.
("Multiple Access Technology for Moving Image Information", Technical Report, Television Society, Vol. 16, No. 27, page 40) As described above, the storage device has a very low average data transfer rate as compared with the maximum data transfer capacity of the storage device. Had to be operated, and the use efficiency of the storage device was very poor.

The present invention has been made in order to solve such a problem, and converts a data packet request signal randomly generated by each terminal into a request signal having a high periodicity, and the pseudo periodic request is generated. The efficiency of data transfer from the storage device is improved by performing read-out scheduling of the storage device for signals.

[0010]

In order to solve the above-mentioned problems, a first video data file device according to the present invention includes a user control section for monitoring data requests from a plurality of user terminals, and a data storage section. Read control unit that schedules the order in which the video data to be supplied to the plurality of user terminals is read, and a read request is periodically issued to the read control unit according to the approximate data rate of the video data to be supplied to each of the user terminals. The slot management unit that outputs the data and the request conversion unit that controls the periodicity of the read request output in the slot management unit based on the frequency of data requests from each user terminal obtained from the user control unit The efficiency of reading video data from the storage unit is improved.

Further, the second video data file device of the present invention monitors the remaining amount of data corresponding to each terminal in the data buffer which temporarily stores the video data to be sent to each user terminal. A buffer monitoring unit, a user control unit that monitors data requests from a plurality of user terminals, a read control unit that schedules the order in which video data to be supplied from the data storage unit to the plurality of user terminals is scheduled, and a user control unit for each user terminal. A slot management unit that periodically outputs a read request to the read control unit according to the approximate data rate of the supplied video data, a frequency of data requests from each user terminal obtained from the user control unit, and a buffer monitoring unit Read request output in slot management unit based on the remaining amount of video data sent to each user terminal obtained from By configuring than the required conversion unit for controlling the periodicity, it is intended to improve the reading efficiency of the video data from the data storage unit. The continuous media data is managed by the attribute table described above.

Further, the third video data file device of the present invention is the first and second video data file devices, wherein the request conversion unit controls the number of read requests output from the slot management unit to the read control unit. Thus, the efficiency of reading the video data from the data storage unit is improved.

Further, according to the fourth video data file device of the present invention, the request conversion unit controls the data amount of the read request output from the slot management unit to the read control unit, thereby reading the video data from the data storage unit. It increases efficiency.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, according to the above-mentioned first configuration, the slot management section is provided to each of a plurality of user terminals without depending on the data packet request from the user terminal which the user control section actually receives. A read request is periodically output to the read control unit according to the approximate transmission data rate of the supplied video data. The request converter is
The difference between the frequency of data packet requests actually received by the user control unit and the periodic read request output by the slot management unit is detected to roughly change the transmission data rate to the slot management unit or perform temporary reading. Instruct to change the amount of data. With such a configuration, the slot management unit outputs a read request for data output to the read scheduler with a strong periodicity, which enables static and efficient storage device scheduling in the read scheduler. It can handle many read requests.

According to the second aspect of the present invention,
Similar to the first configuration, the slot management unit sets the approximate transmission data rate of the video data supplied to each of the plurality of user terminals, regardless of the data packet request from the user terminal that the user control unit actually receives. In response, the read request is periodically output to the read control unit. The request conversion unit detects the difference between the frequency of data packet requests actually received by the user control unit and the periodic read request output by the slot management unit, and determines whether the slot management unit changes the approximate transmission data rate. Instruct to temporarily change the amount of read data. Furthermore, by monitoring the remaining amount of data to be sent to the corresponding user terminal in the data buffer, the frequency of video data consumption and data request at the user terminal is predicted, and similarly, it is roughly estimated for the slot management unit. A temporary change in the outgoing data rate can be indicated. With such a configuration, the slot management unit can further increase the periodicity of the data read request output to the read scheduler, and the scheduling of the storage device in the read scheduler becomes easier.

Further, according to the third and fourth configurations of the present invention, the request converter controls the number of read requests output from the slot manager to the read controller, or controls the data amount of the read requests. Thus, it is possible to change the read rate of the video data from the data storage unit without making a drastic change in the scheduling procedure of the storage device in the read scheduler.

[0017]

【Example】

(Embodiment 1) Hereinafter, a video data file device of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a video data reproducing system according to the first embodiment of the present invention. In FIG. 1, a plurality of user terminals 2 are connected to the video server 1. The user terminal 2 decodes and reproduces packet-shaped data of a certain size supplied from the video server 1, and sequentially requests the video server 1 to send successive video data packets so that the reproduced data is not interrupted. ing. The video server 1 includes a user control device 3, a request conversion device 4, a slot management device 5, a read scheduler 6, a read control device 7, a timer 8, a magnetic disk storage device 9, a data buffer 10 and the like. The timer 8 provides time information to the slot management device 5 and the request conversion device 4.

When the user terminal 2 wants to receive the video data service from the video server 1, the request conversion device 4 and the slot management device 5 are prior to the start of the service.
Is set to the frequency at which the user terminal requests the video data packet. In the request conversion device 4, the difference (slot allocation signal) between the request frequency and the actually requested request signal is sent to the slot management device 5. Such a difference occurs due to the state of the communication path between the video server 1 and the user terminal 2, the temporary change of the video reproduction speed in the user terminal 1, and the like. The slot management device 5 sets a fixed cycle based on the time information obtained from the timer 8 and sends the read table of the magnetic disk storage device 9 to the scheduler 6 for each cycle. I read the table,
The read request to the magnetic disk storage device 9 corresponding to the data amount obtained by multiplying the average data rate set for each terminal by the cycle time is described. As described above, since the data rate required by each terminal is initially set in the slot management device 5 and the request conversion device 4, in the steady state, unless the data rate required by each terminal changes. , The slot management unit 5 sends the same read table to the scheduler 6.

When there is a slot allocation signal from the request conversion device 4, the slot management device 5 changes the read table according to this allocation signal. Scheduler 6
Is the position and size on the disc of the video data described in each read request included in this read table,
Based on the reading conditions such as deadline, determine the order of reading from each disk in the magnetic disk storage device,
Create a schedule table. This schedule table is sent to the read control device 9, where the read control of the magnetic disk storage device 9 is performed according to this schedule.

The data read from the magnetic disk storage device 9 is temporarily held in the data buffer 10, packetized in accordance with the packet request signal from each user terminal received by the request conversion device 4, and then the user control device 3 is processed. Is sent to the corresponding user terminal 1.

FIG. 2 shows the structure of a read table generated in the slot management device 5. In FIG. 1, the video server 1 is connected to nine user terminals 2, and the magnetic disk storage device 9 is composed of two disks A and B. When accepting a video reproduction request from a new user terminal, the slot management device 5 determines whether the new video reproduction request can be accepted from the read table calculated based on the average data rate requested by each user terminal. Predict. The packet request signal from each terminal is instructed to the slot management apparatus by the difference (correction value) from the request amount of the video data predicted from each average data rate in the request converter 4. FIG. 2 is a read table obtained by performing the above-described correction on the average amount of data required by each terminal. In the figure, each column is the number of the user terminal, the disk number where the data requested to be read is stored, the sector number, the track number, and the amount of data to be read. In this table, when the slot allocation signal from the request conversion device 4 is given, the slot management device adjusts the read data amount by increasing or decreasing the read data amount or by not assigning the read data.

The read table of FIG. 2 is the scheduler 6
And a schedule table for each disk as shown in FIG. 3 is created. In the table of the figure, the slots are sorted by the sector number of the disk. Therefore, the read control device 7 can optimize the disk access by the F scan algorithm by controlling the magnetic disk storage device 9 using this schedule table. All of the read requests written in the schedule table shown in FIG. 2 are read from the magnetic disk storage device 9 and stored in the data buffer within the above-described cycle cycle. In this table, the slot allocation signal from the request converter reflects the change in the amount of read data and the presence or absence of read slot allocation.

FIG. 4 is a diagram showing an operation chart of the video server 1. The video server 1 operates with a fixed cycle as represented by cycle 1 and cycle 2 in the figure as a repeating unit. In the figure, 20 to 22 are user terminals 4.
Shows the packet request operation from the request converter, the operation of the slot counter in the request converter 4 for the same terminal, and the slot allocation output from the request converter 4. Similarly, 23 to 25 are packet request operations from the user terminal 1. The operation of the slot counter in the request converter 4 for the same terminal and the slot allocation output from the request converter 4 are shown. The unit of packet request from the user terminal is 200 kB, and the reading and transfer of data in the video server 1 is also 200 kB.
Is performed in slot units. The slot counter is
This counter is a counter that decrements from this value by 1 each time a packet request occurs, with the number of slots per cycle corresponding to the average data rate set at the start of the session between the video server 1 and the user terminal 2 as an initial value. Is set to the initial value at the beginning of each cycle and becomes zero at the end of the cycle. If this value does not become zero, the request conversion device 4 issues an instruction to the slot management device 5 to increase or decrease the slot allocation or change the presence or absence of the slot allocation. In the figure, since the number of packet requests from the terminal 4 in the cycle 1 is smaller by 1, the request converter 4 reduces the slot management device 5 by 1 (200 kB in slot allocation) in the cycle 2. Since the number of packet requests from the terminal 1 in the cycle 2 is increased by 1, the request converter 4 instructs the slot management device 5 in the cycle 3 to increase "one slot allocation (200 kB)". Is instructed. The slot management device 5 generates a read table by integrating the instructions from the request conversion device 4 regarding such slot allocation, and the scheduler 6 receives the read table as an input.
Creates a schedule table.

As shown in FIG. 4, the read control device has a period 1d, 2d, 3 which is slightly delayed from the period 1, 2, 3.
It operates in d and accesses the two disks A and B according to the schedule table output by the scheduler 6. For example, cycle 1d
Then, the disks A and B are accessed in the order shown in the table of FIG. In the period 2d, the number of slots corresponding to the terminal 4 is reduced by 1, and in period 3d, the number of slots corresponding to the terminal 1 is increased by 1. As described above, according to the present embodiment, in each user terminal 1, The request converter 4 reduces the nonstationarity of packet requests that occur nonstationarily, and the slot management unit 5 converts the packet requests into a packet request sequence that is periodic and less random. The video data sequentially requested by the same terminal can be expected to be arranged relatively close to each other on the disk, assuming that the data is temporally continuously stored on the disk. Therefore, by periodically scheduling the disk device, it is possible to generate a very efficient scheduling table using the previous scheduling result. Further, the magnetic disk device 9 is controlled by the schedule table generated by the slot management device 5 and fully optimized by the scheduler 6, and can be operated with a very high read efficiency close to the maximum performance.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows the configuration of a video data reproducing system according to the second embodiment of the present invention. In the figure, the same components as those in FIG. 1 are designated by the same reference numerals.
The difference between the configurations shown in FIG. 1 and FIG. 2 is that in the system shown in FIG. 2, the buffer monitoring device 11 monitors the remaining amount of video data for each user terminal in the data buffer, and the request conversion device 4 In addition to the arrival frequency of the packet request signal from the user terminal, the slot management device 5 also takes this remaining amount into consideration.
A slot allocation signal to If the amount of data buffered in the data buffer is larger than the expected amount sent to the terminal in one cycle, a request is made that the slot allocation is smaller than the slot allocation estimated from the number of packet request signal arrivals. If the amount of data in the packet is smaller than the expected transmission amount to the terminal, it requests a larger allocation than the slot allocation estimated from the number of packet request signal arrivals.

According to this embodiment, the following advantages are brought about in addition to the effects provided by the first embodiment described above. That is, since the data amount in the data buffer is reflected in the slot allocation, the data amount in the data buffer can be made constant. Fluctuations in the buffer data amount due to long-term fluctuations in the packet request frequency from the user terminal can be alleviated, and the data buffer can be used efficiently.

[0029]

As described above, the present invention controls the periodicity of the read request output in the slot management unit based on the frequency of data requests from each user terminal obtained from the user control unit in the request conversion device. In the slot management device, the scheduling of data access to the data storage unit is periodically performed by the configuration in which the read request is periodically output to the read control unit according to the approximate data rate of the video data supplied to each of the user terminals. It is possible to improve the reading efficiency of the video data.

Further, the buffer monitoring device monitors the remaining amount of data corresponding to each terminal in the data buffer which temporarily stores the video data to be sent to each user terminal, and the request converter controls the user. Based on the frequency of data requests from each user terminal obtained from the unit and the remaining amount of video data sent from the buffer monitoring unit to each user terminal, the periodicity of the read request output in the slot management unit is controlled. With this configuration, it is possible to further improve the efficiency of reading the video data from the data storage unit and the efficiency of memory utilization of the data buffer.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a video data file device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a read table in the embodiment.

FIG. 3 is a configuration diagram of a schedule table in the same embodiment.

FIG. 4 is an operation diagram of the video server in the embodiment.

FIG. 5 is a configuration diagram of a video data file device according to a second embodiment of the present invention.

FIG. 6 is a block diagram of a video data reproducing system in a conventional example.

[Explanation of symbols]

 1 Video Server 2 User Terminal 3 User Control Device 4 Request Conversion Device 5 Slot Management Device 6 Scheduler 7 Read Control Device 8 Timer 9 Magnetic Disk Storage Device 10 Data Buffer 11 Buffer Monitoring Device

Claims (4)

[Claims] 1. A video data file device for supplying video data in response to data requests from a plurality of user terminals, the data storage unit storing video data, and the data read from the data storage unit. A data buffer for temporarily storing, a user control unit that monitors data requests from the plurality of user terminals, and sends video data from the data buffer to each user terminal, a timer unit that counts time, A read control unit that controls the order of reading the video data supplied to the plurality of user terminals from the data storage unit, time information obtained from the timer unit, and an approximate data rate of the video data supplied to each of the user terminals. Accordingly, the slot management unit that periodically outputs a read request to the read control unit and the timer management unit And a request conversion unit that controls the periodicity of the read request output in the slot management unit based on the time information and the frequency of data requests from each user terminal obtained from the user control unit. Data file device. 2. A buffer monitor unit in a data buffer for monitoring the remaining amount of video data to be sent to each of the plurality of user terminals, wherein the request conversion unit includes time information obtained from a timer unit and user control. Control of the periodicity of the read request output in the slot management unit, based on the frequency of data requests from each user terminal obtained from the buffer section and the remaining amount of video data sent from each buffer terminal to each user terminal. The video data file device according to claim 1, wherein 3. The video data file device according to claim 1, wherein the request conversion unit controls the number of read requests output from the slot management unit to the read control unit. 4. The video data file device according to claim 1, wherein the request conversion unit controls the data amount of the read request output from the slot management unit to the read control unit.